size of coupling suitable for ball mill to transformer

china customized ball mill gearbox manufacturers, suppliers - factory direct price - transpower

High grinding efficiency, large range of energy saving.Compared with ball mill system, it can save 30~50% electricity.Compared with the traditional vertical mill, the external circulation ratio is large, and the power consumption of the system can be reduced by about 20%.

High grinding efficiency, large range of energy saving.Compared with ball mill system, it can save 30~50% electricity.Compared with the traditional vertical mill, the external circulation ratio is large, and the power consumption of the system can be reduced by about 20%.

Our products are suitable for various fields, especially in intelligent kitchen, medical equipment, industrial equipment, security equipment, office supplies, robots, model aircraft and other fields.product are sold all over the world, by the consistent praise of customers.

Twin screw extruder in use for a period of time, screw back end and transmission bearing between the sealing bearing may appear wear, the gap between the two screw changes, screw back, thus causing friction.

rolling mill coupling - all industrial manufacturers - videos

{{#each product.specData:i}} {{name}}: {{value}} {{#i!=(product.specData.length-1)}} {{/end}} {{/each}}

{{#each product.specData:i}} {{name}}: {{value}} {{#i!=(product.specData.length-1)}} {{/end}} {{/each}}

ARCUSAFLEX - Highly torsionally flexible rubber disc coupling for internal combustion engine drives * Very high torsional exibility with a linear torsional deection characteristic * High torsional vibration and shock ...

MOM is an Oldham type flexible coupling. FCD400 is adopted in the spacer. Suitable for low-speed and high-torque specification. High performance grease is applied in the gap between hubs and the spacer in order to prevent ...

gland nut - an overview | sciencedirect topics

Because of its more complex construction and use in larger sizes and at higher temperatures than the less-complicated floating ball valve, several additional features are included, such as the following:

This particular valve is designed to a combination of specifications from API 6D for trunnion-mounted ball valves. The flanged ends are designed and drilled to ASME B16.5 specifications, but this valve is also available with butt-weld ends to ASME B16.25 specifications. The face-to-face dimensions are to API 6D and ASME B16.10 specifications.

Live loading is the term applied when some form of spring energization is included in the gland bolting system. It is normally achieved by using Belleville disc spring washers between the gland nuts and the gland follower. This provides additional compliance in the bolting applied to the gland follower. This will ensure satisfactory loading over a long period, but it is also important for maintaining satisfactory loading during temperature and pressure cycles and can avoid the use of excessive loading when new. It is typically necessary to use live loading to achieve a valve-packing performance that will comply with the various emission requirements within EPA, ISO and TA-Luft, etc.; see Appendix 1. The live loading will accommodate a wide range of variables that could affect the packing performance such as vibration, differential thermal expansion, packing relaxation and bolt creep. A diagrammatic live-loaded arrangement is shown in Figure 3.135.

Belleville washers offer a number of benefits for this type of application, including compactness, high spring force at low deflection, absence of set or fatigue under normal loads, a straight-line load/deflection curve, and simple adjustment by the addition or removal of individual springs. They come in a wide variety of materials from the relatively standard 17-7 PH stainless steel, to alternative stainless and alloy steels, phosphor bronze, and high-nickel alloys, depending on application [64].

The selection of springs and the spring force required will involve consideration of the operating environment and information from the packing supplier on the recommended packing stress for the type of packing to be used. Some suppliers offer a system with an enclosure, or contained unit. With a matched packing-set and spring combination, the enclosure can be tightened to give a prescribed loading to the packing [65]. A further claimed advantage of this arrangement is that it is then tamperproof.

The use of live loading on pump packing where the speed is higher is comparatively rare. The packing load is much lower and can be critical to individual applications. The selection of a suitable load and loading method is therefore more difficult and it can often cause a situation where continuous wear occurs and packing life is reduced.

For large rotary machines with slow rotational speed, such as driers and some mixers, again live loading can be a benefit, especially if access for adjustments is difficult or not possible. The loading method and compression load required will need careful consideration in liaison with the packing supplier.

29.1Explain the origins of friction between solid surfaces in contact.29.2The following diagram shows a compression joint for fixing copper water pipe to plumbing fittings. When assembling the joint the gland nut is first passed over the pipe followed by a circular wedge or "olive" made from soft copper. The nut is then screwed onto the end of the fitting and the backlash is taken up. Finally the nut is turned through a specified angle which compresses the olive on to the surface of the pipe. The specified angle is chosen so that it is just sufficient to make the cross-section of the pipe yield in compression over the length L in contact with the olive. Show that the water pressure required to make the pipe shoot out of the fitting is given approximately bypw=2y(tr)(Lr)where is the coefficient of friction between the olive and the outside of the pipe.Calculate pw given the following information: t = 0.65 mm, L = 7.5 mm, r = 7.5 mm, = 0.15, y = 120 MN m-2. Comment on your answer in relation to typical hydrostatic pressures in water systems.The axial load on the joint is pwr2 and the radial pressure applied to the outside of the pipe by the olive is P = yt/r.29.3Give examples, from your own experience, of situations where friction is (a) desirable, and (b) undesirable.29.4Give examples, from your own experience, of situations where wear is (a) desirable, and (b) undesirable29.5Bicycle chains often stretch during use. Referring to Example 13.4, this cannot be due to plastic extension or creep, because the material is hardened steel, with a factor of safety of 8.5 against yield. The stretch is in fact caused by wear between the links and the pins.I (DRHJ) find that I need to shorten my bicycle chain by 25 mm (two chain pitches) every five years or so. Estimate the radial wear on the pins and holes, assuming all contacting surfaces wear at the same rate. The number of links in the chain is currently 110. Take other dimensions from Example 13.4.29.6Soft metal gaskets are often used for gas-tight or liquid-tight seals between steel surfaces. Examples are the use of soft copper washers under the heads of drain plugs in car engine sumps, or indium gaskets between bolted stainless steel flanges in high-vacuum equipment (indium melts at only 156C, and is one of the softest metals known). Explain the principle involved in selecting a soft metal for such applications.29.7A washer for an oil drain plug has an outside diameter of 22 mm, an inside diameter of 15 mm, and is made from soft copper with a yield strength of 50 MN m2. The drain plug has a shank 15 mm in diameter, and is made from steel with a yield strength of 280 MN m2. The drain plug is torqued up until the copper yields. At this level of torque, estimate the ratio of the tensile stress in the shank to the yield stress of the steel. Comment on the practical significance of your answer.I (DRHJ), being an engineer, change the oil and filter on my car myself, and always reuse the copper washer (it saves me money, and I can't be bothered to go to the garage and buy a new one). But before replacing it, I always soften it by heating it to dull red heat over the gas hob in the kitchen. Why is it important to do this?29.8Electrical wiring circuits mainly use soft copper wires, and the ends are wired into plug sockets, switches, distribution boards, etc., using brass connectors fitted with brass grub screws to hold the wires in place. Why is it important to do the screws up tight? What can happen if the screws are not done up tight enough?29.9The wheels of railway locomotives, carriages, and wagons are often pressed on to their axles, as shown in this diagram of a pressing operation.Experiments have been carried out in which steel wheels were repeatedly pressed on and off steel axles. Before the wheel was pressed on each time, the interference of fit was measured (the difference between the diameter of the axle and the diameter of the wheel bore). The results are given in the following table.Pressing NumberInterference before Each Pressing (m) 021180Which physical process was responsible for the observed decrease in interference?29.10In 1951, a new class of steam locomotives built by British Railways (the 70,000, or Britannia class) started failing in service owing to the driving and coupled wheels slipping on their axles. The axles were fitted with roller bearings, which meant that the wheelset (the finished assembly of two wheels, axle, and roller bearings) could not be put into the wheel balancing machine for adjusting the lead balance weights. So instead, the wheels were first pressed on to a dummy axle, the temporary assembly was balanced in the balancing machine, the wheels were then pressed off the dummy axle, and finally were pressed on to the real axle. Why do you think this unusual method of assembly might have made it more likely that the wheels would slip in service?29.11The following diagram shows the arrangement of exhaust gas turbine and compressor wheel in a large turbocharger for a marine diesel engine. The compressor wheel is secured to the turbine shaft by an interference fit. The compressor wheel is aluminum alloy and the turbine shaft is steel. The shaft typically runs at 15,000 rpm.Given that the interference of fit is critical in this application, how would you assemble the compressor wheel to the turbine shaft without losing any interference?29.12This photograph shows a cattle grid on a bicycle path in Cambridge, England. There are many such grids in the city. The cross bars over which the cycles pass were originally round steel bars, galvanized so that they would not rust. In wet weather cyclists had to be very careful when crossing the grids, or they would skid sideways and fall off. Imagine that you are the City Engineer. Do you know what is causing this problem, and should you have foreseen it? How would you put this design error rightquickly and cheaply, of course? [A design feature, that they did get right, is the little ramp from the bottom of the pit to the upper edge of the cattle grid. It is to allow hedgehogs to escape if they have been unlucky enough to fall into the pit.] 52 11 41.85 N 0 07 00.22 E

The following diagram shows a compression joint for fixing copper water pipe to plumbing fittings. When assembling the joint the gland nut is first passed over the pipe followed by a circular wedge or "olive" made from soft copper. The nut is then screwed onto the end of the fitting and the backlash is taken up. Finally the nut is turned through a specified angle which compresses the olive on to the surface of the pipe. The specified angle is chosen so that it is just sufficient to make the cross-section of the pipe yield in compression over the length L in contact with the olive. Show that the water pressure required to make the pipe shoot out of the fitting is given approximately bypw=2y(tr)(Lr)where is the coefficient of friction between the olive and the outside of the pipe.

Bicycle chains often stretch during use. Referring to Example 13.4, this cannot be due to plastic extension or creep, because the material is hardened steel, with a factor of safety of 8.5 against yield. The stretch is in fact caused by wear between the links and the pins.

I (DRHJ) find that I need to shorten my bicycle chain by 25 mm (two chain pitches) every five years or so. Estimate the radial wear on the pins and holes, assuming all contacting surfaces wear at the same rate. The number of links in the chain is currently 110. Take other dimensions from Example 13.4.

Soft metal gaskets are often used for gas-tight or liquid-tight seals between steel surfaces. Examples are the use of soft copper washers under the heads of drain plugs in car engine sumps, or indium gaskets between bolted stainless steel flanges in high-vacuum equipment (indium melts at only 156C, and is one of the softest metals known). Explain the principle involved in selecting a soft metal for such applications.

A washer for an oil drain plug has an outside diameter of 22 mm, an inside diameter of 15 mm, and is made from soft copper with a yield strength of 50 MN m2. The drain plug has a shank 15 mm in diameter, and is made from steel with a yield strength of 280 MN m2. The drain plug is torqued up until the copper yields. At this level of torque, estimate the ratio of the tensile stress in the shank to the yield stress of the steel. Comment on the practical significance of your answer.

I (DRHJ), being an engineer, change the oil and filter on my car myself, and always reuse the copper washer (it saves me money, and I can't be bothered to go to the garage and buy a new one). But before replacing it, I always soften it by heating it to dull red heat over the gas hob in the kitchen. Why is it important to do this?

Electrical wiring circuits mainly use soft copper wires, and the ends are wired into plug sockets, switches, distribution boards, etc., using brass connectors fitted with brass grub screws to hold the wires in place. Why is it important to do the screws up tight? What can happen if the screws are not done up tight enough?

Experiments have been carried out in which steel wheels were repeatedly pressed on and off steel axles. Before the wheel was pressed on each time, the interference of fit was measured (the difference between the diameter of the axle and the diameter of the wheel bore). The results are given in the following table.Pressing NumberInterference before Each Pressing (m) 021180

In 1951, a new class of steam locomotives built by British Railways (the 70,000, or Britannia class) started failing in service owing to the driving and coupled wheels slipping on their axles. The axles were fitted with roller bearings, which meant that the wheelset (the finished assembly of two wheels, axle, and roller bearings) could not be put into the wheel balancing machine for adjusting the lead balance weights. So instead, the wheels were first pressed on to a dummy axle, the temporary assembly was balanced in the balancing machine, the wheels were then pressed off the dummy axle, and finally were pressed on to the real axle. Why do you think this unusual method of assembly might have made it more likely that the wheels would slip in service?

The following diagram shows the arrangement of exhaust gas turbine and compressor wheel in a large turbocharger for a marine diesel engine. The compressor wheel is secured to the turbine shaft by an interference fit. The compressor wheel is aluminum alloy and the turbine shaft is steel. The shaft typically runs at 15,000 rpm.

This photograph shows a cattle grid on a bicycle path in Cambridge, England. There are many such grids in the city. The cross bars over which the cycles pass were originally round steel bars, galvanized so that they would not rust. In wet weather cyclists had to be very careful when crossing the grids, or they would skid sideways and fall off. Imagine that you are the City Engineer. Do you know what is causing this problem, and should you have foreseen it? How would you put this design error rightquickly and cheaply, of course? [A design feature, that they did get right, is the little ramp from the bottom of the pit to the upper edge of the cattle grid. It is to allow hedgehogs to escape if they have been unlucky enough to fall into the pit.]

Failure mode. Excessive leakage at the seal frequently indicates face distortion. Distorted seal faces themselves will show a nonuniform wear pattern. Sometimes a nonuniform wear pattern is difficult to detect, but when a seal face is lightly polished on a lapping plate, high spots will clearly appear at two or more points if it is distorted. See Figure 3-156.

Causes. A number of factors can be responsible for seal face distortion:Improper assembly of seal parts may cause nonuniform loads at two or more points around the seal face. This frequently occurs with rigidly mounted or clamp-style seal faces, because uneven torquing of the gland nuts may transmit deflections directly to the seal faces.Improper cooling will induce thermal stresses and distortions at the seal faces.Improper finishing or processing of the seal parts may leave them with high spots at several points around the seal faces.Face distortion can be caused by improper gland support, resulting from debris or deposits left in the gland or by physical damage to the metal in the gland.Poor surface finish at the face of the seal housing, due to corrosion or mechanical damage, can also cause face distortion.

Improper assembly of seal parts may cause nonuniform loads at two or more points around the seal face. This frequently occurs with rigidly mounted or clamp-style seal faces, because uneven torquing of the gland nuts may transmit deflections directly to the seal faces.

Action.Relap the seal faces to remove the distortion.Consider the use of flexibly mounted stationary seal faces to compensate for any gland distortion.Readjust the gland by positioning the gland nuts finger-tight and then tighten them evenly with a torque wrench to an appropriate value.Check gland dimensions. Clean and check the seal housing face and gland finish.

Failure mode. Seal face deflection may be indicated by uneven wear at the seal face similar to that encountered with face distortion. The wear pattern, however, for seal face deflection is continuous for 360 degrees around the seal faces and is concave or convex. A convexed seal face usually results in abnormally high leakage rates, while one that is concaved usually results in excessive seal face torque and heat. See Figure 3-157. Seals exhibiting either condition will generally not be stable under cyclic pressure conditions.

Causes. Seal face deflection may arise from:Improper stationary seal face support.Swelling of secondary seals.Operation beyond the pressure limits of the seals.Inadequate balancing of hydraulic and mechanical loads on the primary seal faces.

Action.Check the seal design's operating limits and consult Durametallic Corporation to determine if another seal design is necessary.Consider flexible mounting of the stationary seal.Replace carbon seal faces with seal faces of materials having a higher modulus of elasticitylike bronze, silicon carbide, or tungsten carbide. These will have greater resistance to hydraulic and mechanical bending loads.

Replace carbon seal faces with seal faces of materials having a higher modulus of elasticitylike bronze, silicon carbide, or tungsten carbide. These will have greater resistance to hydraulic and mechanical bending loads.

Failure mode. O-rings or other secondary seals show deformation from being squeezed through the close clearances around the primary seal faces. Frequently these O-rings or secondary seals will appear cut or, in some cases, peeled. See Figure 3-158.

Action.Check O-ring clearances for the application. Replace O-ring if necessary. See Figure 3-159.Figure 3-159. Maximum allowable clearance for O-ring secondary seals.Check the chemical compatibility and temperature limits of the secondary seals. Replace if indicated.Install anti-extrusion rings if necessary.Check and correct the condition of the equipment.

Failure mode. Seal face may be eaten away or washed out in one localized area. See Figure 3-160. Erosion will commonly occur on a stationary seal face until seal face distortion or breakage occurs. Erosion most often takes place in seal faces of carbon-graphite, but can arise in other materials under severe conditions.

Causes. Excessive flush rates or a flush fluid contaminated with abrasive particles will cause erosion. Either condition will result in a sandblast effect on a localized area of the stationary seal face.

Action.Reduce the seal flush rate.Eliminate abrasives from the seal flush fluid by using filters or cyclone separators.Replace carbon seal faces with those of an erosion-resistant material such as bronze, tungsten carbide, or silicon carbide.Relocate the seal flush or install a shroud to protect the stationary seal face from the direct flow of the flush.

Causes. Premature wear can occur on drive mechanisms due to heavy loads or large degrees of movement between the drive mechanism and other wear surfaces. High wear rates may also occur with relatively little movement if the drive mechanism is not properly lubricated. Such may be the case, for example, in drive mechanisms that operate in dry environments or in environments containing abrasive particles.

Action.Check the condition of the equipment, and limit shaft end play, shaft deflections, or any out-of-squareness of the shaft with respect to the seal housing.Check the piloting and centering of the seal components.Incorporate hardened drive pins into the seal design.Consider seal designs, such as double seals, that will put the drive mechanism in a better lubricating environment.Check pressure limitations of the seal design.

The parallel gate valve is manufactured in three gate designs which have different characteristics. The gate is usually made in two halves which are spring-loaded against the seats. One design relies on the initial spring load plus the line pressure to create the seal. This type of valve can only seal on one seat. The other valve style includes a wedge between the spring-loaded halves, see Figure 3.2. The initial seat force is provided by the springs. As the stem is screwed in further a wedge forces the halves apart and increases the seat force on both seats. This type of valve seals both seats simultaneously. The gate can be made solid, see the later description of compact parallel gate valves.

Figure 3.2 shows a parallel gate valve with wedged gate discs. The valve has a bolted bonnet and bolted gland. It can be difficult to maintain even-loading and alignment on two bolt glands and good designs have a gland with a self-aligning follower. Phosphor bronze gland nuts for hot applications are much better than steel ones. The valve shown has a separate yoke. The yoke is clamped to the bonnet. Separate yokes make it much easier to repack the box. Valves for outdoor applications should also have lubrication facilities for the handwheel nut. Parallel gate valves are suitable for clean fluids. Entrained solids increase wear and leakage results. The spring-loaded version is suitable for applications where significant temperature changes occur and where valve body distortion may be a problem. As only one seat is loaded when the valve is closed the gate cannot be jammed. The wedged version can be jammed closed by temperature changes. Because both seats are sealed, significant temperature increases may create high pressures in the valve cavity. Manufacturers should be consulted about cavity relief.

Parallel gate valves have an unobstructed bore when wide open. Low friction losses and high Cv values result. Some valves may have reduced ports which will make pigging impractical, so ensure sizes are checked before purchasing. Flow regulation is only possible by inducing very high local velocities which can result in rapid wear and erosion. These valves should only be used for isolation. Gate valves are slow to operate manually, resulting in no water hammer problems.

Parallel gate valves are very popular for power generation applications. Cast and forged steel and alloy steel valves are available in many sizes, see Table 3.1. Valves larger than DN40 for pressures over ANSI Class 900lb may have bonnets secured by shear rings.

Parallel gate valves can be built as compact shorter versions to save space. These valves are sometimes described as wafer gate valves. In this context wafer is used to mean thin. These valves are not clamped between two pipe flanges as the name would normally imply. Valve length is reduced by incorporating the flange facings directly into the body, see Figure 3.5.

The flanges are facings only, studbolts with two nuts or bolts and nuts cannot be used. The valve facing can be fitted with studs in those installations where the valve body is unlikely to be removed. Alternatively bolts must be used. When bolting is used, for valves which may be removed routinely, thread inserts in the valve body are a sound investment. The body can have a bottom clean out cover. The gate is solid. Sealing is effected by spring-loaded seats. The seats may have elastomer inserts and O ring seals. Cast carbon steel body and bonnets are standard for low pressure ANSI 150lb valves with 11/13 Cr trim. Gates are usually plated carbon steel. Sizes range from DN100 to DN1 200, and larger valves can can also be built.

Anaesthetists require a continuous indication of gas flows in the anaesthetic machine and this is provided by a variable orifice flowmeter, often referred to by the trade name of Rotameter. Figure 3.8A illustrates the flowmeter. A bobbin is supported in the middle of a tapered glass or plastic tube by the gas flow and, as the flow increases, the bobbin rises in the tube and the clearance round the bobbin increases. In other words, there is a variable orifice round the bobbin which depends on the gas flow. The pressure across the bobbin remains constant because it gives rise to a force which balances the force of gravity on the bobbin. The increase in the area of the annular orifice as the bobbin rises reduces flow resistance at higher flows and so the pressure across the bobbin stays constant, despite the flow increase.

In a variable orifice flowmeter there is a mixture of turbulent and laminar flow, and so for calibration purposes both the density and viscosity of the fluid are important (Chapter 2). Consequently, careful recalibration is required if a flowmeter is used for a different fluid than that for which it was initially designed.

The flowmeter tube must be kept vertical to obtain a correct reading and to prevent the bobbin touching the sides of the tube and sticking. Sticking is more likely to occur when the bobbin is rotating near the bottom of the tube. Electrostatic charges may also build up on the bobbin if it rubs against the side of the tube, and these may increase the tendency to stick. To prevent the build-up of such charges, some tubes have a conductive strip running down the inside at the back, while in others a clear conductive coating is provided inside to conduct away any electrostatic charges.

The problem of sticking is less if a simple ball flowmeter is used as shown in Fig. 3.8B, but this may be less accurate because there is no well-defined surface to read. In practice, the readings are taken from the middle of the ball.

In the illustration (Fig. 3.8) the flowmeters have a bore with a simple straight wall taper but in practice the bore is usually specially moulded with a varying taper so that both low and high flows can be measured conveniently. This is essential if anaesthetists wish to use the same flowmeter for low flows to a closed circuit and also for high flow systems. Added accuracy can be achieved if two flowmeters, one for low and one for high flows are used in tandem. With such systems new flowmeters normally indicate flows within 2.5% of the true value whereas inaccuracies of over 5% have been reported with older types of flowmeter.

Below the flowmeter there is usually a needle valve, as illustrated in Fig. 3.9. In the needle valve there is a spindle, attached to a control knob which screws into the seating of the inlet to turn off the gas supply to the flowmeter above. Leakage of gas around the spindle is prevented by a gland with its gland nut. A gland is a washer of compressible material, and glands and gland nuts are also used to prevent leakage on gas cylinders. At the bottom of each flowmeter a dust filter of sintered metal is also present.

The principle of flow through the valve differs from that described in Chapter 2 in that, at a normal gas supply pressure the linear velocity of the gas round the control spindle approaches the speed of sound and achieves a constant maximum value. Consequently, the flow only depends upon the area of the channel and is unaffected by small changes of upstream pressure e.g. at the outlet of the flowmeters. This is an advantage to the anaesthetist as it means that the gas flows, once set, do not alter when additional apparatus such as a vaporizer or a Manley ventilator is attached at the outlet of the flowmeters, though the bobbin position may alter slightly, as described later.

The positions of individual gas flowmeters on the anaesthetic machine may cause problems, as illustrated in Fig. 3.10A. If there is a leak in the centre flowmeter or in the centre of the block, more oxygen (from the left) leaks out through this hole than nitrous oxide, resulting in a higher percentage of nitrous oxide than intended being delivered to the patient, perhaps with fatal consequences.

One solution would be to reverse the oxygen and nitrous oxide flowmeter positions as shown in Fig. 3.10B, and these positions may be found in North America. Unfortunately, many anaesthetists are so used to the current position that this solution is not universally acceptable. Therefore, on some machines another solution, illustrated in Fig. 3.10C, is found. Here there is suitable channelling present in order to pick up the oxygen selectively. As an additional safety measure it is now recommended that there should be no risk of administration of less than 25% oxygen. To achieve this many anaesthetic machines in the USA and in Britain now have a chain linking the oxygen and nitrous oxide flowmeters so that oxygen always flows when the nitrous oxide is turned on. Pneumatic mixing valves have also been used to give the same effect.

From the outlets of the flowmeters the gas may pass to vaporizers and a ventilator and this may cause the pressure to increase at the outlet of the flowmeters. A pressure increase affects calibration due to alteration in the density and viscosity of the gases. There is then a slight inaccuracy in the indicated flow even if allowance is made for the re-expansion of gas to ambient pressure. Some flowmeters now have the flow controls on the outlet so that they are pressurized and calibrated to work at an increased pressure of several bar. This minimizes the effect of the relatively smaller pressure changes at the outlet.

A second instrument which measures flow by the variable orifice principle is the Wright peak flowmeter illustrated in Fig. 3.11. In this flowmeter the patient's expired gases are directed against a moveable vane causing it to rotate. As the vane rotates, it opens up a circular slot around the base of the instrument and so allows the gases to escape. Rotation of the vane is opposed by the force from a coiled spring and a pointer mounted on the axis of the vane registers its movement on a calibrated dial. The spring force is relatively constant and its action on the area of the vane gives a very small steady pressure to balance the constant pressure driving the flow of gas through the variable orifice. The size of this orifice increases to that required for the gas flow and, at peak flow, the vane reaches a maximum position from which it is prevented from returning by a ratchet. After the maximum reading is taken, the vane can be released by depressing a button and the pointer returns to zero. An alternative, more compact peak flowmeter, has a cylindrical shape and the air escapes from a straight slot in place of the circular one described. However, the variable orifice principle is still used. For an adult a peak flow of 400 to 500 litre min1 is common but in a patient with emphysema this may be below 100 litre min1.

In research applications in anaesthesia a continuous recording of a patient's respiratory volume and airflow may be needed, and in such cases a pneumotachograph may be used (Fig. 3.12). The measuring head of this instrument contains a gauze screen and has a sufficiently large diameter to ensure laminar flow through the gauze. The gauze acts as a resistance to flow, and so respiratory airflow from the patient causes a small pressure drop across the gauze. This pressure change is measured by a transducer which converts the pressure change into an electrical signal which in turn can be displayed and recorded. (The word transducer describes a device which changes a signal from one form of energy to another.) The pneumotachograph can measure rapid changes in the patient's respiration, at the same time avoiding any appreciable resistance to breathing. As laminar flow depends on fluid viscosity and turbulent flow on density, changes in the character of the gas passing through the pneumotachograph alter its accuracy; for example, changes of temperature or the addition of anaesthetic gases can affect the calibration. To overcome the problem of changes in temperature of the gases passing through them, the heads of some pneumotachographs are maintained at a constant warm temperature by a heating element. This also has the advantage of preventing water vapour in the expired gas from condensing out on the gauze. In addition to its use to measure flow, the pneumotachograph may be used to record volume by integrating the flow through it electronically (Chapter 25).

Another flowmeter used for calibration or for research purposes is the bubble flowmeter (Fig. 3.13). In this flowmeter a soap solution is used to produce a soap film at the base of a burette. The gas flow is directed up this burette and the rise of the film between two fixed points indicates the flow, the rate of rise being measured by a stop watch. The advantages of this system are that the film is very light and does not obstruct flow and the system is not dependent on the composition of the gases flowing. On the other hand, the bubble flowmeter is suitable only for low flows.

If the stuffing box is water-cooled, connect flexible water line with a valve in the drain return line to regulate flow. Discharge the cooling water into an open funnel so visual inspection will show water flowing. Adjust water flow to conditions.

If the gland cannot be loosened further, take out one row of packing. Replace the gland, finger tightening the bolts. Run the fan for a few hours until you can take up on the gland. Coat the row of packing removed earlier with light oil and then replace.

Set the motor on its magnetic center. This is marked on many motors. The magnetic center must be known to properly adjust the clearance between the face of the hubs. If the driver is a sleeve-bearing motor, its magnetic center must be found before aligning the coupling to prevent the motor side of the coupling from moving against the fan coupling. To find the axial movement of the motor shaft: a.Run motor and mark a line on the shaft; this is the magnetic center.b.Push the shaft as far as it will go into the motor housing. Mark line on shaft at housing. Then pull the shaft out as far as possible and scribe another line. Half the distance between the two marks is the mechanical center.

Push the shaft as far as it will go into the motor housing. Mark line on shaft at housing. Then pull the shaft out as far as possible and scribe another line. Half the distance between the two marks is the mechanical center.

(2) Finding the magnetic center is not necessary on ball bearing motors as their thrust bearings prevent movement. Axially soft couplings must be used on dual drive units where there is thermal expansion of the shaft. If motor incorporates sleave bearings use a limited end float coupling to restrict movement.

Attach the outlet dampers or the inlet box dampers using suitable gasket material. Use drift pins for positioning only and not to force the damper into place. These parts will fit as they have been completely assembled at the factory unless they have been damaged in erection or shipping.

If an inlet box damper control shaft is used, it is shipped in a separate box with the dampers mounted and with the levers pinned in place on shafts. Mount the entire jack shaft and connect the individual dampers. See your fan assembly drawing for positioning.

For double-width fans, the linkage from the vanes on each side is connected to the jack shaft that mounts on the fan housing. On double-width fans, if the jack shaft levers connecting each set of vanes do not line up with the connecting rods, the lever has been moved to protect it during shipment. Remove the pin from the jack shaft, slide levers back into position, carefully lining up the pin holes in levers, and replace the pin. Attach the connecting rods from individual mechanisms.

If the fan being erected is to operate at high temperatures, expansion joints are absolutely necessary at the fan connections. They allow for expansion of the fan housing and connecting ductwork without distorting each other. Remove any shipping braces from the expansion joints before operating the fan and provide for fan expansion in setting the housing foundation. Do not use drift pins, come-alongs, or any other means to force connections of ducts, fan housings, or inlet boxes.

During erection of the oil piping, be sure that the system is free from dirt, grit, weld spatter, or shavings. The piping system must be thoroughly cleaned and flushed before connecting to the bearings. Clean the filters before initial start-up.

After the selection of which pump is to be used (if a two-motor/pump system), the motor is turned on to activate the pump. Oil passes from the tank through the filter element, pump, pressure relief valve, oil cooler, sleeve bearings, and then by gravity back to the reservoir tank.

The circulating oil system must be operating before the fan can be started. Depending on the system specified, any malfunction in the system, low oil pressure, high temperature, etc., may either sound an alarm or shut down the fan. The oil system must operate 30 minutes after the fan is shut off or until the heat in the bearings has dissipated to an acceptable level.

input and output coupling | bipolar junction transistors | electronics textbook

To overcome the challenge of creating necessary DC bias voltage for an amplifiers input signal without resorting to the insertion of a battery in series with the AC signal source, we used a voltage divider connected across the DC power source. To make this work in conjunction with an AC input signal, we coupled the signal source to the divider through a capacitor, which acted as a high-pass filter. With that filtering in place, the low impedance of the AC signal source couldnt short out the DC voltage dropped across the bottom resistor of the voltage divider. A simple solution, but not without any disadvantages.

Most obvious is the fact that using a high-pass filter capacitor to couple the signal source to the amplifier means that the amplifier can only amplify AC signals. A steady, DC voltage applied to the input would be blocked by the coupling capacitor just as much as the voltage divider bias voltage is blocked from the input source. Furthermore, since capacitive reactance is frequency-dependent, lower-frequency AC signals will not be amplified as much as higher-frequency signals. Non-sinusoidal signals will tend to be distorted, as the capacitor responds differently to each of the signals constituent harmonics.

In this mode, a coupling capacitor is inserted in series with the measured voltage signal to eliminate any vertical offset of the displayed waveform due to DC voltage combined with the signal. This works fine when the AC component of the measured signal is of a fairly high frequency, and the capacitor offers little impedance to the signal. However, if the signal is of a low frequency, or contains considerable levels of harmonics over a wide frequency range, the oscilloscope displays of the waveform will not be accurate.

In applications where the limitations of capacitive coupling (considering the figure above) would be intolerable, another solution may be used: direct coupling. Direct coupling avoids the use of capacitors or any other frequency-dependent coupling component in favor of resistors. A direct-coupled amplifier circuit is shown in the figure below.

With no capacitor to filter the input signal, this form of coupling exhibits no frequency dependence. DC and AC signals alike will be amplified by the transistor with the same gain (the transistor itself may tend to amplify some frequencies better than others, but that is another subject entirely!).

If direct coupling works for DC as well as for AC signals, then why use capacitive coupling for any application? One reason might be to avoid any unwanted DC bias voltage naturally present in the signal to be amplified. Some AC signals may be superimposed on an uncontrolled DC voltage right from the source, and an uncontrolled DC voltage would make reliable transistor biasing impossible. The high-pass filtering offered by a coupling capacitor would work well here to avoid biasing problems.

Another reason to use capacitive coupling rather than direct is its relative lack of signal attenuation. Direct coupling through a resistor has the disadvantage of attenuating the input signal so that only a fraction of it reaches the base of the transistor. In many applications, some attenuation is necessary anyway to prevent signal levels from overdriving the transistor into cutoff and saturation, so any attenuation inherent to the coupling network is useful anyway. However, some applications require that there be no signal loss from the input connection to the transistors base for maximum voltage gain, and a direct coupling scheme with a voltage divider for bias simply wont suffice.

So far, weve discussed a couple of methods for coupling an input signal to an amplifier, but havent addressed the issue of coupling an amplifiers output to a load. The example circuit used to illustrate input coupling will serve well to illustrate the issues involved with output coupling.

In our example circuit, the load is a speaker. Most speakers are electromagnetic in design: that is, they use the force generated by a lightweight electromagnet coil suspended within a strong permanent-magnet field to move a thin paper or plastic cone, producing vibrations in the air which our ears interpret as sound. An applied voltage of one polarity moves the cone outward, while a voltage of the opposite polarity will move the cone inward. To exploit cones full freedom of motion, the speaker must receive true (unbiased) AC voltage. DC bias applied to the speaker coil offsets the cone from its natural center position, and this limits the back-and-forth motion it can sustain from the applied AC voltage without over traveling. However, our example circuit applies a varying voltage of only one polarity across the speaker, because the speaker is connected in series with the transistor which can only conduct current one way. This would be unacceptable for any high-power audio amplifier.

Somehow we need to isolate the speaker from the DC bias of the collector current so that it only receives AC voltage. One way to achieve this goal is to couple the transistor collector circuit to the speaker through a transformer in Figure below.

The voltage induced in the secondary (speaker-side) of the transformer will be strictly due to variations in collector current because the mutual inductance of a transformer only works on changes in winding current. In other words, only the AC portion of the collector current signal will be coupled to the secondary side for powering the speaker. The speaker will see true alternating current at its terminals, without any DC bias.

Transformer output coupling works and has the added benefit of being able to provide impedance matching between the transistor circuit and the speaker coil with custom winding ratios. However, transformers tend to be large and heavy, especially for high-power applications. Also, it is difficult to engineer a transformer to handle signals over a wide range of frequencies, which is almost always required for audio applications. To make matters worse, DC current through the primary winding adds to the magnetization of the core in one polarity only, which tends to make the transformer core saturate more easily in one AC polarity cycle than the other. This problem is reminiscent of having the speaker directly connected in series with the transistor: a DC bias current tends to limit how much output signal amplitude the system can handle without distortion. Generally, though, a transformer can be designed to handle a lot more DC bias current than a speaker without running into trouble, so transformer coupling is still a viable solution in most cases. See the coupling transformer between Q4 and the speaker, Regency TR1, Ch 9 as an example of transformer coupling.

Another method to isolate the speaker from DC bias in the output signal is to alter the circuit a bit and use a coupling capacitor in a manner similar to coupling the input signal (Figure below) to the amplifier.

This circuit in Figure above resembles the more conventional form of a common-emitter amplifier, with the transistor collector connected to the battery through a resistor. The capacitor acts as a high-pass filter, passing most of the AC voltage to the speaker while blocking all DC voltage. Again, the value of this coupling capacitor is chosen so that its impedance at the expected signal frequency will be arbitrarily low.

The blocking of DC voltage from an amplifiers output, be it via a transformer or a capacitor, is useful not only in coupling an amplifier to a load but also in coupling one amplifier to another amplifier. Staged amplifiers are often used to achieve higher power gains than what would be possible using a single transistor as in Figure below.

While it is possible to directly couple each stage to the next (via a resistor rather than a capacitor), this makes the whole amplifier very sensitive to variations in the DC bias voltage of the first stage, since that DC voltage will be amplified along with the AC signal until the last stage. In other words, the biasing of the first stage will affect the biasing of the second stage, and so on. However, if the stages are capacitively coupled shown in the above illustration, the biasing of one stage does not affect on the biasing of the next, because DC voltage is blocked from passing on to the next stage.

Transformer coupling between amplifier stages is also a possibility, but less often seen due to some of the problems inherent to transformers mentioned previously. One notable exception to this rule is in radio-frequency amplifiers (Figure below) with small coupling transformers, having air cores (making them immune to saturation effects), that are part of a resonant circuit to block unwanted harmonic frequencies from passing on to subsequent stages. The use of resonant circuits assumes that the signal frequency remains constant, which is typical of radio circuitry. Also, the flywheel effect of LC tank circuits allows for class C operation for high efficiency.

Note the transformer coupling between transistors Q1, Q2, Q3, and Q4, Regency TR1, Ch 9. The three intermediate frequency (IF) transformers within the dashed boxes couple the IF signal from collector to base of following transistor IF amplifiers. The intermediate frequency amplifiers are RF amplifiers, though, at a different frequency than the antenna RF input.

Having said all this, it must be mentioned that it is possible to use direct coupling within a multi-stage transistor amplifier circuit. In cases where the amplifier is expected to handle DC signals, this is the only alternative.

The trend of electronics to the more widespread use of integrated circuits has encouraged the use of direct coupling over transformer or capacitor coupling. The only easily manufactured integrated circuit component is the transistor. Moderate quality resistors can also be produced. Though, transistors are favored. Integrated capacitors to only a few 10s of pF are possible. Large capacitors are not integrable. If necessary, these can be external components. The same is true of transformers. Since integrated transistors are inexpensive, as many transistors as possible are substituted for the offending capacitors and transformers. As much direct-coupled gain as possible is designed into ICs between the external coupling components. While external capacitors and transformers are used, these are even being designed out if possible. The result is that a modern IC radio (See IC radio, Ch 9 ) looks nothing like the original 4-transistor radio Regency TR1, Ch 9.

Even discrete transistors are inexpensive compared with transformers. Bulky audio transformers can be replaced by transistors. For example, a common-collector (emitter follower) configuration can impedance match a low output impedance like a speaker. It is also possible to replace large coupling capacitors with transistor circuitry.

The circuit in Figure below (a) is a simplified transformer-coupled push-pull audio amplifier. In push-pull, pair of transistors alternately amplify the positive and negative portions of the input signal. Neither transistor conducts for no signal input. A positive input signal will be positive at the top of the transformer secondary causing the top transistor to conduct. A negative input will yield a positive signal at the bottom of the secondary, driving the bottom transistor into conduction. Thus the transistors amplify alternate halves of a signal. As drawn, neither transistor in Figure below (a) will conduct for an input below 0.7 Vpeak. A practical circuit connects the secondary center tap to a 0.7 V (or greater) resistor divider instead of ground to bias both transistor for true class B.

The circuit in Figure above (b) is the modern version that replaces the transformer functions with transistors. Transistors Q1 and Q2 are common emitter amplifiers, inverting the signal with gain from base to collector. Transistors Q3 and Q4 are known as a complementary pair because these NPN and PNP transistors amplify alternate halves (positive and negative, respectively) of the waveform. The parallel connection of the bases allows phase splitting without an input transformer at (a). The speaker is the emitter load for Q3 and Q4. Parallel connection of the emitters of the NPN and PNP transistors eliminates the center-tapped output transformer at (a) The low output impedance of the emitter follower serves to match the low 8 impedance of the speaker to the preceding common-emitter stage. Thus, inexpensive transistors replace transformers. For the complete circuit see Direct coupled complementary symmetry 3 w audio amplifier, Ch 9

couplings for motors and lead screws

Couple your shafts end to end! We sell couplings in a variety of sizes and styles. Couplings are simply used to enable a motor to turn a lead screw, or other type of shaft. There are two types of couplings, rigid (one piece), and flexible (an assembly of pieces). Flexible couplings are composed of two hubs and a central spider. One hub is fastened to a motor shaft with a set screw. The other hub is fastened to the lead screw end. The rubber spider enables the two hubs to connect and turn while still allowing for a bit of flexibility in alignment and angle. Below, you will find rigid couplings and coupling sets that include two hubs and one spider for common uses, and you can purchase coupling hubs and spiders separately. Please read the conditions of purchase prior to purchasing any products offered by BuildYourCNC.com.

Generally, the motor shaft with a 1/2" diameter will be inserted in one end, and a shaft, or lead screw also measuring 1/2" in diameter will be inserted into the other end. The screws that clamp the shafts will be tightened. These steel clamping coupling are for use with high torque motors and high inertia when the motor is changing directions.

Rigid couplings will keep backlash to a minimum, since the coupling is one single piece. Generally, the motor shaft with a 1/4" diameter will be inserted in one end, and a shaft, or lead screw also measuring 1/4" in diameter will be inserted into the other end. The screws that clamp the shafts will be tightened, but not too much. These types of clamping couplings will not damage the shafts.

vale operation in ontario gets upgrades to ore-processing mill - canadian manufacturing

According to ABB, the upgrades to Vales existing Clarabelle dual pinion semi-autogenous (SAG) mill will allow it to reduce the size of the ore at the companys nickel and copper mines in the Sudbury, Ont., area.

Engineering and construction of the building extension included excavation, foundation, civil, structural steel and architectural works as well as insulation, fire system, lighting, heating, ventilation and air conditioning.

Canadian Manufacturing magazine is the top source for daily industry-focused news in Canada. We cover the world of manufacturing across all the sectors industries, and we share stories that impact your business each day, providing news, in-depth articles and expert commentary.

ball mill - an overview | sciencedirect topics

The ball mill accepts the SAG or AG mill product. Ball mills give a controlled final grind and produce flotation feed of a uniform size. Ball mills tumble iron or steel balls with the ore. The balls are initially 510 cm diameter but gradually wear away as grinding of the ore proceeds. The feed to ball mills (dry basis) is typically 75 vol.-% ore and 25% steel.

The ball mill is operated in closed circuit with a particle-size measurement device and size-control cyclones. The cyclones send correct-size material on to flotation and direct oversize material back to the ball mill for further grinding.

Grinding elements in ball mills travel at different velocities. Therefore, collision force, direction and kinetic energy between two or more elements vary greatly within the ball charge. Frictional wear or rubbing forces act on the particles, as well as collision energy. These forces are derived from the rotational motion of the balls and movement of particles within the mill and contact zones of colliding balls.

By rotation of the mill body, due to friction between mill wall and balls, the latter rise in the direction of rotation till a helix angle does not exceed the angle of repose, whereupon, the balls roll down. Increasing of rotation rate leads to growth of the centrifugal force and the helix angle increases, correspondingly, till the component of weight strength of balls become larger than the centrifugal force. From this moment the balls are beginning to fall down, describing during falling certain parabolic curves (Figure 2.7). With the further increase of rotation rate, the centrifugal force may become so large that balls will turn together with the mill body without falling down. The critical speed n (rpm) when the balls are attached to the wall due to centrifugation:

where Dm is the mill diameter in meters. The optimum rotational speed is usually set at 6580% of the critical speed. These data are approximate and may not be valid for metal particles that tend to agglomerate by welding.

The degree of filling the mill with balls also influences productivity of the mill and milling efficiency. With excessive filling, the rising balls collide with falling ones. Generally, filling the mill by balls must not exceed 3035% of its volume.

The mill productivity also depends on many other factors: physical-chemical properties of feed material, filling of the mill by balls and their sizes, armor surface shape, speed of rotation, milling fineness and timely moving off of ground product.

where b.ap is the apparent density of the balls; l is the degree of filling of the mill by balls; n is revolutions per minute; 1, and 2 are coefficients of efficiency of electric engine and drive, respectively.

A feature of ball mills is their high specific energy consumption; a mill filled with balls, working idle, consumes approximately as much energy as at full-scale capacity, i.e. during grinding of material. Therefore, it is most disadvantageous to use a ball mill at less than full capacity.

The ball mill is a tumbling mill that uses steel balls as the grinding media. The length of the cylindrical shell is usually 11.5 times the shell diameter (Figure 8.11). The feed can be dry, with less than 3% moisture to minimize ball coating, or slurry containing 2040% water by weight. Ball mills are employed in either primary or secondary grinding applications. In primary applications, they receive their feed from crushers, and in secondary applications, they receive their feed from rod mills, AG mills, or SAG mills.

Ball mills are filled up to 40% with steel balls (with 3080mm diameter), which effectively grind the ore. The material that is to be ground fills the voids between the balls. The tumbling balls capture the particles in ball/ball or ball/liner events and load them to the point of fracture.

When hard pebbles rather than steel balls are used for the grinding media, the mills are known as pebble mills. As mentioned earlier, pebble mills are widely used in the North American taconite iron ore operations. Since the weight of pebbles per unit volume is 3555% of that of steel balls, and as the power input is directly proportional to the volume weight of the grinding medium, the power input and capacity of pebble mills are correspondingly lower. Thus, in a given grinding circuit, for a certain feed rate, a pebble mill would be much larger than a ball mill, with correspondingly a higher capital cost. However, the increase in capital cost is justified economically by a reduction in operating cost attributed to the elimination of steel grinding media.

In general, ball mills can be operated either wet or dry and are capable of producing products in the order of 100m. This represents reduction ratios of as great as 100. Very large tonnages can be ground with these ball mills because they are very effective material handling devices. Ball mills are rated by power rather than capacity. Today, the largest ball mill in operation is 8.53m diameter and 13.41m long with a corresponding motor power of 22MW (Toromocho, private communications).

Planetary ball mills. A planetary ball mill consists of at least one grinding jar, which is arranged eccentrically on a so-called sun wheel. The direction of movement of the sun wheel is opposite to that of the grinding jars according to a fixed ratio. The grinding balls in the grinding jars are subjected to superimposed rotational movements. The jars are moved around their own axis and, in the opposite direction, around the axis of the sun wheel at uniform speed and uniform rotation ratios. The result is that the superimposition of the centrifugal forces changes constantly (Coriolis motion). The grinding balls describe a semicircular movement, separate from the inside wall, and collide with the opposite surface at high impact energy. The difference in speeds produces an interaction between frictional and impact forces, which releases high dynamic energies. The interplay between these forces produces the high and very effective degree of size reduction of the planetary ball mill. Planetary ball mills are smaller than common ball mills, and are mainly used in laboratories for grinding sample material down to very small sizes.

Vibration mill. Twin- and three-tube vibrating mills are driven by an unbalanced drive. The entire filling of the grinding cylinders, which comprises the grinding media and the feed material, constantly receives impulses from the circular vibrations in the body of the mill. The grinding action itself is produced by the rotation of the grinding media in the opposite direction to the driving rotation and by continuous head-on collisions of the grinding media. The residence time of the material contained in the grinding cylinders is determined by the quantity of the flowing material. The residence time can also be influenced by using damming devices. The sample passes through the grinding cylinders in a helical curve and slides down from the inflow to the outflow. The high degree of fineness achieved is the result of this long grinding procedure. Continuous feeding is carried out by vibrating feeders, rotary valves, or conveyor screws. The product is subsequently conveyed either pneumatically or mechanically. They are basically used to homogenize food and feed.

CryoGrinder. As small samples (100 mg or <20 ml) are difficult to recover from a standard mortar and pestle, the CryoGrinder serves as an alternative. The CryoGrinder is a miniature mortar shaped as a small well and a tightly fitting pestle. The CryoGrinder is prechilled, then samples are added to the well and ground by a handheld cordless screwdriver. The homogenization and collection of the sample is highly efficient. In environmental analysis, this system is used when very small samples are available, such as small organisms or organs (brains, hepatopancreas, etc.).

The vibratory ball mill is another kind of high-energy ball mill that is used mainly for preparing amorphous alloys. The vials capacities in the vibratory mills are smaller (about 10 ml in volume) compared to the previous types of mills. In this mill, the charge of the powder and milling tools are agitated in three perpendicular directions (Fig. 1.6) at very high speed, as high as 1200 rpm.

Another type of the vibratory ball mill, which is used at the van der Waals-Zeeman Laboratory, consists of a stainless steel vial with a hardened steel bottom, and a single hardened steel ball of 6 cm in diameter (Fig. 1.7).

The mill is evacuated during milling to a pressure of 106 Torr, in order to avoid reactions with a gas atmosphere.[44] Subsequently, this mill is suitable for mechanical alloying of some special systems that are highly reactive with the surrounding atmosphere, such as rare earth elements.

A ball mill is a relatively simple apparatus in which the motion of the reactor, or of a part of it, induces a series of collisions of balls with each other and with the reactor walls (Suryanarayana, 2001). At each collision, a fraction of the powder inside the reactor is trapped between the colliding surfaces of the milling tools and submitted to a mechanical load at relatively high strain rates (Suryanarayana, 2001). This load generates a local nonhydrostatic mechanical stress at every point of contact between any pair of powder particles. The specific features of the deformation processes induced by these stresses depend on the intensity of the mechanical stresses themselves, on the details of the powder particle arrangement, that is on the topology of the contact network, and on the physical and chemical properties of powders (Martin et al., 2003; Delogu, 2008a). At the end of any given collision event, the powder that has been trapped is remixed with the powder that has not undergone this process. Correspondingly, at any instant in the mechanical processing, the whole powder charge includes fractions of powder that have undergone a different number of collisions.

The individual reactive processes at the perturbed interface between metallic elements are expected to occur on timescales that are, at most, comparable with the collision duration (Hammerberg et al., 1998; Urakaev and Boldyrev, 2000; Lund and Schuh, 2003; Delogu and Cocco, 2005a,b). Therefore, unless the ball mill is characterized by unusually high rates of powder mixing and frequency of collisions, reactive events initiated by local deformation processes at a given collision are not affected by a successive collision. Indeed, the time interval between successive collisions is significantly longer than the time period required by local structural perturbations for full relaxation (Hammerberg et al., 1998; Urakaev and Boldyrev, 2000; Lund and Schuh, 2003; Delogu and Cocco, 2005a,b).

These few considerations suffice to point out the two fundamental features of powder processing by ball milling, which in turn govern the MA processes in ball mills. First, mechanical processing by ball milling is a discrete processing method. Second, it has statistical character. All of this has important consequences for the study of the kinetics of MA processes. The fact that local deformation events are connected to individual collisions suggests that absolute time is not an appropriate reference quantity to describe mechanically induced phase transformations. Such a description should rather be made as a function of the number of collisions (Delogu et al., 2004). A satisfactory description of the MA kinetics must also account for the intrinsic statistical character of powder processing by ball milling. The amount of powder trapped in any given collision, at the end of collision is indeed substantially remixed with the other powder in the reactor. It follows that the same amount, or a fraction of it, could at least in principle be trapped again in the successive collision.

This is undoubtedly a difficult aspect to take into account in a mathematical description of MA kinetics. There are at least two extreme cases to consider. On the one hand, it could be assumed that the powder trapped in a given collision cannot be trapped in the successive one. On the other, it could be assumed that powder mixing is ideal and that the amount of powder trapped at a given collision has the same probability of being processed in the successive collision. Both these cases allow the development of a mathematical model able to describe the relationship between apparent kinetics and individual collision events. However, the latter assumption seems to be more reliable than the former one, at least for commercial mills characterized by relatively complex displacement in the reactor (Manai et al., 2001, 2004).

A further obvious condition for the successful development of a mathematical description of MA processes is the one related to the uniformity of collision regimes. More specifically, it is highly desirable that the powders trapped at impact always experience the same conditions. This requires the control of the ball dynamics inside the reactor, which can be approximately obtained by using a single milling ball and an amount of powder large enough to assure inelastic impact conditions (Manai et al., 2001, 2004; Delogu et al., 2004). In fact, the use of a single milling ball avoids impacts between balls, which have a remarkable disordering effect on the ball dynamics, whereas inelastic impact conditions permit the establishment of regular and periodic ball dynamics (Manai et al., 2001, 2004; Delogu et al., 2004).

All of the above assumptions and observations represent the basis and guidelines for the development of the mathematical model briefly outlined in the following. It has been successfully applied to the case of a Spex Mixer/ Mill mod. 8000, but the same approach can, in principle, be used for other ball mills.

The Planetary ball mills are the most popular mills used in MM, MA, and MD scientific researches for synthesizing almost all of the materials presented in Figure 1.1. In this type of mill, the milling media have considerably high energy, because milling stock and balls come off the inner wall of the vial (milling bowl or vial) and the effective centrifugal force reaches up to 20 times gravitational acceleration.

The centrifugal forces caused by the rotation of the supporting disc and autonomous turning of the vial act on the milling charge (balls and powders). Since the turning directions of the supporting disc and the vial are opposite, the centrifugal forces alternately are synchronized and opposite. Therefore, the milling media and the charged powders alternatively roll on the inner wall of the vial, and are lifted and thrown off across the bowl at high speed, as schematically presented in Figure 2.17.

However, there are some companies in the world who manufacture and sell number of planetary-type ball mills; Fritsch GmbH (www.fritsch-milling.com) and Retsch (http://www.retsch.com) are considered to be the oldest and principal companies in this area.

Fritsch produces different types of planetary ball mills with different capacities and rotation speeds. Perhaps, Fritsch Pulverisette P5 (Figure 2.18(a)) and Fritsch Pulverisette P6 (Figure 2.18(b)) are the most popular models of Fritsch planetary ball mills. A variety of vials and balls made of different materials with different capacities, starting from 80ml up to 500ml, are available for the Fritsch Pulverisette planetary ball mills; these include tempered steel, stainless steel, tungsten carbide, agate, sintered corundum, silicon nitride, and zirconium oxide. Figure 2.19 presents 80ml-tempered steel vial (a) and 500ml-agate vials (b) together with their milling media that are made of the same materials.

Figure 2.18. Photographs of Fritsch planetary-type high-energy ball mill of (a) Pulverisette P5 and (b) Pulverisette P6. The equipment is housed in the Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR).

Figure 2.19. Photographs of the vials used for Fritsch planetary ball mills with capacity of (a) 80ml and (b) 500ml. The vials and the balls shown in (a) and (b) are made of tempered steel agate materials, respectively (Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR)).

More recently and in year 2011, Fritsch GmbH (http://www.fritsch-milling.com) introduced a new high-speed and versatile planetary ball mill called Planetary Micro Mill PULVERISETTE 7 (Figure 2.20). The company claims this new ball mill will be helpful to enable extreme high-energy ball milling at rotational speed reaching to 1,100rpm. This allows the new mill to achieve sensational centrifugal accelerations up to 95 times Earth gravity. They also mentioned that the energy application resulted from this new machine is about 150% greater than the classic planetary mills. Accordingly, it is expected that this new milling machine will enable the researchers to get their milled powders in short ball-milling time with fine powder particle sizes that can reach to be less than 1m in diameter. The vials available for this new type of mill have sizes of 20, 45, and 80ml. Both the vials and balls can be made of the same materials, which are used in the manufacture of large vials used for the classic Fritsch planetary ball mills, as shown in the previous text.

Retsch has also produced a number of capable high-energy planetary ball mills with different capacities (http://www.retsch.com/products/milling/planetary-ball-mills/); namely Planetary Ball Mill PM 100 (Figure 2.21(a)), Planetary Ball Mill PM 100 CM, Planetary Ball Mill PM 200, and Planetary Ball Mill PM 400 (Figure 2.21(b)). Like Fritsch, Retsch offers high-quality ball-milling vials with different capacities (12, 25, 50, 50, 125, 250, and 500ml) and balls of different diameters (540mm), as exemplified in Figure 2.22. These milling tools can be made of hardened steel as well as other different materials such as carbides, nitrides, and oxides.

Figure 2.21. Photographs of Retsch planetary-type high-energy ball mill of (a) PM 100 and (b) PM 400. The equipment is housed in the Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR).

Figure 2.22. Photographs of the vials used for Retsch planetary ball mills with capacity of (a) 80ml, (b) 250ml, and (c) 500ml. The vials and the balls shown are made of tempered steel (Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR)).

Both Fritsch and Retsch companies have offered special types of vials that allow monitoring and measure the gas pressure and temperature inside the vial during the high-energy planetary ball-milling process. Moreover, these vials allow milling the powders under inert (e.g., argon or helium) or reactive gas (e.g., hydrogen or nitrogen) with a maximum gas pressure of 500kPa (5bar). It is worth mentioning here that such a development made on the vials design allows the users and researchers to monitor the progress tackled during the MA and MD processes by following up the phase transformations and heat realizing upon RBM, where the interaction of the gas used with the freshly created surfaces of the powders during milling (adsorption, absorption, desorption, and decomposition) can be monitored. Furthermore, the data of the temperature and pressure driven upon using this system is very helpful when the ball mills are used for the formation of stable (e.g., intermetallic compounds) and metastable (e.g., amorphous and nanocrystalline materials) phases. In addition, measuring the vial temperature during blank (without samples) high-energy ball mill can be used as an indication to realize the effects of friction, impact, and conversion processes.

More recently, Evico-magnetics (www.evico-magnetics.de) has manufactured an extraordinary high-pressure milling vial with gas-temperature-monitoring (GTM) system. Likewise both system produced by Fritsch and Retsch, the developed system produced by Evico-magnetics, allowing RBM but at very high gas pressure that can reach to 15,000kPa (150bar). In addition, it allows in situ monitoring of temperature and of pressure by incorporating GTM. The vials, which can be used with any planetary mills, are made of hardened steel with capacity up to 220ml. The manufacturer offers also two-channel system for simultaneous use of two milling vials.

Using different ball mills as examples, it has been shown that, on the basis of the theory of glancing collision of rigid bodies, the theoretical calculation of tPT conditions and the kinetics of mechanochemical processes are possible for the reactors that are intended to perform different physicochemical processes during mechanical treatment of solids. According to the calculations, the physicochemical effect of mechanochemical reactors is due to short-time impulses of pressure (P = ~ 10101011 dyn cm2) with shift, and temperature T(x, t). The highest temperature impulse T ~ 103 K are caused by the dry friction phenomenon.

Typical spatial and time parameters of the impactfriction interaction of the particles with a size R ~ 104 cm are as follows: localization region, x ~ 106 cm; time, t ~ 108 s. On the basis of the obtained theoretical results, the effect of short-time contact fusion of particles treated in various comminuting devices can play a key role in the mechanism of activation and chemical reactions for wide range of mechanochemical processes. This role involves several aspects, that is, the very fact of contact fusion transforms the solid phase process onto another qualitative level, judging from the mass transfer coefficients. The spatial and time characteristics of the fused zone are such that quenching of non-equilibrium defects and intermediate products of chemical reactions occurs; solidification of the fused zone near the contact point results in the formation of a nanocrystal or nanoamor- phous state. The calculation models considered above and the kinetic equations obtained using them allow quantitative ab initio estimates of rate constants to be performed for any specific processes of mechanical activation and chemical transformation of the substances in ball mills.

There are two classes of ball mills: planetary and mixer (also called swing) mill. The terms high-speed vibration milling (HSVM), high-speed ball milling (HSBM), and planetary ball mill (PBM) are often used. The commercial apparatus are PBMs Fritsch P-5 and Fritsch Pulverisettes 6 and 7 classic line, the Retsch shaker (or mixer) mills ZM1, MM200, MM400, AS200, the Spex 8000, 6750 freezer/mill SPEX CertiPrep, and the SWH-0.4 vibrational ball mill. In some instances temperature controlled apparatus were used (58MI1); freezer/mills were used in some rare cases (13MOP1824).

The balls are made of stainless steel, agate (SiO2), zirconium oxide (ZrO2), or silicon nitride (Si3N). The use of stainless steel will contaminate the samples with steel particles and this is a problem both for solid-state NMR and for drug purity.

However, there are many types of ball mills (see Chapter 2 for more details), such as drum ball mills, jet ball mills, bead-mills, roller ball mills, vibration ball mills, and planetary ball mills, they can be grouped or classified into two types according to their rotation speed, as follows: (i) high-energy ball mills and (ii) low-energy ball mills. Table 3.1 presents characteristics and comparison between three types of ball mills (attritors, vibratory mills, planetary ball mills and roller mills) that are intensively used on MA, MD, and MM techniques.

In fact, choosing the right ball mill depends on the objectives of the process and the sort of materials (hard, brittle, ductile, etc.) that will be subjecting to the ball-milling process. For example, the characteristics and properties of those ball mills used for reduction in the particle size of the starting materials via top-down approach, or so-called mechanical milling (MM process), or for mechanically induced solid-state mixing for fabrications of composite and nanocomposite powders may differ widely from those mills used for achieving mechanically induced solid-state reaction (MISSR) between the starting reactant materials of elemental powders (MA process), or for tackling dramatic phase transformation changes on the structure of the starting materials (MD). Most of the ball mills in the market can be employed for different purposes and for preparing of wide range of new materials.

Martinez-Sanchez et al. [4] have pointed out that employing of high-energy ball mills not only contaminates the milled amorphous powders with significant volume fractions of impurities that come from milling media that move at high velocity, but it also affects the stability and crystallization properties of the formed amorphous phase. They have proved that the properties of the formed amorphous phase (Mo53Ni47) powder depends on the type of the ball-mill equipment (SPEX 8000D Mixer/Mill and Zoz Simoloter mill) used in their important investigations. This was indicated by the high contamination content of oxygen on the amorphous powders prepared by SPEX 8000D Mixer/Mill, when compared with the corresponding amorphous powders prepared by Zoz Simoloter mill. Accordingly, they have attributed the poor stabilities, indexed by the crystallization temperature of the amorphous phase formed by SPEX 8000D Mixer/Mill to the presence of foreign matter (impurities).

design documents (shaft couplings) | nbk | the motion control components

Perform calculations according to the following design procedure in order to select the proper shaft coupling. Design Procedure Calculate the Design Torque Select the Size Check the Maximum Shaft Hole Diameter and Maximum Rotation Speed Conclusion Selection ExampleMotor: Output 15 kW Standard motor (4-pole, 60 Hz), 1,750 min-1 Shaft diameter and key: 42, 12 x 8 Driven device: Centrifugal pump, operates 8 hours per day Shaft diameter and key: 35, 10 x 8 Calculate the Design TorqueSelect the overload factor Ko from [Table 1] and obtain the design torque. T 9550PNKo n T: Design torque (Nm) PN: Design power (kW) Ko: Overload factor [Table 1] n: Rotational frequency(min1) Design Torque Calculation ExampleAccording to [Table 1], overload factor Ko = 1.0 Therefore, Design torque T9550151.0 81.9Nm 1750 Select the SizeSelect a shaft coupling with a maximum torque (rated torque for Sure-Flex) that is equal to or greater than the design torque T from each performance table. Make sure to select the ideal shaft coupling type taking environment, cost, etc. into consideration. Size Selection ExampleHere, the flexible flanged shaft coupling is used. Since the design torque is 81.9 Nm, FCL-140 FCLS-140 are selected. Check the Maximum Shaft Hole Diameter and Maximum Rotation SpeedMake sure that both the maximum shaft hole diameter and the maximum rotation speed are not less than those of the design conditions. If either or both of the maximum shaft hole diameter and the maximum rotation speed do not satisfy the conditions, select a higher model number. Maximum Shaft Hole Diameter and Maximum Rotation Speed Checking ExampleThe maximum shaft hole diameter of FCL-140 is Bolt side: 38<42 (motor shaft diameter) Bushing side: 35=35 (driven device shaft diameter) so the design conditions are not satisfied. Using the same method, the max. shaft hole diameter of FCLS-140 is Bolt side: 42=42 (motor shaft diameter) Bushing side: 38>35 (driven device shaft diameter) so the design conditions are satisfied. The max. shaft hole diameter of the higher model number FCL-160 is Bolt side: 45>42 (motor shaft diameter) Bushing side: 38>35 (driven device shaft diameter) so the design conditions are satisfied. The maximum rotational frequency is FCL-160 4000min1 1750min1 FCLS-140 6000min1 1750min1 so the design conditions are satisfied. Therefore, either FCL-160 FCLS-140 will be used. ConclusionFinally, confirm that the design conditions are satisfied based on the dimensions/performance tables. Tables 3 and 4 are selection tables that are used when a general-purpose low-voltage three-phase squirrel-cage induction motor is the motor. The shaft coupling can be easily selected without relying on the above design steps. ConclusionFCL-160 FCLS-140 Use either of the above. [Table 1] Flanged shaft coupling overload factor: Ko Driven Device Motor Machine Used Electric motor or steam turbine Steam engine or 4-cylinder or more gasoline engine Diesel engine or gas engine Daily operating time (hours) 810 1624 810 1624 810 1624 Uniform load (no reverse rotation / low torque startup) Fluid mixer, centrifugal blowers/exhaust fan (up to 10PS), centrifugal pump, light-load conveyor, electric generator, worm gear reducer 1.0 1.5 1.5 2.0 2.0 2.5 Uneven load (no reverse rotation / normal shock) Conveyor, hoist, elevator, line shaft, hole mill, kiln 1.5 2.0 2.0 2.5 2.5 3.0 Heavy load with impact (with peak / with reverse rotation / full load startup) Reciprocating compressor, press, hammer mill, crusher, reciprocating pump, marine propeller 2.0 2.5 2.5 3.0 3.0 3.5 [Table 2] FCL (FC200) Selection Table 50Hz 2-pole2850min1 4-pole1425min1 6-pole950min1 8-pole725min1 Motor Rated Output kW Shaft Diameter mm Torque Nm Overload FactorKo Shaft Diameter mm Torque Nm Overload FactorKo Shaft Diameter mm Torque Nm Overload FactorKo Shaft Diameter mm Torque Nm Overload FactorKo 1.0 1.5 2.0 1.0 1.5 2.0 1.0 1.5 2.0 1.0 1.5 2.0 0.2 11 0.683 90 90 90 11 1.37 90 90 90 0.4 14 1.37 90 90 90 14 2.73 90 90 90 19 4.1 90 90 90 0.75 19 2.56 90 90 90 19 5.12 90 90 90 24 7.69 100 100 100 1.5 24 5.12 100 100 100 24 10.2 100 100 100 28 15.4 112 112 112 2.2 24 7.51 100 100 100 28 15 112 112 112 28 22.5 112 125 125 3.7 28 12.6 112 112 112 28 25.3 112 125 125 38 37.9 140 140 140 5.5 38 18.8 140 140 140 38 37.6 140 140 140 38 56.4 140 140 140 7.5 38 25.6 140 140 140 38 51.2 140 140 140 42 76.9 160 160 160 11 42 37.6 160 160 160 42 75.1 160 160 160 42 113 160 160 180 15 42 51.2 160 160 160 42 102 160 160 180 4855 154 180200 200 200 18.5 42 63.2 160 160 160 48 126 180 180 200 55 190 200 200 200 22 48 75.1 180 180 180 4855 150 180200 180200 200 5560 225 200224 200224 224 30 55 102 200 200 200 55 205 200 200 200 60 307 224 224 250 65 403 250 250 250 37 55 126 200 200 200 60 253 224 224 224 6065 379 224250 250 250 75 497 280 280 280 45 55 154 200 200 200 60 307 224 224 250 65 461 250 250 280 75 604 280 280 280 55 55 188 200 200 200 65 376 250 250 250 75 564 280 280 280 85 739 315 315 315 75 55 256 200 200 75 512 280 280 280 75 769 280 280 315 85 1010 315 315 315 90 55 307 200 224 75 615 280 280 280 85 922 315 315 315 95 1210 355 355 355 110 55 376 200 85 751 315 315 315 85 1130 315 315 315 95 1480 355 355 355 132 55 451 224 85 902 315 315 315 95 1350 355 355 355 160 55 547 95 1090 355 355 355 95 1640 355 355 355 200 55 683 95 1370 355 355 355 60Hz 2-pole3450min1 4-pole1750min1 6-pole1160min1 8-pole870min1 0.2 11 0.56 90 90 90 11 1.11 90 90 90 0.4 14 1.13 90 90 90 14 2.23 90 90 90 19 3.36 90 90 90 0.75 19 2.12 90 90 90 19 4.17 90 90 90 24 6.29 100 100 100 1.5 24 4.23 100 100 100 24 8.34 100 100 100 28 12.6 112 112 112 2.2 24 6.21 100 100 100 28 12.2 112 112 112 28 18.5 112 112 125 3.7 28 10.4 112 112 112 28 20.6 112 112 125 38 31.1 140 140 140 5.5 38 15.5 140 140 140 38 30.6 140 140 140 38 46.2 140 140 140 7.5 38 21.2 140 140 140 38 41.7 140 140 140 42 62.9 160 160 160 11 42 31 160 160 160 42 61.2 160 160 160 42 92.3 160 160 160 15 42 42.3 160 160 160 42 83.4 160 160 160 4855 126 180200 180200 200 18.5 42 52.2 160 160 160 48 103 180 180 180 55 155 200 200 200 22 48 62.1 180 180 180 4855 122 180200 180200 200 5560 185 200224 200224 200224 30 55 84.7 55 167 200 200 200 60 252 224 224 224 65 336 250 250 250 37 55 104 60 206 224 224 224 6065 311 224250 250 250 75 414 280 280 280 45 55 127 60 250 224 224 224 65 378 250 250 250 75 504 280 280 280 55 55 155 65 306 250 250 250 75 462 280 280 280 85 615 315 315 315 75 55 212 75 417 280 280 280 75 629 280 280 280 85 839 315 315 315 90 55 254 75 501 280 280 280 85 755 315 315 315 95 1010 355 355 355 110 55 310 85 612 315 315 315 85 923 315 315 315 95 1230 355 355 355 132 55 372 85 734 315 315 315 95 1110 355 355 355 160 55 451 95 890 355 355 355 95 1340 355 355 355 200 55 564 95 1110 355 355 355 Numbers in the table represent the size. The model number is displayed by adding "FCL" before these numbers. The shaft end dimensions depend on JEM1400-1991 (Dimensions of general-purpose low-voltage three-phase squirrel-cage induction motors). Numbers in parentheses indicate fully closed motors.

Design Procedure Calculate the Design Torque Select the Size Check the Maximum Shaft Hole Diameter and Maximum Rotation Speed Conclusion Selection ExampleMotor: Output 15 kW Standard motor (4-pole, 60 Hz), 1,750 min-1 Shaft diameter and key: 42, 12 x 8 Driven device: Centrifugal pump, operates 8 hours per day Shaft diameter and key: 35, 10 x 8 Calculate the Design TorqueSelect the overload factor Ko from [Table 1] and obtain the design torque. T 9550PNKo n T: Design torque (Nm) PN: Design power (kW) Ko: Overload factor [Table 1] n: Rotational frequency(min1) Design Torque Calculation ExampleAccording to [Table 1], overload factor Ko = 1.0 Therefore, Design torque T9550151.0 81.9Nm 1750 Select the SizeSelect a shaft coupling with a maximum torque (rated torque for Sure-Flex) that is equal to or greater than the design torque T from each performance table. Make sure to select the ideal shaft coupling type taking environment, cost, etc. into consideration. Size Selection ExampleHere, the flexible flanged shaft coupling is used. Since the design torque is 81.9 Nm, FCL-140 FCLS-140 are selected. Check the Maximum Shaft Hole Diameter and Maximum Rotation SpeedMake sure that both the maximum shaft hole diameter and the maximum rotation speed are not less than those of the design conditions. If either or both of the maximum shaft hole diameter and the maximum rotation speed do not satisfy the conditions, select a higher model number. Maximum Shaft Hole Diameter and Maximum Rotation Speed Checking ExampleThe maximum shaft hole diameter of FCL-140 is Bolt side: 38<42 (motor shaft diameter) Bushing side: 35=35 (driven device shaft diameter) so the design conditions are not satisfied. Using the same method, the max. shaft hole diameter of FCLS-140 is Bolt side: 42=42 (motor shaft diameter) Bushing side: 38>35 (driven device shaft diameter) so the design conditions are satisfied. The max. shaft hole diameter of the higher model number FCL-160 is Bolt side: 45>42 (motor shaft diameter) Bushing side: 38>35 (driven device shaft diameter) so the design conditions are satisfied. The maximum rotational frequency is FCL-160 4000min1 1750min1 FCLS-140 6000min1 1750min1 so the design conditions are satisfied. Therefore, either FCL-160 FCLS-140 will be used. ConclusionFinally, confirm that the design conditions are satisfied based on the dimensions/performance tables. Tables 3 and 4 are selection tables that are used when a general-purpose low-voltage three-phase squirrel-cage induction motor is the motor. The shaft coupling can be easily selected without relying on the above design steps. ConclusionFCL-160 FCLS-140 Use either of the above. [Table 1] Flanged shaft coupling overload factor: Ko Driven Device Motor Machine Used Electric motor or steam turbine Steam engine or 4-cylinder or more gasoline engine Diesel engine or gas engine Daily operating time (hours) 810 1624 810 1624 810 1624 Uniform load (no reverse rotation / low torque startup) Fluid mixer, centrifugal blowers/exhaust fan (up to 10PS), centrifugal pump, light-load conveyor, electric generator, worm gear reducer 1.0 1.5 1.5 2.0 2.0 2.5 Uneven load (no reverse rotation / normal shock) Conveyor, hoist, elevator, line shaft, hole mill, kiln 1.5 2.0 2.0 2.5 2.5 3.0 Heavy load with impact (with peak / with reverse rotation / full load startup) Reciprocating compressor, press, hammer mill, crusher, reciprocating pump, marine propeller 2.0 2.5 2.5 3.0 3.0 3.5 [Table 2] FCL (FC200) Selection Table 50Hz 2-pole2850min1 4-pole1425min1 6-pole950min1 8-pole725min1 Motor Rated Output kW Shaft Diameter mm Torque Nm Overload FactorKo Shaft Diameter mm Torque Nm Overload FactorKo Shaft Diameter mm Torque Nm Overload FactorKo Shaft Diameter mm Torque Nm Overload FactorKo 1.0 1.5 2.0 1.0 1.5 2.0 1.0 1.5 2.0 1.0 1.5 2.0 0.2 11 0.683 90 90 90 11 1.37 90 90 90 0.4 14 1.37 90 90 90 14 2.73 90 90 90 19 4.1 90 90 90 0.75 19 2.56 90 90 90 19 5.12 90 90 90 24 7.69 100 100 100 1.5 24 5.12 100 100 100 24 10.2 100 100 100 28 15.4 112 112 112 2.2 24 7.51 100 100 100 28 15 112 112 112 28 22.5 112 125 125 3.7 28 12.6 112 112 112 28 25.3 112 125 125 38 37.9 140 140 140 5.5 38 18.8 140 140 140 38 37.6 140 140 140 38 56.4 140 140 140 7.5 38 25.6 140 140 140 38 51.2 140 140 140 42 76.9 160 160 160 11 42 37.6 160 160 160 42 75.1 160 160 160 42 113 160 160 180 15 42 51.2 160 160 160 42 102 160 160 180 4855 154 180200 200 200 18.5 42 63.2 160 160 160 48 126 180 180 200 55 190 200 200 200 22 48 75.1 180 180 180 4855 150 180200 180200 200 5560 225 200224 200224 224 30 55 102 200 200 200 55 205 200 200 200 60 307 224 224 250 65 403 250 250 250 37 55 126 200 200 200 60 253 224 224 224 6065 379 224250 250 250 75 497 280 280 280 45 55 154 200 200 200 60 307 224 224 250 65 461 250 250 280 75 604 280 280 280 55 55 188 200 200 200 65 376 250 250 250 75 564 280 280 280 85 739 315 315 315 75 55 256 200 200 75 512 280 280 280 75 769 280 280 315 85 1010 315 315 315 90 55 307 200 224 75 615 280 280 280 85 922 315 315 315 95 1210 355 355 355 110 55 376 200 85 751 315 315 315 85 1130 315 315 315 95 1480 355 355 355 132 55 451 224 85 902 315 315 315 95 1350 355 355 355 160 55 547 95 1090 355 355 355 95 1640 355 355 355 200 55 683 95 1370 355 355 355 60Hz 2-pole3450min1 4-pole1750min1 6-pole1160min1 8-pole870min1 0.2 11 0.56 90 90 90 11 1.11 90 90 90 0.4 14 1.13 90 90 90 14 2.23 90 90 90 19 3.36 90 90 90 0.75 19 2.12 90 90 90 19 4.17 90 90 90 24 6.29 100 100 100 1.5 24 4.23 100 100 100 24 8.34 100 100 100 28 12.6 112 112 112 2.2 24 6.21 100 100 100 28 12.2 112 112 112 28 18.5 112 112 125 3.7 28 10.4 112 112 112 28 20.6 112 112 125 38 31.1 140 140 140 5.5 38 15.5 140 140 140 38 30.6 140 140 140 38 46.2 140 140 140 7.5 38 21.2 140 140 140 38 41.7 140 140 140 42 62.9 160 160 160 11 42 31 160 160 160 42 61.2 160 160 160 42 92.3 160 160 160 15 42 42.3 160 160 160 42 83.4 160 160 160 4855 126 180200 180200 200 18.5 42 52.2 160 160 160 48 103 180 180 180 55 155 200 200 200 22 48 62.1 180 180 180 4855 122 180200 180200 200 5560 185 200224 200224 200224 30 55 84.7 55 167 200 200 200 60 252 224 224 224 65 336 250 250 250 37 55 104 60 206 224 224 224 6065 311 224250 250 250 75 414 280 280 280 45 55 127 60 250 224 224 224 65 378 250 250 250 75 504 280 280 280 55 55 155 65 306 250 250 250 75 462 280 280 280 85 615 315 315 315 75 55 212 75 417 280 280 280 75 629 280 280 280 85 839 315 315 315 90 55 254 75 501 280 280 280 85 755 315 315 315 95 1010 355 355 355 110 55 310 85 612 315 315 315 85 923 315 315 315 95 1230 355 355 355 132 55 372 85 734 315 315 315 95 1110 355 355 355 160 55 451 95 890 355 355 355 95 1340 355 355 355 200 55 564 95 1110 355 355 355 Numbers in the table represent the size. The model number is displayed by adding "FCL" before these numbers. The shaft end dimensions depend on JEM1400-1991 (Dimensions of general-purpose low-voltage three-phase squirrel-cage induction motors). Numbers in parentheses indicate fully closed motors.

Select a shaft coupling with a maximum torque (rated torque for Sure-Flex) that is equal to or greater than the design torque T from each performance table. Make sure to select the ideal shaft coupling type taking environment, cost, etc. into consideration.

Make sure that both the maximum shaft hole diameter and the maximum rotation speed are not less than those of the design conditions. If either or both of the maximum shaft hole diameter and the maximum rotation speed do not satisfy the conditions, select a higher model number.

Using the same method, the max. shaft hole diameter of FCLS-140 is Bolt side: 42=42 (motor shaft diameter) Bushing side: 38>35 (driven device shaft diameter) so the design conditions are satisfied.

The max. shaft hole diameter of the higher model number FCL-160 is Bolt side: 45>42 (motor shaft diameter) Bushing side: 38>35 (driven device shaft diameter) so the design conditions are satisfied.

Finally, confirm that the design conditions are satisfied based on the dimensions/performance tables. Tables 3 and 4 are selection tables that are used when a general-purpose low-voltage three-phase squirrel-cage induction motor is the motor. The shaft coupling can be easily selected without relying on the above design steps.

Numbers in the table represent the size. The model number is displayed by adding "FCL" before these numbers. The shaft end dimensions depend on JEM1400-1991 (Dimensions of general-purpose low-voltage three-phase squirrel-cage induction motors). Numbers in parentheses indicate fully closed motors.

voltage gain characteristics of piezoelectric transformer using pbtio3 system ceramics - sciencedirect

PbTiO3 system ceramics were suitable to be used for a piezoelectric transformer, operating in thickness extensional vibration mode because these are materials with large anisotropy of electromechanical coupling factor, kt/kp. In this paper, the (Pb0.76Ca0.24)[(Co0.5W0.5)0.04Ti0.96]O3+1.5 mol% MnO2 ceramic system for piezoelectric transformers were manufactured. Its electromechanical coupling coefficients, kt of 49% and kp of near zero, which give rise to large anisotropic property, kt/kp, were obtained from the specimen sintered at 1150C. A piezoelectric transformer that is 20 mm long, 20 mm wide and 3.1 mm thick was fabricated using this composition ceramic. Resonant frequencies of second thickness extensional vibration mode are 1.56 and 1.58 MHz at loading resistance 100 and 200 , respectively. Maximum voltage gain of piezoelectric ceramics was 0.72 and 0.86 at resonant frequency of second thickness extensional vibration mode at loading resistance 100 and 200 [], respectively.

proper coupling selection: what you need to know

Santora: Hello and thank you everyone for attending todays webinar on proper coupling selection brought to you by Design World magazine. Without further ado, I will not turn it over to our first presenter, Randy Kingsbury.

Kingsbury: What Im going to do is share a little bit of what I learned through my 27 years in the applications engineering group. Consider the coupling a part of your design for your system early on. You cant believe how many phone calls we would have from people that would say, I have this system. Everythings great. Im hooking this motor to this shaft. I can do that We say, No problem. We can solve that. Then, they come back and say, Well, I also need it in stock and it needs to be delivered in the next three days because I forgot to plan for a coupling. With that said, please remember. Put it together, think about the coupling in the beginning, not as an afterthought when youre assembling.

There might be a few points that Ill bring up that are specific to Helical Products and our designs here but I do want to say that there many types of couplings. All of them have their benefit. All of them have some type of limitation. I would say that there is no perfect coupling that is the perfect answer for every application. Much of it comes down to researching the best coupling for your application when that time comes.

These couplings come in a variety of misalignments, torque capacities. The dimensions are all over the map. Some of them are very large in diameter for the amount of torque that theyre transmitting and then some of them are relatively small. Ill touch a little bit on materials later and give you some points to really think about as youre working on a new design and you need to consider material options.

One point to remember when youre selecting a coupling: theres no governing body for couplings in how theyre rated. Its not like the system that NEMA has for classifying motors and that type of thing. Its a best estimate or best calculation or the results of testing from each of the manufacturers.

When youre looking at the specifications for a coupling, make sure to read the data carefully. For example, one manufacture might list a torque rating and when you look at the footnotes, their torque rating is for static torque. Then you have another company like Helical Products where we use dynamic torque, where were rating our couplings based upon a high-cycle environment. We actually de-rate the coupling torque capacity based upon realizing that theyre going to be going through millions and millions of revolutions. Thats just a note to keep in mind as youre researching the different coupling. When an engineer is going into their coupling design specifications, these are some of the points that usually theyre pretty clear on. They know the shaft diameters, whether theyre connecting a motor to a lead screw or ball screw or some sort of positioning device or a pump shaft or something like that. Theyve usually selected those components ahead of time before they get to the coupling.

They key is, when theyre sizing their coupling or determining what size coupling they need, theyll be looking at torque. If an engineer is working with a positioning-type application, motion control, theyll also be thinking about what kind of torsional flexibility or torsional stiffness they need in their application. That will be a factor that they usually have some idea about. In a little bit, Im going to give you some more factors to consider when youre looking at torsional flexibility that maybe you havent thought about.

When you look at an assembly where youre putting a coupling in to connect a motor and shaft, theres two things to consider is in this case. Lets say you can see that theres 13 thousandths of offset. Lets say that as the engineer, you found this coupling that would be perfect for the application but it can only handle 5 thousandths of offset. It cost $50 per coupling. You find out this coupling, that will handle a 13 thousandths because it has more misalignment requirements is going to cost, lets say, 55 or $60.

One thing you have to think about: is it worth tightening up the tolerances on the parts that your machining to warrant getting a coupling with less misalignment capability? Thats just a general point to keep in mind. How tight do you hold your tolerances on machine parts? It does cost money to hold tighter tolerances, but is it easier to get a coupling with a little bit more misalignment and stay with relatively standard tolerancing? Thats a consideration when youre going into a design.

Another example of a more common type of misalignment is angular. Angular is measured as the angle between two shafts, where collinear center lines would be ideal. Parallel offset- center lines are parallel but theres some distance of offset. Generally, couplings do a pretty good job at 10 thousandths and below of offset. Once you start hitting 20 thousandths or more of offset, youre going to have a harder time finding a coupling thats going to fit and a relatively compact package.

The other thing is, if you find a coupling that has a large parallel offset capability, be sure and check what its RPM, or speed rating, is because usually when they handle extremely large offset, some of the designs are limited in what they can handle as far as RPM.

This is actually an operational consideration when we look at axial motion. In our catalog, we actually call it a misalignment but this is a situation where we invited the engineers not considering these things during a design and that one common source of axial motion can be thermal expansion as a machine device is running, heating up or if its in an environmental condition that heats up and cools down, there can actually be some relative movement between the shafts that are being connected. The reason this is important is because not all coupling solutions are capable of having axial compliance. Theyre rigid in the axial direction. What that can do is put a lot of load onto the bearings in a motor. The same with thrust loading. If youve got a motion control system and you have a little bit of replay in your lead screw but you have a thrust bearing in there, if you have an axially-rigid couplings, youre not going to be putting the load to the thrust bearing in your bearing blocks. Youre actually going to be transmitting it to the motor.

When youre thinking about environmental conditions, you have to think temperature. Many people think its just how hot something gets but another consideration is how cold. There can be conditions where an elastomeric item could see some extremely cold temperatures. Perhaps in a space environment, that could be a major problem, obviously. For us, temperature wise, once we hit 200, the strengths of our aluminum coupling really drops off. Our ratings go lower. Thats why we have a high strength 17-4 coupling available.

The other thing to consider when youre looking at the temperature aspect is not only whether its hot or cold but how large is the temperature swing. Some of that goes back to thermal expansion and axial motion.

The second point to consider is chemical. Is it a harsh environment? Is it a very corrosive atmosphere? Weve done a lot of work here with a material called MP35N thats used in a very harsh, downhole environment. Be sure to consider what materials are going to be exposed to. Will it be in salt water? If its near the ocean or shipboard, you might need a special material or a titanium. Also, if youre in an environment that requires washdown, do you need something thats going to be safe from corrosion? Is it near food?

Another consideration, is if youre in the medical field. I dont know if it applies to much to the coupling but we do some springs that are medical implant devices. There, you would need a unique material but also, if youre doing a coupling thats in either a piece of medical equipment or a tool thats actually used in surgery, you might need a special material that can handle the temperature of autoclaving and sterilizing.

As youre in an application like that, the case of torque may not be the only consideration. It might come down to more importantly what kind of temperature is it going to be cleaned at when its sterilized? .

Moving on. Think about speed, RPM. Certain applications are relatively easy to solve with most any coupling at 5,000, maybe up to 10,000 RPM. Occasionally, you get up into 25,000 RPM. Weve run into applications that are up into 75,000, 80,000 RPM. The consideration youll need to factor in there is again, not just torque capacity but how well balanced is the coupling for that type of speed because if its not either a balanced coupling or design thats symmetrical by nature, that makes it a statically balanced part, youre going to be running into a vibration situation due to the imbalance of the weight. Thats an important consideration. We run into that more and more as these positioning devices are accelerating faster and faster.

More considerations. As youre starting to see, a lot of thought needs to go into a coupling because theres a lot of factors here. I Want to point out some of the more common attachments that we run into and I think most coupling manufacturers work with. First and foremost is a set screw. People often think of these because theyre relatively low cost. The problem with a set screw is itll leave a burr on your shaft and can cause some problems there. Really, if youre using a set screw attachment, you want to be sure and at least one of the set screws is being set down onto a flat. One thing we dont recommend is using a set screw attachment in a motion control type environment because when its reversing and those loads are reversing, the set screw will actually loosen up. Some people try to compensate for that with a keyway. That can help, especially with preventing the set screw from loosening.

Far and away the most common method of attaching a shaft to the coupling is what we call the clamp attachment. The middle is a single-piece coupling where we actually machine the clamp into the part. The lower one is a removable cap. The reason why you would want a removable cap is because it allows you to undo two cap screws on the one side. Then, the cap comes off and you can just pull the coupling straight out without moving your motor or your shaft or any of those mating components apart. Thats the reason for the removable cap.

Collins: Hi. Thanks, Mike. Thanks, Randy. My names Rob Collins. I work here at Servometer as a technical support engineer for the past 5 years. Hopefully, I can share a little bit of knowledge as to what we have available.

The things I want to discuss are the Servometer bellows coupling construction, standard and custom bellows coupling that are available. Examples of applications, pitfalls of proper coupling selection, geometry, torque, flexibility, mutual exclusivity of properties for bellows couplings, the operational environments and the guidelines for specifying a custom design.

Bellows couplings are an assembly of two end pieces onto an electrodeposited nickel metal bellows. The bellows is fabricated using electrodeposition of nickel onto an aluminum mandrel. This is achieved by starting with an aluminum stock. We then machine the aluminum mandrel to have the internal dimension of the bellows. Then the aluminum mandrel is plated with electrodeposited nickel called FlexNickel. Once plated, the nickel is cut to define the ends of the bellows and expose the aluminum under the nickel.

Finally, the aluminum is removed chemically, leaving behind the nickel metal bellows. The finished nickel metal bellows can also be plated with gold, silver or copper for enhanced corrosion resistance or electrical conductivity.

Standard bellows couplings are not stored as finished products ready to ship. However, the varied hub sizes and the bellows are stocked such that orders for most sizes can be assembled and shipped within one to two weeks of ordering, depending on the quantity required.

From stock, we have many couplings available with sizes ranging from a 1/4 to 2.4-in. in diameter and from 0.48 up to 2.4-in. long with bore sizes as small as 2 mm and all the way up to 1-in. in diameter.

Standard bellows couplings are suitable for service where the application temperature will vary from anywhere from -58 up to 260 F and applications such as resolvers and small actuators and motors. The temperature limitation for standard bellows couplings are limited due to the fact that the assembly is done with epoxy to bond the end pieces onto the bellows. Bellows couplings excel where the applications demands zero backlash, low windup and high torsional stiffness. The 100,000,000 cycle life will apply provided that the coupling is not used beyond its rated limits of compression, vending and offset. Further to this, it is important to note that these properties are mutually exclusive.

Servometer can provide custom units with varied capabilities above and beyond the previous mentioned limits such as nearly any bore size can be accommodated, unique flanges or end pieces can be attached to the bellows. Unique combinations of compression bending and offset with given torque and windup requirements can be achieved. Higher torque than 4,000 inch ounces is certainly possible and an operating temperature as high as 300 F are possible and temperature less than -58 F are feasible with a custom bellows coupling.

Increased and decreased temperature ratings would be achieved by assembling with an 95/5 tin silver solder. Naturally, a guaranteed cycle life will not be feasible at significantly lower temps such as cryogenic without testing. However, we do have bellows couplings operating in millikelvin experiments in quite a few different places. Theyre certainly feasible to use for low temperature applications.

Servometer bellows couplings are used in many varied applications spanning industries such as medical, semiconductor, aerospace and military, among others. In the medical field, our bellows couplings are used for manipulating microscope stages, x-ray view boxes and other equipment such as dosing pumps. In the semiconductor field, the bellows coupling are used for position indication of lead screws, pick and place machines and other varied chip manipulation equipment. In aerospace and military field, the bellows couplings are used for adjusting targeting mirrors and lenses. Their lightweight construction helps them find service with instrumentation knobs inside and outside of the cockpit of an aircraft.

Also, on one very special application, with the M1 Abrams Tank, a Servometer bellows coupling assists with the main tank gun barrel system that allows it to remained aimed on target regardless of the changing position of the tank when moving.

Id like to share with you some of the pitfalls of proper bellows coupling selection. Many people will call and give us geometry and think that the geometry of the coupling is all that matters but this isnt true. The overall size of a bellows coupling does not necessarily indicate that it is suitable for the application. Many might assume that if they provide general envelope dimensions, that the allowable torque and the amount of compression and other properties would just fall on the line and be appropriate for their application but this is not the case. Geometry may limit the selection of available coupling from our stock offering but it does not guarantee the proper function of the coupling in service. If it is known that we are replacing a Servometer stock coupling that had a suitable service life with another Servometer stock couplings, then geometry will certainly help to determine a replacement. However, Servometer can make two bellows that look exactly the same act very differently just by changing the wall thickness by a thousandths of an inch or so.

Another poor assumption is that the torque requirements will match the bore size but 3/8-in. shaft can handle much more torque than most Servometer coupling yet we offer larger bore sizes to match motors or shaft sizes that are used for lower torque applications such as that of a resolver. The size of the bore on a bellows coupling does not indicate that it is capable of handling as much torque that a shaft of the mating size might deliver.

Another poor assumption is that the last bellows coupling broke so higher torque or a different design is required. Cycle life is not related to torque but it is related to one rotation is equal to two cycles. The amount of compression offset or bending that is used at any one time and not just during operation will affect the cycle life.

No excursions can be allowed when considering life cycles. No allowance is made for over-compression or offset during installation and maintenance and down time. During these times, it is important to emphasize that the bellows can and will flex much more than what it was rated for on paper for the application. However, the rating applies to a reduced flexure to allow for the long cycle life that is specified and/or desired.

Some other pitfalls are in the operational environment similar to what Randy was stating. Its important to consider that temperature, vibration, corrosion, these can all cause unique problems for good bellows coupling application and they can certainly be overcome if appropriately specified.

Speed of operation is important. For example Servometer bellows coupling are not speed balanced. If high speed greater than 3,000 RPM is required, then a third-party might need to be contacted to balance the coupling as you will require. It is also useful to note that the hubs are not in alignment with each other. If special alignment is required, then a custom design will be needed to support your application.

A lot of people wrongly assume they dont have enough time for a custom design. The time invested in detailing the necessary performance characteristics of your application will pay off many dividends if done in advance. Theres a situation of paying down the time required now or after repeated failures due to a lack of planning.

Next, I want to just go over some geometry considerations. The design envelope will restrict how much selection you can have from readily available stock bellows. The outside diameter is another potential problem but can potentially be solved with a custom unit if considered. The thicker wall bellows might handle higher torque requirements than a same size bellows with a smaller overall diameter. Other performance requirements such as compression, offset and bending may suffer accordingly with an increase in wall thickness.

Sometimes, the stock unit can be quickly modified to accommodate a thicker wall. However, there are limits to how much thicker any one design can become and a custom unit may be designed for a thicker wall.

One simple solution not to be overlooked is that the bellows couplings are hollow and the shaft can protrude into the bellows cavity providing that does not interfere with the bellows wall. That screw-style bellows coverings are shorter by nature than compared to an integral clamping hub style. Generally speaking, set screws are typically more than sufficient for most applications using a bellows coupling as the allowable torque is not particularly high. Sometimes, a larger diameter can allow for more flexibility in a shorter bellows. Naturally, there are limits but if necessary, a custom larger diameter unit may be designed to accommodate a limited length application.

Torque requirements are also another major concern, of course, when considering a bellows coupling. The torque of the motor, though, is not the maximum torque of the system. Gearboxes act like a torque multiplier. If a coupling is used on the output shaft of a gear box, then the torque of the motor multiplied by the speed ratio may be a good starting point for determining your torque requirement.

The starting torque of the motor may be three to five times that of the operational torque of the system. It is important to consider the moment of inertia of the system when determining the maximum torque requirement of the coupling. When bellows couplings are used in compression, only 75% of the torque ratings should be used, since there is a potential for that bellows to buckle.

Buckling of bellows is similar to that of an overloaded column, in that it occurs when it is unpredictable in movement and likely increased windup, hence a bellows experiencing buckling will not provide reliable movement. Pulleys must also be considered to calculate the proper maximum instantaneous torque required for a bellows coupling. This similar to that of a gear box, however, with a pulley system, the value of the torque may increase or decrease, depending on its placement in the system.

The flexible movement considerations are also of interest, particularly with a flexible bellows coupling. Compression offset and bending are mutually exclusive. The percentage of each movement used with respect to its maximum when added together must be less than 100% or the bellows cycle life will be less than the standard 100,000,000 cycles.

Again, it is important to note that the bellows is much more flexible than that rated on the drawing or catalog, since it can easily move more than the values listed on the drawing, any movement beyond these limits will reduce the cycle life of the bellows accordingly.

The operational environment is of natural concern. 260 F is the maximum operating temperature of a standard bellows coupling. There is a maximum operating temperature of 350 for a Servometer bellows alone. The bellows limiting temperature is due to the fact that above this temperature, the bellows will start to anneal. If the material anneals, then it will lose its temper and not respond like a bellows or spring any longer.

The minimum operating temperature of the bellows is not necessarily a known hard value. There are customers using Servometer bellows in millikelvin temperature experiments with custom units. The bellows do operate acceptably in this environment, however the minimum operating temperature of a Servometer standard coupling is minus 58 F. This is due to a physical limitation of the epoxy used for assembly.

Corrosion resistance is also of concern. Servometer bellows coupling are an assembly of one bellows with 2 hubs that attach onto the shafts. The bellows is comprised of Servometer nickel and is similar to that of nickel 200 alloy. The hubs are fabricated from 303 stainless steel. Aluminum hubs are also a potential supply for applications that require an extremely lightweight option. Naturally, many other materials for the hubs can be made available with a custom unit.

Now, I want to give you some guidelines for determining what you need for a custom design. Custom couplings with diameters as large as 9-in. in diameter and as long as 18-in. are possible for Servometer. In order to develop a custom design, we will need input on the following items to be best determine how to proceed. The temperature of operation for these couplings could be as high as 300 F and as low as minus 423 F for a custom design. Again, we know of customers using these bellows in millikelvin research. There isnt a necessarily hard known value for lower temperature limit.

Corrosion protection of the bellows coupling may be enhanced with gold, silver or even copper plating if required for different environments in applications such as to maintain electrical conductivity. The type of movement required is one of the most important aspects to consider to create a design that will meet the cycling demand of the application.

The maximum torque must be determined based on how the coupling will be connected in the system and whether the system contains any gearboxes, motors and pulleys. Speed of rotation is important mainly for high speed applications, a special consideration may be required for balancing the coupling in the system.

In summary, we discussed the standard of custom. It really does depend on your requirements. If the application is straightforward and you only need bending or offset, then perhaps a standard unit may fit the bill. However, if many of the properties available are used or you require custom end pieces or specific spring rate, then a custom unit is most likely going to be required.

Know your geometry. Space limitations may determine for you what might be readily available from the standard bellows couplings but if you require a custom coupling, we mostly likely can overcome just about any space limitations you have. Larger diameters help carry higher torque allowances. Remember, the bellows coupling is hollow inside. If tight spaces demand that the shaft protrudes into the bells, it certainly can accommodate that.

Torque requirements. Naturally knowing how much torque is required is important but flexibility may also be just as demanding. Keep in mind the various torque multipliers that come into play for your project. Flexibility requirements, mutual exclusivity must be understood to prevent the potential of early failure for the bellows coupling. If all of one property is being used at one time, then you dont have the other properties available anymore. Even the smallest amount of those other properties could exceed the rating of the bells and naturally, a lower cycle life should be expected.

Of course, its always nice to have a little bit more compression offset in bending available to allow for unaccounted or unintended movements such as when these parts are being placed into installation.

Operational environment, maximum temperature of 260 F and a minimum temperature of -58 F for standard bellows which are epoxied. Consider materials of construction. Bellows material is nickel and the end pieces are 303 stainless steel. If in doubt, ask about your specific environmental requirements.

Custom bellows coupling can overcome many challenges that would disqualify using a standard bellows. If the necessary details are understood and specified early, its likely that a good solution can be developed. Thank you for your time.

Santora: Thanks, Rob. Were going to open it up now for questions. Were going to get to as many as we can but of course just remember that whatever we dont get to during the webinar, youll be able to email Randy and Robert. First question:Whats a good first step for coupling selection?

Kingsbury: Probably the easiest way I think of for somebody starting is most of the coupling manufacturers currently have a coupling selector on their website. Ive given you a screenshot of one that we have. I would say thats probably a good spot. If you have some really extreme conditions, I would just call them. I think all the key players have applications. Engineerings waiting to answer questions.

Kingsbury: Again, it comes down to the torque and torsional flexibility. It depends on many factors as I was mentioning. We have what are called multi-start couplings that give high torsional stiffness. In extreme cases, weve sent engineers to Servometer because the bellows coupling has a tremendous amount of torsional stiffness which is part of what effects your positioning accuracy on a fast-moving system. When youre looking at a fast moving application, you want a product that has no backlash. When you get into coupling that are multiple pieces, you have the potential of getting into a backlash system which can make the positioning a real problem to compensate for.

Kingsbury: No. A lot of our couplings, I certainly know in the ones we do at Helical, its really for the most part, when you get that 5 5/8th diameter and above is when the coupling within the keyways become relatively common. Some people go down to half inch but if you get smaller, expensive to make and really, the clamp has more than enough torque capacity to transmit the load.

Kingsbury: Wow! Yes. Ill throw in my 2 cents. Really, a lot of the couplings. I know Servometer will be essentially constant velocity when youre running at a constant load. The types that wont are a type of coupling called a Cardan-style u joint. Its where, as the angle gets larger, the variation between the input speed and the output speed oscillate. Unless you put them together in pairs and phase them properly, you will not have constant velocity. Especially in motion control, that can be a real problem. I dont know if Rob has some thoughts on that.

Collins: I think you hit the nail on the head. Its similar to your previous comment in that if its composed of multiple pieces, then its much more likely to be similar to backlash to have the potential for stored energy in the system than to actually have the ends rotating at slightly different speeds but otherwise, everything weve discussed really are constant velocity.

Santora: Okay, gentlemen. I think were going to try to squeeze in one last question here. Then, well start wrapping things up. Question coming in. For a coupling with clamp-style fasteners, does the fastening torque matter or will it affect the functioning of the coupling? What if each side is tightened unequally?

Kingsbury: Ill start and then get Robs input on that. The tightening torque absolutely makes a difference on the fastener. When you have a clamp and there is friction between the clamp and the shaft from tightening that cap screw- that transmits torque. I think most of the coupling manufacturers will give a recommended tightening torque which is basically the rating of the cap screw, typically. You definitely want to use everything you can to make sure its on there firmly and transmits the torque without slippage.

Collins: Yes. I agree again, Randy. I cant think of any reason why you would want the uneven tightening of either end. The whole idea is to transfer that rotational movement from one end to the other. If theyre not tightened evenly, theyre certainly leads to problems of slip. Its also possible they wouldnt be tightened evenly if there were 2 different shaft sizes. That goes back to the cap screw size that was used for the clamp, as you mentioned. Otherwise, in the ideal world where both sides of the coupling are the same size, then I would think they should be evenly tightened.

Copyright 2021 WTWH Media LLC and its licensors. All rights reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media.

inch to metric servo couplings | ruland

Due to Microsoft's discontinuation of updates, including security, certain functionality such as checkout and CAD may not work for you. We recommend using Google Chrome, Microsoft Edge, Firefox, or Safari to ensure full functionality.Thank you - the Ruland team

This Ruland bundle combines a one or two-piece shaft collar with a clamping lever to make a quick release shaft collar. Bore sizes range from 3/8 to 1 and 11mm to 40mm. Collars are available in anodized aluminum, plain aluminum, 303 stainless steel, 316 stainless steel, steel, plastic, and zinc..

The patented slit design has radiused edges that reduce stress on the coupling allowing for high misalignment and torsional stiffness with low bearing loads. Ruland stocks and bores to size slit couplings in bore sizes ranging from 1.5mm to 12mm or 1/8 to 3/8.

Motion systems often utilize a servo or stepper motor with metric shafting driving a ball screw, lead screw, or encoder with inch shafting. Matching application parameters to a motion control coupling can be a challenging task which becomes more difficult when inch to metric bore combinations are required. Ruland now stocks a full range of motion control couplings with inch to metric bores including beam, bellows, curved jaw, disc, and oldham types. Motion control couplings from Ruland are zero-backlash for accuracy of motion and are manufactured in our Marlborough, MA factory.

Choosing the correct servo coupling can be a difficult process that involves many performance factors including: shaft misalignment, RPM, space restrictions, torque, and others. Motion control couplings from Ruland are available in a wide variety of styles, sizes, and materials to match application requirements critical to system performance. For more information about the differences between each coupling see below.