how toggle joint mechanism is used in crushing of lime stone

oil type double toggle jaw crusher at best price in sabarkantha gujarat from labh engineering works | id:4326829

This product is widely applied in middle and fine crushing of all kinds of ore, cement, refractory material, aluminum oxide grog, carborundum, glass raw material and other high hard and super hard material; as well as fine crushing of water, power, road, building, cement and metal mine industry. Double toggle jaw crusher : jaw crusher are preferably used at primary and second crushing of non-sickly medium hard and hard rock like granite, be salt, lime stone, etc. double toggle oil type jaw design has been focused to decreasing maintains cost and demands and to increasing their rascality and cutting operation costs sampling of an automatic grease lubrication a started. Oil type double toggle : The body is welded robust steel construction, very string and yet very light. Jaw crusher of LION crusher last longer as compared to jaw plates to the jaw plates of other crusher because LION jaw crusher work on the principle of Crushing without rubbing for different application suitable jaw plates are available and these can be fitted to the crusher without any difficulty. In LION jaw crusher automatic, continuous spray lubrication by positive gear pump for the pitman toggle mechanism enables the crusher to ruse safety. In LION jaw crusher massive rigid eccentric shaft of special steel is carried in sift aliened spherical roller bearings of ample capacity which ensures easily started with a normal duty squirrel cage motor. LION crusher have light-weight pitman having white metal lining for bearing surface which prevents excess friction. Double toggle, for even the smallest size crusher give even distribution of load. Well designed compression springs provide crushing to the toggle mechanism which Eli- mate knock and reduce the resultant wear. In LION crusher, strong hinge pin of special steel is located in connect relation to the crushing zone for crushing without rubbing. Its with specially designed oil resistant flexible diaphragm seals the opening in the oil chamber and protects the mechanism against dust.

This product is widely applied in middle and fine crushing of all kinds of ore, cement, refractory material, aluminum oxide grog, carborundum, glass raw material and other high hard and super hard material; as well as fine crushing of water, power, road, building, cement and metal mine industry.

jaw crusher are preferably used at primary and second crushing of non-sickly medium hard and hard rock like granite, be salt, lime stone, etc. double toggle oil type jaw design has been focused to decreasing maintains cost and demands and to increasing their rascality and cutting operation costs sampling of an automatic grease lubrication a started.

The body is welded robust steel construction, very string and yet very light. Jaw crusher of LION crusher last longer as compared to jaw plates to the jaw plates of other crusher because LION jaw crusher work on the principle of Crushing without rubbing for different application suitable jaw plates are available and these can be fitted to the crusher without any difficulty. In LION jaw crusher automatic, continuous spray lubrication by positive gear pump for the pitman toggle mechanism enables the crusher to ruse safety. In LION jaw crusher massive rigid eccentric shaft of special steel is carried in sift aliened spherical roller bearings of ample capacity which ensures easily started with a normal duty squirrel cage motor. LION crusher have light-weight pitman having white metal lining for bearing surface which prevents excess friction. Double toggle, for even the smallest size crusher give even distribution of load. Well designed compression springs provide crushing to the toggle mechanism which Eli- mate knock and reduce the resultant wear.

In LION crusher, strong hinge pin of special steel is located in connect relation to the crushing zone for crushing without rubbing. Its with specially designed oil resistant flexible diaphragm seals the opening in the oil chamber and protects the mechanism against dust.

toggle mechanism | machine part | britannica

Toggle mechanism, combination of solid, usually metallic links (bars), connected by pin (hinge) joints that are so arranged that a small force applied at one point can create a much larger force at another point. In the Figure, showing a toggle mechanism at work in a rock-crushing machine, the numbered links are pin-connected at A, B, C, D, and E. Rotation of link 1 about the fixed pivot A causes the block to slide back and forth. The relation between the force in link 2 acting at C and the force W exerted on the block at D, and thus on the rock, depends on the angle symbolized by the Greek letter theta, ; the smaller the angle, the greater is W in terms of F. For equal to one degree, W is nearly 29 times F. Toggle mechanisms are used to obtain large force amplification in such applications as sheet metal punching and forming machines. See also linkage.

analysis of the single toggle jaw crusher force transmission characteristics

Moses Frank Oduori, David Masinde Munyasi, Stephen Mwenje Mutuli, "Analysis of the Single Toggle Jaw Crusher Force Transmission Characteristics", Journal of Engineering, vol. 2016, Article ID 1578342, 9 pages, 2016. https://doi.org/10.1155/2016/1578342

This paper sets out to perform a static force analysis of the single toggle jaw crusher mechanism and to obtain the force transmission characteristics of the mechanism. In order to obtain force transmission metrics that are characteristic of the structure of the mechanism, such influences as friction, dead weight, and inertia are considered to be extraneous and neglected. Equations are obtained by considering the balance of forces at the moving joints and appropriately relating these to the input torque and the output torque. A mechanical advantage, the corresponding transmitted torque, and the variations thereof, during the cycle of motion of the mechanism, are obtained. The mechanical advantage that characterizes the mechanism is calculated as the mean value over the active crushing stroke of the mechanism. The force transmission characteristics can be used as criteria for the comparison of different jaw crusher mechanism designs in order to select the most suitable design for a given application. The equations obtained can also be used in estimating the forces sustained by the components of the mechanism.

The literature on kinematics and mechanism design identifies three tasks for which linkage mechanisms are commonly designed and used, namely, function generation, motion generation, which is also known as rigid body guidance, and path generation [13]. Way back in 1955, Freudenstein, who is widely regarded as the father of modern Kinematics of Mechanisms and Machines, introduced an analytical method for the design of a four-bar planar mechanism for function generation [4]. Wang et al. presented a study on the synthesis of planar linkage mechanisms for rigid body guidance [5]. An interesting design and application of a planar four-bar mechanism for path generation was reported by Soong and Wu [6]. In general, the use of linkage mechanisms involves the transmission and transformation of motions and forces. In practical applications, linkage mechanisms appear to be more commonly designed and used for the transmission and transformation of motions rather than forces. In such cases, the transmitted forces are quite small.

The jaw crusher happens to be an example of a planar linkage application that is designed and used for the transmission and transformation of motions but also has to transmit, transform, and apply the large forces that are required to crush hard rocks by compression. Therefore it is important to understand the force transmission characteristics of the jaw crusher mechanism and to be able to use them for sound mechanical design of the crusher.

Today, the most commonly used types of jaw crusher are the single toggle and the double toggle designs. The original double toggle jaw crusher was designed by Eli Whitney Blake in the USA in 1857 [7]. The motion of the swing jaw in a double toggle crusher is such that it applies an almost purely compressive force upon the material being crushed. This minimizes wear on the crushing surfaces of the jaws and makes the double toggle jaw crusher suitable for crushing highly abrasive and very hard materials. Even today, the Blake design, with some comparatively minor improvements, can still be found in mines and quarries around the world.

The single toggle design, which was developed between the 1920s and the 1950s, is a simpler, lighter crusher [7]. Its swing jaw has a rolling elliptical motion such that it applies a compressive as well as a rubbing force on the material being crushed. This has a force-feeding effect that improves the throughput of the device, but it also tends to cause rapid wear of the crushing surfaces of the jaws. However, the single toggle jaw crusher has a lower installed cost, as compared to the double toggle design. Improvements in materials and design have made the single toggle jaw crusher more common today as the primary crusher in quarrying operations [8]. According to Carter Russell [9], in 1999 sales of the single toggle jaw crusher exceeded those of the double toggle jaw crusher by a factor of at least nine to one.

This paper performs a static force analysis of the single toggle jaw crusher mechanism. As a result of this analysis, a characteristic force transmission ratio, which may be regarded as a mechanical advantage of the mechanism, is derived. This ratio can be used as a criterion for the comparison of different jaw crusher mechanism designs, with a view to selecting the most suitable design for use in a given application.

Over time, several authors have addressed the static force analysis of the double toggle jaw crusher mechanism. Among the earlier of such efforts is that of Ham et al. [10], who performed a static force analysis of the double toggle jaw crusher mechanism in order to determine the input turning moment that would be required to overcome a known crushing resistance of the material being crushed. They used a graphical method to carry out the analysis.

In discussing linkages, Martin [11] featured the double toggle jaw crusher mechanism as an example of a machine that uses the toggle effect to obtain a large output force that acts through a short distance, but he did not perform a static force analysis of the mechanism.

Erdman and Sandor [1] presented the determination of the mechanical advantage of a double toggle jaw crusher mechanism, as an exercise problem to be solved by(1)the method of instant centres, which is essentially a graphical method;(2)an analytical method that utilized complex number representation of vectors.Norton [2] also discussed the mechanical advantage of linkage mechanisms and explained the toggle effect by the use of a jaw crusher mechanism of the Dodge type [8].

More generally, Lin and Chang [12] addressed the issue of force transmissivity in planar linkage mechanisms. They derived and proposed a force transmissivity index (FTI) that considered the power flow path from the input linkage to the output linkage. They calculated the effective force ratio (EFR) as the ratio of the sum of actual power transmitted at each of the linkage joints in the power flow path to the sum of the maximum possible power that could be transmitted along the same power flow path. They then obtained the FTI as the product of the EFR and the mechanical advantage of the mechanism, thus taking into account the effect of the external load acting on the mechanism. They compared their results to other indices of force transmissivity, such as the Jacobian matrix method [13] and the joint force index (JFI) [14], and found their FTI to be more accurate. Furthermore, the Jacobian matrix method does not consider the effect of the external load while the JFI does not consider the power flow path in the mechanism.

The method used by Lin and Chang [12] involves a static force analysis and the determination of velocities at the joints within the power flow path. Subsequently, Chang et al. [15] extended and applied this method to parallel manipulators, defined, and proposed a mean force transmission index (MFTI). The presentation here will perform a static force analysis and obtain the mechanical advantage of the single toggle jaw crusher mechanism, from first principles.

According to Ham et al. [10], analysis of forces in any machine is based on the fundamental principle which states that the system composed of all external forces and all the inertia forces that act upon any given member of the machine is a system that is in equilibrium.

For a planar mechanism, such as the single toggle jaw crusher, it is customary to treat the forces as if they are coplanar, at least in the initial analysis. The effects of the offsets between the planes of action of the forces can then be revisited at a later stage of analysis and design. The assumption of coplanar forces will be employed in this presentation.

In the static force analysis of a machine, the forces arising due to the accelerations of the machine members are neglected. These forces are taken into account in a dynamic force analysis, which can be done, meaningfully, after the forms and masses of the machine members have been determined. Frictional forces may be taken into account in a static force analysis [16], but in the present case, it shall be assumed that the use of antifriction bearings in the revolute joints reduces frictional forces to negligible levels.

Furthermore, this presentation aims to obtain an indicator of the efficacy of force transmission, in the single toggle jaw crusher, that may be attributed to the structure of the mechanism per se. Therefore, frictional and inertia forces may be regarded as extraneous to this purpose and will not be included in this analysis.

In a planar four-bar mechanism with four revolute joints, which can be denoted by or , the efficacy of force transmission has often been expressed by what is known as the transmission angle [2, 3, 11, 17]. This works well enough if, for instance, the mechanism is a crank-and-rocker, in which the crank is the input link and the rocker is the output link. Then, the transmission angle becomes the acute angle between the rocker and the coupler, and, indeed, its value indicates the efficacy of force transmission in the mechanism.

The single toggle jaw crusher mechanism can be modelled as a planar mechanism, as shown in Figure 1. However, in this mechanism, it is the coupler that is the output link and the transmission angle, as defined in the above cited literature, fails to be a suitable indicator of the efficacy of force transmission. Therefore, a better indicator of the efficacy of force transmission in the single toggle jaw crusher is sought in this paper.

Erdman and Sandor [1], Norton [2], and Shigley and Uicker Jr. [3] presented methods for determining the mechanical advantage of planar mechanisms that make the assumption of 100% mechanical efficiency for the mechanism and find the mechanical advantage of the mechanism to be inversely proportional to the output-to-input angular velocity ratio. The presentation by Shigley and Uicker Jr. [3] defined the mechanical advantage as the ratio of the output torque to the input torque, which led to a slightly different expression for the mechanical advantage, as compared to Erdman and Sandor [1] and Norton [2], who defined mechanical advantage as the ratio of output force to input force.

The methods presented by Erdman and Sandor [1], Norton [2], and Shigley and Uicker Jr. [3] give no indication of the actual forces that are sustained by the members of the mechanism, knowledge of which would be necessary at the design stage.

The method used in this paper includes the following:(i)A static force analysis that neglects the frictional and inertia forces is performed.(ii)All the forces and moments are assumed to be coplanar.(iii)The analysis proceeds by considering the equilibrium of the forces acting at the moving joints of the mechanism and relating them to the input torque as well as the load torque. This may be compared to the method presented by Abhary [18].The method used here is systematic and therefore clear and simple to follow and to use. As a result of the analysis, a characteristic mechanical advantage of the single toggle jaw crusher mechanism is obtained, which may be used as a criterion for selecting such mechanisms.

In the kinematical model of the single toggle jaw crusher, which is illustrated in Figure 1, the eccentric shaft is modelled as a short crank, of length , that continuously rotates about a fixed axis, at . The swing jaw is modelled as the coupler link , of length , which moves with a complex planar motion that has both rotational and translational components. The toggle link is modelled as the rocker , which oscillates about the fixed axis at . The fixed jaw is considered to be an integral part of the frame of the machine.

Oduori et al. [19] analysed the kinematics of the single toggle jaw crusher, as modelled in Figure 1, and found the following expression:Cao et al. [20] used the dimensional data for a PE single toggle jaw crusher, as shown in Table 1.

In the cycle of motion of the single toggle jaw crusher mechanism, two phases, known as the toggle phases, are of particular interest. In each of the toggle phases, the crank and the coupler link fall on a single straight line. Therefore, the toggle phases occur when and when . For the first toggle phase, equation (2) can be reduced to the following:Equation (3) is readily solved to give for the first toggle phase.

In performing the static force analysis it shall be assumed that the masses of the links, as well as friction forces, are negligible. The effects of these forces can be considered at a later stage in the design of the mechanism. In Figure 2, is the driving torque, applied at the crank axis , to drive the crank and the entire crusher mechanism. is the torque, acting about the axis of joint , due to the resistance of the feed material against being crushed. , , and are the forces in links 2, 3, and 4, respectively, and they are all assumed to be compressive. The system of forces and moments is assumed to be in equilibrium in every phase of motion of the mechanism.

Let us start by considering the crank. Static force analysis is based on the assumption that there are no accelerations in the mechanism. Referring to Figures 1, 2, and 3, the equilibrium of moments acting on the crank, about the fixed joint , leads to the following result:Next let us consider the coupler. The equilibrium of forces at joint leads to the following:From equations (5) and (6), it follows thatThe statement in equation (7) is illustrated in Figure 4.

Moreover, it should be evident from Figures 3 and 4 thatNow, in Figure 3, by considering the equilibrium of all the forces acting upon the coupler, the following is obtained:Moreover, in Figure 3, the equilibrium of moments acting on the coupler, about the joint , leads to the following result:From equations (9) and (10), it follows thatA relationship between and can now be obtained from equations (7) and (11), as follows:Equation (12) is in dimensionless form. The left-hand side of this equation can be regarded as a force transmission ratio that compares the nominal transmitted force, , to the nominal input force, . This ratio is an indicator of the theoretical force transmission potential for any given phase of motion of the mechanism.

For a given crusher mechanism, the values of and can be determined from purely kinematical considerations, by the use of (1) along with the dimensional data of the mechanism, and then the value of the right-hand side of (12) will be determined.

Using the dimensional data of the mechanism, given in Table 1, along with given values of , the corresponding values of were computed and then used in (12) to determine the corresponding force transmission ratios, for one and a half cycles of motion of the crank. The results are plotted in Figure 5.

The first spike in Figure 5 indicates the great amplification of the crushing force that occurs at the first toggle position, which corresponds to a crank angle of about . Theoretically, the crushing force amplification should be infinite at this toggle phase. Moreover, there occurs an abrupt reversal of the sign of the force transmission ratio from positive to negative, at this toggle phase. The second spike in Figure 5, which is also accompanied by a reversal in the sign of the force transmission ratio, occurs at a crank angle of about . This spike corresponds to the second toggle phase of the mechanism.

The great amplification of transmitted force, accompanied by the abrupt reversal of the sign of the force transmission ratio, at each of the toggle phases, may be compared with the phenomenon of resonance, in mechanical vibrations, which also features great amplification of the responding motion, accompanied by a reversal of the phase between the forcing and the responding functions.

As the crank rotates from to , the crusher would be on the idle stroke with the swing jaw being retracted and no work being done in crushing the feed material. This is evidenced by the negative values of the force transmission ratio, between these two angular positions of the crank, in Figure 5. Useful work is done as the crank rotates from to , in a succeeding cycle of motion of the crank. Thus, during each cycle of motion of the crank, the useful working stroke of the mechanism lasts for about of rotation of the crank, which is very slightly greater than half the cycle of motion of the crank. On the other hand, during each cycle of motion of the crank, the idle stroke lasts for of rotation of the crank, which is very slightly less than half the cycle of motion of the crank.

Thus, the mechanism has a quick return feature that is hardly noticeable since the crushing stroke lasts for 50.37% of the complete cycle of its motion, while the idle stroke lasts for 49.63% of the complete cycle of the motion of the mechanism.

In the preceding section, we have seen that the crushing stroke lasts for only about 50% of each complete cycle of motion of the single toggle jaw crusher. For the other 50% of the complete cycle of motion, the swing jaw is being retracted in preparation for the next crushing stroke.

Moreover, in Figure 5, it can be seen that the force transmission ratio varies from a very high value, at the beginning of the crushing stroke, that initially falls very rapidly and then levels off to reach a minimum value of less that unity (about 0.6), about halfway through the crushing stroke. The latter half of the crushing stroke appears to be a mirror image of the earlier half, in which the force transmission ratio first rises gradually and then spikes to a very high value at the end of the crushing stroke. Sample values of the force transmission ratio during the useful crushing stroke are given in Table 2.

The fact that the crushing stroke commences with a very high value of the force transmission ratio is advantageous when crushing brittle material, which is often the case. Since brittle materials fracture without undergoing significant deformation, actual crushing of brittle materials in a single toggle jaw crusher would occur soon after commencement of the crushing stroke, where the force transmission ratio is high.

According to Chinese jaw crusher manufacturers data [21], the PE 400 by 600 single toggle jaw crusher has 30kW motor power and an input eccentric shaft speed of 275rpm or 28.7979 radians per second. Assuming that the input speed is constant, the input torque is found to be 1.0417kNm. By using this information, along with the data in Table 1 and (12), the transmitted torque, in kilonewton-metres, can be estimated to be the following:The above calculation assumes a 100% power transmission efficiency. Equation (13) was used to calculate the values of the transmitted torque that are given in Table 3.

The above calculations reveal that the minimum value of the transmitted torque will be about 55 times as big as the input torque, with the theoretical maximum value being infinity. This is why a material that cannot be crushed will lead to breakage of the toggle link.

A force transmission ratio that would characterize the single toggle jaw crusher was calculated as the mean value of the force transmission ratio over a complete useful crushing stroke, which does not include the retraction stroke.

According to the Mean Value Theorem of the integral calculus [22], if a function is continuous on the closed interval , then the mean value of for that interval can be determined as follows:In determining the characteristic mechanical advantage, the mean value of the force transmission ratio was determined as follows:The integral in (15) was evaluated numerically by the use of the composite trapezoidal rule [23]. For , taken at one-degree intervals, the integral was evaluated as follows:For , taken as three unequal intervals, the integral was evaluated as follows:In (16) and (17), , for instance, is the value of for the case where . The total integral was then determined as follows:Thus, the characteristic mechanical advantage was determined as follows:From the preceding analysis, the force transmission characteristics for the PE 400 by 600 single toggle jaw crusher mechanism are summed up in Table 4.

The minimum force transmission ratio occurs at about the midpoint of the active crushing stroke, while the maximum force transmission ratio occurs at the end of the active crushing stroke. However, the force transmission ratio at the beginning of the active crushing stroke is also very highabout 74% of the value at the end of the crushing stroke.

Given a number of different mechanism designs, the characteristics given in Table 4 may be calculated for each candidate mechanism and used, among others, as criterion in the selection of a suitable jaw crusher mechanism for a given application.

A static force analysis of the single toggle jaw crusher mechanism was carried out. The method used is systematic, clear, and simple to follow and to use. As a result of the static force analysis, some force transmission characteristics of the single toggle jaw crusher mechanism were obtained. The analysis can also be used to determine the forces that are sustained by each of the components of the single toggle jaw crusher mechanism, provided that the values of the input torque and load torque are known.

An expression for the force transmission ratio of the single toggle jaw crusher mechanism was derived. By using the dimensional data of the PE 400 by 600 jaw crusher, the maximum value of the force transmission ratio was found to be about 3268, the minimum value of the force transmission ratio was found to be about 0.61, and the mean value of the force transmission ratio was found to be about 10.6. These metrics can be used as criteria in the selection of a suitable mechanism design to be used in a given application, out of different alternatives.

The force transmission ratio was found to be very high at the beginning of the active crushing stroke, dropped off rapidly and then levelled off at about the minimum value, remained at the low value for about two-thirds of the active crushing stroke, and then rose rapidly to a very high value at the end of the active crushing stroke. The fact that the force transmission ratio is very high at the beginning of the active stroke is advantageous in crushing brittle materials which fracture without undergoing appreciable deformation.

Copyright 2016 Moses Frank Oduori et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

crushers - an overview | sciencedirect topics

This crusher developed by Jaques (now Terex Mineral Processing Solutions) has several internal chamber configurations available depending on the abrasiveness of the ore. Examples include the Rock on Rock, Rock on Anvil and Shoe and Anvil configurations (Figure 6.26). These units typically operate with 5 to 6 steel impellers or hammers, with a ring of thin anvils. Rock is hit or accelerated to impact on the anvils, after which the broken fragments freefall into the discharge chute and onto a product conveyor belt. This impact size reduction process was modeled by Kojovic (1996) and Djordjevic et al. (2003) using rotor dimensions and speed, and rock breakage characteristics measured in the laboratory. The model was also extended to the Barmac crushers (Napier-Munn et al., 1996).

Crushers are widely used as a primary stage to produce the particulate product finer than about 50100 mm in size. They are classified as jaw, gyratory and cone crushers based on compression, cutter mill based on shear and hammer crusher based on impact.

A jaw crusher consists essentially of two crushing plates, inclined to each other forming a horizontal opening by their lower borders. Material is crushed between a fixed and a movable plate by reciprocating pressure until the crushed product becomes small enough to pass through the gap between the crushing plates. Jaw crushers find a wide application for brittle materials. For example, they are used for comminution of porous copper cake.

A gyratory crusher includes a solid cone set on a revolving shaft and placed within a hollow body, which has conical or vertical sloping sides. Material is crushed when the crushing surfaces approach each other and the crushed products fall through the discharging opening.

Hammer crushers are used either as a one-step primary crusher or as a secondary crusher for products from a primary crusher. They are widely used for crushing of hard metal scrap for different hard metal recycling processes.

Pivoted hammers are pendulous, mounted on the horizontal axes symmetrically located along the perimeter of a rotor and crushing takes place by the impact of material pieces with the high speed moving hammers and by contact with breaker plates. A cylindrical grating or screen is placed beneath the rotor. Materials are reduced to a size small enough pass through the openings of the grating or screen. The size of product can be regulated by changing the spacing of the grate bars or the opening of the screen.

The feature of the hammer crushers is the appearance of elevated pressure of air in the discharging unit of the crusher and underpressure in the zone around of the shaft close to the inside surface of the body side walls. Thus, the hammer crushers also act as high-pressure forced-draught fans. This may lead to environmental pollution and product losses in fine powder fractions.

A design for a hammer crusher (Figure 2.6) allows essentially a decrease of the elevated pressure of air in the crusher discharging unit [5]. The A-zone beneath the screen is communicated through the hollow ribs and openings in the body side walls with the B-zone around the shaft close to the inside surface of body side walls. As a result, circulation of suspended matter in the gas between A- and B-zones is established and high pressure of air in the discharging unit of crusher is reduced.

Crushers are widely used as a primary stage to produce the particulate product finer than about 50100mm. They are classified as jaw, gyratory, and cone crushers based on compression, cutter mill based on shear, and hammer crusher based on impact.

A jaw crusher consists essentially of two crushing plates, inclined to each other forming a horizontal opening by their lower borders. Material is crushed between a fixed and a movable plate by reciprocating pressure until the crushed product becomes small enough to pass through the gap between the crushing plates. Jaw crushers find a wide application for brittle materials. For example, they are used for comminution of porous copper cake. A Fritsch jaw crusher with maximal feed size 95mm, final fineness (depends on gap setting) 0.315mm, and maximal continuous throughput 250Kg/h is shown in Fig. 2.8.

A gyratory crusher includes a solid cone set on a revolving shaft and placed within a hollow body, which has conical or vertical sloping sides. Material is crushed when the crushing surfaces approach each other and the crushed products fall through the discharging opening.

Hammer crushers are used either as a one-step primary crusher or as a secondary crusher for products from a primary crusher. They are widely used for crushing hard metal scrap for different hard metal recycling processes. Pivoted hammers are pendulous, mounted on the horizontal axes symmetrically located along the perimeter of a rotor. Crushing takes place by the impact of material pieces with the high speed moving hammers and by contact with breaker plates. A cylindrical grating or screen is placed beneath the rotor. Materials are reduced to a size small enough to pass through the openings of the grating or screen. The size of the product can be regulated by changing the spacing of the grate bars or the opening of the screen.

The feature of the hammer crushers is the appearance of elevated pressure of air in the discharging unit of the crusher and underpressure in the zone around the shaft close to the inside surface of the body side walls. Thus, the hammer crushers also act as high-pressure, forced-draught fans. This may lead to environmental pollution and product losses in fine powder fractions. A design for a hammer crusher (Fig. 2.9) essentially allows a decrease of the elevated pressure of air in the crusher discharging unit [5]. The A-zone beneath the screen is communicated through the hollow ribs and openings in the body side walls with the B-zone around the shaft close to the inside surface of body side walls. As a result, the circulation of suspended matter in the gas between A and B zones is established and the high pressure of air in the discharging unit of crusher is reduced.

Secondary coal crusher: Used when the coal coming from the supplier is large enough to be handled by a single crusher. The primary crusher converts the feed size to one that is acceptable to the secondary crusher.

The main sources of RA are either from construction and ready mixed concrete sites, demolition sites or from roads. The demolition sites produce a heterogeneous material, whereas ready mixed concrete or prefabricated concrete plants produce a more homogeneous material. RAs are mainly produced in fixed crushing plant around big cities where CDWs are available. However, for roads and to reduce transportation cost, mobile crushing installations are used.

The materiel for RA manufacturing does not differ from that of producing NA in quarries. However, it should be more robust to resist wear, and it handles large blocks of up to 1m. The main difference is that RAs need the elimination of contaminants such as wood, joint sealants, plastics, and steel which should be removed with blast of air for light materials and electro-magnets for steel. The materials are first separated from other undesired materials then treated by washing and air to take out contamination. The quality and grading of aggregates depend on the choice of the crusher type.

Jaw crusher: The material is crushed between a fixed jaw and a mobile jaw. The feed is subjected to repeated pressure as it passes downwards and is progressively reduced in size until it is small enough to pass out of the crushing chamber. This crusher produces less fines but the aggregates have a more elongated form.

Hammer (impact) crusher: The feed is fragmented by kinetic energy introduced by a rotating mass (the rotor) which projects the material against a fixed surface causing it to shatter causing further particle size reduction. This crusher produces more rounded shape.

Jaw crushers are mainly used as primary crushers to produce material that can be transported by belt conveyors to the next crushing stages. The crushing process takes place between a fixed jaw and a moving jaw. The moving jaw dies are mounted on a pitman that has a reciprocating motion. The jaw dies must be replaced regularly due to wear. Figure 8.1 shows two basic types of jaw crushers: single toggle and double toggle. In the single toggle jaw crusher, an eccentric shaft is installed on the top of the crusher. Shaft rotation causes, along with the toggle plate, a compressive action of the moving jaw. A double toggle crusher has, basically, two shafts and two toggle plates. The first shaft is a pivoting shaft on the top of the crusher, while the other is an eccentric shaft that drives both toggle plates. The moving jaw has a pure reciprocating motion toward the fixed jaw. The crushing force is doubled compared to single toggle crushers and it can crush very hard ores. The jaw crusher is reliable and robust and therefore quite popular in primary crushing plants. The capacity of jaw crushers is limited, so they are typically used for small or medium projects up to approximately 1600t/h. Vibrating screens are often placed ahead of the jaw crushers to remove undersize material, or scalp the feed, and thereby increase the capacity of the primary crushing operation.

Both cone and gyratory crushers, as shown in Figure 8.2, have an oscillating shaft. The material is crushed in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly. An eccentric shaft rotated by a gear and pinion produces the oscillating movement of the main shaft. The eccentricity causes the cone head to oscillate between the open side setting (o.s.s.) and closed side setting (c.s.s.). In addition to c.s.s., eccentricity is one of the major factors that determine the capacity of gyratory and cone crushers. The fragmentation of the material results from the continuous compression that takes place between the mantle and bowl liners. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners. This is also called interparticle crushing. The gyratory crushers are equipped with a hydraulic setting adjustment system, which adjusts c.s.s. and thus affects product size distribution. Depending on cone type, the c.s.s. setting can be adjusted in two ways. The first way is by rotating the bowl against the threads so that the vertical position of the outer wear part (concave) is changed. One advantage of this adjustment type is that the liners wear more evenly. Another principle of setting adjustment is by lifting/lowering the main shaft. An advantage of this is that adjustment can be done continuously under load. To optimize operating costs and improve the product shape, as a rule of thumb, it is recommended that cones always be choke-fed, meaning that the cavity should be as full of rock material as possible. This can be easily achieved by using a stockpile or a silo to regulate the inevitable fluctuation of feed material flow. Level monitoring devices that detect the maximum and minimum levels of the material are used to start and stop the feed of material to the crusher as needed.

Primary gyratory crushers are used in the primary crushing stage. Compared to the cone type crusher, a gyratory crusher has a crushing chamber designed to accept feed material of a relatively large size in relation to the mantle diameter. The primary gyratory crusher offers high capacity thanks to its generously dimensioned circular discharge opening (which provides a much larger area than that of the jaw crusher) and the continuous operation principle (while the reciprocating motion of the jaw crusher produces a batch crushing action). The gyratory crusher has capacities starting from 1200 to above 5000t/h. To have a feed opening corresponding to that of a jaw crusher, the primary gyratory crusher must be much taller and heavier. Therefore, primary gyratories require quite a massive foundation.

The cone crusher is a modified gyratory crusher. The essential difference is that the shorter spindle of the cone crusher is not suspended, as in the gyratory, but is supported in a curved, universal bearing below the gyratory head or cone (Figure 8.2). Power is transmitted from the source to the countershaft to a V-belt or direct drive. The countershaft has a bevel pinion pressed and keyed to it and drives the gear on the eccentric assembly. The eccentric assembly has a tapered, offset bore and provides the means whereby the head and main shaft follow an eccentric path during each cycle of rotation. Cone crushers are used for intermediate and fine crushing after primary crushing. The key factor for the performance of a cone type secondary crusher is the profile of the crushing chamber or cavity. Therefore, there is normally a range of standard cavities available for each crusher, to allow selection of the appropriate cavity for the feed material in question.

Roll crushers are arbitrarily divided into light and heavy duty crushers. The diameters of the light duty crushers vary between 228 and 760mm with face lengths between 250 and 460mm. The spring pressure for light duty rolls varies between 1.1 and 5.6kg/m. The heavy duty crusher diameters range between 900 and 1000mm with face length between 300 and 610mm. In general, the spring pressures of the heavy duty rolls range between 7 and 60kg/m. The light duty rolls are designed to operate at faster speeds compared to heavy duty rolls that are designed to operate at lower speeds.

It has been stressed that the coal supplier should initially crush the materials to a maximum size such as 300 mm, but they may be something else depending on the agreement or coal tie up. To circumvent the situation, the CHP keeps a crushing provision so that coal bunkers receive the materials at a maximum size of about 2025 mm.

The unloaded coal in the hoppers is transferred to the crusher house through belt conveyors with different stopovers in between such as the penthouse, transfer points, etc., depending on the CHP layout.

Suspended magnets for the removal of tramp iron pieces and metal detectors for identifying nonferrous materials are provided at strategic points to intercept unacceptable materials before they reach the crushers. There may be arrangements for manual stone picking from the conveyors, as suitable. Crushed coal is then sent directly to the stockyard.

A coal-sampling unit is provided for uncrushed coal. Online coal analyzers are also available, but they are a costly item. Screens (vibrating grizzly or rollers) are provided at the upstream of the crushers to sort out the smaller sizes as stipulated, and larger pieces are guided to the crushers.

Appropriate types of isolation gates, for example, rod or rack and pinion gates, are provided before screens to isolate one set of crushers/screens to carry on maintenance work without affecting the operation of other streams.

Vibrating grizzly or roller screens are provided upstream of the crushers for less than 25 (typical) mm coal particles bypass the crusher and coal size more than 25 mm then fed to the crushers. The crushed coal is either fed to the coal bunkers of the boilers or discharged to the coal stockyard through conveyors and transfer points, if any.

This is used for crushing and breaking large coal in the first step of coal crushing plant applied most widely in coal crushing industry. Jaw crushers are designed for primary crushing of hard rocks without rubbing and with minimum dust. Jaw crushers may be utilized for materials such as coal, granite, basalt, river gravel, bauxite, marble, slag, hard rock, limestone, iron ore, magazine ore, etc., within a pressure resistance strength of 200 MPa. Jaw crushers are characterized for different features such as a simple structure, easy maintenance, low cost, high crushing ratio, and high resistance to friction/abrasion/compression with a longer operating lifespan.

Fixed and movable jaw plates are the two main components. A motor-driven eccentric shaft through suitable hardware makes the movable jaw plate travel in a regulated track and hit the materials in the crushing chamber comprising a fixed-jaw plate to assert compression force for crushing.

A coal hammer crusher is developed for materials having pressure-resistance strength over 100 Mpa and humidity not more than 15%. A hammer crusher is suitable for mid-hard and light erosive materials such as coal, salt, chalk, gypsum, limestone, etc.

Hammer mills are primarily steel drums that contain a vertical or horizontal cross-shaped rotor mounted with pivoting hammers that can freely swing on either end of the cross. While the material is fed into the feed hopper, the rotor placed inside the drum is spun at a high speed. Thereafter, the hammers on the ends of the rotating cross thrust the material, thereby shredding and expelling it through the screens fitted in the drum.

Ring granulators are used for crushing coal to a size acceptable to the mills for conversion to powdered coal. A ring granulator prevents both the oversizing and undersizing of coal, helping the quality of the finished product and improving the workability. Due to its strong construction, a ring granulator is capable of crushing coal, limestone, lignite, or gypsum as well as other medium-to-hard friable items. Ring granulators are rugged, dependable, and specially designed for continuous high capacity crushing of materials. Ring granulators are available with operating capacities from 40 to 1800 tons/h or even more with a feed size up to 500 mm. Adjustment of clearance between the cage and the path of the rings takes care of the product gradation as well as compensates for wear and tear of the machine parts for maintaining product size. The unique combination of impact and rolling compression makes the crushing action yield a higher output with a lower noise level and power consumption. Here, the product is almost of uniform granular size with n adjustable range of less than 2025 mm. As the crushing action involves minimum attrition, thereby minimum fines are produced with improving efficiency.

A ring granulator works on n operating principle similar to a hammer mill, but the hammers are replaced with rolling rings. The ring granulator compresses material by impact in association with shear and compression force. It comprises a screen plate/cage bar steel box with an opening in the top cover for feeding. The power-driven horizontal main shaft passes from frame side to frame side, supporting a number of circular discs fixed at regular intervals across its length within the frame. There are quite a few bars running parallel to the main shaft and around the periphery that pass through these discs near their outer edges. The bars are uniformly located about the center of the main rotating shaft. There are a series of rings in between the two consecutive disc spaces, mounted on each bar. They are free to rotate on the bars irrespective of the main shaft rotation. The entire cage assembly, located below the rotor assembly, can be set at a desired close proximity to the rings by screw jack mechanism adjustable from outside the crusher frame. The rotor assembly consisting of the shaft, discs, rings, etc., is fixed as far as the main shaft center line is concerned. This main shaft carries in roller bearings from the box sides. The movable cage frame arrangement is provided so as to set its inner radius marginally larger than that of the ring running periphery. When coal is fed from the top, the rings also rotate along with the shaft and around their own center line along the bars, which drags coal lumps and crushes them to the desired size. After the coal has been crushed by the coal crusher, a vibrating screen grades the coal by size and the coal is then transported via belt conveyor. In this process, a dewatering screen is optional to remove water from the product.

Crusher machines are used for crushing of a wide variety of materials in the mining, iron and steel, and quarry industries. In quarry industry, they are used for crushing of rocks into granites for road-building and civil works. Crusher machines are equipped with a pair of crusher jaws namely; fixed jaws and swing jaws. Both jaws are fixed in a vertical position at the front end of a hollow rectangular frame of crushing machine as shown in Fig.10.1. The swing jaw is moved against the fixed jaws through knuckle action by the rising and falling of a second lever (pitman) carried by eccentric shaft. The vertical movement is then horizontally fixed to the jaw by double toggle plates. Because the jaw is pivoted at the top, the throw is greatest at the discharge, preventing chocking.

The crushing force is produced by an eccentric shaft. Then it is transferred to the crushing zone via a toggle plate system and supported by the back wall of the housing of the machine. Spring-pulling rods keep the whole system in a condition of no positive connection. Centrifugal masses on the eccentric shaft serve as compensation for heavy loads. A flywheel is provided in the form of a pulley. Due to the favorable angle of dip between the crushing jaws, the feeding material can be reduced directly after entering the machine. The final grain size distribution is influenced by both the adjustable crusher setting and the suitability of the tooth form selected for the crushing plates.

Thus, the crusher jaws must be hard and tough enough to crush rock and meet the impact action generated by the action of swing jaws respectively. If the jaws are hard, it will be efficient in crushing rock but it will be susceptible to fracture failure. On the other hand, if the jaws are tough, the teeth will worn out very fast, but it will be able to withstand fracture failure. Thus, crusher jaws are made of highly wear-resistant austenitic manganese steel casting, which combines both high toughness and good resistance to wear.

Austenitic manganese steel was invented by Sir Robert Hadfield in 1882 and was first granted patented in Britain in 1883 with patent number 200. The first United States patents, numbers 303150 and 303151, were granted in 1884. In accordance with ASTM A128 specification, the basic chemical composition of Hadfield steel is 1%1.4% carbon and 11%14% manganese. However, the manganese to carbon ratio is optimum at 10:1 to ensure an austenitic microstructure after quenching [2]. Austenitic manganese steels possess unique resistance to impact and abrasion wears. They exhibit high levels of ductility and toughness, slow crack propagation rates, and a high rate of work-hardening resulting in superior wear resistance in comparison with other potentially competitive materials [310]. These unique properties have made Hadfield's austenitic manganese steel an engineering material of choice for use in heavy industries, such as earth moving, mining, quarrying, oil and gas drilling, and in processing of various materials for components of crushers, mills, and construction machinery (lining plates, hammers, jaws, cones).

Austenitic manganese steel has a yield strength between 50,000psi (345MPa) and 60,000psi (414MPa) [3]. Although stronger than low carbon steel, it is not as strong as medium carbon steel. It is, however, much tougher than medium carbon steel. Yielding in austenitic manganese steel signifies the onset of work-hardening and accompanying plastic deformation. The modulus of elasticity for austenitic manganese steel is 27106psi (186103MPa) and is somewhat below that of carbon steel, which is generally taken as 29106psi (200103MPa). The ultimate tensile strength of austenitic manganese steel varies but is generally taken as 140,000psi (965MPa). At this tensile strength, austenitic manganese steel displays elongation in the 35%40% range. The fatigue limit for manganese steel is about 39,000psi (269MPa). The ability of austenitic manganese to work-harden up to its ultimate tensile strength is its main feature. In this regard austenitic manganese has no equal. The range of work-hardening of austenitic manganese from yield to ultimate tensile is approximately 200%.

When subjected to impact loads Hadfield steel work-hardens considerably while exhibiting superior toughness. However, due to its low yield strength, large deformation may occur and lead to failure before the work-hardening sets in [11]. This phenomenon is detrimental when it comes to some applications, such as rock crushing [12]. Work-hardening behavior of Hadfield steel has been attributed to dynamic strain aging [13]. The hardening or strengthening mechanism has its origin in the interactions between dislocations and the high concentration of interstitial atoms also known as the CottrellBilby interaction. Thus, the wear properties of Hadfield steel are related to its microstructure, which in turn is dependent on the heat-treatment process and chemical composition of the alloy. According to Haakonsen [14], work-hardening is influenced by such parameters as alloy chemistry, temperature, and strain rate.

Carbon content affects the yield strength of AMS. Carbon levels below 1% cause yield strengths to decrease. The optimum carbon content has been found to be between 1% and 1.2%. Above 1.2% carbides precipitate and segregate to grain boundaries, resulting in compromised strength and ductility particularly in heavy sections [15]. Other alloying elements, such as chromium, will increase the yield strength, but decrease ductility. Silicon is generally added as a deoxidizer. Carbon contents above 1.4% are not generally used as the carbon segregates to the grain boundaries as carbides and is detrimental to both strength and ductility [15].

Manganese has very little effect on the yield strength of austenitic manganese steel, but does affect both the ultimate tensile strength and ductility. Maximum tensile strengths are attained with 12%13% manganese contents [16]. Although acceptable mechanical properties can be achieved up to 20% manganese content, there is no economic advantage in using manganese contents greater than 13%. Manganese acts as an austenitic stabilizer and delays isothermal transformation. For example, carbon steel containing 1% manganese begins isothermal transformation about 15s after quenching to 371C, whereas steel containing 12% manganese begins isothermal transformation about 48h after quenching to 371C [15].

Austenitic manganese steel in as-cast condition is characterized by an austenitic microstructure with precipitates of alloyed cementite and the triple phosphorus eutectic of an Fe-(Fe,Mn)3C-(Fe,Mn)3P type [17], which appears when the phosphorus content exceeds 0.04% [18]. It also contains nonmetallic inclusions, such as oxides, sulfides, and nitrides. This type of microstructure is unfavorable due to the presence of the (Fe, Mn)xCy carbides spread along the grain boundaries [19]. However, in solution-treated conditions austenitic manganese steel structure is essentially austenitic because carbon is in austenite solution [19]. The practical limit of carbon in solution is about 1.2%. Thereafter, excess carbon precipitation to the grain boundaries results, especially in heavier sections [20].

Austenitic manganese steel in the as-cast condition is too brittle for normal use. As section thickness increases, the cooling rate within the molds decreases. This decreased cooling rate results in increased embrittlement due to carbon precipitation. In as-cast castings, the tensile strength ranges from approximately 50,000psi. (345MPa) to 70,000psi (483MPa) and displays elongation values below 1%. Heat treatment is used to strengthen and increase the mechanical properties of austenitic manganese steel. The normal heat-treatment method consists of solution annealing and rapid quenching in a water bath.

Considering the mechanical properties, it is difficult to imagine that a casting made from Hadfield steel could suffer failure in service. However, cases like this do happen, especially in heavy-section elements and result in enormous losses of material and long downtimes. The reason for such failures is usually attributed to insufficient ductility, resulting from sensitivity of austenitic manganese steel to section size, heat treatment, and the rapidity and effectiveness of quenching [21]. Poor quench compounded by large section size results in an unstable, in-homogenous structure, subject to transformation to martensite under increased loading and strain rate. This article investigates the cause of incessant failure of locally produced crusher jaws from Hadfield steel.

According to the recent marketing research data conducted by the foundry an estimate of 15,000metrictons of this component is being consumed annually in the local market. This is valued at about $30million. From this market demand, the foundry plant can only supply about 5% valued at $1.5million. This is because the crusher jaws produced locally failed prematurely. Hence, this study aimed at investigating the causes of failure.

Annual wine exports in the European Union is around 21.9 billion (Eurostat) with France being the main wine exporting country followed by Italy and Spain. The wine production process (Fig. 9.1) can be divided into the following stages (Sections 9.2.1.19.2.1.4).

Grape crushers or crusher destemmers are initially used via light processing to avoid seed fracture. Sulfur dioxide is added to the mass to prevent oxidation. At this stage, grape stems are produced as one of the waste streams of the winery process. The mash is pressed in continuous, pneumatic, or vertical basket presses leading to the separation of the pomace (marc) from the must. Microbial growth is suppressed via sulfur dioxide addition.

The solids present in the must are removed before or after fermentation for white wine production. Fining is achieved by combined processes including filtration, centrifugation, flocculation, physicochemical treatment (e.g., activated carbon, gelatin, etc.,), and stabilization to prevent turbidity formation (e.g., the use of bentonite, cold stabilization techniques, etc.). Clarification leads to the separation of sediments via racking.

Wine production is carried out at temperatures lower than 20C for 610 weeks in stainless steel bioreactors or vats with or without yeast inoculation (most frequently Saccharomyces cerevisiae). At the end of fermentation, the wine is cooled (4C5C) and subsequently aged in barrels or wooden vats. The sediment that is produced during fermentation and aging is called wine lees and constitutes one of the waste streams produced by wineries. Current uses of wine lees include tartrate production and ethanol distillation. Lees could also be processed via rotary vacuum filtration for recycling of the liquid fraction and composting of the solid fraction.

Wine is cooled rapidly to facilitate the precipitation of tartrate crystals. Fining is applied for the separation of suspended particles using bentonite and gelatin. Filtration is subsequently applied to remove any insoluble compounds. The wine is finally transferred into bottles.

The main differences in the red wine production process are skin maceration duration, fermentation temperature, and unit operation sequence. Whole crushed grapes are most frequently used in red wine fermentation, which is carried out at 22C28C to facilitate the extraction of color and flavors. The remaining skins, seeds, and grape solids after fermentation are pressed to recover wine with the correct proportions of tannins and other compounds necessary for the final wine product.

carbonation of concrete

This is essentially a reversal of the chemical process that occurs when making the cement used in concrete i.e. the calcination of lime that takes place in cement kilns, which accounts for the majority of concretes embodied CO2. Carbonation is a slow and continuous process that progresses from the outer surface moving inwards.

Over the lifecycle of concrete, carbonation will result in the reabsorption of around a third of the CO2 emitted when making cement, significantly reducing the whole-life CO2 footprint of both the cement and the concrete for which it is used. For this reason, it is important to ensure the environmental benefit of carbonation is accounted for when carrying out a life cycle assessment of concrete and buildings constructed from it.

If the carbonation front reaches steel reinforcement it can cause corrosion, so the mix design of structural concrete purposefully limits the rate of carbonation, preventing this problem from occurring during the life of buildings and infrastructure. There is, however, a greater degree of carbonation during the end-of-life stage, when concrete is crushed for reuse as an aggregate.

The crushing process substantially increases the materials surface area, allowing CO2 to be more readily absorbed. Although the deconstruction and demolition process at end-of-life can be comparatively brief, the resulting carbonation during this phase is significant.

In addition to direct absorption of atmospheric CO2, the newly crushed concrete aggregate also undergoes carbonation as a consequence of leaching from exposure to rain; a process that has been shown to significantly increase the rate of carbonation. Further CO2 uptake occurs during the materials secondary-life stage, when the recycled aggregate is used in a range of applications.

In lower strength concrete where no steel reinforcement is used, such as blocks, carbonation is more rapid during its service life, as CO2 can permeate the material more easily. In addition to the absorption of CO2, the carbonation process is also likely to increase the strength of these materials, and with no steel reinforcement present, their serviceable lifespan has the potential to be measured in hundreds rather than tens of years. The Pantheon in Rome, constructed around 1900 years ago provides demonstrable evidence of this.

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failure mechanism of compressed short brick masonry columns confined with frp strips - sciencedirect

Experimental research of FRP strengthened brick masonry columns was carried out.Glass (GFRP) and carbon (CFRP) fabrics were used for strengthening.The columns were reinforced by wrapping the FRP strips in 4 height levels.Research has proven effectiveness of masonry columns strengthening by FRP wrapping.Failure mechanism has decisive influence on determination of load-bearing capacity.

The article addresses the issues of strengthening and stabilisation of compressed masonry structures by inorganic FRP fabrics. The confinement of a masonry column with fabrics of carbon fibres with a high modulus of elasticity and high tensile strength relieves the transverse tensile stresses in the masonry and increases the ultimate deformation and the ultimate load. The experimental research of brick masonry columns under concentric load performed to-date has pointed out the necessity of adopting a different approach to assessing the load-bearing capacity or residual load-bearing capacity, which takes into account the different failure modes of reinforced and unreinforced brick masonry.