CRUSHING DEVICE COMPRISING AN OVERLOAD SAFETY DEVICE

Abstract

A crushing device such as a cone or gyratory crusher, the crushing device comprising: a shaft defining a first direction parallel to its length, the shaft comprising an upper shaft end; a crusher head; and an overload safety device coupling the crusher head to the upper shaft end, the overload safety device comprising a deflection device configured to deflect the crusher head away from the upper shaft end in the first direction, wherein: the overload safety device is configured to permit displacement of the crusher head along the first direction with respect to the shaft in response to a force acting on the crusher head in the first direction.

Description

The present invention relates to an overload safety device for use in a rotary crusher or cone crusher. BACKGROUND OF THE INVENTION Cone crushers and gyratory crushers are two types of rock crushing systems that generally break down rock, stone, or other material in a crushing cavity between a stationary and a moving element. A cone or gyratory crusher consists of a head assembly that includes a crusher head rotating around a vertical axis within a stationary bowl attached to the main frame of the rock crusher. The crusher head is assembled around an eccentric that rotates around a fixed shaft to impart the rotary motion to the crusher head, which crushes the rock, stone, or other material in the crushing cavity between the crusher head and the bowl.The eccentric can be driven by a variety of power actuators, such as a coupled gear, driven by a pinion and secondary shaft assembly, and various sources of mechanical power, such as electric motors or combustion engines. The rotating motion of the crusher head relative to the stationary bowl crushes rock, stone, or other material as it moves through the crushing chamber. The crushed material exits the cone crusher through the bottom of the crushing chamber. Gyratory crushers and cone crushers are typically equipped with crossarms. These crossarms protect the crusher head from damage caused by large impacts from materials dropped onto it. For example, WO 2014 / 135306 A1 discloses crossarm protection for a gyratory crusher. However, such crossarms reduce the crusher's feed capacity. Therefore, there is a need to reduce the number of cross arms or completely eliminate the need for cross arms. There is also a need to better manage the overload of material to be shredded so that non-shredderable material, such as unwanted material, can pass through the device. Overload can refer to an overload of shreddable material and / or a load of non-shredderable material. BRIEF DESCRIPTION OF THE INVENTION According to the present invention, a crushing device, such as a cone or gyratory crusher, is provided. The crushing device comprises a shaft, a crusher head, and an overload safety device. The shaft defines a first direction parallel to its length. The shaft includes an upper shaft end. The overload safety device couples the crusher head to the upper shaft end. The overload safety device includes a deflection device configured to deflect the crusher head away from the upper shaft end in the first direction. The overload safety device is configured to permit displacement of the crusher head along the first direction relative to the shaft in response to a force acting on the crusher head in the first direction. In this disclosure, the force acting on the crusher head in the first direction can result from any force acting on the crusher head with a force component acting in the first direction. With this type of configuration, it is possible to protect the crusher head from damage caused by large impacts from materials dropped onto it. This configuration is particularly advantageous in a crusher without a crosshead or a crusher with a reduced number of crosshead arms, as it allows for increased intake capacity. Furthermore, with the above configuration it is possible to better manage the overload of material to be crushed so that non-crushing material such as unwanted material can pass through the device. BRIEF DESCRIPTION OF THE FIGURES The aforementioned objects, features, and advantages, as well as additional ones, of the present invention will be better understood through the following detailed, illustrative, and non-limiting description of preferred embodiments of the present invention with reference to the accompanying figures, in which the same reference numbers will be used for similar elements, where: Fig. 1 schematically shows a rotary crusher according to an embodiment of the present invention. Fig. 2 schematically shows an air chamber accumulator type overload safety device according to the present invention. Figure 3 schematically shows a piston accumulator overload safety device according to the present invention, Fig. 4 schematically shows a diaphragm accumulator overload safety device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION Figure 1 schematically illustrates a rotary crusher 1 in section. The rotary crusher 1 has a vertical shaft 2 and a frame 4. The shaft 2 has a longitudinal axis that defines a first direction that coincides with a central axis A of the crusher. The upper and lower eccentric rings 10 and 11 of an eccentric assembly are rotatably supported around the shaft 2 by means of two rotating shaft bearings, such as rotary sliding bearings. However, the crusher eccentric may also include a single eccentric element that is continuously eccentric along its axial length, as is the case with many crushers known in the art. A crusher head 12 is radially supported by, and rotates about the eccentric rings 10, 11 via another pair of rotating bearings, as well as another pair of rotating sliding bearings. Together, the shaft bearings and the head bearings form an eccentric bearing arrangement to guide the crusher head 12 along a rotating path. A drive shaft 14 is connected to a drive motor and is equipped with a pinion 15. The drive shaft 14 is arranged to rotate the lower eccentric ring 11 by means of the pinion bQQC ίη / ZZΖΠZ / E / YΙΛΙ which meshes with a gear ring 16 mounted on the lower eccentric ring 11. When the drive shaft 14 rotates the lower eccentric ring 11, during the operation of the crusher 1, the crusher head 12 mounted on it will perform a rotary motion. An inner crushing casing or sleeve 13 is mounted on the crusher head 12. An outer crushing casing or bowl 5 is mounted on the frame 4. A crushing cavity 17 is formed between the two crushing casings 13, 5. When the crusher 1 is operated, material to be crushed is introduced into the crushing cavity 17 and is crushed between the sleeve and the bowl 5 as a result of the rotary motion of the crusher head 12, motion during which the sleeve 13 approaches the bowl along a generatrix of rotation and moves away from it along a diametrically opposite generatrix. The crusher head 12 is supported on a free upper end bearing 19 provided at a free upper end 2a of the shaft 2 by means of an overload safety device 30. The overload safety device 30 comprises an upper element 33 fixed to an extended portion 12a (see Fig. 2) of the crusher head 12 such that movement of the crusher head 12 in the first direction results in a corresponding movement of the upper element 33 of the overload safety device 30 in the first direction. The overload safety device 30 comprises a seal 31 rotatably housed in the free upper end bearing 19 and a deflection device 32 disposed between the seal 31 and the upper element 33.The deflection device 32 acts to deflect the joint 31 and the upper element 33 away from each other in such a way that the crusher head 12 is deflected away from the shaft 2. The head bearings allow the crusher head 12 to move in the first direction with respect to the eccentric, i.e., in the present embodiment, the eccentric rings 10 and 11. The overload safety device 30 allows the crusher head 12 to move along the first direction with respect to the shaft 2 in response to a force acting on the crusher head 12 in the first direction. The deflection device 32 is configured to return the crusher head 12 to an equilibrium position when a constant force is applied to the crusher head 12. Impacts on the crusher head 12 from materials dropped onto the crusher head 12 result in the crusher head 12 moving along the first direction towards shaft 2. With this type of configuration, it is possible to protect the crusher head 12 from damage caused by large impacts from materials dropped onto the crusher head 12. If the load acting on the crusher head 12 is released, the deflection device 32 of the overload safety device 30 returns the crusher head 12 to an equilibrium position. With this configuration, the crusher head 12 recovers from impacts so that it can move back toward the shaft 2 in response to any further impact. If non-crushable material is fed into the crushing pit 17, the overload safety device 30 allows the crusher head 12 to move along the first direction towards the shaft 2, increasing the distance between the two crushing housings 13.5. This allows the non-crushable material to pass through the crushing pit 17. With this configuration, the crusher 1 can better manage the overload of material to be crushed, allowing non-crushable material, such as unwanted material, to pass through the device if fed into the crushing pit 17. Once the non-crushable material passes through the crushing pit 17, the deflection device 32 of the overload safety device 30 returns the crusher head 12 to an equilibrium position. The overload safety device 30 depicted in Fig. 1 is an air chamber accumulator overload safety device, which is further described herein. However, the overload safety device 30 may comprise any form of deflection device capable of diverting the crusher head 12 away from the upper free end 2a of the shaft 2. Non-limiting examples of deflection devices suitable for use in an overload safety device according to the present invention include air chamber accumulators; piston accumulators; diaphragm accumulators; and springs. Optionally, the overload safety device can be configured to provide a “soft return” of the crusher head from a displaced position. In other words, the overload safety device can be configured to dampen the return of the crusher head 12 from the displaced position to an equilibrium position, so that the return is slower than the rapid and sudden displacement to which the crusher head 12 is subjected after an impact. Hydraulic damping, friction resistance damping, and magnetic damping are non-limiting examples of the types of damping suitable for use in an overload safety device according to the present invention. Figure 2 schematically illustrates an air chamber accumulator overload safety device 40 according to the present invention. The air chamber accumulator overload safety device 40 comprises a seal 41 rotatably housed in the free upper end bearing 19. The air chamber accumulator overload safety device 40 comprises an upper element 43 and an air chamber 42 disposed between the seal 41 and the upper element 43. The upper element 43 of the overload safety device 40 is fixed to the extended portion 12a of the crusher head 12 such that movement of the crusher head 12 in the first direction results in a corresponding movement of the upper element 43 in the first direction. The extended portion 12a of the crusher head 12 can slide relative to the seal 41. The extended portion 12a, the seal 41, and the upper element 43 work together to define a cavity C containing a liquid 44 that surrounds the air chamber 42. The seal 41 and the upper element 43 can move relative to each other such that the volume of the cavity C can be increased or decreased. A reduction in the volume of the cavity C results in the liquid 44 compressing the air chamber 42.The compression of the air chamber 42 results in a compression of a gas 45 contained in the air chamber 42, which thereby acts to deflect the upper element 43 away from the joint 41. The displacement of the crusher head 12 towards the shaft 2 results in the displacement of the upper element 43 towards the joint 41. This results in a reduction of the volume of cavity C. The reduction in the volume of cavity C exerts pressure on at least the liquid 44, which acts to compress the air chamber 42 and the gas 45. The air chamber 42 containing the gas 45 acts as a deflection device to deflect the crusher head 12 away from the shaft 2. Figure 3 schematically illustrates an overload safety device 50 for a piston accumulator 50 according to the present invention. The overload safety device 50 comprises a seal 51 rotatably mounted in the free upper end bearing 19. The overload safety device 50 for a piston accumulator 50 comprises a lower element 58 fixed to the seal 51. In the overload safety device 50 for a piston accumulator 50, the upper element is a chamber element 53. A piston P is slidably arranged within the chamber element 53. A gas 59 is contained within a cavity C defined between the chamber element 53 and the piston P.The piston P can slide relative to the chamber element 53 to compress the gas 59. A valve assembly 55 is attached to the chamber element 53. The chamber element 53, the piston P, and the valve assembly 55 work together to define a first chamber C1 between them. The extended portion 12a, the valve assembly 55, and the lower element 58 work together to define a second chamber C2 between them. The first chamber C1 and the second chamber C2 are configured to contain a liquid 54. The valve assembly 55 allows fluid 54 to flow from the first chamber C1 to the second chamber C2 and vice versa. The valve assembly 55 comprises at least one low-resistance orifice 55c and at least one high-resistance orifice 55d. The low-resistance orifice 55c has lower fluid resistance than the high-resistance orifice 55d for fluid 54 flowing through the orifices. Orifices 55c and 55d allow fluid 54 to flow from the first chamber C1 to the second chamber C2 and vice versa. The valve assembly 55 further comprises a valve including a spring 55a and a sealing element 55b. The sealing element 55b is disposed within the first chamber C1 and is deflected by the spring 55a toward the low-resistance orifice 55c to seal the low-resistance orifice 55c.Such a configuration allows fluid 54 to flow from the second chamber C2 to the first chamber C1 with low fluid resistance, but provides high fluid resistance to flow from the first chamber C1 to the second chamber C2. A force on the crusher head 12 in the first direction toward shaft 2 results in the movement of chamber element 53 toward the lower element 58. The movement of chamber element 53 toward the lower element 58 results in the liquid 54 contained in the second chamber C2 flowing with low resistance into the first chamber C1 through the valve assembly 55. In this flow direction, the valve in the valve assembly is open so that liquid 54 can flow through the low-resistance orifice 55c. An increased pressure in the first chamber C1 due to the flow of liquid 54 results in the displacement of piston P such that the gas 59 contained in cavity O is compressed due to the reduction in the volume of cavity O. This compression of the gas 59 contained in cavity C results in a deflection force that acts to deflect the crusher head 12 away from shaft 2. Once the force on the crusher head 12 is removed, the pressure in cavity C causes piston P to shift, increasing the volume of cavity C and decreasing the volume of the first chamber 01. This decrease in the volume of the first chamber C1 results in fluid 54 bQQC Ln / Zznz / E / YIAI flowing with high resistance from the first chamber 01 to the second chamber 02 through the valve assembly 55. In this flow direction, the valve in the valve assembly is closed, preventing fluid 54 from flowing through the low-resistance orifice 55c, and allowing it to flow only through the high-resistance orifice 55d. This causes the overload safety device 50 to slowly return to its equilibrium position. In this way, the overload safety device 50 ensures a smooth return of the crusher head 12 from its displaced position. Figure 4 schematically illustrates a diaphragm accumulator overload safety device 60 according to the present invention. The diaphragm accumulator overload safety device 60 is substantially similar to the piston accumulator overload safety device 50, but with the piston P replaced by a diaphragm D. The perimeter of the diaphragm D is fixed to the chamber element 53 such that the pressure in the first chamber C1 deforms the diaphragm D away from the valve assembly. Figure 4 shows the diaphragm D in a deformed configuration. The invention is not limited to the above modalities. For example, the preceding modalities describe a specific configuration in which the overload safety device is connected to a shredder. However, the overload safety device simply needs to couple the shredder head 12 to the upper shaft end 2a in such a way as to allow the shredder head 12 to move along the first direction. Furthermore, the crushers described above and illustrated in the figures have the crusher head 12 mounted on bearings on the eccentric outer surface of the eccentric 10,11, while the shaft 2 extends along the main shaft A of the crusher, so that the eccentric rotates around the shaft 2 and applies a rotary motion to the crusher head 12. However, the present invention can also be applied to crushers having the crusher head mounted on bearings on the shaft which in turn is mounted on bearings on an eccentric inner surface of the eccentric, so that the rotary motion is applied to the shaft. Although the embodiments described above refer to a stationary crusher, the solution according to the present invention can also be applied to mobile crushing plants. The overload safety system provided by the present invention will reduce the impact peaks induced by falling rocks and the crushing operation on the support frame. This can be particularly advantageous for mobile equipment, which has a less rigid support structure than a stationary crusher.

Claims

1. A crushing device, preferably a cone or gyratory crusher, the crushing device characterized in that it comprises: a shaft (2) defining a first direction parallel to its length, the shaft (2) comprising an upper shaft end (2a); a crusher head (12);and an overload safety device (30) coupling the crusher head (12) to the upper shaft end (2a), the overload safety device (30) comprising a deflection device (32) configured to deflect the crusher head (12) away from the upper shaft end (2a) in the first direction, wherein: the overload safety device (30) is configured to permit displacement of the crusher head (12) along the first direction relative to the shaft (2) in response to a force acting on the crusher head (12) in the first direction, wherein the deflection device is an accumulator comprising: a gas chamber (C); a first liquid chamber (O1); a second liquid chamber (O2); and a movable element (P, D) disposed between the gas chamber (C) and the first liquid chamber (C1);wherein the gas chamber (C) is configured to contain a pressurized gas (59) such that it can be compressed by a movement of the moving element (P, D); wherein the first liquid chamber (C1) is configured to contain a liquid (54) such that it can impart movement to the moving element (P, D); wherein the second liquid chamber (O2) is configured to contain the liquid (54) such that it can be pressurized due to the force acting on the crusher head (12) in the first direction.

2. The crushing device according to claim 1, further characterized in that it additionally comprises a bearing (19) provided at the upper shaft end (2a), and wherein the overload safety device (30) additionally comprises a seal (31) housed in the bearing (19).

3. The crushing device according to claim 2, further characterized in that the bearing (19) is a spherical bearing, and the seal (31) is a spherical seal.

4. The crushing device according to claim 2 or 3, further characterized in that the overload safety device (30) additionally comprises an upper element (33), and wherein the deflection device (32) is arranged between the upper element (33) and the seal (31).

5. The crushing device according to claim 1, further characterized in that the accumulator is a piston accumulator, wherein the moving element is a piston (P).

6. The crushing device according to claim 1, further characterized in that the accumulator is a diaphragm accumulator, wherein the moving element is a diaphragm (D).

7. The crushing device according to any of claims 1 to 6, bQQC ίη / ZZΖΠZ / E / YΙΛΙ characterized further in that it additionally comprises a valve assembly (55) disposed between the first liquid chamber (C1) and the second liquid chamber (C2), wherein the valve assembly (55) is configured to allow the liquid (54) to flow from the second chamber (C2) to the first chamber (C1) with less resistance than a flow from the first chamber (C1) to the second chamber (C2).

8. The crushing device according to claim 7, further characterized in that the valve assembly (55) comprises: a low-resistance check valve configured to allow liquid (54) to flow through from the second chamber (C2) to the first chamber (O1) but not to allow liquid (54) to flow through from the first chamber (O1) to the second chamber (O2); and a high-resistance bypass orifice (55d) configured to allow liquid (54) to flow through from the first chamber (O1) to the second chamber (O2).

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