WO2021013329A1

WO2021013329A1 - Retaining assembly for inner crushing shell of gyratory crusher

Info

Publication number: WO2021013329A1
Application number: PCT/EP2019/069634
Authority: WO
Inventors: Johan Gunnarsson
Original assignee: Sandvik Srp Ab
Priority date: 2019-07-22
Filing date: 2019-07-22
Publication date: 2021-01-28

Abstract

A retaining assembly (102) to secure an inner crushing shell (101) at a shaft-mounted head center (201) of a gyratory crusher. The retainer assembly (102) comprises a modular construction comprising a retaining nut (204) and a cover plate (205) which are affixed together owing to the presence of corresponding splines (209, 210) on their physically contacting surfaces. The splines mechanically engage to result in a rotational lock. The assembly (102) further comprises of a torch ring (206) positioned between the cover plate (205) and the inner crushing shell (101). After the retaining assembly is tightened, the torch ring (206), upon application of heat, burns thereby welding the shell (101) to the cover plate (205).

Description

Retaining assembly for inner crushing shell of gyratory crusher

Technical field

The present disclosure relates to gyratory crushers. More specifically, the present disclosure relates to a retaining assembly for securing an inner crushing shell on to a head center mounted on a main shaft of a cone crusher or a gyratory crusher.

Background art

Gyratory crushers are used for crushing ore, mineral and rock material to smaller sizes. Typically, the crusher comprises a head center mounted upon an elongate main shaft. A first crushing shell or the inner crushing shell (typically referred to as a mantle) is mounted on the head center and a second crushing shell or the outer crushing shell (typically referred to as the concave) is mounted on a frame such that the first and second crushing shells define together a crushing chamber through which the material to be crushed is passed. A driving device positioned at a lower region of the main shaft is configured to rotate an eccentric assembly positioned about the shaft to cause the head center to perform a gyratory pendulum movement and crush the material introduced in the crushing chamber.

In the course of the crushing operation, the crushing shells are worn down, which means that they need to be replaced at regular intervals. A variety of different assemblies have been proposed for mounting the inner crushing shell at the main shaft in an attempt to provide a reliable lock as well as convenient mounting and dismounting of the inner crushing shell. Examples include assemblies described in US7216823, EP1581344, WO2013/009531. Replacing the inner crushing shell usually involves the use of a cutting blowpipe and a sledgehammer. Use of this technique is potentially hazardous for the operator since the operator is required to use a heavy hammer or bar to tighten the head nut. In some instances, the assemblies cannot handle adequately the significant torque induced during crushing operations. One such example has been described in EP2535110, wherein the retaining assembly comprises an eccentric head nut positioned radially intermediate the main shaft and engaging with an eccentric region of the mantle so as to provide a self-tightening assembly. The significant shear forces generated during the crushing operation within the retaining assembly can cause possible reduction in the operational lifetime of the components of the assembly.

Some of these problems have been addressed in EP2929940. The retaining assembly described in this document comprises a head nut, a cover ring and at least one abutment member for rotationally coupling the cover ring with head nut into a lock. The abutment member or the pin which used for locking the head nut and the cover ring is likely to break off due to the forces acting on it during the crushing operations. This would result in the loosening of the components of the retaining assembly. Another drawback of the retaining assembly described in this document is that it relies on the friction between the cover plate and the inner crushing shell to tighten or hold the inner crushing shell and the cover plate together. This frictional force is not enough for the tightening of the inner crushing shell and can further lead to the failure of the retaining assembly during crushing operations.

Accordingly, there is a need for a retaining assembly for securing the mantle on to the head center of the shaft which addresses the above-mentioned drawbacks.

Summary

It is an objective of the present disclosure to solve or at least mitigate parts of the above- mentioned problems.

It is an objective of the present disclosure to provide a retaining assembly for securing the inner crushing shell on to the head center mounted at the main shaft, that allows convenient and easy mounting and dismounting of the shell.

It is another objective of the present disclosure to provide a retaining assembly for securing the inner crushing shell on to the head center mounted at the main shaft, that does not compromise the safety of the operator for tightening of the inner crushing shell and is easy to maintain. It is a further specific objective of the present disclosure to minimize the risk of failure of the retaining assembly and to extend as far as possible the service lifetime of components of the assembly.

The objectives are achieved by providing a retaining assembly which secures the inner crushing shell to the head center mounted on the main shaft. This retaining assembly comprises of components which are rotationally locked thereby rendering the assembly stable and resistant to early failure. The assembly also provides a strong and durable hold to the inner crushing shell which is pressed on to the seating surface of the head center mounted on the main shaft.

According to a first aspect of the present disclosure, there is provided a retaining assembly for securing an inner crushing shell on a shaft mounted head center of a gyratory crusher, the assembly comprising a retaining nut having a radially outer surface and a threaded radially inner surface for engaging with an annular inner head nut which is positioned radially around an axial upper region of the shaft; a cover plate with a radially inner surface and a radially outer surface, the inner surface being in physical contact with the radially outer surface of the retaining nut and; a plurality of fasteners or attachment means for connecting the cover plate to the retaining nut characterized in that the radially outer surface of the retaining nut is provided with a plurality of projections.

Preferably, the projections of the retaining nut are distributed circumferentially along the outer surface of the nut. These projections are configured to mechanically engage the cover plate in a rotational lock with the nut in such a way that upon locking, the retaining assembly is enabled to press the inner crushing shell between the cover plate and the seating surface of the head center for mounting the shell on the head of the gyratory crusher.

Advantageously, the mechanical engagement of the nut and the cover plate is sufficiently strong to provide stability to the assembly during the crushing operation. The retaining assembly is hence rendered capable of holding together the inner crushing shell when the crusher is in operation. Another advantage is that the assembly allows easy and convenient mounting and dismounting of the inner crushing shell, when the shell gets worn out and needs to be replaced.

Preferably, the retaining assembly further comprises a metallic ring which is also known as a torch ring or a burn ring, the ring being capable of welding together the inner crushing shell and the cover plate on application of heat. This ring is preferably disposed between the cover plate and the top edge of the inner crushing shell. The metallic ring is preferably made of mild steel, and on application of heat, the ring welds together the cover plate and the inner crushing shell. The advantage of having a torch ring is that it provides a strong hold of the inner crushing shell and provides a safe alternative for the operator since the operator no longer needs to use a sledge hammer for tightening the shell on the retaining assembly. The welding facilitates self tightening of the inner crushing shell, removing the need for sledgehammering which can be hazardous for the operator. Another advantage of the torch ring is that dismounting of the shell is easy and convenient since the ring would have burned away, and by releasing the forces on the bolts, it is easy to remove the shell.

Preferably, the torch ring has a rounded profile. Optionally, it can have a square or any other profile.

Optionally, the annular inner head nut which is positioned radially around the axial upper region of the main shaft of the crusher, is provided with a threaded radially outer surface for mechanically engaging with the threaded radially inner surface of the retaining nut. The advantage is that the corresponding threaded surfaces of the inner head nut and the retaining nut form a mechanical attachment which further aides the retaining assembly to be stable.

Preferably, the cover plate is provided with a plurality of projections on its radially inner surface such that these projections are complementary to the projections on the outer surface of the retaining nut. The advantage of these complementary projections on the cover plate is that upon mechanical engagement with the projections on the retaining nut, there is established a stable rotational lock which holds the nut and the plate together. This eliminates the need to have additional components in the retaining assembly for the purpose of locking the nut and the plate together, thereby reducing the overall cost and weight of the retaining assembly.

Preferably, the projections on the cover plate and the retaining nut are in the form of vertical splines arranged circumferentially on both the surfaces and configured to engage with the complementary splines to provide a strong and stable mechanical hold. Optionally, the projections may be in any other irregular form or any other shape as long as the projections on the corresponding engaging surface are adaptable to mate with these projections.

Optionally, instead of having projections, the retaining nut can also be provided with an eccentric part or eccentric surface for enabling mechanical engagement with the cover plate. Similarly, instead of projections, the cover plate can optionally be provided with an eccentric part or eccentric surface corresponding to the eccentricity of the retaining nut. The advantage offered by this feature is the ease of fabrication of the components, and also strong and durable mechanical hold within the retaining assembly.

Further, it is preferred that the retaining nut is also provided with a flange projecting radially outwards from its lower perimeter region, for attaching the fasteners that provide the axial force for pressing the inner crushing shell down to the seating surface of the head center. Preferably, the fasteners are in the form of screws which are spring loaded. Optionally, the fasteners can be in the form of bolts, standard screws, washers, buttons, clamps, pins, pegs or nuts.

Preferably, both the cover plate and the retaining nut are provided with a plurality of holes or grooves for receiving the fasteners which affix the cover plate and the retaining nut, thereby creating axial force on the inner crushing shell when tightened. Advantageously, the fasteners in the holes are well- suited for taking up tensile loads along the axial direction of the body of the fasteners.

According to a second aspect of the present disclosure, there is provided a method for securing the inner crushing shell on the shaft mounted head of the gyratory crusher. The steps of the method include, providing a retaining assembly comprising of a retaining nut and a cover plate; threading the retaining nut on to the inner head nut; positioning the inner crushing shell on the head center of the gyratory crusher; mounting the cover plate on top of the inner crushing shell while having the torch ring disposed between the cover plate and the inner crushing shell; fastening the cover plate to the retaining nut using fasteners for tightening down the inner crushing shell in such a way that the cover plate is rotationally locked to the retaining nut by means of complementary projections on the physically contacting surfaces of the cover plate and the retaining nut. This method further involves the welding of the cover plate with the inner crushing shell by means of the torch ring which burns on application of heat joining the cover plate and inner crushing shell together.

Advantageously, this method results in a strong retention of the inner crushing shell as it gets tightened on to the head center by means of the retaining assembly. This method also removes the need for sledgehammering for tightening of the inner crushing shell, which can be hazardous for the operator. There is also no requirement of additional components like abutment members for this method, as the complementary splines (projections) on the retaining nut and the cover plate mechanically engage to form a stable rotational lock. Such a method provides for a fast, simple and convenient retention of the inner crushing shell on to the head center of the crusher. According to a third aspect of the present disclosure, there is provided a gyratory crusher comprising an elongate main shaft for gyroscopic precession within the crusher; a head mounted at the main shaft; an inner crushing shell mounted at the head; and a retaining assembly comprising a retaining nut and a cover plate configured to mount the inner crushing shell on to the head.

Brief description of drawings

A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

Figure 1 is an external perspective view of a main shaft mounting an inner crushing shell suitable for gyroscopic precession within a gyratory crusher, the shell secured at the main shaft via a retainer assembly according to a specific implementation of the present disclosure;

Figure 2 is a perspective cross-sectional view of the shaft, inner crushing shell, head and the retainer assembly of Figure 1;

Figure 3 is a vertical cross-sectional view of the shaft, shell, head and the retainer assembly showing the manner in which the tightening of the shell is achieved;

Figure 4 is an exploded perspective view of the retaining assembly along with the shell, head and the main shaft;

Figure 5 is an underside view of the retaining assembly independent of the main shaft and the head and;

Figure 6 is a perspective exploded view of the retainer assembly showing the eccentric versions of the retaining nut and the cover plate configured to engage in a form-fitting engagement according to one of the embodiments of the present disclosure. Detailed description of preferred embodiment of the invention

Referring to Figure 1, an inner crushing shell (mantle) 101 of a gyratory crusher is mounted at the main shaft 100 via a head center 201 (not shown) which is generally conical in shape. The head center 201 is mounted to surround a lengthwise region of the main shaft 100. The shaft 100 is rotatably driven by suitable drives and gears (not shown) to enable precession within the crusher to displace shell 101 radially relative to the outer crushing shell (not shown), which results in crushing of the material when the crusher is in operation. The shell 101 is retained at the head center 201 via a retainer assembly 102 which is generally concentric relative to the shell 101 and the shaft 100 so as to be centered on a longitudinal axis 103 extending through the shaft 100.

Referring to Figure 2, the components of the retaining assembly 102 can be seen in the perspective cross-sectional view of the shell 101 mounted on the shaft 100. The retaining assembly 102 comprises a modular construction formed from a retaining nut 204 and a cover plate 205. The plate 205 is affixed to the nut 204 by mechanical engagement of the complementary splines (209, 210) on the contacting surfaces of the plate 205 and the nut 204. The head center 201 is mounted on the shaft 100 as shown in the figure. The shell 101 is positioned to be retained on the seating surface 202 of the head center 201 by means of the retaining assembly 102.

The retaining assembly further comprises of a torch ring 206 which is disposed between the cover plate 205 and the shell 101. The torch ring 206 is intended to weld together the cover plate 205 and the shell 101 on application of heat so that the shell 101 gets tightened on to the seating surface 202 of the head center 201. The retaining assembly 102 further strengthens the hold by the use of fasteners 207, 208 which may be in the form of bolts or spring-loaded screws. The fasteners 207, 208 pass through the holes of the cover plate 205 and extend axially downwards to pass through the holes present in the flange 401 of the nut 204.

Figure 3 illustrates the retaining assembly 102 when it is tightened and holding the inner crushing shell 101. Referring to both Figures 3 and 4, an inner head nut 203 which is generally annular and comprises a radially inner surface 212 and a radially outer surface 211, is positioned radially around the axial upper region of the main shaft 100. The inner head nut 203 is provided with a threaded outer surface 211 which enables the nut 203 to cooperate with a part of the threaded inner surface 214 of the retaining nut 204. The retaining nut 204 is provided with a flange 401 projecting radially from the lower end of the nut 204 in such a way that the flange 401 receives the fasteners 207, 208 in the holes 402 which are distributed uniformly across the circumference of the flange 401.

The inner crushing shell 101 is positioned on the head center 201. The cover plate 205 which is annular, is positioned on axially upper region of the retaining nut 204. The plate 205 is provided with splines 210 on its radially inner surface 215. Complementary splines 209 are provided on the radially outer surface 213 of the retaining nut 204. The splines 209 and 210 enable form-fitting mechanical engagement between the retaining nut 204 and the cover plate 205, enabling a rotational lock between them. The retaining assembly 102 is further tightened using fasteners which may be in the form of bolts and screws (207, 208) to hold the cover plate

205 in position along the axially upper region of the retaining nut 204. The bolts 207 extend axially downwards through the apertures 403 of the cover plate 205 and the aperture 402 of the retaining nut 204 to couple the cover plate 205 and the retaining nut 204. These bolts 207 are uniformly distributed in a circumferential manner passing through the cover plate 205 and the nut 204. The apertures 402 and 403 on both the components of the assembly 102 are suitably dimensioned to receive the bolts 207 and the screws 208. The torch ring 206 is disposed between the top edge 220 of the inner crushing shell 101 and the lower surface 217 of the cover plate 205. After the tightening of the retaining assembly 102 is achieved, the inner crushing shell 101 is welded to the cover plate 205 by application of heat which causes the torch ring

206 to bum.

Referring to Figure 5, the retaining assembly 102 is depicted according to a specific implementation of the present disclosure. The cover plate 205 and the retaining nut 204 are rotationally locked in a form-fitting mechanical engagement with the use of splines 209 on the outer surface 213 of the retaining nut 204 and the complementary splines 210 on the inner surface 215 of the cover plate 205.

According to yet another implementation of the present disclosure, the cover plate 205 and the retaining nut 204 are in the form of corresponding eccentric components configured to mate via their physically contacting surfaces as illustrated in Figure 6. The circular cross-section of the radially inner surface 215 of the cover plate 205 is eccentric with respect to the longitudinal axis 103 which is corresponding to the eccentricity of the circular cross-section of the radially outer surface 213 of the retaining nut 204. The eccentricity causes the wall thickness of the nut 204 and the cover plate 205 to be non-uniform, in such a way that the two components are configured to engage owing to their corresponding eccentricities. Specifically, the wall thickness on the right side of the cover plate 205 shown in the figure is greater than the wall thickness on the left side of the plate.

The inner crushing shell 101 may be attached to the head center 201 using the method described as follows. The inner head nut 203 is threaded on to the upper axial region of the main shaft 100. The retaining nut 204 is then threaded on to the inner head nut 203. Thereafter, the inner crushing shell 101 is positioned on the head center 201, and the cover plate 205 is mounted on top of the inner crushing shell 101 while having the torch ring 206 disposed in between the cover plate 205 and the inner crushing shell 101. Next, the cover plate 205 is fastened to the retaining nut 204 using the bolts 207 and screws 208 for tightening down the shell 101. The splines 209, 210 present on the contacting surfaces of the cover plate 205 and the retaining nut 204 mechanically engage into a rotational lock. After the tightening of the assembly, the shell 101 will be held onto the head center 201 positioned over its seating surface 202 in the manner illustrated in Figure 3. The torch ring 206 is then burned by application of heat resulting in the welding of the shell 101 and the cover plate 205, thereby completing the process of tightening of the shell 101 on the head center 201 of the crusher.

Claims

Claims:

1. A retainer assembly (102) for securing an inner crushing shell (101) on a shaft mounted head center (201) of a gyratory crusher, the assembly comprising:

a retaining nut (204) having a radially outer surface (213) and a threaded radially inner surface (214) for engaging with an annular inner head nut (203) which is positioned radially around an axial upper region of the shaft (100);

a cover plate (205) with a radially inner surface (215) and a radially outer surface (219), the inner surface (215) being in physical contact with the radially outer surface (213) of the retaining nut (204) and;

a plurality of fasteners (207, 208) for connecting the cover plate (205) to the retaining nut (204);

characterized in that the radially outer surface (213) of the retaining nut (204) is provided with a plurality of projections (209).

2. The retaining assembly (102) as claimed in claim 1 wherein the projections (209) are distributed circumferentially along the outer surface (213) of the retaining nut (204).

3. The retaining assembly (102) as claimed in claim 1 or claim 2 wherein the projections (209) are configured to mechanically engage the cover plate (205) in a rotational lock with the retaining nut (204) in such a way that upon locking the retainer assembly (102) is enabled to press the inner crushing shell (101) between the cover plate (205) and a seating surface (202) of a head center (201) for mounting the inner crushing shell (101) on the head center (201) of the gyratory crusher.

4. The retainer assembly (102) as claimed in any of the preceding claims wherein said assembly further comprises a ring element (206), said ring element being capable of joining together the inner crushing shell (101) and the cover plate (205) on heat treatment.

5. The retainer assembly (102) as claimed in claim 4 wherein said ring element (206) is disposed between the cover plate (205) and the top edge (220) of the inner crushing shell (101).

6. The retainer assembly (102) as claimed in any of the preceding claims wherein said annular inner head nut (203) is provided with a threaded radially outer surface (211) for mechanically engaging with the threaded radially inner surface (214) of the retaining nut (204).

7. The retainer assembly (102) as claimed in any of the preceding claims wherein said retaining nut (204) is eccentric with respect to the longitudinal axis (103) which enables the retaining nut (204) to mechanically engage with the cover plate (205).

8. The retainer assembly (102) as claimed in claim 7 wherein said cover plate (205) and said retaining nut (204) are eccentric with respect to the longitudinal axis (103) to enable mechanical engagement of the plate (205) and the nut (204).

9. The retainer assembly (102) as claimed in any of the preceding claims wherein said cover plate (205) is provided with a plurality of projections (210) on the radially inner surface (215) such that the projections (210) are complementary to the projections (209) on the outer surface (213) of the retaining nut (204) to enable mechanical engagement for rotationally locking the cover plate (205) with the retaining nut (204).

10. The retainer assembly (102) as claimed in any of the preceding claims wherein said projections (209) on the outer surface (213) of the retaining nut (204) are in the form of splines or any other irregular form, which are configured to mechanically engage with the plurality of corresponding projections (210) present on the cover plate (205).

11. The retainer assembly (102) as claimed in any of the preceding claims wherein said retaining nut (204) is provided with a flange (401) projecting radially from the lower end of the nut (204), said flange (401) being configured to enable attaching the fasteners (207) that provide an axial force for pressing the inner crushing shell (101) against the seating surface (202) of the head center (201).

12. The retainer assembly (102) as claimed in any of the preceding claims wherein said cover plate (205) is provided with a plurality of holes (402) for receiving the fasteners (207, 208) which affix the cover plate (205) against the retaining nut (204) and create an axial force on the inner crushing shell (101).

13. The retainer assembly (102) as claimed in any of the preceding claims wherein said retaining nut (204) is provided with a plurality of holes (403) for receiving the fasteners (207) which extend axially downwards from the cover plate (205) to the retaining nut (204) to affix the cover plate (205) against the retaining nut (204).

14. A method for securing an inner crushing shell (101) on a shaft mounted head center (201) of a gyratory crusher using a retaining assembly (102) as claimed in any of the preceding claims, the method comprising:

threading the retaining nut (204) onto the inner head nut (203);

positioning the inner crushing shell (101) on ahead center (201) of the gyratory crusher; mounting the cover plate (205) on top of the inner crushing shell (101) while having a ring element (206) disposed in between the cover plate (205) and the inner crushing shell (101);

fastening the cover plate (205) to the retaining nut (204) using fasteners (207,208) for tightening down the inner crushing shell (101) in such a way that the cover plate (205) is rotationally locked to the retaining nut (204) by means of complementary projections (209, 210) on the surfaces of cover plate (205) and the retaining nut (204) which are in physical contact;

characterized in that the tightened inner crushing shell (101) is affixed to the ring element (206) upon heat treatment.

15. A gyratory crusher comprising:

an elongate main shaft (100) for gyroscopic precession within the crusher;

a head center (201) mounted at the main shaft (100);

an inner crushing shell (101) mounted at the head center (201);

and a retaining assembly (102) as claimed in any of the preceding claims 1-12 configured to mount the inner crushing shell (101) on to the head center (201).