EP2929940A1

EP2929940A1 - Inner crushing shell retaining assembly

Info

Publication number: EP2929940A1
Application number: EP14164015.1A
Authority: EP
Inventors: Kim Kotkamaa; Thomas Ohlsson
Original assignee: Sandvik Intellectual Property AB
Current assignee: Sandvik Intellectual Property AB
Priority date: 2014-04-09
Filing date: 2014-04-09
Publication date: 2015-10-14

Abstract

A retainer assembly (102) to releasably secure a mantle at a head centre of a gyratory crusher. The retainer assembly comprises a modular construction having primarily a first head nut (203) having an eccentric part to engage with an eccentric region of the mantle. A locking ring (201) is driven axially downward by rotation of the head nut to compress the mantle onto the head centre.

Description

Field of invention

The present invention relates to a retainer assembly for securing an inner crushing shell on a main shaft mounted head centre of 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 centre mounted upon an elongate main shaft. A first crushing shell (typically referred to as a mantle) is mounted on the head centre and a second crushing shell (typically referred to as a 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 centre to perform a gyratory pendulum movement and crush the material introduced in the crushing chamber.
With use, the inner and outer crushing shells become worn and require replacement at regular intervals. It is therefore important to provide a retaining mechanism for convenient releasable mounting of the shells at the crusher frame and the head centre. A variety of different assemblies have been proposed for mounting the inner crushing shell at the main shaft in an attempt to both provide a reliable lock and convenient mounting and dismounted of the mantle. Example inner shell retaining arrangements are described in US 7,216,823 ; EP 1581344 ; WO 2013/009531 . However, conventional arrangements are still disadvantageous as it is typically required to use a cutting blowpipe and sledge hammer for removal and in some instances the assemblies cannot handle adequately the significant torques induced during crushing.
EP 2535110 attempts to address the above problems via 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. However, such an arrangement must still withstand the significant forces transmitted through the assembly. In particular, significant shear forces are generated within the retaining assembly of EP 2535110 and this can reduce the operational lifetime of certain components of the assembly or if a component fails cause significant damage and crusher downtime. Accordingly, what is required is a mantle retainer assembly that addresses the above problems.

Summary of the Invention

It is an objective of the present invention to provide a mantle retainer assembly for securing an inner crushing shell on a head centre at a main shaft that allows both convenient attachment and detachment of the mantle whilst being resistant to the significant loading forces transmitted through the assembly during use. Accordingly, it is a further specific objective to minimise the risk of failure of the assembly and to extend as far as possible the service lifetime of the various assembly component parts. It is a further objective to provide a retainer assembly that also enables convenient insertion and removal of the mantle at the head centre involving the lowering and raising of the mantle with conventional lifting apparatus during mantle replacement or servicing.
It is a further specific objective to provide a mantle locking arrangement that is sealed against dust and debris material in which the strength of the seal is enhanced by the rotational motion of the crusher.
At least some of the objectives are achieved, in part, by component parts of the assembly that abut one another to provide a frictional lock between i) the mantle and the retainer assembly and ii) the various components of the retainer assembly such that the arrangement is self-tightening and is resistant to the significant loading forces (torques and in particular shear forces) transmitted through the locking arrangement.
According to a first aspect of the present invention there is provided a retainer assembly for securing an inner crushing shell on a shaft mounted head of a gyratory crusher, the assembly comprising: a first head nut having a first surface to be generally inward facing towards a main shaft of the crusher and a second surface to be generally radially outward facing towards an axial upper region of the shell, the second surface being eccentric relative to the first surface to mate with and frictionally lock against an eccentric radially inward facing surface at the upper region of the shell; a locking ring for positioning axially on top of the first head nut; a plurality of bolts extending axially between and configured to couple rotational movement of the first head nut and the locking ring; characterised by: at least one abutment member extending axially between and rotationally coupling the first head nut and the locking ring in at least one rotational direction relative to a central axis, the abutment member being additional to and configured to protect each of the bolts from a shear force resultant from a torque acting on the first head nut.
Reference within this specification to an 'abutment member' encompasses all manner of configurations extending in the axial direction between the first head nut and the locking ring to rotationally lock the nut and the ring in at least one rotational direction. The abutment member may comprise an axially extending flange formed integrally or non-integrally with either the head nut or locking ring to engage onto or into the alternate locking ring or head nut. In one aspect, the abutment member may comprise a step-like configuration or castellation(s) formed at the head nut and/or locking ring. This term also encompasses one or a plurality of pins, wedges, lugs and other elongate protrusions extending axially between the head nut or locking ring. The abutment member is an additional component to all of the bolts so as to protect each of the bolts from shearing.
Optionally, the abutment member comprises at least two pins extending axially between the first head nut and the locking ring. Preferably, the first head nut comprises a plurality of holes or grooves and the pins extend from the locking ring to be received respectively in each of the holes or grooves. Such an arrangement is advantageous to allow the convenient coupling or decoupling of the locking ring at the first head nut. The holes or grooves formed in the head nut are allow beneficial to convenient coupling of a lifting tool used to raise and lower the head nut and in particular the mantle into position at the head centre.
Preferably, the holes or grooves comprise a larger cross section than each of the pins to allow the pins to be inserted within and withdrawn from the holes or grooves by axial movement of the locking ring relative to the first head nut. The holes or grooves may be sized so as to be compatible with a variety of different lifting tool configurations whilst providing the necessary abutment against the locking pins. Optionally, the retainer assembly may comprise between two to six of the pins or more preferably three pins. Preferably, the pins (and the holes or grooves) are distributed substantially uniformly in a circumferential direction around the nut and/or locking ring.
Preferably, the retainer assembly further comprises an axially extending annular flange provided at a radially outer perimeter region of the locking ring to mate against a part of the upper region of the shell to provide a substantially sealed annular contact between the locking ring and the shell. Due to the configuration of the assembly, the annular flange is compressed axially downward onto the upper region of the mantle via the self-tightening function. Accordingly, the seal strength to prevent dust and dirt ingress into the region of the head centre is increased via the rotation of the mantle during use of the crusher.
Preferably, the retainer assembly further comprises a second head nut for positioning radially intermediate the main shaft and the first head nut, the second head nut comprising threads provided respectively on a first surface being radially inward facing and a second surface being radially outward facing; and the first head nut comprising threads on the first surface to mate with the threads on the second surface of the second head nut. The second head nut is beneficial to protect the main shaft by representing an intermediate body between the first head nut and the shaft. Should the threads of the second head nut become damaged or worn, this component may be readily replaced without affecting the main shaft.
Preferably, the second head nut comprises an axial length configured to overlap axially the first head nut and the locking ring such that an axial region of the second head nut and the locking ring are provided in touching or near touching contact. The axial overlap is effective to increase the sealing of the inner components of the retainer assembly and head centre from dust and debris. To further enhance the seal strength, the retainer assembly may further comprise an annular groove provided at the second surface of the second head nut or a radially inward facing surface of the locking ring; and an o-ring accommodated within the groove to be positioned radially between the second head nut and the locking ring. Preferably, the groove is formed in the second head nut and the o-ring is interchangeably mounted within the groove.
Preferably, the assembly further comprises a cover ring positionable on top of the locking ring; and a plurality of bolts extending axially between and configured to rotationally couple the cover ring and the first head nut and/or the locking ring. The cover ring is effective to protect the cover ring and the various coupling bolts extending between the cover ring and the first head nut.
Preferably, the assembly further comprises a plurality of spring washers to provide a couple between a bolt head of each of the bolts and the locking ring. The washers are effective to prevent the bolts stretching axially in response to the tensile force created as the first head nut is drawn axially downward by the rotating mantle. As will be appreciated, alternative configurations of washers or spacers may be suitable and configured to resist or cushion the tensile forces transmitted through the bolts by the axial downward movement of the first head nut.
Advantageously, the retainer assembly may further comprise an alignment marker provided at a radially outer facing region of the locking ring for alignment with a region or marker of the shell. Such an arrangement allows the convenient alignment of the locking ring with the mantle so as to ensure the eccentric faces of the first head nut and the mantle are appropriately positioned to self-tighten the mantle onto the head nut during rotation.
Optionally, the locking ring may further comprise a plurality of bores, a part of an axial length of each of the pins being locked within each of the bores by frictional locking contact. Such an arrangement may be advantageous for manufacturing and assembly of the locking ring and pins being non-integrally formed. The locking pins may be interchangeable and replaced at the locking ring should they become damaged or worn during use.
According to a second aspect of the present invention 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 retainer assembly as claimed herein configured to releasably mount the shell on 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 (mantle) suitable for gyroscopic precession within a gyratory crusher, the mantle secured at the main shaft via a retainer assembly according to a specific implementation of the present invention;
Figure 2 is a perspective cross sectional view through the retainer assembly of figure 1;
Figure 3 is a further cross sectional perspective view of the retainer assembly of figure 1 with the cover ring removed for illustrative purposes;
Figure 4 is a further cross sectional perspective view of the retainer assembly of figure 1 with the cover ring removed for illustrative purposes;
Figure 5 is a further cross sectional perspective view of the retainer assembly of figure 1;
Figure 6 is a further cross sectional perspective view of the retainer assembly of figure 1;
Figure 7 is a further cross sectional perspective view of the retainer assembly of figure 1 with the cover ring removed for illustrative purposes;
Figure 8 is an external perspective view of the retainer assembly of figure 1 with the inner crushing shell removed for illustrative purposes;
Figure 9 is an underside view of the retainer assembly of figure 8 independent of the main shaft and head centre.

Detailed description of preferred embodiment of the invention

Referring to figures 1 and 2, an inner crushing shell (mantle) 103 of a gyratory crusher is mounted at a generally conical head centre 204 that is in turn mounted to surround a lengthwise region of a main shaft 100. Shaft 100, as will be appreciated, is rotatably driven by suitable drives and gears (not shown) to precess within the crusher to displace shell 103 radially relative to an outer crushing shell (not shown). Mantle 103 is releasably retained at head centre 204 via a retainer assembly indicated generally by reference 102. Retainer assembly 102 is generally concentric relative to mantle 103 and main shaft 100 so as to be centred on a longitudinal axis 101 extending through main shaft 100.
Retainer assembly 102 comprises a modular construction formed from a first head nut 203; a locking ring 201; a cover ring 200 and a second head nut 205. Referring to figure 5, second head nut 205 is generally annular and comprises a radially inward facing surface 209 provided with threads to cooperate with corresponding threads provided at a radially outer facing surface 208 of main shaft 100. Second head nut 205 represents a radially innermost part of retainer assembly 102. First head nut 203 is also generally annular and comprises a radially inward facing surface 504 comprising threads to cooperate with a part of a radially outward facing surface 505 of second head nut 205 that also comprises threads. A radially outward facing surface 207 of first head nut 203 is positioned in tight frictional contact with a radially inward facing mantle surface 206 at an axially upper region 210 of mantle 103. Locking ring 201 is positioned axially above first head nut 203 and is also annular to be positioned radially outside and surround an axially upper region of second head nut 205. A radially inward facing surface 502 of locking ring 201 is positioned in close touching contact with a radially outer facing surface 503 at the axially upper region of second head nut 205. Cover ring 200 is positioned immediately on top of locking ring 201 and is also dimensioned to sit in close touching contact against the radially outward facing head nut surface 503.
First head nut inner surface 504 is centred on axis 101 and is concentric relative to second head nut 205 and main shaft 100. The radially outer head nut surface 207 is eccentric relative to second head nut 205 and shaft 100 such that a radial thickness of first head nut 203 is non-uniform in a circumferential direction around axis 101. Additionally, mantle inner surface 206 is also eccentric relative to shaft 100 and axis 101 and comprises a radius of curvature corresponding to that of head nut surface 207. All other components (200, 201, 205) of retainer assembly 102 are concentric relative to shaft 100 and axis 101.
Retainer assembly 102 further comprises a first set of retaining bolts 301 that extend axially to rotationally couple locking ring 201 and first head nut 203. According to the specific implementation, assembly 102 comprises nine bolts 301 distributed uniformly in a circumferential direction around axis 101. Referring to figures 3 and 4, each bolt 301 comprises a head 401 and an elongate shaft 400. A plurality of recesses 302 extends axially downwardly from an upper surface of locking ring 201 and are dimensioned to receive bolt heads 401 and a plurality of spring washers 402. Washers 402 are positioned axially between each head 401 and a trough surface 403 of recess 302. A bore 404 extends through the axially lower region of ring 201 to receive shaft 400. Similarly, a plurality of bores 303 extend axially through first head nut 203 to receive the lower ends of each bolt shaft 400. Accordingly, bolts 301 provide discrete axial bridges to rotationally couple ring 201 and first head nut 203. Bore 303 and an outer surface of shaft 400 are threaded as will be appreciated.
Referring to figures 3 and 6, cover ring 200 is rotationally locked to the axially lower locking ring 201 and first head nut 203 via a second set of locking bolts indicated generally by reference 300. According to the specific implementation, assembly 102 comprises three bolts that extend axially between cover ring 200 and first head nut 203. The bolts 300 of the second set each comprise a corresponding head 602 and an elongate shaft 601. The axial length of shaft 601 of the second set is greater than the axial length of the shaft 400 of the first set whilst a radius of shafts 400 is greater than that of shafts 601. Locking ring 201 further comprises a plurality of bores 603 to receive shafts 601 and first head nut 203 also comprises a corresponding set of bores 600 to receive an axial end of each shaft 601. Each bore 600 also comprises corresponding threads to cooperate with threads provided at shaft 601.
Referring to figures 7 to 9 assembly 102 further comprises a plurality of abutment members in the form of elongate pins 700 each having a generally cylindrical shape profile. Pins 700 extend axially between locking ring 201 and first head nut 203. Accordingly, locking ring 201 further comprises a further set of bores 702 having a radius approximately equal to a radius of each pin 700 to lock each pin 700 by close-fitting frictional contact within each bore 702. Each pin 700 is further secured by welding. Each pin 700 extends axially downward from locking ring 201 to be received within a plurality of grooves 701 that are recessed radially inward from the radially outer surface 207 of first head nut 203. Each groove 701 comprises a cross section in a plane perpendicular to axis 101 that is greater than a radius of each pin 700. Accordingly, pins 700 may be readily inserted and removed within each corresponding groove 701 via axial displacement of locking ring 201 relative to first head nut 203. According to the specific implementation, assembly 102 comprises three pins 700 and three corresponding grooves 701 within first head nut 203. Each pin 700 is configured to form an axially extending bridge to rotationally couple locking ring 201 and first head nut 203.
Referring to figure 5, an annular channel 500 extends a relatively short distance radially inward within the axially upper region of second head nut 205 from radially outer surface 503. Channel 500 is accordingly positioned at the same axial location as the locking ring radially inner surface 502. An o-ring 501 is accommodated within channel 500 so as to be provided in a close fitting and compressed configuration radially intermediate the upper region of second head nut 205 and locking ring 201. Locking ring 201 further comprises a relatively short axially extending flange 506 provided at a radially outer perimeter region. Flange 506 projects axially downward from an axially lower and downward facing surface 508 of locking ring 201. Annular flange 506 is configured to mate in close touching contact against mantle upper region 210 and in particular an annular shoulder 507 to form an interlocked step-like joint between locking ring 201 and mantle upper region 210.
To mount mantle 103 at head centre 204, second head nut 205 is first assembled onto main shaft 100 via cooperation between the threads at respective surfaces 208, 209. First head nut 203 is then mounted onto second head nut 205 via cooperation of the screw threads at respective surfaces 504, 505. Mantle 103 is lowered into position onto head 204 such that the corresponding eccentric head nut and mantle surfaces 207, 206 are aligned in close fitting frictional contact. Lifting and lowering of mantle 103 is achieved by a dedicated lifting tool that engages and is secured within head nut grooves 701. O-ring 501 is then seated in position followed by seating of locking ring 201 onto first head nut 203. Ring 201 is lowered or raised within the crusher via lifting eyelets (not shown) releasably secured to a third set of bores 304 provided at an axially upper region of locking ring 201. During lowering of locking ring 201 onto head nut 203, pins 700 engage into grooves 701. Locking ring 201 is bolted into position via the first set of bolts 301. Cover ring 200 is then placed over locking ring 201 and secured in position via the second set of bolts 300 that also engage into first head nut 203.
Retainer assembly 102 is configured to be self-tightening so as to compress axially mantle 103 onto head centre 204 via rotation of the mantle 103 within the crusher. In particular, as the mantle starts to rotate, head nut 203 follows the rotation due to the cooperating eccentric surfaces 206, 207. The rotating first head nut 203 is then screwed axially downward along the axially lower region of second head nut 205 via engagement between surfaces 504, 505. Accordingly, locking ring 201 is also driven axially downward by the coupled rotation with head nut 203 via bolts 301. Accordingly, bolts 301 are tightened which acts to press locking ring 201 axially downward onto mantle 103 and in particular increase the contact force between flange 506 and mantle shoulder 507 and locking ring surface 508 and mantle upper region 210. Mantle 103 is also pressed axially downward onto head 204 to achieve the self-tightening strong friction fit.
Spring washers 402 act to prevent bolts 301 from being stretched axially due to the tensile forces created as first head nut 203 is driven axially downward. The eccentric coupling of first head nut 203 and mantle 103 that provides the axial compression of the retainer assembly 102 is advantageous to maximise the seal provided at by the flange 506 and o-ring 501. That is, dust and particle debris is effectively prevented from passing axially downward and radially inward beyond the assembly 102 and towards head centre 204. Dust ingress into the region surrounding head centre 204 is particularly disadvantageous due to the location of the various drive components and shaft bearings positioned immediately below head centre 204.
Attachment of the cover ring 200 to the first head nut 203 via the second set of bolts 300 also ensures cover ring 200 is driven axially downward by the rotation of mantle 103 to effectively protect locking ring 201 from the crushable material falling onto mantle 103.
Due to the significant torques generated within the crusher, pins 700 are effective to provide primary rotation locks between locking ring 201 and first head nut 203. Pins 700 act to isolate or to minimise shear forces imparted to bolts 301 (and also bolts 300) due to the rotation of mantle 103 and the induced rotation of first head nut 203. In certain applications and/or following extended use, without pins 700, bolts 301 would be susceptible to shearing at shafts 400. Pins 700 are further advantageous to minimise the number of bolts 301 which is advantageous to provide rapid and convenient interchange of a worn mantle 103 so as to reduce crusher downtime. Mantle 103 may be quickly and conveniently orientated in position at first head nut 203 by alignment of a first marker 104 provided at a perimeter of locking ring 201 and a corresponding marker 105 provided at mantle upper region 210.
According to further specific implementations, one or a plurality of axially extending projections or stepped regions may be provided at locking ring surface 508 to engage and abut corresponding projections or stepped regions provided at an axially upper surface 509 of first head nut 203. Such interlocking and overlapping abutments, as will be appreciated, act in a similar manner to the axial bridging pins 700 to rotationally couple locking ring 201 and first head nut 203 in at least one rotational direction about axis 101. Such configurations may include male and female type lugs, castellations, tong and groove arrangements or any manner of surface profiling extending axially between surfaces 508 and 509 to prevent independent rotation of locking ring 201 and first head nut 203.

Claims

A retainer assembly (102) for securing an inner crushing shell (103) on a shaft mounted head (204) of a gyratory crusher, the assembly (102) comprising:
a first head nut (203) having a first surface (504) to be generally inward facing towards a main shaft (100) of the crusher and a second surface (207) to be generally radially outward facing towards an axial upper region (210) of the shell (103), the second surface (207) being eccentric relative to the first surface (504) to mate with and frictionally lock against an eccentric radially inward facing surface (206) at the upper region (210) of the shell (103);

a locking ring (201) for positioning axially on top of the first head nut (203);

a plurality of bolts (301) extending axially between and configured to couple rotational movement of the first head nut (203) and the locking ring (201);

characterised by:
at least one abutment member (700) extending axially between and rotationally coupling the first head nut (203) and the locking ring (201) in at least one rotational direction relative to a central axis (101), the abutment member (700) being additional to and configured to protect each of the bolts (301) from a shear force resultant from a torque acting on the first head nut (203).
The assembly as claimed in claim 1 wherein the abutment member (700) comprises at least two pins extending axially between the first head nut (203) and the locking ring (201).
The assembly as claimed in claim 2 wherein the first head nut (203) comprises a plurality of holes or grooves (701) and the pins extend from the locking ring (201) to be received respectively in each of the holes or grooves (701).
The assembly as claimed in claim 3 wherein each of the holes or grooves (701) comprise a larger cross section than each of the pins to allow the pins to be inserted within and withdrawn from the holes or grooves (701) by axial movement of the locking ring (201) relative to the first head nut (203).
The assembly as claimed in any one of claims 2 to 4 comprising between two to six of the pins.
The assembly as claimed in claim 5 comprising three of the pins.
The assembly as claimed in any preceding claim further comprising an axially extending annular flange (506) provided at a radially outer perimeter region of the locking ring (201) to mate against a part (507) of the upper region (210) of the shell (103) to provide a substantially sealed annular contact between the locking ring (201) and the shell (103).
The assembly as claimed in any preceding claim further comprising a second head nut (205) for positioning radially intermediate the main shaft (100) and the first head nut (203), the second head nut (205) comprising threads provided respectively on a first surface (209) being radially inward facing and a second surface (505) being radially outward facing; and
the first head nut (203) comprising threads on the first surface (504) to mate with the threads on the second surface (505) of the second head nut (205).
The assembly as claimed in claim 8 wherein the second head nut (205) comprises an axial length configured to overlap axially the first head nut (203) and the locking ring (201) such that an axial region of the second head nut (205) and the locking ring (201) are provided in touching or near touching contact.
The assembly as claimed in claim 9 further comprising an annular channel (500) provided at the second surface (503) of the second head nut (205) or a radially inward facing surface (502) of the locking ring (201); and
an o-ring (501) accommodated within the channel (500) to be positioned radially between the second head nut (205) and the locking ring (201).
The assembly as claimed in any preceding claim further comprising:
a cover ring (200) positionable on top of the locking ring (201); and

a plurality of bolts (300) extending axially between and configured to rotationally couple the cover ring (200) and the first head nut (203) and/or the locking ring (201).
The assembly as claimed in any preceding claim further comprising a plurality of spring washers (402) to provide a couple between a bolt head (401) of each of the bolts (301) and the locking ring (201).
The assembly as claimed in any preceding claim further comprising an alignment marker (104) provided at a radially outer facing region of the locking ring (201) for alignment with a region or marker (105) of the shell (103).
The assembly as claimed in any preceding claim when dependent on claim 2 wherein the locking ring (201) comprises a plurality of bores (702), a part of an axial length of each of the pins being locked within each of the bores (702) by frictional locking contact.
A gyratory crusher comprising:
an elongate main shaft (100) for gyroscopic precession within the crusher;

a head (204) mounted at the main shaft (100);

an inner crushing shell (103) mounted at the head (204); and

a retainer assembly (102) as claimed in any preceding claim configured to releasably mount the shell (103) on the head (204).