Patent Application
20190308197
The present invention relates to a bearing cartridge to support a rotatable main shaft of a vertical shaft impact (VSI) crusher and in particular, although not exclusively, to a retaining ring forming part of the bearing cartridge to support mounting of the cartridge within the crusher.
Vertical shaft impact (VSI) crushers find widespread use for crushing a variety of hard materials, such as rock, ore, demolished constructional materials and the like. Typically, a VSI crusher comprises a housing that accommodates a rotor mounted at a generally vertically extending main shaft. The rotor is provided with a top aperture through which material to be crushed is fed under gravity from an elevated position. The centrifugal forces of the spinning rotor eject the material against a wall of anvils and/or retained compacted material such that on impact with the anvils/compacted material bed the feed material is crushed to a desired size.
The rotor commonly comprises a horizontal upper disc and a horizontal lower disc. The upper and lower discs are connected and separated axially by a plurality of upstanding rotor wall sections. The top aperture is formed within the upper disc such that the material flows downwardly towards the lower disc between the wall sections and is then ejected at high speed towards the anvils/compacted material bed. A replaceable distributor plate is mounted centrally on the lower disc and acts to protect it from the material feed. Example VSI crushers are described in WO 01/30501, US 2011/0024539 and U.S. Pat. No. 6,171,713.
Conventionally, the main shaft that supports and provides rotational drive to the rotor is mounted within the crusher via a bearing cartridge. The cartridge houses internal roller and thrust bearings to guide and stabilize the rotating main shaft. The bearing cartridge is typically mounted at a drum forming a part of the frame of the crusher and in particular is supported at an axial ends of the drum via an upper annular neck and lower annular skirt.
The cartridge is rotationally locked to the drum and hence the crusher frame via an upper flange bolted to the annular neck and a lower retaining ring bolted to the annular skirt. Conventionally, the retaining ring is formed by two tapered steel rings having opposed wedging surfaces fitted back-to-back about the main shaft. As one of the wedges is clamped against the skirt by the bolts, the opposite wedge is forced against the outside surface of the bearing cartridge to rotationally lock the cartridge within the drum. However, such conventional arrangements are disadvantageous for a number of reasons. In particular, over tightening of the retaining ring bolts forces the ring radially inward against the cartridge to an extent that the running clearance of the internal bearings is reduced. Additionally, existing retaining rings typically seize at the cartridge and/or the skirt making maintenance of the lower drive components of the crusher difficult. Furthermore, conventional bearing cartridges are difficult and inconvenient to install and remove at the crusher frame given the restricted access at the lower internal region of the crusher. The installation of a multi-component retaining ring is often problematic and increases the operational downtime of the crusher. Accordingly, what is required is a bearing cartridge and a retaining ring that addresses these problems.
It is an objective of the present invention to provide a bearing cartridge for a vertical shaft impact (VSI) crusher having a retaining or support ring that eliminates the risk and occurrence of unintentionally reducing an internal running clearance of bearings of the cartridge that support the main shaft. It is a further specific objective to provide a bearing cartridge having component parts and including in particular a retaining or support ring to mount the cartridge at the crusher frame that reduces or eliminates the risk of the bearing cartridge and its component parts seizing to one another and/or the support frame so as to greatly facilitate insulation, servicing and removal of the bearing cartridge at the crusher.
It is a yet further specific objective to provide a retaining ring for a bearing cartridge configured to lock in position via a predetermined locking force so as to eliminate damage or undesirable change to other components of the bearing assembly and crusher that may reduce the operating performance and efficiency of the crusher. It is a further specific objective to provide a retaining ring for a bearing cartridge configured to withstand high operating temperatures without undesirable expansion and detrimental thermal transfer characteristics. It is a general objective of the present invention to reduce the overall weight of the crusher as far as possible without compromising the integrity and operational lifetime of the crusher.
The objectives are achieved by providing a bearing cartridge to support a rotatable main shaft of a VSI crusher that comprises a single piece retaining ring to support mounting of the cartridge within the crusher and to stabilise the cartridge during dynamic rotation of the main shaft. The subject invention is advantageous via the single piece retaining ring to specifically eliminate the risk and occurrence of undesirable reduction of the running clearance of the bearings. In particular, the present retaining ring is configured specifically so as to be incapable of being forced radially inward onto a main housing of the bearing cartridge that would otherwise distort the housing radially inward and accordingly reduce the running clearance of the internal thrust and/or roller bearings. In particular, the inventors have identified that mounting and axially and rotationally locking the cartridge at the crusher mainframe (i.e., drum) at an upper axial region is sufficient such that the axially lower retaining ring functions to laterally stabilise the bearing cartridge within the drum. That is, the present retaining ring is not configured to rotationally clamp onto the outside surface of the bearing housing to any significant extent so as to be rotationally locked to the housing according to the conventional multi-component wedge retaining rings. The present mounting arrangement is advantageous to eliminate transmission of vibrational forces from the rotating main shaft to the crusher frame which in turn reduces operating noise, component wear and accordingly increases the strength of mounting of the bearing cartridge within the crusher.
According to a first aspect of the present invention there is provided a bearing cartridge to support a rotatable main shaft of a vertical shaft impact (VSI) crusher, the cartridge comprising: an elongate housing defining an internal chamber to receive a part of the main shaft of the crusher; an annular flange projecting radially outward from the housing at or towards a first axial end of the housing to seat within an annular neck of a frame part of the crusher; and a retaining ring releasably mountable to an external facing surface of the housing at or towards a second axial end of the housing to seat within an annular skirt of the frame part; characterised in that: the retaining ring is a single piece ring extending radially between the skirt and the housing.
Preferably, an external facing surface of the ring is in contact with a radially inward facing surface of the skirt and a radially inward facing surface of the ring is in contact with the external facing surface of the housing such that the ring extends completely between the skirt and the housing. Advantageously, the present ring is not split or divided in a radial direction but is formed as a single body extending radially continuously between the internal facing surface of the skirt and the external facing surface of the housing. The present ring comprises a material having a desired rigidity and malleability so as to not expand radially when placed under axial compression by attachment bolts. That is, the present ring is capable of being deformed to a slight degree in the radial direction so as to increase the frictional contact of the ring with the radially adjacent skirt (at the external facing surface) and housing (at the internal facing surface). Importantly, the present ring by its single-piece construction is not configured to be compressed radially onto the housing that would otherwise reduce the internal diameter of the housing and accordingly the running clearance of the internal bearings.
Preferably, the ring comprises bolt bores extending axially through the ring to receive bolts to releasably secure the ring to the skirt. Preferably, the ring comprises six to eight bores distributed uniformly in a circumferential direction around the ring. Preferably, the ring further comprises at least one axially extending pilot bore being separate to the bolt bores to receive axially a release screw or bolt. More preferably, the ring comprises a plurality or pilot bores including preferably two to four pilot bores. Optionally, a diameter of the pilot bores is less than a diameter of the bolt bores.
Optionally, the ring comprises an external facing surface that is divided axially to have a first axial section having a first outside diameter and a second axial section having a second outside diameter that is greater than the outside diameter of the first section. The ring may comprise a tapered shoulder at the external facing surface at the axial junction between the first and second axial sections. Preferably, the shoulder comprises an annular surface aligned transverse to the external facing surface of the ring at the first and second axial sections with the surfaces at these sections being aligned parallel to a longitudinal axis extending through the bearing cartridge, the main shaft and a rotor of the VSI crusher.
Preferably, the outside diameter of the second axial section is in a range +/−1 to 2 mm of the internal diameter of the skirt. That is, and preferably the outside diameter of the second section is approximately equal to an inside diameter of an inward facing surface of the skirt such that the ring is securable within the skirt by interference friction fit. Accordingly, the present retaining ring may be inserted and is capable of being held exclusively radially between the housing and the skirt via the frictional contact between the ring and the housing and the skirt. Such a configuration is advantageous to facilitate installation of the retaining ring into the skirt from within the confined space at the lower region of the crusher frame.
Preferably, the ring is a split ring having a discontinuation or break in a circumferential direction around the ring to enable the ring to be expanded radially. Such an arrangement is advantageous to temporarily expand the ring radially by inserting a tool into the region of the split to allow the ring to be slid over a bottom cover of the bearing cartridge and into position about the housing. Additionally, this configuration also facilitates removal of the ring once the retaining bolts have been removed.
Optionally, the ring comprises a non-ferrous metal. Optionally, the ring comprises an aluminium or aluminium alloy. Optionally, the ring may comprise a thermoplastic material, a polymer material or a polyamide based material. Preferably, the ring comprises a nylon.
A nylon ring is advantageous to provide a desired preloading force when compressed to locate radially between the housing and the skirt. A polymer based material will avoid seizing of the ring to the housing of the surrounding drum which is a problem with conventional designs. Additionally, a polymeric material is incapable of being compressed radially onto the outside surface of the housing to an extent that would distort the metal housing radially inward and reduce the running clearance of the bearings. A polymer based retaining ring is further advantageous to withstand high operating temperatures encountered during use and to minimise or eliminate expansion and heat transfer problems.
Optionally, the retaining ring is self-lubricating and does not require grease or oil. A polymeric retaining ring is accordingly lighter than conventional arrangements to contribute to a reduction in the overall weight of the crusher being a general objective of the present invention. The present ring is further advantageous by the choice of material to be retained radially between the housing and the skirt of the frame drum by a friction interference fit. This friction fit is achieved via the desired deformable characteristic of the ring when pushed axially into a pocket region defined between the housing and the skirt. Such an arrangement greatly facilitates mounting and disassembly of the bearing cartridge at the crusher particularly given the confined space available to personnel when fitting and removing the bearing cartridge via sets of bolts.
According to a second aspect of the present invention there is provided a vertical shaft impact crusher comprising a bearing cartridge as described and claimed herein.
Optionally, the crusher comprises a mainframe, the mainframe including the annular neck and the annular skirt, the frame further comprising a drum connecting axially the neck and the skirt, wherein the housing extends within the drum axially between the neck and the skirt. Preferably, the mainframe further comprises wings projecting radially outward from the drum and extending axially between the annular neck and skirt. Optionally, the crusher comprises four axially and radially extending wings. Preferably, the rings project radially outward beyond the drum by a distance greater than that by which the annular neck and skirt project radially from the drum.
Preferably, the ring is mounted substantially at the same axial position as a bearing assembly located radially between the housing and the main shaft of the crusher. Accordingly, and preferably the bearing cartridge is mounted at the drum at an upper axial end and a lower axial end of the cartridge and in particular the cartridge housing. Such arrangement facilitates the secure mounting and stabilisation of the cartridge within the frame to eliminate lateral movement and reduce or eliminate the transmission of vibrational forces.
The present retaining ring formed from a thermoplastic polymer material is advantageous to reduce and preferably eliminate transmission of vibrational forces from the cartridge to the crusher mainframe (and in particular the annular skirt). Accordingly, the present ring may be considered to provide absorption of vibrational forces and to provide a relatively flexible mounting gasket between the cartridge and the mainframe relative to conventional steel retaining ring arrangements.
According to a further aspect of the present invention there is provided a retaining ring to support mounting of a bearing cartridge at a vertical shaft impact crusher, the retaining ring comprising: a single piece body having a radially inward facing surface, a radially outward facing surface and respective first and second end faces; wherein the ring comprises a non-ferrous or polymeric material.
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:
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The single body of ring 35 is broken or discontinuous in a circumferential direction such that ring 35 may be considered to be a split ring having a first end 41a and a second end 41b in a circumferential direction. The respective first and second ends 41a, 41b are positioned opposed to one another to define a gap region 55. Such a configuration is advantageous to facilitate installation of ring 35 into the pocket between skirt 14 and housing 45. In particular, a suitable tool (e.g., a screwdriver) may be inserted into gap region 55 so as to ‘spread’ ring 35 slightly to allow it to pass axially over end plate 34 at to slide axially over housing 45 into position within the skirt pocket.
Ring radially outward facing surface 28 is divided into a first axial upper section 42 and a second axial lower section 43. Each section 42, 43 is separated axially by a shoulder transition section 44. First section 42 comprises a first outside diameter (OD) and second section 43 comprises a second OD being greater than that of the first section 42. Accordingly, transition section 44 is formed as a shoulder that provides a tapering OD transition from the smaller OD of first section 42 to the larger OD of second section 43. The dual OD configuration of ring 35 facilitates insertion of the ring 35 into the pocket between skirt 14 and housing 45 whilst also facilitating an axial and radial secure fit of ring 35 between cartridge 10 and drum 12. Such a configuration is advantageous during initial assembly and final disassembly procedures as ring 35 once introduced into internal region of skirt 14 is self-retaining at drum 12 so as to greatly facilitate manual introduction and tightening of bolts 33 within the confined space at the lower region the VSI crusher. According to the specific implementation, an axial length of first axial section 42 is greater than that of second axial section 43 such that a majority of the axial length of ring 35 between faces 37 and 38 may be introduced into the internal region of skirt 14 before second section 43 is forced into abutment contact against skirt inward facing surface 29 to frictionally hold ring 35 about housing 45. Advantageously, ring 35 is formed from a thermoplastic polymer material having an appropriate hardness and plasticity (malleability) to greatly facilitate installation, extraction and the axial and radial support of bearing cartridge 10 at drum 12. In particular, and according to the specific implementation, ring 35 comprises a nylon material having a Shore D hardness (at 22° C.) in a range 70 to 90 according to International Standard ASTM D2240. Additionally, ring 35 may comprise a compressive strength (10% deformation, 22° C.) of 80 to 90 MPa according to ASTM D695. A thermoplastic material is advantageous to withstand higher operating temperatures as housing 45 is heated by the frictional contact of the internal bearings 26, 27 mounted within chamber 32. Additionally, ring 35 exhibits minimal expansion and thermal transfer between housing 45 and mainframe 11. The deformation characteristic of ring 35 is further beneficial to absorb the vibrational forces received from housing 45 due to the rotational motion of main shaft 15 and bearings 26, 27. The material choice of ring 35 is further advantageous to avoid seizing within the skirt 14 and at the external surface 30 of housing 45.
By forming ring 35 as a single piece body to bridge completely the pocket between skirt surface 29 and housing surface 30, ring 35 eliminates the risk and occurrence of the ring unintentionally compressing radially onto housing external facing surface 30 which may otherwise act to radially compress the region of housing 45 at the axial position of skirt 14 and reduce the running clearance of bearings 26 and 27. As will be appreciated, bearings 26 and 27 typically comprise thrust and roller bearings which require a predetermined radial clearance between main shaft 15 and housing internal facing surface 31. Whilst ring 35 is capable of being clamped axially to skirt 14, it is configured to expand radially to only a small extent sufficient to achieve a frictional lock against housing external facing surface 30 and skirt internal facing surface 29 as bolts 33 are tightened.
Advantageously, the present bearing cartridge 10 is axially and rotationally locked at drum 12 exclusively via flange 21 and annular neck 13. That is, ring 35 whilst being radially locked at annular skirt 14 is incapable of being rotationally coupled/locked at the external facing surface 30 of housing 45. In particular, ring 35 is independently rotationally mounted at housing 45. That is, ring 35 advantageously provides support and stabilisation of housing 45 within drum 12 to prevent lateral (radial) movement of housing 45 at its lower end 25 relative to drum 12. Effectively, bearing cartridge 10 is suspended axially from and rotationally locked to drum 12 exclusively via the seating and clamping of flange 21 at neck 13.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/063895 | 6/16/2016 | WO | 00 |
