The present invention relates to a split ring component. Although applicable to other circumstances, the preferred arrangement of the invention relates to a split cage for a bearing such as a split roller bearing.
As is well-known, bearings for shafts normally comprise an outer race mounted in a housing, and an inner race mounted to rotate with the shaft, and rolling elements placed between the inner and outer races. The rolling elements of the bearing may be in the form of rotating balls which are mounted in a cage, or, as will be described in relation to this preferred arrangement of the invention, rollers, which once again are mounted in a cage between the inner and outer races.
In order to maintain the bearing, that is to replace worn components or the like, it is often preferable to be able to remove the races and rolling elements from the shaft without removing the shaft and this can be done by providing a split outer housing, that is an outer housing which surrounds the shaft but which is split in a plane parallel to the axis of the shaft (typically horizontally so that the upper half of the outer housing may be removed for servicing), similarly split inner and outer races and similarly the cage mounting the rolling elements may also be split in a plane which is parallel to the axis of the shaft.
In some simple arrangements, it may be sufficient to provide the cage in the form of two moulded or otherwise manufactured semi-circular components.
Sometimes, it is preferred to make the cage as an annulus, and then to split the cage. It is necessary to cut the cage in some way or another to split it and this can be carried out in various ways. Typically, the cut may be by means of various blades. In a more sophisticated arrangement, the cut may be provided by spark erosion by means of, for example, a wire of an electrical discharge machining (EDM) apparatus which passes through the ring.
All of these splitting processes require the removal of some metal, and consequently when the two halves of the cage are reassembled, they no longer form a perfect circle. This may be overcome in a variety of ways, for example, by holding the two halves together by means of clips which include a spacer which is inserted between the two semi-circular halves of the cage and thereby brings the cage back to a proper diameter, but this is undesirable in practice.
In essence the invention provides a method of splitting a ring, such as a cage for a bearing such as a roller or ball bearing, in such a way that there are provided projections and recesses in the facing surfaces, whereby the two halves of the split ring may be reassembled in opposite orientation so that the projections on the facing surfaces of the two halves of the ring engage with one another to space the two halves of the ring apart, to restore the ring to a circular ring shape despite some of the material of the ring having been removed in the splitting process.
Preferably the splitting process is carried out on diametrically opposite sides of the ring.
Preferably the splitting process is carried out on each of the opposite sides of the ring simultaneously.
Preferably the splitting process is carried out on opposite sides of the ring in such a way as to provide an identical cut pattern on the facing surfaces of the two halves of the ring.
The ring may have a first edge and a second opposite edge, and engaging projections are provided on opposite sides of a circumferential line central between the first and second edges. The projections on each side of the central circumferential line may be provided in pairs which are equidistant from the central circumferential line.
The reassembling process in opposite orientation is carried out by rotating one half of the split ring through 180° about an axis at right-angles to the axis of the ring and at right-angles to a line between the cuts in the ring.
A preferred embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which:
As set out above, particularly where a bearing mounts a shaft which by virtue of its size or weight or position is relatively difficult to remove it is common to provide a split bearing assembly whereby one can remove the upper half of the bearing components for servicing or replacing parts of the bearing.
It is necessary for the cage 14 to be split about a plane passing through the axis A-A of rotation to the shaft.
We will now refer to the cage 14. It is clear that the cage 14 must be exactly circular and thus the two halves of the cage provided when it is split must be semicircular. Whilst in some circumstances the cage 14 may be moulded into two halves, for accuracy it is preferred to manufacture the cage 14 as a ring. In normal manufacture, the cage will be machined from a solid ring and then cut in half. Usually, if a cage is made from a solid ring and then cut in half, the joints of the cage between the two halves of the cages must somehow be packed or held apart to compensate for the material removed or else there must be some subsequent machining to true-up certain features of the cage. Alternatively, the cage may be made from two parts from the outset, but this requires careful machining in order that the two halves are properly matched.
The cage has a first edge 27 and an opposite second edge 28, a central circumferential (dashed) line 29 being shown equidistant from the two edges 27, 28.
The cage is manufactured usually of brass or bronze or other metal metallic material and once manufactured at this stage, has to be split into two halves.
The cage 14 is to be split generally in a plane including the axis B-B shown in
We now refer to
Various methods may be used to split the cage 14 into two halves (referred to as the lower half 14L and the upper half 14U in this case) but which ever method is used some metal is removed. We will describe the present invention in relation to splitting the cage.
The cage 14 is cut into two semicircular parts 14L and 14U by means of electrical discharge machining (EDM), sometimes referred to as spark erosion. This is carried out by means of a wire which is passed through the cage and a series of rapidly recurring current discharges is provided which erodes the material of the cage 14. The wire is in the form of a straight length which is parallel to the axis B-B in
The width 26 of the cut line 24 depends upon the diameter of the wire and the voltage and other factors but will generally be the same throughout the length of the cut, and of a known and predictable width ‘w’.
We now refer to
As the wire passes across and through each radially opposite side of the cage, it will be noted that the wire passes through the struts 22. The path 24 is generally linear in the plane A-A but is displaced up and down with respect to the plane as it passes through the cage to produce a series of projections and recesses. In this case we will refer to the projections as those parts formed by the wire EDM process which extend into the surface of the opposite half. The projections have been numbered 31-35 for the lower half 14L and 37-43 for the upper half 14U.
It will be noted that throughout most of their widths (as viewed in
As can been seen, the width ‘w’ of the cut line 24 is shown in
Once the cage 14 has been split as shown in
This is the situation shown in
It will be understand that because of the depth of each projection, the two halves of the cage are held apart by exactly the amount to compensate for the metal removed in the splitting process. Furthermore, because there are a number of projections across the width (in
To further align the two cage halves after cutting, tenons and recess are provided at 37 and 43.
Thus, in more detail referring to
The final step to assemble the cage is shown in
After manufacture and when the cage is assembled with clips, each half of the cage is marked near one joint so as to ensure correct pairing and orientation of the cage halves when they are subsequently dissembled for servicing.
The invention is not restricted to the details of the foregoing
For example, we have described a taper roller bearing arrangement with two rows of rollers.
In some circumstances a single row of rollers may be used with the cage comprising only two rings 17, 18 without the intervening ring 19 and as already referred to the bearing roller elements may be balls rather than rollers.
Rather than using clips 25, the two halves of the cage can be held together by fixings such as screws, bolts or rings.
Number | Date | Country | Kind |
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0917068.9 | Sep 2009 | GB | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/GB2010/051579 | 9/21/2010 | WO | 00 | 3/8/2012 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2011/039526 | 4/7/2011 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
543262 | Mossberg | Jul 1895 | A |
3199935 | Pitner | Aug 1965 | A |
3251118 | Pitner | May 1966 | A |
3431037 | Benson | Mar 1969 | A |
3494684 | Benson | Feb 1970 | A |
T102401 | Toth | Nov 1982 | I4 |
4475777 | Hofmann et al. | Oct 1984 | A |
5184899 | Harimoto | Feb 1993 | A |
5261159 | Yasuda et al. | Nov 1993 | A |
5630669 | Stewart | May 1997 | A |
6666584 | Yokota | Dec 2003 | B2 |
6692156 | Ohura et al. | Feb 2004 | B1 |
6981801 | Yokota | Jan 2006 | B2 |
7258492 | Yoon | Aug 2007 | B2 |
7270484 | Waseda | Sep 2007 | B2 |
7866891 | Waseda et al. | Jan 2011 | B2 |
8057105 | Earthrowl et al. | Nov 2011 | B2 |
8136998 | Murata et al. | Mar 2012 | B2 |
20070116393 | Oishi et al. | May 2007 | A1 |
20120211470 | Webster et al. | Aug 2012 | A1 |
Number | Date | Country |
---|---|---|
8008271 | Jun 1980 | DE |
195 19 798 | Dec 1995 | DE |
961203 | Jun 1964 | GB |
H05-89952 | Dec 1993 | JP |
2000240660 | Sep 2000 | JP |
WO 2013175922 | Nov 2013 | WO |
Entry |
---|
International Search Report of International Application No. PCT/GB2010/051579 dated Nov. 26, 2010. |
Written Opinion of International Application No. PCT/GB2010/051579 dated Nov. 26, 2010. |
Number | Date | Country | |
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20120211470 A1 | Aug 2012 | US |