ADJUSTABLE LOCKING CAM ASSEMBLY

Abstract: An adjustable locking cam assembly (10) for locking roller bearings (16) at both ends of a roll shaft (12) of a roll (14) of the kind employed in mill stands used in steel rolling mills. The locking cam assembly (10) comprises a sleeve member (26) provided with a helical cam surface (28) standing out perpendicularly from the outer circumferential surface (30) of the sleeve member (26). The locking cam assembly (10) further comprises an adjustable locking member (60) rotabably received on the outer circumferential surface (30) of the sleeve member (26), and provided with a matching helical cam surface (62) that slibably engages with the helical cam surface (28) of the sleeve member (26) to cause axial movement of the adjustable locking member (60) towards a locked position. In the locked position the adjustable locking member (60) thrusts against the roller bearing (16) through a ball bearing (20), a spacer (24) and seal running ring (22). The adjustable locking member (60) comprises two halves which are held together by two bolts received in bores (68). The two bolts also enable the locking member (60) to be locked in the locked position to lock the roller bearing (16) on the shaft (12). The adjustable locking cam assembly (10) facilitates more efficient and rapid change over of the bearings (16) of one pair of rolls to the next pair.

Description: ADJUSTABLE LOCKING CAM ASSEMBLY FIELD OF THE INVENTION The present invention relates to an adjustable locking cam assembly for locking a bearing or similar structure on a shaft and relates particularly, but not exclusively, to such an assembly for locking roller bearings on a roll shaft of the kind used in mill stands in the steel industry. DISCUSSION OF PRIOR ART Recently several mill stands rom one of our merchant mills were converted to use roller bearings on the rolls instead of the original fabric and wood bearings. These bearings were provided with stainless steel roller bearing adjusting lock nuts for retaining the bearings at both ends of the roll shaft. The roll shaft is typically provided with an annular channel at both ends, in which the two halves of a split ring are received to form a circular ring provided with an external screw-thread on its outer circumferential surface. One half of the split ring is provided with a key-way on its inner circumference, that aligns with a matching key-way provided in the channel on the shaft. A relatively small key fits into the aligned key-ways to prevent rotation of the split ring in the channel. The two halves of the split ring are held together by a ring-shaped adjusting nut, provided with an internal screw-thread that engages with the external screw-thread of the split ring. When the adjusting nut is received onto the external screw-thread of the split ring, it can be screwed on tightly against one or more spacer rings, located between it and the roller bearing, to a locked position, where it prevents axial movement of the roller bearing on the roll shaft. Both the split ring and the adjusting nut are made from like material, namely stainless steel. The disadvantages of these adjusting lock nuts become apparent when changing the bearings from one pair of rolls to the next pair. Firstly, the threads on the adjusting nut and the two halves of the split ring are easily damaged, causing setting-up delays. Secondly, it is very difficult to hold the two halves of the split ring together and to get the external threads to align correctly, to even start screwing on the nut. Thirdly, if the split ring is not perfectly round and true, or there is a gap when the two halves are assembled together, one half tends to rotate when the nut is screwed on. This effectively turns the adjusting nut into a lock nut that is very difficult to tighten all the way up, and also makes it practically impossible to feel the adjustment on the bearing thrust. All of these problems make change over of the bearings extremely difficult and time consuming. Often it takes up to four hours to change the bearings from one pair of rolls to another pair. A further problem is that during service the threads become worn and/or stretched, which allows the nut to work loose, eventually undoing itself by shearing the 6mm diameter cap-head socket screws that go through the nut into a seal running ring. When the nut comes undone, the bearing can float, and water, mill scale, etc. can enter the bearing and cause premature failure of the expensive roller and ball¬ bearings. SUMMARY OF THE INVENTION The present invention was developed with a view of overcoming one or more of the above problems with the existing roller bearing adjusting lock nuts, and to provide an adjustable locking cam assembly that would facilitate more efficient change over of the bearings from one pair of rolls to the next pair. Although the invention was developed specifically with this application in view, it became apparent that the adjustable locking cam assembly would have wider application in other similar situations where bearings need to be adjusted for thrust, or for locking roll sleeves and the like to mandrils. According to the present invention there is provided an adjustable locking cam assembly for locking a bearing or similar structure on a shaft, the assembly comprising: a sleeve member adapted to be received on the shaft and to engage with the shaft so as to prevent axial movement of the assembly relative to the shaft in its locked position, said sleeve member being provided with a cam surface on an outer circumferential surface of the sleeve member; and, an adjustable locking member adapted to be rotatably received on said outer surface of the sleeve member and having a cam surface provided on an end face of the adjustable locking member whereby, in use, when said adjustable locking member is received on the sleeve member and rotated, said cam surface slidably engages with the cam surface on the sleeve member, to cause axial movement of the adjustable locking member towards a locked position, in which the adjustable locking member thrusts against the bearing or similar structure on the shaft. Preferably said cam surface on the sleeve member is a helical cam surface, and the cam surface on the adjustable locking member is preferably a matching helical cam surface. Preferably said sleeve member comprises first and second halves of semi-circular shape, wherein the two halves are held together by said adjustable locking member in the form of a hollow cylinder, when the assembly is in its assembled condition. In the preferred embodiment of the assembly said sleeve member is provided with an annular portion projecting radially inwardly, said annular portion being adapted to engage with an annular channel provided in the shaft so as to prevent axial movement of the assembly relative to the shaft in its locked position. Preferably said adjustable locking member also comprises first and second halves of semi-circular shape, wherein the two halves are held together by fastening means to form a circular ring, when the assembly is in its assembled condition. Preferably said fastening means is adjustable fastening means whereby, in use, the fastening means can be loosened to allow the adjustable locking member to rotate on the outer surface of the sleeve member, and whereby the fastening means can be tightened when the ring member thrusts against the roller bearing or similar structure to lock the assembly in its locked position. The helical cam surface on the sleeve member and the matching cam surface on the adjustable locking member are preferably each provided in two sections, a respective first section on the first halves of the sleeve member and the adjustable locking member respectively, and a respective second section on the second halves of the sleeve member and adjustable locking member respectively. BRIEF DESCRIPTION OF DRAWINGS In order that the nature of the invention may be more clearly ascertained a preferred embodiment of the adjustable locking cam assembly will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates one end of a roll shaft showing a roller bearing and a preferred embodiment of the locking cam assembly in section view; Figures 2(a), (b) and (c) illustrate a sleeve member in the preferred embodiment of Figure 1; Figures 3(a) and (b) illustrate a key member in the preferred embodiment; Figures 4(a), (b) and (c) illustrate an adjustable locking member in the preferred embodiment; Figures 5(a) and (b) illustrate a seal running ring in the preferred embodiment; and Figures 6(a) and (b) illustrate a spacer ring in the preferred embodiment of Figure 1. DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Figure 1 illustrates a preferred embodiment of the adjustable locking cam assembly 10 fitted on a roll shaft 12 of a roll 14 of the kind employed in mill stands used in steel rolling mills. The roll 14 is rotatably supported at both ends in a mill stand on two roller bearings similar to roller bearing 16. On one side of roller bearing 16 is a fixed roll spacer 18, and on the other side immediately adjacent is a ball-bearing 20. Between the locking cam assembly 10 and ball¬ bearing 20 there is provided a seal running ring 22, as in the prior art arrangement, and a spacer 24 through which any thrust from assembly 10 can be transferred to the bearings 16 and 20. The shape and configuration of the seal running ring 22 and spacer 24 can be seen more clearly in Figures 5 and 6 respectively. The adjustable locking cam assembly 10 comprises a sleeve member 26 adapted to be received on the roll shaft 12 and to engage with the roll shaft so as to prevent axial movement of the assembly 10 relative to the shaft 12 in its locked position. The sleeve member 26 is provided with a helical cam surface 28 standing out substantially perpendicularly from the outer circumferential surface 30 of the sleeve member 26. Sleeve member 26 is further provided with an annular portion 32 projecting radially inwardly and being adapted to engage with an annular channel 34 provided in the shaft 12 the annular channel 34 prevents axial movement of the assembly 10, relative to the shaft 12, when the assembly is in its locked position (as illustrated in Figure 1) , since the projecting portion 32 engages with one side wall of the channel 34. Rotation of the sleeve member 26 on shaft 12 is prevented by a key 36 which is received in a key-way 38 cut out of the projecting portion 32 of the sleeve member. A matching key-way 40 is provided in the opposite side wall of the channel 34. When the key-ways 38 and 40 are aligned and key 36 inserted therein, sleeve member 26 is prevented from rotating relative to the shaft 12. Key 36 is preferably provided in two pieces, and the second piece 42 protrudes outwardly from the outer circumferential surface of shaft 12 to engage in another key-way 44 provided in the seal running ring 22. Keys 36 and 42 are illustrated in Figures 3(a) and (b) respectively. The configuration of sleeve member 26 can be more clearly seen in Figures 2(a), (b) and (c) . Referring to Figure 2(a) the sleeve member 26 comprising first and second halves 46 and 48 respectively, is illustrated in end view. Key-way 38 in the first half 46 of sleeve member 26 can be clearly seen in Figure 2(a) . The two halves of sleeve member 26 are semi-circular in shape and are produced by splitting the ring member 26 on a band-saw through the line V-V after final machining as shown. Material removed by sewing is replaced with welding so that both halves 46 and 48 when clamped together form a perfect hollow circular cylinder. The inner circumferential surface 50 of annular projecting portion 32 is machined to be received in the annular channel 34 in the roll shaft 12. Cut-out portions 52 are merely provided to simplify the assembly of the two halves of sleeve member 26 on the roll shaft 12. Figure 2(b) is a section view of the two halves 46 and 48 of the sleeve member taken through the line W-W in Figure 2(a) . In Figure 2(b) it can be seen how the helical cam surface 28 of the sleeve member is provided in two sections, a first section on the first half 46 of the sleeve member and a second section on the second half 48 of sleeve member. Each section of the helical cam surface 28 rises 10mm from its lowest to its highest point through 180°. The profile of helical cam surface 28 can also be clearly seen in Figure 2(c) which is a view taken through the line V-V in Figure 2(a) . In Figure 1 it can be seen that the adjustable locking cam assembly 10 further comprises an adjustable locking member 60 adapted to be rotatably received on the outer circumferential surface 30 of the sleeve member 26. Adjustable locking member 60 is provided with a matching helical cam surface 62 on one end face thereof whereby, in use, when the adjustable locking member 60 is received on the sleeve member 26 and rotated, the matching helical cam surface 62 slidably engages with the helical cam surface 28 of the sleeve member to cause axial movement of the adjustable locking member 60 towards a locked position. In the locked position the adjustable locking member 60 thrusts against the ball bearing 20 through spacer 24 and seal running ring 22. When the preferred embodiment of the adjustable locking cam assembly 10 illustrated in Figure 1 is viewed end-on from the right hand side of Figure 1, rotation of the adjustable locking member 60 in a clockwise direction causes axial movement of the adjustable locking member towards the locked position, whereas rotation in the anti-clockwise direction releases the adjustable locking member from the locked position. Adjustable locking member 60 also preferably comprises first and second halves 64 and 66 respectively of semi-circular shape, as can be seen more clearly in Figure 4(a). The two halves 64 and 66 of the adjustable locking member 60 are held together by fastening means (not illustrated) to form a circular ring, when the assembly 10 is in its assembled condition. Two fastening means are preferably provided in the form of two socket head cap screws or bolts received in bores 68 extending tangentially through the two halves of the adjustable locking member 60. The bores 68 are provided in an annular portion 70 which projects from the outer circumferential surface of the adjustable locking member 60 as can be seen most clearly in Figures 4(b) and (c) . Figure 4(b) is a side view of the second half 66 of the adjustable locking member 60 viewed along the line Y-Y in Figure 4(a). The profile of the matching helical cam surface 62 on the end face of the adjustable locking member half 66 is clearly visible in Figure 4(b). As with the cam surface provided on the sleeve member 26, the matching cam surface 62 provided on adjustable locking member half 66 rises 10mm through 180°. Matching helical cam surface 62 is also provided in two sections on the respective halves 64 and 66 of the adjustable locking member 60 as can be seen more clearly in Figure 4(c) . Figure 4(c) is a section view of the two halves of the adjustable locking member 60 taken through the line X-X in Figure 4(a). Unlike the sleeve member 26, the two halves 64 and 66 of the adjustable locking member 60 are provided with a 3mm gap therebetween when the two halves are placed together in the form of a circular ring. In Figure 4(c) the aligned bores 68 in the respective halves 64 and 66 of the adjustable locking member can be seen in broken outline. The bore 68 provided in the first half 64 of the adjustable locking member is threaded to receive the socket head cap screw or bolt in screw-threaded engagement whereby, in use, the screw or bolt can be loosened or tightened to lock the adjustable locking member 60 onto the outer circumferential surface 30 of the sleeve member 26 when the adjustable locking cam assembly 10 is in its assembled condition. The 3mm gap enables the two halves 64 and 66 of the adjustable locking member 60 to be locked tightly to the outer circumferential surface 30 of the sleeve member 26 when the screws in bores 68 are .tightened. The screws received in bores 68 therefore perform three functions, namely holding the first and second halves of the adjustable locking member 60 together and, when the adjustable locking member 60 is received on the outer circumferential surface 30 of the sleeve member 26, they also hold the two halves 46 and 48 of the sleeve member together. When tightened the screws lock the two halves 64 and 66 of the adjustable locking member 60 onto the outer circumferential surface of the sleeve member whereby the adjustable locking member 60 cannot be rotated relative to the sleeve member 26. Cut-out portions 72 in the annular projecting portion 70 of the locking member 60 are provided to facilitate rotation of the locking member 60 relative to the sleeve member 26 when the fastening means are loosened. The process of removing the bearings from the roll shaft 12 will now be described with reference to Figure 1. In Figure 1 the adjustable locking cam assembly 10 is illustrated in its locked position wherein the adjustable locking member 60 has been rotated to thrust against the spacer ring 24 through the lifting action provided by the sliding engagement of the respective cam surfaces. The assembly has been locked in position by tightening the fastening means received in bores 68 of the locking member 60. The first step in removing the bearings 16 and 20 from the roll shaft 12 is to loosen the fastening means in bores 68 of the locking member 60 when the fastening means in bores 60 are loosened the locking member 60 can be rotated in the anti-clockwise direction on the outer circumferential surface 30 of the sleeve member 26, thus releasing the thrust on the bearings through spacer 24 and seal running ring 22. As the fastening means are released the two halves 64 and 66 of the locking member 60 may be separated, and immediately thereafter or simultaneously the two halves 46 and 48 of the sleeve member 26 can also be separated and removed from the roll shaft 12. Spacer 24 can then be slid off the roll shaft 12, and it is then a relatively simple operation to remove the keys 42 and 36 from their respective key-ways and to slide the seal running ring 22 over the roll shaft 12 in like manner. The roller bearing 16 and ball-bearing 20 may then be slid off the roll shaft 12 and changed over to another roll shaft as required. The process of replacing the bearings and the adjustable locking cam assembly 10 onto a roll shaft is simply the reverse of the above described operation. From the above description it will be apparent that the adjustable locking cam assembly according to the present invention greatly facilitates rapid change over of bearings from one roll shaft to another. Although the new adjustable locking cam assembly is more difficult to manufacture, and generally requires greater precision due to the limited amount of adjustment obtained from the cams compared with the old threaded system, it is much simpler to assemble and disassemble and cannot work off during use in the way the old threaded system could. With the new adjustable locking cam assembly it is possible for one person to change the bearings from one pair of rolls to the next pair (i.e. one at each end of the roll shaft) in one hour. Even an inexperienced person can achieve the change over:in less than an hour and a half because of the simplicity of the new adjustable locking cam assembly. From the above description of a preferred embodiment of the adjustable locking cam assembly, it will be apparent that the assembly according to this invention does facilitate more efficient change over of the bearings of one pair of rolls to the next pair. The adjustable locking cam assembly of the invention can have applications in other areas where bearings need to be adjusted for thrust, or for locking sleeves onto rolls or shafts. Furthermore, it will apparent to those skilled in the mechanical and other relevant technical fields, that numerous variations and modifications may be made to the described assembly, other than those already described, without departing from the basic inventive concepts. For example, it is not essential that the sleeve member and the adjustable locking member be provided in two halves, since either one or both of the members could be provided as a single component. In this alternative arrangement, other means for locking the sleeve member to the roll shaft and locking the adjustable locking member in its locked position could be readily devised. All such variations and modifications are to be considered to be within the scope of the invention, the nature of which is to be determined from the foregoing description and the appended claims.

Claims: THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. An adjustable locking cam assembly for locking a bearing or similar structure on a shaft, the assembly comprising: a sleeve member adapted to be received on the shaft and to engage with the shaft so as to prevent axial movement of the assembly relative to the shaft in its locked position, said sleeve member being provided with a cam surface on an outer circumferential surface of the sleeve member; and, an adjustable locking member adapted to be rotatably received on said outer surface of the sleeve member and having a cam surface provided on an end face of the adjustable locking member whereby, in use, when said adjustable locking member is received on the sleeve member and rotated, said cam surface slidably engages with the cam surface on the sleeve member, to cause axial movement of the adjustable locking member towards a locked position, in which the adjustable locking member thrusts against the bearing or similar structure on the shaft. 2. An assembly as defined in claim 1, wherein said cam surface on the sleeve member is a helical cam surface, and the cam surface on the adjustable locking member is a matching helical cam surface. 3. An assembly as defined in claim 2, wherein said sleeve member comprises first and second halves of semi¬ circular shape, wherein the two halves are held together by said adjustable locking member in the form of a hollow cylinder, when the assembly is in its assembled condition. 4. An assembly as defined in claim 3, wherein said sleeve member is provided with an annular portion projecting radially inwardly, said annular portion being adapted to engage with an annular channel provided in the shaft so as to prevent axial movement of the assembly relative to the shaft in its locked position. 5. An assembly as defined in claim 4, wherein said adjustable locking member also comprises first and second halves of semi-circular shape, wherein the two halves are held together by fastening means to form a circular ring, when the assembly is in its assembled condition. 6. An assembly as defined in claim 5, wherein said helical cam surface on the sleeve member and the matching helical cam surface on the adjustable locking member are each provided in two sections, a respective first section on the first halves of the sleeve member and the adjustable locking member respectively, and a respective second section on the second halves of the sleeve member and adjustable locking member respectively. 7. An assembly as defined in claim 5, wherein said fastening means adjustable fastening means whereby, in use, the fastening means can be loosened to allow the adjustable locking member to rotate on the outer surface of the sleeve member, and whereby the fastening means can be tightened when the ring member thrusts against the roller bearing or similar structure to lock the assembly in its locked position. 8. An assembly as defined in claim 4, wherein said annular portion in the sleeve member and said annular channel in the shaft are each provided with a key-way adapted to receive a key therein whereby, in use, when the respective key- ways are aligned said key can be inserted therein to prevent rotation of the sleeve member relative to the shaft. 9. An assembly as defined in claim 7, wherein said fastening means is in the form of two screw-threaded members received through a pair of respective bores extending tangentially through the two halves of the adjustable locking member at diametrically opposed locations.

Inventors: BUSHELL RONALD HENRY ALEXANDER, KLESSENS WILHELMUS JOHANUS MAR, BUSHELL, RONALD, HENRY, ALEXANDER, KLESSENS, WILHELMUS, JOHANUS, MARIA
Applicants: BROKEN HILL PTY CO LTD, THE BROKEN HILL PROPRIETARY COMPANY LIMITED
Application year: 1990
Main classification: F16C35
IPC codes: B21B31, F16C13, F16C35