GB2388166A

GB2388166A - A rolling bearing assembly with load control recesses

Info

Publication number: GB2388166A
Application number: GB0304888A
Authority: GB
Inventors: Brian Edward Earthrowl; Martin Janek Caspall
Original assignee: Cooper Roller Bearings Co Ltd
Current assignee: Cooper Roller Bearings Co Ltd
Priority date: 2002-03-05
Filing date: 2003-03-04
Publication date: 2003-11-05
Also published as: GB0304888D0; KR20030074231A; DE10309829A1; GB0205150D0

Abstract

A bearing assembly for supporting a roll of a casting machine is composed of a split roller bearing (fig 2, 19) with rollers (20) guided for movement around an outwardly facing track defined by a split inner ring (21) and an inwardly facing track defined by a two-part housing (31, 24). The housing has a primary component (31) which maybe supported on a base plate (fig 79, 41) a roll stand. This primary component (31) is relieved as with recesses (32) in the base surface and by this measure the component (31) is allowed to flex and deform during use to control the load distribution. A number of recesses 32 may be present and they may preferably be seperated by a projection or tenon 40 that may or may not extend outwardly beyond the base supportive surface 26.

Description

A hearing assembly usable for supoortin2 a roll of a casting machine and a

method of controUiny the loading thereof The present invention relates in general to steel casting processes and machines and more particularly to bearing assemblies for supporting the rolls of steel casting machines.

A typical casting machine as well as roll units and bearing assemblies therefor win be described hereinafter with reference to Figures I and 2 ofthe accompanying drawings.

An object of the invention is to provide an improved form of roll bearing assembly and a method of better controlling the loads thereon in continuous casting of steel slabs.

In one aspect the invention provides a split roper bearing assembly for use in supporting rods in steel casting machines, said assembly comprising a split inner ring defining an outer track for a set of rollers and a housing composed of a primary component and a secondary component detachably Eked to the primary component, the primary housing component defining an inner track for the ropers, wherein the primary component is relieved internally or externally to an extent to permit flexure ofthe primary housing component during operation for load control.

In one embodiment of the invention the primary housing component has a main supportive surface which is sub-divided by at least one recess acting at the relief which is designed not for location but for load control.

The load control recess or other relief measure is designed so that during use and when the assembly experiences peak loads the primary housing component can deform elastically.

Instead of providing a recess or other relief directly in the exterior supportive surface of the primary housing component an interior slot or gap can be provided in the body of the housing component. Such a slot can be created by machining. In another construction however the primary housing component is itself split into two sub components: a base block and a sandwich plate. The latter then forms the main supportive surface usually by resting on a base of a roll stand. A space can then be established between the base block and the sandwich plate to act as the load control relief.

In another aspect the invention provides a method of controlling loading of rollers in a split roller bearing assembly supporting a roll of a steel casting machine said method comprising creating an internal or external relief in a primary housing component defsung a track for the rollers of the assembly and adapted to be supported on a base plate of a roll stand, the relief allowing the pnrnay housing component to flex and deform resiliently to control the load distribution to the rollers. The invention also provides such a method of control by creating separate planar support surfaces on a primary housing component of the assembly defining a track for the rollers of the assembly and allowing the primary component to deform resiliently to create a co-planar surface extended support on the component including the separate support surfaces before the maximum of a peak load occurs whereby to control the load distribution imparted to the rollers. The separate planar surfaces can he created by the presence of a load control recess or shallow depression in an

otherwise continuous planar support surface and the resultant extended support surface also includes an innermost surface of the recess or depression.

A number of different arrangements can be adopted depending on the means provided for location of the primary component with its base surface on a roll stand base. For example, a central location tenon may project beyond the base supportive surface of the primary component and in this case load control recesses or other reliefs may be located at either side of the tenon.

The base support surface is then defined by two surfaces each extending between an outer flank of one of the recesses and a side wall of the primary component. In this construction, the location tenon fits into a recess or aperture in a roll stand base plate. In a modified arrangement the tenon does not project beyond the base supportive surface but has an outer surface which forms part of this surface. In this case the roll stand base plate can have upstanding walls or ribs which locate on the sides of the primary component. The central projection or tenon can be replaced by a shallow central location recess which in the inverse manner receives an upstanding projection on the roll stand base plate. Narrow ribs which define part of the base support surface then extend between the load control recesses and the central location recess.

Threaded holes can be provided in the separate planar surfaces of the support surface to receive bolts used to secure and clamp the complete housing to a roll stand base in known manner.

The invention may be understood more readily and various other aspects and features of the invention may become apparent from consideration of the following description.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein: Figure I is a schematic view of part of a typical casting machine; Figure 2 depicts one of the roll units of the casting machine as well as a known form of roller bearing assembly for rotatably supporting the central roll of the roll unit; Figure 3 is a front view of a roller bearing assembly constructed in accordance with the invention; Figure 4 is a view from the underside of the assembly shown in Figure 3; Figure 5 is a plan view of the assembly shown in Figure 3; Figure 6 is a diagrammatic part-sectional side view of the assembly shown in Figure 3; Figures 7a to 7c are diagrammatic representations of alternative forms of the base region of the assembly shown in Figures 3 to 6; Figure 8 is a front view of another roller bearing assembly constructed in accordance with the invention; Figure 9 is an end view of the assembly shown in Figure 8;

Figure I O is a front view of a further roller bearing assembly constructed in accordance with the invention and Figure 11 is a front view of a further roller bearing assembly constructed in accordance with the invention. Figure I shows part of a known machine 4 for continuously casting steel slab. The machine employs sets of roll units IO arranged in parallel and supported by roll stands 9. Each roll unit 10 is composed of a central roll axially spaced apart Dom two end rolls. The construction of one of the roll units 10 is shown in Figure 2 where the central roll is designated I I and the end rolls are designated 12, 13. Each roll unit 10 is at least 3 metres long and the roll units 10 in each set are spaced apart by about 30 cm ("S" in Figure 1). The rolls 10, 12, 13 serve collectively to compress, shape and guide molten steel introduced vertically into a rectangular slot 15.

As can be seen in Figure 1, the molten steel introduced into the slot 15 passes between sets of roll units I O initially disposed in a vertical path V and then progressively passes through farther roll units 10 in a smooth curved path C to enter a horizontal path H. As the molten steel enters the slot 15 as an extrusion it passes through the slot 15 and is sprayed with water by nozzles (not shown) to form an external skin which envelopes the molten steel core. The gap between the corresponding individual rolls I I, 12, 13 of the sets of roll units I O is progressively made smaller so the molten steel is gradually formed into the required thickness of the finished slab product.

The slab tends to solidify over the horizontal path H of the machine and the continuous slab is finally cut into lengths before further processing.

Turning now back to Figure 2, the axes of the rolls I 1, 12, 13 should be aligned and straight and separate spindles are used to support the rolls 11, 12, 13. The spindles are rotatably mounted on bearing assemblies 16, 17 at the ends and by central bearing assemblies 18 one of which is shown removed from the roll unit 10 and in an exploded representation.

As shown in Figure 2, the bearing assembly 18 is composed of a split roller bearing 19 with rollers 20 running around an outwardly facing track 22 formed by a split inner ring 21. A complementary inwardly facing track is formed on the inner surfaces of primary and secondary housing components 24, 25. The housing components 24, 25 are fixed together with bolts 8. The prirrary housing component 25 is supported by its continuous lower base surface 26 in the associated roll stand and in this conventional design there is a substantially planar continuous contact between the support surface 26 and the roll stand.

The bearing assemblies 16, 17, 18 are all subjected to harsh operating conditions during operation of the machine and this is particularly the case with the central bearir,g assemblies 18. In a typical application the bearing assembly 18 is subjected to heavy dynamic loads as the roll 11 compresses and guides the slab and the assembly 18 can be subjected to temperatures of around 1000 C. It is therefore necessary to cool the bearing assemblies 16, 17, 18 and this is achieved by circulating coolant through the primary housing component 25. It is also necessary to provide

lubrication for the rollers 20 and again this is achieved by circulating or introducing lubricant into the primary housing component 25 and thence into the interior of the bearing 19.

Another requirement of the casting machine is the ability to stop and start the casting process.

The process is usually started by introducing a solid bar, a so-called "dummy bar", into the slot 15 to hold back the molten steel as it is extruded. The passage of the more rigid solid bar causes high loads on the bearing assemblies 16, 17, 18 particularly over the vertical and curved path sections V and C. From time to time the flow of molten steel for the casting process may be interrupted and again as the slab solidifies it has to be removed before the new cast can be introduced. These processes cause peak loads to be imparted to the bearing assemblies 16, 17, 18. Figures 3 to 6 depict a modified form of bearing assembly designated 30 constructed in accordance with the invention which is especially designed to accommodate the peak loads. The assembly 30 is essentially as shown in Figure 2 and as described above except for the primary housing component now designated 31. Other reference numerals used throughout in common with Figure 2 denote like parts or features. As shown in Figures 3 to 6 the base support 26 of the primary component 31 is sub-divided by distinct rectangular recesses 32 to form two outer co-

planar surfaces 33, 34 of equal area. The recesses 32 has curved fillets between their flank walls and the innermost base surface 38. Between the recesses 32 there is a projection or tenon 40 extending outwardly beyond the surfaces 33, 34. The reference numerals 35, 36 are used to designate passages for coolant and lubricant respectively. The reference numeral 37 is used to

designate tapped bores for receiving bolts for securing the housing components 24, 31 to a base plate of the roll stand.

Figure 7b depicts the inter-engagement between the base support 26 of the housing 31 shown in Figures 3 to 6 with a base plate 41 of a roll stand. As can be seen the tenon 40 fits into an aperture 42 in the base plate 41 to locate the housing 31 and hence the assembly 30 in its operating position. The surfaces 33, 34 rest on the upper surface 43 of the base plate 41.

Figure 7a depicts a modified construction where the tenon 40 is formed on the base plate 41 and a further complementary location recess 44 is provided in the base support 26 of the housing 31.

Ribs 45 extend between the load control recesses 32 and the location recess 44.

Figure 7c shows a further modified construction where the tenon 40 does not project beyond the surfaces 33, 34 but has its lower surface coplanar therewith. In this construction the base plate 41 has upstanding ribs 46 which engage on the side of the housing 31 to locate the assembly 30.

In Figures 7a, 7b and 7c there is a small horizontal gap between the tenon 40 and the associated aperture typically between 0.1 and 0.3 mm which tends to close when the assembly experiences peak loads.

It has been demonstrated that when the bearing assembly 30 is used in a casting machine and experiences peak loads the primary component 31 tends to deform elastically to change the loading on the rollers 20. The recesses 32 are shaped and has dimensions such that with less than

peak loading the deformation of the component 31 is such that the load distribution on the individual rollers 20 is modified by sharing the load more evenly among the rollers such that the load on the highest roller is reduced by about 30%.

Nevertheless it has been found that there is a critical position for the rollers 20 at either side of a vertical centre line V (Figure 5) where the load is not affected by the Sexing of the housing component 31. When the rollers 20 at either side ofthe centre line V experience the highest load no improvement in load capacity can be achieved once the centre of the track defined by the housing component 31 has deflected by about 0.1 mm. Figure 8 depicts an embodiment in which the underside of the housing component 31 forming the base surface 26 is relieved with a shallow undercut or recess 32 about 0.1 mm in depth at either side of the tenon 40. Figure 9 shows that there are additional grooves 47 in the base surface 26 running parallel to the axes of the rollers 20. These grooves 47 receive suitable seals to prevent scale or other contaminants passing into the recesses 32 and obstructing the Sexure of the housing component The use of such seals ran also be adopted in the other illustrated embodiments of the invention.

There are numerous variations of the design of the housing component 31 to suit particular applications which may also influence the method of load control. One particular parameter which is of importance is the area of the base surface 26 in relation to the centre line V. Where the area is relatively large the volume of material in the lower region of the housing component 31 tends to increase the stiffness and reduces the elastic deflection of the housing component 31 below that needed to maximize the load bearing capacity. In the embodiment depicted in Figure 10 the primary housing component 31 is subdivided into an upper base block 48 and a lower

sandwich plate 49. The separate sandwich plate 49 now defines the housing base surface 26 with the tenon 40 but this surface is not relieved as in the other embodiments. Instead the lower surface of the base block 48 has a recess 50 and the upper surface of the sandwich plate 49 has a complementary projection Sl. There is a space 52 between the projection and recess SO, 51 which permit the necessary deflection and flexure of the base block 48 rather than the whole housing component 31 in the previous embodiments. The reference numerals 53 denote the abutting regions of the lower surface of the base block 48 and the sandwich plate 49.

It is not however necessary to create a two-part housing component 31 as in Figure 10. Instead a relief slot 54 can be machined in the housing component 31 as by wire erosion.

In all the embodiments there is a deliberate relief of the housing component 31 whether by recess or undercuts in the base or by spaces, gaps or slots within the body of the component 31 designed to provide the flexure necessary to improve the load capacity.

Claims

1. A split roller bearing assembly for use in supporting rolls in steel casting machines, said assembly comprising a split inner ring defining an outer track for a set of rollers and a housing composed of a primary component and a secondary component detachably fixed to the primary component, the primary housing component defining an inner track for the rollers; wherein the primary component is relieved internally or externally to an extent to permit flexure of the primary housing component during operation for load control.

2. A bearing assembly according to claim 1, wherein the primary housing component has a main base supportive surface which is sub-divided by at least one recess acting as the relief and designed for load control and not for location purposes.

A bearing assembly according to claim I or 2, wherein there are several load control recesses.

4. A bearing assembly according to claim 3, wherein the load control recesses are separated by a projection or tenon extending outwardly beyond the base supportive surface which is locatable in an aperture in a base plate of a roll stand to locate the assembly.

5. A bearing assembly according to claim 2, wherein the load control recesses are separated by a central portion which has an outer surface forming part of the base supportive surface.

6. A bearing assembly according to claim 5, wherein the base supportive surface is adapted to rest on a planar upper surface of a base plate of a roll stand and side ribs on the base plate engage with the sides of the primary component to locate the assembly.

7. A bearing assembly according to claim 2, wherein the load control recesses are separated from another central recess by ribs and the other recess is adapted to receive an upstanding projection on a base plate of a roll stand to locate the assembly.

8. A bearing assembly according to any one or more of claims 2 to 7, wherein the or each load control recess is of generally rectangular profile in cross-section.

9. A bearing assembly according to claim 8, wherein the or each recess has parallel flank walls and curved margins joining the flank wall to the innermost surface.

10. A bearing assembly according to any one or more of claims 2 to 9, wherein the main supportive surface possesses threaded holes for receiving bolts used to secure the primary housing component to a base plate of a roll stand.

11. A bearing assembly according to claim 1, wherein the relief is a slot machined within the body of the primary housing component.

12. A bearing assembly according to claim 1, wherein the primary housing component is subdivided into a base block and a sandwich plate dcEining a supportive surface for the housing

component and a space or gap acting as the relief is established between the base block and the sandwich plate.

13. A bearing assembly according to claim 12, wherein the base block and the sandwich plate have an interengaging projection and recess and the space or gap is established between the projection and the recess.

14. A bearing assembly according to any one or more of claims 2 to 10 or claim 12 or 13, wherein the main supportive surface is at least partly sealed to prevent the ingress of contaminants into the recess, space or gap.

15. A bearing assembly substantially as described with reference to, and as illustrated in Figures 3 to I 1 of the accompanying drawings.

16. A method of controlling loading of rollers in a split roller bearing assembly supporting a roll of a steel casting machine; said method comprising creating an internal or external relief in a primary housing component defining a track for the rollers of the assembly and adapted to be supported on a base plate of a roll stand, the relief allowing the primary housing component to flex and deform resiliently to control the load distribution to the rollers.

17. A method of controlling loading of rollers in a split roller bearing assembly substantially as herein described.