GB2139126A - Rolling mill and work roll backup system therefor - Google Patents

Abstract

A rolling mill is disclosed in which the work roll (26) has a vertical backup roll (30) in substantially the same vertical plane as the work roll axis and a lateral backup system which transmits lateral force components to a substantially rigid frame (10). The lateral backup system includes a lateral backup roll (40, 41), a bearing roller (43, 44) and a mounting structure (46, 47) which rotatably supports the lateral backup roll (40, 41) in contact with the work roll (26) and the bearing roller (43, 44) outboard of and in contact with the lateral backup roll (40, 41), the mounting structure having a surface (54, 55) in contact with the frame (10). A support (48, 49) for the mounting structure is adjustable to permit the alignment of the central axes of the work roll (26), lateral backup roll (40, 41), bearing roller (43, 44) and the contact point with the frame (10). The surface (54, 55) in contact with the frame (10) is preferably curved. <IMAGE>

Description

SPECIFICATION Rolling mill and work backup system therefor This invention relates to a rolling mill which permits the use of small diameter work rolls with an improved technique for lateral back-up of such work rolls.

Those skilled in the rolling mill art are familiar with the basic types of rolling mills including those known as cluster mills as well as those known as "four high" rolling mills and the various arrangements and permutations thereof, typical examples of which are found in the following U.S. patents.

2,118,284 Worthington 2,139,872 Worthington 2,368,030 Larsson 2,479,974 Sendzimir et al 2,909,088 Volkhausen 3,128,650 Leufven 3,523,439 Leifeld et al 3,580,035 Bond et al 3,695,082 Leifeld et al 4,197,731 Verbickas et al 4,248,073 Verbickas et al 4,270,377 Verbickas et al 4,289,013 Hunke The basic four high mill has evolved into mills having various design features but some fundamental aspects remain somewhat the same. A pair of work rolls is mounted so as to engage a strip of metal, the available gap between the rolls being such that the thickness of the strip is decreased as the strip passes through the mill. The work rolls are usually small in diameter compared with other rolls in the mill because smaller rolls have a greater reducing effect on the strip.Also, the work rolls are normally journaled at each end in a loose fashion, i.e., their ends are guided in vertical slots rather than being mounted in fixed bearings.

The work rolls are restrained and limited in their vertical movement in various ways but a common arrangement is one in which the work rolls are contacted by intermediate backup rolls which are typically larger in diameter by a factor of 3 or more and which are often driven rolls, imparting rotary motion to the work rolls by friction. Still larger backup rolls can be used behind the intermediate rolls, thus forming a "six high" mill.

While these rolls are quite capable of vertically restraining the work rolls and, in conjunction with various roll bending and shaping systems, can give the work roll a desired shape to impart the strip, lateral forces must also be dealt with, i.e., forces to counter the lateral force components of the drive torque from the intermediate or backup roll. Thus, side support roll arrangements have been devised such as that shown by U.S. Patent 4,270,377 in which a side backup roll is provided on each side of the work roll (to permit bi-directional rolling of the strip) and each side backup roll is, in turn, restrained, vertically as well as laterally, by two bearing roller assemblies, each of which includes an axial array of relatively short rollers mounted on roller bearings on a shaft, the shaft itself being supported between the bearings by a fixed structure.

While this technique does, indeed, provide lateral support, it also has some undesirable features, one of which is a limitation on the diametral size of the two bearing roller assemblies due to the available vertical space between the intermediate roll and the strip being rolled.

Bearing roller assemblies and their supporting members are very difficult and expensive to manufacture. If the overall system requires the use of small diameter bearing assemblies, this means that either they must be more frequently replaced at great cost and long machine shut-down time, or else it requires that other expensive and complicated means must be employed to protect the roller bearing assemblies from damage. Because the load capacity of the small bearings is small, overloads in the rolling forces can be a common occurrence.

Other forms of lateral backup have similar shortcomings, leading to the development of complicated backup systems with large numbers of rolls and other complicated mechanical devices.

An object of the present invention is to provide a stronger lateral backup system capable of effectively countering the lateral force components which are developed in a mill without limiting in any meaningful way the variety of work roll sizes which can be used.

According to the present invention there is provided a lateral backup system for a work roll in a rolling mill of the type having a substantially rigid frame for supporting the rolls and at least one vertical backup roll having an axis of rotation in substantially the same plane as the work roll axis, the system comprising a lateral backup roll; a bearing roller assembly having a plurality of rollers axially spaced along a shaft; a substantially rigid mounting structure having a surface for contacting the frame and having means for rotatably supporting the lateral backup roll in contact with one side of said work roll and the rollers of the bearing roller assembly in contact with the lateral backup roll; means for supporting the mounting structure and means for adjusting the location of the mounting structure supporting means to align the centers of rotation of the work roll, the lateral backup roll and the bearing roller assembly to thereby resolve the resultant lateral forces into a line between the work roll axis and the frame.

Specific embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa side elevation of a typical rolling mill incorporating a backup system in accordance with the present invention; Figure 2 is a schematic diagram showing in enlarged side elevation the arrangement of rolls in the apparatus of Figure 1; Figure 3 is an enlarged partial side elevation of a portion of the apparatus of Figure 1 including the backup system of the invention; Figure 4 is an enlarged bottom plan view in partial section along line 4-4 of Figure 1; Figure 5 is an enlarged schematic side elevation of a backup system in accordance with the invention showing the adjustment capabilities thereof;; Figure 6 is a schematic diagram of a backup system in accordance with the invention illustrating the vector forces involved; Figure 7 is a partial sectional view, partially cut away, along line 7-7 of Figure 6; and Figures 8-11 are schematic side elevations of alternative roller arrangements usable with the system of the present invention.

Figure 1 shows a side elevation of a typical rolling mill incorporating the system in accordance with the invention. The majority of the mill illustrated in Figure 1 is conventional and the exact configuration is not particulalrly important to the invention. Thus, it will be described only in rather general terms, recognizing that the invention can be applied to mills of various other configurations.

The mill shown in Figure 1 includes a massive frame 10 having pedestal flanges 11 by which the mill can be supported. As viewed from the side, the frame has an elongated, generally rectangular opening 14 which receives upper and lower assemblies 16 and 18, one or both of which are vertically movable by hydraulic or other means indicated generally at 20 and 21 for the purpose of adjusting the various dimensional relationships to accommodate work rolls of various sizes and to work with strips of various initial thicknesses. Such an apparatus is shown in U.S. Patent 3,974,672, Herbst.

At the midpoint of the mill is gap 23 through which a strip of metal can be passed either from the left to the right or in the opposite direction, or alternatingly in both directions, between work rolls 25 and 26, the work rolls being pressed, shaped and restrained by a system of backup rolls which can be more clearly seen in the schematic diagram of Figure 2. As shown therein, a strip 28 is passing between work rolls 25 and 26 in the direction indicated by the arrow, the work rolls being vertically backed up by intermediate rolls 29 and 30 which have diameters significantly largerthan rolls 25 and 26. In turn, the intermediate rolls are vertically backed up by significantly larger backup rolls 32 and 33 which are supported in the roll assemblies 16 and 18 referred to in Figure 1.

As previously discussed, rolls 29, 30, 32 and 33 are quite adequate to provide the vertical restraint and pressure necessary to establish a dimensional gap between work rolls 25 and 26 so that the work rolls can accomplish the desired reduction of strip 28.

However, as the strip passes between rolls 25 and 26 considerable lateral force is exerted on the work rolls by frictional engagement with rolls 29 and 30 which are usually the power-driven rolls. As previously discussed, sets of two or more lateral backup rolls in contact with each work roll on each side thereof have been used for this purpose in the past, as well as other kinds of arrangements.

In accordance with the present invention, the lateral restraint for roll 25 is provided by backup rolls 34 and 35 on opposite sides of roll 25, and bearing roller sets 37 and 38 outboard of rolls 34 and 35, respectively, these being shown in Figures 4, 5 and 7. As is conventional in this field, the elongated rolls such as 25, 29,32,34 and 35 are symbolized in the schematic drawing by single circles while the bearing roller sets 37 and 38 are symbolized by double, concentric circles.

The lateral backup for work roll 26 is provided, in a similar fashion, by lateral backup rolls 40 and 41 on opposite sides of work roll 26 and bearing roller assemblies 43 and 44 outboard of rolls 40 and 41, respectively, as shown in Figure 3.

As is customary with the bearing roller assemblies, each assembly comprises an axially arranged, spaced set of rollers mounted on bearings and supported by a shaft which rests in a frame work having supports between each adjacent pair of bearing rollers. The objective of this arrangement is to transmit the forces from rolls 34, 35,40 and 41 through the rollers of the bearing roller assembly and through those bearings to the shaft, which, in turn, transmits the forces to the framework supporting the shaft so that the framework itself can abut members forming a part of, or fixedly coupled to, frame 10 which ultimately absorbs these forces and which is constructed with sufficient rigidity to withstand the forces without significant deformation.

However, because of the fact that only one lateral backup roll 34 or 35 is provided for work roll 25, and only one roll 40 or 41 for work roll 26, depending upon the direction of passage of strip 28, it is possible for the resultant forces to be in such a direction that the rolls are distorted or forced out of their proper positions unless the rotational axes of the sets of rolls are precisely aligned. Thus, with the strip moving in the direction shown in Figure 2, the central axis of work roll 25 must be aligned with the central axis of rolls 34 and 37 and with a point of contact on the frame and, below the strip the axis of roll 26 must be aligned with those of 40 and 43. If this is not the case, the resultant vector forces are almost certain to cause damage or, at least, premature failure of some portion of the system.

Thus, in accordance with the invention, an arrangement is provided for supporting and adjusting the relationships of these components, a diagram of this portion of the structure being shown in Figure 3, only the lower portion of the apparatus below strip 28 being illustrated. As seen in Figure 3, work roll 26 is in contact with lateral backup rolls 40 and 41 which, in turn, are in contact with the rollers of bearing roller assemblies 43 and 44, respectively.

Roller 41 and bearing assembly 44 are supported in a generally L-shaped cluster arm end support 46. In a similarfashion, roller 40 and bearing assembly 43 are supported in a cluster arm end support 47.

Support 46 is mounted on an axle 48 and support 47 is mounted on an axle 49, axles 48 and 49 being supported as will be described, in a manner which permits the location of the central pivot axis thereof to be adjusted, changing the pivot axis location distance from the strip and adjusting the relationships of the axes of the work and backup rolls. As will be seen in Figures 3,5 and 7, arms 46 and 47 are attached to the frameworks 51 and 52 which are provied with arcuate surfaces 54 and 55, respectively, adapted to contact pillow blocks attached to frame 10, thereby transmitting the forces from the backup rollers directly to the frame. Also as seen in Figure 3, rolls 40 and 41 have end bearings mounted in end blocks 57 and 58, respectively, which are received in elongated U-shaped openings 59 and 60 in supports 46 and 47.Thus, the bearings, end blocks and rolls are free to move toward and away from the rotational axis of work roll 26, but are restrained from vertical motion by the supports.

Figure 5 further illustrates aspects of the structure in accordance with the invention and permits explanation of the operation of the invention as roll diameters are changed. As seen therein, bearing assembly 37 is mounted on a cluster arm end support 67 which is supported on an axle 69 which cluster arm end support 66 supports bearing roller assembly 38 and is supported on an axle 68. Axles 68 and 69 are eccentrically received in splined sleeves 70 and 71, respectively, each of those sleeves being a relatively short member received in a mating splined opening attached to the movable intermediate roll journal boxes 75 and 76. The centers of axles 68 and 69 are sufficiently eccentrically offset so that if the rotational position of its associated splined sleeve is changed, the location of the support centre for the associated cluster arm end support is also changed.The rotational positions of sleeves 70 and 71 can readily be changed by removing a retaining block from the outside, axially extracting the splined sleeve, rotating it a predetermined amount until the teeth again mesh, and reinserting the splined sleeve, all while supporting shaft 68 or 69. Since this is accomplished with no load on the machine, it is a relatively quick and simple procedure. Preferably, the housing adjacent each splined sleeve is provided with a marker, such as the illustrated arrow, and each sleeve is provided with inidicia so that a predetermined amount of adjustment can be accomplished. As illustrated, axles 48 and 49 are similarly supported in splined sleeves 73 and 74, respectively.

It will also be observed that the frame of bearing assemblies 37 and 38 will have arcuate surfaces 64 and 65 for contacting replaceable pillow blocks 61 and 62, respectively, which are attached to members integrally connected with the machine frame 10.

Figure 5 illustrates two circumstances in the top portion of the Figure, that on the right being the circumstance in which the work roll has a radius R3 and the intermediate roll has a radius R1, the central axis of rotation of work rolls 25,35 and 38 being aligned, the equivalent rolls on the other side under those circumstances being assumed to be aligned.

Forces acting through the center of rotation of work roll 25 act generally along an inclined line which passes through the centers of rotation of rolls 35 and 38 and, through the arcuate surface 65, to pillow block 62 and to the frame. Forces oppositely exerted, in the other direction of strip passage, similarly pass through aligned centers.

If we now assume that a smaller work roll having a radius R4 is exerted, and if we further assume that intermediate roll 29 is removed and turned down reducing its radius to R2, it will be apparent that the net effect is the upward movement of the center of rotation of work roll 25. This upward movement would, of course, widen the gap which means that it would be necessary to lower the entire upper portion 16 of the machine or to raise the lower portion; but such raising or lowering equally effects the entire apparatus above the plane of the strip, and therefore has no effect on the relationships being described.

When the center of rotation of work roll 25 is raised with respect to the centers of rotation of roll 34 and bearing roller assembly 37, the result is a misalignment which is more clearly shown in the vector diagram of Figure 6. As seen in that diagram, the angle 02 which results from these changes in radii produces an offset force vector F3 which passes through the axis of roller 34, tending to push that roller downwardly and further out of alignment with the axes of rolls 25 and 37. If this condition were allowed to persist, the bearings supporting the rolls at each end would not survive very long, or other portions of the system would fail.

Accordingly, at the same time that rolls are replaced or ground down so that their radii are significantly affected, adjustments are made in the rotational positions of splined sleeves 70, 71, 73 and 74, adjusting all of the support centers for all four of the cluster arm end supports, thereby lowering or raising the bearing roller assemblies and the lateral backup rolls associated therewith to once again align the axes so that the forces are resolved and so that the resultant lateral force passes through the centers of rotation, eliminating the force vector F3. In the example illustrated in Figures 5 and 6, it would be necessary to lower arms 66 and 67.Because of the fact that surfaces 54, 55, 65 and 64 are not fixedly attached to any portion of the frame, and because of the fact that they are curved, they can readily assume a new position against their associated pillow blocks which is in line with the resultant lateral force. Thus, the forces are transmitted directly through the center lines of the rollers to the frame without causing any damage. It is a relatively simple problem in geometry, given the dimensions of the various components involved, to determine the amount of rotation required for the splined sleeves to compensate for a known change in work roll or intermediate roll radius. It will also be recognized that horizontal adjustment may be necessary to accommodate work rolls of different diameters. This can be accomplished by replacing pillow blocks 61, 62.Alternatively, mechanically adjustable means can be provided in place of the pillow blocks.

Figure 7 shows a partial side elevation along line 7-7, illustrating the positions of shaft 49 and splined sleeve 74 with intermediate roll 30 in the background. As will be recognized, sleeve 74 is kept in place by an end block 76 which can easily be removed to permit axial extraction of the splined sleeve. Figure 7 also illustrates the framework 52 for the bearing roller assembly with rollers 43, the intermediate arms of frame 52 between the rollers having contact surfaces 55 which bear against the associated pillow block.

As will be recognized from the foregoing discussion, the eccentric splined sleeve adjustment technique disclosed herein provides the very significant advantage of permitting the use of only one set of bearing rollers as a final backup for lateral forces from a work roll of a wide variety of diameters. This permits much greater variation in the selection of work roll diameters which is a highly meaningful improvement in itself.

In addition, the structure in accordance with the invention permits the use of a significantly larger set of bearing roller assemblies, an increase in size which could not be accomplished within the available space in arrangements formed in the prior art where two sets of bearing roller assemblies were necessary. The increase in size of the bearing roller assembly greatly lengthens the life, the expected life being a nonlinearfunction of size, increasing out of proportion to the amount of increase.Thus, replacement of the bearing roller assemblies, a very expensive component of the mill, is of great concern, The invention has been described this far in connection with a totally symmetrical mill, i.e., one in which the various rollers, including the work rollers, can be viewed as being substantially identical or mirror images above and below the plane of the strip, orto the left or right of a vertical plane passing through the rotational axes of the work rolls. However, utility of the invention is by no means limited to arrangements of this type. Some examples of other systems with which the invention is usable are illustrated in Figures 8,9, 10 and 11, this collection being by no means exhaustive.The embodiment of Figure 8 is one in which work rolls 25 and 26 act on a strip which passes only in one direction, an arrangement which is useful in many circumstances. The embodiment of Figure 9 is one in which nonsymmetrical reduction, lamination or other treatment is desired, the work roll 25 being employed on top of the strip with the bottom of the strip acted on directly by a somewhat larger intermediate roll. The embodiment of Figures 10 and 11 are similar to Figure 9 in that only the upper surface of the roll is acted upon by a small work roll, the lower surface being supported by, in the case of Figure 10, an intermediate roll and, in the case of Figure 11, directly by the larger backup roll. Any ofthese embodiments can be inverted or reversed.

While certain advantageous embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.

Claims (12)

1. A lateral backup system for a work roll in a rolling mill of the type having a substantially rigid frame for supporting the rolls and at least one vertical backup roll having an axis of rotation in substantially the same plane as the work roll axis, said system comprising a lateral backup roll; a bearing roller assembly having a plurality of rollers axially spaced along a shaft; a substantially rigid mounting structure having a surface for contacting said frame and having means for rotatably supporting said lateral backup roll in contact with one side of said work roll and said rollers of said bearing roller assembly in contact with said lateral backup roll; means for supporting said mounting structure; and means for adjusting the location of said mounting structure supporting means to align the centers of rotation of said work roll, said lateral backup roll and said bearing roller assembly thereby to resolve the resultant lateral forces into a line between the work roll axis and said frame.

2. A system according to Claim 1 wherein said mounting structure comprises a generally L-shaped member having a generally vertical leg and a laterally extending leg, said laterally extending leg having an elongate opening for receiving end bearings for rotatably supporting said lateral backup roll, and said vertical leg having a curved surface on the side thereof opposite said laterally extending leg for contacting said frame.

3. A system according to either of Claim 1 or Claim 2 wherein said means for supporting said mounting structure comprises a shaft mounted on said frame along an axis with said work roll and spaced from the strip path farther than the axes of said lateral backup and bearing roller axis; and wherein said adjusting means includes an eccentric member mounted on said shaft and supporting said mounting structure.

4. A system according to any one of Claims 1 to 3 comprising a second lateral backup roll, bearing roller assembly, mounting structure and adjusting means repeated in mirror image on the opposite side of said work roll.

5. A system according to any one of Claims 1 to 3 comprising a second work roll, lateral backup roll, bearing roll assembly, mounting structure and adjusting means repeated in mirror image on the opposite side of the strip path.

6. A rolling mill arrangement comprising a frame; an opposed pair of work rolls on opposite sides of a strip path; a main intermediate roll and a backup roll for each of said work rolls having their axes of rotation in substantially the same plane as said work rolls; four lateral backup rolls, one on each side of each work roll, in rolling contact with its associated work roll; four bearing roller sets, each set being in rolling contact with one of said lateral backup rollers; four support means, each said support means supporting one each of said backup rolls and said bearing roller sets, each of said support means having a surface contacting said frame; and means for adjustably supporting each of said support means to permit alignment of the rotation axes of each contacting pair of backup a backup roll and a bearing roller set with the axis of the associated work roll into a single plane.

7. A rolling mill arrangement comprising a work roll adjacent a strip path; at least one larger backup roll having a rotational axis vertically aligned with the axis of said work roll; a lateral backup roll beside and contacting said work roll; a bearing roller set beside and contacting said lateral backup roll; and means for adjustably supporting said lateral backup roll and said bearing set such that the axes of rotation thereof lie in the same plane with each other and with said work roll.

8. A rolling mill arrangement according to Claim 7 comprising a second lateral backup roll on the other side of and contacting said work roll; a second bearing roller set beside and contacting said second lateral backup roll; and means for adjustably supporting said second lateral backup roll and said second bearing roller set such that the axes of rotation thereof lie in the same plane with each other and with said work roll.

9. A rolling mill arrangement comprising a work roll adjacent a strip path; at least one larger backup roll having a rotational axis vertically offset from the axis of said work roll; a lateral backup roll beside and contacting said work roll; a bearing roller set beside and contacting said lateral backup roll; and means for adjustably supporting said lateral backup roll and said bearing roller set such that the axes of rotation thereof lie in the same plane with each other and with said work roll.

10. A rolling mill arrangement according to Claim 9 and including a second work roll on the opposite side of said strip path; and a second lateral backup roll, a second bearing roller set and means for adjusting said second backup roll and roller set arranged adjacent said second work roll in mirror image to the first work roll, lateral backup roll and bearing roller set.

11. A rolling mill substantially as hereinbefore described with reference to and as shown in Figures 1 to 4 of the drawings.

12. A backup system for a work roll in a rolling mill, substantially as hereinbefore described with reference to and as shown in Figures 5 to 11 of the drawings.