JPH065703U - Backup roll device for rolling mill - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a backup roll device that allows the backup fulcrum to be changed arbitrarily, and that the change operation is easy and the fulcrum positioning is reliable. [Structure] A pair of cylinders which are rotatable and axially slidable on both sides of the cylinder length of a backup shaft fixedly supported by the housing of a rolling mill to a cylindrical shaft portion having a diameter smaller than that of the central cylindrical portion and rollingly contacting an intermediate roll. Attach a separation support roll of short width. The separation support roll is mounted on a backup shaft through a slide bearing, and the support roll is configured to be individually movable in the axial direction at high speed by a hydraulic cylinder installed in the backup shaft bearing. And the thrust bearing is arranged in the frame of the connecting portion provided on the outer side surface of the support roll.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 INDUSTRIAL APPLICABILITY The present invention is used in the field of iron and steel and non-ferrous metals, and is used in a rolling mill for forming a desired plate thickness by passing a plate material such as a steel plate between rolls to perform plastic deformation. The present invention relates to a device for making a backup when performing roll bending.

[0002]

[Prior art]

 Generally, various methods have been proposed to control the shape of the material to be rolled. For example, in a four-high rolling mill, a pair of work rolls having a relatively small diameter are sandwiched from the outside. It is equipped with a backup roll with a relatively large diameter, both of which are formed to have approximately the same cylinder length so that they can roll over the entire length, and a bending cylinder is installed between the bearings of the work rolls. .

The material to be rolled is passed through such a rolling mill to obtain a strip material having a desired plate thickness. As the material to be rolled passes, the central portion of the work roll is expanded, Since the material to be rolled has a so-called middle-high cross-sectional shape with a thick central part and thin side edges, a crown is formed on the backup roll and the bending cylinders act to expand the necks of the work rolls mutually. The work roll is adjusted in such a way that the pressure lower surface of the work roll becomes flat, and shape control is performed to correct the crown generated in the rolled material.

[0004]

[Problems to be solved by the device]

 However, in the above conventional rolling mill, since the work rolls and intermediate rolls are constrained on the entire surface of the back-up rolls, it is difficult to give sufficient roll bending to the work rolls, and absolute shape control capability is lacking. Not only that, but especially in a four-high rolling mill, there is a drawback in that it is necessary to change the crown shape by changing the backup roll depending on the strip width, strength and shape of the material to be rolled. In addition, since the backup roll rolling on the work roll and the intermediate roll comes into full contact, the backup fulcrum cannot be changed arbitrarily and the shape cannot be controlled at any position. In addition, it is necessary to polish the entire surface of the backup roll in terms of maintenance, and there are drawbacks that maintenance is difficult and sufficient space is required on the side of the rolling mill due to the shift mechanism of the intermediate roll.

As a method of solving such a drawback, the backup roll device has a backup shaft arranged in parallel with the work roll, which is separated into right and left in the roll axial direction and has a body length to be rolled. A pair of support rollers, which are formed shorter than the plate width of the material, are mounted so as to be slidable in the axial direction. The pair of support rolls are rolled onto the work rolls and serve as backup support for the work rolls during rolling. Similarly, the lower back-up roll device also has a back-up shaft and a pair of left and right support rolls attached to the back-up shaft. I have to. The support roll is mounted on a backup shaft via a rotary bearing using rollers or rollers, and thrust bearings are arranged on both end faces.

In such a rolling mill, although there is an advantage that the roll bending effect can be sufficiently exerted without being restricted by the conventional full-contact type backup roll, the pair of support rolls are moved inward. In such a case, since thrust bearings are provided on both end faces of each support roll, the pair of support rolls cannot be brought closer by the thrust bearings provided on the inner side surface of each support roll. For this reason, the roll bending effect cannot be fully exerted on a narrow material to be rolled. Since the thrust bearings are installed on both end faces of the pair of support rolls, the width of the support rolls cannot be made long. Therefore, the Hertzian stress between the intermediate roll or work roll and the support roll becomes high, causing problems such as damage to the surface of the support roll and shortening of the roll life. The outer diameter of the backup roll becomes large because of restrictions in manufacturing the rotary bearing. It is difficult to disassemble and assemble the rotating bearing that has been fully manufactured. It is difficult to control the clearance between the inner diameter of the rotating bearing and the backup shaft. If the backup shaft thermally expands due to thermal expansion, the support roll may not be able to move horizontally. If the work roll bends during rolling, the backup shaft also bends, which may cause the rotary bearing to seize. Such drawbacks still remain.

[0007] The purpose of the present invention is to pay attention to the above-mentioned conventional problems, in particular, to have a quick response to the condition that changes momentarily in high-speed rolling, and to greatly increase the bending control amount especially for work rolls or intermediate rolls. Support roll of the rolling mill, which can improve the shape control ability, have a large effect of reducing the edge drop, and can perform shape control at any position in the strip width direction of the rolled material. To provide a device.

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the backup roll device of the rolling mill according to the present invention rolls a pair of work rolls that roll down the rolled material, a pair of intermediate rolls that roll to each work roll, and further rolls to an intermediate roll. It is equipped with a backup roll and both end bearings of each roll are attached to the housing, and the pressurizing means for crown control by adjusting the bearing interval between the pair of work rolls and the intermediate roll is installed in the housing. In this rolling mill, a pair of separation support rolls with a short cylinder width, which are separated from each other in the axial direction of the backup shaft, are installed on both sides of the cylinder length of each of the backup rolls. A backup roll that supports a support roll so that it can slide in the axial direction. The support roll is fixedly supported by the backup cylinder, and the support roll is mounted on the backup shaft through a slide bearing. Inside the frame of the hydraulic cylinder installed in the backup shaft bearing and the connecting portion provided on the outer side surface of the separation support roll. Thrust bearing is arranged in the structure.

[0009]

[Action]

 According to the above configuration, the function of each back-up roll, which suppresses the work roll deflection that directly rolls down the material to be rolled, is to install the pair of support rolls that are rolled on the work roll and separated in the roll axial direction. It is demonstrated by the backup shaft that is installed and supports the work roll rolling force. The pair of separate support rolls are individually movable in the axial direction, and the bending moment fulcrum is changed by moving the positions, and the amount of roll bending is adjusted by the bending means provided on the work roll neck. be able to. Therefore, the overall bending amount is controlled by the position movement of the support rolls, the shape of the rolled material such as the crown can be controlled, and the bending moment fulcrum can be changed arbitrarily, so the shape control capability is improved. Greatly improved.

Particularly in this invention, since the backup shaft is formed in a cylindrical shape, the structure is simple, the cross-sectional performance of the backup shaft can be increased, and the deflection of the shaft can be minimized. Therefore, regardless of the position of the support roll, a uniform fixed load is applied to the inner peripheral surface of the support roll, and since the sliding bearing makes surface contact with the backup shaft, seizure occurs even under high rolling load. The support roll can be held in a stable manner without any concern, and the bending fulcrum can be set reliably. In addition, since the cross-sectional performance of the backup shaft is large, it is possible to give the backup sufficient supporting force and set a high rolling load. In addition, the support roll can be moved axially at high speed by a hydraulic cylinder in the backup bearing.

Further, since the deep groove type ball bearing, which is a thrust bearing, is arranged on the outer end surface of the support roll, the support roll can be sufficiently moved inward, and it can be used for a narrow material to be rolled. Can also fully exert the roll bending effect. Furthermore, since the support roll has a long body width, the Hertzian stress between the intermediate roll or work roll and the support roll is reduced, damage to the roll surface can be prevented, and roll life is extended.

[0012]

【Example】

 Hereinafter, a specific embodiment of a backup roll device for a rolling mill according to the present invention will be described in detail with reference to the drawings.

4 to 5 show the overall configuration of a rolling mill equipped with a backup roll device according to the embodiment. As shown in the figure, this rolling mill has a pair of upper and lower work rolls 21 and 22 which are parallel to a gate-shaped housing 20 and are horizontally mounted so as to be capable of rolling contact with each other. It is possible. A pair of intermediate rolls 24 and 26, which are relocated so as to be sandwiched between the upper and lower work rolls 21 and 22 in parallel from above and below, are horizontally mounted on the housing 20. The intermediate rolls 24 and 26 are formed to have a diameter larger than that of the work rolls 21 and 22 to transmit the rolling force. Especially, the body length is set to be equal to or larger than the plate width of the material 23 to be rolled, and It is set to be shorter than the body length of the work rolls 21 and 22. Therefore, when the intermediate rolls 24 and 26 are in full contact with the work rolls 21 and 22 when assembled in the housing 20, the end portions of the work rolls 21 and 22 are, as shown in FIG. It is set so as to protrude from the end of 26 by a predetermined length.

In addition to such a roll row, an upper backup roll device 28 and a lower backup roll device 30 are also laid horizontally in parallel so that the intermediate rolls 24 and 26 are sandwiched between them. .

The upper backup roll device 28 has a back-up shaft 32 arranged in parallel with the intermediate roll 24, which is separated into right and left in the roll axial direction and has a body length shorter than the plate width of the material 23 to be rolled. The pair of formed support rolls 34R and 34L are attached so as to be slidably movable in the axial direction. The pair of support rolls 34R, 34L are rollingly contacted with the upper intermediate roll 24 and serve as a backup support for the work roll 21 and the intermediate roll 24 during rolling. Similarly, the lower back-up roll device 30 also has a backup shaft 36 and a pair of left and right support rolls 38R and 38L attached to the backup shaft 36, which are rolled to the lower intermediate roll 26 during rolling. I am trying to make backup support.

Further, the support rolls 34R, 34L, 38R, 38L are mounted on the backup shaft 32 via slide bearings 40L, 40R as shown as a representative of the upper backup roll device 28 in FIG. Thrust bearings 42L and 42R of deep groove type ball bearings are arranged on the outer end surface thereof. For the slide bearings 40L and 40R, materials such as phosphor bronze, aluminum bronze, oil-impregnated sintered alloy, solid lubricant embedded high strength brass alloy, etc. are used. The slide bearings 40L and 40R are made of these materials and are formed into a cylindrical shape so that they can entirely contact the outer peripheral surfaces of the backup shafts 32 and 36, and are mounted by, for example, shrink fit or bolts. It

The backup shaft 32 is non-rotatably fixedly supported by the bearing 50 via a key 50a. The outer peripheral surface of the backup shaft 32 and the inner peripheral surfaces of the separation support rolls 34R, 34L have a nitriding treatment, a carburizing treatment, a ceramic treatment, or the like in order to improve surface hardness, wear resistance, heat resistance, and lubricity. It is possible to carry out one desired type of surface treatment from vapor deposition and chemical densification. The clearance between the outer diameter of the backup shaft 32 and the inner diameters of the separation support rolls 34R and 34L is such that the separation support rolls 34R and 34L can move horizontally even if the backup shaft 32 thermally expands. As described above, the surface treatment is not limited to both the outer peripheral surface of the backup shaft 32 and the inner peripheral surfaces of the separation support rolls 34R, 34L, and the outer peripheral surface of the backup shaft 32 or the separation support rolls 34R, Surface treatment may be performed on either of the inner peripheral surfaces of 34L.

As shown in FIG. 5, the neck portions of the upper and lower work rolls 21 and 22 and the intermediate rolls 24 and 26 and the neck portions of the backup shafts 32 and 36 of the upper and lower backup roll devices 28 and 30 are Bearings 46, 47, 48, 49, 50, 52 are mounted, and these are mounted in the housing 20 in tandem. Further, a rolling-down cylinder 54 is provided at a lower position of the housing 20, and a predetermined rolling pressure is generated between the work rolls 21 and 22 by driving the rolling-down cylinder 54.

In such a rolling mill, a specific configuration of the backup roll devices 28 and 30 according to this embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 shows the upper backup roll device 28, in which the central cylindrical portion 32a of the backup shaft 32 has a large cross-sectional performance and minimizes the plate thickness variation of the rolled material. Further, the separation support rolls 34R and 34L slide on the shaft portions 32b on both sides of the back-up shaft 32 so that their positions can be adjusted by sliding movements in the roll axial direction. For this position movement, hydraulic cylinders 81 and 82 as drive members are formed in the bearing 50 of the backup shaft 32 on the separation support rolls 34R and 34L. Further, the separation support rolls 34R and 34L are set so that the separation support rolls 34R and 34L are not tilted during the movement thereof due to the frictional force between the separation support rolls 34R and 34L and the intermediate roll 24 in contact therewith. By supplying and discharging pressure oil, the thrust bearing support 62 (62L, 62R), which is the frame of the connecting portion between the hydraulic cylinders 81, 82 and the separation support roll 34, is pushed and pulled, and the central cylindrical portion of the backup shaft 32 during rolling. The separation support rolls 34R and 34L can be moved with respect to 32a.

Such a configuration is also the same in the lower backup roll device 30. Reference numeral 90 is a bellows.

Further, a work roll bending device 100 and an intermediate roll bending device 200 are incorporated in the housing 20, which is shown in FIG.

First, the work roll bending apparatus 100 includes an upper roll bending rod 102, a lower roll bending rod 104, a roll bending cylinder block 106, and a piston 108. A lower end portion of the upper roll bending rod 102 is fixed to a piston 108, and an upper end portion thereof is disposed so as to come in contact with and separate from the upper work roll bearing 46. On the contrary, the lower roll bending rod 104 has an upper end fixed to the piston 108 and a lower end that can be brought into contact with and separated from the lower work roll bearing 47. The piston 108 is built in the bore portion 107 of the cylinder block 106, and the bore portion 107 is located in the middle of both pistons 108 and has a small diameter communication hole 110. The pressure oil is supplied from a pressure oil supply device (not shown). Is introduced, the roll bending rods 102 and 104 are separated from each other, and act to press the bearings 46 and 47 of the upper and lower work rolls 21 and 22 toward the bearings 48 and 49 of the intermediate rolls 24 and 26, respectively. .

Similarly, in the intermediate roll bending device 200, a bore portion 207 independent of the bore portion 107 is bored in the cylinder block 106, and a pair of pistons 208 are slidably attached to the bore portion 207. . An upper roll bending rod 202 and a lower roll bending rod 204 are connected to each piston 208, and the tips of these rods 202 and 204 are projected from the cylinder block 106 to abut the intermediate roll bearings 48 and 49. It is possible. The bore portion 207 is also provided with a small-diameter communication hole 210 in the center thereof, and by introducing pressure oil from the pressure oil supply device into this, the roll bending rods 202 and 204 separate from each other, and the intermediate roll 24 , 26 of the upper and lower backup roll units 28, 30 are pressed against the bearings 50, 52 of the upper and lower backup roll units 28, 30, respectively.

Liners 112 and 114 are attached to the sliding surfaces of the roll bending cylinder block 106 and the upper and lower work roll bearings 46 and 47, respectively, and the sliding is performed when pressure oil is supplied to the cylinder block 106. The surface is slid to reduce the sliding resistance between the work roll bearings 46 and 47 and the cylinder block 106.

As shown in FIG. 5, the reduction cylinder 54 has a built-in head 116, and at the time of compression, the pressure oil is introduced into the pressure reduction cylinder 54 from a pressure oil supply device (not shown) to move the head 116. I am trying to raise it. The operation of the head 116 pushes up the backup shaft bearing 52 of the lower backup roll unit 30, and the reduction force is the lower backup shaft 36, the lower intermediate roll 26, the lower work roll 22, the upper work roll 21, the upper intermediate roll 24, It is transmitted to the upper backup shaft 32, the upper backup shaft bearing 50, and the housing 20 to generate a desired rolling force.

The operation of the rolling mill configured as described above is as follows. Before rolling, the positions of the separation support rolls 34R, 34L and 38R, 38L are determined in advance according to the width of the material 23 to be rolled. In this case, the rolling contact position of the separation support rolls 34 and 38 to the work rolls 21 and 22 is set to a position where it is superposed on the side portion of the material 23 to be rolled. After that, the work rolls 21, 22 and the intermediate rolls 24, 26 and the support rolls 34, 38 are brought into light contact with each other by using the roll bending rods 102, 202 and a roll balancing cylinder (not shown). Then, after that, the position adjusting hydraulic cylinders 81, 82 of the separation support rolls 34, 38 are driven to move to the preset positions. As a result, the distance between the pair of separation support rolls 34R, 34L and 38R, 38L is set to a desired distance.

After this initial setting is completed, the rolled material 23 is passed between the work rolls 21 and 22. When the rolled material 23 is passed, the separation support rolls 34 and 38 are pressed against the backup shafts 32 and 36 and the intermediate rolls 24 and 26 via the work rolls 21 and 22, respectively.

As a result, the material to be rolled 23 is rolled into a strip having a desired thickness in the highly rigid portion of the backup shaft central cylindrical portion 32a, and is output as a strip material. A non-contact method using light or magnetism is used. When the ear extension or the middle extension occurs due to this determination, the hydraulic cylinders 81 and 82 are operated so that the paired separation support rolls 34R and 34L and 38R and 38L are brought close to each other or independently. Alternatively, it is possible to obtain a rectangular strip material by adjusting the bending moment amount acting on the work rolls 21 and 22 through the intermediate rolls 24 and 26 by moving them so that they are separated from each other, suppressing the occurrence of abnormal shape. it can. At this time, since the bending amount of the intermediate rolls 24, 26 is controlled by adjusting the bending force of the intermediate roll bending device 200, the amount of position movement of the separation support rolls 34R, 34L and 38R, 38L is controlled. A large shape correction function can be exerted by the interaction with. That is, the correction area can be adjusted by the position movement of the separation support rolls 34R, 34L and 38R, 38L, and the correction amount can be adjusted by the intermediate roll bending device 200.

When the rolled material 23 has an edge drop, the bending force of the work rolls 21 and 22 by the work roll bending device 100 is controlled. Since both ends of the work rolls 21 and 22 project from the intermediate rolls 24 and 26, by supplying pressure oil to the bending device 100, the rods 102 and 104 project and the protrusions from the edges of the intermediate rolls 24 and 26. The part is largely bent and acts to control the edge drop. Of course, since the work rolls 21 and 22 also have rigidity, the bending force is transmitted to the intermediate rolls 24 and 26.

According to the rolling mill of such an embodiment, the bending fulcrums of the work rolls 21 and 22 or the intermediate rolls 24 and 26 can be freely changed, so that the work rolls 21 and 22 or the intermediate rolls 24 and 26 can be restrained by the conventional full-contact backup roll. Not only can the roll bending effect be fully exerted, but the shaft diameter of the backup shaft central cylindrical portion 32a is made larger than the diameter of the shaft portion 32b of the backup shaft 32 to increase the rigidity. The plate thickness of is also accurately maintained. Further, since the positions of the upper and lower separation support rolls 34R, 34L and 38R, 38L can be individually changed, the shape can be controlled at any position in the plate width direction. Therefore, in addition to shape defects such as medium elongation and edge elongation of the rolled material, it is possible to control not only the shape failure of the composite elongation that is a composite of the two.

Further, since the work roll bending device 100 and the intermediate roll bending device 200 are provided, the plate full width shape control is performed by the intermediate roll bending, and the plate end shape control such as edge drop is performed by the work roll bending. Therefore, the control operation becomes very easy. Further, since the positions of the separation support rolls 34R, 34L and 38R, 38L can be symmetrically operated in the vertical and horizontal directions, the shape control can be performed symmetrically in the plate thickness direction and the plate width direction of the material 23 to be rolled, which is excellent. It is possible to obtain rolled products with high accuracy.

In addition, since the positions of the separation support rolls 34R, 34L and 38R, 38L can be freely adjusted by the plate width, the contact surfaces between the work rolls 21 and 22 and the plate width end portions can be more effectively combined with roll bending. It can be made smooth and the edge drop prevention effect is high. Further, since the intermediate rolls 24 and 26 are provided, the diameters of the work rolls 21 and 22 can be made small, so that the rolling load area can be reduced, and thus high pressure rolling can be performed, and the deflection amount of the work rolls 21 and 22 can be reduced. Also, the flat deformation of the roll can be reduced. Further, since the plate thickness and the plate width direction can be controlled symmetrically, the rolled material 23 does not meander when it is threaded, and there is an effect that stable threading characteristics can be obtained.

In the above embodiment, an example of application to the 6-high rolling mill provided with the intermediate rolls 24 and 26 is shown, but it can be applied to the backup roll of the 4-high rolling mill shown in FIG. 7 (1). The diameter of the work rolls 21 and 22 as shown in FIG. 2 (2) can also be applied to a roll having a diameter larger than that of the intermediate rolls 24 and 26. It can also be applied to the backup roll of a cluster rolling machine as shown in Fig. 3 (3). Further, as shown in FIG. 4 (4), it can also be applied to a back-up roll of a rolling mill in which a support roll is fixed to only one side of each back-up shaft 32, 36. Of course, although not shown, it is needless to say that the present invention can be applied to any rolling mill having other special structure, such as a rolling mill having the backup roll device of the embodiment only on the upper portion. Further, although the pair of support rolls 34R and 34L or the pair of support rolls 38R and 38L are applied in the above-described embodiment, the invention can be applied to a rolling mill having a plurality of support rolls 34 and 38 such as three rolls and four rolls. Is. Further, although the ball bearing is used as the thrust bearing in the above embodiment, a cross roller bearing or the like may be used.

[0034]

[Effect of device]

 As is clear from the above description, in the back-up roll device of the rolling mill according to the present invention, a pair of work rolls for rolling down the rolled material, a pair of intermediate rolls for rolling contact with each work roll, and an intermediate roll. And a back-up roll that rolls into the housing. Both end bearings of each roll are attached to the housing, and the pressing means for crown control by adjusting the bearing spacing between the pair of work rolls and the intermediate roll is installed in the housing. In a compact rolling mill, a pair of separation support rolls with a short cylinder width, which are separated in the roll axial direction of a backup shaft that has a cylindrical shape with a diameter smaller than the central cylinder on both sides of the cylinder length of each back-up roll, are installed. It is a backup roll that supports this separation support roll so that it can slide in the axial direction. The shaft is fixedly supported by the housing, the support roll is mounted on the backup shaft via a slide bearing, and the hydraulic cylinder installed in the backup shaft bearing and a connecting portion provided on the outer side surface of the separation support roll. By arranging the thrust bearing in the frame, the bearing is not interposed between the back-up shaft and the separation support roll, so there is no restriction in manufacturing the bearing as in the past, and the backup shaft and the separation support roll are The clearance can be easily obtained, and even if the backup shaft thermally expands, it does not affect the horizontal movement of the separated support roll. In addition, the plate thickness accuracy of the rolled material is improved in the highly rigid part of the central part of the backup shaft, and the horizontal movement of the separation support rolls installed at both ends of the backup shaft greatly increases the bending amount of the work roll or intermediate roll. This is an excellent effect that the shape control ability is improved, the edge drop is greatly reduced, and the shape of the material to be rolled can be controlled at any position in the plate width direction. Is obtained. In particular, since the support roll is driven by the hydraulic cylinder, the shape control effect is high. In particular, the hydraulic cylinder can be set so as to prevent it from tilting due to the contact friction of the support roll. You can have power.

[Brief description of drawings]

FIG. 1 is a sectional front view of a main part of a backup shaft device for a rolling mill according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a front view of the rolling mill according to the embodiment.

FIG. 5 is a side view of the rolling mill.

FIG. 6 is a cross-sectional view of a roll bending device of the rolling mill.

FIG. 7 is an example of another rolling mill on which the back-up roll device according to the embodiment can be mounted.

[Explanation of symbols]

 20 Housing 21, 22 Work Roll 23 Rolled Material 24, 26 Intermediate Roll 28, 30 Backup Roll Unit 32, 36 Backup Shaft 32a Backup Shaft Central Cylindrical Part 32b Backup Shaft Shaft 34R, 34L, 38R, 38L Separation Support Roll 40R , 40L plain bearing 42R, 42L thrust bearing 46, 47, 48, 49, 50, 52 bearing 54 reduction cylinder 81, 82 hydraulic cylinder 100 work roll bending device 200 intermediate roll bending device

Claims (1)

[Scope of utility model registration request] 1. A pair of work rolls for rolling down a rolled material, a pair of intermediate rolls for rolling contact with each work roll, and a backup roll for rolling contact with the intermediate roll are provided, and both end bearings of each roll are mounted on a housing. In a rolling mill in which a pressurizing means for adjusting the bearing intervals between the pair of work rolls and the intermediate roll to control the crown is installed in the housing, both sides of the body length of the backup rolls are central cylindrical portions. A backup roll which has a smaller diameter cylindrical backup shaft and which is equipped with a pair of separation support rolls with a short body width that are separated in the axial direction and supports the separation support rolls so that they can slide in the axial direction. Is fixedly supported by the housing, and the support roll is slid on the backup shaft. A backup of a rolling mill, characterized in that a thrust bearing is arranged in a frame of a connecting portion provided on an outer side surface of the separation support roll and a hydraulic cylinder installed in the backup shaft bearing, which is mounted via a bearing. Roll device.