Rolling mill with roll deflection bi-dimensionally controlled

Details Rolling mill with roll deflection bi-dimensionally controlled Rolling mill with roll deflection bi-dimensionally controlled

2000-05-10

2001-07-17

Butler, Rodney A. (Department: 3725)

Metal deforming

By use of roller or roller-like tool-element

With carrier for roller-couple or tool-couple

Reexamination Certificate

active

06260397

ABSTRACT:

FIELD OF THE INVENTION
The invention generally relates to a rolling mill for producing plate and strip, and in particular to a rolling mill in which a roll's flexure is controlled in two-dimensional directions, thereby the rolled plate and strip have very high thickness precision in cross section.
BACKGROUND OF THE INVENTION
Generally, there are a variety of kinds of rolling mills for rolling plate and strip, and they are classified according to the number of rolls into the two-high mill, the four-high mill and the cluster mill, but the most commonly used rolling mills are the four-high mill, the HC mill and the cluster mill and so on. For two-high type, four-high type mills, there exist many disadvantages, the main disadvantage is that: when a rolled piece passes the mill stand, since the pressing devices are located at the necks of the rolls, the rolls are caused to have larger bending deformation, and the deformations of the rolls will result in the thickness error in the cross section of the rolled piece (rolled plate and strip), thus seriously affecting the quality of the rolled piece. To solve the above problem, the method of increasing the diameter of the rolls has to be adopted, and for a four-high mill, also the method of increasing the diameter of the supporting rolls has to be adopted. However, as the diameter of the rolls increases, it is certain to cause the rolling forces to abruptly increase, and the change of the rolling forces in turn causes an increase of the bending deformation of the rolls.
The cluster mills include integral housing type mills and open type mills (as shown in
FIGS. 1
,
2
), Japanese Patent 54-1259 discloses a cluster mill which adopts a tower-like roll system. Of course, such rolling mills all have the advantage of high rigidity, but in a cluster mill, the portions of the mill stand which contact the supporting rolls still have bending deformation under rolling forces, thus causing the flexural deformation of the working rolls and affecting the uniformity of the thickness of rolled piece as a result.
The solution to the problem of the roll's flexural deformation to reduce or eliminate the effect of the roll's flexural deformation on the thickness of rolled piece consists in the control of the shape of the clearance between the working rolls to make the flexural deformation of the working rolls not to be affected by the change of rolling forces. A Chinese Patent (application number 89101393, issuance number CN 1013250B) discloses “A rolling mill with rolls of small flexure and high rigidity”. To achieve above object, according to the patent, the supporting rolls at the outmost layer of the tower-like roll system are supported on the roll supports in the form of a mufti-section beam; rolling forces acting on the working rolls are transmitted respectively to the upper and lower roll supports via the roll systems; the vertical component of the force borne by the roll supports are transmitted to the mill stand via the downward acting or upward devices or similar elements such as pads; the number of the downward acting or upward acting devices is at least two, and the positions of the downward acting or upward acting devices are in the middle region of the axis of the working roll on the roll supports. It can be seen, the solution of that patent can make the flexural deformation of the roll supports in the vertical plane substantially not to vary with the rolling forces, thus effectively reducing the thickness error in the cross-section of the rolled piece. However, for the cluster mills with a tower-like roll system, the force transmitted from the working rolls to the intermediate rolls has vertical and horizontal components, therefore the peripheral supporting rolls also bear significant horizontal component force. For the rolling mill disclosed in Chinese Patent No. 89101393, the horizontal component force causes the roll supports to have horizontal flexural deformation, thus causing the intermediate rolls as well as the working rolls to have larger flexural deformation.
As stated above, for solving the problem of flexural deformation of the working rolls of a cluster mill, it is not only necessary to reduce the flexural deformation produced by the vertical component force, but also that produced by the horizontal component force, that is, it is obliged to solve the problem of deformation in two-dimensional directions, so that a working roll can be held straight and the thickness precision in the cross-section of the rolled piece is increased.
SUMMARY OF THE INVENTION
Therefore, the invention is aimed to solve the problem of the two-dimensional flexural deformation of the rolls, namely, the invention can reduce not only the flexural deformation in vertical direction, but also that in horizontal direction. Accordingly, the object of the invention is to provide a high-precision rolling mill, as compared with the prior art, when the rolling mill of the invention is subjected to the rolling force, the flexural deformation of the rolls can be greatly reduced, resulting in the reduction of the thickness error in the cross-section of the rolled piece and the increase of the dimension accuracy of the rolled piece.
To achieve the above-mentioned object, the embodiment of the invention is as follows: the rolling mill for rolling plate and strip comprises a mill stand, an upper and a lower roll systems and an upper and a lower roll supports. The mill stand is of a frame shape and is able to bear rolling forces, and all parts and components of the rolling mill, such as the roll systems, are incorporated in the frame. The roll system is so arranged as to be of a tower-like configuration. The roll system is composed of three parts, a working roll, supporting rolls and intermediate rolls; the upper and lower supporting rolls disposed at the outmost layer of the roll system are respectively supported on the upper and lower roll supports in the form of a mufti-section beam, and the upper roll support can be moved up and down if necessary to adjust the magnitude of the clearance between the rolls. The rolling mill is characterized in that the mill stand, the roll supports and the intermediate supporting means between the frame and the roll supports commonly compose a two-dimensional supporting system. The intermediate supporting means is disposed on at least one of the upper and lower roll supports and is arranged in the region of the middle part of the roll body axis of the working roll with its length being not longer than the length of the roll body of the working roll. The intermediate supporting means includes pressing devices and horizontal pads; there are at least two pressing devices disposed above the upper roll support and placed in the mill stand, the lower roll support is supported by horizontal pads, and both the pressing devices and the horizontal pads are arranged in the region of the middle part of the roll body axis of the working roll on the roll support. In the invention there are also disposed upper and lower vertical pad sets along a horizontal direction, which are respectively positioned between the two side walls of the upper and lower roll supports and supported on the side walls of the mill stand, and the upper and lower vertical pad sets are respectively composed of two wedge-shaped menders to prevent the flexural deformation due to the horizontal component force. The shape of the mill stand is mated with that of the roll supports.


REFERENCES:
patent: 5596899 (1997-01-01), Sendzimir et al.
patent: 5609054 (1997-03-01), Ogawa et al.
patent: 5666844 (1997-09-01), Bieber
patent: 5692407 (1997-12-01), Kajiwara et al.
patent: 2045332U (1989-10-01), None
patent: 1041122A (1990-04-01), None
patent: 2228811Y (1996-06-01), None
patent: 2250822Y (1997-04-01), None
patent: 487759 (1938-06-01), None

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