A MILL FOR ROLLING STRIPS OR PLATES

Abstract: A mill for rolling strips or plates comprises frames of the rolling stand, upper and lower crossbeams, screw-down means, upper and lower roll groups and roll chocks. The upper/lower crossbeam is respectively mounted on the upper/lower side of the frames, to which the screw-down means are fixed, and the screw-down means are located at the end portions of the upper crossbeam to enable the latter to move for adjusting roll gap. The roll chocks and the upper and lower roll groups are arranged between the roll chocks and the crossbeams, and the bearings are provided between the upper/lower roll groups and the roll chocks. Both the bearings and the supporting blocks are positioned at the middle part of the rolls and in the area of the roll bodies.

Description: Field of the Invention The invention relates to a rolling mill for producing plate or strip, and more particularly relates to a rolling mill in which a roll is supported by a central support for controlling the flexure of the roll, thereby the rolled plate or strip has a high thickness precision in their cross sections. Background Art There are a variety of rolling mills for rolling plate or strip. The most commonly used rolling mills are two-high rolling mills, four-high rolling mills and HC mills. These conventional rolling mills have some drawbacks. When a rolled piece passes the mill stand, a larger flexural deformation on the rolls is resulted since the necks of the rolls are subjected to tremendous rolling force. The deformations of the rolls will result in the thickness error in the cross section of the rolled piece (rolled plate or strip), thus seriously affecting the quality of the rolled piece. To solve the above problem, it has been suggested to increase the diameter of the rolls. As for the four-high rolling mills and HC mills, it has been suggested to increase the diameter of the supporting rolls. However, as the diameters of the rolls increase, it will result in an abrupt increase in the rolling force. The change of the rolling force in turn causes an increase of the flexural deformation of the rolls, which still result in a larger thickness error in the cross section of the rolled piece. (see for example GB-A-379584). Object of the Invention Therefore, the invention is aimed to solve the above problem of the flexural deformation of the roll barrels. The object of the invention is to provide a high precision rolling mill for rolling plate or strip, wherein the flexural deformation of the rolls is reduced significantly, thereby the dimension accuracy of the rolled piece is highly increased. Summary of the Invention The object of the present invention is achieved by providing a rolling mill for rolling plate or strip comprising a mill stand, an upper crossbeam and a lower crossbeam, a pressing device, roll seats, upper roll system, and lower roll system, wherein said upper and lower crossbeam are mounted on the upper and lower end of the mill stand respectively, said pressing device being mounted on the mill stand corresponding to the two ends of the crossbeam and being capable of moving at least one of the upper and lower crossbeams for adjusting the magnitude of the clearance between the two rolls, the upper and the lower roll system and at least one of the roll seats being disposed between the upper and lower crossbeams, supporting pads being disposed between the roll seats and the upper and the lower crossbeams, bearings being disposed between the roll systems and the roll seats, and said supporting pads and said bearings being positioned to align to the central portion of the roll systems within the range of the rolls' length. Preferably the bearings are arc-shaped sliding bearings. According to another aspect of the present invention, there is provided a rolling mill for rolling plate or strip comprising a mill stand, an upper crossbeam and a lower crossbeam, a pressing device, roll seats, an upper roll system and a lower roll system, wherein said upper and lower crossbeam are secured on an upper end and a lower end of the mill stand respectively, at least one roll seat and upper and lower roll system are provided between the upper and the lower crossbeam, and said pressing device is provided on the central portion of the at least one of said upper and lower crossbeams, the pressing device is capable of moving the roll seats, which is in contact with the pressing device, up and down for adjusting the clearance between two rolls, bearings are provided between the roll seats and the upper and the lower roll systems, and said bearings are located to align to the central portion of the roll systems within the range of rolls' length. In the present invention, since the supports is provided to align to the central portion of the rolls rather than on the roll's two end necks of the prior art to the center portion. Namely, by means of arranging the supporting devices such as bearings, supporting pads or pressing devices etc. in the region corresponding to the central portion of the roll body axis of the working roll, the flexural deformation of the rolls would reduce significantly during the rolling operation. As a result, the thickness error in the cross section of the rolled piece will reduce and the dimension accuracy will increase. Brief Description of the Drawings The embodiments of the present invention will be described in detail in combination with the accompanying drawings. In the drawings: Fig. 1 is a front schematic view of the first embodiment of the invention; Fig. 2 is a side schematic view of the first embodiment of the invention; Fig. 3 is a front schematic view of the second embodiment of the invention; Fig. 4 is a side schematic view of the second embodiment of the invention; Fig. 5 is a front schematic view of the third embodiment of the invention; Fig. 6 is a side schematic view of the third embodiment of the invention; Fig. 7 is a front schematic view of the fourth embodiment of the invention; Fig. 8 is a side schematic view of the fourth embodiment of the invention; Fig. 9 is a front schematic view of four-high rolling mill of the prior art; and Fig. 10 is a side schematic view of four-high rolling mill of the prior art. Description of the Preferred Embodiments The following is a detailed description of the present invention. In the above schematic drawings, the positioning modes of the working rolls of all rolling mill are not indicated. The equivalent or similar components in each drawing will be designated by the same reference number. Figs. 9 and 10 are schematic views showing the conventional four-high rolling mills. The two ends of the rolls (working rolls or supporting rolls) are supported on the frame of the mill so that the necks of the roll is subjected to enormous rolling force. During a rolling, the flexural deformation of the roll will occur inevitably due to rolling force such that the rolled plate or strip will be of uneven thickness in its width direction. The thickness of the rolled piece will fail to meet the accuracy requirement and will significantly affect the quality of the rolled piece. Figs. 1 and 2 show the first embodiment of rolling mill with central support of the present invention. The rolling mill includes a mill stand 4 composed of a right piece and a left piece. An upper crossbeam 8 and a lower crossbeam 8' are mounted adjacent to the upper and lower end portions of the mill stand 4. In a window of the mill stand between the upper and lower crossbeams, there are provided with working rolls 12 and 12', bearings 14 and 14', roll seats 16 and 16', and central supporting pads 18 and 18'. The rolled work piece is gripped between the two working rolls 12 and 12'. As can be seen from Figs. 1 and 2, the roll body of the upper working roll 12 is supported on the upper roll seat 16 by means of the upper bearing 14. The bearing 14 is an arc or semi-circular sliding bearing. The supporting pad 18 is provided between the upper roll seat 16 and the upper crossbeam 8. The supporting pad 18 and the sliding bearing 14 are located at the central region of the axis of the working roll body. They should not be located at the neck portion on two ends of the working roll and they should be within the range of working roll's length. The supporting pad may comprise one piece or several pieces. In the embodiment of Figs. 1 and 2, the supporting pad comprises two pieces and the two pieces are symmetrically arranged. A pressing device 6 is disposed at the two ends of the upper crossbeam 8 on the mill stand 4. The pressing device 6 is in contact with the two ends of the upper crossbeam 8 so as to receive the rolling force. In addition, the up and down movement of the pressing device 6 makes the upper crossbeam 8 move up and down inside the window of the mill stand 4 to adjust the clearance between the two rolls. In the embodiment of Figs. 1 and 2, the pressing device is a screwdown device, however, it is obvious to those skilled in the art that the pressing device could be a hydraulic cylinder. The roll body of the lower working roll 12' is supported on the lower roll seat 16' through a lower bearing 14'. The bearing 14' is also an arc or semi-circular sliding bearing. The supporting pads 18' are disposed between the lower roll seat 16' and lower crossbeam 8'. The supporting pad 18' and the sliding bearing 14' are located at the central region of the axis of the working roll body and within the range of the roll body's length. The two ends of the lower crossbeam 8' are supported on the mill stand 4. It is obvious that the clearance of the two rolls (rolling line) can be adjusted by selecting different thickness of the central supporting pad 18'. The adjustment of the clearance of the two rolls (rolling line) can also be realized by means of a hydraulic device or a screwdown device instead of the central supporting pad. In addition, the adjustment of the clearance of the two rolls (rolling line) can also be realized by disposing pads between the lower crossbeam 8' and mill stand 4 or by means of a hydraulic device or a screwdown device. Due to the above-mentioned structure of the rolling mill of the present invention, the flexures of the rolls are effectively reduced. This is because that the rolling mill of the present invention includes the supporting pad members on a region corresponding to the central region of the axis of the working roll body and within the range of the body's length. Therefore, the rolling mill of the present invention can guarantee the proper generating line's profile, i.e. the linearity of the generating line. As a result, the flexural deformation of the working roll basically does not vary with the rolling force. Therefore, the roll's flexural deformation will be significantly reduced so as to reduce the error in thickness of the rolled plate or strip. The rolling mill of the embodiment can be placed upside down, namely, the pressing device may change its acting force to upward while the device may have the same effects. Figs. 3 and 4 show the second embodiment of the rolling mill of the present invention. As can be seen from Fig.3 and 4, this embodiment is an example of four-high rolling mill according to the present invention. The rolling mill has a mill stand 4, a pressing device 6, an upper crossbeam 8 and a lower crossbeam 8'. In a window of the mill stand located between the upper and lower crossbeams, there are provided with working rolls 22 and 22', supporting rolls 23 and 23', bearings 24 and 24', roll seats 26 and 26' and central supporting pads 28 and 28'. The differences between the second embodiment and the first embodiment is in that an additional supporting roll is disposed between the working roll and roll seat while the other structures and the operation mechanism are the same. It is advantageous to dispose an additional middle extracting roll between the working roll and supporting roll, i.e. applying the present invention in an HC mill. Figs. 5 and 6 show the third embodiment of the present invention. As can be seen from the drawings, this embodiment is an example of the tower-like roll system mill. The rolling mill includes a mill stand 4, a pressing device 6, an upper crossbeam 8, and a lower crossbeam 8'. In a window of the mill stand located between the upper and the lower crossbeam, there are provided with working rolls 32 and 32', two upper supporting rolls 33, two lower supporting rolls 33', bearings 34 and 34', roll seats 36 and 36', and central supporting pads 38 and 38'. The invention is not limited to six rolls tower-like roll system mill as shown in the drawings, it is also applicable for use in the system with other numbers of rolls or other structures. In the second and the third embodiment of the present invention, the bearings may be sliding bearings as used in the first embodiment. It is also possible to use rolling bearings instead of the sliding bearings. The rolling bearings can be made by the supporting rolls themselves, forming back-bushing bearing consisting of inner race and outer ring. Figs. 7 and 8 show the fourth embodiment of the rolling mill of the present invention. The rolling mill includes a mill stand 4, a pressing device 6, an upper crossbeam 8, and a lower crossbeam 8'. In the window of the mill stand located between the upper and lower crossbeam, there are provided with upper and lower working rolls 42 and 42', bearings 44 and 44', upper and lower roll seats 46 and 46', and central supporting pads 48' which are located between the lower roll seat 46' and the lower crossbeam 8'. Comparing to the first embodiment, the upper crossbeam 8 of the rolling mill in this embodiment is secured to the mill stand 4. The pressing device 6 is disposed on the upper crossbeam 8 corresponding to the central region of the axis of the working roll body instead of on the mill stand 4 corresponding to the two ends of the upper crossbeam. The upper supporting pads 18 are omitted in this embodiment. The pressing device 6 contact to the upper roll seats directly. It is thus obvious that, the present embodiment transfers the downward action of the pressing device from two ends of the crossbeam to its central portion, which makes the devices have the functions of both the pressing device and the upper supporting pads. In addition, the present embodiment can also apply the roll systems and the roll seats described in the second and the third embodiments which will not be repeatedly described herein. Moreover, in this embodiment, the upper and lower crossbeam 8 and 8' may splice, weld or cast with mill stand 4 and form an integral to achieve the same technical effects. All the rolling mills described in the second, the third and the fourth embodiments can be placed upside down to achieve the same technical effects. The screwdowns used in the second, the third, and the fourth embodiments can also be replaced by hydraulic cylinders. In the second, the third and the fourth embodiments, the transmission of the rolling forces, and the principles and functions of the central portion supporting system or central downward action in the reduction of the flexural deformation of the working rolls are also substantially the same, this will not be repeatedly described herein. Compared with the prior art, the rolling mill of the present invention has the following advantages: Since the central supports or pressing devices of the rolling mill of the present invention are disposed on a region corresponding to the central region of the axis of the working roll body, which provide central supporting system onto the working rolls within the range of the working roll body's length. Therefore, the rolling mill of present invention can guarantee the proper generating line's profile, as a result, the flexural deformation of the working roll basically does not vary with the rolling force fluctuation so as to result in the reduction of the error in thickness of the rolled plate or strip. The rolling mill of the present invention can simplify the design of the original roll shape (cambering) and the control of the roll shape during rolling. Since the flexural deformation of the working roll of the rolling mill of the present invention basically does not vary with the rolling force fluctuation, in the course of original roll shape (cambering) design, among the various factors such as the roll's flexural deformation, flattening deformation, heat expansion and wear etc., the most important one, i.e., flexural deformation, can be left out of consideration and the heat expansion and wear are slowly changing factors, so that the design of the roll shape and the control of the roll shape during rolling can be greatly simplified. In addition, the "roll pass" formed by the flexural deformation of the two working rolls in a conventional rolling mill is eliminated, thus facilitating the reasonable transverse flow of the metal and being advantageous to roll high-precision plates and strips with wedge-shaped blanks. The phenomenon of the "edge attenuation" of plates and strips is significantly improved. The upper and lower roll assemblies including the roll seats and the roll systems in the first to the fourth embodiments can be combined to each other. The roll assemblies can also be combined to the roll assemblies in the prior art so as to achieve the object of the invention. The rolling mill of the present invention is particularly applicable for use in the reforming of the existing two-high rolling mill, four-high rolling mill and HC mill, which can be done by replacing the roll systems in the former rolling mills. The invention is not limited to cold rolling mill, but to hot rolling mills for producing hot rolled plates and strips. Although the preferred embodiments of the invention have been described, those skilled in the art could make various modifications to the invention without going beyond the scope of the attached claims of the invention.

Claims: A rolling mill for rolling plate or strip comprising a mill stand (4), an upper crossbeam and a lower crossbeam (8, 8'), a pressing device (6), roll seats (16, 16'; 26, 26'; 36, 36'), upper roll system (12; 22, 23; 32, 33), and lower roll system (12'; 22', 23'; 32', 33'), wherein said upper and lower crossbeam are mounted on the upper and lower end of the mill stand (4) respectively, said pressing device (6) being mounted on the mill stand (4) corresponding to the two ends of the crossbeam and being capable of moving at least one of the upper and lower crossbeams for adjusting the magnitude of the clearance between the two rolls, the upper and the lower roll system and at least one of the roll seats being disposed between the upper and lower crossbeams, characterized by supporting pads (18, 18'; 28, 28'; 38, 38') being disposed between the roll seats and the upper and the lower crossbeams, bearings (14, 14'; 24, 24'; 34, 34') being disposed between the roll systems and the roll seats, and said supporting pads and said bearings being positioned to align to the central portion of the roll systems within the range of the rolls' length. A rolling mill as set forth in claim 1, wherein upper and lower roll systems and upper and lower roll seats are disposed between upper and lower crossbeam. A rolling mill as set forth in claim 1 or claim 2, wherein said bearings are arc-shaped sliding bearings. A rolling mill as set forth in claim 3, wherein said upper roll system is composed of one working roll (12), said sliding bearing (14) is disposed between the working roll (12) and roll seat (16). A rolling mill as set forth in claim 3 or claim 4, wherein said lower roll system is composed of one working roll (12'), said sliding bearing (14') is disposed between the working roll (12') and roll seat (16'). A rolling mill as set forth in claim 3, wherein said upper roll system is composed of one working roll (22) and one supporting roll (23), and said sliding bearing (24) is disposed between the supporting roll (23) and roll seat (26). A rolling mill as set forth in claim 3 or 6, wherein said lower roll system is composed of one working roll (22') and one supporting roll (23'), and said sliding bearing (24') is disposed between the supporting roll (23') and roll seat (26'). A rolling mill as set forth in claim 3, wherein said upper roll system is composed of one working roll (32) and at least two supporting rolls (33), said sliding bearing (34) is disposed between the supporting roll (33) and the roll seat (36). A rolling mill as set forth in claim 3 or 8, wherein said lower roll system is composed of one working roll (32') and at least two supporting rolls (33'), said sliding bearing (34') is disposed between the supporting roll (33') and the roll seat (36'). A rolling mill as set forth in claim 1, wherein said upper roll system is composed of one working roll (22, 32) and at least one supporting roll (23, 33), said supporting roll comprises a rolling bearing which is composed of an inner race and an outer ring. A rolling mill as set forth in claim 1 or 10, wherein said lower roll system is composed of one working roll (22', 32') and at least one supporting roll (23', 33'), said supporting roll is a rolling bearing which is composed of an inner race and an outer ring. A rolling mill as set forth in any one of claims 1 to 11, wherein one of the upper and lower crossbeams is secured on the mill stand (4), and another one can move up and down under the actions of the pressing devices at its two ends. A rolling mill as set forth in any one of claims 1 to 11, wherein the upper and the lower crossbeams are capable of moving up and down under the actions of the pressing devices at their two ends. A rolling mill as set forth in any one of the preceding claims, wherein bearings are provided between the upper roll system and the upper roll seat and between the lower roll system and the lower roll seat. A rolling mill for rolling plate or strip comprising a mill stand (4), an upper crossbeam (8) and a lower crossbeam (8'), a pressing device (6), roll seats (46, 46'), an upper roll system (42) and a lower roll system (42'), wherein said upper and lower crossbeam are secured on an upper end and a lower end of the mill stand (4) respectively, at least one roll seat and upper and lower roll system are provided between the upper and the lower crossbeam, and said pressing device (6) is provided on the central portion of the at least one of said upper and lower crossbeams, the pressing device is capable of moving the roll seats (46, 46') , which is in contact with the pressing device, up and down for adjusting the clearance between two rolls, characterized in that bearings (44, 44') are provided between the roll seats and the upper and the lower roll systems, and said bearings are located to align to the central portion of the roll systems within the range of rolls' length. A rolling mill as set forth in claim 15, wherein the upper and lower roll systems and the upper and lower roll seats are provided between the upper and lower crossbeams. A rolling mill as set forth in claim 15 or 16, wherein said bearings are arc-sliding bearings (44, 44'). A rolling mill as set forth in claim 17, wherein said upper roll system is composed of one working roll (42), said sliding bearing (44) is disposed between the working roll (42) and roll seat (46). A rolling mill as set forth in claim 17 or 18, wherein said lower roll system is composed of one working roll (42'), said sliding bearing (44') is disposed between the working roll (42') and roll seat (46'). A rolling mill as set forth in claim 17, wherein said upper roll system is composed of one working roll and at least one supporting roll, said sliding bearing is disposed between the supporting roll and the roll seat. A rolling mill as set forth in claim 17 or 20, wherein said lower roll system is composed of one working roll and at least one supporting roll, said sliding bearing is disposed between the supporting roll and the roll seat. A rolling mill as set forth in claim 16, wherein said upper roll system is composed of one working roll and at least one supporting roll, said supporting roll is a rolling bearing which is composed of an inner race and an outer ring. A rolling mill as set forth in claim 16 or 22, wherein said lower roll system is composed of one working roll and at least one supporting roll, said supporting roll is a rolling bearing which is composed of an inner race and an outer ring. A rolling mill as set forth in any one of claims 15 to 23, wherein said pressing devices are provided at the central portions of said upper and lower crossbeam. A rolling mill as set forth in any one of claims 15 to 23, wherein said pressing device (6) is only provided at the central portion of said upper crossbeam, the supporting pad (48') is provided between said lower crossbeam and roll seat, and the supporting pad is located to align to the central portion of said roll system within the range of rolls' length.

Inventors: ZHAO LINZHEN, ZHENG HONGZHUAN, ZHAO, LINZHEN, ZHENG, HONGZHUAN
Applicants: ZHAO LINZHEN, ZHENG HONGZHUAN, ZHAO, LINZHEN, ZHENG, HONGZHUAN
Application year: 1997
Main classification: B21B13
IPC codes: B21B31, B21B13