Strip shape control system and method for rolling strip material under laterally varying tensile stress

Abstract

To provide a plate shape closed loop control system and method for solving the problem that the application range of a plate shape control means is narrow, the plate shape control capability is insufficient at a high level, and the adjustment control of local tensile stress causes interference between plate shape measurement and coiling stress.SOLUTION: A strip shape closed loop control system is provided that includes a multi-roll rolling mill having a plurality of rolls for rolling strip material under a laterally varying tensile stress. The multi-roll rolling mill is used for rolling a strip material, and an uncoiler and a coiler are provided at both ends of the rolling mill for uncoiling and coiling the strip material. The multi-roll rolling mill utilizes the functions of inclined rolls, bending roll force, channelling roll (roll type), roll segment cooling, backup roll segment adjustment, transverse section tensile stress adjustment and the like to control the sheet shape of the strip. An axial tensile stress variable roll and a strip shape meter are provided on the traveling path of the strip material for controlling and detecting the strip shape of the strip material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of strip shape control, and more particularly to a system and method for closed-loop strip shape control for rolling strip material under tensile stress that varies in the transverse direction. [Background technology]

[0002] Strip materials are widely used in all areas of the national economy and people's lives, and are extremely important basic materials. Strip shape (straightness) is an important indicator for evaluating the quality of strip materials. High-quality, high-performance strip materials, such as steel sheets for home appliances, automotive steel sheets, tin-plated steel sheets, and silicon steel strips, are becoming increasingly hard and thin-walled, resulting in increasingly severe problems with increasingly complex strip shapes, which pose a difficult challenge affecting the quality of precision, high-strength strip materials and foils. How to efficiently control the complex, highly dimensional shape of precision, high-strength strip materials and foils is an important and challenging issue in research into the control of precision strip and foil shape.

[0003] Conventional strip shape control methods mainly include roll-based bending rolls, roll-based channeling rolls, tilt rolls, segment cooling, and backup roll segment adjustment. However, these strip shape control methods have limited scope of operation and cannot meet actual needs. Therefore, a segmented inflatable bladder support method has been used to establish the structure, connection, and assembly of an axial tensile stress variable roll, which can change the tensile stress in the transverse direction of the strip material and the axial tensile stress of the roll, perpendicular to the rolling direction. However, adjusting the sectional tensile stress in the transverse direction of the strip material not only significantly affects the measurement accuracy of the strip shape meter, but may also interfere with the stability between the frames and the running offset phenomenon. Therefore, how to modify the main structure of the tensile stress control system to integrate the axial tensile stress variable roll with a conventional cold rolling strip shape closed-loop control system and how to adjust the axial tensile stress variable roll under different configuration conditions are key factors in determining the efficiency of controlling rolled strip shape under transversely varying tensile stress of the strip material and are also important aspects for promoting the development and application of strip shape control technology under transversely varying tensile stress of the strip material. Summary of the Invention

[0004] In order to solve the drawbacks and deficiencies of the prior art, a system and method for closed-loop control of strip shape for rolling strip material under tensile stress that varies in the transverse direction is provided, which can solve the problems of the conventional strip shape control means having a narrow application range, lacking high-dimensional strip shape control ability, and the adjustment control of local tensile stress causing interference with strip shape measurement and winding stress.

[0005] To achieve the objectives of the present invention, a strip shape closed-loop control system is provided, which includes a multi-roll rolling mill having multiple rolls for rolling strip material under tensile stress that varies in the transverse direction. The multi-roll rolling mill is used for rolling strip material. An unwinder and a winder are installed at both ends of the multi-roll rolling mill, respectively, for unwinding and winding the strip material. The multi-roll rolling mill controls the strip shape of the strip material using functions such as tilt rolls, bending roll force, channeling rolls (roll types), roll segment cooling, backup roll segment adjustment, and transverse section tensile stress adjustment. A variable axial tensile stress roll and a strip shape meter are installed in the strip material's traveling path, for controlling and detecting the strip shape, and a restraining guide S roll is installed in the strip material's traveling path, for separating the tensile stress of the strip material.

[0006] As a further improvement of the above technical solution, the above multi-roll rolling mill may be a single-frame cold rolling mill, and an unwinder and a winder are respectively installed on both the front and rear sides of the running path of the strip material in the single-frame cold rolling mill, the above axial tensile stress variable roll is installed between the single-frame cold rolling mill and the winder, and is used to adjust the strip shape by adjusting the distribution of the local longitudinal tensile stress of the strip material, the above strip shape meter is installed between the unwinder and the single-frame cold rolling mill, and is used to detect the strip shape of the strip material, and the above restraining guide S roll is installed between the axial tensile stress variable roll and the winder, and is used to separate the tensile stress of the strip material.

[0007] As a further improvement of the above technical solution, the above multi-roll rolling mill may be a single-frame cold rolling mill, and an unwinder and a take-up machine are respectively installed on both sides of the running path of the strip material in the single-frame cold rolling mill, the above axial tensile stress variable roll is installed between the single-frame cold rolling mill and the take-up machine, and is used to adjust the strip shape by adjusting the distribution of the local longitudinal tensile stress of the strip material, the above strip shape meter is installed between the axial tensile stress variable roll and the take-up machine, and is used to detect the strip shape of the strip material, and the above restraining guide S roll is installed between the axial tensile stress variable roll and the strip shape meter, and is used to separate the tensile stress of the strip material.

[0008] As a further improvement of the above technical solution, the above multi-roll rolling mill may be a single-frame cold rolling mill, and an unwinder and a winder are respectively installed on the front and rear sides of the running path of the strip material in the single-frame cold rolling mill, and the above axial tensile stress variable roll may be installed between the single-frame cold rolling mill and the winder, and used to adjust the strip shape by adjusting the distribution of local longitudinal tensile stress of the strip material. One of the above strip shape meters may be installed between the unwinder and the single-frame cold rolling mill, and another of the above strip shape meters may be installed between the axial tensile stress variable roll and the winder, and used to detect the strip shape of the strip material, and the above restraining guide S roll may be installed between the axial tensile stress variable roll and another strip shape meter, and used to separate the tensile stress of the strip material.

[0009] As a further improvement of the above technical solution, the multi-roll rolling mill may be a single-frame cold rolling mill, and an unwinder and a winder are installed on both the front and rear sides of the running path of the strip material in the single-frame cold rolling mill, respectively, and the axial tensile stress variable rolls may be installed on both the front and rear sides of the running path of the strip material in the single-frame cold rolling mill, respectively, to adjust the strip shape by adjusting the local longitudinal tensile stress distribution of the strip material. The two strip shape meters may be installed between the unwinder and the axial tensile stress variable roll at the front of the single-frame cold rolling mill, and between the winder and the axial tensile stress variable roll at the rear of the single-frame cold rolling mill, respectively, to detect the strip shape of the strip material. The restraint guide S rolls may be installed between the axial tensile stress variable roll at the front of the single-frame cold rolling mill and the strip shape meter, and between the axial tensile stress variable roll at the rear of the single-frame cold rolling mill and the strip shape meter, respectively, to separate the tensile stress on the strip material.

[0010] As a further improvement of the above technical solution, the multi-roll rolling mill may be a multi-frame cold rolling mill with a multi-frame structure, and an unwinder and a winder may be installed at both the front and rear sides of the travel path of the strip material in the multi-frame cold rolling mill, and an i-th frame axial tensile stress variable roll may be installed at the rear of each i-th frame cold rolling mill of the multi-frame cold rolling mill, which is used to adjust the strip shape by adjusting the local longitudinal tensile stress distribution of the strip material. The strip shape meter may be installed between the end frame axial tensile stress variable roll and the winder, and used to detect the strip shape of the strip material. The restraining guide S roll may be installed between the end frame axial tensile stress variable roll and the strip shape meter, and used to separate the tensile stress of the strip material.

[0011] As a further improvement of the above technical solution, the above multi-roll rolling mill may be a multi-frame cold rolling mill with multiple frames, and an unwinder and a winder are respectively installed on both the front and rear sides of the traveling path of the strip material in the multi-frame cold rolling mill, and an i-th frame axial tensile stress variable roll is installed correspondingly on the rear side of each of the i-th frame cold rolling mills of the multi-frame cold rolling mill, which is used to adjust the strip shape by adjusting the distribution of local longitudinal tensile stress of the strip material. One of the above strip shape meters may be installed between the first frame cold rolling mill and the unwinder, and the other of the above strip shape meters may be installed between the end frame axial tensile stress variable roll and the winder, and used to detect the strip shape of the strip material.

[0012] As a further improvement of the above technical solution, the multi-roll rolling mill is a multi-frame hot rolling mill, and a strip shape meter and a winder are installed in sequence at the outlet of the multi-frame hot rolling mill, the strip shape meter being a non-contact type, and the material at the inlet of the multi-frame hot rolling mill may be supplied from an upstream roughing hot rolling mill. An i-th frame axial tensile stress variable roll may be installed correspondingly at the rear of each i-th frame hot rolling mill in the multi-frame hot rolling mill, and used to adjust the strip shape by adjusting the distribution of local longitudinal tensile stress of the strip material. The strip shape meter may be installed between the end frame axial tensile stress variable roll and the winder, and used to detect the strip shape of the strip material, and the restraining guide S roll may be installed between the axial tensile stress variable roll and the strip shape meter, and used to separate the tensile stress of the strip material.

[0013] As a further improvement of the technical solution, a guide roll may be installed in the travel path of the strip material so that the strip material is in close contact with the axial tensile stress variable roll and the strip shape meter.

[0014] The method for the plate shape closed-loop control system to perform plate shape closed-loop control is as follows: Step 1: Using a plate shape meter, periodic sampling measurements are performed to measure the distribution of the longitudinal residual stress σy inside the strip material, and the difference between the target residual stress and the actually measured longitudinal residual stress is calculated, and this difference is used as the deviation for plate shape control. Step 2: Plate shape mode identification is performed, and the plate shape control deviation is decomposed into 1st to 4th order and other high-order control components. Step 3: Calculate the strip shape control adjustment amount for the axial tensile stress variable roll. Using the influence matrix method or strip shape control effect coefficient method, calculate the adjustment amount vector for the tilt roll, bending roll force, channeling roll (roll type), roll segment cooling, backup roll segment adjustment, and transverse section tensile stress adjustment according to the strip shape deviation discrete vector, and perform automated control. Here, the transverse section tensile stress adjustment control object is the axial tensile stress variable roll, and adjust the voltage or current of the hydraulic or pneumatic system solenoid valve or servo valve to further control the pressure in each passage of the bladder, ultimately affecting the change in local tensile stress of the strip material section. Step 4: Steps 1 to 3 are repeated, strip shape value sampling is cyclically performed, strip shape deviation is calculated, strip shape mode identification is performed, the adjustment amount of the strip material is controlled, and the strip shape is adjusted.

[0015] The beneficial effects of the present invention are as follows: Compared with the prior art, the system and method for closed-loop control of strip shape for rolling strip material under variable transverse tensile stress provided by the present invention applies a variable axial tensile stress roll to the closed-loop control system of strip shape, confirms the configuration and integration method of the rolling technology capable of varying the transverse tensile stress of strip material with the conventional closed-loop control system of strip shape, clarifies the means for varying the axial tensile stress and the method for separating the strip shape detection and winding tension stress in the conventional strip shape control, and provides a solution for the popularization and application of the rolling technology capable of varying the transverse tensile stress. The present invention proposes a new method and configuration for closed-loop control of strip shape capable of varying the transverse tensile stress, effectively solving the problems of the conventional strip shape control means, such as narrow application range, insufficient high-level strip shape control ability, and interference between strip shape measurement and winding stress caused by adjusting local tensile stress. The rolling technology capable of varying the transverse tensile stress is advantageous in fully utilizing the effect of controlling the complex and high-dimensional plate shape of high-quality strip and foil materials, and can effectively promote the application and implementation of the rolling technology capable of varying the transverse tensile stress in the plate shape control of strip materials. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram of the principle of the integrated plate shape closed-loop control system utilizing the axial tensile stress variable roll in the present invention. [Figure 2] 1 is a schematic diagram showing the configuration and operation of a plate shape closed-loop control system involving an axial tensile stress variable roll according to the present invention. FIG. [Figure 3] FIG. 1 is a block diagram of the plate shape negative feedback closed loop control principle in the present invention. [Figure 4] FIG. 1 is a block diagram of the plate shape feedforward control principle in the present invention. [Figure 5] 1 is a schematic diagram 1 of the layout when the multi-roll rolling mill in the present invention is a single-frame cold rolling mill. [Figure 6] 2 is a schematic diagram 2 of the layout when the multi-roll rolling mill in the present invention is a single-frame cold rolling mill. [Figure 7] 3 is a schematic diagram 3 of the layout when the multi-roll rolling mill in the present invention is a single-frame cold rolling mill. [Figure 8] 4 is a schematic diagram 4 showing the layout when the multi-roll rolling mill in the present invention is a single-frame cold rolling mill. [Figure 9] 5 is a schematic diagram 5 showing the layout when the multi-roll rolling mill in the present invention is a single-frame cold rolling mill. [Figure 10] 6 is a schematic diagram 6 showing the layout when the multi-roll rolling mill in the present invention is a single-frame cold rolling mill. [Figure 11] 7 is a schematic diagram 7 showing the layout when the multi-roll rolling mill in the present invention is a single-frame cold rolling mill. [Figure 12] 1 is a schematic diagram 1 of the layout when the multi-roll rolling mill in the present invention is a multi-frame cold rolling mill. [Figure 13] 2 is a schematic diagram 2 of the layout when the multi-roll rolling mill in the present invention is a multi-frame cold rolling mill. [Figure 14] 1 is a schematic diagram 1 of the layout when the multi-roll rolling mill in the present invention is a multi-frame hot rolling mill. DETAILED DESCRIPTION OF THE INVENTION

[0017] Specific embodiments of the present invention will be described in more detail below in conjunction with the accompanying drawings. As shown in Figures 1 to 4, the present invention provides a strip shape closed-loop control system for rolling strip material under tensile stress that varies in the transverse direction, which includes a multi-roll rolling mill and is used to roll strip material. An unwinder and a winder are installed at both ends of the multi-roll rolling mill, respectively, for unwinding and winding the strip material. The multi-roll rolling mill controls the strip shape of the strip material by using tilt rolls, bending roll force, channeling rolls (roll types), roll segment cooling, backup roll segment adjustment, and transverse section tensile stress adjustment. An axial tensile stress variable roll and a strip shape meter are installed in the strip material's traveling path, for controlling and detecting the strip shape. A restraining guide S roll is installed in the strip material's traveling path, for separating the tensile stress of the strip material.

[0018] As shown in Figures 5 and 6, the multi-roll rolling mill is a single-frame cold rolling mill, and an unwinder and a winder are installed on both the front and rear sides of the strip material's running path in the single-frame cold rolling mill, respectively. The axial tensile stress variable roll is installed between the single-frame cold rolling mill and the winder and is used to adjust the strip shape by adjusting the local longitudinal tensile stress distribution of the strip material. The strip shape meter is installed between the unwinder and the single-frame cold rolling mill and is used to detect the strip shape of the strip material. The restraint guide S roll is installed between the axial tensile stress variable roll and the winder and is used to separate the tensile stress of the strip material.

[0019] As shown in Figures 7 and 8, the multi-roll rolling mill is a single-frame cold rolling mill, and an unwinder and a winder are installed on both the front and rear sides of the strip material's running path in the single-frame cold rolling mill, respectively. The axial tensile stress variable roll is installed between the single-frame cold rolling mill and the winder and is used to adjust the strip shape by adjusting the local longitudinal tensile stress distribution of the strip material. The strip shape meter is installed between the axial tensile stress variable roll and the winder and is used to detect the strip shape of the strip material. The restraint guide S roll is installed between the axial tensile stress variable roll and the strip shape meter and is used to separate the tensile stress of the strip material.

[0020] 9-10, the multi-roll rolling mill is a single-frame cold rolling mill, and an unwinder and a winder are installed on both the front and rear sides of the running path of the strip material in the single-frame cold rolling mill, respectively, and the axial tensile stress variable roll is installed between the single-frame cold rolling mill and the winder and is used to adjust the strip shape by adjusting the local longitudinal tensile stress distribution of the strip material. One of the strip shape meters is installed between the unwinder and the single-frame cold rolling mill, and the other strip shape meter is installed between the axial tensile stress variable roll and the winder and is used to detect the strip shape of the strip material. The restraint guide S roll is installed between the axial tensile stress variable roll and the other strip shape meter and is used to separate the tensile stress of the strip material.

[0021] As shown in Figure 11, the multi-roll rolling mill is a single-frame cold rolling mill, and an unwinder and a rewinder are installed on both the front and rear sides of the strip material's running path in the single-frame cold rolling mill, respectively. The axial tensile stress variable rolls are installed on both the front and rear sides of the strip material's running path in the single-frame cold rolling mill, respectively, and are used to adjust the strip shape by adjusting the local longitudinal tensile stress distribution of the strip material. The two strip shape meters are installed between the unwinder and the axial tensile stress variable roll at the front of the single-frame cold rolling mill, and between the rewinder and the axial tensile stress variable roll at the rear of the single-frame cold rolling mill, respectively, and are used to detect the strip shape of the strip material. The restraint guide S rolls are installed between the axial tensile stress variable roll at the front of the single-frame cold rolling mill and the strip shape meter, and between the axial tensile stress variable roll at the rear of the single-frame cold rolling mill and the strip shape meter, respectively, and are used to isolate the tensile stress on the strip material.

[0022] As shown in Figure 12, the multi-roll rolling mill is a multi-frame cold rolling mill, and an unwinder and a rewinder are installed on both the front and rear sides of the strip material's running path in the multi-frame cold rolling mill. An i-th frame axial tensile stress variable roll is installed correspondingly on the rear side of each i-th frame cold rolling mill in the multi-frame cold rolling mill, and is used to adjust the strip shape by adjusting the local longitudinal tensile stress distribution of the strip material. The strip shape meter is installed between the end frame axial tensile stress variable roll and the rewinder, and is used to detect the strip shape of the strip material. The restraint guide S roll is installed between the end frame axial tensile stress variable roll and the strip shape meter, and is used to separate the tensile stress of the strip material.

[0023] 13, the multi-roll rolling mill is a multi-frame cold rolling mill, and an unwinder and a winder are respectively installed on the front and rear sides of the running path of the strip material in the multi-frame cold rolling mill, and an i-th frame axial tensile stress variable roll is installed correspondingly on the rear side of each of the i-th frame cold rolling mills of the multi-frame cold rolling mill, which is used to adjust the strip shape by adjusting the distribution of local longitudinal tensile stress of the strip material. One of the strip shape meters is installed between the first frame cold rolling mill and the unwinder, and the other is installed between the end frame axial tensile stress variable roll and the winder, and is used to detect the strip shape of the strip material.

[0024] As shown in Figure 14, the multi-roll rolling mill is a multi-frame hot rolling mill, and a strip shape meter and a winder are installed at the outlet of the multi-frame hot rolling mill, in order. The strip shape meter is a non-contact type strip shape meter. The material at the inlet of the multi-frame hot rolling mill is supplied from the upstream roughing hot rolling mill. The rear of the i-th frame hot rolling mill in the multi-frame hot rolling mill is correspondingly installed with the i-th frame axial tensile stress variable roll, which is used to adjust the strip shape by adjusting the local longitudinal tensile stress distribution of the strip material. The strip shape meter is installed between the end frame axial tensile stress variable roll and the winder and is used to detect the strip shape of the strip material. The restraining guide S roll is installed between the axial tensile stress variable roll and the strip shape meter and is used to separate the tensile stress of the strip material.

[0025] At the same time, guide rolls are installed on the travel path of the strip material so that the strip material is in close contact with the axial tensile stress variable roll and the strip shape meter.

[0026] The specific steps of the method for the plate shape closed-loop control system to perform plate shape closed-loop control are as follows: Step 1: Using a plate shape meter, periodic sampling measurements are performed to measure the distribution of the longitudinal residual stress σy inside the strip material, and the difference between the target residual stress and the actually measured longitudinal residual stress is calculated, and this difference is used as the deviation for plate shape control. Step 2: Plate shape mode identification is performed, and the plate shape control deviation is decomposed into 1st to 4th order and other high-order control components. Step 3: Calculate the strip shape control adjustment amount for the axial tensile stress variable roll. Using the influence matrix method or strip shape control effect coefficient method, calculate the adjustment amount vector for the tilt roll, bending roll force, channeling roll (roll type), roll segment cooling, backup roll segment adjustment, and transverse section tensile stress adjustment according to the strip shape deviation discrete vector, and perform automated control. Here, the object of transverse section tensile stress adjustment control is the axial tensile stress variable roll, and by adjusting and controlling the voltage or current of the hydraulic or pneumatic system solenoid valve or servo valve, further control the pressure in each bladder passage, ultimately affecting the change in local tensile stress of the strip material section. Step 4: Steps 1 to 3 are repeated, strip shape value sampling is cyclically performed, strip shape deviation is calculated, strip shape mode identification is performed, the adjustment amount of the strip material is controlled, and the strip shape is adjusted.

[0027] The above embodiments are not limited to the technical solutions of the above embodiments themselves, and the embodiments can be combined with each other to form new embodiments. The above embodiments only illustrate the technical solutions of the present invention, but do not limit it, and any modifications or substitutions that do not depart from the spirit and scope of the present invention should be included in the scope of the technical solutions of the present invention.

Claims

1. A strip shape closed-loop control system for rolling a strip material under a tensile stress that varies in a transverse direction of the strip material perpendicular to the rolling direction, the system comprising: a multi-roll rolling mill having a plurality of rolls and used to roll the strip material; The multi-roll rolling mill is provided at both ends with a rewinder and a winder, respectively, for rewinding and winding the strip material; The multi-roll rolling mill controls the strip shape of the strip material by adjusting the tilt roll, bending roll force, channeling roll (roll type), roll segment cooling, backup roll segment adjustment, and transverse section tensile stress; The strip shape closed-loop control system for rolling strip material under tensile stress that changes in the transverse direction is characterized in that an axial tensile stress variable roll that can change the axial tensile stress and a strip shape meter are provided on the running path of the strip material, and are used to control and detect the strip shape of the strip material, and a restraining guide S roll is provided on the running path of the strip material, and is used to separate the tensile stress of the strip material.

2. 2. The system for closed-loop control of strip shape under transversely varying tensile stress for rolling strip material according to claim 1, wherein the multi-roll rolling mill is a single-frame cold rolling mill, and an unwinder and a winder are respectively installed on both sides of the running path of the strip material in the single-frame cold rolling mill, the axial tensile stress variable roll is installed between the single-frame cold rolling mill and the winder, and is used to adjust the strip shape by adjusting the distribution of the local longitudinal tensile stress of the strip material, the strip shape meter is installed between the unwinder and the single-frame cold rolling mill, and is used to detect the strip shape of the strip material, and the restraining guide S roll is installed between the axial tensile stress variable roll and the winder, and is used to separate the tensile stress of the strip material.

3. 2. The strip shape closed-loop control system for rolling strip material under transversely varying tensile stress according to claim 1, wherein the multi-roll rolling mill is a single-frame cold rolling mill, and an unwinder and a winder are respectively installed on the front and rear sides of the running path of the strip material in the single-frame cold rolling mill, the axial tensile stress variable roll is installed between the single-frame cold rolling mill and the winder, and is used to adjust the strip shape by adjusting the distribution of the local longitudinal tensile stress of the strip material, the strip shape meter is installed between the axial tensile stress variable roll and the winder, and is used to detect the strip shape of the strip material, and the restraining guide S roll is installed between the axial tensile stress variable roll and the strip shape meter, and is used to separate the tensile stress of the strip material.

4. 2. The system for closed-loop control of strip shape for rolling strip material under transversely varying tensile stress according to claim 1, wherein the multi-roll rolling mill is a single-frame cold rolling mill, and an unwinder and a take-up machine are respectively installed on the front and rear sides of the running path of the strip material in the single-frame cold rolling mill, the axial tensile stress variable roll is installed between the single-frame cold rolling mill and the take-up machine, and is used to adjust the strip shape by adjusting the distribution of the local longitudinal tensile stress of the strip material, one of the strip shape meters is installed between the unwinder and the single-frame cold rolling mill, and the other strip shape meter is installed between the axial tensile stress variable roll and the take-up machine, and is used to detect the strip shape of the strip material, and the restraining guide S roll is installed between the axial tensile stress variable roll and another strip shape meter, and is used to separate the tensile stress of the strip material.

5. 2. The system for closed-loop control of strip shape under transversely varying tensile stress according to claim 1, wherein the multi-roll rolling mill is a single-frame cold rolling mill, and an unwinder and a take-up machine are installed on both sides of the running path of the strip material in the single-frame cold rolling mill, respectively; the variable axial tensile stress rolls are installed on both sides of the running path of the strip material in the single-frame cold rolling mill, respectively, for adjusting the distribution of local longitudinal tensile stress of the strip material to adjust the strip shape; the two shape meters are installed between the unwinder and the variable axial tensile stress roll at the front of the single-frame cold rolling mill, and between the take-up machine and the variable axial tensile stress roll at the rear of the single-frame cold rolling mill, respectively, for detecting the strip shape of the strip material; and the restraint guide S rolls are installed between the variable axial tensile stress roll at the front of the single-frame cold rolling mill and the shape meter, and between the variable axial tensile stress roll at the rear of the single-frame cold rolling mill and the shape meter, respectively, for separating the tensile stress on the strip material.

6. 2. The closed-loop control system for strip shape under transversely varying tensile stress according to claim 1, wherein the multi-roll rolling mill is a multi-frame cold rolling mill with multiple frames, and an unwinder and a winder are respectively installed on both the front and rear sides of the traveling path of the strip material in the multi-frame cold rolling mill, and an i-th frame axial tensile stress variable roll is installed correspondingly on the rear side of each i-th frame cold rolling mill of the multi-frame cold rolling mill, for adjusting the strip shape by adjusting the distribution of local longitudinal tensile stress of the strip material, the strip shape meter is installed between the end frame axial tensile stress variable roll and the winder, for detecting the strip shape of the strip material, and the restraining guide S roll is installed between the end frame axial tensile stress variable roll and the strip shape meter, for separating the tensile stress of the strip material.

7. 2. The closed-loop control system for strip shape under transversely varying tensile stress according to claim 1, wherein the multi-roll rolling mill is a multi-frame cold rolling mill, and an unwinder and a winder are respectively installed on the front and rear sides of the traveling path of the strip material in the multi-frame cold rolling mill, and an i-th frame axial tensile stress variable roll is installed correspondingly on the rear side of the i-th frame cold rolling mill of the multi-frame cold rolling mill, for adjusting the strip shape by adjusting the distribution of local longitudinal tensile stress of the strip material, and one of the strip shape meters is installed between the first frame cold rolling mill and the unwinder, and the other of the strip shape meters is installed between the end frame axial tensile stress variable roll and the winder, for detecting the strip shape of the strip material.

8. 2. The closed-loop control system for strip shape under transversely varying tensile stress according to claim 1, wherein the multi-roll rolling mill is a multi-frame hot rolling mill with a multi-frame structure, and a strip shape meter and a winder are sequentially installed at the outlet of the multi-frame hot rolling mill, the strip shape meter being a non-contact type strip shape meter, the material at the inlet of the multi-frame hot rolling mill is supplied from an upstream roughing hot rolling mill, and an i-th frame axial tensile stress variable roll is installed correspondingly at the rear of each of the i-th frame hot rolling mills in the multi-frame hot rolling mill, for adjusting the strip shape by adjusting the distribution of local longitudinal tensile stress of the strip material, the strip shape meter is installed between the end frame axial tensile stress variable roll and the winder, for detecting the strip shape of the strip material, and the restraining guide S roll is installed between the axial tensile stress variable roll and the strip shape meter, for separating the tensile stress of the strip material.

9. 2. The system for closed-loop control of strip shape for rolling strip material under tensile stress that varies in the transverse direction according to claim 1, wherein guide rolls are installed in the traveling path of the strip material so that the strip material is in close contact with the axial tensile stress variable roll and the strip shape meter.

10. A method for performing plate shape closed-loop control using the plate shape closed-loop control system according to any one of claims 2 to 9, comprising: Step 1: Using a plate shape meter to periodically perform sampling measurements to measure the distribution of longitudinal residual stress σy inside the strip material, and calculate the difference between the target residual stress and the actually measured longitudinal residual stress, and use this difference as the deviation of plate shape control; Step 2: Identify the plate shape mode and decompose the plate shape control deviation into 1st to 4th order and other high-order control components; Step 3: calculate the strip shape control adjustment amount for the axial tensile stress variable roll, adopt the influence matrix method or the strip shape control effect coefficient method, calculate the adjustment amount vector of the tilt roll, bending roll force, channeling roll (roll type), roll segment cooling, backup roll segment adjustment, and transverse section tensile stress adjustment according to the strip shape deviation discrete vector, and carry out automatic control, where the transverse section tensile stress adjustment control object is the axial tensile stress variable roll, and adjust the voltage or current of the hydraulic or pneumatic system solenoid valve or servo valve to further control the pressure in each passage of the bladder, which ultimately affects the change of the local tensile stress of the strip material section; Step 4: A method for performing closed-loop control of plate shape, comprising repeating steps 1 to 3, cyclically sampling plate shape values, calculating plate shape deviations, identifying plate shape modes, controlling the adjustment amount of the strip plate material, and adjusting the plate shape.

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