Loop variable tension control method in hot continuous rolling accelerated rolling process

Abstract

The invention discloses a control method for loop variable tension in the hot continuous rolling speed-up rolling process, and belongs to the technical field of metallurgy automation control. The method comprises the steps that after a pyrometer at an outlet of a finishing mill group detects strip steel, delay time is delayed, and pyrometer data are sampled and actually measured and locked; determining the acceleration of the tail rack of the finishing mill and the set threading speed of each rack of the finishing mill group, and calculating the acceleration of each rack of the finishing mill; determining set tension and set angles of loops among the racks; after a finish rolling outlet pyrometer value is locked and delayed for time, calculating a set tension value of a dynamic correction loop according to data such as actually-measured loop angle values between racks and the like; after amplitude limiting protection is conducted on the dynamically-corrected loop set tension value, the dynamically-corrected loop set tension value is compensated to the initial loop set tension; and after the finishing mill group throws steel, the tension compensation value of the dynamic correction loop of the strip steel is calculated to be zero. According to the invention, the problem of width narrowing caused by accelerated rolling and finish rolling temperature rise in hot continuous rolling is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical automation control, and in particular relates to a method for controlling the variable tension of a looper in a hot rolling speed-up rolling process. Background Art

[0002] In the field of metal rolling, the looper between the stands of the finishing mill plays the role of adjusting the flow rate between the stands. Through its tension, the rolling stability and product quality standards are guaranteed. Too large tension can ensure rolling stability, but it is easy to cause the strip to be narrowed; small tension can reduce the phenomenon of strip narrowing, but it is easy to reduce rolling stability. Therefore, the reasonable adjustment of the looper tension between the stands is a topic worthy of in-depth research.

[0003] At present, there is no control technology for the variable tension of the looper in the process of speed-up rolling of the hot rolling finishing mill. However, there are several control methods for the variable tension of the looper between the stands: 1. (Announcement No.: CN103464472A, title: Variable tension control method for improving the uniformity of the full length width of thin hot-rolled stainless steel), the patent application proposes a calculation method for adjusting the looper tension only according to the final rolling temperature, and the control method will be adjusted to a constant tension when the preset conditions are met during the control process. 2. (Announcement No.: CN113020285B, title: A looper variable gain control method and device), the patent application proposes a variable gain control method based on the strip rolling specifications and strip tracking applied to continuous casting and rolling equipment to ensure rolling stability and strip quality. 3. (Announcement No.: CN112122356B, title: A control method for reducing the width margin of the strip), the patent application proposes a variable tension setting method combined with the load distribution coefficient of each stand of the finishing rolling, and the goal of reducing the width margin of the strip is achieved by automatically adding tension to the looper in actual control.

[0004] However, due to the increased temperature change of the finishing mill during the speed-up process, the conventional feedback control method that generally combines the final rolling temperature and the strip width deviation cannot solve the above problems well; in summary, there is currently a lack of variable tension control methods for the looper during the speed-up process of the hot rolling finishing mill in the field of metal rolling. The set tension of the looper between frames can be effectively corrected through automated control means and combined with the feedforward control idea, thereby improving the stability of the strip during the rolling process and the strip width quality.

[0005] To this end, we have introduced a method for controlling the variable tension of the loop during the hot rolling speed increase process. Summary of the invention

[0006] The object of the present invention is to provide a method for controlling the variable tension of a looper during the hot rolling process, so as to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for controlling the variable tension of a looper during a hot rolling process, comprising: S1, Delay time T after the pyrometer at the outlet of the finishing mill detects the strip de , sampling measured pyrometer data t aem , lock; S2. Specify the final stand acceleration of the finishing mill and the threading speed S of each stand of the finishing mill. FX , calculate the acceleration of each stand of the finishing mill; S3, set the tension TE of the loops between the frames FX-1 , set angle AN FX-1 ; S4, delay time T after the pyrometer value at the finishing rolling exit is locked av , according to the measured data such as the angle value of the looper between each frame, the dynamic correction looper setting tension value is calculated; S5, after performing limit protection on the tension value set by the dynamic correction looper, compensate it to the initial looper tension setting; S6. After the finishing mill has finished rolling the steel, the dynamic correction looper tension compensation value calculated for this strip will be reset to zero.

[0008] Preferably, the step S1 includes: after the pyrometer at the outlet of the finishing mill detects the strip, a delay time T de , sampling measured pyrometer data t aem , lock; The delay time T after the pyrometer at the outlet of the finishing mill detects the strip de , sample and lock the pyrometer value, where the pyrometer detects the delay time T after the strip de The given experience value ranges from 10 to 500, in ms.

[0009] Preferably, the pyrometer at the outlet of the finishing mill detects the strip and samples and locks the pyrometer value after a delay time; Among them, the calculation formula of the pyrometer lock value is: Among them, t ave It indicates the temperature lock value of the strip head measured by the pyrometer, in °C; t aem It indicates the real-time temperature of the strip measured by the pyrometer, in °C; TA indicates the controller execution cycle; N indicates the number of sampling points of the strip outlet temperature measured by the pyrometer.

[0010] Preferably, the controller executes a cycle TA and the number of sampling points N of the strip outlet temperature measured by the pyrometer; The empirical value range of the controller execution cycle TA is 1 to 32, with the unit of ms; the number of sampling points N of the strip outlet temperature measured by the pyrometer is N, and the empirical value range of N is 10 to 100.

[0011] Preferably, the step S2 includes: clarifying the acceleration of the last stand of the finishing mill and setting the threading speed S of each stand of the finishing mill group. FX , calculate the acceleration of each stand of the finishing mill; According to the acceleration of the final stand and each stand of the finishing mill, the threading speed S is set FX , calculate the acceleration a of the subsequent racks except the last rack FX The calculation formula is: a Fx-1 = S FX-1 / S FX × a FX Among them, a FX , S FX The X in the figure represents the number of finishing mills, and the acceleration of the final stand represents a F8 , a Fx-1 Indicates the front frame acceleration in m / s 2 ; S Fx-1 Indicates the front frame setting threading speed, in m / s; S Fx Indicates the rear frame threading speed, in m / s; a Fx Indicates the acceleration of the rear frame in m / s 2 .

[0012] Preferably, the step S3 includes: clarifying the setting tension TE of the loops between the racks FX-1 , set angle AN FX-1 ; Among them, it should be noted that TE FX-1 , AN FX-1 The X in the figure indicates the number of finishing mills, the setting tension of the looper before the last stand is TE7, and the setting angle of the looper between each stand is AN. FX-1 , unit is °, set tension TE of the loop between each frame FX-1 , unit is kN.

[0013] Preferably, the step S4 includes: a delay time T after the high temperature gauge value at the finishing rolling exit is locked. av , based on the measured data such as the angle values ​​of the loops between each frame, the dynamic correction loop setting tension value is calculated.

[0014] Preferably, the delay time T after the pyrometer value at the finishing rolling exit is locked av， Among them, the delay time T after the pyrometer detects the strip av The empirical value range is 10 to 500, in ms; According to the measured data such as the angle value of the looper between each frame, the formula for calculating the dynamic correction looper set tension value is: Among them, T dn-1 Indicates the tension compensation value set by the dynamic correction loop, in kN; t ave It indicates the temperature lock value of the strip head measured by the pyrometer, in °C; t aem It indicates the real-time temperature of the strip measured by the pyrometer, in °C; a FX Indicates the acceleration of the rear frame in m / s 2 TE FX-1 Indicates the set tension of the loops between the racks, in kN; Kp FX-1 Indicates the compensation coefficient of the variable tension of the front loop of each frame; AN FX-1 Indicates the setting angle of the loops between the racks, in degrees; AN FaX-1 It indicates the actual angle of the loops between the racks, in degrees; TA indicates the execution cycle of the controller.

[0015] The variable tension compensation coefficient Kp of the front loop of each frame FX-1 And the controller execution cycle TA, in which the tension compensation coefficient Kp of the front loop of each rack FX-1 , the empirical value range is 0.01~0.2; the empirical value range of the controller execution period TA is 1~32, in ms.

[0016] Preferably, the S5 includes: after performing amplitude limiting protection on the tension value set by the dynamic correction looper, compensating it to the initial looper tension setting value, wherein the amplitude limiting protection is performed on the tension value set by the dynamic correction looper; Among them, set the upper limit value Tu of the tension compensation value of the dynamic correction loop dn-1 The empirical value range is 1 to 10, and the unit is kN; set the lower limit of the tension compensation value Tl of the dynamic correction loop dn-1 , its value is given by experience, the value range is -1 to -10, and the unit is kN; The calculation formula for compensating the dynamic correction looper setting tension compensation value to the initial looper setting tension is: TEA Fx-1 = T dn-1 +TE Fx-1 Among them, TEA FX-1 It indicates the set tension after the loop compensation between the frames, in kN; T dn-1 Indicates the tension compensation value set by the dynamic correction loop, in kN; TE FX-1 Indicates the set tension of the loops between the frames, in kN.

[0017] Preferably, the S6 includes: after the finishing mill group throws the steel, the dynamic correction looper tension compensation value calculated for the strip is cleared.

[0018] Compared with the prior art, the technical effects and advantages of the present invention are as follows: the method for controlling the variable tension of the looper during the hot rolling speed increase process is (1) Delay time T after the pyrometer at the outlet of the finishing mill detects the strip de , sampling measured pyrometer data t aem , lock it; clarify the acceleration of the last stand of the finishing mill and the setting of the threading speed S of each stand of the finishing mill FX , calculate the acceleration of each stand of the finishing mill; clarify the setting tension TE of the looper between each stand FX-1 , set angle AN FX-1 ; Delay time T after the pyrometer value at the finishing rolling exit is locked av , calculate the dynamic correction looper set tension value based on the measured data such as the looper angle value between each frame; after the dynamic correction looper set tension value is limited and protected, it is compensated to the initial looper set tension; after the finishing mill throws the steel, the dynamic correction looper tension compensation value calculated for this strip is cleared to zero.

[0019] (2) The control method of the present invention is simple and easy. First, the pyrometer data at the outlet of the finishing mill is locked, and then the speed, acceleration, looper setting tension, angle and other parameters of each frame of the finishing mill are combined to calculate the dynamic correction looper setting tension value. This can more accurately match the actual working conditions in the rolling process, achieve accurate control of the looper tension, and avoid the influence of abnormal tension on the strip quality. It is beneficial to solve the problem of width narrowing caused by speed increase and final rolling temperature increase in hot rolling. The tension can be appropriately increased in response to the temperature reduction to improve the rolling stability, and the width deviation is used as a partial adjustment basis, which has a positive significance for improving the width quality of the strip. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A flowchart of the execution of a method for controlling variable tension of a looper during a hot rolling speed increase process provided by an embodiment of the present invention. DETAILED DESCRIPTION The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] See also Figure 1The present invention provides a technical solution: a method for controlling the variable tension of a looper during the hot rolling process, wherein the delay time T after the pyrometer at the outlet of the finishing mill detects the strip de , sampling measured pyrometer data t aem , lock it; clarify the acceleration of the last stand of the finishing mill and the setting of the threading speed S of each stand of the finishing mill FX , calculate the acceleration of each stand of the finishing mill; clarify the setting tension TE of the looper between each stand FX-1 , set angle AN FX-1 ; Delay time T after the pyrometer value at the finishing rolling exit is locked av , calculate the dynamic correction looper set tension value based on the measured data such as the looper angle value between each frame; after the dynamic correction looper set tension value is limited and protected, it is compensated to the initial looper set tension; after the finishing mill throws the steel, the dynamic correction looper tension compensation value calculated for this strip is cleared to zero.

[0022] Specifically, the execution process of this method is as follows Figure 1 As shown, the following steps are included: S1, the delay time T after the pyrometer at the outlet of the finishing mill detects the strip de , sampling measured pyrometer data t aem , lock; Among them, the delay time T after the pyrometer detects the strip de , is an empirical value, ranging from [10,500], in ms.

[0023] Among them, the calculation formula of the pyrometer lock value is: Among them, t ave It indicates the temperature lock value of the strip head measured by the pyrometer, in °C; t aem It indicates the real-time temperature of the strip measured by the pyrometer, in °C; TA indicates the controller execution cycle, which is given by experience, in the range of [1,32], in ms; N indicates the number of sampling points of the strip outlet temperature measured by the pyrometer, which is given by experience, in the range of [10,100].

[0024] S2, specify the final stand acceleration of the finishing mill and the threading speed S of each stand of the finishing mill group FX , calculate the acceleration of each stand of the finishing mill; Among them, the threading speed S is set according to the acceleration of the last stand and each stand of the finishing mill. FX Calculate the acceleration a of the rear racks except the last rack FX The calculation formula is: a Fx-1 = S FX-1 / SFX × a FX Among them, it should be noted that a FX , S FX The X in the figure represents the number of finishing mills. If the number of finishing mills is 8, then the acceleration of the last stand is a. F8 . , a Fx-1 Indicates the front frame acceleration in m / s 2 ; S Fx-1 Indicates the front frame setting threading speed, in m / s; S Fx Indicates the rear frame threading speed, in m / s; a Fx Indicates the acceleration of the rear frame in m / s 2 .

[0025] S3, clearly set the tension TE of the loops between each frame FX-1 , set angle AN FX-1 ; Among them, it should be noted that TE FX-1 , AN FX-1 The X in the figure represents the number of finishing mills. For example, if the number of finishing mills is 8, the tension setting of the looper before the last stand is TE7. The tension setting of the looper between each stand is TE FX-1 , unit is kN, the angle AN of the loop setting between each frame FX-1 , unit is °.

[0026] S4, the pyrometer value at the finishing rolling exit is locked for a period of time T av , according to the measured data such as the angle value of the looper between each frame, the dynamic correction looper setting tension value is calculated; Among them, the delay time T after the pyrometer detects the strip av , is an empirical value, ranging from [10,500], in ms.

[0027] Among them, according to the measured data such as the angle value of the looper between each frame, the calculation formula for the dynamic correction looper setting tension value is: Among them, T dn-1 Indicates the tension compensation value set by the dynamic correction loop, in kN; t ave It indicates the temperature lock value of the strip head measured by the pyrometer, in °C; t aem It indicates the real-time temperature of the strip measured by the pyrometer, in °C; a FX Indicates the acceleration of the rear frame in m / s 2 TE FX-1 Indicates the set tension of the loops between the racks, in kN; Kp FX-1Indicates the variable tension compensation coefficient of the front loop of each frame, which is given by experience and has a value range of [0.01,0.2]; AN FX-1 Indicates the setting angle of the loops between the racks, in degrees; AN FaX-1 It represents the actual angle of the loops between the racks, in degrees; TA represents the controller execution cycle, which is given by experience, ranging from [1,32], in ms.

[0028] S5, after performing limit protection on the dynamic correction looper set tension value, it is compensated to the initial looper set tension; The upper limit value Tu of the tension compensation value set by the dynamic correction loop is set. dn-1 , its value is given by experience, the value range is [1,10], and the unit is kN; set the lower limit value Tl of the tension compensation value of the dynamic correction loop dn-1 , its value is given by experience, the value range is [-1,-10], and the unit is kN.

[0029] The calculation formula for compensating the dynamic correction looper setting tension compensation value to the initial looper setting tension is: TEA Fx-1 = T dn-1 +TE Fx-1 Among them, TEA FX-1 It indicates the set tension after the loop compensation between the frames, in kN; T dn-1 Indicates the tension compensation value set by the dynamic correction loop, in kN; TE FX-1 Indicates the set tension of the loops between the frames, in kN.

[0030] S6, after the finishing mill has finished rolling the steel, the dynamic correction looper tension compensation value calculated for this strip is reset to zero.

[0031] The implementation process of the method of the present invention is described below in conjunction with specific application examples.

[0032] In this application example, taking the number of finishing mill stands as 8 as an example, the operation is performed as follows: (1) After the pyrometer at the outlet of the finishing mill detects the delay time of the strip, the measured pyrometer data is sampled and locked. The lock value calculation formula is: The relevant parameter assignments and calculation results are shown in Table 1 below: Table 1 (2) Determine the acceleration of the last stand of the finishing mill and the set threading speed of each stand of the finishing mill, and calculate the acceleration of each stand of the finishing mill. The calculation formula is: a Fx-1 = S FX-1 / S FX × a FX The calculation results are shown in Table 2 below: Table 2 It should be noted that, because the looper is located between the front and rear racks, 7 loopers are used for 8 racks, that is, the data of rack No. 1 does not need to be used, and the same applies to the following; (3) Clarify the setting tension and setting angle of the loops between each frame, and the relevant parameter assignments are shown in Table 3 below: Table 3 (4) After the pyrometer value at the finishing rolling exit is locked, a delay of a period of time T is set. av , where T av Assign a value of 200, and calculate the dynamic correction looper set tension value based on the measured looper angle values ​​between each frame and other data. The calculation formula is: The relevant parameter assignments and calculation results are shown in Table 4 below: Table 4 (5) After the dynamic correction looper set tension value is limited and protected, it is compensated to the initial looper set tension, where the calculation formula is: TEA Fx-1 = T dn-1 +TE Fx-1 The relevant parameter assignments and calculation results are shown in Table 5 below: Table 5 (6) After the finishing mill has finished rolling the strip, the dynamic correction looper tension compensation value calculated for this strip will be reset to zero.

[0033] Through the above application examples, it can be found that the control method of the variable tension of the looper during the hot rolling speed-up rolling process of the present invention can perform real-time dynamic correction of the looper tension during the strip speed-up rolling process in actual production, which is more convenient and flexible, and has a good use effect on the width narrowing problem caused by the speed-up rolling and the increase of the final rolling temperature in the hot rolling, and has positive significance for improving the rolling stability and the width quality of the strip.

[0034] In summary, the control method of this embodiment is to delay for a period of time after the pyrometer at the outlet of the finishing mill detects the strip, sample the measured pyrometer data and lock it, clarify the acceleration of the last frame of the finishing mill, set the threading speed of each frame of the finishing mill, calculate the acceleration of each frame of the finishing mill, and the set tension and angle of the looper between each frame, wait for a period of time after the pyrometer value at the outlet of the finishing mill is locked, calculate the dynamic correction looper set tension value according to the measured looper angle value between each frame and other data, and compensate it to the initial looper set tension after the dynamic correction looper set tension value is limited and protected, and then clear the calculated dynamic correction looper tension compensation value of this strip after the finishing mill throws the steel. It is beneficial to solve the problem of width narrowing caused by speed increase and final rolling temperature increase in hot rolling, and has positive significance for improving rolling stability and strip width quality.

[0035] In addition, it should be noted that the present invention can be provided as a method, an apparatus or a computer program product. Therefore, the embodiments of the present invention can take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the embodiments of the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code.

[0036] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0037] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, so that a series of operation steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable terminal device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0038] It should also be noted that, in this article, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the variable tension of a looper during hot rolling at an increasing speed, characterized in that: include: S1, Delay time T after the pyrometer at the outlet of the finishing mill detects the strip de , sampling measured pyrometer data t aem , lock; S2. Specify the final stand acceleration of the finishing mill and the threading speed S of each stand of the finishing mill. FX , calculate the acceleration of each stand of the finishing mill; S3, set the tension TE of the loops between the frames FX-1 , set angle AN FX-1 ; S4, delay time T after the pyrometer value at the finishing rolling exit is locked av , according to the measured data such as the angle value of the looper between each frame, the dynamic correction looper setting tension value is calculated; S5, after performing limit protection on the tension value set by the dynamic correction looper, compensate it to the initial looper tension setting; S6. After the finishing mill has finished rolling the steel, the dynamic correction looper tension compensation value calculated for this strip will be reset to zero.

2. The method for controlling the variable tension of the looper during the hot rolling process according to claim 1, characterized in that: The S1 includes: the delay time T after the pyrometer at the outlet of the finishing mill detects the strip de , sampling measured pyrometer data t aem , lock; The delay time T after the pyrometer at the outlet of the finishing mill detects the strip de , sample and lock the pyrometer value, where the pyrometer detects the delay time T after the strip de The given experience value ranges from 10 to 500, in ms.

3. The method for controlling the variable tension of the looper during the hot rolling speed increase process according to claim 2, characterized in that: After the pyrometer at the outlet of the finishing mill detects the strip, a delay is made for a period of time to sample and lock the pyrometer value; Among them, the calculation formula of the pyrometer lock value is: Among them, t ave It indicates the temperature lock value of the strip head measured by the pyrometer, in °C; t aem It indicates the real-time temperature of the strip measured by the pyrometer, in °C; TA indicates the controller execution cycle; N indicates the number of sampling points of the strip outlet temperature measured by the pyrometer.

4. The method for controlling the variable tension of the looper during the hot rolling process according to claim 3, characterized in that: The controller executes a cycle TA and the number of sampling points N of the strip outlet temperature measured by the pyrometer; The empirical value range of the controller execution cycle TA is 1 to 32, with the unit of ms; the number of sampling points N of the strip outlet temperature measured by the pyrometer is N, and the empirical value range of N is 10 to 100.

5. The method for controlling the variable tension of the looper during the hot rolling process according to claim 1, characterized in that: The S2 includes: clarifying the acceleration of the last stand of the finishing mill, setting the threading speed S of each stand of the finishing mill group FX , calculate the acceleration of each stand of the finishing mill; According to the acceleration of the final stand and each stand of the finishing mill, the threading speed S is set FX , calculate the acceleration a of the subsequent racks except the last rack FX The calculation formula is: a Fx-1 = S FX-1 / S FX × a FX Among them, a FX , S FX The X in the figure represents the number of finishing mills, and the acceleration of the final stand represents a F8 , a Fx-1 Indicates the front frame acceleration in m / s 2 ; S Fx-1 Indicates the front frame setting threading speed, in m / s; S Fx Indicates the rear frame threading speed, in m / s; a Fx Indicates the acceleration of the rear frame in m / s 2 .

6. The method for controlling the variable tension of the looper during the hot rolling process according to claim 1, characterized in that: The step S3 includes: clarifying the setting tension TE of the loops between the frames FX-1 , set angle AN FX-1 ; Among them, it should be noted that TE FX-1 , AN FX-1 The X in the figure indicates the number of finishing mills, the setting tension of the looper before the last stand is TE7, and the setting angle of the looper between each stand is AN. FX-1 , the unit is °, the tension TE of the loop between each frame is set FX-1 , unit is kN.

7. The method for controlling the variable tension of the looper during the hot rolling process according to claim 1, characterized in that: The step S4 includes: the delay time T after the pyrometer value at the finishing rolling exit is locked av , based on the measured data such as the angle values ​​of the loops between each frame, the dynamic correction loop setting tension value is calculated.

8. The method for controlling the variable tension of the looper during the hot rolling process according to claim 1, characterized in that: Delay time T after the pyrometer value at the finishing rolling exit is locked av， Among them, the delay time T after the pyrometer detects the strip av The empirical value range is 10 to 500, in ms; According to the measured data such as the angle value of the looper between each frame, the formula for calculating the dynamic correction looper set tension value is: Among them, T dn-1 Indicates the tension compensation value set by the dynamic correction loop, in kN; t ave It indicates the temperature lock value of the strip head measured by the pyrometer, in °C; t aem It indicates the real-time temperature of the strip measured by the pyrometer, in °C; a FX Indicates the acceleration of the rear frame in m / s 2 TE FX-1 Indicates the set tension of the loops between the racks, in kN; Kp FX-1 Indicates the compensation coefficient of the variable tension of the front loop of each frame; AN FX-1 Indicates the setting angle of the loops between the racks, in degrees; AN FaX-1 It indicates the actual angle of the loops between the racks, in degrees; TA indicates the controller execution cycle; The variable tension compensation coefficient Kp of the front loop of each frame FX-1 And the controller execution cycle TA, in which the tension compensation coefficient Kp of the front loop of each rack FX-1 , the empirical value range is 0.01~0.2; the empirical value range of the controller execution period TA is 1~32, in ms.

9. The method for controlling the variable tension of the looper during the hot rolling process according to claim 1, characterized in that: The step S5 includes: after performing amplitude limiting protection on the tension value set by the dynamic correction looper, compensating it to the initial tension set by the looper, wherein the amplitude limiting protection is performed on the tension value set by the dynamic correction looper; Among them, set the upper limit value Tu of the tension compensation value of the dynamic correction loop dn-1 The empirical value range is 1 to 10, and the unit is kN; set the lower limit of the tension compensation value Tl of the dynamic correction loop dn-1 , its value is given by experience, the value range is -1 to -10, and the unit is kN; The calculation formula for compensating the dynamic correction looper setting tension compensation value to the initial looper setting tension is: TEA Fx-1 = T dn-1 + THE Fx-1 Among them, TEA FX-1 It indicates the set tension after the loop compensation between the frames, in kN; T dn-1 Indicates the tension compensation value set by the dynamic correction loop, in kN; TE FX-1 Indicates the set tension of the loops between the frames, in kN.

10. The method for controlling the variable tension of the looper during the hot rolling process according to claim 1, characterized in that: The step S6 includes: after the finishing mill group throws the steel, the dynamic correction looper tension compensation value calculated for the strip is reset to zero.

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