A method for controlling the elongation of a tension leveller

Abstract

The application discloses a method for switching the elongation of a strip steel weld seam when passing through a tension leveler, which comprises the following steps: establishing a tension limiting model with the cross-sectional area of the strip steel as the independent variable; adopting an interval automatic switching control mode for the elongation of the tension leveler equipment; and constructing an elongation switching interval model with the thickness of the strip steel as the independent variable. The application can improve the stability of the operation of the unit, reduce the labor intensity of the operator, and avoid the strip steel weld seam breaking accident when passing through the tension leveler equipment.

Description

Technical Field

[0001] This invention relates to cold rolling hot-dip galvanizing mill equipment, and more specifically, to a method for controlling the elongation rate switching of strip welds when they pass through a tension leveling machine. Background Technology

[0002] The tension leveling machine in the leveling section of the hot-dip galvanizing unit consists of, in sequence, tension roller No. 7, straightening unit No. 1, straightening unit No. 2, anti-C-curving unit, anti-L-curving unit, and tension roller No. 8. The tension leveling machine's control function is to correct strip shape defects. Strip shape defects result from uneven stress caused by differences in particle structure within the strip. The tension leveling machine uses the tension roller to provide a certain tension, thereby altering the stress distribution in the strip and ultimately improving its shape. However, traditional tension leveling machine control methods have the following problems in practical use:

[0003] 1) Because the strip weld over-tension straightening machine does not have a tension limiting model with the strip cross-sectional area as the independent variable, the strip may break due to improper tension setting after the thin soft steel weld is over-tensioned, which affects the stable operation of the unit to a certain extent.

[0004] 2) In the elongation control mode, the elongation switching point of the strip weld over-tension straightening machine is 1 meter in front of the straightening machine. This causes excessive tension of the straightening machine to act on the subsequent strip when some strips are transitioning. If it exceeds the maximum yield strength of the strip, it will cause a strip breakage accident.

[0005] Existing patent applications, such as patent publication number CN101332469A, disclose a method for controlling a strip leveling machine. This method sets deviation conditions for the front and rear strips and their corresponding control modes for the strip leveling machine. When the deviation of the front and rear strips meets the deviation conditions, the corresponding control mode of the strip leveling machine is executed. The control modes of the strip leveling machine include: A: Strip leveling machine not activated; B: Strip leveling machine activated slowly; C: Strip leveling machine activated quickly. The deviation conditions for the strips refer to the deviation in the material of the front and rear strips. Specifically, the deviation conditions refer to the width or thickness deviation of the front and rear strips. This invention can maximize the use of equipment capabilities, providing technical support for improving product quality and production capacity.

[0006] For example, patent publication number CN110067000A discloses a method for controlling the movement of strip welds through a straightening machine and a pickling zone. The method includes: acquiring the position of the strip weld; when the strip weld is a first distance from the front end of the straightening machine, controlling the movement speed of the strip in the straightening machine and pickling zone to be less than or equal to a first set speed; acquiring the position of the strip weld; and when the strip weld is a second distance from the rear end of the pickling zone, controlling the movement speed of the strip in the straightening machine and pickling zone to be greater than or equal to a second set speed. The method for controlling the movement of strip welds through a straightening machine and a pickling zone provided by this invention can prevent poor cleaning of the weld and surrounding areas, as well as scraping or strip breakage during high-speed passage through the pickling tank, thus achieving stable and high-speed production in the pickling process.

[0007] Compared with the above two patented technologies, this invention establishes a tension limiting model for a tension straightening machine with the cross-sectional area of ​​the strip steel as the independent variable. At the same time, the control mode for switching the elongation rate of the strip steel weld seam under tension straightening adopts an automatic interval switching control mode, and the control model with the strip steel thickness as the independent variable is used for the interval size. This meets the process requirements, prevents possible strip breakage accidents in the strip steel weld seam tension straightening machine, and ensures the stable operation of the unit. Summary of the Invention

[0008] In view of the deficiencies in the existing technology, the purpose of this invention is to provide a method for switching control of the elongation rate of strip welds when passing through a tension leveling machine, which can improve the stability of unit operation, reduce the labor intensity of operators, and avoid accidents of strip welds breaking when passing through the tension leveling machine.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for controlling the elongation switching of strip welds when they pass through a tension leveler includes:

[0011] Establish a tension limiting model with the cross-sectional area of ​​the strip as the independent variable;

[0012] The elongation rate of the tension straightening machine adopts an automatic interval switching control mode;

[0013] Construct an elongation switching interval model with the thickness of the strip as the independent variable.

[0014] Preferably, the tension limiting model is established as follows:

[0015] 1) Calculate the tension setting limit of the tension straightening machine;

[0016] 2) Calculate the tension switching slope of the tension straightening machine.

[0017] Preferably, the elongation rate of the tension straightening machine adopts an automatic interval switching control mode as follows:

[0018] 1) Calculate the automatic switching control time point for the elongation rate of the tension straightening machine;

[0019] 2) Calculate the elongation range based on strip thickness as the independent variable.

[0020] Preferably, the tension setting limit is calculated as follows:

[0021] TLV_TEN=TLV_THCIK_C*TLV_WIDTH_C*K1 / 1000 (1)

[0022] In formula (1), TLV_TEN represents the limit calculation value of the tension leveler's set value, in kN; TLV_THCIK_C represents the current strip thickness of the tension leveler, in mm; TLV_WIDTH_C represents the current strip width of the tension leveler, in mm; and K1 represents the unit tension value of the tension leveler, in N / mm. 2 ;

[0023] R_TLV_TEN_MAX=MIN{K2 TLV_TEN} (2)

[0024] In formula (2), R_TLV_TEN_MAX represents the maximum limit value of the tension straightening machine. The minimum value of the two is taken as the maximum limit value of the tension setting of the tension straightening machine, and the unit is KN; K2 represents the maximum capacity value of the tension straightening machine; TLV_TEN represents the limit calculation value of the tension setting value of the tension straightening machine, and the unit is KN.

[0025] Preferably, the tension switching slope is calculated as follows:

[0026] TLV_TEN_RAMP_SET=ABS(TLV_TEN_SET_C-TLV_TEN_SET_N)*R_COM_RAMP_SET_SCAN*K3(3)

[0027] In equation (3), TLV_TEN_RAMP_SET represents the tension switching slope of the tension straightener, in KN / SCAN; TLV_TEN_SET_C represents the current roll tension setting value of the tension straightener, in KN; TLV_TEN_SET_N represents the next roll tension setting value of the tension straightener, in KN; R_COM_RAMP_SET_SCAN represents the scanning time of the leveling machine CPU, in seconds; and K3 represents the tension switching coefficient of the tension straightener.

[0028] Preferably, the automatic elongation switching control time point of the tension straightening machine is calculated as follows:

[0029] K4=R_8ABR1_GEAR*R_8ABR1_RD*R_PAI / R_DRIVE_PLS (4)

[0030] In formula (4), K4 represents the length of the strip corresponding to each pulse, in mm / PLS; R_8ABR1_GEAR represents the gear ratio of the gearbox of the first roller on the eighth set of tensioning rollers; R_8ABR1_RD represents the diameter of the first roller on the eighth set of tensioning rollers, in mm; R_PAI represents pi; R_DRIVE_PLS represents the number of pulses per revolution of the motor of the first roller on the eighth set of tensioning rollers.

[0031]

[0032] In formula (5), TLV_TRK_LEN represents the strip tracking calculation length when the strip weld passes the weld detector, in meters; 8ABR1_RTC represents the number of pulses emitted when the first roller on the eighth tension roller rotates, in the number of pulses.

[0033] TLV_TRK_LEN_A=G_WPD2_TLV_L-K5 (6)

[0034] In equation (6), TLV_TRK_LEN_A represents the length at time A of the automatic elongation switching control of the tension straightener, in meters; G_WPD2_TLV_L represents the length between the weld detector and the tension straightener, in meters; K5 represents the distance between the strip weld and the center of the tension straightener when the strip weld has not passed the tension straightener, in meters.

[0035] TLV_TRK_LEN_B=G_WPD2_TLV_L+k6 (7)

[0036] In equation (7), TLV_TRK_LEN_B represents the length of the automatic elongation switching control B point of the tension straightening machine, in meters; G_WPD2_TLV_L represents the length between the weld detector and the tension straightening machine, in meters; K6 represents the distance between the strip weld and the center of the tension straightening machine after the strip weld passes through the tension straightening machine, in meters.

[0037] Preferably, the elongation range based on strip thickness is calculated as follows:

[0038] K5=K5max-(TLV_THCIK_N-TH_MIN)*(K5max-K5min) / (TH_MAX-TH_MIN) (8)

[0039] In formula (8), K5 represents the distance between the strip weld and the center of the tension leveler before the weld passes through the tension leveler, in meters; K5max represents the maximum length of K5; K5min represents the minimum length of K5; TLV_THCIK_N represents the thickness of the next coil of strip in the tension leveler, in millimeters; TH_MAX represents the maximum thickness of the strip in the tension leveler; TH_MIN represents the minimum thickness of the strip in the tension leveler.

[0040] K6=K6max-(TLV_THCIK_N-TH_MIN)*(K6max-K6min) / (TH_MAX-TH_MIN) (9)

[0041] In formula (9), K6 represents the distance between the strip weld and the center of the tension leveler after passing through the tension leveler, in meters; K6max represents the maximum length of K6; K6min represents the minimum length of K6; TLV_THCIK_N represents the thickness of the next coil of strip steel after passing through the tension leveler, in mm; TH_MAX represents the maximum thickness of the strip steel after passing through the tension leveler; and TH_MIN represents the minimum thickness of the strip steel after passing through the tension leveler.

[0042] Preferably, the different interval control of the elongation switching interval model includes:

[0043] The tension straightener uses elongation control for the current roll and continues to use elongation control for the next roll.

[0044] The tension straightener uses elongation control for the current roll but not for the next roll.

[0045] The tension straightener does not use elongation control for the current roll, but uses elongation control for the next roll.

[0046] Preferably, the tension straightening machine uses elongation control for the current roll and continues to use elongation control for the next roll, specifically as follows:

[0047] The flattening programmable logic controller of the tension straightening machine calculates the automatic switching control point A of the elongation rate of the tension straightening machine according to equations (4), (5), (6) and (8), and automatically switches the elongation rate control of the tension straightening machine to the tension closed-loop control mode. The tension closed-loop control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0048] After the strip weld passes through the tension straightening machine, the flattening programmable logic controller calculates the elongation rate automatic switching control point B of the tension straightening machine according to equations (4), (5), (7) and (9), and automatically switches the tension closed-loop control mode of the tension straightening machine to the elongation rate control mode. The elongation rate control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0049] Preferably, the tension straightening machine uses elongation control for the current roll but not for the next roll, specifically as follows:

[0050] The flattening programmable logic controller of the tension straightening machine calculates the elongation rate automatic switching control point A of the tension straightening machine according to equations (4), (5), (6) and (8), and automatically switches the elongation rate control of the tension straightening machine to the tension closed-loop control mode. The tension closed-loop control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0051] Preferably, the tension straightening machine does not use elongation control for the current roll, but uses elongation control for the next roll, specifically as follows:

[0052] After the strip weld passes through the tension straightening machine, the tension straightening machine flattening programmable logic controller calculates the elongation rate automatic switching control point B of the tension straightening machine according to equations (4), (5), (7) and (9), and automatically switches the tension closed-loop control mode of the tension straightening machine to the elongation rate control mode. The elongation rate control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0053] Preferably, the unit tension value K1 of the tension straightening machine is 80–160 N / mm. 2 ;

[0054] The tension switching coefficient K3 of the tension straightening machine is between 0.1 and 2.

[0055] The value of pi, R_PAI, is 3.14159.

[0056] When the strip weld has not passed through the tension leveling machine, the distance K5 between the weld and the center of the tension leveling machine is 2 to 10 m.

[0057] After the strip weld passes through the tension leveling machine, the distance K6 between the weld and the center of the tension leveling machine is 2 to 10 meters.

[0058] Preferably, the thickness of the strip is 0.25-2.5 mm and the width is 700-1630 mm;

[0059] The running speed of the leveling section of the tension straightening machine is 0–220 m / min.

[0060] The elongation switching control method for strip welds passing through a tension leveler provided by this invention has the following beneficial effects:

[0061] 1) This invention changes the shortcomings of existing tension limiting models that do not construct a tension limiting model with the cross-sectional area of ​​the strip as the independent variable, which leads to strip breakage accidents due to improper tension setting after the weld seam of thin soft steel is over-tensioned. This invention ensures the stable operation of the unit to a certain extent.

[0062] 2) This invention changes the drawback of the existing strip weld over-tension straightening machine equipment where the elongation switching point is 1 meter before the straightening machine, which causes excessive tension of the straightening machine to act on the subsequent strip during the transition of some strips. The automatic switching of the elongation of the straightening machine adopts the interval control mode, which completely avoids the accident of strip breakage in the weld of the straightening machine and ensures the stable operation of the unit.

[0063] 3) This invention is used on the leveling machine of the hot-dip galvanizing unit in the cold rolling mill. In addition to effectively eliminating product defects caused by strip steel roller marks, it can also significantly improve the labor intensity of operators and reduce the roller consumption cost of products. It has the value of being promoted and applied. Detailed Implementation

[0064] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with embodiments.

[0065] This invention provides a method for controlling the elongation switching of strip welds when they pass through a tension leveling machine, comprising:

[0066] By establishing a tension limiting model with the cross-sectional area of ​​the strip as the independent variable, the thin-material soft steel weld seam will not break due to improper tension setting after passing through the leveling machine, thus fundamentally ensuring the stable operation of the unit.

[0067] The elongation rate of the tension leveling machine adopts an automatic interval switching control mode. This control mode takes into account the drawback that excessive tension of the leveling machine may affect the subsequent strip when some strips are transitioning, potentially exceeding the maximum yield strength of the strip. This can effectively avoid strip breakage accidents of the leveling machine.

[0068] A model for switching the elongation rate with strip thickness as the independent variable is constructed to minimize the length of strip defects. Operators no longer need to set the scrap cutting length of the flying shear based on the length of the strip defects, thus reducing the labor intensity of operators.

[0069] The elongation switching control method of the present invention is applicable to strips with a thickness of 0.25 to 2.5 mm and a width of 700 to 1630 mm; the running speed of the leveling section of the tension straightening machine is 0 to 220 m / min.

[0070] The tension limiting model is established as follows:

[0071] 1) Calculate the tension setting limit of the tension straightening machine, as follows:

[0072] TLV_TEN=TLV_THCIK_C*TLV_WIDTH_C*K1 / 1000 (1)

[0073] In equation (1), TLV_TEN represents the limit calculation value of the set value of the tension straightening machine, and the unit is KN;

[0074] TLV_THCIK_C indicates the current strip thickness of the tension leveler, in mm;

[0075] TLV_WIDTH_C represents the current strip width of the tension leveler, in mm;

[0076] K1 represents the unit tension value of the tension leveling machine, in N / mm. 2 The value range is 80~160N / mm 2 In this embodiment, the unit selected is 120N / mm. 2 .

[0077] R_TLV_TEN_MAX=MIN{K2 TLV_TEN} (2)

[0078] In formula (2), R_TLV_TEN_MAX represents the maximum amplitude limit of the tension straightening machine. The minimum value of the two is taken as the maximum amplitude limit of the tension setting of the tension straightening machine, and the unit is KN.

[0079] K2 represents the maximum capacity of the tension straightening machine; in this example, the unit selected is 295KN.

[0080] TLV_TEN represents the limit calculation value of the tension setting value of the tension straightening machine, in kN.

[0081] 2) Calculate the tension switching slope of the tension straightening machine, as follows:

[0082] TLV_TEN_RAMP_SET=ABS(TLV_TEN_SET_C-TLV_TEN_SET_N)*R_COM_RAMP_SET_SCAN*K3(3)

[0083] In equation (3), TLV_TEN_RAMP_SET represents the tension switching slope of the tension straightening machine, with the unit being KN / SCAN;

[0084] TLV_TEN_SET_C represents the current coil tension setting of the tension leveler, in kN;

[0085] TLV_TEN_SET_N represents the tension setting value for the next roll of the tension leveler, in kN.

[0086] R_COM_RAMP_SET_SCAN represents the scanning time of the leveling machine CPU, in seconds. In the example unit, 0.05 seconds is selected.

[0087] K3 represents the tension switching coefficient of the tension straightening machine, with a value range of 0.1 to 2. In the example unit, 0.75 is selected.

[0088] Second, the elongation rate of the tension straightening machine adopts an automatic interval switching control mode as follows:

[0089] 1) Calculate the automatic switching control time point for the elongation rate of the tension straightening machine, as follows:

[0090] K4=R_8ABR1_GEAR*R_8ABR1_RD*R_PAI / R_DRIVE_PLS (4)

[0091] In formula (4), K4 represents the length of the strip corresponding to each pulse, in mm / PLS. In this embodiment, the unit is selected as 0.600361 mm / PLS.

[0092] R_8ABR1_GEAR represents the gear ratio of the gearbox of the first roller on the eighth tension roller. In this embodiment, the unit is selected as 0.03913435.

[0093] R_8ABR1_RD represents the diameter of the first roller on the eighth set of tension rollers, in mm. In this embodiment, the unit is selected as 1250.1 mm.

[0094] R_PAI represents pi, a constant with a value of 3.14159;

[0095] R_DRIVE_PLS represents the number of pulses per revolution of the motor of the first roller on the eighth tension roller. The unit is pulses per revolution. In this embodiment, the unit is selected as 256 pulses per revolution.

[0096]

[0097] In equation (5), TLV_TRK_LEN represents the calculated length of the strip steel when the strip weld passes through the weld detector (WPD), and the unit is m;

[0098] 8ABR1_RTC represents the number of pulses emitted when the first roller on the eighth tension roller rotates, in units of pulses (PLS).

[0099] TLV_TRK_LEN_A=G_WPD2_TLV_L-K5 (6)

[0100] In equation (6), TLV_TRK_LEN_A represents the length of the automatic elongation switching control A of the tension straightening machine at time point A, in meters;

[0101] G_WPD2_TLV_L represents the length between the weld detector (WPD) and the tension straightener, in meters (m), and is a constant; in this embodiment, the unit is selected as 70.35m.

[0102] K5 represents the distance between the strip weld and the center of the tension leveler before it passes through the tension leveler, in meters, with a range of 2 to 10 meters.

[0103] TLV_TRK_LEN_B=G_WPD2_TLV_L+k6 (7)

[0104] In equation (7), TLV_TRK_LEN_B represents the length of the automatic elongation switching control B of the tension straightening machine at time point B, in meters;

[0105] G_WPD2_TLV_L represents the length between the weld detector and the tension straightening machine, in meters, and is a constant; in this embodiment, the unit is selected as 70.35m.

[0106] K6 represents the distance between the strip weld and the center of the tension leveler after passing through the tension leveler, in meters, with a range of 2 to 10 meters.

[0107] 2) Calculate the elongation range based on strip thickness as the independent variable, as follows:

[0108] K5=K5max-(TLV_THCIK_N-TH_MIN)*(K5max-K5min) / (TH_MAX-TH_MIN) (8)

[0109] In formula (8), K5 represents the distance between the strip weld and the center of the tension leveler when the weld has not passed through the tension leveler, in meters, with a range of 2 to 10 meters;

[0110] K5max represents the maximum length of K5, which is 10m in this embodiment.

[0111] K5min represents the minimum length of K5, which is 2m in this embodiment.

[0112] TLV_THCIK_N indicates the thickness of the next coil of strip in the tension leveler, in mm;

[0113] TH_MAX represents the maximum strip thickness of the tension leveler; in this embodiment, the unit is selected as 2.5mm.

[0114] TH_MIN represents the minimum strip thickness of the tension straightening machine; in this embodiment, the unit thickness is selected as 0.25mm.

[0115] K6=K6max-(TLV_THCIK_N-TH_MIN)*(K6max-K6min) / (TH_MAX-TH_MIN) (9)

[0116] In formula (9), K6 represents the distance between the strip weld and the center of the tension leveler after passing through the tension leveler, in meters, with a range of 2 to 10 meters;

[0117] K6max represents the maximum length of K6, which is 10m in this embodiment.

[0118] K6min represents the minimum length of K6, which is 2m in this embodiment.

[0119] TLV_THCIK_N indicates the thickness of the next coil of strip in the tension leveler, in mm;

[0120] TH_MAX represents the maximum strip thickness of the tension leveler; in this embodiment, the unit is selected as 2.5mm.

[0121] TH_MIN represents the minimum strip thickness of the tension straightening machine; in this embodiment, the unit thickness is selected as 0.25mm.

[0122] Third, the different interval controls of the elongation rate switching interval model include:

[0123] The tension straightener uses elongation control for the current roll and continues to use elongation control for the next roll.

[0124] The tension straightener uses elongation control for the current roll but not for the next roll.

[0125] The tension straightener does not use elongation control for the current roll, but uses elongation control for the next roll.

[0126] 1) The tension leveler uses elongation control for the current roll and continues to use elongation control for the next roll, as detailed below:

[0127] The flattening programmable logic controller of the tension straightening machine calculates the elongation rate automatic switching control point A of the tension straightening machine according to equations (4), (5), (6) and (8), and automatically switches the elongation rate control of the tension straightening machine to the tension closed-loop control mode. The tension closed-loop control mode uses the tension set limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0128] After the strip weld passes through the tension straightening machine, the flattening programmable logic controller calculates the elongation rate of the tension straightening machine at time point B according to equations (4), (5), (7) and (9), and automatically switches the tension closed-loop control mode of the tension straightening machine to the elongation rate control mode. The elongation rate control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0129] 2) The tension leveler uses elongation control for the current roll but not for the next roll, as detailed below:

[0130] The flattening programmable logic controller of the tension straightening machine calculates the elongation rate automatic switching control point A of the tension straightening machine according to equations (4), (5), (6) and (8), and automatically switches the elongation rate control of the tension straightening machine to the tension closed-loop control mode. The tension closed-loop control mode uses the tension set limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0131] 3) The tension leveler does not use elongation control for the current roll, but uses elongation control for the next roll, as detailed below:

[0132] After the strip weld passes through the tension straightening machine, the tension straightening machine flattening programmable logic controller calculates the elongation rate of the tension straightening machine at time point B according to equations (4), (5), (7) and (9), and automatically switches the tension closed-loop control mode of the tension straightening machine to the elongation rate control mode. The elongation rate control mode uses the tension set limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0133] Example 1

[0134] In this embodiment 1, the current strip thickness is 2.014 mm, the current strip width is 1090 mm, the current tension setting of the tension leveler is 70 KN, the thickness of the next roll of strip is 1.501 mm, the width of the next roll of strip is 1005 mm, and the tension setting of the next roll of tension leveler is 50 KN.

[0135] The elongation rate of the tension straightening machine is automatically controlled from the current roll to the next roll.

[0136] To improve the stability of unit operation, reduce the labor intensity of operators, and avoid accidents such as strip breakage due to excessive tension in the strip weld leveling machine, this embodiment 1 adopts the following technical solution to achieve the above objectives: 1. This control method establishes a tension limiting model with the strip cross-sectional area as the independent variable. 2. This control method adopts a control mode that automatically switches the elongation range of the tension leveling machine. 3. This control method constructs an elongation switching range model with the strip thickness as the independent variable.

[0137] The applicable strip specifications are: strip thickness of 0.25~2.5mm and width of 700~1630mm; the running speed of the leveling section of the tension straightening machine is 0~220m / min.

[0138] First, the control part of the tension limiting model with the cross-sectional area of ​​the strip steel as the independent variable was established.

[0139] 1) Calculation of tension setting limit for tension straightening machine

[0140] TLV_TEN=TLV_THCIK_C*TLV_WIDTH_C*K1 / 1000 (1)

[0141] TLV_TEN=2.014*1090*120 / 1000=263.4KN

[0142] In formula (1), TLV_TEN: the limit calculation value of the tension setting value of the tension straightening machine, unit: kN;

[0143] TLV_THCIK_C: Current strip thickness of the tension leveler, in mm;

[0144] TLV_WIDTH_C: Current strip width of the tensioning and straightening machine, in mm;

[0145] K1: Unit tension value of the tension leveling machine, in N / mm 2 Preferably, it is 80–160 N / mm 2 The unit has a strength of 120 N / mm. 2 .

[0146] R_TLV_TEN_MAX=MIN{K2 TLV_TEN} (2)

[0147] In formula (2), R_TLV_TEN_MAX: the maximum amplitude limit of the tension straightening machine. The minimum value of the two is taken as the maximum amplitude limit of the tension setting of the tension straightening machine. The unit is KN.

[0148] K2: Maximum capacity of the tension straightening machine; for this unit, it is 295KN.

[0149] TLV_TEN: Calculated limit value of the tension setting value of the tension straightening machine, unit: kN;

[0150] The tension setting limit of the tension straightening machine is 263.4 kN.

[0151] 2) Calculation of tension switching slope of tension straightening machine

[0152] TLV_TEN_RAMP_SET=ABS(TLV_TEN_SET_C-TLV_TEN_SET_N)*R_COM_RAMP_SET_SCAN*K3(3)

[0153] TLV_TEN_RAMP_SET=(70-50)*0.05*0.75=0.75KN / SCAN

[0154] In equation (3), TLV_TEN_RAMP_SET: tension switching slope of the tension straightening machine, unit: KN / SCAN;

[0155] TLV_TEN_SET_C: Current coil tension setting of the tension leveler, unit: kN;

[0156] TLV_TEN_SET_N: Tension setting value for the next roll of tension leveling machine, unit: kN;

[0157] R_COM_RAMP_SET_SCAN: The scanning time of the leveling machine CPU, in seconds; for this unit, it is 0.05 seconds.

[0158] K3: The tension switching coefficient of the tension straightening machine is preferably 0.1 to 2, and 0.75 for this unit.

[0159] Second, the elongation control of the strip weld over-tension straightening machine adopts an automatic interval switching control section.

[0160] 1) Calculation of the automatic switching control time point for the elongation rate of the tension straightening machine

[0161] K4=R_8ABR1_GEAR*R_8ABR1_RD*R_PAI / R_DRIVE_PLS (4)

[0162] K4=0.03913435*1250.1*3.14159 / 256=0.600361mm / PLS

[0163] In formula (4), K4 is the length of the strip corresponding to each pulse, in mm / PLS, and the length of this unit is 0.600361 mm / PLS.

[0164] R_8ABR1_GEAR: The gear ratio of the gearbox of the NO.1 roller of the NO.8A tension roller on the tension leveler. The gear ratio of this unit is 0.03913435.

[0165] R_8ABR1_RD: The diameter of the NO.1 roller of the NO.8A tension roller on the tension leveler, in mm. The diameter of this unit is 1250.1 mm.

[0166] R_PAI: Pi, a constant with a value of 3.14159;

[0167] R_DRIVE_PLS: The number of pulses per revolution of the motor of the NO.1 roller of the NO.8A tension roller on the tension leveler. The unit is pulses / revolution. The unit for this machine is 256 pulses / revolution.

[0168]

[0169] In equation (5), TLV_TRK_LEN is the calculated length of the strip steel when the strip weld passes through the WPD (weld detector), in meters.

[0170] 8ABR1_RTC: The number of pulses generated by the rotation of the NO.1 roller of the NO.8A tension roller on the tension leveler, in units of pulses (PLS).

[0171] TLV_TRK_LEN_A=G_WPD2_TLV_L-K5 (6)

[0172] TLV_TRK_LEN_A=70.35-5.55=64.8m

[0173] In equation (6), TLV_TRK_LEN_A: the length of the tension straightener at time point A, which is the automatic switching control of the elongation rate. The unit is m.

[0174] G_WPD2_TLV_L: The length from the WPD (weld detector) to the tension straightener, in meters, is a constant; for this unit, it is 70.35 meters.

[0175] K5: The length from the strip weld to the center of the tension leveling machine, in meters, preferably 2 to 10 meters.

[0176] TLV_TRK_LEN_B=G_WPD2_TLV_L+K6 (7)

[0177] TLV_TRK_LEN_B=70.35+5.55=75.9m

[0178] In equation (7), TLV_TRK_LEN_B: the length of the tension straightener at time point B, which is the automatic switching control of the elongation rate. The unit is m.

[0179] G_WPD2_TLV_L: The length from the WPD (weld detector) to the tension straightener, in meters, is a constant; for this unit, it is 70.35 meters.

[0180] K6: The length of the strip weld seam from the center of the tension leveling machine, in meters, preferably 2 to 10 meters.

[0181] 2) Calculation of the elongation range based on strip thickness as the independent variable

[0182] K5=K5max-(TLV_THCIK_N-TH_MIN)*(K5max-K5min) / (TH_MAX-TH_MIN) (8)

[0183] K5=10-(1.501-0.25)*(10-2) / (2.5-0.25)=5.55m

[0184] In formula (8), K5 is the length from the strip weld to the center of the tension leveling machine, in meters, preferably 2 to 10 meters.

[0185] K5max: The maximum length from the strip weld to the center of the tension leveler; for this unit, it is 10m.

[0186] K5min: Minimum length from the strip weld seam to the center of the tension leveler; for this unit, it is 2m.

[0187] TLV_THCIK_N: Strip thickness of the next coil after tension leveling, in mm;

[0188] TH_MAX: The maximum strip thickness for the tension leveling machine; for this unit, it is 2.5mm.

[0189] TH_MIN: Minimum strip thickness for the tension straightening machine; for this unit, it is 0.25mm.

[0190] K6=K6max-(TLV_THCIK_N-TH_MIN)*(K6max-K6min) / (TH_MAX-TH_MIN) (9)

[0191] K6=10-(1.501-0.25)*(10-2) / (2.5-0.25)=5.55m

[0192] In formula (9), K6 is the length of the strip weld seam from the center of the tension leveling machine, in meters, preferably 2 to 10 meters.

[0193] K6max: The maximum length of the strip weld seam from the center of the tension leveler; for this unit, it is 10m.

[0194] K6min: Minimum length of the strip weld seam from the center of the tension leveler; for this unit, it is 2m.

[0195] TLV_THCIK_N: Strip thickness of the next coil after tension leveling, in mm;

[0196] TH_MAX: The maximum strip thickness for the tension leveling machine; for this unit, it is 2.5mm.

[0197] TH_MIN: Minimum strip thickness for tension straightening machine; for this unit, it is 0.25mm.

[0198] Third, the elongation switching of the strip weld over-tension straightening machine adopts different range control sections.

[0199] 1) The tension leveling machine uses elongation control for the current roll and the same for the next roll. The flattening programmable logic controller calculates the elongation control time A (64.8m) of the tension leveling machine according to equations (4), (5), (6) and (8). The elongation control of the tension leveling machine is automatically switched to the tension closed-loop control mode. The tension closed-loop control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0200] After the strip weld passes through the tension leveling machine, the flattening programmable logic controller calculates the elongation rate of the tension leveling machine at time point B (75.9m) according to equations (4), (5), (7) and (9). The tension closed-loop control mode of the tension leveling machine is automatically switched to the elongation rate control mode. The elongation rate control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0201] 2) The switching instructions for the tension straightening machine to use elongation control for the current roll and not use elongation control for the next roll are as follows: The flattening programmable logic controller calculates the elongation control time point A of the tension straightening machine according to Equations (4), (5), (6) and (8), and automatically switches the elongation control of the tension straightening machine to the tension closed-loop control mode. The tension closed-loop control mode uses the tension setting limit value calculated by Equation (1) and the tension switching slope calculated by Equation (2) for control.

[0202] 3) The tension leveling machine does not use elongation control for the current roll and uses elongation control for the next roll. After the strip weld passes through the leveling machine, the flattening programmable logic controller calculates the elongation control time point B of the tension leveling machine according to equations (4), (5), (7) and (9). The tension closed-loop control mode of the tension leveling machine is automatically switched to the elongation control mode. The elongation control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0203] Example 2

[0204] In this embodiment 2, the current strip thickness is 1.993mm, the current strip width is 1258mm, the current tension setting of the tension leveler is 105KN, the thickness of the next roll of strip is 2.306mm, the width of the next roll of strip is 1295mm, and the tension setting of the next roll of tension leveler is 115KN.

[0205] The elongation rate of the tension straightening machine is automatically controlled from when the current roll is not used to when the next roll is used.

[0206] To improve the stability of unit operation, reduce the labor intensity of operators, and avoid accidents such as strip breakage due to excessive tension in the strip weld leveling machine, this embodiment 1 adopts the following technical solution to achieve the above objectives: 1. This control method establishes a tension limiting model with the strip cross-sectional area as the independent variable. 2. This control method adopts a control mode that automatically switches the elongation range of the tension leveling machine. 3. This control method constructs an elongation switching range model with the strip thickness as the independent variable.

[0207] The applicable strip specifications are: strip thickness of 0.25~2.5mm and width of 700~1630mm; the running speed of the leveling section of the tension straightening machine is 0~220m / min.

[0208] First, the control part of the tension limiting model with the cross-sectional area of ​​the strip steel as the independent variable was established.

[0209] 1) Calculation of tension setting limit for tension straightening machine

[0210] TLV_TEN=TLV_THCIK_C*TLV_WIDTH_C*K1 / 1000 (1)

[0211] TLV_TEN=1.993*1258*120 / 1000=300.86KN

[0212] In formula (1), TLV_TEN: the limit calculation value of the tension setting value of the tension straightening machine, unit: kN;

[0213] TLV_THCIK_C: Current strip thickness of the tension leveler, in mm;

[0214] TLV_WIDTH_C: Current strip width of the tensioning and straightening machine, in mm;

[0215] K1: Unit tension value of the tension leveling machine, in N / mm 2 Preferably, it is 80–160 N / mm 2 The unit has a strength of 120 N / mm. 2 .

[0216] R_TLV_TEN_MAX=MIN{K2 TLV_TEN} (2)

[0217] In formula (2), R_TLV_TEN_MAX: the maximum amplitude limit of the tension straightening machine. The minimum value of the two is taken as the maximum amplitude limit of the tension setting of the tension straightening machine. The unit is KN.

[0218] K2: Maximum capacity of the tension straightening machine; for this unit, it is 295KN.

[0219] TLV_TEN: Calculated limit value of the tension setting value of the tension straightening machine, unit: kN;

[0220] The tension setting limit of the tension straightening machine is 395 kN.

[0221] 2) Calculation of tension switching slope of tension straightening machine

[0222] TLV_TEN_RAMP_SET=ABS(TLV_TEN_SET_C-TLV_TEN_SET_N)*R_COM_RAMP_SET_SCAN*K3(3)

[0223] TLV_TEN_RAMP_SET=(115-105)*0.05*0.75=0.375KN / SCAN

[0224] In equation (3), TLV_TEN_RAMP_SET: tension switching slope of the tension straightening machine, unit: KN / SCAN;

[0225] TLV_TEN_SET_C: Current coil tension setting of the tension leveler, unit: kN;

[0226] TLV_TEN_SET_N: Tension setting value for the next roll of tension leveling machine, unit: kN;

[0227] R_COM_RAMP_SET_SCAN: The scanning time of the leveling machine CPU, in seconds; for this unit, it is 0.05 seconds.

[0228] K3: The tension switching coefficient of the tension straightening machine is preferably 0.1 to 2, and 0.75 for this unit.

[0229] Second, the elongation control of the strip weld over-tension straightening machine adopts an automatic interval switching control section.

[0230] 1) Calculation of the automatic switching control time point for the elongation rate of the tension straightening machine

[0231] K4=R_8ABR1_GEAR*R_8ABR1_RD*R_PAI / R_DRIVE_PLS (4)

[0232] K4=0.03913435*1250.1*3.14159 / 256=0.600361mm / PLS

[0233] In formula (4), K4 is the length of the strip corresponding to each pulse, in mm / PLS, and the length of this unit is 0.600361 mm / PLS.

[0234] R_8ABR1_GEAR: The gear ratio of the gearbox of the NO.1 roller of the NO.8A tension roller on the tension leveler. The gear ratio of this unit is 0.03913435.

[0235] R_8ABR1_RD: The diameter of the NO.1 roller of the NO.8A tension roller on the tension leveler, in mm. The diameter of this unit is 1250.1 mm.

[0236] R_PAI: Pi, a constant with a value of 3.14159;

[0237] R_DRIVE_PLS: The number of pulses per revolution of the motor of the NO.1 roller of the NO.8A tension roller on the tension leveler. The unit is pulses / revolution. The unit for this machine is 256 pulses / revolution.

[0238]

[0239] In equation (5), TLV_TRK_LEN is the calculated length of the strip steel when the strip weld passes through the WPD (weld detector), in meters.

[0240] 8ABR1_RTC: The number of pulses generated by the rotation of the NO.1 roller of the NO.8A tension roller on the tension leveler, in units of pulses (PLS).

[0241] TLV_TRK_LEN_A=G_WPD2_TLV_L-K5 (6)

[0242] TLV_TRK_LEN_A=70.35-5.55=64.8m

[0243] In equation (6), TLV_TRK_LEN_A: the length of the tension straightener at time point A, which is the automatic switching control of the elongation rate. The unit is m.

[0244] G_WPD2_TLV_L: The length from the WPD (weld detector) to the tension straightener, in meters, is a constant; for this unit, it is 70.35 meters.

[0245] K5: The length from the strip weld to the center of the tension leveling machine, in meters, preferably 2 to 10 meters.

[0246] TLV_TRK_LEN_B=G_WPD2_TLV_L+K6 (7)

[0247] TLV_TRK_LEN_B=70.35+2.69=73.04m

[0248] In equation (7), TLV_TRK_LEN_B: the length of the tension straightener at time point B, which is the automatic switching control of the elongation rate. The unit is m.

[0249] G_WPD2_TLV_L: The length from the WPD (weld detector) to the tension straightener, in meters, is a constant; for this unit, it is 70.35 meters.

[0250] K6: The length of the strip weld seam from the center of the tension leveling machine, in meters, preferably 2 to 10 meters.

[0251] 2) Calculation of the elongation range based on strip thickness as the independent variable

[0252] K5=K5max-(TLV_THCIK_N-TH_MIN)*(K5max-K5min) / (TH_MAX-TH_MIN) (8)

[0253] K5=10-(1.501-0.25)*(10-2) / (2.5-0.25)=5.55m

[0254] In formula (8), K5 is the length from the strip weld to the center of the tension leveling machine, in meters, preferably 2 to 10 meters.

[0255] K5max: The maximum length from the strip weld to the center of the tension leveler; for this unit, it is 10m.

[0256] K5min: Minimum length from the strip weld seam to the center of the tension leveler; for this unit, it is 2m.

[0257] TLV_THCIK_N: Strip thickness of the next coil after tension leveling, in mm;

[0258] TH_MAX: The maximum strip thickness for the tension leveling machine; for this unit, it is 2.5mm.

[0259] TH_MIN: Minimum strip thickness for the tension straightening machine; for this unit, it is 0.25mm.

[0260] K6=K6max-(TLV_THCIK_N-TH_MIN)*(K6max-K6min) / (TH_MAX-TH_MIN) (9)

[0261] K6=10-(2.306-0.25)*(10-2) / (2.5-0.25)=2.69m

[0262] In formula (9), K6 is the length of the strip weld seam from the center of the tension leveling machine, in meters, preferably 2 to 10 meters.

[0263] K6max: The maximum length of the strip weld seam from the center of the tension leveler; for this unit, it is 10m.

[0264] K6min: Minimum length of the strip weld seam from the center of the tension leveler; for this unit, it is 2m.

[0265] TLV_THCIK_N: Strip thickness of the next coil after tension leveling, in mm;

[0266] TH_MAX: The maximum strip thickness for the tension leveling machine; for this unit, it is 2.5mm.

[0267] TH_MIN: Minimum strip thickness for tension straightening machine; for this unit, it is 0.25mm.

[0268] Third, the elongation switching of the strip weld over-tension straightening machine adopts different range control sections.

[0269] 1) The tension leveling machine uses elongation control for the current roll and the same for the next roll. The flattening programmable logic controller calculates the elongation control time A of the tension leveling machine according to equations (4), (5), (6) and (8), and automatically switches the elongation control of the tension leveling machine to the tension closed-loop control mode. The tension closed-loop control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0270] After the strip weld passes through the tension leveling machine, the flattening programmable logic controller calculates the elongation rate of the tension leveling machine at time point B according to equations (4), (5), (7) and (9), and automatically switches the tension closed-loop control mode of the tension leveling machine to the elongation rate control mode. The elongation rate control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0271] 2) The switching instructions for the tension straightening machine to use elongation control for the current roll and not use elongation control for the next roll are as follows: The flattening programmable logic controller calculates the elongation control time point A of the tension straightening machine according to Equations (4), (5), (6) and (8), and automatically switches the elongation control of the tension straightening machine to the tension closed-loop control mode. The tension closed-loop control mode uses the tension setting limit value calculated by Equation (1) and the tension switching slope calculated by Equation (2) for control.

[0272] 3) The tension leveling machine does not use elongation control for the current roll and uses elongation control for the next roll. After the strip weld passes through the leveling machine, the flattening programmable logic controller calculates the elongation automatic switching control time point B (73.04m) of the tension leveling machine according to equations (4), (5), (7) and (9). The tension closed-loop control mode of the tension leveling machine is automatically switched to the elongation control mode. The elongation control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

[0273] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method for controlling the elongation switching of strip welds when they pass through a tension leveling machine, characterized in that, include: Establish a tension limiting model with the cross-sectional area of ​​the strip as the independent variable; The elongation rate of the tension straightening machine adopts an automatic interval switching control mode; Construct a model with the thickness of the strip as the independent variable and the elongation switching interval. The tension limiting model is established as follows: 1) Calculate the tension setting limit of the tension straightening machine; 2) Calculate the tension switching slope of the tension straightening machine. The elongation rate of the tension straightening machine adopts an automatic interval switching control mode as follows: 1) Calculate the automatic switching control time point for the elongation rate of the tension straightening machine; 2) Calculate the elongation range based on strip thickness as the independent variable. The automatic switching control time point for the elongation rate of the tension straightening machine is calculated as follows: K4=R_8ABR1_GEAR*R_8ABR1_RD*R_PAI / R_DRIVE_PLS (4) In formula (4), K4 represents the length of the strip corresponding to each pulse, in mm / PLS; R_8ABR1_GEAR represents the gear ratio of the gearbox of the first roller on the eighth tension roller; R_8ABR1_RD represents the diameter of the first roller on the eighth tension roller, in mm; R_PAI represents pi; R_DRIVE_PLS represents the number of pulses per revolution of the motor of the first roller on the eighth tension roller. TLV_TRK_LEN= / 1000 (5) In formula (5), TLV_TRK_LEN represents the strip tracking calculation length when the strip weld passes through the weld detector, in meters; 8ABR1_RTC represents the number of pulses emitted when the first roller on the eighth tension roller rotates, in the number of pulses. TLV_TRK_LEN_A=G_WPD2_TLV_L-K5 (6) In equation (6), TLV_TRK_LEN_A represents the length at time A of the automatic elongation switching control of the tension straightener, in meters; G_WPD2_TLV_L represents the length between the weld detector and the tension straightener, in meters. K5 represents the distance between the strip weld and the center of the tension leveler when the weld has not passed through the tension leveler, in meters; TLV_TRK_LEN_B=G_WPD2_TLV_L+k6 (7) In equation (7), TLV_TRK_LEN_B represents the length of the automatic elongation switching control B of the tension straightening machine, in meters; G_WPD2_TLV_L represents the length between the weld detector and the tension straightening machine, in meters. K6 represents the distance between the strip weld after passing through the tension leveler and the center of the tension leveler, in meters (m). The elongation range based on strip thickness is calculated as follows: K5=K5max-(TLV_THCIK_N-TH_MIN)*(K5max-K5min) / (TH_MAX-TH_MIN) (8) In formula (8), K5 represents the distance between the strip weld and the center of the tension leveler before the weld passes through the tension leveler, in meters; K5max represents the maximum length of K5; K5min represents the minimum length of K5; TLV_THCIK_N represents the thickness of the next coil of strip in the tension leveler, in millimeters; TH_MAX represents the maximum thickness of the strip in the tension leveler; TH_MIN represents the minimum thickness of the strip in the tension leveler. K6=K6max-(TLV_THCIK_N-TH_MIN)*(K6max-K6min) / (TH_MAX-TH_MIN) (9) In formula (9), K6 represents the distance between the strip weld and the center of the tension leveler after passing through the tension leveler, in meters; K6max represents the maximum length of K6; K6min represents the minimum length of K6; TLV_THCIK_N represents the thickness of the next coil of strip steel after passing through the tension leveler, in mm; TH_MAX represents the maximum thickness of the strip steel after passing through the tension leveler; and TH_MIN represents the minimum thickness of the strip steel after passing through the tension leveler.

2. The method for switching and controlling the elongation of strip welds when passing through a tension leveler as described in claim 1, characterized in that, The calculation of the tension setting limit is as follows: TLV_TEN=TLV_THCIK_C*TLV_WIDTH_C*K1 / 1000 (1) In formula (1), TLV_TEN represents the limit calculation value of the set value of the tension straightening machine, in kN; TLV_THCIK_C represents the current strip thickness of the tension straightening machine, in mm; TLV_WIDTH_C represents the current strip width of the tension straightening machine, in mm. K1 represents the unit tension value of the tension leveling machine, in N / mm. 2 ; R_TLV_TEN_MAX=MIN{K2 TLV_TEN} (2) In formula (2), R_TLV_TEN_MAX represents the maximum amplitude limit of the tension straightener. The minimum value of the two is taken as the maximum amplitude limit of the tension setting of the tension straightener, and the unit is KN; K2 represents the maximum capacity value of the tension straightener; TLV_TEN represents the amplitude limit calculation value of the tension setting value of the tension straightener, and the unit is KN.

3. The method for switching and controlling the elongation of strip welds when passing through a tension leveling machine according to claim 2, characterized in that, The tension switching slope is calculated as follows: TLV_TEN_RAMP_SET=ABS(TLV_TEN_SET_C-TLV_TEN_SET_N)*R_COM_RAMP_SET_SCAN*K3(3) In equation (3), TLV_TEN_RAMP_SET represents the tension switching slope of the tension straightener, in units of KN / SCAN; TLV_TEN_SET_C represents the current roll tension setting value of the tension straightener, in units of KN; TLV_TEN_SET_N represents the next roll tension setting value of the tension straightener, in units of KN; R_COM_RAMP_SET_SCAN represents the scanning time of the leveling machine CPU, in units of seconds; and K3 represents the tension switching coefficient of the tension straightener.

4. The method for switching and controlling the elongation of strip welds when passing through a tension leveling machine according to claim 2, characterized in that, The different interval controls of the elongation switching interval model include: The tension straightener uses elongation control for the current roll and continues to use elongation control for the next roll. The tension straightener uses elongation control for the current roll but not for the next roll. The tension straightener does not use elongation control for the current roll, but uses elongation control for the next roll.

5. The elongation switching control method for strip welds passing through a tension leveler according to claim 4, characterized in that, The tension straightening machine uses elongation control for the current roll and continues to use elongation control for the next roll, as detailed below: The flattening programmable logic controller of the tension straightening machine calculates the elongation rate automatic switching control time point A of the tension straightening machine according to equations (4), (5), (6) and (8), and automatically switches the elongation rate control of the tension straightening machine to the tension closed-loop control mode; the tension closed-loop control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control. After the strip weld passes through the tension straightening machine, the flattening programmable logic controller calculates the elongation rate automatic switching control point B of the tension straightening machine according to equations (4), (5), (7) and (9), and automatically switches the tension closed-loop control mode of the tension straightening machine to the elongation rate control mode. The elongation rate control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

6. The method for switching and controlling the elongation of strip welds when passing through a tension leveling machine according to claim 4, characterized in that, The tension straightening machine uses elongation control for the current roll but not for the next roll, as detailed below: The flattening programmable logic controller of the tension straightening machine calculates the automatic switching control time point A of the elongation rate of the tension straightening machine according to equations (4), (5), (6) and (8), and automatically switches the elongation rate control of the tension straightening machine to the tension closed-loop control mode. The tension closed-loop control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

7. The method for switching and controlling the elongation of strip welds when passing through a tension leveler according to claim 4, characterized in that, The tension straightening machine does not use elongation control for the current roll, but uses elongation control for the next roll, as detailed below: After the strip weld passes through the tension straightening machine, the tension straightening machine flattening programmable logic controller calculates the elongation rate automatic switching control point B of the tension straightening machine according to equations (4), (5), (7) and (9), and automatically switches the tension closed-loop control mode of the tension straightening machine to the elongation rate control mode. The elongation rate control mode uses the tension setting limit value calculated by equation (1) and the tension switching slope calculated by equation (2) for control.

8. The method for switching and controlling the elongation of strip welds when passing through a tension leveling machine according to claim 3, characterized in that: The unit tension value K1 of the tension straightening machine is 80~160 N / mm. 2 ; The tension switching coefficient K3 of the tension straightening machine is 0.1~2; The value of pi, R_PAI, is 3.14159. When the strip weld has not passed through the tension leveling machine, the distance K5 between the weld and the center of the tension leveling machine is 2~10m; After the strip weld passes through the tension leveling machine, the distance K6 between the weld and the center of the tension leveling machine is 2~10m.

9. The method for controlling the elongation rate of strip welds when passing through a tension leveling machine according to claim 1, characterized in that: The thickness of the strip is 0.25~2.5mm, and the width is 700~1630mm; The running speed of the leveling section of the tension straightening machine is 0~220m / min.

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