A dynamic control method for alleviating wear of the pinch rolls of a hot rolling finishing line

Abstract

The present invention discloses a dynamic control method for relieving wear of the roller surface of a hot rolling finishing line pinch roller. When the tension of the strip is greater than the friction force F provided by the pinch roller to the strip, the motor torque Tm of the pinch roller is controlled to make the traction force Fm of the pinch roller always less than the friction force F provided by the pinch roller to the strip, so that the pinch roller only moves with the running speed of the strip; and then the speed of the pinch roller is monitored in real time. When the pinch roller is accelerated or decelerated, the dynamic inertia torque of the pinch roller is obtained as the dynamic compensation of the motor torque Tm of the pinch roller, so that the traction force Fm of the pinch roller is always less than the friction force F provided by the pinch roller to the strip at a uniform speed or acceleration and deceleration, so that the pinch roller only moves with the running speed of the strip. The present invention effectively avoids the pinch roller slippage phenomenon that causes pinch roller roller surface damage and steel plate surface quality problems.

Description

Technical Field

[0001] The invention relates to a hot rolling finishing technology, and more specifically to a dynamic control method for alleviating wear on the roller surface of a pinch roller of a hot rolling finishing line. Background Art

[0002] In domestic and foreign steel enterprises, hot rolling finishing lines use a large number of tension pinch rollers to tighten the strip or balance the tension applied to the strip by other equipment. Figure 1 As shown, typically, the inlet pinch rollers of the working line at the outlet of the uncoiler need to balance the uncoiling tension, and the outlet pinch rollers (including the upper pinch roller 2 and the lower pinch roller 3) before the coiler 1 need to balance the coiling tension.

[0003] In this type of system, the uncoiler or coiler 1 is in torque control mode, the pinch roller adopts speed control mode, the pinch roller clamps the strip steel 4, and the strip steel 4 between the uncoiler, coiler 1 and the pinch roller can form strip steel tension.

[0004] The existing pinch roller control is achieved by controlling the cylinder clamping force of the pinch roller cylinder 5. The cylinder clamping force is manually adjusted according to the severity of the slip phenomenon. The main problems are as follows:

[0005] 1) When balancing the tension of the finishing line, the pinch rollers may slip, causing damage to the roller surface and quality problems of the steel plate surface:

[0006] Since the strip tension needs to be balanced by the friction force provided by the pinch rollers, when the friction force provided by the pinch rollers on the strip is less than the strip tension, slippage will occur between the strip and the roller surface of the pinch rollers. This slippage will not only cause strip surface quality problems, but also cause damage to the pinch roller surface. The damaged roller surface will aggravate the strip surface quality problems.

[0007] 2) When controlling the slippage of the pinch rollers in the finishing line, increasing the clamping force of the pinch rollers will cause severe edge waves in the strip:

[0008] Since the slippage is caused by the imbalance between the friction force provided by the pinch roller on the strip and the tension of the strip, in order to maintain the balance of the two forces, it is necessary to increase the friction force of the pinch roller on the strip, thereby increasing the clamping force of the pinch roller (friction force provided by the pinch roller on the strip = clamping force of the pinch roller x friction coefficient). However, in actual use, after increasing the clamping force of the pinch roller, the strip will have severe edge waves.

[0009] 3) When controlling the slippage of the pinch rollers in the finishing line, reducing the strip tension will cause quality defects such as strip deviation and C warping:

[0010] Similarly, in order to maintain the balance of the two forces, the strip tension needs to be reduced. However, in actual use, due to the low strip tension, quality defects such as strip deviation and C-warping will be caused, which will lead to plate quality (edge ​​wave, middle wave, C-warping, etc.);

[0011] 4) When controlling the acceleration or deceleration of the pinch roller of the finishing line, the pinch roller itself is prone to slippage due to its own inertia:

[0012] When controlling the acceleration or deceleration of the pinch rollers of the finishing line, since the acceleration or deceleration of the pinch rollers is generally completed in a short time and due to the inertia of the pinch rollers themselves, it is a common phenomenon that the strip slips when the pinch rollers are accelerated or decelerated. Summary of the invention

[0013] In view of the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide a dynamic control method for alleviating the wear of the roller surface of the pinch roller of a hot rolling finishing line, so as to effectively avoid the problems of roller surface damage and steel plate surface quality caused by inertial slip of the pinch roller during acceleration or deceleration.

[0014] To achieve the above object, the present invention adopts the following technical solution:

[0015] A dynamic control method for alleviating wear of the pinch rolls of a hot rolling finishing line:

[0016] When the pinch roller is in a uniform speed state, when the strip tension is greater than the friction force F provided by the pinch roller to the strip, the motor torque Tm of the pinch roller is controlled so that the traction force Fm of the pinch roller is always less than the friction force F provided by the pinch roller to the strip, so that the pinch roller moves only with the running speed of the strip;

[0017] The speed of the pinch roller is then monitored in real time. When the pinch roller accelerates or decelerates, the dynamic inertia torque of the pinch roller is obtained as dynamic compensation for the motor torque Tm of the pinch roller, so that the traction force Fm of the pinch roller is always smaller than the friction force F provided by the pinch roller to the strip when the speed is constant or when accelerating or decelerating, so that the pinch roller only moves with the running speed of the strip.

[0018] Preferably, the friction force F provided by the pinch roller to the strip is obtained as follows:

[0019] N=A*P

[0020] F=N*f

[0021] In the above formula, N represents the clamping force of the pinch roller, A represents the rodless cavity area of ​​the hydraulic cylinder of the pinch roller, P represents the hydraulic working pressure of the pinch roller, and f represents the friction coefficient, which ranges from 0.1 to 0.15.

[0022] Preferably, the motor torque Tm of the pinch roller is obtained as follows:

[0023] Tm=kF*r / i

[0024] In the above formula, k represents the supplement coefficient, and its value range is 0.8 to 1.2, F represents the friction force provided by the pinch roller to the strip steel, r represents the radius of the pinch roller, and i represents the speed ratio of the pinch roller.

[0025] Preferably, the dynamic compensation of the motor torque Tm of the pinch roller is obtained as follows:

[0026] Tm=kF*r / i+j*dv / dt

[0027] In the above formula, k represents the supplement coefficient, and its value range is 0.8 to 1.2, F represents the friction force provided by the pinch roller to the strip, r represents the radius of the pinch roller, i represents the speed ratio of the pinch roller, j represents the moment of inertia of the pinch roller, and dv / dt represents the acceleration of the pinch roller.

[0028] Preferably, the traction force Fm of the pinch roller is obtained as follows in a uniform speed state:

[0029] Fm=Tm*i / r

[0030] In the above formula, Tm represents the motor torque of the pinch roller, i represents the speed ratio of the pinch roller, and r represents the radius of the pinch roller.

[0031] Preferably, the torque limit of the motor torque Tm of the pinch roller is controlled by a torque limit controller.

[0032] The present invention provides a dynamic control method for reducing the wear of the roller surface of the hot rolling finishing line pinch roller, which can effectively avoid the inertial slip of the pinch roller when accelerating or decelerating, effectively avoid the pinch roller slipping causing roller surface damage and steel plate surface quality problems, while ensuring the stability of the strip surface quality, reducing the roller consumption of the pinch roller, and greatly extending the service life of the pinch roller. It also has the following beneficial effects:

[0033] 1) When balancing the tension of the finishing line, prevent the pinch roller from slipping, which will cause damage to the roller surface and quality problems of the steel plate surface. Since the tension of the strip needs to be balanced by the friction force provided by the pinch roller on the strip, when the friction force provided by the pinch roller on the strip is less than the tension of the strip, and when the tension of the strip is greater than the clamping force of the pinch roller, control the pinch roller to follow the speed of the strip to eliminate the slip between the strip and the roller surface of the pinch roller;

[0034] 2) By eliminating the slippage of the pinch rollers in the finishing line, there is no need to increase the clamping force of the pinch rollers, thus avoiding severe edge waves in the strip;

[0035] 3) By eliminating the slippage of the pinch rollers in the finishing line, there is no need to reduce the strip tension, effectively avoiding quality defects such as strip deviation and C warping;

[0036] 4) Through the inertia torque compensation control when the pinch roller accelerates or decelerates, the inertia slip problem when the pinch roller accelerates or decelerates can be effectively controlled, greatly improving the service life of the pinch roller. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the existing strip tension formed between the uncoiler, the coiler and the pinch roller;

[0038] Figure 2 It is a schematic diagram of the pinch roller and its drive and hydraulic structure;

[0039] Figure 3 It is a control principle block diagram of a dynamic control method for alleviating wear of a pinch roll on a hot rolling finishing line according to the present invention;

[0040] Figure 4 It is a schematic flow chart of a dynamic control method for alleviating wear on the roller surface of a pinch roller of a hot rolling finishing line according to the present invention. DETAILED DESCRIPTION

[0041] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0042] Combination Figure 2 As shown, the present invention provides a method for quantitatively controlling the roller surface wear of a pinch roller of a hot rolling finishing line:

[0043] When the pinch roller 6 is in a uniform speed state and the strip tension is greater than the friction force F provided by the pinch roller 6 to the strip, the motor torque Tm of the pinch roller 6 is controlled so that the traction force Fm of the pinch roller 6 is always smaller than the friction force F provided by the pinch roller 6 to the strip, so that the pinch roller 6 moves only with the running speed of the strip, thereby preventing static slippage between the pinch roller 6 and the strip.

[0044] Then monitor the speed of the pinch roller 6 in real time. When the pinch roller 6 accelerates or decelerates, the dynamic inertia torque of the pinch roller 6 is obtained as dynamic compensation for the motor torque Tm of the pinch roller 6. Dynamic control of the motor torque Tm of the pinch roller 6 is achieved, so that the traction force Fm of the pinch roller 6 is always smaller than the friction force F provided by the pinch roller 6 to the strip steel either in static or dynamic state. This ensures that the pinch roller 6 moves only with the running speed of the strip steel, and there will be no slippage between the pinch roller 6 and the strip steel due to the speed difference between the pinch roller 6 and the strip steel.

[0045] The specific control steps are as follows:

[0046] 1) First calculate the friction force F provided by the pinch roller 6 to the strip;

[0047] 2) When it is determined that the friction force F provided by the pinch roller 6 on the strip is less than the traction force Fm of the pinch roller 6, the motor torque Tm of the pinch roller 6 is limited to ensure that the traction force Fm of the pinch roller 6 is always less than the friction force F provided by the pinch roller 6 on the strip.

[0048] The friction force F provided by the pinch roller 6 to the strip is obtained as follows:

[0049] N=A*P

[0050] F=N*f

[0051] In the above formula, N represents the clamping force of the pinch roller 6, A represents the rodless cavity area of ​​the hydraulic cylinder of the pinch roller 6 (including the pinch roller transmission side cylinder 7 and the pinch roller operating side cylinder 8), P represents the hydraulic working pressure of the pinch roller 6 (collected by the PLC controller from the pinch roller transmission side cylinder 7 and the pinch roller operating side cylinder 8), and f represents the friction coefficient, which ranges from 0.1 to 0.15.

[0052] The traction force Fm of the pinch roller 6 is obtained as follows:

[0053] Fm=Tm*i / r

[0054] In the above formula, Tm represents the motor torque of the pinch roller 6 (collected and obtained by the PLC controller from the pinch roller drive motor 9), i represents the speed ratio of the pinch roller 6 (collected and obtained by the PLC controller from the pinch roller reducer 10), and r represents the radius of the pinch roller 6.

[0055] From Fm=Tm*i / r, the motor torque Tm of the pinch roller 6 can be obtained:

[0056] Tm=Fm*r / i

[0057] In the above formula, Fm is the traction force of the pinch roller 6, r is the radius of the pinch roller 6, and i is the speed ratio of the pinch roller 6 (acquired by the PLC controller from the pinch roller reduction box 10).

[0058] The above is the static control of the pinch roller 6. However, when the strip steel accelerates or decelerates, the acceleration torque of the pinch roller 6 will affect the control accuracy of the Tm torque limit. Therefore, the acceleration torque of the pinch roller 6 must be calculated for compensation:

[0059] Tm=Fm*r / i+j*dv / dt

[0060] In the above formula, Fm represents the traction force of the pinch roller 6, r represents the radius of the pinch roller 6, i represents the speed ratio of the pinch roller 6 (acquired by the PLC controller from the pinch roller reducer 10), j represents the moment of inertia of the pinch roller 6, and dv / dt represents the acceleration of the pinch roller 6.

[0061] From the above formula, we know that the traction force Fm of the pinch roller 6 needs to be smaller than the friction force F provided by the pinch roller 6 to the strip steel. Then, the friction force F provided by the pinch roller 6 to the strip steel can be substituted into the calculation formula of the traction force Fm of the pinch roller 6 to obtain the motor torque Tm of the pinch roller 6:

[0062] Tm=kF*r / i+j*dv / dt

[0063] In the above formula, F represents the friction force provided by the pinch roller 6 to the strip steel, r represents the radius of the pinch roller 6, i represents the speed ratio of the pinch roller 6 (acquired by the PLC controller from the pinch roller reducer 10), j represents the moment of inertia of the pinch roller 6, dv / dt represents the acceleration of the pinch roller, k represents the supplementary coefficient, and the value range of k is 0.8 to 1.2. Generally, the initial value of k is 1, and the coefficient k can be adapted according to the debugging situation of the specific system.

[0064] The traction force Tm of the pinch roller 6 is calculated as the torque limit of the pinch roller drive motor 9, and the torque output of the pinch roller drive motor 9 is controlled to be not greater than the Tm value. In this way, the traction force Fm of the pinch roller 6 will be smaller than the friction force F provided by the pinch roller 6 to the strip, thereby completing dynamic control. When the traction force Fm of the pinch roller 6 is smaller than the friction force F provided by the pinch roller 6 to the strip, the traction force Fm of the pinch roller 6 is dynamically and adaptively adjusted according to the load conditions. When the friction force F provided by the pinch roller 6 to the strip cannot balance the strip tension, since the traction force Fm of the pinch roller 6 is limited to be smaller than the friction force F provided by the pinch roller 6 to the strip, the pinch roller 6 will follow the strip speed and avoid slipping caused by the traction force Fm of the pinch roller 6 being larger than the friction force F provided by the pinch roller 6 to the strip.

[0065] Combination Figure 3 and Figure 4As shown, the PLC controller collects the hydraulic working pressure P of the pinch roller 6, multiplies P by the rodless cavity area A of the hydraulic cylinder of the pinch roller 6, calculates the clamping force N of the pinch roller 6, multiplies N by the friction coefficient f, and calculates the friction force F provided by the pinch roller 6 to the strip. To ensure that the traction force Fm of the pinch roller 6 is less than the friction force F provided by the pinch roller 6 to the strip, it is necessary to calculate that the traction force Fm of the pinch roller 6 is less than the friction force F provided by the pinch roller 6 to the strip. Since the pinch roller drive motor 9 controls the traction force Fm of the pinch roller 6 through the motor torque Tm of the pinch roller 6, it is necessary to calculate the allowable torque Tm corresponding to the pinch roller drive motor 9, and use this allowable torque Tm as the torque limiter Tm in the pinch roller drive controller to limit the torque output of the pinch roller drive motor 9. The pinch roller 6 The corresponding allowable torque Tm is calculated as follows: the traction force Fm of the pinch roller 6 multiplied by the radius r of the pinch roller 6 divided by the speed ratio i of the pinch roller 6. In addition, the dynamic torque of the pinch roller 6 when acceleration and deceleration occur must be calculated. The acceleration torque of the pinch roller 6 is added to the motor torque Tm of the pinch roller 6. The calculation method is to take the dv / dt output of the speed ramp generator 10 in the transmission controller and multiply it by the inertia j of the pinch roller 6. In this way, the calculated torque limit Tm of the pinch roller 6 can be dynamically adjusted according to the changes in acceleration and deceleration, and the control accuracy is higher.

[0066] The torque limit Tm is controlled by a torque limit controller 11 , and the torque limit controller 11 controls the torque output of the pinch roller drive motor 9 to be not greater than the Tm value.

[0067] Through the above control model, the traction force Fm of the pinch roller 6 will always be smaller than the friction force provided by the pinch roller 6 to the strip. When the tension of the coiler on the strip is greater than the friction force F provided by the pinch roller 6 to the strip, the pinch roller 6 will move with the speed of the steel plate to avoid damage to the roller surface of the pinch roller due to the different speeds of the pinch roller 6 and the steel plate.

[0068] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A dynamic control method for alleviating wear on the roller surface of a hot rolling finishing line pinch roller, characterized in that: When the pinch roller is in a uniform speed state, when the strip tension is greater than the friction force F provided by the pinch roller to the strip, the motor torque Tm of the pinch roller is controlled so that the traction force Fm of the pinch roller is always less than the friction force F provided by the pinch roller to the strip, so that the pinch roller moves only with the running speed of the strip; Then the speed of the pinch roller is monitored in real time. When the pinch roller is accelerated or decelerated, the dynamic inertia torque of the pinch roller is obtained as the dynamic compensation of the motor torque Tm of the pinch roller, so that the traction force Fm of the pinch roller is always smaller than the friction force F provided by the pinch roller to the strip steel at a constant speed or acceleration or deceleration, so that the pinch roller only moves with the running speed of the strip steel. The friction force F provided by the pinch roller to the strip is obtained as follows: N=A*P F=N*f In the above formula, N represents the clamping force of the pinch roller, A represents the rodless cavity area of ​​the hydraulic cylinder of the pinch roller, P represents the hydraulic working pressure of the pinch roller, and f represents the friction coefficient, which ranges from 0.1 to 0.

15. The motor torque Tm of the pinch roller is obtained as follows: Tm=kF*r / i In the above formula, k represents the supplement coefficient, the value range is 0.8~1.2, F represents the friction force provided by the pinch roller to the strip steel, r represents the radius of the pinch roller, i represents the speed ratio of the pinch roller, The dynamic compensation of the motor torque Tm of the pinch roller is obtained as follows: Tm=kF*r / i+j*dv / dt In the above formula, k represents the supplement coefficient, and its value range is 0.8 to 1.2, F represents the friction force provided by the pinch roller to the strip, r represents the radius of the pinch roller, i represents the speed ratio of the pinch roller, j represents the moment of inertia of the pinch roller, and dv / dt represents the acceleration of the pinch roller.

2. The dynamic control method for alleviating wear of the pinch rolls of a hot rolling finishing line according to claim 1, characterized in that: The traction force Fm of the pinch roller is obtained as follows in a uniform speed state: Fm=Tm*i / r In the above formula, Tm represents the motor torque of the pinch roller, i represents the speed ratio of the pinch roller, and r represents the radius of the pinch roller.

3. The dynamic control method for alleviating wear of the pinch rolls of a hot rolling finishing line according to claim 1, characterized in that: The torque limit of the motor torque Tm of the pinch roller is controlled by a torque limit controller.

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