A method for loop optimization control in high speed bar rolling

Abstract

The application provides a method for loop optimization control in high-speed bar rolling, a loop control model with faster dynamic response speed is developed, and the proportional coefficient of a PID regulator is dynamically adjusted according to the deviation value between the actual value of the loop height and the set value of the loop height: when the deviation value is less than 30 mm and greater than or equal to 10 mm, the proportional coefficient is increased to 8; when the deviation value is less than 10 mm and greater than or equal to 5 mm, the proportional coefficient Kp is reduced to 5, and the proportional coefficient is appropriately reduced to 5; when the deviation value is less than 5 mm and greater than or equal to 1 mm, the proportional coefficient is reduced to 2; through the dynamic adjustment of the proportional coefficient of the PID regulator, the quick response of the rolling mill speed adjustment amount can be realized, the actual value of the loop height is adjusted to the set value of the loop height in the shortest time, the problem of slow loop adjustment is solved, the adjustment time is reduced to 100 ms through detection, the adjustment time is reduced by 50%, and the effect of stable loop control is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rolling loop control, in particular to a method for optimizing loop control in high-speed bar rolling. BACKGROUND

[0002] A certain high-speed bar production line is the first full-automatic production line in China to introduce foreign Westmark imported equipment, with a design annual output of 1 million tons, and the main products are 10-50 threaded steel. The pre-finishing and finishing 6-arch unit adopts a flat-stand-flat-flat-flat-flat arrangement. Since it was put into operation, the pre-finishing and finishing area has often experienced slow loop lifting, slow rolling mill speed adjustment, and unstable loop lifting and falling.

[0003] The variable speed difference control is a loop amount control (△v-△H), and the basic process is head loop lifting-middle loop stabilizing to set loop amount-tail loop closing. The actual value of the loop height is measured and fed back by the loop scanner, and is compared with the set value of the loop height. Then, the deviation value is used as the correction signal of the loop regulator, and the PID regulation output is used to adjust the speed of the upstream stand. This regulation method has a slow speed adjustment, which is difficult to meet the actual needs of the site production.

[0004] Therefore, it is necessary to redesign the loop control program model and develop a pre-finishing and finishing loop proportional coefficient dynamic response algorithm to ensure the stability of the high-speed bar product size precision, realize tensionless rolling, and eliminate the tension fluctuation caused by various dynamic disturbances in the rolling process. SUMMARY

[0005] The purpose of the present application is to provide a method for optimizing loop control in high-speed bar rolling.

[0006] To solve the above technical problems, the technical solution provided by the present application is:

[0007] A method for optimizing loop control in high-speed bar rolling, the loop is controlled by a PID controller with a differential, the rotational speed of the roll of the upstream rolling mill adjacent to the loop is calculated by a PID calculation model, and the PID calculation model includes a proportional coefficient Kp;

[0008] When the deviation value between the actual value of the loop height and the set value of the loop height is less than 30mm and greater than or equal to 10mm, the proportional coefficient Kp is increased to 8;

[0009] When the deviation value between the actual value of the loop height and the set value of the loop height is less than 10mm and greater than or equal to 5mm, the proportional coefficient Kp is reduced to 5;

[0010] When the deviation value between the actual value of the loop height and the set value of the loop height is less than 5mm and greater than or equal to 1mm, the proportional coefficient Kp is reduced to 2.

[0011] Preferably, there are 8 looper in the rolling production line, specifically: 2 loops are arranged in the medium rolling, 4 loops are arranged in the pre-finishing rolling, and 2 loops are arranged in the finishing rolling.

[0012] The application provides a looper optimization control method in high-speed bar rolling, a looper control model with faster dynamic response speed is redeveloped in view of the defects of the existing looper automatic control program, and the proportional coefficient of a PID regulator is dynamically adjusted according to the deviation value between the actual looper height value and the looper height set value:

[0013] When the deviation value is less than 30 mm and greater than or equal to 10 mm, the proportional coefficient is increased to 8;

[0014] When the deviation value is less than 10 mm and greater than or equal to 5 mm, the proportional coefficient Kp is reduced to 5, and the proportional coefficient is appropriately reduced to 5;

[0015] When the deviation value is less than 5 mm and greater than or equal to 1 mm, the proportional coefficient is reduced to 2;

[0016] By dynamically adjusting the proportional coefficient of the PID regulator, the quick response of the rolling mill speed adjustment amount can be realized, and the actual looper height value is adjusted to the looper height set value in the shortest time, so that the problem of slow looper adjustment can be solved, and the adjustment time of the actual looper height value to the looper height set value is reduced to 100 ms, the adjustment time is reduced by 50%, and the effect of stable looper control is achieved. DETAILED DESCRIPTION

[0017] To make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below in combination with the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0018] The application provides a looper optimization control method in high-speed bar rolling, a looper is controlled by a PID controller with differentiation, and the rotational speed of a roll of a rolling mill close to the looper is calculated by a PID calculation model, the PID calculation model including a proportional coefficient Kp.

[0019] When the deviation value between the actual looper height value and the looper height set value is less than 30 mm and greater than or equal to 10 mm, the proportional coefficient Kp is increased to 8;

[0020] When the deviation value between the actual looper height value and the looper height set value is less than 10 mm and greater than or equal to 5 mm, the proportional coefficient Kp is reduced to 5;

[0021] When the deviation between the actual value of loop height and the set value of loop height is less than 5 mm and greater than or equal to 1 mm, the proportional coefficient Kp is decreased to 2.

[0022] In an embodiment of the present application, there are totally 8 loops in the rolling production line, specifically, 2 loops are arranged in the intermediate rolling, 4 loops are arranged in the pre-finishing rolling, and 2 loops are arranged in the finishing rolling.

[0023] In the present application, the loop is a means for detecting and adjusting the speed relationship between adjacent stands to achieve tension-free rolling. Loop control is based on the measurement of the difference in metal second flow between adjacent stands, which leads to steel stacking or pulling between stands. The workpiece is guided by the loop-up roller to form a loop. The online loop scanner can provide real-time feedback of the actual loop height. The control system compares the actual loop height with the set loop height to generate a speed correction signal, which adjusts the speed of the upstream stand to maintain the loop height (loop amount) at a given value, thereby achieving correct speed matching between the front and rear stands. When the upstream pass metal second flow is less than the downstream pass metal second flow, the loop amount gradually decreases, and the loop height decreases. When the metal second flow is equal, the loop height remains unchanged. Loop control is achieved by changing the speed of the stand related to the loop. The loop is composed of a loop table, support rollers, guide grooves, loop-up rollers, and loop scanners. The support rollers and loop-up rollers play a guiding and supporting role for the workpiece. The loop-up rollers and turning guide plates are driven by air cylinders, and the loop-up roller air cylinder is controlled by double electromagnetic valves.

[0024] In the present application, the loop control function is suitable for situations where the rolling speed is fast and the cross-section of the workpiece is small. It can eliminate the interference of dynamic speed changes of the continuous rolling stand, ensure the precision of the workpiece, and achieve tension-free rolling. Tension-free rolling means that there is no tension between the workpieces in the rolling process. It is achieved by changing the loop storage amount. When the workpiece between the adjacent two stands is pulled, the loop amount decreases, which can act as a buffer to prevent tension between the stands and prevent the workpiece cross-section from being pulled and shrunk, affecting the precision of the workpiece size. On the other hand, it absorbs excess workpieces to prevent steel stacking accidents between stands. However, the loop amount adjustment range and the loop storage amount are limited. When the loop amount deviates too much due to unreasonable speed matching between adjacent stands or other reasons, the automatic control system cannot adjust in time or cannot adjust, which may cause steel stacking. When the loop size changes due to external conditions and the actual loop amount is not equal to the set loop amount, the loop regulator has an output, which changes the speed of the upstream stand of the loop through the speed adjustment system, and adjusts the speed of all upstream stands in a reverse cascade manner. This adjustment may vary for each steel until it stabilizes.

[0025] In the application, after the sleeve is completed, it enters the stable control phase of the looper. According to the continuously changing sleeve amount obtained by the looper scanner, the electric control pulse signal is continuously transmitted to the electric control system, and the system adjusts the speed of the adjacent upstream 14 stands in the direction of reverse cascade control, which is equivalent to continuously correcting the speed of the adjacent 14 stands upstream to ensure that the height of the looper is consistent with the looper height set value. The looper adjustment is to compensate for the sleeve amount change caused by the size or temperature change of the rolled piece. The operator should also closely monitor the operation of the looper. When the looper height exceeds the maximum allowed height or there is a serious steel drawing situation, the automatic control is invalid due to exceeding the automatic control adjustment range of the looper, and manual control should be taken in time to ensure the safe production.

[0026] In the application, the looper sleeve control process is taken as an example of the looper between the 14th and 15th stands, and the other loopers are similar. When the looper scanner of the 14th stand detects the head of the rolled piece and delays for t1 seconds, the automatic control system sends a sleeve starting signal to the electromagnetic valve. The determination of the sleeve starting delay t1 seconds (the time obtained by dividing the distance between the 14th and 15th stands by the outlet speed of the 14th stand to consider the delay of the cylinder action) should ensure that the rolled piece just bites into the 15th stand when the sleeve roll just starts. After the sleeve roll starts, the 14 stands upstream of the looper increase the speed to generate "excess" rolled piece between the 14th and 15th stands to generate the looper. After the sleeve process is completed, the 14th stand restores the looper height set value. According to the dynamic characteristics of the motor, when the rolled piece just bites into the 15th stand, the motor will produce a dynamic speed drop, but the control system will give the 15th stand a dynamic speed drop compensation of 2% to 4% in advance, which can ensure that there will be too much "excess" rolled piece when biting in at the beginning, i.e. the initial sleeve height is 0. This can be confirmed by the fact that the looper is not put into operation but can still bite smoothly.

[0027] In the application, the PID controller is used to control the control amount by using proportion, integration and differentiation according to the error of the system, including proportion (P) control, integration (I) control and differentiation (D) control.

[0028] In the application, reverse regulation is adopted, that is, when the height of a looper changes, all the stands in front of the looper should adjust the speed according to the cascade speed regulation proportion of the looper sleeve height adjustment amount. In order to achieve fast response, PID control with differentiation is adopted.

[0029] The methods and devices not described in detail in the application are all prior art and will not be described again.

[0030] The above examples are only used to help understand the method of the application and its core idea. It should be pointed out that for ordinary skilled persons in the technical field, some improvements and modifications can be made to the application without departing from the principles of the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

Claims

1. A method for loop optimization control in high speed bar rolling, characterized by, The loop is controlled by a PID controller with a differential, the rotational speed of the roll of the rolling mill immediately upstream of the loop is calculated by a PID calculation model, the PID calculation model including a proportional coefficient Kp; When the deviation between the actual value of the loop height and the set value of the loop height is less than 30mm and greater than or equal to 10mm, the proportional coefficient Kp is increased to 8; When the deviation between the actual value of the loop height and the set value of the loop height is less than 10mm and greater than or equal to 5mm, the proportional coefficient Kp is reduced to 5; When the deviation between the actual value of the loop height and the set value of the loop height is less than 5mm and greater than or equal to 1mm, the proportional coefficient Kp is reduced to 2.

2. A method for loop optimization control in high speed bar rolling as claimed in claim 1 wherein, There are 8 loops in the rolling production line, specifically, 2 loops are arranged in the intermediate rolling, 4 loops are arranged in the pre-precision rolling, and 2 loops are arranged in the precision rolling.