Loop control method for thick plate idle passing finishing mill frame

Abstract

The invention discloses a loop control method for a thick plate to pass through a finishing mill frame, which comprises the following steps of: firstly, presetting a loop angle control program, and automatically triggering the program to compensate the torque output of a loop when the thick plate needs to pass through a certain frame during rolling; when the strip steel does not enter the front rack of the idle rack, the angle of the loop is controlled to be P; when the head of the strip steel passes through the front rack and is in contact with the loop, the loop torque required by the weight of the cross section area of the strip steel is compensated, and the loop torque is continuously adjusted according to the weight of the strip steel pressed on the loop along with advancing of the strip steel; when the strip steel enters the empty rack to bite the steel and delays for 0.5-10 seconds, the angle of the loop is adjusted to be Y; and when the current rack throws steel, the angle of the loop is adjusted to be Z until the strip steel leaves the loop. According to the method, when the thick plate passes through the rack for rolling, the loop angle is automatically fed back and controlled, a gasket does not need to be manually padded when the thick plate passes through the rack for rolling, the man-machine combination safety risk is reduced, and meanwhile the rolling efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hot continuous rolling finishing, and particularly relates to a loop control method for thick plates passing through the finishing stands empty. Background Art

[0002] Conventional hot continuous rolling finishing mainly has seven stands F1 - F7, and there are six loop devices between the seven stands. The loop plays a role in balancing the flow between stands and maintaining a constant tension between stands during hot continuous rolling. The finishing loop mainly controls the angle of the loop and the tension between stands. The loop angle control mainly ensures that there is enough loop amount between stands to guarantee the flow balance during the strip rolling process.

[0003] Since the seven stands F1 - F7 of the finishing mill rationally distribute the reduction load of each stand based on the incoming material thickness and the finished product thickness, during the rolling process of thick plates (strip finished product thickness greater than 12 mm), due to the relatively thick finished product thickness, the reduction load of the last stand of the finishing mill is relatively small, and the reduction load of the last stand has a great correlation with the properties of thick plates. Therefore, to ensure the strip properties, it is usually necessary to ensure a certain reduction rate for the last stand. Therefore, it is usually chosen to roll through the F7 stand empty during the rolling process of thick plates. To ensure the smooth biting of the strip exiting the F6 stand into the empty F7 stand, it is usually necessary for the operator to go to the site from the operation console to get gaskets to fix the angle of the 6# loop, so that the angle of the 6# loop is maintained at 11.5 - 13°. During the specific operation, there should be no strip in the rolling line area. The operator on the console selects to raise the angle of the 6# loop through the HMI screen, then the operator below the console puts the gasket into the base position of the 6# loop, and then the operator on the console lowers the 6# loop again to raise the loop angle in this way. The operation is troublesome and there are human - machine combination safety risks. At the same time, the process of putting gaskets requires no strip in the rolling line, and the reheating furnace needs to stop drawing steel, which has a great impact on the rolling rhythm. Moreover, often the height of the 6# angle does not meet the requirements after putting the gasket, and it is necessary to repeat the action of putting the gasket, with frequent human - machine combination, which has a great impact on the stable operation of the rolling line. Summary of the Invention

[0004] The purpose of the present invention is to provide a loop control method for thick plates passing through the finishing stands empty, which can realize the automatic control of the loop angle and improve the rolling efficiency.

[0005] The purpose of the present invention is achieved by the following technical solutions: A loop control method for thick plates passing through the finishing stands empty, characterized by including the following steps: (1) Preset a loop angle control program. When it is necessary to pass through a certain stand empty during the rolling of thick plates, the program is automatically triggered to output the torque for compensating the loop; (2) When the strip has not entered the stand before the stand to be passed through empty, adjust and control the initial angle of the corresponding loop to P, where P = 7 - 20°; (3) When the head of the strip passes through the front stand and contacts the loop, compensate for the loop torque required for the weight of the strip cross-sectional area; (4) As the strip advances, continuously adjust the loop torque according to the amount of strip pressed onto the loop to keep the loop at the position of angle P; (5) When the strip enters the stand that has been skipped and bites the steel, with a time delay of 0.5 - 10 seconds, control to increase the loop torque and adjust the angle of the loop to Y, where P + 3° ≤ Y ≤ P + 5°; (6) When the front stand ejects the steel, adjust the angle of the loop to Z, where Y - 4 ≤ Z ≤ Y - 2, until the strip leaves the loop.

[0006] Further, in step (2), the angle of the 6# loop in the waiting position is 11°.

[0007] Further, in step (5), when the strip enters the stand that has been skipped and bites the steel with a time delay of 0.8 seconds, adjust the angle of the loop to Y.

[0008] Further, in step (6), Z = 10°.

[0009] Further, in step (5), Y = 14°.

[0010] The beneficial effects of the present invention are as follows: By increasing the torque output for loop control, the present invention realizes automatic control of the loop angle, enables rolling of thick plates without manual padding of gaskets when skipping stands, reduces the safety risks of human-machine combined operations, and at the same time reduces the impact of manual padding of gaskets on the rolling line efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the following drawings without creative efforts.

[0012] Figure 1 It is a schematic structural diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0014] Assume the thickness of the finished strip is h (mm). When 12 ≤ h ≤ 25, during actual production, when rolling thick plates, skip the F7 stand for rolling. When h > 25, skip both the F6 stand and the F7 stand simultaneously.

[0015] The control method of the present invention will be described in detail below with the strip finishing thickness being 12 - 25 mm when passing through the F7 stand. The specific method steps are as follows.

[0016] Preset the loop angle control program. When it is necessary to pass through the F7 stand during the rolling of thick plates, the program is automatically triggered to compensate for the torque output of the No. 6 loop.

[0017] The first stage: Before the strip enters the stand, control the No. 6 loop to be in the waiting position, and the initial loop angle is 11°.

[0018] (3) The second stage: When the strip passes through the F6 stand and is about to contact the No. 6 loop, first start to compensate for the loop torque required for the weight of the strip cross-sectional area.

[0019] (4) The third stage: As the strip advances, during the process of the strip being transported from the F6 stand to the F7 stand, the total amount of strip pressing on the loop is constantly changing, and the loop torque needs to be continuously adjusted. The specific calculation method is as follows: When the head of the strip is between the F6 stand and the F7 stand, assume the length of the strip entering the loop is x, the thickness is h, the width is w, the density is p, and the acceleration due to gravity is g. The corresponding loop torque compensation F = xhwpg; thus, through the change in the length direction of the strip pressing on the upper part of the loop, the required loop torque is continuously adjusted.

[0020] (5) The fourth stage: When the strip enters the F7 stand and bites steel and delays for 0.8 seconds, control to increase the loop torque, adjust the loop angle to 14° and maintain it.

[0021] (6) The fifth stage: Continue until the strip is ejected from the F 6 stand, and the loop angle is lowered to 10° for control until the strip leaves the loop.

[0022] By controlling the output of the loop torque, the present invention achieves the control of the No. 6 loop angle during the rolling of thick plates when passing through the F7 stand empty, and realizes the function of passing through the F7 stand empty without padding gaskets for thick plates. In this way, by adopting the control method of the present invention, since there is no need for manual padding of gaskets, there can be strips on the rolling line, and the heating furnace does not need to stop drawing steel, which reduces the labor intensity of workers, ensures production safety, and at the same time improves production efficiency, and has high popularization value.

[0023] In summary, although the above preferred embodiments are listed in the present invention, it should be noted that although those skilled in the art can make various changes and modifications, unless such changes and modifications deviate from the scope of the present invention, they should all be included in the protection scope of the present invention.

Claims

1. A looper control method for thick plate passing through a finishing mill stand, characterized in that: The steps include: (1) Preset the looper angle control program. When the thick plate needs to pass through a certain frame during rolling, the program is automatically triggered to compensate for the looper torque output; (2) When the strip has not yet entered the front rack of the empty rack, the initial angle of the corresponding loop is adjusted to P, where P = 7-20°; (3) When the strip head passes through the front frame and contacts the looper, the looper torque required to compensate for the weight of the strip cross-sectional area; (4) As the strip advances, the looper torque is continuously adjusted according to the amount of strip pressed onto the looper; (5) When the strip enters the empty rack and bites the steel and delays for 0.5-10 seconds, control and increase the looper torque, and adjust the looper angle to Y, P+3°≤Y≤P+5°; (6) When the front frame throws the steel, the angle of the loop is adjusted to Z, Y-4≤Z≤Y-2, until the strip leaves the loop.

2. The method for controlling the looper of thick plate passing through the finishing mill stand according to claim 1, wherein in the step (2), the angle of the 6# looper when in the waiting position is 11°.

3. The looper control method for thick plate passing through the finishing mill stand according to claim 1 is characterized in that: In the step (5), when the strip enters the empty rack to bite the steel and delays for 0.8 seconds, the angle of the loop is adjusted to Y.

4. The looper control method for thick plate passing through the finishing mill stand according to claim 1 is characterized in that: In the step (6), Z=10°.

5. The looper control method for thick plate passing through a finishing mill stand according to any one of claims 1 to 4, characterized in that: In the step (5), Y=14°.

Images