Method for preventing strip breakage in a tandem cold rolling mill by controlling the strip edges
By determining the weld position and calculating the work roll shifting position in the cold rolling mill, the problem of strip breakage when the strip weld passes through was solved, achieving stable production and efficient product processing, and avoiding equipment damage.
Patent Information
- Application Number
- CN202410152176.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-03
- Publication Date
- 2026-02-27
- Estimated Expiration
- 2044-02-03
AI Technical Summary
When the strip passes through the weld seam of the cold rolling mill, the strip breaks due to interference from the control of the work roll shifting, which affects production stability and yield.
By determining the weld position and calculating the position of the work roll, control interference is avoided when the weld passes through the conical area. A PLC control system is used to achieve precise adjustment of the work roll position, ensuring the safe passage of the weld.
Reduce the risk of strip breakage, improve production efficiency and yield, reduce equipment damage, and ensure the stable operation of the cold rolling mill and product quality.
Smart Images
Figure CN118002620B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of automated control technology for cold rolling mills, and relates to the control of strip edge drop during cold rolling and the prevention of strip weld breakage. Specifically, it is a method for controlling the strip edge drop in a cold rolling mill to prevent strip breakage. Background Technology
[0002] Cold-rolled silicon steel products are essential soft magnetic alloys for the power, electronics, and military industries. The precision of transverse thickness control in cold rolling directly affects the stamping quality of end products and the yield of production lines. Edge drop is the main source of transverse thickness differences in strip during cold rolling. During rolling, the elastic flattening of the work rolls and the transverse flow of metal in the strip edge area cause thinning at the strip edges. This phenomenon, where the strip thickness decreases sharply at a certain distance from both sides, is called edge drop. Cold continuous rolling mills control the movement of the work rolls in the front stands to automatically reduce the area of edge drop in the strip width direction, thereby improving the yield. However, this control can also easily lead to strip breakage accidents due to excessive work roll movement during the strip weld's passage through the front mill.
[0003] Taking a five-stand continuous rolling mill as an example, the raw strip steel is continuously rolled through five stands. Each stand's roll system contains six rolls, with the upper and lower work rolls in direct contact with the strip steel. The edge reduction control method for cold continuous rolling mills is as follows: tapered work rolls are used in stands #1 and #2 for roll shifting. By utilizing the effective tapered section length of the strip edge, the edge of the strip steel thickens during rolling, thereby controlling edge thinning. When the tapered section insertion amount is combined with the axial displacement (roll shifting) rolling method, edge control of strip steel of various steel grades, widths, and thicknesses can be achieved. However, there are also obvious problems. When the weld passes through the conical area on the edge of the work roll of the continuous rolling mill, the difference between the deformation at the edge and the deformation at the center of the strip can easily cause the strip to tear and break from the edge. In order to prevent the weld from stopping or breaking due to the conical work roll, the conical work rolls of stands 1 and 2 must move to avoid the conical position before the weld arrives, so that the flat roll area contacts the strip and ensures that the weld passes through the mill safely. At the same time, the edge drop status of the strip reflected by the edge drop instrument will be fed back, and the position of the work roll will be controlled by the edge drop control program. When the two control methods are used at the same time, the edge drop control will interfere with the control of the roll movement when the weld arrives. This will not only cause the upper and lower work rolls to exceed the limit and stop, but in severe cases, the difference in the amount of roll movement between the upper and lower work rolls of stands 1 and 2 may even cause the strip to break, affecting normal production and causing equipment damage. Summary of the Invention
[0004] The purpose of this invention is to provide a method for controlling the edge drop of strip in a cold continuous rolling mill to prevent strip breakage. This method can ensure the original edge drop control of strip in a cold continuous rolling mill while improving the control process of work roll shifting, ensuring stable production and obtaining good edge drop data for strip products. It avoids shutdowns and strip breakage caused by work roll shifting, effectively improving production efficiency and yield, and ensuring controlled product quality.
[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:
[0006] A method for controlling the edge drop of strip steel in a cold continuous rolling mill to prevent strip breakage includes the following steps:
[0007] S1. Determine whether the continuous rolling mill can operate continuously and execute the corresponding control commands;
[0008] S11. If the continuous rolling mill is not running continuously and needs to be stopped, select the manual control command on the control panel.
[0009] S12. If a roll change is required, select the work roll shifting control command;
[0010] S2. If the continuous rolling mill can run continuously, determine whether the weld is about to enter the edge drop control stand of the continuous rolling mill and execute the corresponding roll shifting position control command; by reading the preset strip width information, calculate the work roll shifting position when the weld safely passes through;
[0011] S21. If there is no weld seam about to enter the continuous rolling mill stand, calculate the work roll shifting position command based on the edge drop instrument measurement signal, and execute the edge drop control to adjust the shifting roll position control command.
[0012] S22. If a weld is about to enter the continuous rolling mill stand, execute the edge drop control roll position control command before the weld arrives on the upper and lower work rolls of the stand; at the same time, interrupt the edge drop control adjustment roll position control command described in S21.
[0013] S3. Determine whether the weld has passed through the edge drop control stand of the continuous rolling mill, and execute the corresponding roll position control command;
[0014] S31. When the weld seam has not passed through the continuous rolling mill stand, continue to execute the roll position control command for the upper and lower work rolls of the stand before the weld seam arrives; at the same time, interrupt the edge drop control adjustment roll position control command.
[0015] S32. When the weld has passed through the continuous rolling mill stand, execute the edge drop control adjustment roll position control command.
[0016] The beneficial effects of this invention are:
[0017] 1. Reduce the risk of strip breakage caused by edge drop control of work rolls during strip production, improve work efficiency and equipment uptime, ensure continuous and stable operation of cold rolling mills, avoid downtime, scrap volume and damage to equipment caused by strip breakage due to fault shutdowns, and reduce energy consumption during abnormal shutdowns of the unit.
[0018] 2. This method has a low PLC load and high operational stability. It can help users avoid strip breakage caused by edge control, ensure the quality of unit products, and increase production, reduce costs and improve efficiency. Attached Figure Description
[0019] Figure 1 This is a flowchart illustrating the design process of the method of this invention;
[0020] Figure 2 This is a schematic diagram of edge drop control in the cold continuous rolling mill of the present invention;
[0021] In the diagram, a is rack #1; b is rack #2; c is rack #3; d is rack #4; and e is rack #5. Detailed Implementation
[0022] The present invention will be further described below with reference to embodiments and accompanying drawings:
[0023] A method for controlling the edge drop of strip steel in a cold continuous rolling mill to prevent strip breakage, the specific process is as follows: Figure 1 The above,
[0024] First, determine whether the continuous rolling mill can operate continuously; if the continuous rolling mill cannot operate continuously and needs to be stopped, select the manual control command on the control panel; if a roll change is required, select the work roll shifting control command during roll change.
[0025] When it is determined that the continuous rolling mill can operate continuously, it is determined whether the weld is about to enter the continuous rolling mill stand;
[0026] Determine whether the weld is about to enter the edge drop control stand of the continuous rolling mill. If there is no situation where the weld is about to enter the continuous rolling mill stand, calculate the work roll shifting position command based on the edge drop instrument measurement signal, and the edge drop control stand executes the edge drop control adjustment roll position control command.
[0027] If a weld is about to enter the edge drop control stand of the continuous rolling mill, execute the roll shifting position control command for the upper and lower work rolls of the edge drop control stand before the weld arrives; at the same time, interrupt the aforementioned edge drop control adjustment roll shifting position control command.
[0028] By reading the preset strip width information, the position of the work roll shifting when the weld seam safely passes is calculated, that is, the position of the upper and lower work rolls of the edge drop control frame before the weld seam arrives. The specific calculation method is as follows:
[0029] Let the length of the work roll be L, the stroke of the hydraulic cylinder for the roll shifting be C, the strip width be W, the length of the work roll taper safely passing through the weld compensation section be Δ, the zero position of the roll shifting is S0 when the center of the work roll coincides with the center of the strip, and the safe position of the roll shifting when the weld safely passes through the work roll of the rolling mill is S. wp ,but:
[0030]
[0031] s wp =s0+Δ......Formula 2
[0032] The safe position of the weld seam passing through the working rolls of the rolling mill is S. wp :
[0033]
[0034] The calculation process and control instructions of Formula 1, Formula 2, and Formula 3 are edited into the PLC control system to complete the control output of the mathematical model.
[0035] Finally, determine whether the weld has passed through the edge drop control stand of the continuous rolling mill;
[0036] If the weld seam does not pass through the continuous rolling edge drop control stand, the roll position control command for the upper and lower work rolls of the edge drop control stand before the weld seam arrives will continue to be executed; at the same time, the edge drop control adjustment roll position control command will be interrupted.
[0037] Once the weld has passed through the continuous rolling edge drop control stand, the edge drop control adjustment roll position control command is executed.
[0038] Taking a 5-stand continuous rolling mill using a Hitachi PLC control system as an example, such as Figure 2 The diagram shows the edge drop control of a cold rolling mill; the edge drop control stand control program includes:
[0039] The variable table is shown below.
[0040]
[0041]
[0042] 1. Based on the strip width, calculate the safe position S of the weld seam for passing safely through the work rolls of stands #1 and #2. WP ;
[0043] 2. Position the work roll to the safe position S. WP The position is converted into the execution data of the working roll shifting cylinder;
[0044] 3. When the weld inspection instrument located in front of the cold rolling mill stand detects the arrival of a weld, it issues a warning to the upper and lower work rolls of stands #1 and #2 to move to the safe position S.WP The command to start the roll shifting is executed, and at the same time the control command to cut off the upper and lower work rolls of frames 1 and 2 according to the edge drop adjustment is executed.
[0045] 4. Assign the calculation results from step 2 to the control output command of the roller cylinder, and execute the roller movement to the corresponding position, waiting for the strip weld to pass through frame 1 and frame 2;
[0046] 5. After the weld passes through frames 1 and 2, restart the edge drop control to adjust the position of the working rollers on frames 1 and 2, and the unit will resume edge drop control.
[0047] After this control program was put into use, it reduced the number of unit shutdowns and strip breaks caused by excessive movement of the edge drop control work rolls during silicon steel rolling in cold continuous rolling mills. The downtime caused by malfunctions was reduced by 4 hours per month, which translates to an additional 48 hours of work per year. Based on the normal production capacity efficiency of 120 tons per hour for pickling and rolling, the output increased by more than 5,000 tons, resulting in a significant increase in efficiency.
Claims
1. A method of preventing strip breakage in a cold tandem mill strip edge lowering control, characterized by: The method comprises the following steps: S1, judging whether the continuous rolling mill can continuously run or not, and executing corresponding control instructions; S11, if the continuous rolling mill needs to stop running, selecting the operation table manual control instructions; S12, if the work roll needs to be changed, selecting the work roll shifting control instructions; S2, if the continuous rolling mill can continuously run, judging whether the weld will enter the edge drop control mill or not, and executing corresponding shifting position control instructions; calculating the work roll shifting position when the weld safely passes through by reading the preset strip width information; S21, if it is judged that there is no weld which will enter the edge drop control mill, calculating the work roll shifting position instructions according to the edge drop instrument measuring signal, and executing the edge drop control adjusting shifting position control instructions; S22, if it is judged that there is a weld which will enter the edge drop control mill, executing the shifting position control instructions of the upper and lower work rolls of the edge drop control mill before the weld arrives; at the same time, interrupting the edge drop control adjusting shifting position control instructions in S21; S3, judging whether the weld has passed through the edge drop control mill or not, and executing corresponding shifting position control instructions; S31, when it is judged that the weld has not passed through the edge drop control mill, continuing to execute the shifting position control instructions of the upper and lower work rolls of the edge drop control mill before the weld arrives; at the same time, interrupting the edge drop control adjusting shifting position control instructions; S32, when it is judged that the weld has passed through the edge drop control mill, executing the edge drop control adjusting shifting position control instructions; In S2, the calculation method of the work roll shifting position when the weld safely passes through by reading the preset strip width information is: Let the length of the work roll be L, the stroke of the roll shifting hydraulic cylinder be C, the width of the strip be W, the length of the work roll taper safety through the weld compensation part be Δ, the roll shifting zero position when the center of the work roll coincides with the center of the strip be S0, and the roll shifting safety position when the weld safely passes through the work roll of the rolling mill be S wp Then: ； ； The roll gap safety position S for the weld seam to safely pass through the work rolls of the rolling mill wp : 。