A method for compensating static pre-pressure of the Sendzimir rolling mill

Abstract

The present invention relates to the field of rolling highly brittle materials using a Sendzimir 20-high single-stand rolling mill, and more particularly to a method for compensating for the static preload on the lead of a Sendzimir rolling mill. The method comprises two thickness gauges located on either side of the mill arch. The method corrects the static preload at the start of the first rolling pass of the Sendzimir 20-high mill for single-coil reversible rolling. The corrected static preload at the start of the first rolling pass of the Sendzimir 20-high mill is P=P0 / [1+(H1+H2) / (h1-h2)]. During the first rolling pass, operations are performed in the order of "steel coil request," "thickness gauge opening," and "pass request."

Description

Technical Field

[0001] The invention relates to the field of rolling highly brittle materials using a Sendzimir twenty-high single-stand rolling mill, and in particular to a method for compensating for static pre-pressure of a Sendzimir rolling mill strip. Background Art

[0002] The Sendzimir 20-high single-stand mill boasts high stability and a small roll diameter, primarily producing high-value-added products with high brittleness and strong deformation resistance. For single-coil reversible rolling, the system automatically calculates the static preload, commonly known as preload or fill pressure, before each pass begins. This preload is typically greater than the rolling force during normal rolling and is the sole control mechanism for ensuring the strip head thickness remains consistent with the set value. Ultra-high-grade non-oriented silicon steel and high-magnetic-induction oriented silicon steel, with silicon contents exceeding 3.1%, are highly brittle. Consequently, the exit thickness after the first fill pressure pass differs significantly from the set value, easily leading to strip breakage. This occurs because the fill pressure for the first pass is calculated by the secondary system based on the difference between the average strip thickness and the set exit thickness provided by the tertiary system, as well as other process parameters. However, the thickness of hot-rolled coils fluctuates significantly within the same coil, and the actual strip head thickness can differ significantly from the average strip thickness, sometimes exceeding 0.1mm. This ultimately results in significant deviations between the initial output thickness of the first strip head and the set value during cold rolling, leading to frequent strip breakage. The time required to process the broken strip after it is broken is long, which affects the operating efficiency of the rolling mill; the broken strip produces waste, which affects the yield rate. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: how to solve the problem of frequent strip breakage in the first rolling pass when the existing Sendzimir 20-high mill rolls highly brittle materials such as ultra-high grade non-oriented silicon steel and high magnetic induction oriented silicon steel.

[0004] The technical solution adopted by the present invention is: a method for compensating the static pre-pressure of the Sendzimir rolling mill, wherein the Sendzimir 20-high rolling mill has two thickness gauges, which are respectively located on both sides of the rolling mill arch. The static pre-pressure of the Sendzimir 20-high rolling mill with single-coil reversible rolling at the start of the first rolling is corrected. The corrected static pre-pressure of the Sendzimir 20-high rolling mill with single-coil reversible rolling at the start of the first rolling is P=P0 / [1+(H1+H2) / (h1-h2)]. During the first rolling, the operations are performed in the order of "steel coil request", "open thickness gauge", and "pass request", wherein P0 is the Sendzimir The original static pre-pressure is calculated by the secondary system at the start of the first pass of the twenty-high rolling mill and transmitted to the primary system. H1 is the difference between the strip thickness measured by the thickness gauge on the entrance side of the Sendzimir twenty-high rolling mill at the start of the first pass and the average thickness of the strip billet given by the secondary system. H2 is the difference between the strip thickness measured by the thickness gauge on the exit side of the Sendzimir twenty-high rolling mill at the start of the first pass and the set thickness for the first rolling pass. h1 is the average strip thickness provided by the secondary system at the start of the first pass of the Sendzimir twenty-high rolling mill. h2 is the set thickness for the first rolling pass of the Sendzimir twenty-high rolling mill at the start of the first pass.

[0005] The corrected static pre-pressure P at the start of the first pass of the single-coil reversible rolling Sendzimir 20-high mill is the sum of the original static pre-pressure P0 calculated by the secondary system at the start of the first pass of the Sendzimir 20-high mill and transmitted to the primary system and the pressure compensation value Pc at the start of the first pass, that is, P= P0+Pc.

[0006] The pressure compensation value Pc at the start of the first pass is the pressure value required to compensate for the difference between the actual thickness of the strip at the corresponding roll gap and the average thickness provided by the secondary system. According to the principle that the amount of reduction is proportional to the pressure under the same static conditions, the pressure compensation value Pc at the start of the first pass = P0*hc / (h1-h2), where hc is the difference between the actual thickness hp of the strip at the roll gap at the start of the first pass of the Sendzimir 20-high mill and the average thickness h1 of the strip provided by the secondary system at the start of the first pass of the Sendzimir 20-high mill, hc=hp-h1.

[0007] The actual strip thickness hp at the roll gap when the Sendzimir twenty-high mill starts for the first pass is taken as the average value of the strip thicknesses measured by the two thickness gauges when the Sendzimir twenty-high mill starts for the first pass, hp=(h1+H1+h2+H2) / 2, h1+H1 is the strip thickness measured by the thickness gauge on the entrance side when the Sendzimir twenty-high mill starts for the first pass, and h2+H2 is the strip thickness measured by the thickness gauge on the exit side when the Sendzimir twenty-high mill starts for the first pass.

[0008] The beneficial effects of the present invention are as follows: 1. The present invention does not require additional investment, and fully utilizes existing equipment and parameters to design a pressure compensation mathematical model and incorporates the mathematical model into the PLC automatic control program. 2. The implementation of the pressure compensation function described in the present invention does not require additional operating steps. 3. The present invention implements the pressure compensation function on the PLC program based on the secondary calculation of pre-pressure and the measurement of the actual thickness of the strip by the thickness gauge, which has strong adaptability and high compensation accuracy. 4. The pressure compensation mathematical model described in the present invention solves the problem of strip breakage at the start caused by thickness fluctuations of the strip head, and improves rolling efficiency and rolling yield. (1) After the implementation of the invention, the average rolling mill output increased by 10% compared with before. (2) After the implementation of the invention, the rolling yield increased by 0.7 percentage points compared with before. Implementation Method

[0009] A method for compensating static pre-pressure of the Sendzimir rolling mill

[0010] 1. The mathematical model of the compensated preload value (corrected static preload P at the start of the first pass of the single-coil reversible Sendzimir twenty-high mill) of the present invention is derived as follows:

[0011] (1) Calculation of the actual thickness of the strip at the roll gap (the actual thickness of the strip at the roll gap when the first pass of the Sendzimir 20-high mill starts)

[0012] The 20-high Sendzimir mill has two thickness gauges, one located on either side of the mill arch. Before the first pass starts, the primary system HMI screen displays the deviation between the actual thickness of the strip to be rolled and the set thickness, as measured by the thickness gauge. H1 is the difference between the strip thickness measured by the thickness gauge at the entrance of the 20-high Sendzimir mill and the average strip thickness given by the secondary system. H2 is the difference between the strip thickness measured by the thickness gauge at the exit of the 20-high Sendzimir mill and the set thickness for the first rolling pass. h1 is the average strip thickness provided by the secondary system at the first pass of the Sendzimir mill, and h2 is the set thickness for the first rolling pass of the Sendzimir mill. The actual strip thickness (hp) at the roll gap at the first pass of the Sendzimir mill is then calculated. hp is approximately equal to the average strip thickness below the entrance and exit thickness gauges, as calculated using Formula 1.

[0013] hp=(h1+H1+h2+H2) / 2 Formula 1

[0014] h1+H1 is the strip thickness measured by the thickness gauge on the entrance side at the start of the first pass of the Sendzimir twenty-high mill.

[0015] h2+H2 is the strip thickness measured by the thickness gauge on the exit side when the first pass of the Sendzimir twenty-high mill starts.

[0016] (2) The difference hc between the actual thickness hp of the strip at the roll gap when the first pass of the Sendzimir 20-high mill starts and the average thickness h1 of the strip provided by the secondary system when the first pass of the Sendzimir 20-high mill starts is calculated as shown in Formula 2.

[0017] hc=hp- h1 Formula 2.

[0018] (3) Calculation of the compensation pressure value (pressure compensation value Pc at the start of the first pass)

[0019] The compensation pressure value is the pressure required to compensate for the difference between the actual strip thickness at the corresponding roll gap and the average thickness provided by the second stage. Based on the principle that the amount of reduction is proportional to the pressure under the same static conditions, the pressure compensation value Pc at the start of the first pass is calculated as shown in Formula 3.

[0020] Pc= P0*hc / (h1-h2) Formula 3.

[0021] (4) The static preload P at the start of the first pass of the modified single-coil reversible rolling Sendzimir twenty-high mill is calculated as follows:

[0022] P= P0+Pc Formula 4.

[0023] P0 is the original static preload pressure calculated by the secondary system and transmitted to the primary system when the first pass of the Sendzimir twenty-high mill starts, which can be directly obtained in the existing system.

[0024] (5) According to Formulas 1 to 4, the mathematical model calculation results of the final output pressure compensation pressure value can be obtained, as shown in Formula 5.

[0025] P=P0 / [1+(H1+H2) / (h1-h2)] Formula 5.

[0026] 2. Edit Formula 5 in the first-level PLC control system to complete the control output of the mathematical model.

[0027] 3. Embed the automatically calculated pressure value into the operation logic.

[0028] The operating logic has been changed. The original operating sequence was "coil request," "pass request," and "thickness gauge open." The changed operating sequence is "coil request," "thickness gauge open," and "pass request." Because the "pass request" operation step includes the preload setting function, moving the "thickness gauge open" step forward allows the thickness measurement and compensation described in this invention to be integrated into the preload calculation to complete the preload compensation calculation.

[0029] In the "pass request" operation step, the compensated pre-pressure output is realized, and the PLC outputs the compensated pressure value P to the hydraulic system of the control terminal, ultimately achieving precise control of the first pass of strip pressure compensation.

Claims

1. A method for compensating static preload of a Sendzimir rolling mill, characterized in that: (1) The twenty-high Sendzimir mill has two thickness gauges, located on both sides of the mill arch. Before the first pass starts, the first-level system HMI screen shows the deviation between the actual thickness of the strip to be rolled and the set thickness measured by the thickness gauge. Among them, H1 is the difference between the strip thickness measured by the thickness gauge on the entrance side of the Sendzimir twenty-high mill at the first pass and the average thickness of the strip billet given by the secondary system. H2 is the difference between the strip thickness measured by the thickness gauge on the exit side of the Sendzimir twenty-high mill at the first pass and the set thickness for the first pass. h1 is the average thickness of the strip provided by the secondary system at the first pass of the Sendzimir twenty-high mill, and h2 is the set thickness for the first pass of the Sendzimir twenty-high mill at the first pass. Then, the actual strip thickness hp at the roll gap of the Sendzimir twenty-high mill at the first pass is calculated, where hp is equal to the average strip thickness below the entrance and exit thickness gauges, and is calculated as shown in Formula 1. hp=(h1+H1+h2+H2) / 2 Formula 1 h1+H1 is the strip thickness measured by the thickness gauge at the entrance side at the start of the first pass of the Sendzimir twenty-high mill; h2+H2 is the strip thickness measured by the thickness gauge at the exit side of the Sendzimir twenty-high mill at the start of the first pass; (2) The difference hc between the actual thickness hp of the strip at the roll gap when the Sendzimir 20-high mill starts the first pass and the average thickness h1 of the strip provided by the secondary system when the Sendzimir 20-high mill starts the first pass is calculated as shown in Formula 2; hc=hp- h1 Formula 2; (3) Calculation of the compensation pressure value, i.e., the pressure compensation value Pc at the start of the first pass The compensation pressure value is the pressure value required to compensate for the difference between the actual thickness of the strip at the corresponding roll gap and the average thickness provided by the second stage. According to the principle that the amount of reduction is proportional to the pressure under the same static conditions, the pressure compensation value Pc at the start of the first pass is calculated as shown in Formula 3. Pc= P0*hc / (h1-h2) Formula 3; (4) The static preload P at the start of the first pass of the modified single-coil reversible rolling Sendzimir twenty-high mill is calculated as follows: P= P0+Pc Formula 4; Where P0 is the original static pre-pressure calculated by the secondary system and transmitted to the primary system at the start of the first pass of the Sendzimir twenty-high mill, which can be directly obtained in the existing system; (5) According to Formulas 1 to 4, the mathematical model calculation results of the final output pressure compensation pressure value can be obtained, such as Formula 5; P={P0 / [1+(H1+H2) / (h1-h2)]} / 2 Formula 5; Edit Formula 5 in the first-level PLC control system to complete the control output of the mathematical model.