A method for thickness control in a single-stand reversible cold rolling mill

Abstract

This invention provides a thickness control method for a single-stand reversible cold rolling mill. The single-stand reversible cold rolling mill unit includes an inlet coiler, an outlet coiler, a mill body, a mill hydraulic system, an inlet thickness gauge, an outlet thickness gauge, an inlet speed gauge, an outlet speed gauge, an inlet tension gauge, and an outlet tension gauge. The single-stand reversible cold rolling mill unit also includes an S-roll, with S-rolls at both the inlet and outlet of the unit. The S-roll can rotate 180°, with the upper roll of the S-roll able to rotate to the lower roll position and the lower roll of the S-roll able to rotate to the upper roll position. The 180° rotation causes the strip steel to wind in an S-shape on the S-roll. The thickness difference of the strip steel is eliminated by adjusting the speed of the inlet S-roll to control the metal flow rate entering the roll gap.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for rolling mills, and in particular to a thickness control method for a single-stand reversible cold rolling mill. Background Technology

[0002] Single-stand reversible cold rolling mill Figure 1 The rolling mill equipment typically includes an inlet coiler, an outlet coiler, the mill body, a hydraulic pressing (or pressing) system, inlet guide rolls, and outlet guide rolls. Some may also include an uncoiler. Figure 1 The diagram illustrates a 6-roll mill, but other types (such as 4-roll, 18-roll, and 20-roll mills) can also be used. The coiler and mill body are driven by large electric motors, providing inlet and outlet tension and rolling torque. Inlet and outlet guide rolls may also have follow-drive motors, but in most cases, they are not. The hydraulic reduction system provides the rolling force to reduce the strip thickness. Large measuring instruments mainly include inlet and outlet thickness gauges, inlet and outlet tension gauges (or integrated into the strip rolls), and inlet and outlet speed gauges, used to measure strip thickness, tension, and speed at the inlet and outlet. Inlet and outlet speed measurement can be achieved using independent laser speed measurement or encoders on the guide rolls; laser speed measurement is used here. For control, the coiler typically uses direct or indirect tension control. If equipped with inlet and outlet tension gauges, direct tension control is used; otherwise, indirect tension control is used based on the tension setpoint. The main motor of the mill body uses speed control to ensure the mill operates at the set speed.

[0003] In terms of automatic thickness control (AGC), conventional AGC methods currently include feedforward AGC, flow rate AGC, monitoring AGC, and acceleration / deceleration compensation. The feedforward AGC relies on the inlet thickness deviation Δh0 = (h0 - h0*) measured by the inlet thickness gauge, where h0 is the actual inlet thickness measured by the inlet thickness gauge and h0* is the set inlet thickness. Based on the thickness control bounce formula, the corresponding roll gap adjustment Δs1 = Δh0 × M / K is calculated, where M is the strip plastic stiffness and K is the frame elastic stiffness. This adjustment is directly applied to the pressing system to complete the corresponding roll gap adjustment, eliminating the influence of the inlet thickness difference on the outlet strip thickness. The monitoring AGC relies on the outlet thickness deviation Δh1 = (h1 - h1*) measured by the outlet thickness gauge, where h1 is the actual outlet strip thickness measured by the outlet thickness gauge and h1* is the set outlet thickness. Based on the thickness control bounce formula, the corresponding roll gap adjustment Δs2 = Δh1 × (M + K) / K is calculated and directly applied to the pressing system to eliminate the outlet thickness difference. However, the outlet thickness gauge is located at the outlet of the frame, causing a lag in the monitoring AGC, which is often used for long-cycle outlet thickness difference adjustment. The flow rate AGC relies on the actual inlet speed v0 of the strip measured by the inlet velocity meter, the actual outlet speed v1 of the strip measured by the outlet velocity meter, and the actual inlet thickness h0. Based on the principle of constant volume (cold rolling does not widen), it calculates the current roll gap outlet thickness h1. j=h0×v0 / v1, thus the calculated exit thickness deviation △h1 can be obtained. j =(h1) j (-h1*), similar to the AGC monitoring method, can calculate the corresponding roll gap adjustment △s3 to eliminate the exit thickness difference. Acceleration and deceleration compensation eliminates the impact of rolling force changes caused by changes in rolling speed, resulting in changes in roll gap and strip exit thickness. The model predicts the changes in acceleration and deceleration rolling force and calculates the corresponding roll gap change △s4. Reverse compensation ensures the stability of the roll gap.

[0004] All of the above-mentioned AGC control methods eliminate thickness difference by adjusting the roll gap, i.e., pressing-type thickness difference adjustment. When rolling hard strip steel or thin strip steel, the stiffness ratio M / K between the strip steel and the stand is often relatively large. If the ratio is greater than 5, the roll gap adjustment amount corresponding to the thickness difference is relatively large. During high-speed rolling, the hydraulic pressing system is difficult to adjust in a timely and accurate manner, which easily leads to under-adjustment and over-adjustment, making it difficult to further reduce the thickness difference.

[0005] Therefore, it is necessary to design a new thickness control method for a single-stand reversible cold rolling mill to overcome the above problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art and provide a method for thickness control of a single-stand reversible cold rolling mill. This invention solves at least some of the problems in the prior art.

[0007] This invention is implemented as follows:

[0008] This invention provides a thickness control method for a single-stand reversible cold rolling mill. The single-stand reversible cold rolling mill unit includes an inlet coiler, an outlet coiler, a mill body, a mill hydraulic system, an inlet thickness gauge, an outlet thickness gauge, an inlet speed gauge, an outlet speed gauge, an inlet tension gauge, and an outlet tension gauge. The single-stand reversible cold rolling mill unit also includes an S-roll, with S-rolls at both the inlet and outlet of the unit. The S-roll can rotate 180°, with the upper roll of the S-roll able to rotate to the lower roll position and the lower roll of the S-roll able to rotate to the upper roll position. The 180° rotation causes the strip steel to wind in an S-shape on the S-roll. The thickness difference of the strip steel is eliminated by adjusting the speed of the inlet S-roll to control the metal flow rate entering the roll gap.

[0009] Furthermore, the S-roller is equipped with a motor drive.

[0010] Furthermore, a speed AGC module and a tension roll gap control model are added to the unit's PLC control program, with the S-roller serving as the adjustment actuator for the speed AGC module.

[0011] Furthermore, during forward rolling, the inlet S-roll rotates 180° to form a winding with the strip before being put into operation, while the outlet S-roll is not put into operation. The lower roll of the outlet S-roll is used as a guide roll, and the inlet coiler is used for indirect tension control. During reverse rolling, the outlet S-roll rotates 180° to form a winding with the strip before being put into operation, while the inlet S-roll is not put into operation. The lower roll of the inlet S-roll is used as a guide roll, and the outlet coiler is used for indirect tension control.

[0012] Furthermore, during forward rolling, the inlet S-roll speed adjustment is Δv0 = Δv01 + Δv02 + Δv03. The speed adjustment corresponding to the feedforward inlet thickness difference is Δv01 = -Δh0 × v0 / h0, where Δh0 is the inlet thickness deviation measured by the feedforward AGC using the inlet thickness gauge, v0 is the actual inlet speed of the strip measured by the inlet speed gauge, and h0 is the actual inlet thickness measured by the inlet thickness gauge. The speed adjustment corresponding to monitoring is Δv02 = -Δh1 × v0 / h1, where Δh1 is the outlet thickness deviation measured by the monitoring AGC using the outlet thickness gauge, h1 is the actual outlet strip thickness measured by the outlet thickness gauge, and v0 is the actual inlet speed of the strip measured by the inlet speed gauge. The speed adjustment corresponding to the flow rate per second is Δv03 = -Δh1. j ×v0 / h1,△h1 j h1 represents the actual thickness deviation at the exit, and v0 represents the actual thickness of the strip at the exit measured by the thickness gauge.

[0013] Furthermore, in order to avoid fluctuations in the inlet tension of the frame caused by the adjustment of the S-roll speed, it is necessary to adjust the roll gap accordingly based on the measured tension difference at the inlet ΔT0=(T0-T0*), where T0 is the measured tension at the inlet and T0* is the set tension at the inlet, Δs5=K1×ΔT0, where K1 is the efficiency coefficient of tension and roll gap.

[0014] This invention provides a thickness control method for a single-stand reversible cold rolling mill, which can better eliminate strip thickness difference and avoid the impact of thickness difference on the thickness of the exit strip. It is superior to traditional methods in terms of thickness control. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a standard AGC (Automatic Guided Vehicle).

[0017] Figure 2 A schematic diagram of advanced AGC provided for embodiments of the present invention;

[0018] Figure 3 This is a schematic diagram of advanced AGC forward rolling provided in an embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram of advanced AGC negative rolling provided in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] like Figures 1-4 This invention provides a thickness control method for a single-stand reversible cold rolling mill, introducing an inlet S-roll speed AGC (Automatic Guided Control) to further eliminate strip thickness differences by adjusting the inlet S-roll speed to control the metal flow rate entering the roll gap. First, the mill needs to be equipped with inlet and outlet S-rolls to replace the inlet and outlet guide rolls, serving as the speed AGC adjustment actuator. This S-roll should be equipped with a motor drive; whether it is a single-roll drive or a double-roll drive is determined as needed. Furthermore, this S-roll can rotate 180°, meaning the upper roll can rotate to the lower roll position, and the lower roll can rotate to the upper roll position, ensuring that when the S-roll is needed, a 180° rotation allows the strip to wind in an S-shape on the S-roll. In addition, a speed AGC module and a tension roll gap control model are added to the PLC control program. Figure 2 This ensures the control of the unit's thickness.

[0022] During forward rolling ( Figure 3 After the inlet S-roll rotates 180° to form a winding with the strip, it is put into production. The outlet S-roll is not put into operation; its lower roll is used as a guide roll. The inlet coiler is changed from direct tension control to indirect tension control. At this time, an advanced AGC mode is adopted, which adds speed AGC and inlet tension roll gap control to the conventional AGC. That is, the inlet S-roll speed adjustment △v0=△v01+△v02+△v03; where the speed adjustment amount corresponding to the inlet thickness difference (feedforward) △v01=-△h0×v0 / h0; the speed adjustment amount corresponding to the monitoring △v02=-△h1×v0 / h1; and the speed adjustment amount corresponding to the flow rate per second △v03=-△h1 j ×v0 / h1; In order to avoid fluctuations in the inlet tension of the frame caused by the adjustment of the S-roll speed, it is necessary to adjust the roll gap accordingly based on the measured tension difference at the inlet △T0=(T0-T0*), where T0 is the measured tension at the inlet and T0* is the set tension at the inlet. The adjustment is △s5=K1×△T0, where K1 is the efficiency coefficient of tension and roll gap, provided by the L2 model system.

[0023] During reverse rolling ( Figure 4 After the exit S-roll rotates 180° and forms a winding with the strip, it is put into production. The inlet S-roll is not put into operation, and its lower roll is used as a steering roll. The exit coiler is changed from direct tension control to indirect tension control. At this time, the advanced AGC mode is adopted, which adds speed AGC and exit tension roll gap control on the basis of conventional AGC. The corresponding adjustment calculation method is similar to that of forward rolling.

[0024] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0025] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thickness control method for a single-stand reversible cold rolling mill, wherein the single-stand reversible cold rolling mill unit includes an inlet coiler, an outlet coiler, a mill body, a mill hydraulic system, an inlet thickness gauge, an outlet thickness gauge, an inlet speed gauge, an outlet speed gauge, an inlet tension gauge, and an outlet tension gauge, characterized in that: The single-stand reversible cold rolling mill also includes S-rolls. S-rolls are installed at both the inlet and outlet of the mill. These S-rolls can rotate 180°, with the upper roll rotating to the lower roll position and the lower roll rotating to the upper roll position. This 180° rotation causes the strip to wind in an S-shape on the S-roll. The metal flow rate into the roll gap is controlled by adjusting the speed of the inlet S-roll to eliminate strip thickness variations. During forward rolling, the inlet S-roll rotates 180° to wind with the strip before being put into operation; the outlet S-roll is not used, and its lower roll is used as a guide roll. The inlet coiler uses indirect tension control. During reverse rolling, the outlet S-roll rotates 180° to wind with the strip before being put into operation; the inlet S-roll is not used, and its lower roll is used as a guide roll. The coiler uses indirect tension control. During forward rolling, the inlet S-roll speed adjustment is Δv0 = Δv01 + Δv02 + Δv03. The speed adjustment corresponding to the feedforward inlet thickness difference is Δv01 = -Δh0 × v0 / h0, where Δh0 is the inlet thickness deviation measured by the feedforward AGC using the inlet thickness gauge, v0 is the actual inlet speed of the strip measured by the inlet speed gauge, and h0 is the actual inlet thickness measured by the inlet thickness gauge. The speed adjustment corresponding to monitoring is Δv02 = -Δh1 × v0 / h1, where Δh1 is the outlet thickness deviation measured by the monitoring AGC using the outlet thickness gauge, h1 is the actual outlet strip thickness measured by the outlet thickness gauge, and v0 is the actual inlet speed measured by the inlet speed gauge. The speed adjustment corresponding to the flow rate is Δv03 = -Δh1. j ×v0 / h1,△h1 j For the exit thickness deviation, h1 is the actual exit strip thickness measured by the exit thickness gauge, and v0 is the actual entry speed of the strip measured by the entry speed gauge. In order to avoid the fluctuation of the frame entry tension caused by the adjustment of the S-roll speed, it is necessary to adjust the roll gap accordingly based on the actual tension difference at the entry ΔT0=(T0-T0*), where T0 is the actual tension at the entry and T0* is the set tension at the entry. Δs5=K1×ΔT0, where K1 is the efficiency coefficient of tension and roll gap.

2. The thickness control method for a single-stand reversible cold rolling mill as described in claim 1, characterized in that: The S-roller is equipped with a motor drive.

3. The thickness control method for a single-stand reversible cold rolling mill as described in claim 2, characterized in that: A speed AGC module and a tension roll gap control model are added to the unit's PLC control program. The S-roller is the adjustment actuator of the speed AGC module.

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