A hydraulic circuit and control method for realizing rapid action of AGC cylinder of rolling mill

Abstract

A hydraulic circuit and control method for achieving rapid actuation of an AGC cylinder in a rolling mill, comprising first to fifth check valves, first to fourth servo valves, first to second hydraulically controlled check valves, a solenoid reversing valve, and first to second displacement sensors. The method comprises the following steps: before the hydraulic pump station is started, the control signals of the first to fourth servo valves are set to 0, and the solenoid reversing valve is de-energized. Upon startup of the hydraulic pump station, the oil source pressure Ps increases. When Ps exceeds 5 MPa, the first servo valve and displacement sensor, along with the operating-side AGC cylinder engagement position, close the loop and control the piston of the operating-side AGC cylinder to retract to 2 mm from its highest position. The third servo valve, second displacement sensor, and transmission-side AGC cylinder operate similarly. The control signals of the second and fourth servo valves remain 0, and the solenoid reversing valve remains de-energized. After Ps reaches the system's rated operating pressure, the first and third servo valves are used to control the roll gap to a preset position. The motion displacement curves of the operating-side and transmission-side AGC cylinders are set, and the rolling mill is put into operation in the set operating mode.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic control, and in particular relates to a hydraulic circuit for realizing rapid action of an AGC oil cylinder of a rolling mill and a control method thereof. Background Art

[0002] For the hydraulic AGC control process of conventional constant thickness rolling, generally only the load pressing speed of the AGC cylinder is paid attention to, while the flow rate required for the working process of the AGC cylinder is relatively large. When a single servo valve cannot meet the flow demand, when the frequency response speed of the large flow servo valve is low, and when the cost of the high frequency response large flow servo valve is high, a servo valve is usually used. Figure 1 The conventional hydraulic circuit with two servo valves in parallel is shown.

[0003] In recent years, during hot rolling flat shape control and cold rolling differential plate rolling, it has been found that the conventional hydraulic circuit with two parallel servo valves and its control method can meet the requirements for the AGC cylinder's pressing speed. However, the AGC cylinder's retraction speed achieved by this control method is sometimes too low (especially when the rolling force is small). Therefore, the target shape of the rolled piece can only be achieved by reducing the rolling speed. The specific reasons for this are:

[0004] ①. The servo valve inlet pressure (i.e., oil source pressure) Ps is relatively high (≥21MPa). When the AGC cylinder needs to be pressed down, a positive control signal needs to be sent to the servo valve to connect the servo valve P port with the A port. The valve opening is determined by the size of the control signal. At this time, the pressure difference between the servo valve inlet pressure Ps and the AGC cylinder rodless chamber pressure P1 is relatively large, so the flow required for the AGC cylinder to be pressed down can be generated.

[0005] ② When the AGC cylinder needs to retract, a negative control signal needs to be sent to the servo valve to connect the servo valve A port and T port, and the cylinder can retract under the action of the rod chamber back pressure.

[0006] Through intuitive analysis, it can be seen that when the cylinder speed reaches a steady state, P0×S2+Fz=P1×S1 (where Fz is the rolling force, S2 is the annular area of ​​the rod cavity of the AGC cylinder, S1 is the piston area of ​​the rodless cavity of the AGC cylinder, and P0 is the back pressure, which is generally between 3-5MPa); since S1 is usually more than twice that of S2, when Fz is small, P1 will be relatively small, and P1 is the pressure difference of the return oil from port A to port T of the servo valve (ignoring the back pressure of port T); in addition, the area gradient from port P to port A when the servo valve is working in the positive direction is equal to the area gradient from port A to port T when the servo valve is working in the negative direction, which results in the AGC cylinder retraction speed being significantly lower than its depression speed under the same servo valve opening size.

[0007] Currently, to increase the retraction speed of the AGC cylinder in a conventional hydraulic circuit with two parallel servo valves, the rod chamber backpressure (P0) is often increased. However, given that the flow rate through the servo valve is proportional to the square root of the pressure differential across the servo valve, assuming other conditions are met, increasing the P0 by at least four times (ignoring Fz) to 12-20 MPa or higher is necessary to double the cylinder retraction speed. Such high backpressures would result in unacceptable rolling force losses during the reduction process. While a proportional pressure reducing valve could be installed in the backpressure circuit to achieve graded control of the backpressure (P0) during the AGC reduction and retraction processes, the proportional valve's slow frequency response significantly negatively impacts the mill's roll gap control during the high-low pressure switching process. Therefore, the conventional hydraulic circuit with two parallel servo valves and its control method struggle to simultaneously achieve both rapid reduction and retraction of the AGC cylinder. Summary of the Invention

[0008] In response to the problems existing in the prior art, the present invention provides a hydraulic circuit and a control method for realizing rapid movement of the AGC cylinder of a rolling mill. The hydraulic circuit is suitable for hot rolling flat plate shape control, cold rolling differential thickness plate rolling, and other occasions where high requirements are placed on the load-carrying pressing speed and retraction speed of the AGC cylinder. The circuit can ensure the rapid load-carrying pressing function of the AGC cylinder and realize the rapid retraction function of the AGC cylinder at the same time, effectively meeting the process requirements of hot rolling flat plate shape control or cold rolling differential thickness plate rolling.

[0009] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a hydraulic circuit for realizing the rapid action of the AGC oil cylinder of a rolling mill, comprising a first servo valve, a second servo valve, a third servo valve, a fourth servo valve and an electromagnetic reversing valve; the inlet of the first servo valve, the inlet of the second servo valve, the inlet of the third servo valve, the inlet of the fourth servo valve and the inlet of the electromagnetic reversing valve are all connected to the oil supply port of the hydraulic AGC system; the oil return port of the first servo valve, the oil return port of the second servo valve, the oil return port of the third servo valve, the oil return port of the fourth servo valve and the oil return port of the electromagnetic reversing valve are all connected to the oil supply port of the hydraulic AGC system The return oil port of the AGC system is connected; the first working oil port of the first servo valve and the first working oil port of the second servo valve are both connected to the rodless chamber of the AGC cylinder on the operating side; the second working oil port of the first servo valve and the second working oil port of the second servo valve are both connected to the rod chamber of the AGC cylinder on the operating side; the first working oil port of the third servo valve and the first working oil port of the fourth servo valve are both connected to the rodless chamber of the AGC cylinder on the transmission side; the second working oil port of the third servo valve and the second working oil port of the fourth servo valve are both connected to the rod chamber of the AGC cylinder on the transmission side.

[0010] A first hydraulically controlled one-way valve is arranged on the pipeline between the second working oil port of the second servo valve and the rod chamber of the AGC cylinder on the operating side; the outlet of the first hydraulically controlled one-way valve is connected to the second working oil port of the second servo valve, the inlet of the first hydraulically controlled one-way valve is connected to the rod chamber of the AGC cylinder on the operating side, and the control port of the first hydraulically controlled one-way valve is connected to the second working oil port of the electromagnetic reversing valve.

[0011] A second hydraulically controlled one-way valve is arranged on the pipeline between the second working oil port of the fourth servo valve and the rod chamber of the transmission side AGC cylinder; the outlet of the second hydraulically controlled one-way valve is connected to the second working oil port of the fourth servo valve, the inlet of the second hydraulically controlled one-way valve is connected to the rod chamber of the transmission side AGC cylinder, and the control port of the second hydraulically controlled one-way valve is connected to the second working oil port of the electromagnetic reversing valve.

[0012] A first one-way valve is provided on the pipeline between the oil return port of the first servo valve and the oil return port of the AGC system, the inlet of the first one-way valve is connected to the oil return port of the first servo valve, and the outlet of the first one-way valve is connected to the oil return port of the AGC system; a second one-way valve is provided on the pipeline between the oil return port of the second servo valve and the oil return port of the AGC system, the inlet of the second one-way valve is connected to the oil return port of the second servo valve, and the outlet of the second one-way valve is connected to the oil return port of the AGC system; a third one-way valve is provided on the pipeline between the oil return port of the third servo valve and the oil return port of the AGC system, The inlet of the reversing valve is connected with the oil return port of the third servo valve, and the outlet of the third one-way valve is connected with the oil return port of the AGC system; a fourth one-way valve is provided on the pipeline between the oil return port of the fourth servo valve and the oil return port of the AGC system, the inlet of the fourth one-way valve is connected with the oil return port of the fourth servo valve, and the outlet of the fourth one-way valve is connected with the oil return port of the AGC system; a fifth one-way valve is provided on the pipeline between the oil return port of the electromagnetic reversing valve and the oil return port of the AGC system, the inlet of the fifth one-way valve is connected with the oil return port of the electromagnetic reversing valve, and the outlet of the fifth one-way valve is connected with the oil return port of the AGC system.

[0013] A first oil pressure sensor is provided on the direct-connected pipeline of the oil supply port of the hydraulic AGC system; a second oil pressure sensor is provided on the direct-connected pipeline of the rodless chamber of the operating side AGC cylinder; a third oil pressure sensor is provided on the direct-connected pipeline of the rod chamber of the operating side AGC cylinder; a fourth oil pressure sensor is provided on the direct-connected pipeline of the rodless chamber of the transmission side AGC cylinder; and a fifth oil pressure sensor is provided on the direct-connected pipeline of the rod chamber of the transmission side AGC cylinder.

[0014] The operating-side AGC oil cylinder is equipped with a first displacement sensor; the transmission-side AGC oil cylinder is equipped with a second displacement sensor.

[0015] The control method of the hydraulic circuit for realizing the rapid action of the AGC oil cylinder of the rolling mill comprises the following steps:

[0016] Step 1: Before the hydraulic pump station of the AGC system is started, the control signals of the first servo valve, the second servo valve, the third servo valve and the fourth servo valve are all 0, and the electromagnetic reversing valve is in the power-off state;

[0017] Step 2: Start the hydraulic pump station of the AGC system, and the oil source pressure Ps of the AGC system begins to increase. When Ps>5MPa, the first servo valve, the first displacement sensor and the operating side AGC cylinder are put into a closed loop position, and the operating side AGC cylinder piston is controlled to retract to 2mm from its highest position; at the same time, the third servo valve, the second displacement sensor and the transmission side AGC cylinder are put into a closed loop position, and the transmission side AGC cylinder piston is controlled to retract to 2mm from its highest position; wherein, the control signals of the second servo valve and the fourth servo valve continue to remain at 0, and the electromagnetic reversing valve continues to be in the power-off state;

[0018] Step 3: After the oil source pressure Ps of the AGC system reaches the rated working pressure of the system, the first servo valve and the third servo valve are used to control the roll gap to a preset position to prepare for steel rolling;

[0019] Step 4: Set the motion displacement curves of the operating side AGC cylinder and the transmission side AGC cylinder according to the rolling process;

[0020] Step 5: The rolling mill starts rolling, and the first servo valve, the second servo valve, the third servo valve and the fourth servo valve are put into operation at the same time under the set working mode.

[0021] In step 5, there are two working modes: (1) the electromagnetic reversing valve is always in the power-off state, and (2) the electromagnetic reversing valve is always in the power-on state. The working methods of each servo valve in the two working modes are the same, as follows:

[0022] ①. During the roll gap reduction process, the PI controller calculates the control quantity u11 based on the difference between the set displacement and the actual displacement of the AGC cylinder on the operating side and outputs it to the first servo valve. The control quantity Cz·u11 is sent to the second servo valve, where Cz is the adjustment coefficient, Cz∈[0,1]. Cz is set according to the maximum movement speed requirement of the AGC cylinder. The higher the required maximum movement speed, the larger the Cz value. Similarly, the PI controller calculates the control quantity u12 based on the difference between the set displacement and the actual displacement of the AGC cylinder on the transmission side and outputs it to the third servo valve. The control quantity Cz·u12 is sent to the fourth servo valve.

[0023] ②. During the process of setting the constant roll gap, the set displacements of the operating-side AGC cylinder and the transmission-side AGC cylinder are constants. Based on the difference between the set displacement and the actual displacement of the operating-side AGC cylinder, the PI controller calculates the control output u21 and sends it to the first servo valve. The control output to the second servo valve is 0. Similarly, based on the difference between the set displacement and the actual displacement of the transmission-side AGC cylinder, the PI controller calculates the control output u22 and sends it to the third servo valve. The control output to the fourth servo valve is 0.

[0024] ③. During the roll gap increasing process, the PI controller calculates the control quantity output u31 based on the difference between the set displacement and the actual displacement of the AGC cylinder on the operating side and sends it to the first servo valve, and the control quantity sent to the second servo valve is Cz·u32; similarly, the PI controller calculates the control quantity output u32 based on the difference between the set displacement and the actual displacement of the AGC cylinder on the transmission side and sends it to the third servo valve, and the control quantity sent to the fourth servo valve is Cz·u32.

[0025] Beneficial effects of the present invention:

[0026] The hydraulic circuit and control method for realizing rapid movement of the AGC cylinder of the rolling mill of the present invention are suitable for occasions such as hot rolling flat plate shape control and cold rolling of differential thickness plate, which have high requirements for the load-carrying pressing speed and retraction speed of the AGC cylinder. It can not only ensure the rapid load-carrying pressing function of the AGC cylinder, but also realize the rapid retraction function of the AGC cylinder, effectively meeting the process requirements of hot rolling flat plate shape control or cold rolling of differential thickness plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the principle diagram of the hydraulic circuit of the traditional dual servo valves in parallel;

[0028] Figure 2 This is a schematic diagram of a hydraulic circuit for realizing rapid action of the AGC oil cylinder of a rolling mill according to the present invention;

[0029] Figure 3 Schematic diagram of the cross-sectional shape of the target periodically variable thickness plate in the embodiment;

[0030] In the figure, 1 is the first oil pressure sensor, 2 is the first one-way valve, 3 is the second one-way valve, 4 is the third one-way valve, 5 is the fourth one-way valve, 6 is the fifth one-way valve, 7 is the first servo valve, 8 is the second servo valve, 9 is the third servo valve, 10 is the fourth servo valve, 11 is the electromagnetic reversing valve, 12 is the first hydraulically controlled one-way valve, 13 is the second hydraulically controlled one-way valve, 14 is the second oil pressure sensor, 15 is the first displacement sensor, 16 is the second displacement sensor, 17 is the third oil pressure sensor, 18 is the fourth oil pressure sensor, 19 is the fifth oil pressure sensor, 20 is the operating side AGC cylinder, 21 is the transmission side AGC cylinder, P is the high pressure of the AGC system Pressure oil port, Ps—oil source pressure of AGC system, P0—back pressure, T—return oil port of AGC system, A2—inlet of first check valve, B2—outlet of first check valve, A3—inlet of second check valve, B3—outlet of second check valve, A4—inlet of third check valve, B4—outlet of third check valve, A5—inlet of fourth check valve, B5—outlet of fourth check valve, A6—inlet of fifth check valve, B6—outlet of fifth check valve, P7—inlet of first servo valve, T7—return oil port of first servo valve, A7—first working oil port of first servo valve, B7—second working oil port of first servo valve, P8 —The inlet of the second servo valve, T8—the return oil port of the second servo valve, A8—the first working oil port of the second servo valve, B8—the second working oil port of the second servo valve, P9—the inlet of the third servo valve, T9—the return oil port of the third servo valve, A9—the first working oil port of the third servo valve, B9—the second working oil port of the third servo valve, P10—the inlet of the fourth servo valve, T10—the return oil port of the fourth servo valve, A10—the first working oil port of the fourth servo valve, B10—the second working oil port of the fourth servo valve, T11—the return oil port of the electromagnetic reversing valve, P11—the inlet of the electromagnetic reversing valve, A11—the first working oil port of the electromagnetic reversing valve, B11—the second working oil port of the electromagnetic reversing valve, A12—the inlet of the first hydraulically controlled one-way valve, B12—the outlet of the first hydraulically controlled one-way valve, X12—the control port of the first hydraulically controlled one-way valve, A13—the inlet of the second hydraulically controlled one-way valve, B13—the outlet of the second hydraulically controlled one-way valve, X13—the control port of the second hydraulically controlled one-way valve, S1—the rodless chamber piston area of ​​the AGC cylinder, S2—the annular area of ​​the rod chamber of the AGC cylinder, P11—the rodless chamber pressure of the AGC cylinder on the operating side, P12—the rod chamber pressure of the AGC cylinder on the operating side, P21—the rodless chamber pressure of the AGC cylinder on the transmission side, P22—the rod chamber pressure of the AGC cylinder on the transmission side. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] like Figure 2As shown in FIG, a hydraulic circuit for realizing rapid action of the AGC cylinder of a rolling mill comprises a first servo valve 7, a second servo valve 8, a third servo valve 9, a fourth servo valve 10 and an electromagnetic reversing valve 11; the inlet P7 of the first servo valve 7, the inlet P8 of the second servo valve 8, the inlet P9 of the third servo valve 9, the inlet P10 of the fourth servo valve 10 and the inlet P11 of the electromagnetic reversing valve 11 are all connected to the oil supply port P of the hydraulic AGC system; the oil return port T7 of the first servo valve 7, the oil return port T8 of the second servo valve 8, the oil return port T9 of the third servo valve 9, the oil return port T10 of the fourth servo valve 10 and the oil return port T11 of the electromagnetic reversing valve 11 are all connected to the oil supply port P of the AGC system The return oil port T of the system is connected; the first working oil port A7 of the first servo valve 7 and the first working oil port A8 of the second servo valve 8 are both connected to the rodless cavity of the operating side AGC cylinder 20; the second working oil port B7 of the first servo valve 7 and the second working oil port B8 of the second servo valve 8 are both connected to the rod cavity of the operating side AGC cylinder 20; the first working oil port A9 of the third servo valve 9 and the first working oil port A10 of the fourth servo valve 10 are both connected to the rodless cavity of the transmission side AGC cylinder 21; the second working oil port B9 of the third servo valve 9 and the second working oil port B10 of the fourth servo valve 10 are both connected to the rod cavity of the transmission side AGC cylinder 21.

[0033] A first hydraulically controlled one-way valve 12 is arranged on the pipeline between the second working oil port B8 of the second servo valve 8 and the rod chamber of the operating side AGC cylinder 20; the outlet B12 of the first hydraulically controlled one-way valve 12 is connected to the second working oil port B8 of the second servo valve 8, the inlet A12 of the first hydraulically controlled one-way valve 12 is connected to the rod chamber of the operating side AGC cylinder 20, and the control port X12 of the first hydraulically controlled one-way valve 12 is connected to the second working oil port B11 of the electromagnetic reversing valve 11.

[0034] A second hydraulically controlled one-way valve 13 is provided on the pipeline between the second working oil port B10 of the fourth servo valve 10 and the rod chamber of the transmission side AGC cylinder 21; the outlet B13 of the second hydraulically controlled one-way valve 13 is connected to the second working oil port B10 of the fourth servo valve 10, the inlet A13 of the second hydraulically controlled one-way valve 13 is connected to the rod chamber of the transmission side AGC cylinder 21, and the control port X13 of the second hydraulically controlled one-way valve 13 is connected to the second working oil port B11 of the electromagnetic reversing valve 11.

[0035] A first one-way valve 2 is provided on the pipeline between the oil return port T7 of the first servo valve 7 and the oil return port T of the AGC system, and the inlet A2 of the first one-way valve 2 is connected to the oil return port T7 of the first servo valve 7, and the outlet B2 of the first one-way valve 2 is connected to the oil return port T of the AGC system; a second one-way valve 3 is provided on the pipeline between the oil return port T8 of the second servo valve 8 and the oil return port T of the AGC system, and the inlet A3 of the second one-way valve 3 is connected to the oil return port T8 of the second servo valve 8, and the outlet B3 of the second one-way valve 3 is connected to the oil return port T of the AGC system; a third one-way valve 4 is provided on the pipeline between the oil return port T9 of the third servo valve 9 and the oil return port T of the AGC system, and the inlet A3 of the third one-way valve 4 is connected to the oil return port T of the AGC system. 4 is connected to the oil return port T9 of the third servo valve 9, and the outlet B4 of the third check valve 4 is connected to the oil return port T of the AGC system; a fourth check valve 5 is provided on the pipeline between the oil return port T10 of the fourth servo valve 10 and the oil return port T of the AGC system, the inlet A5 of the fourth check valve 5 is connected to the oil return port T10 of the fourth servo valve 10, and the outlet B5 of the fourth check valve 5 is connected to the oil return port T of the AGC system; a fifth check valve 6 is provided on the pipeline between the oil return port T11 of the solenoid reversing valve 11 and the oil return port T of the AGC system, the inlet A6 of the fifth check valve 6 is connected to the oil return port T11 of the solenoid reversing valve 11, and the outlet B6 of the fifth check valve 6 is connected to the oil return port T of the AGC system.

[0036] A first oil pressure sensor 1 is provided on the direct-connected pipeline of the hydraulic AGC system oil supply port P; a second oil pressure sensor 14 is provided on the direct-connected pipeline of the rodless cavity of the operating side AGC cylinder 20; a third oil pressure sensor 17 is provided on the direct-connected pipeline of the rod cavity of the operating side AGC cylinder 20; a fourth oil pressure sensor 18 is provided on the direct-connected pipeline of the rodless cavity of the transmission side AGC cylinder 21; and a fifth oil pressure sensor 19 is provided on the direct-connected pipeline of the rod cavity of the transmission side AGC cylinder 21.

[0037] The operating-side AGC cylinder 20 is equipped with a first displacement sensor 15 ; the transmission-side AGC cylinder 21 is equipped with a second displacement sensor 16 .

[0038] In this embodiment, the model of the first oil pressure sensor 1, the second oil pressure sensor 14, the third oil pressure sensor 17, the fourth oil pressure sensor 18 and the fifth oil pressure sensor 19 are all HDA3844-A-400-000 (range is 40 MPa), the model of the first check valve 2, the second check valve 3, the third check valve 4 and the fourth check valve 5 are all M-SR10KE05-10B, the model of the fifth check valve 6 is Z1S6T1-30B, the model of the first servo valve 7, the second servo valve 8, the third servo valve 9 and the fourth servo valve 10 are all G761-3004 (Q N=38L / min,△P N =7MPa), the model of the solenoid reversing valve 11 is 4WE6D61B / CG24N9Z5L, the models of the first hydraulically controlled one-way valve 12 and the second hydraulically controlled one-way valve 13 are both SV10PA2-40B, and the models of the first displacement sensor 15 and the second displacement sensor 16 are both RH5MA0080M01P051S1011G9 (range 80mm).

[0039] In this embodiment, the rolling mill uses a 350mm coiling type four-roll reversible cold rolling mill, with a working roll diameter of 200mm, a working roll width of 370mm, a support roll diameter of 480mm, a support roll width of 350mm, a maximum rolling force of 400t, an AGC oil cylinder piston diameter D of 400mm, an AGC oil cylinder piston rod diameter d of 320mm, an AGC oil cylinder stroke of 50mm, an AGC system oil source pressure Ps of 21MPa, a raw material of Q235 strip steel with a width of 200mm and a thickness of 2mm, a front tension of 15kN, a rear tension of 25kN, and a rolling speed of 1.2m / s. Figure 3 As shown in the figure, the cross-sectional shape of the target periodically variable thickness plate is shown. The retraction speed of the AGC cylinder in the BC section needs to reach 10.8 mm / s. The maximum rolling force required during the rolling process is about 865 kN, and the minimum rolling force is about 300 kN.

[0040] The control method of the hydraulic circuit for realizing the rapid action of the AGC oil cylinder of the rolling mill comprises the following steps:

[0041] Step 1: Before the hydraulic pump station of the AGC system is started, the control signals of the first servo valve 7, the second servo valve 8, the third servo valve 9 and the fourth servo valve 10 are all 0, and the electromagnetic reversing valve 11 is in the power-off state;

[0042] Step 2: Start the hydraulic pump station of the AGC system, and the oil source pressure Ps of the AGC system begins to increase. When Ps>5MPa, the first servo valve 7, the first displacement sensor 15 and the operating side AGC cylinder are closed in the loop, and the operating side AGC cylinder piston is controlled to retract to 2mm from its highest position; at the same time, the third servo valve 9, the second displacement sensor 16 and the transmission side AGC cylinder are closed in the loop, and the transmission side AGC cylinder piston is controlled to retract to 2mm from its highest position; wherein, the control signals of the second servo valve 8 and the fourth servo valve 10 continue to remain at 0, and the electromagnetic reversing valve 11 continues to be in the power-off state;

[0043] Step 3: After the oil source pressure Ps of the AGC system reaches the rated working pressure of the system, the first servo valve 7 and the third servo valve 9 are used to control the roll gap to a preset position (so that the plate outlet thickness is 1.9 mm) to prepare for steel rolling;

[0044] Step 4: Set the motion displacement curves of the operating side AGC cylinder and the transmission side AGC cylinder according to the rolling process;

[0045] Step 5: The rolling mill starts rolling, and the first servo valve 7, the second servo valve 8, the third servo valve 9 and the fourth servo valve 10 are put into operation at the same time under the set working mode.

[0046] In step 5, there are two working modes: (1) the electromagnetic reversing valve 11 is always in the power-off state, and (2) the electromagnetic reversing valve 11 is always in the power-on state. The working methods of the servo valves in the two working modes are the same, as follows:

[0047] ①, in the process of setting the roller gap reduction ( Figure 3 In the DE section of the figure, according to the difference between the set displacement and the actual displacement of the AGC cylinder on the operating side, the PI controller calculates the control quantity u11 and outputs it to the first servo valve 7. The control quantity Cz·u11 is sent to the second servo valve 8, where Cz is the adjustment coefficient, Cz∈[0,1]. Cz is set according to the maximum movement speed requirement of the AGC cylinder, and the higher the required maximum movement speed, the larger the value of Cz. Similarly, according to the difference between the set displacement and the actual displacement of the AGC cylinder on the transmission side, the PI controller calculates the control quantity u12 and outputs it to the third servo valve 9. The control quantity Cz·u12 is sent to the fourth servo valve 10.

[0048] ②, During the process of setting the constant roll gap ( Figure 3 The set displacements of the operating-side AGC cylinder and the transmission-side AGC cylinder are constants. The PI controller calculates the control quantity output u21 based on the difference between the set displacement and the actual displacement of the operating-side AGC cylinder and sends it to the first servo valve 7. The control quantity sent to the second servo valve 8 is 0. Similarly, the PI controller calculates the control quantity output u22 based on the difference between the set displacement and the actual displacement of the transmission-side AGC cylinder and sends it to the third servo valve 9. The control quantity sent to the fourth servo valve 10 is 0.

[0049] ③、During the process of increasing the roller gap ( Figure 3 BC section in the figure), according to the difference between the set displacement and the actual displacement of the AGC cylinder on the operating side, the PI controller calculates the control quantity output u31 and sends it to the first servo valve 7, and the control quantity sent to the second servo valve 8 is Cz·u32; similarly, according to the difference between the set displacement and the actual displacement of the AGC cylinder on the transmission side, the PI controller calculates the control quantity output u32 and sends it to the third servo valve 9, and the control quantity sent to the fourth servo valve 10 is Cz·u32.

[0050] It should be noted that although the working modes of the servo valves in working mode (1) and working mode (2) are the same, there are differences in their effects. The steady-state value of the retraction speed of the AGC cylinder in the retraction process in working mode (2) is slightly higher than that in working mode (1). The oil pressure in the rod chambers of the two AGC cylinders is high and fluctuates slightly (close to the oil source pressure Ps of the AGC system), which is conducive to improving the dynamic response speed of the closed-loop control of the AGC cylinder retraction path. In addition, when using working mode (2), since the oil pressure in the rod chambers of the two AGC cylinders during the pressing process is not high, when switching from the constant roll gap process stage to the roll gap increase process stage (near point B), the pressure shock in the rod chamber of the AGC cylinder will be significantly higher than when using working mode (1), which will be detrimental to the life of the seal of the AGC cylinder.

[0051] In order to better illustrate the technical advantages of the present invention, a comparative simulation study was conducted on the maximum pressing speed and retraction speed of the AGC oil cylinder under the conventional existing technology and the present invention. The simulation data are shown in Tables 1 to 3, as follows:

[0052] ①, Pressing process: 90% of the rated servo valve signal (denoted as u0) is sent to the first servo valve 7 and the third servo valve 9, and Cz·u0 (assuming Cz=1) is sent to the second servo valve 8 and the fourth servo valve 10 at the same time;

[0053] ②. Retraction process: Send the servo valve rated signal -u0 to the first servo valve 7 and the third servo valve 9, and send -Cz·u0 (take Cz=1) to the second servo valve 8 and the fourth servo valve 10.

[0054] Table 1. AGC cylinder pressing and retracting speed data under different rolling forces (traditional existing technology)

[0055]

[0056] Table 2. AGC cylinder compression and retraction speed data under different rolling forces (inventive method - working mode 1)

[0057]

[0058] Table 3. AGC cylinder compression and retraction speed data under different rolling forces (inventive working mode 2)

[0059]

[0060] It can be seen from Tables 1 to 3 that, compared with the conventional prior art, the present invention can achieve a slight increase in the AGC oil cylinder pressing speed during the mill roll gap reduction process; and can achieve a significant increase in the AGC oil cylinder retraction speed during the mill roll gap increase process.

[0061] It can also be seen from Table 1 that when the rolling speed is 1.2 m / s, within the rolling force range required in this embodiment (300-865 kN), the achievable AGC cylinder retraction speed under conventional existing technology cannot meet the process requirements, and the rolling speed of the rolling mill must be reduced to achieve the target periodic variable thickness plate shape.

[0062] It can also be seen from Tables 2 and 3 that within the rolling force range required in this embodiment (300-865 kN), the present invention can meet the process requirements, achieve a rolling speed of 1.2 m / s, and ensure high production efficiency of the rolling mill.

[0063] The solutions in the embodiments are not intended to limit the patent protection scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention is included in the patent scope of this case.

Claims

1. A hydraulic circuit for realizing rapid action of the AGC cylinder of a rolling mill, characterized by: It includes a first servo valve, a second servo valve, a third servo valve, a fourth servo valve and an electromagnetic reversing valve; the inlet of the first servo valve, the inlet of the second servo valve, the inlet of the third servo valve, the inlet of the fourth servo valve and the inlet of the electromagnetic reversing valve are all connected to the oil supply port of the hydraulic AGC system; the return oil port of the first servo valve, the return oil port of the second servo valve, the return oil port of the third servo valve, the return oil port of the fourth servo valve and the return oil port of the electromagnetic reversing valve are all connected to the return oil port of the AGC system; the first working oil port of the first servo valve and the first working oil port of the second servo valve are both connected to the rodless chamber of the operating side AGC cylinder; the second working oil port of the first servo valve and the second working oil port of the second servo valve are both connected to the rod chamber of the operating side AGC cylinder; the first working oil port of the third servo valve and the first working oil port of the fourth servo valve are both connected to the rodless chamber of the transmission side AGC cylinder; the second working oil port of the third servo valve and the second working oil port of the fourth servo valve are both connected to the rod chamber of the transmission side AGC cylinder.

2. A hydraulic circuit for realizing rapid action of an AGC cylinder of a rolling mill according to claim 1, characterized in that: A first hydraulically controlled one-way valve is arranged on the pipeline between the second working oil port of the second servo valve and the rod chamber of the AGC cylinder on the operating side; the outlet of the first hydraulically controlled one-way valve is connected to the second working oil port of the second servo valve, the inlet of the first hydraulically controlled one-way valve is connected to the rod chamber of the AGC cylinder on the operating side, and the control port of the first hydraulically controlled one-way valve is connected to the second working oil port of the electromagnetic reversing valve.

3. A hydraulic circuit for realizing rapid operation of an AGC cylinder of a rolling mill according to claim 2, characterized in that: A second hydraulically controlled one-way valve is arranged on the pipeline between the second working oil port of the fourth servo valve and the rod chamber of the transmission side AGC cylinder; the outlet of the second hydraulically controlled one-way valve is connected to the second working oil port of the fourth servo valve, the inlet of the second hydraulically controlled one-way valve is connected to the rod chamber of the transmission side AGC cylinder, and the control port of the second hydraulically controlled one-way valve is connected to the second working oil port of the electromagnetic reversing valve.

4. A hydraulic circuit for realizing rapid operation of an AGC cylinder of a rolling mill according to claim 3, characterized in that: A first one-way valve is provided on the pipeline between the oil return port of the first servo valve and the oil return port of the AGC system, the inlet of the first one-way valve is connected to the oil return port of the first servo valve, and the outlet of the first one-way valve is connected to the oil return port of the AGC system; a second one-way valve is provided on the pipeline between the oil return port of the second servo valve and the oil return port of the AGC system, the inlet of the second one-way valve is connected to the oil return port of the second servo valve, and the outlet of the second one-way valve is connected to the oil return port of the AGC system; a third one-way valve is provided on the pipeline between the oil return port of the third servo valve and the oil return port of the AGC system, The inlet of the reversing valve is connected with the oil return port of the third servo valve, and the outlet of the third one-way valve is connected with the oil return port of the AGC system; a fourth one-way valve is provided on the pipeline between the oil return port of the fourth servo valve and the oil return port of the AGC system, the inlet of the fourth one-way valve is connected with the oil return port of the fourth servo valve, and the outlet of the fourth one-way valve is connected with the oil return port of the AGC system; a fifth one-way valve is provided on the pipeline between the oil return port of the electromagnetic reversing valve and the oil return port of the AGC system, the inlet of the fifth one-way valve is connected with the oil return port of the electromagnetic reversing valve, and the outlet of the fifth one-way valve is connected with the oil return port of the AGC system.

5. The hydraulic circuit for realizing rapid operation of the AGC cylinder of a rolling mill according to claim 4, characterized in that: A first oil pressure sensor is provided on the direct-connected pipeline of the oil supply port of the hydraulic AGC system; a second oil pressure sensor is provided on the direct-connected pipeline of the rodless chamber of the operating side AGC cylinder; a third oil pressure sensor is provided on the direct-connected pipeline of the rod chamber of the operating side AGC cylinder; a fourth oil pressure sensor is provided on the direct-connected pipeline of the rodless chamber of the transmission side AGC cylinder; and a fifth oil pressure sensor is provided on the direct-connected pipeline of the rod chamber of the transmission side AGC cylinder.

6. A hydraulic circuit for realizing rapid operation of an AGC cylinder of a rolling mill according to claim 5, characterized in that: The operating-side AGC oil cylinder is equipped with a first displacement sensor; the transmission-side AGC oil cylinder is equipped with a second displacement sensor.

7. The method for controlling a hydraulic circuit for realizing rapid operation of an AGC cylinder of a rolling mill as claimed in claim 6, characterized in that: The steps include: Step 1: Before the hydraulic pump station of the AGC system is started, the control signals of the first servo valve, the second servo valve, the third servo valve and the fourth servo valve are all 0, and the electromagnetic reversing valve is in the power-off state; Step 2: Start the hydraulic pump station of the AGC system, and the oil source pressure Ps of the AGC system begins to increase. When Ps>5MPa, the first servo valve, the first displacement sensor and the operating side AGC cylinder are put into a closed loop position, and the operating side AGC cylinder piston is controlled to retract to 2mm from its highest position; at the same time, the third servo valve, the second displacement sensor and the transmission side AGC cylinder are put into a closed loop position, and the transmission side AGC cylinder piston is controlled to retract to 2mm from its highest position; wherein, the control signals of the second servo valve and the fourth servo valve continue to remain at 0, and the electromagnetic reversing valve continues to be in the power-off state; Step 3: After the oil source pressure Ps of the AGC system reaches the rated working pressure of the system, the first servo valve and the third servo valve are used to control the roll gap to a preset position to prepare for steel rolling; Step 4: Set the motion displacement curves of the operating side AGC cylinder and the transmission side AGC cylinder according to the rolling process; Step 5: The rolling mill starts rolling, and the first servo valve, the second servo valve, the third servo valve and the fourth servo valve are put into operation at the same time under the set working mode.

8. The method for controlling a hydraulic circuit for realizing rapid operation of an AGC cylinder of a rolling mill according to claim 7, characterized in that: In step 5, there are two working modes: (1) the electromagnetic reversing valve is always in the power-off state, and (2) the electromagnetic reversing valve is always in the power-on state. The working methods of each servo valve in the two working modes are the same, as follows: ①. During the roll gap reduction process, the PI controller calculates the control quantity u11 based on the difference between the set displacement and the actual displacement of the AGC cylinder on the operating side and outputs it to the first servo valve. The control quantity Cz·u11 is sent to the second servo valve, where Cz is the adjustment coefficient, Cz∈[0,1]. Cz is set according to the maximum movement speed requirement of the AGC cylinder. The higher the required maximum movement speed, the larger the Cz value. Similarly, the PI controller calculates the control quantity u12 based on the difference between the set displacement and the actual displacement of the AGC cylinder on the transmission side and outputs it to the third servo valve. The control quantity Cz·u12 is sent to the fourth servo valve. ②. During the process of setting the constant roll gap, the set displacements of the operating-side AGC cylinder and the transmission-side AGC cylinder are constants. Based on the difference between the set displacement and the actual displacement of the operating-side AGC cylinder, the PI controller calculates the control output u21 and sends it to the first servo valve. The control output to the second servo valve is 0. Similarly, based on the difference between the set displacement and the actual displacement of the transmission-side AGC cylinder, the PI controller calculates the control output u22 and sends it to the third servo valve. The control output to the fourth servo valve is 0. ③. During the roll gap increasing process, the PI controller calculates the control quantity output u31 based on the difference between the set displacement and the actual displacement of the AGC cylinder on the operating side and sends it to the first servo valve, and the control quantity sent to the second servo valve is Cz·u32; similarly, the PI controller calculates the control quantity output u32 based on the difference between the set displacement and the actual displacement of the AGC cylinder on the transmission side and sends it to the third servo valve, and the control quantity sent to the fourth servo valve is Cz·u32.

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