A control method for an ultra-high pressure boosting system of a hydraulic press

Abstract

The present invention relates to a control method for an ultra-high pressure boosting system of a hydraulic press, and the hardware system mainly includes: a first pressure sensor; a boosting cylinder; a displacement sensor; a second pressure sensor; a servo valve; a controller for collecting signals from the first pressure sensor, the displacement sensor, the second pressure sensor, and the third pressure sensor, executing control calculations, and transmitting control command signals to the servo valve; a constant pressure oil source for providing hydraulic oil medium and keeping the rated pressure of the system constant; a first one-way valve for isolating the cavity connected to the P port of the servo valve from other cavities in the hydraulic circuit in one direction; a second one-way valve; a third pressure sensor; and an actuator cylinder for driving the hydraulic press. Advantages: Constructing an automatic control method for boosting pressure with the piston displacement of a hydraulic boosting cylinder as an auxiliary observation state, solving the problem of boosting cylinder pressure control caused by the slow response of the hydraulic pressure sensor and the susceptibility of the signal to interference.

Description

Technical Field

[0001] The invention relates to a control method for an ultra-high pressure boosting system, in particular to a control method for an ultra-high pressure boosting system of a hydraulic press. Background Art

[0002] The ultra-high pressure boosting system can be used for multi-stage amplification of the hydraulic system pressure of the hydraulic press. The traditional hydraulic boosting system only uses the signal fed back by the pressure sensor for closed-loop control of the boosting pressure. However, the signal of the conventional pressure sensor is analog and has a slow detection response. It is difficult for the controller to perform dynamic differential calculations of the pressure signal, which seriously restricts the design of the dynamic control algorithm of the pressure, and thus affects the improvement of the performance of the ultra-high pressure hydraulic press. How to improve the dynamic pressure control algorithm of the hydraulic boosting system is a difficult problem that needs to be solved in the automatic control of the ultra-high pressure hydraulic press. Summary of the invention

[0003] The object of the present invention is to provide a control method for an ultra-high pressure boosting system of a hydraulic press, which can improve the dynamic response capability of the hydraulic boosting system pressure, thereby enhancing the automatic control performance of the ultra-high pressure hydraulic press.

[0004] The technical solution of the present invention is as follows:

[0005] The hardware system of the present invention at least includes:

[0006] The first pressure sensor is used to detect the pressure of the booster chamber of the booster cylinder p C ;

[0007] The booster cylinder is used to increase the pressure of the actuator cylinder chamber to above the rated pressure of the constant pressure oil source. The effective area of ​​the booster cylinder chamber is A C ;

[0008] Displacement sensor, used to detect the displacement of the booster cylinder piston s ;

[0009] The second pressure sensor is used to detect the pressure of the right working chamber of the booster cylinder. p A ;

[0010] The servo valve is used to control the movement of the booster cylinder piston. The control command signal of the servo valve is u v ;

[0011] A controller, used to collect signals from the first pressure sensor, the displacement sensor, the second pressure sensor, and the third pressure sensor, perform control calculations, and transmit control command signals to the servo valve;

[0012] Constant pressure oil source, used to provide hydraulic oil medium and keep the system rated pressure constant;

[0013] The first one-way valve is used to one-way isolate the cavity connected to the servo valve P port from other cavities in the hydraulic circuit;

[0014] The second one-way valve is used to one-way isolate the chamber connected to the boosting chamber of the boosting cylinder from other chambers in the hydraulic circuit;

[0015] The third pressure sensor is used to detect the pressure of the left working chamber of the booster cylinder. p B ;

[0016] The actuator cylinder is used to drive the motion mechanism of the hydraulic press. The piston displacement of the actuator cylinder is s a The effective area is A a .

[0017] Among them: the booster chamber of the booster cylinder is connected with the first pressure sensor oil port, the second one-way valve oil outlet, and the action chamber of the actuator cylinder. The volume of the connected chamber is V ; The piston of the booster cylinder and the detection end of the displacement sensor belong to the same assembly; the right working chamber of the booster cylinder is connected to the oil port of the second pressure sensor and the A port of the servo valve; the left working chamber of the booster cylinder is connected to the oil port of the third pressure sensor and the B port of the servo valve; the P port of the servo valve is connected to the oil outlet of the first check valve; the T port of the servo valve is connected to the hydraulic oil tank; the constant pressure oil source port is connected to the oil inlet of the first check valve and the second check valve; the controller is electrically connected to the first pressure sensor, the displacement sensor, the second pressure sensor, the servo valve and the third pressure sensor.

[0018] A control method for an ultra-high pressure boosting system of a hydraulic press, characterized in that:

[0019] At least the following steps are included:

[0020] Step 1: Plan the pressure expectations of the actuator cylinder action chamber and the booster cylinder booster chamber. p d ; Set the displacement error threshold e t As a control switching point, e t It is a positive number and is related to the efficiency of the boost cylinder.

[0021] Step 2: According to p d Calculate the ideal desired displacement of the booster cylinder piston s d , the calculation formula is:

[0022] ;

[0023] Where:E is the bulk modulus of hydraulic oil. V=V 0 −A c ×s+A a ×s a , V 0 yes V The initial value of .

[0024] Step 3: The controller compares the displacement error ( s d −s ) and the absolute value of e t The size of when | s d −s |> e t When , the control command signal expression of the servo valve is:

[0025] u v =u vs =f s ( s d −s );

[0026] u vs It is an auxiliary control instruction based on the displacement state of the boost cylinder piston.

[0027] f s ( s d −s ) is any value that can make the displacement error ( s d −s ) is a control function whose absolute value approaches 0. f s ( s d −s ) is a dynamic fast response control, which contains the displacement variable s d , s Differential calculation of .

[0028] Step 4: When | s d −s |≤ e t , the controller calculates the following two values:

[0029] u vp =f p ( p d −p C );

[0030] u vst =f s ( e t );

[0031] u vp It is a direct control instruction based on the pressure state of the booster chamber of the booster cylinder.

[0032] Controller Comparison u vp and u vst The absolute value of the servo valve is used as the control command signal of the servo valve. u v .

[0033] f p ( p d −p C ) is any value that can make the pressure error ( p d −p C ) is a control function whose absolute value approaches 0. f p ( p d −p C ) is a static precise control, without the need to adjust the pressure variable p d , p C Perform differential calculations to avoid the computational difficulties caused by signal interference.

[0034] With the help of s Can be carried out p C Dynamic estimation calculation, the calculation formula is:

[0035] ;

[0036] Where: E is the bulk modulus of hydraulic oil. V=V0 −A c ×s+A a ×s a , V 0 yes V The initial value of .

[0037] The controller uses the command signal u v Control servo valve.

[0038] The beneficial effects of the present invention are as follows:

[0039] The present invention uses the piston displacement of the hydraulic booster cylinder as an auxiliary observation state and does not completely rely on the pressure sensor signal in the dynamic control design, so that the relevant differential calculations can be completed in a conventional controller, thereby improving the automatic pressure control algorithm of the booster system. At the same time, the minimum absolute value algorithm ensures a smooth control switching process and effectively improves the pressure control performance of the ultra-high pressure hydraulic press. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a system principle diagram of the present invention.

[0041] Figure 2 It is a control structure diagram of the present invention.

[0042] Figure 1 In: 1-first pressure sensor, 2-boosting cylinder, 3-displacement sensor, 4-second pressure sensor, 5-servo valve, 6-controller, 7-constant pressure oil source, 8-first one-way valve, 9-second one-way valve, 10-third pressure sensor, 11-actuator cylinder. DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with the accompanying drawings.

[0044] See also Figure 1 , the hardware system of the present invention at least includes:

[0045] The first pressure sensor 1 is used to detect the pressure of the boost chamber of the boost cylinder 2 p C ;

[0046] The booster cylinder 2 is used to increase the pressure of the action chamber of the actuator cylinder 11 to above the rated pressure of the constant pressure oil source 7. The action area of ​​the booster chamber of the booster cylinder 2 is A C ;

[0047] Displacement sensor 3, used to detect the displacement of the piston of booster cylinder 2 s ;

[0048] The second pressure sensor 4 is used to detect the pressure of the right working chamber of the booster cylinder 2 p A ;

[0049] The servo valve 5 is used to control the movement of the piston of the booster cylinder 2. The control command signal of the servo valve 5 is u v ;

[0050] The controller 6 is used to collect signals from the first pressure sensor 1, the displacement sensor 3, the second pressure sensor 4, and the third pressure sensor 10, perform control calculations, and transmit control command signals to the servo valve 5;

[0051] A constant pressure oil source 7, used for providing hydraulic oil medium and maintaining a constant rated pressure of the system;

[0052] The first one-way valve 8 is used to one-way isolate the cavity connected to the P port of the servo valve 5 from other cavities in the hydraulic circuit;

[0053] The second one-way valve 9 is used to one-way isolate the chamber connected to the boosting chamber of the boosting cylinder 2 from other chambers in the hydraulic circuit;

[0054] The third pressure sensor 10 is used to detect the pressure of the left working chamber of the booster cylinder 2 p B ;

[0055] The actuator cylinder 11 is used to drive the motion mechanism of the hydraulic press. The piston displacement of the actuator cylinder 11 is s a The effective area is A a .

[0056] Among them: the boosting chamber of the boosting cylinder 2 is connected with the oil port of the first pressure sensor 1, the oil outlet of the second one-way valve 9, and the working chamber of the actuator cylinder 11. The volume of the connected chamber is V ; The piston of the boost cylinder 2 and the detection end of the displacement sensor 3 belong to the same assembly; the right action chamber of the boost cylinder 2 is connected to the oil port of the second pressure sensor 4 and the A port of the servo valve 5; the left action chamber of the boost cylinder 2 is connected to the oil port of the third pressure sensor 10 and the B port of the servo valve 5; the P port of the servo valve 5 is connected to the oil outlet of the first check valve 8; the T port of the servo valve 5 is connected to the hydraulic oil tank; the oil port of the constant pressure oil source 7 is connected to the oil inlet of the first check valve 8 and the second check valve 9; the controller 6 is electrically connected to the first pressure sensor 1, the displacement sensor 3, the second pressure sensor 4, the servo valve 5 and the third pressure sensor 10.

[0057] In practical applications, the displacement sensor 3 adopts a high-precision, high-response linear sensor such as a grating scale or a magnetic scale. The sensor output signal is a digital quantity, and the displacement signal is easy to realize dynamic digital differential calculation; the controller 6 generally adopts a digital controller such as a PLC; the constant pressure oil source 7 is realized by a constant pressure variable pump or a quantitative pump plus an overflow valve.

[0058] See also Figure 2 The control method of the present invention at least comprises the following steps:

[0059] Step 1: Plan the pressure expectations of the working chamber of the actuator cylinder 11 and the booster chamber of the booster cylinder 2 to be p d ; Set the displacement error threshold e t As a control switching point, e t It is a positive number and is related to the efficiency of boost cylinder 2.

[0060] Step 2: According to p d Calculate the ideal displacement of the piston in booster cylinder 2 s d , the calculation formula is:

[0061] ;

[0062] Where: E is the bulk modulus of hydraulic oil. V=V 0 −A c ×s+A a ×s a , V 0 yes V The initial value of .

[0063] Step 3: Controller 6 compares the displacement error ( s d −s ) and the absolute value of e t The size of when | s d −s |> e t When , the control command signal expression of servo valve 5 is:

[0064] u v =u vs =f s ( sd −s );

[0065] u vs It is an auxiliary control instruction based on the displacement state of the piston of booster cylinder 2.

[0066] f s ( s d −s ) is any value that can make the displacement error ( s d −s ) is a control function whose absolute value approaches 0. f s ( s d −s ) is a dynamic fast response control, which contains the displacement variable s d , s Differential calculation, in practical applications f s ( s d −s ) PID and other control algorithms can be used.

[0067] Step 4: When | s d −s |≤ e t When , the controller 6 calculates the following two values:

[0068] u vp =f p ( p d −p C );

[0069] u vst =f s ( e t );

[0070] u vp It is a direct control instruction based on the pressure state of the boost chamber of boost cylinder 2.

[0071] Controller 6 Comparison u vp and u vstThe absolute value of the servo valve 5 is taken as the control command signal of the servo valve 5. u v The minimum absolute value algorithm is used to ensure that the control command signal is always convergent during the switching process, avoiding the impact and vibration of the switching process.

[0072] f p ( p d −p C ) is any value that can make the pressure error ( p d −p C ) is a control function whose absolute value approaches 0. f p ( p d −p C ) is a static precise control, without the need to adjust the pressure variable p d , p C Differential calculations are performed to avoid the computational difficulties caused by signal interference. f p ( p d −p C ) Control algorithms such as PI can be used.

[0073] With the help of s Can be carried out p C Dynamic estimation calculation, the calculation formula is:

[0074] ;

[0075] Where: E is the bulk modulus of hydraulic oil. V=V 0 −A c ×s+A a ×s a , V 0 yes V The initial value of .

[0076] The controller 6 uses the command signal u v Control servo valve 5.

[0077] e tIt is inversely proportional to the efficiency of boost cylinder 2. The higher the efficiency of boost cylinder 2, the e t The smaller the value, the more debugging and adjustment are needed in actual application. e t In order to obtain a stable control effect.

Claims

1. A control method for an ultra-high pressure boosting system of a hydraulic press, characterized by: The hardware system includes: A first pressure sensor (1) is used to detect the pressure of the boost chamber of the boost cylinder (2); p C ; The booster cylinder (2) is used to increase the pressure of the working chamber of the actuator cylinder (11) to a level above the rated pressure of the constant pressure oil source (7). The working area of ​​the booster chamber of the booster cylinder (2) is A C ; A displacement sensor (3) for detecting the displacement of the piston of the boost cylinder (2) s ; The second pressure sensor (4) is used to detect the pressure of the right working chamber of the booster cylinder (2). p A ; The servo valve (5) is used to control the movement of the piston of the booster cylinder (2). The control command signal of the servo valve (5) is: u v ; A controller (6) for collecting signals from the first pressure sensor (1), the displacement sensor (3), the second pressure sensor (4), and the third pressure sensor (10), performing control calculations, and transmitting control command signals to the servo valve (5); A constant pressure oil source (7), used for providing hydraulic oil medium and maintaining a constant rated pressure of the system; A first one-way valve (8) is used to one-way isolate the chamber connected to the P port of the servo valve (5) from other chambers in the hydraulic circuit; A second one-way valve (9) is used to one-way isolate the chamber connected to the boosting chamber of the boosting cylinder (2) from other chambers in the hydraulic circuit; The third pressure sensor (10) is used to detect the pressure of the left working chamber of the boost cylinder (2). p B ; The actuator cylinder (11) is used to drive the motion mechanism of the hydraulic press. The piston displacement of the actuator cylinder (11) is s a The effective area is A a ; The boosting chamber of the boosting cylinder (2) is connected to the oil port of the first pressure sensor (1), the oil outlet of the second one-way valve (9), and the action chamber of the actuator cylinder (11), and the volume of the connected chamber is V The piston of the booster cylinder (2) and the detection end of the displacement sensor (3) belong to the same assembly; the right action chamber of the booster cylinder (2) is connected to the oil port of the second pressure sensor (4) and the A port of the servo valve (5); the left action chamber of the booster cylinder (2) is connected to the oil port of the third pressure sensor (10) and the B port of the servo valve (5); the P port of the servo valve (5) is connected to the oil outlet of the first check valve (8); the T port of the servo valve (5) is connected to the hydraulic oil tank; the oil port of the constant pressure oil source (7) is connected to the oil inlet of the first check valve (8) and the second check valve (9); the controller (6) is electrically connected to the first pressure sensor (1), the displacement sensor (3), the second pressure sensor (4), the servo valve (5) and the third pressure sensor (10); The control method of the ultra-high pressure boosting system of a hydraulic press comprises the following steps: Step 1: Plan the pressure expectations of the working chamber of the actuator cylinder (11) and the booster chamber of the booster cylinder (2) as follows: p d ; Set the displacement error threshold e t As a control switching point, e t is a positive number and is related to the efficiency of the boost cylinder (2); Step 2: According to p d Calculate the ideal desired displacement of the piston in the booster cylinder (2) s d , the calculation formula is: ； Where: E is the bulk modulus of the hydraulic oil; V=V 0 −A c ×s+A a ×s a , V 0 yes V The initial value of Step 3: The controller (6) compares the displacement error ( s d −s ) and the absolute value of e t The size of when | s d −s |> e t When , the control command signal expression of the servo valve (5) is: u v =u vs =f s ( s d −s )； u vs is an auxiliary control instruction based on the displacement state of the piston of the boost cylinder (2); f s ( s d −s ) is able to make the displacement error ( s d −s ) is a control function whose absolute value approaches 0. f s ( s d −s ) is a dynamic fast response control, which contains the displacement variable s d , s Differential calculation of ; Step 4: When | s d −s |≤ e t When , the controller (6) calculates the following two values: u vp =f p ( p d −p C )； u vst =f s ( e t )； u vp is a direct control instruction based on the pressure state of the boost chamber of the boost cylinder (2); Controller (6) Comparison u vp and u vst The absolute value of the servo valve (5) is used as the control command signal of the servo valve (5). u v ; f p ( p d −p C ) is able to make the pressure error ( p d −p C ) is a control function whose absolute value approaches 0. f p ( p d −p C ) is a static precise control, without the need to adjust the pressure variable p d , p C Perform differential calculations to avoid computational difficulties caused by signal interference; With the help of s conduct p C Dynamic estimation calculation, the calculation formula is: ； Where: E is the bulk modulus of the hydraulic oil; V=V 0 −A c ×s+A a ×s a , V 0 yes V The initial value of The controller (6) uses a command signal u v Control servo valve (5).

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