CN108561346B

CN108561346B - Precise pressure control system of servo pump control hydraulic machine and hydraulic machining method

Info

Publication number: CN108561346B
Application number: CN201810453721.6A
Authority: CN
Inventors: 请求不公布姓名
Original assignee: Jiangsu Yangli Hydraulic Equipment Co ltd
Current assignee: Jiangsu Yangli Hydraulic Equipment Co ltd
Priority date: 2018-05-14
Filing date: 2018-05-14
Publication date: 2023-08-25
Anticipated expiration: 2038-05-14
Also published as: CN108561346A

Abstract

The invention relates to a precise pressure control system of a servo pump control hydraulic machine and a hydraulic machining method, wherein the hydraulic machine comprises a medium-flow servo pump and a large-flow servo pump driven by a servo motor, an outlet pipeline of the two pumps is connected with an upper cavity oil way of a main cylinder through a dynamic valve seven, and the upper cavity oil way of the main cylinder is also connected with an oil tank through a dynamic valve four and a proportional valve; the main cylinder lower cavity pipeline is connected with the outlet of the cartridge valve nine, the inlet of the cartridge valve nine is connected with the oil tank through the cartridge valve five and the cartridge valve eight respectively, the cartridge valve five provides supporting force during deceleration pressurization through the overflow valve, and the cartridge valve eight is opened during return stroke. Each working cycle of the hydraulic machining comprises the following actions in sequence: automatic pressure compensation of the energy accumulator, stop pressure compensation of the energy accumulator, rapid descending of the sliding block, deceleration and pressurization of the sliding block, pressure maintaining of the sliding block, pressure relief of the sliding block, return stroke of the sliding block and shutdown. The servo driver adopts the switching of two modes of flow control and PID regulation control, realizes the stable pressurization of the sliding block, avoids the pressurization overshoot to deform the part, and releases pressure steadily.

Description

Precise pressure control system of servo pump control hydraulic machine and hydraulic machining method

Technical Field

The invention relates to a hydraulic machine, in particular to a precise pressure control system of a servo pump control hydraulic machine, and also relates to a hydraulic machining method of the hydraulic machine, belonging to the technical field of machine tool control systems.

Background

The normal process mode of the hydraulic machine has two control modes of fixed stroke and fixed pressure, the fixed stroke state is controlled by the stop position of the sliding block, the fixed pressure state is controlled by the pressure value generated after the sliding block drives the upper die and the lower die to be completely closed, but the quick down operation of the sliding block in the fixed pressure state is controlled by a position signal, so the fixed pressure mode is controlled by initially using position feedback, and the fixed pressure mode is converted into pressure control after the actuating mechanism is contacted with a load, and the controller is required to have the mathematical operation capability of stably converting a position PID algorithm into a force PID control algorithm.

The current mode of realizing accurate pressure control in the market is usually that a three-phase asynchronous motor drives a constant-power variable pump and then realizes pressure control through an overflow valve or a pressure regulator, some manufacturers adopt a proportional overflow valve to replace a manual pressure regulating valve to realize control, the pressure control is realized through the quick response of the proportional valve, and even some devices realize accurate pressure control by utilizing the high response and high precision of a servo valve. The three-phase asynchronous motor is adopted to drive the constant-power variable pump and is matched with the manual or proportional overflow valve, so that the phenomenon of stabilization after pressure overshoot is easy to occur, and irrecoverable deformation can be generated for some parts, thus forming defective products.

In recent years, a gear pump driven by a servo motor is also adopted in the market, and the high response and control flexibility of the servo are utilized to realize the accurate control of the pressure. The cartridge valve structure is commonly adopted in the application of the hydraulic system, and the pressure maintaining state is commonly adopted in an overflow mode, which is also a main cause for the increase of the oil temperature. The response (such as reversing, opening and the like) of the cartridge valve system is not timely, and overpressure and pressure oscillation are easy to generate; the control signal is easy to be disturbed by adopting analog quantity, and particularly, the remote control or the multi-pump confluence control is obvious. When the servo pump is used for control, the pressure sensor at the pump port and the pressure sensor at the upper cavity of the main cylinder are both arranged, and the sensor is not only easy to be interfered, but also inconvenient to troubleshoot due to the adoption of voltage signals. Under high-frequency operation, impact noise is large during pressure relief, and fixing pieces are easy to loosen.

Disclosure of Invention

The invention aims at overcoming the problems existing in the prior art and providing a precise pressure control system of a servo pump control hydraulic machine, which can realize stable pressurization of a sliding block, avoid overshoot and has high precision of pressure control.

In order to solve the technical problems, the precise pressure control system of the servo pump controlled hydraulic press comprises a main cylinder 1 arranged above a sliding block, wherein the lower cavity of the main cylinder 1 is connected with a main cylinder lower cavity oil way G1, the upper cavity of the main cylinder 1 is connected with a main cylinder upper cavity oil way G2, the precise pressure control system also comprises a medium-flow servo pump B1 and a large-flow servo pump B2 which are driven by a servo motor M1 together, the outlet of the medium-flow servo pump B1 is connected with the inlet of a cartridge valve CZ1, the outlet of the large-flow servo pump B2 is connected with the inlet of a cartridge valve CZ2, the hydraulic control ports of the cartridge valve CZ1 and the cartridge valve CZ2 are respectively connected with the respective outlets, the outlets of the cartridge valve CZ1 and the cartridge valve CZ2 are connected with a main pump outlet pipeline G3, the outlet of a dynamic valve C7 is connected with the inlet of the main cylinder upper cavity oil way G2, the hydraulic control port A of the dynamic valve C7 is connected with the inlet of a seven-way valve Y7 through a throttle valve, the hydraulic control port A of the dynamic valve CZ 7 is connected with the electromagnetic valve YV7 through a seven-way valve YV7, and the hydraulic control port B of the electromagnetic valve YV7 is connected with the electromagnetic valve YV7 through a seven-way valve YV7, and the electromagnetic valve Y is connected with the electromagnetic valve YV7 is connected with the electromagnetic valve Y7.

Compared with the prior art, the invention has the following beneficial effects: when the sliding block rapidly descends, the servo motor I M1 drives pressure oil pumped by the large-flow servo pump B2 to enter the main pump outlet pipeline G3 through the cartridge valve II CZ2, and pressure oil pumped by the medium-flow servo pump B1 enters the main pump outlet pipeline G3 through the cartridge valve I CZ 1; when the sliding block is in deceleration and pressurization or pressure maintaining, only the pressure oil pumped by the medium-flow servo pump B1 enters the main pump outlet pipeline G3 through the cartridge valve CZ 1; when the electromagnetic reversing valve seven YV7 is electrified, the P port and the A port are directly communicated, the B port and the T port are directly communicated, the dynamic valve seven C7 is rapidly opened, and pressure oil in the main pump outlet pipeline G3 enters the main cylinder upper cavity oil way G2. The invention removes the one-way valve in the main cylinder oil supply channel in the traditional hydraulic system, directly controls the pressure of the main cylinder upper cavity by the servo pump, and eliminates the pressure difference between the main pump outlet pipeline G3 and the main cylinder upper cavity oil way G2. The dynamic valve which is quick in opening and closing time and can ensure the valve core to be reliably seated is adopted, and the high flexibility of the servo pump is matched to realize the timely response of unidirectional control, so that the pressure oscillation is avoided.

The invention is improved by the invention, the invention also comprises a small-flow servo pump B3 driven by a servo motor II M2, the outlet of the small-flow servo pump B3 is connected with the inlet of a cartridge valve III CZ3, the hydraulic control port of the cartridge valve III CZ3 is connected with the A port of an electromagnetic directional valve III YV3, the P port of the electromagnetic directional valve III YV3 is connected with an auxiliary oil supply pipe G5, the T port of the electromagnetic directional valve III YV3 is connected with a lower oil tank, the electromagnetic directional valve III YV3 is a D-type two-position four-way electromagnetic directional valve, the outlet of the cartridge valve III CZ3 is connected with the auxiliary oil supply pipe G5, and the outlet of the auxiliary oil supply pipe G5 is connected with a control oil pipe G4 through a ball valve I V1; the auxiliary oil supply pipe G5 is connected with an accumulator AC and an accumulator pressure sensor PN2. Before working, 6MPa of nitrogen is filled into the accumulator AC, and the ball valve V1 is opened; before the sliding block acts, a servo motor II M2 is started, a small-flow servo pump B3 pumps out pressure oil, at the moment, an electromagnetic directional valve III YV3 is powered on, an A port is communicated with a T port, a P port is communicated with a B port, a cartridge valve III CZ3 is opened, an auxiliary oil supply pipe G5 builds pressure and supplements pressure for an accumulator AC, when an accumulator pressure sensor PN2 detects that the pressure of the accumulator AC is 16Mpa, the electromagnetic directional valve III YV3 is powered off to enable the cartridge valve III CZ3 to be closed, and meanwhile, the small-flow servo pump B3 stops supplementing pressure for the accumulator AC, and the auxiliary oil supply pipe G5 and the accumulator AC provide pressure oil for a control oil pipe G4. Because the oil consumption of the control oil is smaller, the invention adopts the small-flow servo pump B3 to supplement the pressure to the accumulator AC, and then utilizes the energy storage function of the accumulator AC to provide the control oil for the system, thereby reducing the starting of the large pump and saving energy.

As a further improvement of the invention, a pump port pressure sensor PN1 is arranged at the outlet of the medium-flow servo pump B1 and is connected with the inlet of a dynamic valve I C1, the outlet of the dynamic valve I C1 is connected with a lower oil tank, a hydraulic control port A of the dynamic valve I C1 is connected with an A port of an electromagnetic directional valve I YV1 through a throttle valve, a hydraulic control port B of the dynamic valve I C1 is connected with a B port of the electromagnetic directional valve I YV1 through a throttle valve, a P port of the electromagnetic directional valve I YV1 is connected with a control oil liquid pipe G4, and a T port of the electromagnetic directional valve I YV1 is connected with the lower oil tank; the outlet pipeline of the large-flow servo pump B2 is connected with the inlet of a dynamic valve II C2, the outlet of the dynamic valve II C2 is connected with a lower oil tank, the hydraulic control port A of the dynamic valve II C2 is connected with the port A of an electromagnetic directional valve II YV2 through a throttle valve, the hydraulic control port B of the dynamic valve II C2 is connected with the port B of the electromagnetic directional valve II YV2 through a throttle valve, the port P of the electromagnetic directional valve II YV2 is connected with a control oil pipe G4, and the port T of the electromagnetic directional valve II YV2 is connected with the lower oil tank; the electromagnetic directional valve one YV1 and the electromagnetic directional valve two YV2 are D-type two-position four-way electromagnetic directional valves. When the sliding block moves down or returns quickly, the electromagnetic reversing valve YV1 is electrified, the port P is communicated with the port B, the port A is communicated with the port T, and the dynamic valve C1 is closed quickly; meanwhile, the electromagnetic reversing valve II YV2 is electrified, the port P is communicated with the port B, the port A is communicated with the port T, the dynamic valve II C2 is rapidly closed, and the medium-flow servo pump B1 and the large-flow servo pump B2 work simultaneously, so that the pressure of the main pump outlet pipeline G3 is rapidly built. When the sliding block is in deceleration and pressurization or pressure maintaining, the electromagnetic directional valve II YV2 is powered off to enable the dynamic valve II C2 to be opened rapidly, the large-flow servo pump B2 stops working, the electromagnetic directional valve I YV1 is kept in a power-on state, and oil is supplied to the main pump outlet pipeline G3 independently by the medium-flow servo pump B1. When the sliding block is depressurized, the first electromagnetic reversing valve YV1 and the second electromagnetic reversing valve YV2 are powered off simultaneously, and the medium-flow servo pump B1 and the large-flow servo pump B2 do not work. The pump port pressure sensor PN1 feeds back the pressure of the outlet of the middle flow servo pump B1 to the control system in real time, the high response of the servo motor M1 is combined, the flow output of the middle flow servo pump B1 is adjusted, when the pressure of the main pump outlet pipeline G3 is not established, the oil pressure is established by flow control, when the pressure of the main pump outlet pipeline G3 is established, the oil pressure of the main pump outlet pipeline G3 is regulated and controlled by PID, stable pressurization can be realized, overshoot is avoided, the accuracy of pressure control is ensured, and the deformation which can not restore parts is avoided.

As a further improvement of the invention, the outlet pipeline of the medium-flow servo pump B1 is connected with the lower oil tank through a first pressure regulating valve F1, the outlet pipeline of the large-flow servo pump B2 is connected with the lower oil tank through a second pressure regulating valve F2, and the auxiliary oil supply pipe G5 is also connected with the lower oil tank through a third pressure regulating valve F3 and a second ball valve V2 respectively. When the outlet pressure of the middle flow servo pump B1 reaches 25MPa, the first pressure regulating valve F1 is opened to relieve pressure so as to protect the middle flow servo pump B1. When the outlet pressure of the large-flow servo pump B2 reaches 10MPa, the second pressure regulating valve F2 is opened to relieve pressure so as to protect the large-flow servo pump B2. When the pressure of the auxiliary oil supply pipe G5 reaches 16MPa, the pressure regulating valve three F3 is opened for pressure relief so as to protect the safety of the system.

As a further improvement of the invention, the outlet of the main pump outlet pipeline G3 is connected with the inlet of the cartridge valve eight CZ8, the outlet of the cartridge valve eight CZ8 is connected with the inlet of the cartridge valve nine CZ9, and the outlet of the cartridge valve nine CZ9 is connected with the main cylinder lower cavity oil way G1; the hydraulic control port of the cartridge valve eight CZ8 is connected with the middle outlet of the shuttle valve S1, the right inlet of the shuttle valve S1 is connected with the outlet of the cartridge valve eight CZ8, the left inlet of the shuttle valve S1 is connected with the A port of the electromagnetic directional valve eight YV8, the P port of the electromagnetic directional valve eight YV8 is connected with the inlet of the cartridge valve eight CZ8, the T port of the electromagnetic directional valve eight YV8 is connected with the lower oil tank, and the electromagnetic directional valve eight YV8 is a D-type two-position four-way electromagnetic directional valve; the hydraulic control port of the cartridge valve nine CZ9 is connected with the A port of the electromagnetic directional valve nine YV9, the P port of the electromagnetic directional valve nine YV9 is connected with the outlet of the cartridge valve nine CZ9, the T port of the electromagnetic directional valve nine YV9 is connected with the lower oil tank, and the electromagnetic directional valve nine YV9 is a two-position three-way electromagnetic directional valve; the main cylinder lower cavity oil way G1 is also connected with a lower oil tank through a pressure regulating valve F4. When the sliding block rapidly descends, is pressurized in a decelerating way or is pressurized in a pressure maintaining way, the electromagnetic directional valve nine YV9 is powered on, the port A is communicated with the port T, the cartridge valve nine CZ9 is opened, the oil in the oil way G1 of the lower cavity of the main cylinder is discharged or the supporting pressure is kept, at the moment, the electromagnetic directional valve eight YV8 is in a power-losing state, the port P is directly communicated with the port A, the port B is directly communicated with the port T, the shuttle valve S1 ensures that the hydraulic control port of the cartridge valve eight CZ8 is pressurized, and the cartridge valve eight CZ8 is in a reliable closing state. When the sliding block is depressurized, the electromagnetic reversing valve nine YV9 is powered off, and the cartridge valve nine CZ9 is closed. When the sliding block returns, the electromagnetic directional valve eight YV8 is powered on, the port A is communicated with the port T, the hydraulic control port pressure of the cartridge valve eight CZ8 is lower than the inlet pressure, the cartridge valve eight CZ8 is opened, meanwhile, the electromagnetic directional valve nine YV9 is powered on simultaneously, the cartridge valve nine CZ9 is opened, pressure oil in the main pump outlet pipeline G3 enters the main cylinder lower cavity oil way G1, and the sliding block is driven to move upwards by retracting the piston of the main cylinder 1.

As a further improvement of the invention, the inlet of the cartridge valve nine CZ9 is connected with the inlet of the cartridge valve five CZ5, the outlet of the cartridge valve five CZ5 is connected with the lower oil tank, the hydraulic control port of the cartridge valve five CZ5 is connected with the A ports of the electromagnetic directional valves five YV5 and YV6, the B port and the T port of the electromagnetic directional valve five are respectively connected with the lower oil tank, the P port of the electromagnetic directional valve five is connected with the lower oil tank through the pressure regulating valve five F5, the A port of the electromagnetic directional valve five is connected with the lower oil tank through the pressure regulating valve six F6, and the electromagnetic directional valve five is a three-position four-way electromagnetic directional valve with the median function of O. When the sliding block rapidly descends, the left coil YV6 of the electromagnetic directional valve five is electrified to be at a left station, the hydraulic control port of the cartridge valve five CZ5 is communicated with the oil tank, the cartridge valve five CZ5 is opened, the oil way G1 of the main cylinder lower cavity is directly communicated with the oil tank, and no supporting force of the lower cavity of the main cylinder 1 is realized. When the sliding block is in deceleration and pressurization or pressure maintaining, the right coil YV5 of the electromagnetic reversing valve five is electrified to be at a right station, the hydraulic control port of the cartridge valve five CZ5 is controlled by the pressure regulating valve five F5, and the back pressure of the lower cavity of the main cylinder 1 is controlled to be 5 MPa-8 MPa by the pressure regulating valve five F5. When the sliding block is released or returns, the electromagnetic reversing valve five loses electricity and is in the middle position, the hydraulic control port of the cartridge valve five CZ5 is controlled by the pressure regulating valve six F6, and when the upper limit pressure reaches 25MPa, the pressure regulating valve six F6 is opened.

As a further improvement of the invention, an oil way G2 of an upper cavity of a master cylinder is connected with an inlet of a dynamic valve C4, an outlet of the dynamic valve C4 is connected with an upper oil tank, a hydraulic control port A of the dynamic valve C4 is connected with an A port of an electromagnetic reversing valve Y4 through a throttle valve, a hydraulic control port B of the dynamic valve C4 is connected with a B port of the electromagnetic reversing valve Y4 through a throttle valve, a P port of the electromagnetic reversing valve Y4 is connected with a control oil pipe G4, a T port of the electromagnetic reversing valve Y4 is connected with an upper oil tank, and the electromagnetic reversing valve Y4 is a D-type two-position four-way electromagnetic reversing valve; the master cylinder upper chamber oil passage G2 is also connected to an inlet of a proportional valve YAA, and an outlet of the proportional valve YAA is connected to the tank. When the sliding block rapidly descends or returns, the proportional valve YAA is powered off, the electromagnetic reversing valve four YV4 is powered off, the port P is directly connected with the port A, the port B is directly connected with the port T, the dynamic valve four C4 is rapidly opened, and the upper cavity of the main cylinder 1 is communicated with the upper oil tank; when the sliding block is quickly lowered, the upper oil tank can quickly supplement oil to the upper cavity of the main cylinder; when the sliding block returns, the oil in the upper cavity of the main cylinder can quickly return to the upper oil tank. When the sliding block is in deceleration and pressurization or pressure maintaining, the proportional valve YAA is powered off and closed, the electromagnetic reversing valve four YV4 is powered on to enable the dynamic valve four C4 to be closed rapidly, and the upper cavity pressure of the main cylinder 1 is directly controlled by the medium flow servo pump B1. When the pressure maintaining of the sliding block is finished, the proportional valve YAA is powered on firstly to pre-discharge to a certain pressure, then the electromagnetic reversing valve four YV4 is powered off to enable the dynamic valve four C4 to be opened rapidly, the upper cavity of the main cylinder 1 is communicated with the upper oil tank to realize the pressure relief of the sliding block, the proportional valve YAA is controlled by an electric signal in the process to realize the rapid pressure relief and the opening can be controlled to be opened linearly, and therefore the smooth transition from the pressure maintaining of the sliding block to the pressure relief is realized without impact.

As a further improvement of the invention, a servo motor M1 is controlled by a servo driver SDR, a three-phase alternating current power supply is connected with a power end of the servo driver SDR through a breaker QF1 and a filter EM1, an encoder PG arranged at the tail part of the servo motor M1 is connected to a CN1 port of the servo driver SDR, a pump port pressure sensor PN1 is a current feedback pressure sensor and is connected to a CN2 port of the servo driver SDR, an A01 pin of a CN3 port of the servo driver SDR is connected with an AIO+ port of an SM231 module of a PLC controller, and an AGND pin of a CN3 port of the servo driver SDR is connected with an AIO-port of an SM231 module of the PLC controller; the CAN communication interface of the servo driver SDR is connected with the CANopen module of the PLC; the servo enabling button SB1 is connected between the starting signal input end S-ON and the V1+ port of the servo driver SDR, and the alarm reset button SB2 is connected between the reset signal input end ALM-RST and the V1+ port of the servo driver SDR; the coil of the relay KA1 is connected between an alarm signal end ALM and a V1-port of the servo driver SDR, and a normally open contact of the relay KA1 is connected in series between a 0.0 port and a V1+ port of an SM223 module of the PLC controller; the coil of the relay two KA2 is connected between the double-pump converging signal input end TGON and the V1-port of the servo driver SDR, and the normally open contact of the relay two KA2 is connected in series between the 0.1 port and the V1+ port of the SM223 module of the PLC controller; the CPU of the PLC is connected with the touch screen PM1 through an Ethernet communication line, the port of V1 is connected with +24VDC, and the port of V1 is grounded; the servo driver SDR adopts a ProNet-2BDIB Esston servo driver, and the PLC controller adopts Siemens 6ES7215-1BG40-0XB0 type. The servo driver SDR acquires a digital signal sent by the encoder PG and precisely controls the operation of a servo motor M1; after receiving a pump port pressure signal sent by a pump port pressure sensor PN1, a servo driver SDR converts the pump port pressure signal into an analog signal controlled by 0-10v pressure and sends the analog signal to an SM223 module of a PLC (programmable logic controller) through a CN3 port, and after comparing the pressure signal, the PLC sends a control signal to a CAN communication interface of the servo driver SDR through a CANopen module, and the servo driver SDR selectively adopts flow control or PID to adjust and control oil pressure; the method changes the traditional adopted flow and pressure control to set 0-10V analog signals as digital bus control, adopts a CANOpen protocol to communicate in an industrial environment with stronger interference through a CAN communication interface, and solves the problem that the remote transmission of the analog signals is easy to be interfered; the servo controller can be arranged close to the servo motor, the motor cable is shortened, and meanwhile, servo operation information and alarm content can be displayed in a picture of the touch screen after being transmitted through a bus. When the slide block rapidly descends, the main pump outlet pipeline G3 is not pressurized, the servo driver SDR controls the operation of the servo motor M1 by using the flow, and the large-flow servo pump B2 and the medium-flow servo pump B1 supply oil together. When the slide block is used for decelerating and pressurizing or maintaining pressure, the main pump outlet pipeline G3 is already pressurized and is independently supplied with oil by the middle flow servo pump B1, the pump port pressure sensor PN1 feeds back the pressure of the outlet of the middle flow servo pump B1 to the servo driver SDR in real time, the high response of the servo motor M1 is combined, the flow output of the middle flow servo pump B1 is regulated, the servo driver SDR adopts PID to regulate and control the oil pressure of the main pump outlet pipeline G3, stable pressurization can be realized, overshoot is avoided, the accuracy of pressure control is ensured, and deformation which can not restore parts is avoided. The pump port pressure sensor PN1 adopts a current feedback pressure sensor, so that the electric noise interference can be solved, and the diagnosis when the line is broken or the power supply is not connected is facilitated. After a servo enabling button SB1 is pressed, a servo driver SDR is started, when the pressure of a main pump outlet pipeline G3 is lower than 10MPa, a coil of a relay two KA2 is powered on, a normally open contact of the relay two KA2 is closed, a PLC receives a double-pump confluence signal, an electromagnetic reversing valve two YV2 is powered on, a dynamic valve two C2 is rapidly closed, and a large-flow servo pump B2 and a medium-flow servo pump B1 supply oil simultaneously. When the servo driver SDR detects faults such as overcurrent, a coil of the relay KA1 is electrified, a normally open contact of the relay KA1 is closed, the PLC receives an alarm signal, the PLC prompts the alarm signal on the touch screen PM1 through an Ethernet communication wire, and an alarm reset button SB2 is pressed down to reset the alarm.

Another object of the present invention is to overcome the problems of the prior art, and to provide a method for hydraulic processing by using a hydraulic system of a hydraulic machine, which has low energy consumption, can realize stable pressurization of a slide block, avoids overshoot, and has no impact due to pressure relief.

In order to solve the technical problems, the invention adopts a hydraulic processing method of a hydraulic system of a hydraulic machine, and each working cycle sequentially comprises the following actions: automatic pressure supplementing of an energy accumulator: firstly, 6MPa of nitrogen is filled into an accumulator AC, a second servo motor M2 is started and an electromagnetic reversing valve three YV3 is electrified before a sliding block acts, and a small-flow servo pump B3 pumps out pressure oil to supplement the pressure of the accumulator AC; the pressure supplementing of the energy accumulator is stopped: when the charging pressure of the accumulator AC reaches 16Mpa, the electromagnetic reversing valve three YV3 is powered off to close the cartridge valve three CZ3, and the small-flow servo pump B3 is stopped; the sliding block rapidly descends: the electromagnetic directional valve nine YV9 is powered on to enable the cartridge valve nine CZ9 to be opened, the electromagnetic directional valve five is switched to the left station to enable the cartridge valve five CZ5 to be opened, and oil in the lower cavity of the main cylinder is directly communicated with the oil return tank; the electromagnetic directional valve one YV1 and the electromagnetic directional valve two YV2 are powered on simultaneously, the large-flow servo pump B2 and the medium-flow servo pump B1 supply oil together, the electromagnetic directional valve seven YV7 is powered on to enable the dynamic valve seven C7 to be opened rapidly, oil enters the upper cavity of the main cylinder, meanwhile, the electromagnetic directional valve four YV4 is powered off to enable the dynamic valve four C4 to be opened rapidly, and oil in the upper oil tank is fed into the upper cavity of the main cylinder rapidly along with the rapid descending of the sliding block; fourth, the slide block is decelerated and pressurized: the second electromagnetic reversing valve YV2 is powered off to enable the second dynamic valve C2 to be opened rapidly, the first electromagnetic reversing valve YV1 is kept powered on, and the medium-flow servo pump B1 is used for independently supplying oil; the electromagnetic reversing valve four YV4 is electrified to enable the dynamic valve four C4 to be rapidly closed, the pressure of the upper cavity of the main cylinder is directly controlled by the medium-flow servo pump B1, the electromagnetic reversing valve five is switched to the right station, and the pressure of the lower cavity of the main cylinder is controlled by the pressure regulating valve five F5; maintaining pressure of the sliding block: the state of each valve is kept for a period of time, and the flow servo pump B1 controls the pressure of the pressure maintaining; sixth step of sliding block pressure relief: the proportional valve YAA is powered on firstly, and the pressure of the upper cavity of the main cylinder is pre-relieved; then the electromagnetic directional valve one YV1, the electromagnetic directional valve four YV4, the electromagnetic directional valve five, the electromagnetic directional valve seven YV7 and the electromagnetic directional valve nine YV9 are all powered off, and the sliding block can completely release pressure; slide return: the electromagnetic directional valve one YV1 and the electromagnetic directional valve two YV2 are powered simultaneously, the large-flow servo pump B2 and the medium-flow servo pump B1 supply oil together, the electromagnetic directional valve eight YV8 is powered to open the cartridge valve eight CZ8, the electromagnetic directional valve nine YV9 is powered to open the cartridge valve nine CZ9, pressure oil enters the lower cavity of the main cylinder, and the main cylinder drives the sliding block to move upwards; the proportional valve YAA is powered off and closed, the electromagnetic directional valve seven YV7 is powered off to keep the dynamic valve seven C7 closed, the electromagnetic directional valve four YV4 is powered off to keep the dynamic valve four C4 open, and oil in the upper cavity of the master cylinder can quickly return to the upper oil tank; stopping: all the electromagnetic directional valves are powered off, and the servo motor is stopped.

Compared with the prior art, the invention has the following beneficial effects: the small-flow servo pump B3 is adopted to carry out liquid filling and pressure supplementing on the energy accumulator AC, so as to provide control oil for the system, reduce the starting of the large-flow servo pump and save energy; the large-flow servo pump B2 is only used for supplying oil when the sliding block is fast down or returns, so that the energy consumption can be further reduced, and the equipment failure rate is reduced. The one-way valve in the main cylinder oil supply channel in the traditional hydraulic system is removed, the servo pump directly controls the pressure of the main cylinder upper cavity, and the pressure difference between the main pump outlet pipeline G3 and the main cylinder upper cavity oil way G2 is eliminated, so that the control precision is higher; the pressure maintaining pressure is controlled by the flow servo pump B1, overflow is not needed, and the oil temperature is reduced; the dynamic valve which is quick in opening and closing time and can ensure the valve core to be reliably seated is adopted, and the high flexibility of the servo pump is matched to realize the timely response of unidirectional control, so that the pressure oscillation is avoided. And when the pressure maintaining is finished, the pressure is released in advance through the proportional valve YAA, so that the impact-free pressure release is realized, and the smooth transition from the pressure maintaining of the sliding block to the pressure release is realized. The pump port adopts a current feedback pressure sensor, so that the interference of electric noise can be solved, and diagnosis when a wire is disconnected or a power supply is not connected can be conveniently carried out. The CANOpen protocol is adopted to communicate in an industrial environment with stronger interference through a CAN communication interface, so that the problem that the remote transmission of analog signals is easy to be interfered is solved; the servo controller can be arranged close to the servo motor, and the motor cable is shortened.

As an improvement of the invention, when the slide block rapidly descends, the main pump outlet pipeline G3 is not pressurized, and the servo driver SDR controls the operation of a servo motor M1 by using the flow; when the slide block is used for decelerating and pressurizing or maintaining pressure, the main pump outlet pipeline G3 is already pressurized and is independently supplied with oil by the middle flow servo pump B1, the pump port pressure sensor PN1 feeds back the pressure of the outlet of the middle flow servo pump B1 to the servo driver SDR in real time, the high response of the servo motor M1 is combined, the flow output of the middle flow servo pump B1 is regulated, and the servo driver SDR adopts PID to regulate and control the oil pressure of the main pump outlet pipeline G3, so that stable pressurization is realized and overshoot is avoided; when the sliding block is depressurized, the proportional valve YAA is controlled through an electric signal, so that the rapid pressure relief can be realized, the opening can be controlled to be opened linearly, no impact is realized, and the smooth transition from the pressure maintaining to the pressure relief of the sliding block is realized. The servo driver SDR adopts two modes of flow control and PID regulation control to switch, so that stable pressurization of the sliding block can be realized, the accuracy of pressure control is ensured, and the deformation of the parts, which cannot be recovered due to pressurization overshoot, is avoided. And the pressure relief can not cause great impact noise and loosening of the fixing piece.

Drawings

The invention will now be described in further detail with reference to the drawings and the detailed description, which are provided for reference and illustration only and are not intended to limit the invention.

FIG. 1 is a hydraulic schematic diagram of a precision pressure control system of a servo pump controlled hydraulic machine of the present invention.

FIG. 2 is an electrical schematic diagram of a precision pressure control system for a servo-pump controlled hydraulic machine of the present invention.

In the figure: 1. a master cylinder; B1. a medium flow servo pump; B2. a large flow servo pump; B3. a small flow servo pump; m1, a servo motor I; m2, a servo motor II; ac, accumulator; PN1, a pump port pressure sensor; PN2, accumulator pressure sensor; G1. a master cylinder lower chamber oil path; G2. an oil path of the upper cavity of the main cylinder; G3. a main pump outlet line; G4. controlling an oil pipe; G5. an auxiliary oil supply pipe; yv1, electromagnetic directional valve one; yv2 electromagnetic directional valve two; yv3 electromagnetic directional valve three; yv4 electromagnetic directional valve four; YV5, YV6 electromagnetic directional valve five; yv7 electromagnetic reversing valve seven; yv8 electromagnetic reversing valve eight; yv9 electromagnetic reversing valve nine; yaa. Proportional valve; C1. a dynamic valve I; C2. a dynamic valve II; C4. a dynamic valve IV; C7. a dynamic valve seven; CZ1, cartridge valve I; CZ2, cartridge valve II; CZ3, cartridge valve III; cz5, cartridge valve five; CZ8 cartridge valve eight; CZ9 cartridge valve nine; s1, a shuttle valve; F1. a first pressure regulating valve; F2. a second pressure regulating valve; F3. a third pressure regulating valve; F4. a fourth pressure regulating valve; F5. fifthly, a pressure regulating valve; F6. a pressure regulating valve six; v1, a ball valve I; v2. ball valve two; SDR, servo driver; QF1, a breaker; EM1, a filter; pg, encoder; SB1, servo enabling button; SB2, alarm reset button; S-ON. start signal input terminal; ALM, alarm signal terminal; an ALM-rst reset signal input; tgon, double pump confluence signal input terminal; PM1, a touch screen; and R, braking resistance.

Detailed Description

As shown in fig. 1, the precise pressure control system of the servo pump controlled hydraulic press comprises a main cylinder 1 arranged above a sliding block, wherein the lower cavity of the main cylinder 1 is connected with a main cylinder lower cavity oil way G1, the upper cavity of the main cylinder 1 is connected with a main cylinder upper cavity oil way G2, the precise pressure control system also comprises a medium-flow servo pump B1 and a large-flow servo pump B2 which are driven by a servo motor M1 together, the outlet of the medium-flow servo pump B1 is connected with the inlet of a cartridge valve CZ1, the outlet of the large-flow servo pump B2 is connected with the inlet of a cartridge valve CZ2, the hydraulic control ports of the cartridge valve CZ1 and the cartridge valve CZ2 are respectively connected with the respective outlets, the outlets of the cartridge valve CZ1 and the cartridge valve CZ2 are connected with a main pump outlet pipeline G3, the outlet pipeline G3 of the main pump is connected with the inlet of a dynamic valve seven C7, the outlet of the dynamic valve seven C7 is connected with the inlet of the main cylinder upper cavity oil way G2, the hydraulic control port A of the dynamic valve seven C7 is connected with the inlet of a seven-way electromagnetic valve YV7 through a throttle valve, the hydraulic control port A of the dynamic valve seven C7 is connected with the seven-way valve YV7 through a throttle valve Y7, and the reversing valve YV7 is connected with the reversing valve YV7 through the reversing valve YT 7, and the reversing valve YT is connected with the reversing valve YT 7.

When the sliding block rapidly descends, the servo motor I M1 drives pressure oil pumped by the large-flow servo pump B2 to enter the main pump outlet pipeline G3 through the cartridge valve II CZ2, and pressure oil pumped by the medium-flow servo pump B1 enters the main pump outlet pipeline G3 through the cartridge valve I CZ 1; when the sliding block is in deceleration and pressurization or pressure maintaining, only the pressure oil pumped by the medium-flow servo pump B1 enters the main pump outlet pipeline G3 through the cartridge valve CZ 1; when the electromagnetic reversing valve seven YV7 is electrified, the P port and the A port are directly communicated, the B port and the T port are directly communicated, the dynamic valve seven C7 is rapidly opened, and pressure oil in the main pump outlet pipeline G3 enters the main cylinder upper cavity oil way G2. The invention removes the one-way valve in the main cylinder oil supply channel in the traditional hydraulic system, directly controls the pressure of the main cylinder upper cavity by the servo pump, and eliminates the pressure difference between the main pump outlet pipeline G3 and the main cylinder upper cavity oil way G2. The dynamic valve which is quick in opening and closing time and can ensure the valve core to be reliably seated is adopted, and the high flexibility of the servo pump is matched to realize the timely response of unidirectional control, so that the pressure oscillation is avoided.

The hydraulic system further comprises a small-flow servo pump B3 driven by a servo motor II M2, an outlet of the small-flow servo pump B3 is connected with an inlet of a cartridge valve III CZ3, a hydraulic control port of the cartridge valve III CZ3 is connected with an A port of an electromagnetic directional valve III YV3, a P port of the electromagnetic directional valve III YV3 is connected with an auxiliary oil supply pipe G5, a T port of the electromagnetic directional valve III YV3 is connected with a lower oil tank, the electromagnetic directional valve III YV3 is a D-type two-position four-way electromagnetic directional valve, an outlet of the cartridge valve III CZ3 is connected with the auxiliary oil supply pipe G5, and an outlet of the auxiliary oil supply pipe G5 is connected with a ball valve G4 through a V1; the auxiliary oil supply pipe G5 is connected with an accumulator AC and an accumulator pressure sensor PN2.

Before working, 6MPa of nitrogen is filled into the accumulator AC, and the ball valve V1 is opened; before the sliding block acts, a servo motor II M2 is started, a small-flow servo pump B3 pumps out pressure oil, at the moment, an electromagnetic directional valve III YV3 is powered on, an A port is communicated with a T port, a P port is communicated with a B port, a cartridge valve III CZ3 is opened, an auxiliary oil supply pipe G5 builds pressure and supplements pressure for an accumulator AC, when an accumulator pressure sensor PN2 detects that the pressure of the accumulator AC is 16Mpa, the electromagnetic directional valve III YV3 is powered off to enable the cartridge valve III CZ3 to be closed, and meanwhile, the small-flow servo pump B3 stops supplementing pressure for the accumulator AC, and the auxiliary oil supply pipe G5 and the accumulator AC provide pressure oil for a control oil pipe G4. Because the oil consumption of the control oil is smaller, the invention adopts the small-flow servo pump B3 to supplement the pressure to the accumulator AC, and then utilizes the energy storage function of the accumulator AC to provide the control oil for the system, thereby reducing the starting of the large pump and saving energy.

The outlet of the medium flow servo pump B1 is provided with a pump port pressure sensor PN1 and is connected with the inlet of a dynamic valve C1, the outlet of the dynamic valve C1 is connected with a lower oil tank, a hydraulic control port A of the dynamic valve C1 is connected with an A port of an electromagnetic directional valve YV1 through a throttle valve, a hydraulic control port B of the dynamic valve C1 is connected with a B port of the electromagnetic directional valve YV1 through a throttle valve, a P port of the electromagnetic directional valve YV1 is connected with a control oil pipe G4, and a T port of the electromagnetic directional valve YV1 is connected with the lower oil tank.

The outlet pipeline of the large-flow servo pump B2 is connected with the inlet of a dynamic valve II C2, the outlet of the dynamic valve II C2 is connected with a lower oil tank, the hydraulic control port A of the dynamic valve II C2 is connected with the port A of an electromagnetic directional valve II YV2 through a throttle valve, the hydraulic control port B of the dynamic valve II C2 is connected with the port B of the electromagnetic directional valve II YV2 through a throttle valve, the port P of the electromagnetic directional valve II YV2 is connected with a control oil pipe G4, and the port T of the electromagnetic directional valve II YV2 is connected with the lower oil tank; the electromagnetic directional valve one YV1 and the electromagnetic directional valve two YV2 are D-type two-position four-way electromagnetic directional valves.

When the sliding block moves down or returns quickly, the electromagnetic reversing valve YV1 is electrified, the port P is communicated with the port B, the port A is communicated with the port T, and the dynamic valve C1 is closed quickly; meanwhile, the electromagnetic reversing valve II YV2 is electrified, the port P is communicated with the port B, the port A is communicated with the port T, the dynamic valve II C2 is rapidly closed, and the medium-flow servo pump B1 and the large-flow servo pump B2 work simultaneously, so that the pressure of the main pump outlet pipeline G3 is rapidly built.

When the sliding block is in deceleration and pressurization or pressure maintaining, the electromagnetic directional valve II YV2 is powered off to enable the dynamic valve II C2 to be opened rapidly, the large-flow servo pump B2 stops working, the electromagnetic directional valve I YV1 is kept in a power-on state, and oil is supplied to the main pump outlet pipeline G3 independently by the medium-flow servo pump B1.

When the sliding block is depressurized, the first electromagnetic reversing valve YV1 and the second electromagnetic reversing valve YV2 are powered off simultaneously, and the medium-flow servo pump B1 and the large-flow servo pump B2 do not work.

The outlet pipeline of the medium-flow servo pump B1 is connected with the lower oil tank through a first pressure regulating valve F1, the outlet pipeline of the large-flow servo pump B2 is connected with the lower oil tank through a second pressure regulating valve F2, and the auxiliary oil supply pipe G5 is also connected with the lower oil tank through a third pressure regulating valve F3 and a second ball valve V2 respectively. When the outlet pressure of the middle flow servo pump B1 reaches 25MPa, the first pressure regulating valve F1 is opened to relieve pressure so as to protect the middle flow servo pump B1. When the outlet pressure of the large-flow servo pump B2 reaches 10MPa, the second pressure regulating valve F2 is opened to relieve pressure so as to protect the large-flow servo pump B2. When the pressure of the auxiliary oil supply pipe G5 reaches 16MPa, the pressure regulating valve three F3 is opened for pressure relief so as to protect the safety of the system.

The outlet of the main pump outlet pipeline G3 is connected with the inlet of the cartridge valve eight CZ8, the outlet of the cartridge valve eight CZ8 is connected with the inlet of the cartridge valve nine CZ9, and the outlet of the cartridge valve nine CZ9 is connected with the main cylinder lower cavity oil way G1; the hydraulic control port of the cartridge valve eight CZ8 is connected with the middle outlet of the shuttle valve S1, the right inlet of the shuttle valve S1 is connected with the outlet of the cartridge valve eight CZ8, the left inlet of the shuttle valve S1 is connected with the A port of the electromagnetic directional valve eight YV8, the P port of the electromagnetic directional valve eight YV8 is connected with the inlet of the cartridge valve eight CZ8, the T port of the electromagnetic directional valve eight YV8 is connected with the lower oil tank, and the electromagnetic directional valve eight YV8 is a D-type two-position four-way electromagnetic directional valve; the hydraulic control port of the cartridge valve nine CZ9 is connected with the A port of the electromagnetic directional valve nine YV9, the P port of the electromagnetic directional valve nine YV9 is connected with the outlet of the cartridge valve nine CZ9, the T port of the electromagnetic directional valve nine YV9 is connected with the lower oil tank, and the electromagnetic directional valve nine YV9 is a two-position three-way electromagnetic directional valve; the main cylinder lower cavity oil way G1 is also connected with a lower oil tank through a pressure regulating valve F4.

When the sliding block rapidly descends, is pressurized in a decelerating way or is pressurized in a pressure maintaining way, the electromagnetic directional valve nine YV9 is powered on, the port A is communicated with the port T, the cartridge valve nine CZ9 is opened, the oil in the oil way G1 of the lower cavity of the main cylinder is discharged or the supporting pressure is kept, at the moment, the electromagnetic directional valve eight YV8 is in a power-losing state, the port P is directly communicated with the port A, the port B is directly communicated with the port T, the shuttle valve S1 ensures that the hydraulic control port of the cartridge valve eight CZ8 is pressurized, and the cartridge valve eight CZ8 is in a reliable closing state.

When the sliding block is depressurized, the electromagnetic reversing valve nine YV9 is powered off, and the cartridge valve nine CZ9 is closed.

When the sliding block returns, the electromagnetic directional valve eight YV8 is powered on, the port A is communicated with the port T, the hydraulic control port pressure of the cartridge valve eight CZ8 is lower than the inlet pressure, the cartridge valve eight CZ8 is opened, meanwhile, the electromagnetic directional valve nine YV9 is powered on simultaneously, the cartridge valve nine CZ9 is opened, pressure oil in the main pump outlet pipeline G3 enters the main cylinder lower cavity oil way G1, and the sliding block is driven to move upwards by retracting the piston of the main cylinder 1.

The inlet of the cartridge valve nine CZ9 is connected with the inlet of the cartridge valve five CZ5, the outlet of the cartridge valve five CZ5 is connected with the lower oil tank, the hydraulic control port of the cartridge valve five CZ5 is connected with the A ports of the electromagnetic directional valves five YV5 and YV6, the B port and the T port of the electromagnetic directional valve five are respectively connected with the lower oil tank, the P port of the electromagnetic directional valve five is connected with the lower oil tank through the pressure regulating valve five F5, the A port of the electromagnetic directional valve five is connected with the lower oil tank through the pressure regulating valve six F6, and the electromagnetic directional valve five is a three-position four-way electromagnetic directional valve with the median function of O type.

When the sliding block rapidly descends, the left coil YV6 of the electromagnetic directional valve five is electrified to be at a left station, the hydraulic control port of the cartridge valve five CZ5 is communicated with the oil tank, the cartridge valve five CZ5 is opened, the oil way G1 of the main cylinder lower cavity is directly communicated with the oil tank, and no supporting force of the lower cavity of the main cylinder 1 is realized.

When the sliding block is in deceleration and pressurization or pressure maintaining, the right coil YV5 of the electromagnetic reversing valve five is electrified to be at a right station, the hydraulic control port of the cartridge valve five CZ5 is controlled by the pressure regulating valve five F5, and the back pressure of the lower cavity of the main cylinder 1 is controlled to be 5 MPa-8 MPa by the pressure regulating valve five F5.

When the sliding block is released or returns, the electromagnetic reversing valve five loses electricity and is in the middle position, the hydraulic control port of the cartridge valve five CZ5 is controlled by the pressure regulating valve six F6, and when the upper limit pressure reaches 25MPa, the pressure regulating valve six F6 is opened.

The master cylinder upper cavity oil way G2 is connected with an inlet of a dynamic valve IV C4, an outlet of the dynamic valve IV C4 is connected with an upper oil tank, a hydraulic control port A of the dynamic valve IV C4 is connected with an A port of an electromagnetic reversing valve IV YV4 through a throttle valve, a hydraulic control port B of the dynamic valve IV C4 is connected with a B port of the electromagnetic reversing valve IV YV4 through a throttle valve, a P port of the electromagnetic reversing valve IV YV4 is connected with a control oil pipe G4, a T port of the electromagnetic reversing valve IV YV4 is connected with the upper oil tank, and the electromagnetic reversing valve IV YV4 is a D-type two-position four-way electromagnetic reversing valve; the master cylinder upper chamber oil passage G2 is also connected to an inlet of a proportional valve YAA, and an outlet of the proportional valve YAA is connected to the tank.

When the sliding block rapidly descends or returns, the proportional valve YAA is powered off, the electromagnetic reversing valve four YV4 is powered off, the port P is directly connected with the port A, the port B is directly connected with the port T, the dynamic valve four C4 is rapidly opened, and the upper cavity of the main cylinder 1 is communicated with the upper oil tank; when the sliding block is quickly lowered, the upper oil tank can quickly supplement oil to the upper cavity of the main cylinder; when the sliding block returns, the oil in the upper cavity of the main cylinder can quickly return to the upper oil tank.

When the sliding block is in deceleration and pressurization or pressure maintaining, the proportional valve YAA is powered off and closed, the electromagnetic reversing valve four YV4 is powered on to enable the dynamic valve four C4 to be closed rapidly, and the upper cavity pressure of the main cylinder 1 is directly controlled by the medium flow servo pump B1.

When the pressure maintaining of the sliding block is finished, the proportional valve YAA is powered on firstly to pre-discharge to a certain pressure, then the electromagnetic reversing valve four YV4 is powered off to enable the dynamic valve four C4 to be opened rapidly, the upper cavity of the main cylinder 1 is communicated with the upper oil tank to realize the pressure relief of the sliding block, the proportional valve YAA is controlled by an electric signal in the process to realize the rapid pressure relief and the opening can be controlled to be opened linearly, and therefore the smooth transition from the pressure maintaining of the sliding block to the pressure relief is realized without impact.

As shown in fig. 2, a servo motor M1 is controlled by a servo driver SDR, a three-phase alternating current power supply is connected with a power supply end of the servo driver SDR through a breaker QF1 and a filter EM1, an encoder PG arranged at the tail of the servo motor M1 is connected to a CN1 port of the servo driver SDR, a pump port pressure sensor PN1 is a current feedback pressure sensor and is connected to a CN2 port of the servo driver SDR, a brake resistor R is connected to a brake resistor connecting terminal of the servo driver SDR, an a01 pin of a CN3 port of the servo driver SDR is connected with an aio+ port of an SM231 module of a PLC controller, and an AGND pin of the CN3 port of the servo driver SDR is connected with an AIO-port of an SM231 module of the PLC controller; the CAN communication interface of the servo driver SDR is connected with the CANopen module of the PLC; the servo enabling button SB1 is connected between the starting signal input end S-ON and the V1+ port of the servo driver SDR, and the alarm reset button SB2 is connected between the reset signal input end ALM-RST and the V1+ port of the servo driver SDR; the coil of the relay KA1 is connected between an alarm signal end ALM and a V1-port of the servo driver SDR, and a normally open contact of the relay KA1 is connected in series between a 0.0 port and a V1+ port of an SM223 module of the PLC controller; the coil of the relay two KA2 is connected between the double-pump converging signal input end TGON and the V1-port of the servo driver SDR, and the normally open contact of the relay two KA2 is connected in series between the 0.1 port and the V1+ port of the SM223 module of the PLC controller; the CPU of the PLC is connected with the touch screen PM1 through an Ethernet communication line, the port of V1 is connected with +24VDC, and the port of V1 is grounded; the servo driver SDR adopts a ProNet-2BDIB Esston servo driver, and the PLC controller adopts Siemens 6ES7215-1BG40-0XB0 type.

The servo driver SDR acquires a digital signal sent by the encoder PG and precisely controls the operation of a servo motor M1; after receiving a pump port pressure signal sent by a pump port pressure sensor PN1, a servo driver SDR converts the pump port pressure signal into an analog signal controlled by 0-10v pressure and sends the analog signal to an SM223 module of a PLC (programmable logic controller) through a CN3 port, and after comparing the pressure signal, the PLC sends a control signal to a CAN communication interface of the servo driver SDR through a CANopen module, and the servo driver SDR selectively adopts flow control or PID to adjust and control oil pressure; the method changes the traditional adopted flow and pressure control to set 0-10V analog signals as digital bus control, adopts a CANOpen protocol to communicate in an industrial environment with stronger interference through a CAN communication interface, and solves the problem that the remote transmission of the analog signals is easy to be interfered; the servo controller can be arranged close to the servo motor, the motor cable is shortened, and meanwhile, servo operation information and alarm content can be displayed in a picture of the touch screen after being transmitted through a bus.

When the slide block rapidly descends, the main pump outlet pipeline G3 is not pressurized, the servo driver SDR controls the operation of the servo motor M1 by using the flow, and the large-flow servo pump B2 and the medium-flow servo pump B1 supply oil together.

When the slide block is used for decelerating and pressurizing or maintaining pressure, the main pump outlet pipeline G3 is already pressurized and is independently supplied with oil by the middle flow servo pump B1, the pump port pressure sensor PN1 feeds back the pressure of the outlet of the middle flow servo pump B1 to the servo driver SDR in real time, the high response of the servo motor M1 is combined, the flow output of the middle flow servo pump B1 is regulated, the servo driver SDR adopts PID to regulate and control the oil pressure of the main pump outlet pipeline G3, stable pressurization can be realized, overshoot is avoided, the accuracy of pressure control is ensured, and deformation which can not restore parts is avoided. The pump port pressure sensor PN1 adopts a current feedback pressure sensor, so that the electric noise interference can be solved, and the diagnosis when the line is broken or the power supply is not connected is facilitated.

After a servo enabling button SB1 is pressed, a servo driver SDR is started, when the pressure of a main pump outlet pipeline G3 is lower than 10MPa, a coil of a relay two KA2 is powered on, a normally open contact of the relay two KA2 is closed, a PLC receives a double-pump confluence signal, an electromagnetic reversing valve two YV2 is powered on, a dynamic valve two C2 is rapidly closed, and a large-flow servo pump B2 and a medium-flow servo pump B1 supply oil simultaneously.

When the servo driver SDR detects faults such as overcurrent, a coil of the relay KA1 is electrified, a normally open contact of the relay KA1 is closed, the PLC receives an alarm signal, the PLC prompts the alarm signal on the touch screen PM1 through an Ethernet communication wire, and an alarm reset button SB2 is pressed down to reset the alarm.

The invention adopts a hydraulic processing method of a hydraulic system of a hydraulic machine, and each working cycle sequentially comprises the following actions: automatic pressure supplementing of an energy accumulator: firstly, 6MPa of nitrogen is filled into an accumulator AC, a second servo motor M2 is started and an electromagnetic reversing valve three YV3 is electrified before a sliding block acts, and a small-flow servo pump B3 pumps out pressure oil to supplement the pressure of the accumulator AC;

the pressure supplementing of the energy accumulator is stopped: when the charging pressure of the accumulator AC reaches 16Mpa, the electromagnetic reversing valve three YV3 is powered off to close the cartridge valve three CZ3, and the small-flow servo pump B3 is stopped;

the sliding block rapidly descends: the electromagnetic directional valve nine YV9 is powered on to enable the cartridge valve nine CZ9 to be opened, the electromagnetic directional valve five is switched to the left station to enable the cartridge valve five CZ5 to be opened, and oil in the lower cavity of the main cylinder is directly communicated with the oil return tank; the electromagnetic directional valve one YV1 and the electromagnetic directional valve two YV2 are powered on simultaneously, the large-flow servo pump B2 and the medium-flow servo pump B1 supply oil together, the electromagnetic directional valve seven YV7 is powered on to enable the dynamic valve seven C7 to be opened rapidly, oil enters the upper cavity of the main cylinder, meanwhile, the electromagnetic directional valve four YV4 is powered off to enable the dynamic valve four C4 to be opened rapidly, and oil in the upper oil tank is fed into the upper cavity of the main cylinder rapidly along with the rapid descending of the sliding block;

fourth, the slide block is decelerated and pressurized: the second electromagnetic reversing valve YV2 is powered off to enable the second dynamic valve C2 to be opened rapidly, the first electromagnetic reversing valve YV1 is kept powered on, and the medium-flow servo pump B1 is used for independently supplying oil; the electromagnetic reversing valve four YV4 is electrified to enable the dynamic valve four C4 to be rapidly closed, the pressure of the upper cavity of the main cylinder is directly controlled by the medium-flow servo pump B1, the electromagnetic reversing valve five is switched to the right station, and the pressure of the lower cavity of the main cylinder is controlled by the pressure regulating valve five F5;

Maintaining pressure of the sliding block: the state of each valve is kept for a period of time, and the flow servo pump B1 controls the pressure of the pressure maintaining;

sixth step of sliding block pressure relief: the proportional valve YAA is powered on firstly, and the pressure of the upper cavity of the main cylinder is pre-relieved; then the electromagnetic directional valve one YV1, the electromagnetic directional valve four YV4, the electromagnetic directional valve five, the electromagnetic directional valve seven YV7 and the electromagnetic directional valve nine YV9 are all powered off, and the sliding block can completely release pressure;

slide return: the electromagnetic directional valve one YV1 and the electromagnetic directional valve two YV2 are powered simultaneously, the large-flow servo pump B2 and the medium-flow servo pump B1 supply oil together, the electromagnetic directional valve eight YV8 is powered to open the cartridge valve eight CZ8, the electromagnetic directional valve nine YV9 is powered to open the cartridge valve nine CZ9, pressure oil enters the lower cavity of the main cylinder, and the main cylinder drives the sliding block to move upwards; the proportional valve YAA is powered off and closed, the electromagnetic directional valve seven YV7 is powered off to keep the dynamic valve seven C7 closed, the electromagnetic directional valve four YV4 is powered off to keep the dynamic valve four C4 open, and oil in the upper cavity of the master cylinder can quickly return to the upper oil tank;

stopping: all the electromagnetic directional valves are powered off, and the servo motor is stopped.

The small-flow servo pump B3 is adopted to carry out liquid filling and pressure supplementing on the energy accumulator AC, so as to provide control oil for the system, reduce the starting of the large-flow servo pump and save energy; the large-flow servo pump B2 is only used for supplying oil when the sliding block is fast down or returns, so that the energy consumption can be further reduced, and the equipment failure rate is reduced. The one-way valve in the main cylinder oil supply channel in the traditional hydraulic system is removed, the servo pump directly controls the pressure of the main cylinder upper cavity, and the pressure difference between the main pump outlet pipeline G3 and the main cylinder upper cavity oil way G2 is eliminated, so that the control precision is higher; the pressure maintaining pressure is controlled by the flow servo pump B1, overflow is not needed, and the oil temperature is reduced; the dynamic valve which is quick in opening and closing time and can ensure the valve core to be reliably seated is adopted, and the high flexibility of the servo pump is matched to realize the timely response of unidirectional control, so that the pressure oscillation is avoided. And when the pressure maintaining is finished, the pressure is released in advance through the proportional valve YAA, so that the impact-free pressure release is realized, and the smooth transition from the pressure maintaining of the sliding block to the pressure release is realized.

When the slide block rapidly descends, the main pump outlet pipeline G3 is not pressurized, and the servo driver SDR controls the operation of a servo motor M1 by using the flow; when the slide block is used for decelerating and pressurizing or maintaining pressure, the main pump outlet pipeline G3 is already pressurized and is independently supplied with oil by the middle flow servo pump B1, the pump port pressure sensor PN1 feeds back the pressure of the outlet of the middle flow servo pump B1 to the servo driver SDR in real time, the high response of the servo motor M1 is combined, the flow output of the middle flow servo pump B1 is regulated, and the servo driver SDR adopts PID to regulate and control the oil pressure of the main pump outlet pipeline G3, so that stable pressurization is realized and overshoot is avoided; when the sliding block is depressurized, the proportional valve YAA is controlled through an electric signal, so that the rapid pressure relief can be realized, the opening can be controlled to be opened linearly, no impact is realized, and the smooth transition from the pressure maintaining to the pressure relief of the sliding block is realized. The servo driver SDR adopts two modes of flow control and PID regulation control to switch, so that stable pressurization of the sliding block can be realized, the accuracy of pressure control is ensured, and the deformation of the parts, which cannot be recovered due to pressurization overshoot, is avoided. And the pressure relief can not cause great impact noise and loosening of the fixing piece.

The foregoing description is only of a preferred embodiment of the invention and is not intended to limit the scope of the invention. In addition to the embodiments described above, other embodiments of the invention are possible. All technical schemes formed by equivalent substitution or equivalent transformation fall within the protection scope of the invention. The technical features of the present invention that are not described may be implemented by or using the prior art, and are not described herein.

Claims

1. The utility model provides a precision pressure control system of servo pump accuse hydraulic press, includes master cylinder (1) of installing in the slider top, and the lower chamber of master cylinder (1) links to each other with master cylinder lower chamber oil circuit (G1), and the upper chamber of master cylinder (1) links to each other with master cylinder upper chamber oil circuit (G2), its characterized in that: the hydraulic control system further comprises a medium-flow servo pump (B1) and a high-flow servo pump (B2) which are driven by a first servo motor (M1) together, wherein the outlet of the medium-flow servo pump (B1) is connected with the inlet of a first cartridge valve (CZ 1), the outlet of the high-flow servo pump (B2) is connected with the inlet of a second cartridge valve (CZ 2), the hydraulic control ports of the first cartridge valve (CZ 1) and the second cartridge valve (CZ 2) are respectively connected with the respective outlets, the outlets of the first cartridge valve (CZ 1) and the second cartridge valve (CZ 2) are both connected with a main pump outlet pipeline (G3), the main pump outlet pipeline (G3) is connected with the inlet of a dynamic valve seven (C7), the outlet of the dynamic valve seven (C7) is connected with an oil way (G2) of a main cylinder upper cavity, the hydraulic control port A of the dynamic valve seven (C7) is connected with the A port of an electromagnetic reversing valve seven (YV 7) through a throttle valve, the hydraulic control port B of the dynamic valve seven (C7) is connected with the electromagnetic reversing valve (YV 7) through the seven throttle valve and the B of the electromagnetic reversing valve (YV 7) is connected with the reversing valve Y7;

The outlet of the medium flow servo pump (B1) is provided with a pump port pressure sensor (PN 1) and is connected with the inlet of a dynamic valve I (C1), the outlet of the dynamic valve I (C1) is connected with a lower oil tank, a hydraulic control port A of the dynamic valve I (C1) is connected with an A port of an electromagnetic directional valve I (YV 1) through a throttle valve, a hydraulic control port B of the dynamic valve I (C1) is connected with a B port of the electromagnetic directional valve I (YV 1) through a throttle valve, a P port of the electromagnetic directional valve I (YV 1) is connected with a control oil pipe (G4), and a T port of the electromagnetic directional valve I (YV 1) is connected with the lower oil tank; the outlet pipeline of the large-flow servo pump (B2) is connected with the inlet of a dynamic valve II (C2), the outlet of the dynamic valve II (C2) is connected with a lower oil tank, the hydraulic control port A of the dynamic valve II (C2) is connected with the A port of an electromagnetic directional valve II (YV 2) through a throttle valve, the hydraulic control port B of the dynamic valve II (C2) is connected with the B port of the electromagnetic directional valve II (YV 2) through a throttle valve, the P port of the electromagnetic directional valve II (YV 2) is connected with a control oil liquid pipe (G4), and the T port of the electromagnetic directional valve II (YV 2) is connected with the lower oil tank; the electromagnetic directional valve I (YV 1) and the electromagnetic directional valve II (YV 2) are D-type two-position four-way electromagnetic directional valves;

the outlet of the main pump outlet pipeline (G3) is connected with the inlet of a cartridge valve eight (CZ 8), the outlet of the cartridge valve eight (CZ 8) is connected with the inlet of a cartridge valve nine (CZ 9), and the outlet of the cartridge valve nine (CZ 9) is connected with a main cylinder lower cavity oil way (G1); the hydraulic control port of the cartridge valve eight (CZ 8) is connected with the middle outlet of the shuttle valve (S1), the right inlet of the shuttle valve (S1) is connected with the outlet of the cartridge valve eight (CZ 8), the left inlet of the shuttle valve (S1) is connected with the A port of the electromagnetic directional valve eight (YV 8), the P port of the electromagnetic directional valve eight (YV 8) is connected with the inlet of the cartridge valve eight (CZ 8), the T port of the electromagnetic directional valve eight (YV 8) is connected with the lower oil tank, and the electromagnetic directional valve eight (YV 8) is a D-type two-position four-way electromagnetic directional valve; the hydraulic control port of the cartridge valve nine (CZ 9) is connected with the A port of the electromagnetic directional valve nine (YV 9), the P port of the electromagnetic directional valve nine (YV 9) is connected with the outlet of the cartridge valve nine (CZ 9), the T port of the electromagnetic directional valve nine (YV 9) is connected with the lower oil tank, and the electromagnetic directional valve nine (YV 9) is a two-position three-way electromagnetic directional valve; the main cylinder lower cavity oil way (G1) is also connected with a lower oil tank through a pressure regulating valve IV (F4);

The master cylinder upper cavity oil way (G2) is connected with an inlet of a dynamic valve IV (C4), an outlet of the dynamic valve IV (C4) is connected with an upper oil tank, a hydraulic control port A of the dynamic valve IV (C4) is connected with an A port of an electromagnetic reversing valve IV (YV 4) through a throttle valve, a hydraulic control port B of the dynamic valve IV (C4) is connected with a B port of the electromagnetic reversing valve IV (YV 4) through a throttle valve, a P port of the electromagnetic reversing valve IV (YV 4) is connected with a control oil pipe (G4), a T port of the electromagnetic reversing valve IV (YV 4) is connected with the upper oil tank, and the electromagnetic reversing valve IV (YV 4) is a D-type two-position four-way electromagnetic reversing valve; the main cylinder upper cavity oil way (G2) is also connected with an inlet of a proportional valve (YAA), and an outlet of the proportional valve (YAA) is connected with an oil tank;

when the sliding block rapidly descends: the electromagnetic directional valve nine (YV 9) is powered on to open the cartridge valve nine (CZ 9), the electromagnetic directional valve five is switched to the left station to open the cartridge valve five (CZ 5), and oil in the lower cavity of the main cylinder is directly communicated with the oil return tank; the electromagnetic directional valve I (YV 1) and the electromagnetic directional valve II (YV 2) are powered on simultaneously, the large-flow servo pump (B2) and the medium-flow servo pump (B1) supply oil together, the electromagnetic directional valve seven (YV 7) is powered on to enable the dynamic valve seven (C7) to be opened rapidly, oil enters the upper cavity of the main cylinder, meanwhile, the electromagnetic directional valve IV (YV 4) is powered off to enable the dynamic valve IV (C4) to be opened rapidly, and oil in the upper oil tank is fed into the upper cavity of the main cylinder rapidly along with the rapid descending of the sliding block;

When the slide block is decelerated and pressurized: the second electromagnetic reversing valve (YV 2) is powered off to enable the second dynamic valve (C2) to be opened rapidly, the first electromagnetic reversing valve (YV 1) is kept powered on, and the medium-flow servo pump (B1) is used for independently supplying oil; the electromagnetic reversing valve IV (YV 4) is electrified to enable the dynamic valve IV (C4) to be rapidly closed, the pressure of the upper cavity of the main cylinder is directly controlled by the medium-flow servo pump (B1), the electromagnetic reversing valve V is switched to the right station, and the pressure regulating valve V (F5) is used for controlling the supporting pressure of the lower cavity of the main cylinder.

2. The precision pressure control system of a servo pump controlled hydraulic machine of claim 1, wherein: the hydraulic control device is characterized by further comprising a small-flow servo pump (B3) driven by a servo motor II (M2), wherein the outlet of the small-flow servo pump (B3) is connected with the inlet of a cartridge valve III (CZ 3), the hydraulic control port of the cartridge valve III (CZ 3) is connected with the A port of an electromagnetic reversing valve III (YV 3), the P port of the electromagnetic reversing valve III (YV 3) is connected with an auxiliary oil supply pipe (G5), the T port of the electromagnetic reversing valve III (YV 3) is connected with a lower oil tank, the electromagnetic reversing valve III (YV 3) is a D-type two-position four-way electromagnetic reversing valve, the outlet of the cartridge valve III (CZ 3) is connected with an auxiliary oil supply pipe (G5), and the outlet of the auxiliary oil supply pipe (G5) is connected with a control oil pipe (G4) through a ball valve I (V1); the auxiliary oil supply pipe (G5) is connected with an energy Accumulator (AC) and an energy accumulator pressure sensor (PN 2).

3. The precision pressure control system of a servo pump controlled hydraulic machine of claim 2, wherein: the outlet pipeline of the medium flow servo pump (B1) is connected with the lower oil tank through a first pressure regulating valve (F1), the outlet pipeline of the large flow servo pump (B2) is connected with the lower oil tank through a second pressure regulating valve (F2), and the auxiliary oil supply pipe (G5) is also connected with the lower oil tank through a third pressure regulating valve (F3) and a second ball valve (V2) respectively.

4. The precision pressure control system of a servo pump controlled hydraulic machine of claim 1, wherein: the inlet of the cartridge valve III (CZ 9) is connected with the inlet of the cartridge valve V (CZ 5), the outlet of the cartridge valve V (CZ 5) is connected with the lower oil tank, the hydraulic control port of the cartridge valve V (CZ 5) is connected with the A port of the electromagnetic directional valve V (YV 5, YV 6), the B port and the T port of the electromagnetic directional valve V are respectively connected with the lower oil tank, the P port of the electromagnetic directional valve V is connected with the lower oil tank through the pressure regulating valve V (F5), the A port of the electromagnetic directional valve V is connected with the lower oil tank through the pressure regulating valve V (F6), and the electromagnetic directional valve V is a three-position four-way electromagnetic directional valve with the median function of O.

5. The precision pressure control system of a servo pump controlled hydraulic machine of claim 1, wherein: the servo motor I (M1) is controlled by a Servo Driver (SDR), a three-phase alternating current power supply is connected with a power end of the Servo Driver (SDR) through a breaker (QF 1) and a filter (EM 1), an encoder (PG) arranged at the tail of the servo motor I (M1) is connected to a CN1 port of the Servo Driver (SDR), a pump port pressure sensor (PN 1) is a current feedback pressure sensor and is connected to a CN2 port of the Servo Driver (SDR), an A01 pin of a CN3 port of the Servo Driver (SDR) is connected with an AIO+ port of an SM231 module of the PLC, and an AGND pin of a CN3 port of the Servo Driver (SDR) is connected with an AIO-port of an SM231 module of the PLC; the CAN communication interface of the Servo Driver (SDR) is connected with the CANopen module of the PLC; the servo enabling button (SB 1) is connected between a starting signal input end (S-ON) of the Servo Driver (SDR) and the V1+ port, and the alarm reset button (SB 2) is connected between a reset signal input end (ALM-RST) of the Servo Driver (SDR) and the V1+ port; the coil of the relay I (KA 1) is connected between an alarm signal end (ALM) of a Servo Driver (SDR) and a V1-port, and a normally open contact of the relay I (KA 1) is connected in series between a 0.0 port and a V1+ port of an SM223 module of the PLC controller; the coil of the relay II (KA 2) is connected between the double-pump converging signal input end (TGON) of the Servo Driver (SDR) and the V1-port, and the normally open contact of the relay II (KA 2) is connected in series between the 0.1 port and the V1+ port of the SM223 module of the PLC controller; the CPU of the PLC is connected with the touch screen (PM 1) through an Ethernet communication line, the port of V1 < + > is connected with +24VDC, and the port of V1 < + > is grounded; the Servo Driver (SDR) adopts a ProNet-2BDIB Esston servo driver, and the PLC controller adopts Siemens 6ES7215-1BG40-0XB0 type.

6. A method of hydraulic machining using the precision pressure control system of the servo pump controlled hydraulic machine of claim 5, characterized by: each duty cycle comprises the following actions in turn:

automatic pressure supplementing of an energy accumulator: firstly, 6MPa of nitrogen is filled into an Accumulator (AC), before the sliding block acts, a servo motor II (M2) is started, an electromagnetic reversing valve III (YV 3) is electrified, and a small-flow servo pump (B3) pumps out pressure oil to supplement pressure of the Accumulator (AC);

the pressure supplementing of the energy accumulator is stopped: when the charging pressure of the Accumulator (AC) reaches 16Mpa, the electromagnetic reversing valve III (YV 3) is powered off to close the cartridge valve III (CZ 3), and the small-flow servo pump (B3) is stopped;

the sliding block rapidly descends: the electromagnetic directional valve nine (YV 9) is powered on to open the cartridge valve nine (CZ 9), the electromagnetic directional valve five is switched to the left station to open the cartridge valve five (CZ 5), and oil in the lower cavity of the main cylinder is directly communicated with the oil return tank; the electromagnetic directional valve I (YV 1) and the electromagnetic directional valve II (YV 2) are powered on simultaneously, the large-flow servo pump (B2) and the medium-flow servo pump (B1) supply oil together, the electromagnetic directional valve seven (YV 7) is powered on to enable the dynamic valve seven (C7) to be opened rapidly, oil enters the upper cavity of the main cylinder, meanwhile, the electromagnetic directional valve IV (YV 4) is powered off to enable the dynamic valve IV (C4) to be opened rapidly, and oil in the upper oil tank is fed into the upper cavity of the main cylinder rapidly along with the rapid descending of the sliding block;

Fourth, the slide block is decelerated and pressurized: the second electromagnetic reversing valve (YV 2) is powered off to enable the second dynamic valve (C2) to be opened rapidly, the first electromagnetic reversing valve (YV 1) is kept powered on, and the medium-flow servo pump (B1) is used for independently supplying oil; the electromagnetic directional valve IV (YV 4) is powered on to enable the dynamic valve IV (C4) to be closed rapidly, the pressure of the upper cavity of the main cylinder is directly controlled by the medium-flow servo pump (B1), the electromagnetic directional valve IV is switched to the right station, and the pressure regulating valve IV (F5) is used for controlling the supporting pressure of the lower cavity of the main cylinder;

maintaining pressure of the sliding block: the state of each valve is kept for a period of time, and the flow servo pump (B1) controls the pressure of the maintaining pressure;

sixth step of sliding block pressure relief: the proportional valve (YAA) is powered on firstly, and the pressure of the upper cavity of the main cylinder is pre-relieved; then the first electromagnetic directional valve (YV 1), the fourth electromagnetic directional valve (YV 4), the fifth electromagnetic directional valve, the seventh electromagnetic directional valve (YV 7) and the ninth electromagnetic directional valve (YV 9) are all powered off, and the sliding block can completely release pressure;

slide return: the electromagnetic directional valve I (YV 1) and the electromagnetic directional valve II (YV 2) are powered on simultaneously, the large-flow servo pump (B2) and the medium-flow servo pump (B1) are used for supplying oil together, the electromagnetic directional valve eight (YV 8) is powered on to enable the cartridge valve eight (CZ 8) to be opened, the electromagnetic directional valve nine (YV 9) is powered on to enable the cartridge valve nine (CZ 9) to be opened, pressure oil enters a lower cavity of the main cylinder, and the main cylinder drives the sliding block to ascend; the proportional valve (YAA) is powered off, the electromagnetic directional valve seven (YV 7) is powered off to keep the dynamic valve seven (C7) closed, the electromagnetic directional valve four (YV 4) is powered off to keep the dynamic valve four (C4) open, and oil in the upper cavity of the master cylinder can quickly return to the upper oil tank;

7. The method of hydraulic machining by a precision pressure control system of a servo pump controlled hydraulic machine of claim 6, wherein: when the slide block rapidly descends, the main pump outlet pipeline (G3) is not pressurized, and the Servo Driver (SDR) controls the operation of the servo motor I (M1) by using the flow; when the sliding block is used for decelerating and pressurizing or maintaining pressure, the main pump outlet pipeline (G3) is already pressurized and is independently supplied with oil by the middle flow servo pump (B1), the pump port pressure sensor (PN 1) feeds back the pressure of the outlet of the middle flow servo pump (B1) to the Servo Driver (SDR) in real time, the high response of the servo motor I (M1) is combined, the flow output of the middle flow servo pump (B1) is regulated, and the Servo Driver (SDR) adopts PID to regulate and control the oil pressure of the main pump outlet pipeline (G3) so as to realize stable pressurization and avoid overshoot; when the sliding block is depressurized, the proportional valve (YAA) is controlled through an electric signal, so that the rapid depressurization can be realized, the opening can be controlled to be opened linearly, no impact is realized, and the smooth transition from the pressure maintaining to the pressure relief of the sliding block is realized.