阅读说明：本技术 一种六面顶压机液压系统及压力控制方法 (Hydraulic system of cubic press and pressure control method ) 是由 张彬 庞昊红 王晨阳 杜欢龙 韩长余 曹克科 于 2021-09-30 设计创作，主要内容包括：本发明的目的是提供一种六面顶压机液压系统及压力控制方法,用于提供一种大缸径六面顶压机的超高压油路、配套低压及控制油路和基于该液压系统的压力控制方法,该液压油路采用往复式增压器提供超高压液压油,采用步进电机卸压模块进行直接卸压；该控制方法能够精准控制液压系统的油压,实现六面顶压机的长时间稳定运行和安全平稳卸压。(The invention aims to provide a hydraulic system of a cubic press and a pressure control method, which are used for providing an ultrahigh pressure oil circuit, a matched low pressure and control oil circuit of a large-cylinder-diameter cubic press and a pressure control method based on the hydraulic system, wherein the hydraulic oil circuit adopts a reciprocating type supercharger to provide ultrahigh pressure hydraulic oil, and adopts a stepping motor pressure relief module to directly relieve pressure; the control method can accurately control the oil pressure of the hydraulic system, and realizes long-time stable operation and safe and stable pressure relief of the cubic press.)

1. The hydraulic system of the cubic press is characterized in that: the main oil way comprises a main pipeline, and an oil tank, a large oil pump, a small oil pump, a straight-through check valve group, a three-position four-way electromagnetic reversing valve, a superposed throttle valve, a first two-position four-way electromagnetic reversing valve, an ultrahigh-pressure hydraulic control check valve and a working cylinder which are sequentially arranged on the main pipeline; the direct check valve group comprises a first direct check valve and a second direct check valve, and oil paths of the large oil pump and the small oil pump respectively pass through the first direct check valve and the second direct check valve and then are connected in parallel to the main pipeline to provide hydraulic oil for the hydraulic system; one way and two ways of the three-position four-way electromagnetic directional valve are communicated with the main pipeline, the three ways are communicated with a branch oil pipe of a return cavity of the working cylinder, and the four ways are communicated with an oil tank; one way and two ways of the first two-position four-way electromagnetic directional valve are communicated with the main pipeline, and the three way is communicated with the oil tank; the electric motor is used for providing power for the oil pump; the system also comprises an electromagnetic overflow valve used for adjusting the pressure of the system, wherein the oil inlet end of the electromagnetic overflow valve is connected to a main oil path between the through one-way valve bank and the three-position four-way electromagnetic directional valve, and the oil outlet end of the electromagnetic overflow valve is communicated with an oil tank; the system also comprises a second two-position four-way electromagnetic reversing valve for controlling the on-off of the ultrahigh pressure hydraulic control one-way valve, wherein one way and two ways of the second two-position four-way electromagnetic reversing valve are respectively connected with a low-pressure rodless cavity and a low-pressure rod cavity of the ultrahigh pressure hydraulic control one-way valve, the three way is communicated with an oil tank, and the four way is communicated with a main oil way between the straight-through one-way valve group and the three-position four-way electromagnetic reversing valve; the low-pressure gauge and the low-pressure sensor are arranged on a pipeline between the second two-position four-way electromagnetic directional valve and the through one-way valve group; the system also comprises a high-pressure gauge and a high-pressure sensor, wherein the high-pressure gauge and the high-pressure sensor are arranged on a main oil path between the ultrahigh-pressure hydraulic control one-way valve and the working cavity of the working cylinder; the two-position seven-way valve is arranged on a main oil path between the ultrahigh pressure hydraulic control one-way valve and the working cylinder working cavity; the three-position four-way electromagnetic reversing valve is characterized by also comprising a third two-position four-way electromagnetic reversing valve for controlling the on-off of the two-position seven-way valve, wherein one way and two ways of the third two-position four-way electromagnetic reversing valve are respectively connected with a low-pressure rodless cavity and a low-pressure rod cavity of the two-position seven-way valve, the three way is communicated with an oil tank, and the four way is communicated with a main oil way between the straight-through check valve group and the three-position four-way electromagnetic reversing valve; the oil inlet end of the overflow valve is connected to an oil pipe of a return cavity of the working cylinder, and the oil outlet end of the overflow valve is communicated with an oil tank; the system comprises a large oil pump, a small oil pump, a PLC and a high-pressure sensor, and is characterized by further comprising the first motor and the second motor, wherein the first motor and the second motor are respectively used for controlling the operation of the large oil pump and the small oil pump, the PLC is used for controlling the start and stop of the first motor and the second motor, the power off of the electromagnet in each electromagnetic valve, and receiving signals sent by the high-pressure sensor and the low-pressure sensor.

2. A cubic press hydraulic system as set forth in claim 1, wherein: the superposed throttle valves, the first two-position four-way electromagnetic reversing valve, the ultrahigh pressure hydraulic control one-way valve and the working cylinders in the main oil way are 6 groups, and the 6 groups of superposed throttle valves, the first two-position four-way electromagnetic reversing valve, the ultrahigh pressure hydraulic control one-way valve and the working cylinders are connected in parallel on the main oil way respectively in the same connection mode; the tee joints of the first two-position four-way electromagnetic reversing valve in the 6 groups are connected in parallel and then communicated with an oil tank; and 6 groups of low-pressure rodless cavities of the ultrahigh-pressure hydraulic control one-way valves are connected in parallel and then communicated with a first way of the second two-position four-way electromagnetic reversing valve, and low-pressure rod cavities of the ultrahigh-pressure hydraulic control one-way valves are connected in parallel and then communicated with a second way of the second two-position four-way electromagnetic reversing valve.

3. A cubic press hydraulic system as set forth in claim 1, wherein: the system also comprises an overpressure oil path, wherein the overpressure oil path comprises an electromagnetic on-off valve and a reciprocating supercharger; one end of the electromagnetic on-off valve is connected to a main oil path between the straight-through one-way valve group and the three-position four-way electromagnetic reversing valve, and the other end of the electromagnetic on-off valve is connected to the oil inlet end of the reciprocating supercharger; the oil outlet end of the reciprocating supercharger is connected with the two-position seven-way valve, and the oil return end of the reciprocating supercharger is communicated with the oil tank.

4. A cubic press hydraulic system as set forth in claim 1, wherein: the pressure relief oil path comprises a fourth two-position four-way electromagnetic reversing valve, an ultrahigh pressure hydraulic control on-off valve, a stepping unloading valve and an ultrahigh pressure manual on-off valve; one way and two ways of the fourth two-position four-way electromagnetic directional valve are respectively connected with a control oil path port of the ultrahigh pressure hydraulic control on-off valve, the three ways are communicated with a main oil path between the through one-way valve group and the three-position four-way electromagnetic directional valve, and the four ways are communicated with an oil tank; the ultrahigh pressure hydraulic control on-off valve is connected with the ultrahigh pressure manual on-off valve in parallel, the oil inlet end is connected between the two-position seven-way valve and the reciprocating supercharger, and the oil outlet end is connected with the oil inlet end of the stepping unloading valve; the oil outlet end of the stepping unloading valve is connected with an oil tank.

5. A cubic press hydraulic system as set forth in claim 2, wherein: the working cylinder comprises a limiting working cylinder and an unlimited working cylinder.

6. A cubic press hydraulic system as set forth in claim 5, wherein: the number of the limiting working cylinders is 3, and the number of the non-limiting working cylinders is 3.

7. A cubic press hydraulic system as set forth in claim 5, wherein: the non-limiting working cylinder is further provided with a proximity switch for detecting the blocking position of the working cylinder, and the PLC is used for receiving signals sent by the proximity switch.

8. A pressure control method using a cubic press hydraulic system as set forth in claim 1, characterized in that: the method comprises the following steps:

s1: preparation before work: opening a control program, setting parameters of pause time, charging pressure, holding pressure time, pressure relief rate, return pressure and return time, adjusting an electromagnetic overflow valve, an overflow valve, a superposition type throttle valve, the flow of a large oil pump, the flow of a small oil pump, a limit ring of a limit working cylinder and a proximity switch of a non-limit working cylinder to meet working requirements, adjusting a top hammer, and adjusting the control program to enter an automatic working state;

s2: idle stroke advancing: starting a working program and starting a free-wheeling advancing process step; the large oil pump motor is started, the large oil pump works to pump hydraulic oil out of an oil tank and inject the hydraulic oil into a main pipeline through a straight-through check valve, an electromagnet in the electromagnetic overflow valve is electrified, then the electromagnetic overflow valve stabilizes the pressure of a low-pressure oil circuit system to be near a set value, redundant hydraulic oil overflows from an overflow port of the electromagnetic overflow valve and returns to an oil tank, an electromagnet 2CT of the three-position four-way electromagnetic directional valve is electrified, an electromagnet corresponding to a first two-position four-way electromagnetic directional valve of a non-limiting working cylinder is electrified, redundant hydraulic oil in a return cavity of the non-limiting working cylinder returns to the oil tank through the three-position four-way electromagnetic directional valve, meanwhile, the hydraulic oil in the main pipeline flows to branch oil pipes corresponding to the three non-limiting working cylinders after passing through the three-position four-way electromagnetic directional valve, flows through the first two-position four-way electromagnetic directional valve through a corresponding superposed throttle valve, and then flows into working cavities of the three non-limiting working cylinders through an ultrahigh pressure hydraulic control check valve, pushing the plunger to drive the cushion block, the top hammer and the like to advance;

s3: pausing: the proximity switch on the non-limiting working cylinder detects that the corresponding plunger moves forward to the right position, the two-position four-way electromagnetic reversing valve of the non-limiting working cylinder is correspondingly controlled to be powered off, and the plunger stops moving forward; when the plungers of the 3 movable working cylinders are all in place, the control program automatically enters a pause step;

s4: liquid filling: when the pause time reaches the set time, the program automatically enters the liquid filling step; the first motor of the large oil pump is controlled to start, the system pressure generated in the low-pressure oil path after the electromagnet in the electromagnetic overflow valve is electrified enables the electromagnet 2CT of the three-position four-way electromagnetic directional valve to be electrified, the electromagnet corresponding to the first two-position four-way electromagnetic directional valve to be electrified, hydraulic oil enters the working cavities of the six working cylinders, the electromagnet of the third two-position four-way electromagnetic directional valve is electrified, the two-position seven-way valve is pushed to work, the working cavities of the six working cylinders are in a communicated state, the plunger is pushed with the same oil pressure to drive the cushion block, the top hammer and the like to advance, and the compression of the synthetic block in six directions is realized;

s5: overpressure: when the high-pressure sensor detects that the pressure in the working cylinder reaches the set liquid filling pressure, ending the liquid filling step and entering the overpressure step; the electromagnet 2CT of the three-position four-way electromagnetic reversing valve and the electromagnets 3-8CT of the 6 first two-position four-way electromagnetic reversing valves are powered off, and hydraulic oil in an oil pipe between the three-position four-way electromagnetic reversing valve and the ultrahigh pressure hydraulic control one-way valve returns to an oil tank through the three-position four-way electromagnetic reversing valve and the first two-position four-way electromagnetic reversing valves; meanwhile, an electromagnet of the electromagnetic on-off valve is electrified, hydraulic oil enters the reciprocating type supercharger, and ultrahigh-pressure hydraulic oil generated by the operation of the reciprocating type supercharger enters working cavities of six working cylinders through the two-position seven-way valve, so that the hydraulic oil pressure of the six working cylinders is synchronously lifted;

s6: pressure maintaining: when the high-pressure sensor detects that the pressure of the ultrahigh pressure area reaches the set pressure maintaining pressure, the overpressure is over, the large oil pump motor stops working, the electromagnet 10CT of the electromagnetic overflow valve and the electromagnet 12CT of the electromagnetic on-off valve are powered off, and the pressure maintaining step is started; the electromagnet of the third two-position four-way electromagnetic reversing valve is electrified, so that the communication state of the working cavities of the six working cylinders is kept, and the pressure in six directions of the cubic press is equal in the pressure maintaining process;

s7: pressure relief: when the pressure maintaining time reaches the set setting, the pressure maintaining is finished, and the pressure relief is started; when the low-pressure sensor detects that the oil pressure of a low-pressure oil path exceeds the lowest oil pressure capable of opening the ultrahigh-pressure hydraulic control on-off valve, the electromagnet of the fourth two-position four-way electromagnetic reversing valve is electrified, hydraulic oil in the main pipeline passes through the fourth two-position four-way electromagnetic reversing valve, the ultrahigh-pressure hydraulic air on-off valve is pushed to work, the ultrahigh-pressure relief channel is opened, and the ultrahigh-pressure hydraulic oil reaches the stepping unloading valve; by opening the ultrahigh pressure liquid-air on-off valve, the PLC controls the step motor to work to drive the valve core of the step unloading valve to rotate step by step, and the pressure is directly relieved from the ultrahigh pressure area according to the set pressure relief parameters; in the pressure relief process, when the high-pressure sensor detects that the actual oil pressure of the ultrahigh pressure area is lower than the pressure relief setting parameter by 3MPa, the electromagnet 13CT of the fourth two-position four-way electromagnetic directional valve is powered off, the ultrahigh pressure liquid-air on-off valve is closed in an emergency, and until the high-pressure sensor detects that the pressure relief setting parameter is equal to the actual oil pressure of the ultrahigh pressure area, the electromagnet 13CT of the fourth two-position four-way electromagnetic directional valve is electrified, the ultrahigh pressure liquid control on-off valve is opened, and pressure relief is continued;

s8: and (3) return stroke: when the high-pressure sensor detects that the oil pressure in the working cylinder reaches the set return pressure, ending pressure relief and starting return; the small oil pump motor stops working, the large oil pump motor is started, the electromagnet 11CT of the third two-position four-way electromagnetic reversing valve and the electromagnet 13CT of the fourth two-position four-way electromagnetic reversing valve are powered off, the two-position seven-way valve returns to the original position, and the working cavities of the six working cylinders are disconnected; the ultrahigh pressure hydraulic control on-off valve controls the hydraulic oil in the oil pipe of the oil way to automatically return to the oil tank through the fourth two-position four-way electromagnetic reversing valve, and the ultrahigh pressure hydraulic control on-off valve returns; the electromagnet 1CT of the three-position four-way electromagnetic directional valve is electrified, the electromagnet of the second two-position four-way electromagnetic directional valve is electrified, and the electromagnet in the electromagnetic overflow valve is electrified, so that hydraulic oil in the main pipeline passes through the two-position four-way electromagnetic directional valve, the ultrahigh-pressure hydraulic control one-way valve is pushed to work, a hydraulic oil return channel in a working cavity of the working cylinder is opened, and the hydraulic oil in the working cavity of the working cylinder returns to the oil tank from the first two-position four-way electromagnetic directional valve; meanwhile, after passing through the three-position four-way electromagnetic directional valve, hydraulic oil in the main pipeline is reduced to a preset value under the action of the overflow valve and then is injected into a return cavity of the working cylinder to push the plunger to return; meanwhile, the stepping motor drives the stepping unloading valve to rotate towards the direction of the original point until the system detects that the stepping motor reaches the original point, and the stepping motor rotates reversely by a certain angle until the unloading valve returns to the original position;

s9: and finishing one working cycle: when the return time reaches the set time, the large oil pump motor stops working, all the electromagnets are not electrified, the three-position four-way electromagnetic directional valve is positioned at the middle position, and the hydraulic oil in the return cavity of the working cylinder automatically returns to the oil tank through a middle position overflow hole of the three-position four-way electromagnetic directional valve until the pressure of the hydraulic oil in the return cavity returns to zero; the ultrahigh pressure hydraulic control one-way valve controls hydraulic oil in an oil pipe of the oil way to automatically return to the oil tank through the second two-position four-way electromagnetic reversing valve, the ultrahigh pressure hydraulic control one-way valve returns to the original position, and the pressure of the hydraulic oil in the oil pipe returns to zero; the equipment stops working and one synthesis cycle is finished.

9. The pressure control method of a cubic press hydraulic system as set forth in claim 8, wherein: the pressure maintaining step is also provided with a step of automatic pressure compensation under low pressure and automatic pressure relief under high pressure, and the pressure compensation action in the pressure maintaining step is specifically as follows: in the pressure maintaining process, if the high-pressure sensor detects that the pressure of the ultrahigh pressure area is lower than the set pressure maintaining pressure by 0.3MPa, the small oil pump motor is started, the electromagnet 10CT of the electromagnetic overflow valve, the electromagnet 11CT of the third two-position four-way electromagnetic reversing valve and the electromagnet 12CT of the electromagnetic on-off valve are electrified, the ultrahigh pressure area is subjected to pressure compensation until the actual pressure reaches the set pressure maintaining pressure, the motor stops running, the electromagnet 10CT of the electromagnetic overflow valve and the electromagnet 12CT of the electromagnetic on-off valve are powered off, and the pressure compensation is finished.

10. The pressure control method of a cubic press hydraulic system as set forth in claim 1, characterized in that: when the cubic press needs to be adjusted, maintained or in emergency, the operation is required to be carried out in the adjustment working state; the adjustment of the working state comprises the following steps:

s1: single-cylinder advance: when the single-cylinder forward operation is carried out in the adjustment working state, a large oil pump motor is started, an electromagnet of the electromagnetic overflow valve is electrified, an electromagnet 2CT of the three-position four-way electromagnetic directional valve and an electromagnet of the three-position four-way electromagnetic directional valve corresponding to the corresponding working cylinder are electrified, and hydraulic oil enters a working cavity of the corresponding working cylinder to push the plunger to move forward;

s2: pressure relief/return stroke: when pressure relief/return operation is carried out in an adjustment working state, if a high-pressure sensor detects that the oil pressure of the ultrahigh pressure area is higher than a set return pressure, a program executes a pressure relief action until the oil pressure of the ultrahigh pressure area is relieved to the return pressure, and then a return action is executed; if the oil pressure of the ultrahigh pressure area is less than or equal to the set return pressure, the program directly executes the return action;

s3: emergency pressure relief: when special conditions are met, the ultrahigh pressure area of the cubic press needs to be quickly relieved, the small oil pump motor is started, the electromagnet of the electromagnetic overflow valve is electrified, and the electromagnet of the third two-position four-way electromagnetic directional valve is electrified, so that the ultrahigh pressure area is ensured to be in a communicated state; an electromagnet of the fourth two-position four-way electromagnetic reversing valve is electrified, and the PLC controls the stepping motor to rotate at a certain angle quickly to drive the valve core of the stepping unloading valve to open to a certain degree quickly so as to start emergency pressure relief; when the oil pressure of the ultrahigh pressure area is reduced to be lower than the return pressure, the return operation can be carried out, and the return action is switched to.

Technical Field

The invention belongs to the technical field of hydraulic pressure, and particularly relates to a hydraulic system of a cubic press and a pressure control method.

Background

The size of the synthesis cavity is crucial to diamond production, and because the temperature and pressure difference inevitably exists in the synthesis cavity, the increase of the synthesis cavity not only means the increase of the overall growth space of diamond in one-time synthesis, but also represents the reduction of the pressure and temperature gradient in the synthesis environment, which is more beneficial to abrasive-grade diamond and cultured diamond, and for large-particle diamond, the size of the synthesis cavity directly restricts the growth upper limit of the diamond. Since the beginning of the diamond industry, the large-scale synthesis press has been one of the main targets of research and development of diamond production related enterprises due to the requirements of cost and production quality.

Along with the increase of the cavity of the synthetic press, the oil filling amount of hydraulic oil in the working cylinder is greatly increased; meanwhile, with the market demand of high-grade artificial diamonds, particularly artificial cultured diamonds, the synthesis process time is greatly prolonged, uncertain internal leakage factors exist in the synthesis process, and particularly, the reason is difficult to find due to slight internal leakage faults of a high-pressure area, so that the demand of hydraulic oil in the synthesis process is high. The traditional supercharger has limited high-pressure oil supply, has the problem of supercharger overtravel, and can not meet the production requirement.

The reciprocating supercharger is a special crystal growth device for long process developed in recent years, and the utility model patent CN201120363620.3 and the utility model patent CN201820221608.0 respectively disclose a hydraulic diagram and a working principle of the reciprocating supercharger, so that super high pressure oil can be continuously provided as long as low pressure oil is continuously provided, and the problem of supercharger overtravel can be effectively avoided; in addition, as long as the ultrahigh voltage area does not have serious internal leakage, the internal leakage of the low voltage area of the equipment can be ignored.

In the pressure relief stage, the pressure relief effect of the synthetic press can be achieved only by relieving the pressure of a high-pressure oil way of about 20MPa due to the existence of a supercharger, the pressure can be directly relieved only from an ultrahigh pressure area of more than 100MPa by adopting a reciprocating supercharger, and the pressure is too high, the oil way is complex, the control difficulty is high, and the stability is poor. Therefore, the direct pressure relief of the ultrahigh pressure is a necessary crossing gate in the process of the large-scale press. The invention patent CN202010921687.8 discloses a control method for safe pressure relief of an ultrahigh pressure hydraulic oil way, which can realize stable pressure relief of a cubic press in a normal working state.

In order to ensure the stable operation and safe pressure relief of the cubic press, a hydraulic system and a control system of the cubic press need to be further improved, and particularly, the protection measures for abnormal conditions in the pressure relief process need to be further improved.

Disclosure of Invention

In order to solve the problems, the invention provides a hydraulic system of a cubic press and a pressure control method, wherein a reciprocating type supercharger is adopted in a hydraulic oil path to provide ultrahigh pressure hydraulic oil, and a stepping motor pressure relief module is adopted to directly relieve pressure from an ultrahigh pressure area; the control method can accurately control the oil pressure of the hydraulic system and realize long-time stable operation and stable pressure relief of the cubic press.

The technical scheme for solving the technical problems of the invention is as follows:

a hydraulic system of a cubic press comprises a main oil way, wherein the main oil way comprises a main pipeline, and an oil tank, a large oil pump, a small oil pump, a through one-way valve bank, a three-position four-way electromagnetic reversing valve, a superposed throttle valve, a first two-position four-way electromagnetic reversing valve, an ultrahigh-pressure hydraulic control one-way valve and a working cylinder which are sequentially arranged on the main pipeline; the direct check valve group comprises a first direct check valve and a second direct check valve, and oil paths of the large oil pump and the small oil pump respectively pass through the first direct check valve and the second direct check valve and then are connected in parallel to the main pipeline to provide hydraulic oil for the hydraulic system; one way and two ways of the three-position four-way electromagnetic directional valve are communicated with the main pipeline, the three ways are communicated with a branch oil pipe of a return cavity of the working cylinder, and the four ways are communicated with an oil tank; one way and two ways of the first two-position four-way electromagnetic directional valve are communicated with the main pipeline, and the three way is communicated with the oil tank; the electric motor is used for providing power for the oil pump; the system also comprises an electromagnetic overflow valve used for adjusting the pressure of the system, wherein the oil inlet end of the electromagnetic overflow valve is connected to a main oil path between the through one-way valve bank and the three-position four-way electromagnetic directional valve, and the oil outlet end of the electromagnetic overflow valve is communicated with an oil tank; the system also comprises a second two-position four-way electromagnetic reversing valve for controlling the on-off of the ultrahigh pressure hydraulic control one-way valve, wherein one way and two ways of the second two-position four-way electromagnetic reversing valve are respectively connected with a low-pressure rodless cavity and a low-pressure rod cavity of the ultrahigh pressure hydraulic control one-way valve, the three way is communicated with an oil tank, and the four way is communicated with a main oil way between the straight-through one-way valve group and the three-position four-way electromagnetic reversing valve; the low-pressure gauge and the low-pressure sensor are arranged on a pipeline between the second two-position four-way electromagnetic directional valve and the through one-way valve group; the system also comprises a high-pressure gauge and a high-pressure sensor, wherein the high-pressure gauge and the high-pressure sensor are arranged on a main oil path between the ultrahigh-pressure hydraulic control one-way valve and the working cavity of the working cylinder; the two-position seven-way valve is arranged on a main oil path between the ultrahigh pressure hydraulic control one-way valve and the working cylinder working cavity; the three-position four-way electromagnetic reversing valve is characterized by also comprising a third two-position four-way electromagnetic reversing valve for controlling the on-off of the two-position seven-way valve, wherein one way and two ways of the third two-position four-way electromagnetic reversing valve are respectively connected with a low-pressure rodless cavity and a low-pressure rod cavity of the two-position seven-way valve, the three way is communicated with an oil tank, and the four way is communicated with a main oil way between the straight-through check valve group and the three-position four-way electromagnetic reversing valve; the oil inlet end of the overflow valve is connected to an oil pipe of a return cavity of the working cylinder, and the oil outlet end of the overflow valve is communicated with an oil tank; the system comprises a large oil pump, a small oil pump, a PLC and a high-pressure sensor, and is characterized by further comprising the first motor and the second motor, wherein the first motor and the second motor are respectively used for controlling the operation of the large oil pump and the small oil pump, the PLC is used for controlling the start and stop of the first motor and the second motor, the power off of the electromagnet in each electromagnetic valve, and receiving signals sent by the high-pressure sensor and the low-pressure sensor.

The superposed throttle valves, the first two-position four-way electromagnetic reversing valve, the ultrahigh pressure hydraulic control one-way valve and the working cylinders in the main oil way are 6 groups, and the 6 groups of superposed throttle valves, the first two-position four-way electromagnetic reversing valve, the ultrahigh pressure hydraulic control one-way valve and the working cylinders are connected in parallel on the main oil way respectively in the same connection mode; the tee joints of the first two-position four-way electromagnetic reversing valve in the 6 groups are connected in parallel and then communicated with an oil tank; and 6 groups of low-pressure rodless cavities of the ultrahigh-pressure hydraulic control one-way valves are connected in parallel and then communicated with a first way of the second two-position four-way electromagnetic reversing valve, and low-pressure rod cavities of the ultrahigh-pressure hydraulic control one-way valves are connected in parallel and then communicated with a second way of the second two-position four-way electromagnetic reversing valve.

The system also comprises an overpressure oil path, wherein the overpressure oil path comprises an electromagnetic on-off valve and a reciprocating supercharger; one end of the electromagnetic on-off valve is connected to a main oil path between the straight-through one-way valve group and the three-position four-way electromagnetic reversing valve, and the other end of the electromagnetic on-off valve is connected to the oil inlet end of the reciprocating supercharger; the oil outlet end of the reciprocating supercharger is connected with the two-position seven-way valve, and the oil return end of the reciprocating supercharger is communicated with the oil tank.

The pressure relief oil path comprises a fourth two-position four-way electromagnetic reversing valve, an ultrahigh pressure hydraulic control on-off valve, a stepping unloading valve and an ultrahigh pressure manual on-off valve; one way and two ways of the fourth two-position four-way electromagnetic directional valve are respectively connected with a control oil path port of the ultrahigh pressure hydraulic control on-off valve, the three ways are communicated with a main oil path between the through one-way valve group and the three-position four-way electromagnetic directional valve, and the four ways are communicated with an oil tank; the ultrahigh pressure hydraulic control on-off valve is connected with the ultrahigh pressure manual on-off valve in parallel, the oil inlet end is connected between the two-position seven-way valve and the reciprocating supercharger, and the oil outlet end is connected with the oil inlet end of the stepping unloading valve; the oil outlet end of the stepping unloading valve is connected with an oil tank.

The working cylinder comprises a limiting working cylinder and an unlimited working cylinder.

The number of the limiting working cylinders is 3, and the number of the non-limiting working cylinders is 3.

The non-limiting working cylinder is further provided with a proximity switch for detecting the blocking position of the working cylinder, and the PLC is used for receiving signals sent by the proximity switch.

A pressure control method using a hydraulic system of a cubic press is characterized by comprising the following steps: the method comprises the following steps:

s1: preparation before work: opening a control program, setting parameters of pause time, charging pressure, holding pressure time, pressure relief rate, return pressure and return time, adjusting an electromagnetic overflow valve, an overflow valve, a superposition type throttle valve, the flow of a large oil pump, the flow of a small oil pump, a limit ring of a limit working cylinder and a proximity switch of a non-limit working cylinder to meet working requirements, adjusting a top hammer, and adjusting the control program to enter an automatic working state;

s2: idle stroke advancing: starting a working program and starting a free-wheeling advancing process step; the large oil pump motor is started, the large oil pump works to pump hydraulic oil out of an oil tank and inject the hydraulic oil into a main pipeline through a straight-through check valve, an electromagnet in the electromagnetic overflow valve is electrified, then the electromagnetic overflow valve stabilizes the pressure of a low-pressure oil circuit system to be near a set value, redundant hydraulic oil overflows from an overflow port of the electromagnetic overflow valve and returns to an oil tank, an electromagnet 2CT of the three-position four-way electromagnetic directional valve is electrified, an electromagnet corresponding to a first two-position four-way electromagnetic directional valve of a non-limiting working cylinder is electrified, redundant hydraulic oil in a return cavity of the non-limiting working cylinder returns to the oil tank through the three-position four-way electromagnetic directional valve, meanwhile, the hydraulic oil in the main pipeline flows to branch oil pipes corresponding to the three non-limiting working cylinders after passing through the three-position four-way electromagnetic directional valve, flows through the first two-position four-way electromagnetic directional valve through a corresponding superposed throttle valve, and then flows into working cavities of the three non-limiting working cylinders through an ultrahigh pressure hydraulic control check valve, pushing the plunger to drive the cushion block, the top hammer and the like to advance;

s3: pausing: the proximity switch on the non-limiting working cylinder detects that the corresponding plunger moves forward to the right position, the two-position four-way electromagnetic reversing valve of the non-limiting working cylinder is correspondingly controlled to be powered off, and the plunger stops moving forward; when the plungers of the 3 movable working cylinders are all in place, the control program automatically enters a pause step;

s4: liquid filling: when the pause time reaches the set time, the program automatically enters the liquid filling step; the first motor of the large oil pump is controlled to start, the system pressure generated in the low-pressure oil path after the electromagnet in the electromagnetic overflow valve is electrified enables the electromagnet 2CT of the three-position four-way electromagnetic directional valve to be electrified, the electromagnet corresponding to the first two-position four-way electromagnetic directional valve to be electrified, hydraulic oil enters the working cavities of the six working cylinders, the electromagnet of the third two-position four-way electromagnetic directional valve is electrified, the two-position seven-way valve is pushed to work, the working cavities of the six working cylinders are in a communicated state, the plunger is pushed with the same oil pressure to drive the cushion block, the top hammer and the like to advance, and the compression of the synthetic block in six directions is realized;

s5: overpressure: when the high-pressure sensor detects that the pressure in the working cylinder reaches the set liquid filling pressure, ending the liquid filling step and entering the overpressure step; the electromagnet 2CT of the three-position four-way electromagnetic reversing valve and the electromagnets 3-8CT of the 6 first two-position four-way electromagnetic reversing valves are powered off, and hydraulic oil in an oil pipe between the three-position four-way electromagnetic reversing valve and the ultrahigh pressure hydraulic control one-way valve returns to an oil tank through the three-position four-way electromagnetic reversing valve and the first two-position four-way electromagnetic reversing valves; meanwhile, an electromagnet of the electromagnetic on-off valve is electrified, hydraulic oil enters the reciprocating type supercharger, and ultrahigh-pressure hydraulic oil generated by the operation of the reciprocating type supercharger enters working cavities of six working cylinders through the two-position seven-way valve, so that the hydraulic oil pressure of the six working cylinders is synchronously lifted;

s6: pressure maintaining: when the high-pressure sensor detects that the pressure of the ultrahigh pressure area reaches the set pressure maintaining pressure, the overpressure is over, the large oil pump motor stops working, the electromagnet 10CT of the electromagnetic overflow valve and the electromagnet 12CT of the electromagnetic on-off valve are powered off, and the pressure maintaining step is started; the electromagnet of the third two-position four-way electromagnetic reversing valve is electrified, so that the communication state of the working cavities of the six working cylinders is kept, and the pressure in six directions of the cubic press is equal in the pressure maintaining process;

s7: pressure relief: when the pressure maintaining time reaches the set setting, the pressure maintaining is finished, and the pressure relief is started; when the low-pressure sensor detects that the oil pressure of a low-pressure oil path exceeds the lowest oil pressure capable of opening the ultrahigh-pressure hydraulic control on-off valve, the electromagnet of the fourth two-position four-way electromagnetic reversing valve is electrified, hydraulic oil in the main pipeline passes through the fourth two-position four-way electromagnetic reversing valve, the ultrahigh-pressure hydraulic air on-off valve is pushed to work, the ultrahigh-pressure relief channel is opened, and the ultrahigh-pressure hydraulic oil reaches the stepping unloading valve; through opening the ultrahigh pressure liquid-air on-off valve, the PLC controls the work of the stepping motor to drive the valve core of the stepping unloading valve to rotate step by step, and the pressure is directly released from the ultrahigh pressure area according to the set pressure releasing parameters. In the pressure relief process, when the high-pressure sensor detects that the actual oil pressure of the ultrahigh pressure area is lower than the pressure relief setting parameter by 3MPa, the electromagnet 13CT of the fourth two-position four-way electromagnetic directional valve is powered off, the ultrahigh pressure liquid-air on-off valve is closed in an emergency, and until the high-pressure sensor detects that the pressure relief setting parameter is equal to the actual oil pressure of the ultrahigh pressure area, the electromagnet 13CT of the fourth two-position four-way electromagnetic directional valve is electrified, the ultrahigh pressure liquid control on-off valve is opened, and pressure relief is continued;

s8: and (3) return stroke: when the high-pressure sensor detects that the oil pressure in the working cylinder reaches the set return pressure, ending pressure relief and starting return; the small oil pump motor stops working, the large oil pump motor is started, the electromagnet 11CT of the third two-position four-way electromagnetic reversing valve and the electromagnet 13CT of the fourth two-position four-way electromagnetic reversing valve are powered off, the two-position seven-way valve returns to the original position, and the working cavities of the six working cylinders are disconnected; and the ultrahigh pressure hydraulic control on-off valve controls the hydraulic oil in the oil pipe of the oil way to automatically return to the oil tank through the fourth two-position four-way electromagnetic reversing valve, and the ultrahigh pressure hydraulic control on-off valve returns. The electromagnet 1CT of the three-position four-way electromagnetic directional valve is electrified, the electromagnet of the second two-position four-way electromagnetic directional valve is electrified, and the electromagnet in the electromagnetic overflow valve is electrified, so that hydraulic oil in the main pipeline passes through the two-position four-way electromagnetic directional valve, the ultrahigh-pressure hydraulic control one-way valve is pushed to work, a hydraulic oil return channel in a working cavity of the working cylinder is opened, and the hydraulic oil in the working cavity of the working cylinder returns to the oil tank from the first two-position four-way electromagnetic directional valve; meanwhile, after passing through the three-position four-way electromagnetic directional valve, hydraulic oil in the main pipeline is reduced to a preset value under the action of the overflow valve and then is injected into a return cavity of the working cylinder to push the plunger to return; meanwhile, the stepping motor drives the stepping unloading valve to rotate towards the direction of the original point until the system detects that the stepping motor reaches the original point, and the stepping motor rotates reversely by a certain angle until the unloading valve returns to the original position;

s9: and finishing one working cycle: when the return time reaches the set time, the large oil pump motor stops working, all the electromagnets are not electrified, the three-position four-way electromagnetic directional valve is positioned at the middle position, and the hydraulic oil in the return cavity of the working cylinder automatically returns to the oil tank through a middle position overflow hole of the three-position four-way electromagnetic directional valve until the pressure of the hydraulic oil in the return cavity returns to zero; the ultrahigh pressure hydraulic control one-way valve controls hydraulic oil in an oil pipe of the oil way to automatically return to the oil tank through the second two-position four-way electromagnetic reversing valve, the ultrahigh pressure hydraulic control one-way valve returns to the original position, and the pressure of the hydraulic oil in the oil pipe returns to zero; the equipment stops working and one synthesis cycle is finished.

The pressure maintaining step is also provided with a step of automatic pressure compensation under low pressure and automatic pressure relief under high pressure, and the pressure compensation action in the pressure maintaining step is specifically as follows: in the pressure maintaining process, if the high-pressure sensor detects that the pressure of the ultrahigh pressure area is lower than the set pressure maintaining pressure by 0.3MPa, the small oil pump motor is started, the electromagnet 10CT of the electromagnetic overflow valve, the electromagnet 11CT of the third two-position four-way electromagnetic reversing valve and the electromagnet 12CT of the electromagnetic on-off valve are electrified, the ultrahigh pressure area is subjected to pressure compensation until the actual pressure reaches the set pressure maintaining pressure, the motor stops running, the electromagnet 10CT of the electromagnetic overflow valve and the electromagnet 12CT of the electromagnetic on-off valve are powered off, and the pressure compensation is finished.

When the cubic press needs to be adjusted, maintained or in emergency, the operation is required to be carried out in the adjustment working state; the adjustment of the working state comprises the following steps:

s1: single-cylinder advance: when the single-cylinder forward operation is carried out in the adjustment working state, a large oil pump motor is started, an electromagnet of the electromagnetic overflow valve is electrified, an electromagnet 2CT of the three-position four-way electromagnetic directional valve and an electromagnet of the three-position four-way electromagnetic directional valve corresponding to the corresponding working cylinder are electrified, and hydraulic oil enters a working cavity of the corresponding working cylinder to push the plunger to move forward;

s2: pressure relief/return stroke: when pressure relief/return operation is carried out in an adjustment working state, if a high-pressure sensor detects that the oil pressure of the ultrahigh pressure area is higher than a set return pressure, a program executes a pressure relief action until the oil pressure of the ultrahigh pressure area is relieved to the return pressure, and then a return action is executed; if the oil pressure of the ultrahigh pressure area is less than or equal to the set return pressure, the program directly executes the return action;

s3: emergency pressure relief: when special conditions are met, the ultrahigh pressure area of the cubic press needs to be quickly relieved, the small oil pump motor is started, the electromagnet of the electromagnetic overflow valve is electrified, and the electromagnet of the third two-position four-way electromagnetic directional valve is electrified, so that the ultrahigh pressure area is ensured to be in a communicated state; an electromagnet of the fourth two-position four-way electromagnetic reversing valve is electrified, and the PLC controls the stepping motor to rotate at a certain angle quickly to drive the valve core of the stepping unloading valve to open to a certain degree quickly so as to start emergency pressure relief; when the oil pressure of the ultrahigh pressure area is reduced to be lower than the return pressure, the return operation can be carried out, and the return action is switched to.

The invention has the beneficial effects that:

1. the invention provides a hydraulic system of a large-cylinder-diameter cubic press, wherein a reciprocating type supercharger is adopted in a hydraulic oil path to provide ultrahigh-pressure hydraulic oil, so that the use amount of the hydraulic oil is greatly reduced, and the over-travel problem of the traditional supercharger is effectively avoided; the direct safe pressure relief of the ultrahigh pressure area is realized by adopting the pressure relief module of the stepping motor.

2. The invention provides a control method of a hydraulic system, which can accurately control the oil pressure of the hydraulic system and realize long-time stable operation and stable pressure relief of a cubic press.

Drawings

FIG. 1 is a schematic diagram of a hydraulic system of the present invention.

Fig. 2 is a schematic diagram of the on-off of the electromagnet and the motor in the process step corresponding to the automatic working state and the adjustment working state of the invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

As shown in fig. 1, the hydraulic system of the cubic press comprises a main oil path, wherein the main oil path comprises a main pipeline, an oil tank 1, a large oil pump 2, a small oil pump 3, a straight-through check valve bank, a three-position four-way electromagnetic directional valve 14, a superposed throttle valve 18-23, a first two-position four-way electromagnetic directional valve 24-29, an ultrahigh pressure hydraulic control check valve 30-35 and a working cylinder which are sequentially arranged on the main pipeline; the direct check valve group comprises a first direct check valve 6 and a second direct check valve 7, and oil paths of the large oil pump 2 and the small oil pump 3 respectively pass through the first direct check valve 6 and the second direct check valve 7 and then are connected in parallel to the main pipeline to provide hydraulic oil for the hydraulic system; one way and two ways of the three-position four-way electromagnetic directional valve 14 are communicated with the main pipeline, the three ways are communicated with a branch oil pipe of a return cavity of the working cylinder, and the four ways are communicated with the oil tank 1; one way and two ways of the first two-position four-way electromagnetic directional valve 24-29 are communicated with the main pipeline, and the three way is communicated with the oil tank 1; the electric motor is used for providing power for the oil pump; the system is characterized by further comprising an electromagnetic overflow valve 12 for adjusting system pressure, wherein the oil inlet end of the electromagnetic overflow valve 12 is connected to a main oil path between the through one-way valve bank and the three-position four-way electromagnetic directional valve 14, and the oil outlet end of the electromagnetic overflow valve 12 is communicated with the oil tank 1; the system is characterized by further comprising a second two-position four-way electromagnetic reversing valve 15 for controlling the on-off of the ultrahigh pressure hydraulic control one-way valve 30-35, wherein one way and two ways of the second two-position four-way electromagnetic reversing valve 15 are respectively connected with a low-pressure rodless cavity and a low-pressure rod cavity of the ultrahigh pressure hydraulic control one-way valve 30-35, the three ways are communicated with the oil tank 1, and the four ways are communicated with a main oil way between the straight-through one-way valve group and the three-position four-way electromagnetic reversing valve 14; the low-pressure gauge 8 and the low-pressure sensor 10 are arranged on a pipeline between the second two-position four-way electromagnetic directional valve 15 and the straight-through one-way valve group; the system also comprises a high-pressure gauge 9 and a high-pressure sensor 11, wherein the high-pressure gauge 9 and the high-pressure sensor 11 are arranged on a main oil path between the ultrahigh-pressure hydraulic control one-way valve 30-35 and the working cavity of the working cylinder; the hydraulic control system also comprises a two-position seven-way valve 17 for controlling the on-off of the working cavities of the six working cylinders, wherein the two-position seven-way valve 17 is arranged on a main oil path between the ultrahigh pressure hydraulic control one-way valves 30-35 and the working cavities of the working cylinders; the three-position four-way electromagnetic reversing valve is characterized by further comprising a third two-position four-way electromagnetic reversing valve 16 for controlling the on-off of the two-position seven-way valve 17, wherein one way and two ways of the third two-position four-way electromagnetic reversing valve 16 are respectively connected with a low-pressure rodless cavity and a low-pressure rod cavity of the two-position seven-way valve 17, the three way is communicated with the oil tank 1, and the four way is communicated with a main oil way between the straight-through one-way valve group and the three-position four-way electromagnetic reversing valve 14; the oil return device also comprises an overflow valve 13 used for adjusting return pressure, wherein the oil inlet end of the overflow valve 13 is connected to an oil branch pipe of a return cavity of the working cylinder, and the oil outlet end of the overflow valve 13 is communicated with the oil tank 1; still include first motor 4, second motor 5, first motor 4, second motor 5 are used for controlling the operation of big oil pump 2, little oil pump 3 respectively, still include PLC, PLC is used for controlling the start-stop of first motor 4, second motor 5, the area outage of electro-magnet in each solenoid valve to and receive the signal that high pressure sensor 11, low pressure sensor 10 sent.

The superposed throttle valves 18-23, the first two-position four-way electromagnetic reversing valve 24-29, the ultrahigh pressure hydraulic control one-way valve 30-35 and the working cylinders in the main oil way are 6 groups, and the 6 groups of superposed throttle valves 18-23, the first two-position four-way electromagnetic reversing valve 24-29, the ultrahigh pressure hydraulic control one-way valve 30-35 and the working cylinders are connected in parallel on the main oil way respectively in the same connection mode; the tee joints of the first two-position four-way electromagnetic directional valves 24-29 in the 6 groups are connected in parallel and then communicated with the oil tank 1; and the low-pressure rodless cavities of the ultrahigh-pressure hydraulic control check valves 30-35 in the 6 groups are connected in parallel and then communicated with the first way of the second two-position four-way electromagnetic reversing valve 15, and the low-pressure rod cavities are connected in parallel and then communicated with the second way of the second two-position four-way electromagnetic reversing valve 15.

The device also comprises an overpressure oil path, wherein the overpressure oil path comprises an electromagnetic on-off valve 48 and a reciprocating supercharger 49; one end of the electromagnetic on-off valve 48 is connected to a main oil path between the through one-way valve set and the three-position four-way electromagnetic directional valve 14, and the other end of the electromagnetic on-off valve is connected to the oil inlet end of the reciprocating supercharger 49; the oil outlet end of the reciprocating supercharger 49 is connected with the two-position seven-way valve 17, and the oil return end of the reciprocating supercharger 49 is communicated with the oil tank 1.

The pressure relief oil path comprises a fourth two-position four-way electromagnetic directional valve 51, an ultrahigh pressure hydraulic control on-off valve 52, a stepping unloading valve 54 and an ultrahigh pressure manual on-off valve 53; one way and two ways of the fourth two-position four-way electromagnetic directional valve 51 are respectively connected with a control oil path port of the ultrahigh pressure hydraulic control on-off valve 52, the three ways are communicated with a main oil path between the through one-way valve group and the three-position four-way electromagnetic directional valve 14, and the four ways are communicated with the oil tank 1; the ultrahigh pressure hydraulic control on-off valve 52 is connected with the ultrahigh pressure manual on-off valve 53 in parallel, the oil inlet end is connected between the two-position seven-way valve 17 and the reciprocating supercharger 49, and the oil outlet end is connected with the oil inlet end of the stepping unloading valve 54; the oil outlet end of the stepping unloading valve 54 is connected with the oil tank 1.

The working cylinders include limiting working cylinders 36-38 and non-limiting working cylinders 39-41.

The number of the limiting working cylinders 36-38 is 3, and the number of the non-limiting working cylinders 39-41 is 3.

The unlimited working cylinders 39-41 are also provided with proximity switches for detecting the blocking positions of the working cylinders, and the PLC is used for receiving signals sent by the proximity switches.

As shown in fig. 2, the operation states of the pressure control method of the hydraulic system include an automatic operation state and a regulation operation state.

The automatic state working process comprises the following steps:

preparation before work: opening a control program, setting parameters such as pause time, liquid filling pressure, pressure maintaining time, pressure relief rate, return pressure, return time and the like, adjusting the electromagnetic overflow valve 12, the overflow valve 13, the superposed throttle valves 18-23, the flow of the large oil pump 2, the flow of the small oil pump 3, the limiting rings of the three limiting working cylinders 42-44 and the proximity switches (JJ1-JJ3) of the three non-limiting working cylinders 45-47 to meet the working requirements, adjusting the 6 top hammers, and adjusting the control program to enter an automatic working state.

Idle stroke advancing: and starting a working program and starting the idle stroke advancing process step. The large oil pump motor 4 is started, the large oil pump 2 works to pump hydraulic oil out of the oil tank 1 and inject the hydraulic oil into the main pipeline through the through one-way valve 6, the electromagnetic overflow valve stabilizes the pressure of a low-pressure oil way system near a set value after an electromagnet (10CT) in the electromagnetic overflow valve 12 is electrified, redundant hydraulic oil overflows from an oil return tank through an overflow port of the electromagnetic overflow valve, so that the electromagnet (2CT) of the three-position four-way electromagnetic directional valve 14 is electrified, electromagnets (6CT, 7CT and 8CT) corresponding to the two-position four-way electromagnetic directional valves (27, 28 and 29) are electrified, redundant hydraulic oil in return cavities of working cylinders (39, 40 and 41) can return to the oil tank through the three-position four-way electromagnetic directional valve, meanwhile, the hydraulic oil in the main pipeline flows to branch oil pipes corresponding to the three non-limiting working cylinders (39, 40 and 41) after passing through the three-position four-way electromagnetic directional valve, and passes through the superposition type throttle valve (21, 22. 23) flows through two-position four-way electromagnetic directional valves (27, 28, 29), then flows into working chambers of three unlimited working cylinders through ultrahigh-pressure hydraulic control one-way valves (33, 34, 35), and pushes plungers (45, 46, 47) to drive cushion blocks, top hammers and the like to advance.

Pausing: when the proximity switch (JJ1/JJ2/JJ3) detects that the corresponding plunger (45/46/47) advances to the right position, the corresponding two-position four-way electromagnetic directional valve (27/28/29) is powered off, and the plunger stops advancing; when the plungers of the 3 movable working cylinders are all in place, the control program automatically enters a pause step.

Liquid filling: when the pause time reaches the set time, the program automatically enters the liquid filling step. The large oil pump motor 4 is started, the electromagnet (10CT) in the electromagnetic overflow valve 12 is electrified, then the system pressure generated in the low-pressure oil path enables the electromagnet (2CT) of the three-position four-way electromagnetic directional valve 14 to be electrified, the electromagnets (3CT-8CT) corresponding to the two-position four-way electromagnetic directional valves 24-29 to be electrified, hydraulic oil enters the working cavities of the six working cylinders 36-41, the electromagnet (11CT) of the two-position four-way electromagnetic directional valve 16 is electrified, the two-position seven-way valve 17 is pushed to work, the working cavities of the six working cylinders are in a communicated state, the plungers 42-47 are pushed by the same oil pressure to drive the cushion blocks, the top hammers and the like to advance, and compression of the synthetic block in six directions is achieved.

Overpressure: and when the high-pressure sensor 11 detects that the pressure in the working cylinder reaches the set liquid filling pressure, ending the liquid filling step and entering the overpressure step. When the power of the 2CT-8CT is cut off, the hydraulic oil in the oil pipe between the three-position four-way electromagnetic directional valve 14 and the ultrahigh pressure hydraulic control one-way valve 30-35 returns to the oil tank through the three-position four-way electromagnetic directional valve 14 and the two-position four-way electromagnetic directional valve 24-29; meanwhile, an electromagnet (12CT) of the electromagnetic on-off valve 48 is electrified, hydraulic oil enters the reciprocating type supercharger 49, ultrahigh-pressure hydraulic oil generated by the operation of the reciprocating type supercharger enters working cavities of six working cylinders through the two-position seven-way valve 17, and the synchronous lifting of the hydraulic oil pressure of the six working cylinders is realized.

Pressure maintaining: when the high-pressure sensor 11 detects that the pressure of the ultrahigh pressure area reaches the set pressure maintaining pressure, the overpressure is over, the large oil pump motor 4 stops working, the electromagnet (10CT) and the electromagnet (12CT) are powered off, and the pressure maintaining step is started; an electromagnet (11CT) of the two-position four-way electromagnetic reversing valve 16 is electrified to keep the communication state of working cavities of the six working cylinders, and the pressure in six directions of the cubic press is equal in the pressure maintaining process.

Pressure relief: and when the pressure maintaining time reaches the set setting, finishing pressure maintaining and starting pressure relief. When the small oil pump 3 is started, the electromagnet (10CT) of the electromagnetic overflow valve 12 is electrified, when the low-pressure sensor 10 detects that the oil pressure of a low-pressure oil line exceeds the lowest oil pressure capable of opening the ultrahigh-pressure hydraulic control on-off valve 52, the electromagnet (13CT) of the two-position four-way electromagnetic directional valve 51 is electrified, hydraulic oil in a main pipeline passes through the two-position four-way electromagnetic directional valve 51, the ultrahigh-pressure liquid air on-off valve 52 is pushed to work, an ultrahigh-pressure relief channel is opened, and ultrahigh-pressure hydraulic oil reaches the stepping unloading valve 54; by being able to open the ultrahigh pressure liquid-air on-off valve 52, the PLC controls the step motor to work, drives the valve core of the step unloading valve to rotate step by step, and directly releases pressure from the ultrahigh pressure region according to the set pressure release parameters. In the pressure relief process, when the actual oil pressure of the ultrahigh pressure area detected by the high-pressure sensor 11 is lower than the pressure relief setting parameter 3MPa, the electromagnet (13CT) is powered off, the ultrahigh pressure liquid air on-off valve 52 is closed in an emergency, and when the pressure relief setting parameter detected by the high-pressure sensor 11 is equal to the actual oil pressure of the ultrahigh pressure area, the electromagnet (13CT) is electrified, the ultrahigh pressure liquid air on-off valve 52 is opened, and pressure relief is continued.

And (3) return stroke: when the high-pressure sensor 11 detects that the oil pressure in the cylinder reaches the set return pressure, the pressure relief is terminated and the return operation is started. The motor 5 of the small oil pump 3 stops working, the motor 4 of the large oil pump 2 is started, the electromagnets (11CT and 13CT) are powered off, the two-position seven-way valve is reset, and the communication of the working cavities of the six working cylinders is disconnected; the ultrahigh pressure hydraulic control on-off valve 52 controls the hydraulic oil in the oil pipe of the oil way to automatically return to the oil tank through the two-position four-way electromagnetic directional valve 51, and the ultrahigh pressure hydraulic control on-off valve returns to the original position. The electromagnet (1CT) of the three-position four-way electromagnetic directional valve 14 is electrified, the electromagnet (9CT) of the two-position four-way electromagnetic directional valve 15 is electrified, and the electromagnet (10CT) of the electromagnetic overflow valve 12 is electrified, so that hydraulic oil in the main pipeline passes through the two-position four-way electromagnetic directional valve 15 and then pushes the ultrahigh-pressure hydraulic control one-way valve 30-35 to work, a hydraulic oil backflow channel in a working cavity of the working cylinder is opened, and the hydraulic oil in the working cavity of the working cylinder returns to a tank from the two-position four-way electromagnetic directional valve 24-29; meanwhile, after passing through the three-position four-way electromagnetic directional valve 14, the hydraulic oil in the main pipeline is reduced to a preset value under the action of the overflow valve 13, and then the hydraulic oil is injected into a return cavity of the working cylinder to push the plungers 42 to 47 to return. Meanwhile, the stepping motor drives the stepping unloading valve 54 to rotate towards the original point until the system detects that the stepping motor reaches the original point, and the stepping motor rotates reversely by a certain angle until the unloading valve returns to the original position.

And finishing one working cycle: when the return time reaches the set time, the motor 4 of the large oil pump 2 stops working, all the electromagnets are not electrified, the three-position four-way electromagnetic directional valve 14 is positioned in the middle position, and the hydraulic oil in the return cavity of the working cylinder automatically returns to the oil tank through a middle position overflow hole of the three-position four-way electromagnetic directional valve until the pressure of the hydraulic oil in the return cavity returns to zero; the ultrahigh pressure hydraulic control one-way valve controls hydraulic oil in an oil pipe of the oil way to automatically return to the oil tank through the two-position four-way electromagnetic directional valve 15, the ultrahigh pressure hydraulic control one-way valve returns to the original position, and the pressure of the hydraulic oil in the oil pipe returns to zero; the equipment stops working and one synthesis cycle is finished.

In the automatic working state, when the stepping motor starts to operate, the stepping motor drives the valve core of the stepping unloading valve to automatically rotate towards the original point until the system detects that the valve core of the stepping unloading valve reaches the original point, and the valve core of the stepping unloading valve is reversely rotated by a certain angle until the valve core of the stepping unloading valve returns to the original position, and an alarm function that the valve core of the stepping unloading valve does not return to the original position is arranged in the pressure maintaining step.

In the automatic working state, the system detects whether the pressure of the control oil way system is enough to open the ultrahigh pressure liquid-air on-off valve at the initial stage of the pressure relief working step.

The protection function of the ultrahigh pressure liquid-air on-off valve is set in the pressure relief process in the automatic working state when the ultrahigh pressure oil way pressure exceeds the lower limit.

After the pressure relief is finished in the automatic working state, the stepping motor automatically rotates towards the original point direction until the valve core of the stepping unloading valve returns.

The automatic working state is provided with accurate pressure control measures such as automatic pressure compensation under low pressure and automatic pressure relief under high pressure in the pressure maintaining working step.

Pressure supplementing in the pressure maintaining process: in the pressure maintaining process, if the high-pressure sensor 11 detects that the pressure of the ultrahigh pressure area is lower than the set pressure maintaining pressure by 0.3MPa, the small oil pump 3 is started, the electromagnets (10CT, 11CT and 12CT) are electrified to perform pressure compensation on the ultrahigh pressure area until the actual pressure reaches the set pressure maintaining pressure, the motor 5 stops running, the electromagnets (10CT and 12CT) are powered off, and the pressure compensation is finished.

Pressure relief action in the pressure maintaining process: in the pressure maintaining process, if the high-pressure sensor 11 detects that the oil pressure of the ultrahigh pressure area is higher than the set pressure maintaining pressure by more than 0.3MPa, the program automatically enters the pressure maintaining step and automatically releases the pressure when the pressure is too high, the ultrahigh pressure area is released, the motor 5 stops running until the actual pressure reaches the set pressure maintaining pressure, the electromagnets (10CT and 13CT) are powered off, and the pressure supplementing is finished. The stepping motor drives the valve core of the stepping unloading valve 54 to rotate towards the original point until the valve core of the stepping unloading valve returns.

The adjustment of the working state comprises the actions of single-cylinder advancing, pressure relief, return stroke, emergency pressure relief and the like.

Single-cylinder advance: when the single-cylinder forward operation is carried out under the adjustment working state, the motor 4 of the large oil pump 2 is started, the electromagnet (10CT) of the electromagnetic overflow valve is electrified, the electromagnet (2CT) of the three-position four-way electromagnetic directional valve 14 and the electromagnet of the three-position four-way electromagnetic directional valve corresponding to the working cylinder are electrified, and hydraulic oil enters the working cavity of the corresponding working cylinder to push the plunger to move forward.

Pressure relief/return stroke: when the pressure relief/return operation is performed in the adjustment working state, if the high-pressure sensor 11 detects that the oil pressure of the ultrahigh pressure area is higher than the set return pressure, the program executes the pressure relief action until the oil pressure of the ultrahigh pressure area is relieved to the return pressure, and then executes the return action; if the oil pressure of the ultrahigh pressure area is less than or equal to the set return pressure, the program directly executes the return action.

Emergency pressure relief: when special conditions are met, the ultrahigh pressure area of the cubic press needs to be quickly relieved, the motor 5 of the small oil pump 3 is started, the electromagnet (10CT) of the electromagnetic overflow valve 12 is electrified, and the electromagnet (11CT) of the two-position four-way electromagnetic directional valve 16 is electrified, so that the ultrahigh pressure area is ensured to be in a communicated state; an electromagnet (13CT) of the two-position four-way electromagnetic directional valve 51 is electrified, and the PLC controls the stepping motor to rotate at a certain angle quickly to drive a valve core of the stepping unloading valve to open to a certain degree quickly so as to start emergency pressure relief. When the oil pressure of the ultrahigh pressure area is reduced to be lower than the return pressure, the return operation can be carried out, and the return action is switched to.

The pressure relief speed of the emergency pressure relief action for adjusting the working state can be adjusted, the pressure relief speed is adjusted by controlling the stepping motor to rotate forwards or backwards for a certain angle once, and the pressure relief speed can be freely adjusted from a pressure maintaining state to a state that the stepping unloading valve is completely opened.

The invention relates to a hydraulic system of a large-cylinder-diameter cubic press and a control method, wherein the hydraulic system adopts a reciprocating type supercharger to provide ultrahigh-pressure hydraulic oil, thereby greatly reducing the consumption of the hydraulic oil and effectively avoiding the overtravel problem of the traditional supercharger; the direct safe pressure relief of the ultrahigh pressure region is realized by adopting a stepping motor pressure relief module; the control method can accurately control the oil pressure of the hydraulic system and realize long-time stable operation and stable pressure relief of the cubic press.

The present embodiment is not intended to limit the shape, material, structure, etc. of the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.

In the description of the present invention, it is to be understood that the terms "central", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be considered as limiting the scope of the present invention.

If the terms "first," "second," etc. are used herein to define parts, those skilled in the art will recognize that: the use of "first" and "second" is merely for convenience in describing the invention and to simplify the description, and unless otherwise stated the above words are not intended to have a special meaning.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: it is to be understood that modifications may be made to the technical solutions described in the foregoing embodiments, or equivalents may be substituted for some of the technical features thereof, but such modifications or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.