Ultrahigh-pressure hydraulic system for gear press-fitting process and control method

Abstract

The invention discloses an ultrahigh-pressure hydraulic system for a gear press-fitting process and a control method. Comprising a servo motor, an ultrahigh pressure plunger pump, an oil tank, a safety valve, a first electromagnetic stop valve, a proportional overflow valve, a first pressure sensor, a second electromagnetic stop valve, a first throttling damper, a second throttling damper, a third throttling damper, a third electromagnetic stop valve, a fourth electromagnetic stop valve, an electromagnetic pressure retaining valve and a second pressure sensor. By controlling the overflow pressure of the proportional overflow valve, linear pressure loading and pressure relief of the tensioning tool at 0-70 MPa are achieved, on-off of the throttling dampers is controlled, the pump outlet flow is controlled by adjusting the rotating speed of the motor in a matched mode, the pressure difference of the throttling dampers is changed, and linear pressure loading and pressure relief of the tensioning tool at 70-200 MPa are achieved. The device can be used for a 200MPa ultrahigh-pressure hydraulic system, segmented adjustment of loading pressure is achieved, and the pressure increasing or reducing amplitude and slope of tensioning pressure within 0-200MPa can be controlled.

Description

Technical Field

[0001] The present invention relates to the field of ultra-high pressure hydraulic transmission, and particularly relates to an ultra-high pressure hydraulic system and a control method for a gear pressing process. Background Art

[0002] During the gear pressing process, ultra-high pressure hydraulic oil needs to enter the tensioning tooling to expand or relieve the pressure of the tensioning tooling. To ensure the control accuracy during the pressing process, it is necessary to adjust and control the pressurization and pressure relief values of the tensioning tooling and the pressure change time. The pressure of the ultra-high pressure system can be controlled by a proportional relief valve. However, the maximum pressure inside the tensioning tooling can reach 200 MPa, and currently, the maximum adjustable pressure of the proportional relief valve is only 70 MPa. It is difficult to linearly increase or decrease the pressure above 70 MPa. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides an ultra-high pressure hydraulic system and a control method for a gear pressing process, which can linearly adjust the pressurization / decompression within the range of 0 - 200 MPa for the pressure of the tensioning tooling.

[0004] The object of the present invention is achieved by the following technical solutions: An ultra-high pressure hydraulic system for a gear pressing process includes a servo motor, an ultra-high pressure plunger pump, an oil tank, a safety valve, a first electromagnetic shut-off valve, a proportional relief valve, a first pressure sensor, a second electromagnetic shut-off valve, a first throttle damper, a second throttle damper, a third throttle damper, a third electromagnetic shut-off valve, a fourth electromagnetic shut-off valve, an electromagnetic pressure holding valve, and a second pressure sensor; The servo motor drives the ultra-high pressure plunger pump to rotate and discharge hydraulic oil; The inlet of the safety valve is connected to the outlet oil circuit of the ultra-high pressure plunger pump, and the outlet is connected to the oil tank; the inlet of the first electromagnetic shut-off valve is communicated with the outlet oil circuit of the ultra-high pressure plunger pump, and the outlet is connected to the inlet of the proportional relief valve; the outlet of the proportional relief valve is connected to the oil tank; The first pressure sensor is connected to the outlet oil circuit of the ultra-high pressure plunger pump to feedback the pressure of the ultra-high pressure hydraulic system; the inlet of the second electromagnetic shut-off valve is communicated with the outlet oil circuit of the ultra-high pressure plunger pump, and the outlet is connected to the inlet of the first throttle damper; the first throttle damper, the second throttle damper, and the third throttle damper are connected in series in sequence. The inlet and outlet of the third electromagnetic shut-off valve are respectively connected to the inlet and outlet of the second throttle damper, and the inlet and outlet of the fourth electromagnetic shut-off valve are respectively connected to the inlet and outlet of the third throttle damper; the outlets of the fourth electromagnetic shut-off valve and the third throttle damper are both connected to the oil tank; The two oil ports of the electromagnetic pressure holding valve are respectively connected to the outlet oil circuit of the ultra-high pressure plunger pump and the inlet oil port of the tensioning tooling for the gear pressing process; The second pressure sensor is connected to the oil inlet return circuit of the tensioning tooling, and is used to feedback the oil pressure in the tensioning tooling.

[0005] Further, the first electromagnetic cut-off valve is of a normally open structure, and the second electromagnetic cut-off valve, the third electromagnetic cut-off valve, the fourth electromagnetic cut-off valve and the electromagnetic pressure maintaining valve are all of a normally closed structure.

[0006] Further, the ultra-high pressure plunger pump is a radial plunger pump, and the maximum output pressure is greater than 200 Mpa.

[0007] Further, the safety valve is of a manual overflow valve structure.

[0008] Further, the valve core of the electromagnetic pressure maintaining valve is of a cone valve structure, and can lock the high-pressure side pressure in the power-off state.

[0009] Further, the proportional overflow valve is proportionally adjustable within the pressure range of 0 - 70 MPa.

[0010] Further, the first throttle damper, the second throttle damper and the third throttle damper are all fixed orifice dampers.

[0011] Further, the sum of the maximum pressure differences generated by the first throttle damper, the second throttle damper and the third throttle damper is greater than the highest pressure required for the gear pressing process.

[0012] A control method for an ultra-high pressure hydraulic system for a gear pressing process. The pressurization control in the tensioning tooling is divided into three stages of 0 - 70 MPa, 70 - 140 Mpa, and 140 - 200 Mpa, which are specifically as follows: The pressurization control process of 0 - 70 MPa is as follows: control the first electromagnetic cut-off valve and the electromagnetic pressure maintaining valve to be in the on state, and the second electromagnetic cut-off valve, the third electromagnetic cut-off valve, and the fourth electromagnetic cut-off valve to be in the off state; control the servo motor to rotate, drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil passes through the electromagnetic pressure maintaining valve to quickly fill oil into the tensioning tooling; after the oil filling is completed, the tensioning tooling becomes a closed cavity, and the tensioning pressure is consistent with the ultra-high pressure system pressure; adjust the current of the proportional overflow valve to increase, and control the ultra-high pressure system pressure to rise; adjust the slope of the increase in the current of the proportional overflow valve to control the pressure rise curve of the internal oil in the tensioning tooling; The pressurization control process of 70 - 140 Mpa is as follows: control the first electromagnetic shut-off valve and the third electromagnetic shut-off valve to be in the off state, and the second electromagnetic shut-off valve, the fourth electromagnetic shut-off valve, and the electromagnetic pressure-holding valve to be in the on state; control the servo motor to rotate to drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil flows back through the second electromagnetic shut-off valve, the first throttle damper, the second throttle damper, and the fourth electromagnetic shut-off valve; since the oil flows through two throttle dampers to generate a pressure difference, the outlet pressure and the tension pressure of the ultra-high pressure pump are established; control the rotational speed of the servo motor to increase, the oil discharge flow rate of the ultra-high pressure plunger pump increases, the pressure difference generated on the two throttle dampers increases, and the tension pressure increases accordingly; adjust the slope of the increase in the rotational speed of the servo motor to control the pressure rise curve of the internal oil of the tension tooling. The pressurization control process of 140 - 200 Mpa is as follows: control the first electromagnetic shut-off valve, the third electromagnetic shut-off valve, and the fourth electromagnetic shut-off valve to be in the off state, and the second electromagnetic shut-off valve and the electromagnetic pressure-holding valve to be in the on state; control the servo motor to rotate to drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil flows back through the first throttle damper, the second throttle damper, and the third throttle damper; the outlet pressure and the tension pressure of the ultra-high pressure pump are established through the pressure difference generated by the oil flowing through three throttle dampers; control the rotational speed of the servo motor to increase, the oil discharge flow rate of the ultra-high pressure plunger pump increases, the pressure difference generated on the three throttle dampers increases, and the tension pressure increases accordingly; adjust the slope of the increase in the rotational speed of the servo motor to control the pressure rise curve of the internal oil of the tension tooling. During the entire pressurization control process, the tension pressure is precisely controlled through the pressure feedback of the second pressure sensor.

[0013] Furthermore, the decompression control within the tension tooling is divided into three stages of 200 - 140 Mpa, 140 - 70 Mpa, and 70 - 0 MPa, as follows: The decompression control process of 200 - 140 Mpa is as follows: control the first electromagnetic shut-off valve, the third electromagnetic shut-off valve, and the fourth electromagnetic shut-off valve to be in the off state, and the second electromagnetic shut-off valve and the electromagnetic pressure-holding valve to be in the on state; control the servo motor to rotate to drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil flows back through the first throttle damper, the second throttle damper, and the third throttle damper; control the rotational speed of the servo motor to decrease, the oil discharge flow rate of the ultra-high pressure plunger pump decreases, the pressure difference generated on the three throttle dampers decreases, and the tension pressure decreases accordingly; adjust the slope of the decrease in the rotational speed of the servo motor to control the pressure drop curve of the internal oil of the tension tooling. The 140-70 MPa pressure reduction control process is as follows: the first and third electromagnetic stop valves are controlled to remain in the disconnected state, and the second, fourth, and electromagnetic pressure-maintaining valves are controlled to remain in the connected state; the servo motor is controlled to rotate and drive the ultra-high-pressure plunger pump to discharge hydraulic oil, and the oil returns through the first throttle damper, the second throttle damper, and the fourth electromagnetic stop valve; the speed of the servo motor is controlled to decrease, the flow rate of oil discharged by the ultra-high-pressure plunger pump decreases, the pressure difference generated on the two throttle dampers decreases, and the tensioning pressure decreases accordingly; the slope of the servo motor speed decreases is adjusted to control the pressure drop curve of the oil inside the tensioning tooling; The 70-0Mpa pressure reduction control process is as follows: control the first electromagnetic stop valve and the electromagnetic pressure maintaining valve to be in the on state, and the second electromagnetic stop valve, the third electromagnetic stop valve and the fourth electromagnetic stop valve to be in the off state; control the servo motor to drive the ultra-high pressure plunger pump to discharge hydraulic oil; adjust the current of the proportional relief valve to reduce, and control the pressure drop of the ultra-high pressure hydraulic system; adjust the slope of the current reduction of the proportional relief valve to control the pressure drop curve of the oil inside the tightening tooling.

[0014] The beneficial effects of the present invention are as follows: 1. The present invention can be used in 200MPa-level ultra-high-pressure hydraulic systems to achieve segmented adjustment of loading pressure.

[0015] 2. The present invention can control the pressure increase amplitude and pressure increase slope of the tightening pressure in the range of 0-200 MPa.

[0016] 3. The present invention can control the pressure reduction amplitude and pressure reduction curve of the tensioning pressure in the range of 200-0 MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the principle of an ultra-high pressure hydraulic system for a gear press-fitting process according to an embodiment of the present invention.

[0018] Figure 2 This is the oil circuit diagram for controlling the internal pressure of the tensioning tool of the present invention, which is 0-70MPa pressurization / 70-0MPa decompression.

[0019] Figure 3 This is the state switching oil circuit diagram when the tightening pressure of the present invention rises to 70MPa or drops to 140MPa.

[0020] Figure 4 This is the oil circuit diagram for controlling the internal pressure of the tensioning tool of the present invention to be 70-140MPa pressurized / 140-70MPa decompressed.

[0021] Figure 5 This is the oil circuit diagram for switching when the tightening pressure rises to 140 MPa.

[0022] Figure 6 It is the pressurization / decompression control oil circuit diagram of the pressure within the tensioning tooling of the present invention at 140 - 200 MPa pressurization / 200 - 140 MPa decompression.

[0023] Figure 7 It is the oil circuit diagram for the state switching when the tensioning pressure of the present invention drops to 70 MPa.

[0024] In the figure, 1 is a servo motor, 2 is an ultra-high pressure plunger pump, 3 is an oil tank, 4 is a safety valve, 5 is a first electromagnetic cut-off valve, 6 is a proportional relief valve, 7 is a first pressure sensor, 8 is a second electromagnetic cut-off valve, 9 is a first throttle damper, 10 is a second throttle damper, 11 is a third throttle damper, 12 is a third electromagnetic cut-off valve, 13 is a fourth electromagnetic cut-off valve, 14 is an electromagnetic pressure holding valve, 15 is a second pressure sensor, and 16 is a tensioning tooling. Specific Embodiments

[0025] The present invention will be described in detail below according to the attached drawings and preferred embodiments. The objectives and effects of the present invention will become more apparent. It should be understood that the specific embodiments described herein are merely used to explain the present invention and are not used to limit the present invention.

[0026] As Figure 1 shown, the ultra-high pressure hydraulic system for the gear pressing process of this embodiment includes a servo motor 1, an ultra-high pressure plunger pump 2, an oil tank 3, a safety valve 4, a first electromagnetic cut-off valve 5, a proportional relief valve 6, a first pressure sensor 7, a second electromagnetic cut-off valve 8, a first throttle damper 9, a second throttle damper 10, a third throttle damper 11, a third electromagnetic cut-off valve 12, a fourth electromagnetic cut-off valve 13, an electromagnetic pressure holding valve 14, and a second pressure sensor 15.

[0027] The servo motor 1 drives the ultra-high pressure plunger pump 2 to rotate and discharge hydraulic oil. The ultra-high pressure plunger pump 2 is a radial plunger pump with a maximum output pressure greater than 200 MPa. The output flow rate of the ultra-high pressure plunger pump 2 can be controlled by adjusting the rotation speed of the servo motor 1. The ultra-high pressure plunger pump 2 sucks oil from the oil tank 3, and all the return oil in the system returns to the oil tank 3.

[0028] The inlet of the safety valve 4 is connected to the outlet of the ultra-high pressure plunger pump 2. It is a manual relief valve structure with the pressure set to 210 Mpa to limit the maximum pressure of the ultra-high pressure system. The inlet of the first electromagnetic cut-off valve 5 is connected to the outlet oil circuit of the ultra-high pressure plunger pump 2 and is of a normally open structure. The proportional relief valve 6 is proportionally adjustable within the pressure range of 0 - 70 MPa. The inlet of the proportional relief valve 6 is connected to the outlet of the first electromagnetic cut-off valve 5, and the outlet of the proportional relief valve 6 is connected to the oil tank 3.

[0029] The first pressure sensor 7 is connected to the outlet oil circuit of the ultra-high pressure plunger pump 2 to feedback the pressure of the ultra-high pressure system.

[0030] The inlet of the second electromagnetic cut-off valve 8 communicates with the outlet oil circuit of the ultra-high pressure plunger pump 2 and is of a normally closed structure. The first throttle damper 9 is a fixed orifice damper, and its inlet is connected to the outlet of the second electromagnetic cut-off valve 8. The second throttle damper 10 is a fixed orifice damper, and its inlet is connected to the outlet of the first throttle damper 9. The third throttle damper 11 is a fixed orifice damper, and its inlet is connected to the outlet of the second throttle damper 10, and its outlet is connected to the oil tank 3. The inlet and outlet of the third electromagnetic cut-off valve 12 are respectively connected to the inlet and outlet of the second throttle damper 10 and is of a normally closed structure. The inlet and outlet of the fourth electromagnetic cut-off valve 13 are respectively connected to the inlet and outlet of the third throttle damper 11 and is of a normally closed structure.

[0031] The two oil ports of the electromagnetic pressure holding valve 14 are respectively connected to the outlet oil circuit of the ultra-high pressure plunger pump 2 and the inlet oil port of the tensioning tooling 16, and is of a normally closed structure. The valve core is of a cone valve structure and can lock the pressure on the high-pressure side in the power-off state.

[0032] The second pressure sensor 15 is connected to the return oil circuit of the inlet oil port of the tensioning tooling 16 to feedback the oil pressure inside the tensioning tooling.

[0033] The cavity of the tensioning tooling 16 is a closed cavity, and its inlet oil port and outlet oil port are the same oil port.

[0034] When the servo motor 1 rotates at the highest speed, the pressure difference formed by the hydraulic oil discharged by the ultra-high pressure plunger pump 2 passing through a single throttle damper can reach more than 70 MPa. When the servo motor 1 rotates at a low speed, the pressure difference formed by the hydraulic oil discharged by the ultra-high pressure plunger pump 2 passing through a single throttle damper can be controlled within 30 MPa. The number of throttle dampers is not limited to the three given in this embodiment. The product of the number of throttle dampers and the maximum pressure difference P that a single throttle damper can generate should be greater than the maximum pressure required by the gear tooling. max

[0035] The pressure boosting control process of the tensioning tooling within 0 - 200 MPa is as follows: As Figure 2 shown, the pressure boosting control process of the tensioning tooling within 0 - 70 MPa is as follows: The first electromagnetic cut-off valve 5, the second electromagnetic cut-off valve 8, the third electromagnetic cut-off valve 12, and the fourth electromagnetic cut-off valve 13 are all kept in the power-off state, and the electromagnetic pressure holding valve 14 is in the power-on state. The servo motor 1 rotates at a high speed to drive the ultra-high pressure plunger pump 2 to discharge hydraulic oil, and the oil passes through the electromagnetic pressure holding valve 14 to quickly fill the tensioning tooling 16 with oil; after the oil filling is completed, the tensioning tooling 16 becomes a closed cavity, and the tensioning pressure is consistent with the system pressure; by adjusting the increase of the current of the proportional relief valve 6 to control the rise of the ultra-high pressure system pressure, and by adjusting the slope of the current increase, the pressure rise curve of the oil inside the tensioning tooling 16 can be controlled. Through the pressure feedback of the second pressure sensor 15, the tensioning pressure can be accurately controlled. When the pressure feedback of the second pressure sensor 15 reaches 70 MPa, the pressure boosting control is completed.

[0036] As Figure 3 shown, when the tension pressure rises to 70 MPa, the state switches as follows: the electromagnetic pressure-holding valve 14 loses power, the current of the proportional overflow valve 6 is adjusted to 0, the outlet pressure of the ultra-high pressure plunger pump drops to 0 MPa. Due to the pressure-holding effect of the electromagnetic pressure-holding valve 14, the pressure inside the tension tooling 16 remains at 70 MPa. The servo motor 1 decelerates to the lowest speed. After the second electromagnetic cut-off valve 8 and the fourth electromagnetic cut-off valve 13 are powered on, the first electromagnetic cut-off valve 5 is powered on, and the overflow circuit is shut off. The oil at the pump outlet returns through the second electromagnetic cut-off valve 8, the first throttle damper 9, the second throttle damper 10, and the fourth electromagnetic cut-off valve 13. At this time, the flow rate at the pump outlet is small, and the pressure difference generated across the two throttle dampers is not sufficient to raise the pressure of the pump outlet oil circuit to 70 MPa. The speed of the servo motor 1 is controlled to increase. When the pressure feedback from the first pressure sensor 7 reaches 70 MPa, the pressurization switching state is completed.

[0037] As Figure 4 shown, the pressurization control process for the pressure inside the tension tooling from 70 - 140 MPa is as follows: the first electromagnetic cut-off valve 5, the second electromagnetic cut-off valve 8, the fourth electromagnetic cut-off valve 13, and the electromagnetic pressure-holding valve 14 are powered on, and the third electromagnetic cut-off valve 12 remains powered off. The oil at the pump outlet returns through the second electromagnetic cut-off valve 8, the first throttle damper 9, the second throttle damper 10, and the fourth electromagnetic cut-off valve 13. The speed of the servo motor 1 is controlled to increase, and the oil discharge flow rate of the ultra-high pressure plunger pump 2 increases. The pressure difference generated across the two throttle dampers 9 and 10 increases, and the tension pressure rises accordingly. By adjusting the slope of the rising speed, the pressure rising curve of the oil inside the tension tooling 16 can be controlled. The tension pressure can be precisely controlled through the pressure feedback of the second pressure sensor 15. When the pressure feedback of the second pressure sensor 15 reaches 140 MPa, the pressurization control is completed.

[0038] As Figure 5 shown, when the tension pressure rises to 140 MPa, the state switches as follows: the electromagnetic pressure-holding valve 14 loses power, the servo motor 1 decelerates to the lowest speed, the outlet pressure of the ultra-high pressure plunger pump is lower than 140 MPa. Due to the pressure-holding effect of the electromagnetic pressure-holding valve 14, the pressure inside the tension tooling 16 remains at 140 MPa. The second electromagnetic cut-off valve 8 is powered on, the third electromagnetic cut-off valve 12 and the fourth electromagnetic cut-off valve 13 lose power, and the oil at the pump outlet returns through the second electromagnetic cut-off valve 8, the first throttle damper 9, the second throttle damper 10, and the third throttle damper 11. At this time, the flow rate at the pump outlet is small, and the pressure difference generated across the three throttle dampers is not sufficient to raise the pressure of the pump outlet oil circuit to 140 MPa. The speed of the servo motor 1 is controlled to increase. When the pressure feedback from the first pressure sensor 7 reaches 140 MPa, the pressurization switching state is completed.

[0039] As Figure 6As shown in the figure, the pressurization control process of the tensioning tooling with the internal pressure of 140 - 200 MPa is as follows: The first electromagnetic shut-off valve 5, the second electromagnetic shut-off valve 8, and the electromagnetic pressure-holding valve 14 are energized, and the third electromagnetic shut-off valve 12 and the fourth electromagnetic shut-off valve 13 remain de-energized. The oil at the pump outlet returns through the second electromagnetic shut-off valve 8, the first throttle damper 9, the second throttle damper 10, and the third throttle damper 11, controlling the speed of the servo motor 1 to increase. The oil flow discharged by the ultra-high pressure plunger pump 2 increases, the pressure difference generated on the three throttle dampers increases, and the tensioning pressure rises accordingly. By adjusting the slope of the speed increase, the pressure rise curve of the oil inside the tensioning tooling 16 can be controlled, and the tensioning pressure can be accurately controlled through the pressure feedback of the second pressure sensor 15. When the pressure feedback of the second pressure sensor 15 reaches 200 MPa, the pressurization control is completed.

[0040] The pressurization control process of the tensioning tooling with the internal pressure of 200 - 0 MPa is as follows: As Figure 6 shown in the figure, the depressurization control process of the tensioning tooling with the internal pressure of 200 - 140 MPa is as follows: The first electromagnetic shut-off valve 5, the second electromagnetic shut-off valve 8, and the electromagnetic pressure-holding valve 14 are energized, and the third electromagnetic shut-off valve 12 and the fourth electromagnetic shut-off valve 13 remain de-energized. Control the speed of the servo motor 1 to decrease. The oil flow discharged by the ultra-high pressure plunger pump 2 decreases, the pressure difference generated on the three throttle dampers decreases, and the tensioning pressure decreases accordingly. By adjusting the slope of the speed decrease, the pressure decrease curve of the oil inside the tensioning tooling 16 can be controlled. When the pressure feedback of the second pressure sensor 15 drops to 140 MPa, the depressurization control is completed.

[0041] As Figure 3 shown in the figure, when the tensioning pressure drops to 140 MPa, the state switches as follows: The electromagnetic pressure-holding valve 14 and the third electromagnetic shut-off valve 12 are de-energized, the second electromagnetic shut-off valve 8 and the fourth electromagnetic shut-off valve 13 are energized. The oil at the pump outlet returns through the second electromagnetic shut-off valve 8, the first throttle damper 9, the second throttle damper 10, and the fourth electromagnetic shut-off valve 13. The pressure at the ultra-high pressure plunger pump outlet drops below 140 MPa. Due to the pressure-holding effect of the electromagnetic pressure-holding valve 14, the pressure inside the tensioning tooling 16 remains at 140 MPa. Control the speed of the servo motor 1 to increase. When the pressure feedback of the first pressure sensor 7 reaches 140 MPa, the depressurization switching state is completed.

[0042] As Figure 4As shown in the figure, the pressure reduction control process of the tensioning tooling with the internal pressure of 140 - 70 MPa is as follows: The second electromagnetic shut-off valve 8, the fourth electromagnetic shut-off valve 13, and the electromagnetic pressure-holding valve 14 are energized, and the third electromagnetic shut-off valve 12 remains de-energized. The oil fluid at the pump outlet returns to the oil tank through the second electromagnetic shut-off valve 8, the first throttle damper 9, the second throttle damper 10, and the fourth electromagnetic shut-off valve 13, controlling the rotational speed of the servo motor 1 to decrease. The oil fluid discharged by the ultra-high pressure plunger pump 2 decreases, the pressure difference generated on the two throttle dampers decreases, and the tensioning pressure decreases accordingly. By adjusting the slope of the rotational speed decrease, the pressure drop curve of the oil fluid inside the tensioning tooling 16 can be controlled. When the pressure feedback of the second pressure sensor 15 drops to 70 MPa, the pressure reduction control is completed.

[0043] As Figure 7 shown in the figure, when the tensioning pressure drops to 70 MPa, the state switch is as follows: The electromagnetic pressure-holding valve 14, the second electromagnetic shut-off valve 8, the third electromagnetic shut-off valve 12, and the fourth electromagnetic shut-off valve 13 are de-energized, and the first electromagnetic shut-off valve 5 is energized. The oil fluid at the pump outlet returns to the oil tank through the first electromagnetic shut-off valve 8 and the proportional overflow valve 6. The outlet pressure of the ultra-high pressure plunger pump drops to 0 MPa. Due to the pressure-holding effect of the electromagnetic pressure-holding valve 14, the pressure inside the tensioning tooling 16 remains at 70 MPa. By increasing the current of the proportional overflow valve 6, when the pressure feedback of the first pressure sensor 7 reaches 70 MPa, the pressure reduction switching state is completed.

[0044] As Figure 2 shown in the figure, the pressure reduction control process of the tensioning tooling with the internal pressure of 70 - 0 MPa is as follows: The first electromagnetic shut-off valve 5, the second electromagnetic shut-off valve 8, the third electromagnetic shut-off valve 12, and the fourth electromagnetic shut-off valve 13 all remain de-energized, and the electromagnetic pressure-holding valve 14 is in the energized state. By adjusting the current of the proportional overflow valve 6 to decrease to control the system pressure drop, and adjusting the slope of the current decrease can control the pressure drop curve of the oil fluid inside the tensioning tooling 16. When the pressure feedback of the second pressure sensor 15 drops to 0 MPa, the pressure reduction control is completed.

[0045] Those of ordinary skill in the art can understand that the above are only preferred examples of the invention and are not used to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, for those skilled in the art, they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, etc. made within the spirit and principle of the invention shall be included within the protection scope of the invention.

Claims

1. An ultra-high pressure hydraulic system for a gear press-fitting process, characterized in that, It includes a servo motor, an ultra-high pressure plunger pump, an oil tank, a safety valve, a first electromagnetic shut-off valve, a proportional relief valve, a first pressure sensor, a second electromagnetic shut-off valve, a first throttle damper, a second throttle damper, a third throttle damper, a third electromagnetic shut-off valve, a fourth electromagnetic shut-off valve, an electromagnetic pressure holding valve and a second pressure sensor; The servo motor drives the ultra-high pressure plunger pump to rotate and discharge hydraulic oil; The inlet of the safety valve is communicated with the outlet oil circuit of the ultra-high pressure plunger pump, and the outlet is connected to the oil tank; the inlet of the first electromagnetic shut-off valve is communicated with the outlet oil circuit of the ultra-high pressure plunger pump, and the outlet is connected to the inlet of the proportional relief valve; the outlet of the proportional relief valve is connected to the oil tank; The first pressure sensor is connected to the outlet oil circuit of the ultra-high pressure plunger pump to feedback the pressure of the ultra-high pressure hydraulic system; the inlet of the second electromagnetic shut-off valve is communicated with the outlet oil circuit of the ultra-high pressure plunger pump, and the outlet is connected to the inlet of the first throttle damper; the first throttle damper, the second throttle damper and the third throttle damper are connected in series in sequence, the inlet and outlet of the third electromagnetic shut-off valve are respectively connected to the inlet and outlet of the second throttle damper, and the inlet and outlet of the fourth electromagnetic shut-off valve are respectively connected to the inlet and outlet of the third throttle damper; the outlet of the fourth electromagnetic shut-off valve and the outlet of the third throttle damper are both connected to the oil tank; The two oil ports of the electromagnetic pressure holding valve are respectively connected to the outlet oil circuit of the ultra-high pressure plunger pump and the inlet of the tensioning tooling of the gear pressing process; The second pressure sensor is connected to the return oil circuit of the inlet of the tensioning tooling to feedback the oil pressure in the tensioning tooling.

2. The ultra-high pressure hydraulic system for the gear pressing process according to claim 1, characterized in that, The first electromagnetic shut-off valve is of a normally open structure, and the second electromagnetic shut-off valve, the third electromagnetic shut-off valve, the fourth electromagnetic shut-off valve and the electromagnetic pressure holding valve are all of a normally closed structure.

3. The ultra-high pressure hydraulic system for the gear press-fitting process according to claim 1, characterized in that, The ultra-high pressure plunger pump is a radial plunger pump, and the highest output pressure is greater than 200 Mpa.

4. The ultra-high pressure hydraulic system for the gear pressing process according to claim 1, characterized in that, The safety valve is of a manual relief valve structure.

5. The ultra-high pressure hydraulic system for the gear pressing process according to claim 1, characterized in that, The valve core of the electromagnetic pressure holding valve is of a cone valve structure and can lock the high-pressure side pressure in the power-off state.

6. The ultra-high pressure hydraulic system for the gear press-fitting process according to claim 1, characterized in that, The proportional relief valve is proportionally adjustable within the pressure range of 0-70 MPa.

7. The ultra-high pressure hydraulic system for the gear pressing process according to claim 1, characterized in that, The first throttle damper, the second throttle damper and the third throttle damper are all fixed orifice dampers.

8. The ultra-high pressure hydraulic system for the gear press-fitting process according to claim 7, characterized in that, The sum of the maximum pressure differences generated by the first throttle damper, the second throttle damper and the third throttle damper is greater than the highest pressure required by the gear pressing process.

9. A control method for an ultra-high pressure hydraulic system used in the gear press-fitting process as described in claim 1, characterized in that, The pressurization control in the tensioning tooling is divided into three stages of 0-70 MPa, 70-140 Mpa and 140-200 Mpa, which are specifically as follows: The pressure boosting control process for 0 - 70 MPa is as follows: Control the first electromagnetic shut-off valve and the electromagnetic pressure-holding valve to be in the on state, and the second electromagnetic shut-off valve, the third electromagnetic shut-off valve, and the fourth electromagnetic shut-off valve to be in the off state; Control the servo motor to rotate, driving the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil flows rapidly into the tensioning tool through the electromagnetic pressure-holding valve; After the oil filling is completed, the tensioning tool becomes a closed cavity, and the tensioning pressure is consistent with the ultra-high pressure system pressure; Adjust the current of the proportional relief valve to increase, controlling the rise of the ultra-high pressure system pressure; Adjust the slope of the increase in the current of the proportional relief valve to control the pressure rise curve of the internal oil in the tensioning tool. The pressure boosting control process for 70 - 140 Mpa is as follows: Control the first electromagnetic shut-off valve and the third electromagnetic shut-off valve to be in the off state, and the second electromagnetic shut-off valve, the fourth electromagnetic shut-off valve, and the electromagnetic pressure-holding valve to be in the on state; Control the servo motor to rotate to drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil returns through the second electromagnetic shut-off valve, the first throttle damper, the second throttle damper, and the fourth electromagnetic shut-off valve; Since the oil flows through two throttle dampers to generate a pressure difference, the outlet pressure of the ultra-high pressure pump and the tensioning pressure are established; Control the speed of the servo motor to increase, the discharged oil flow of the ultra-high pressure plunger pump increases, the pressure difference generated on the two throttle dampers increases, and the tensioning pressure rises accordingly; Adjust the slope of the increase in the speed of the servo motor to control the pressure rise curve of the internal oil in the tensioning tool. The pressure boosting control process for 140 - 200 Mpa is as follows: Control the first electromagnetic shut-off valve, the third electromagnetic shut-off valve, and the fourth electromagnetic shut-off valve to be in the off state, and the second electromagnetic shut-off valve and the electromagnetic pressure-holding valve to be in the on state; Control the servo motor to rotate to drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil returns through the first throttle damper, the second throttle damper, and the third throttle damper. The outlet pressure of the ultra-high pressure pump and the tensioning pressure are established by the pressure difference generated when the oil flows through three throttle dampers; Control the speed of the servo motor to increase, the discharged oil flow of the ultra-high pressure plunger pump increases, the pressure difference generated on the three throttle dampers increases, and the tensioning pressure rises accordingly; Adjust the slope of the increase in the speed of the servo motor to control the pressure rise curve of the internal oil in the tensioning tool. During the entire pressure boosting control process, the tensioning pressure is precisely controlled through the pressure feedback of the second pressure sensor.

10. The control method of the ultra-high pressure hydraulic system for the gear pressing process according to claim 9, characterized in that, The pressure reduction control in the tensioning tool is divided into three stages of 200 - 140 Mpa, 140 - 70 Mpa, and 70 - 0 MPa, which are specifically as follows: The pressure reducing control process for 200 - 140 Mpa is as follows: Control the first electromagnetic shut-off valve, the third electromagnetic shut-off valve, and the fourth electromagnetic shut-off valve to be in the off state, and the second electromagnetic shut-off valve and the electromagnetic pressure maintaining valve to be in the on state; Control the servo motor to rotate to drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil flows back through the first throttle damper, the second throttle damper, and the third throttle damper; Control the rotational speed of the servo motor to decrease, the oil discharge flow rate of the ultra-high pressure plunger pump to decrease, the pressure difference generated on the three throttle dampers to decrease, and the tensioning pressure to decrease accordingly; Adjust the slope of the decrease in the rotational speed of the servo motor to control the pressure drop curve of the oil inside the tensioning tooling. The pressure reducing control process for 140 - 70 Mpa is as follows: Control the first electromagnetic shut-off valve and the third electromagnetic shut-off valve to remain in the off state, and the second electromagnetic shut-off valve, the fourth electromagnetic shut-off valve, and the electromagnetic pressure maintaining valve to be in the on state; Control the servo motor to rotate to drive the ultra-high pressure plunger pump to discharge hydraulic oil, and the oil flows back through the first throttle damper, the second throttle damper, and the fourth electromagnetic shut-off valve; Control the rotational speed of the servo motor to decrease, the oil discharge flow rate of the ultra-high pressure plunger pump to decrease, the pressure difference generated on the two throttle dampers to decrease, and the tensioning pressure to decrease accordingly; Adjust the slope of the decrease in the rotational speed of the servo motor to control the pressure drop curve of the oil inside the tensioning tooling. The pressure reducing control process for 70 - 0 Mpa is as follows: Control the first electromagnetic shut-off valve and the electromagnetic pressure maintaining valve to be in the on state, and the second electromagnetic shut-off valve, the third electromagnetic shut-off valve, and the fourth electromagnetic shut-off valve to be in the off state; Control the servo motor to drive the ultra-high pressure plunger pump to discharge hydraulic oil; Adjust the current of the proportional relief valve to decrease to control the pressure drop of the ultra-high pressure hydraulic system; Adjust the slope of the decrease in the current of the proportional relief valve to control the pressure drop curve of the oil inside the tensioning tooling.

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