Hydraulic system for stable pressure maintaining of hot pressing sintering aluminum nitride heater

Abstract

The invention discloses a hydraulic system for stable pressure maintaining of a hot-pressed sintered aluminum nitride heater. The hydraulic system comprises a main oil tank and a stamping oil cylinder. The main oil tank is connected with a first main oil way, the first main oil way is respectively connected with an upper cylinder main oil way and a lower cylinder oil way through a first two-position cartridge valve, the upper cylinder main oil way is respectively connected with an inner cylinder oil way and the main oil tank through a second two-position cartridge valve, and an outer cylinder oil way is connected with the inner cylinder oil way through a cartridge valve; the first main oil way, the second main oil way and the third main oil way are connected with a pressure supplementing main oil way together. The inner cylinder oil way and the outer cylinder oil way are each provided with a first hydraulic control one-way valve, the first hydraulic control one-way valves are connected with a first pressure relief oil way connected with the second main oil way, and the inner cylinder oil way and the outer cylinder oil way are connected with a second pressure relief oil way together between the first hydraulic control one-way valves and the stamping oil cylinders. The design of the inner cylinder and the outer cylinder can realize the controllability of the pressure relief range of the stamping oil cylinder, the stability of the pressurization rate is good through a pressure relief oil way, and the pressure fluctuation in the pressure relief process is small.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic systems, in particular to a hydraulic system for stabilizing the pressure of a hot-press sintering aluminum nitride heater. BACKGROUND

[0002] The function of a hydraulic system is to increase the force by changing the pressure, and a complete hydraulic system is composed of five parts, namely power elements, execution elements, control elements, auxiliary elements and hydraulic oil. Hydraulic systems can be divided into two categories: hydraulic transmission systems and hydraulic control systems. The hydraulic transmission system mainly functions to transmit power and motion, while the hydraulic control system requires the hydraulic system output to meet specific performance requirements.

[0003] In the prior art, a hydraulic system for an aluminum nitride heater is disclosed, which includes a main oil tank, a filter, a hydraulic pump, an overflow valve, a cartridge valve, a proportional valve, a first hydraulic control check valve and a punch oil cylinder. The cartridge valve is used to control the oil supply direction, and the proportional valve is used to adjust the oil flow. However, under this structure, the pressure is likely to exceed the limit when pressurizing, and the pressure drops too quickly when depressurizing, which cannot be controlled. The impact on the valve body is large, and the pressure fluctuation is large, which will directly impact the pipeline, joints, sealing elements and other elements, thereby causing metal fatigue, cracks and even pipe bursts, shortening the service life of the elements. At the same time, it will interfere with the response of precision elements such as proportional valves and servo valves, causing the punch oil cylinder to move unstably. Therefore, how to optimize the hydraulic system for the aluminum nitride heater to improve the stability of the pressurization rate and reduce the pressure fluctuation during the depressurization process is an important research direction in the industry.

[0004] Therefore, it is necessary to design a new technical solution to solve the above problems. SUMMARY

[0005] Therefore, it is necessary to design a new technical solution to solve the above problems.

[0006] To achieve the above object, the present application adopts the following technical solutions: A hydraulic system for stabilizing and maintaining pressure of a hot-pressed sintered aluminum nitride heater, comprising a main oil tank and a stamping oil cylinder, the stamping oil cylinder comprising an upper cylinder and a lower cylinder, the upper cylinder comprising an inner cylinder and an outer cylinder located at the outer periphery of the inner cylinder, the inner cylinder and the outer cylinder being respectively connected with an inner cylinder oil path and an outer cylinder oil path; The main oil tank is connected with a first main oil path, the first main oil path is connected with an upper cylinder total oil path and a lower cylinder oil path connected with the lower cylinder through a first two-position cartridge valve, the upper cylinder total oil path is connected with the inner cylinder oil path and the main oil tank through a second two-position cartridge valve, and the outer cylinder oil path is connected with the inner cylinder oil path through a cartridge valve. The upper cylinder total oil path is connected with a control oil path for adjusting oil flux, a pre-electromagnetic valve and a first servo proportional valve are sequentially arranged on the control oil path, and the outlet of the first servo proportional valve is connected with the main oil tank. The main oil tank is also connected with a second main oil path and a third main oil path, a double pump is arranged on the first main oil path and the second main oil path, a first hydraulic pump is arranged on the third main oil path, the first main oil path, the second main oil path and the third main oil path are connected with a pressure compensation main oil path, the pressure compensation main oil path is connected with the lower cylinder oil path and the inner cylinder oil path through a second servo proportional valve, and the pressure compensation main oil path can selectively supply oil to the inner cylinder and the lower cylinder. First hydraulic control check valves are arranged on the inner cylinder oil path and the outer cylinder oil path, the first hydraulic control check valves are connected with a first pressure relief oil path connected with the second main oil path, and a liquid filling valve for controlling the opening and closing of the oil port of the first hydraulic control check valve is arranged on the first pressure relief oil path. The inner cylinder oil path and the outer cylinder oil path are connected with a second pressure relief oil path connected with the main oil tank between the first hydraulic control check valves and the stamping oil cylinder, a P-T throttle valve and a reversing switch valve are arranged on the second pressure relief oil path, and the reversing switch valve is located on the side of the P-T throttle valve close to the main oil tank.

[0007] As a preferred solution, first one-way valves that are unidirectionally conducted towards the stamping oil cylinder are arranged on the first main oil path, the second main oil path and the third main oil path, a second one-way valve that is unidirectionally conducted towards the stamping oil cylinder is arranged between the second main oil path and the third main oil path of the pressure compensation main oil path, and a first electromagnetic valve is arranged between the second one-way valve and the second main oil path of the pressure compensation main oil path.

[0008] As a preferred solution, overflow oil paths connected with the main oil tank are arranged between the first one-way valves of the second main oil path and the third main oil path and the main oil tank, and overflow structures are arranged on the overflow oil paths.

[0009] As a preferred scheme, the second servo proportional valve is connected with the lower cylinder oil path and the inner cylinder oil path through a first pressure compensation oil path and a second pressure compensation oil path respectively, and a second one-way valve which is unidirectionally conducted towards the punch cylinder is arranged on the first pressure compensation oil path and the second pressure compensation oil path, and a two-position two-way reversing valve is arranged on the first pressure compensation oil path at the input end side of the second one-way valve.

[0010] As a preferred scheme, the liquid filling valve is a two-position four-way reversing valve, the second main oil path, the main oil tank and the first hydraulic control one-way valve are connected to the two-position four-way reversing valve, and a reverse one-way valve is further connected to the two-position four-way reversing valve, when the liquid filling valve is opened, the double pump drives the oil to open the first hydraulic control one-way valve, so that the pressure relief of the punch cylinder is realized, and when the liquid filling valve is closed, the first hydraulic control one-way valve is connected with the main oil tank, and the first hydraulic control one-way valve normally works.

[0011] As a preferred scheme, the inner cylinder oil path and the outer cylinder oil path are connected with the second pressure relief oil path through a first branch and a second branch respectively, and a third one-way valve which is unidirectionally conducted towards the main oil tank is arranged on the first branch and the second branch, when the punch cylinder is pressurized, the P-T throttle valve is speed-regulated according to the oil pressure, when the punch cylinder is depressurized, the damping hole of the P-T throttle valve plays a role of pressure buffering, and when the oil pressure is reduced to the required stable pressure, the second pressure relief oil path is closed through the reversing switch valve, so that the pressure in the punch cylinder is kept stable.

[0012] As a preferred scheme, the first main oil path and the lower cylinder oil path are both provided with a pressure reduction structure.

[0013] As a preferred scheme, the upper cylinder total oil path, the inner cylinder oil path and the outer cylinder oil path are all provided with a pressure sensor.

[0014] As a preferred scheme, the main oil tank is further connected with a cooling system, the cooling system comprises a cooling oil path which is closed-loop connected with the main oil tank, and a condenser, a first filter and a second hydraulic pump which are sequentially arranged on the cooling oil path, and the cooling system further comprises an oil temperature sensor for monitoring the oil temperature in the main oil tank.

[0015] As a preferred scheme, the main oil tank is further connected with a liquid supplementing system, and the liquid supplementing system comprises a liquid level meter for monitoring the oil amount in the main oil tank.

[0016] Compared with the prior art, the present application has obvious advantages and beneficial effects, and specifically, the above technical scheme can know that: Mainly, its outer cylinder oil circuit is connected with the inner cylinder oil circuit through the plug-in valve, so that oil can be supplied to the inner cylinder first during the pressurization process, and then supplied to the outer cylinder through the plug-in valve after reaching the preset pressure. The inner and outer cylinders are designed to realize the controllability of the pressure relief range of the stamping oil cylinder. When the pressure needs to be adjusted, only the corresponding liquid filling valve of the inner cylinder is opened to realize small range pressure regulation, and the pressure fluctuation is smaller than that of the corresponding liquid filling valve of the outer cylinder. When the liquid filling valve is opened, the servo proportional valve acts as a pressure reducing valve, and the pressure reducing rate can be controlled through the servo proportional valve. In addition, the second pressure relief oil circuit has the functions of throttling buffering and pressure gradual control, which can prevent pressure shock caused by load mutation, realize independent pressure reduction and automatic pressure stabilization, and the P-T throttle valve and the reversing on-off valve act as a pressure reducing valve with buffering function, so that the stability of the pressurization rate is good and the pressure fluctuation during the pressure relief process is small.

[0017] In order to more clearly illustrate the structural features and effects of the present application, the present application will be described in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The hydraulic system principle diagram of the preferred embodiment of the present application.

[0019] BRIEF DESCRIPTION OF DRAWINGS 10, main oil tank; 101, first main oil circuit; 102, upper cylinder total oil circuit; 103, control oil circuit; 104, second main oil circuit; 105, third main oil circuit; 106, pressure compensation main oil circuit; 107, overflow oil circuit; 108, second pressure relief oil circuit; 20, stamping oil cylinder; 21, upper cylinder; 211, inner cylinder; 212, outer cylinder; 22, lower cylinder; 201, inner cylinder oil circuit; 202, outer cylinder oil circuit; 203, lower cylinder oil circuit; 204, first branch; 205, second branch; 30, first two-position plug-in valve; 40, second two-position plug-in valve; 50, plug-in valve; 60, pre-electromagnetic valve; 70, first servo proportional valve; 80, double pump; 90, first hydraulic pump; 100, second servo proportional valve; 1001, first pressure compensation oil circuit; 1002, second pressure compensation oil circuit; 110, first one-way valve; 120, second one-way valve; 130, first electromagnetic valve; 140, two-stage one-way valve; 150, two-position two-way reversing valve; 160 overflow valve; 170 second electromagnetic valve; 180 second oil filter; 190 first hydraulic control check valve; 1901 first pressure relief oil path; 200 liquid filling valve; 210 reverse check valve; 220 P-T throttle valve; 230 reversing switch valve; 240 third check valve; 250 second hydraulic control check valve; 260 third electromagnetic valve; 270 pressure sensor; 280 cooling system; 2801 cooling oil path; 2802 condenser; 2803 first filter; 2804 second hydraulic pump; 2805 oil temperature sensor; 290 liquid supplement system; 2901 liquid level gauge; 2902 liquid supplement pipeline. DETAILED DESCRIPTION

[0020] First of all, it needs to be pointed out that in the description of the present application, the terms "upper", "lower", "left", "right" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0021] Please refer to Figure 1 The specific structure of the preferred embodiment of the present application is shown, which includes a main oil tank 10 and a punch oil cylinder 20.

[0022] The punch oil cylinder 20 includes an upper cylinder 21 and a lower cylinder 22, the upper cylinder 21 includes an inner cylinder 211 and an outer cylinder 212 located on the outer periphery of the inner cylinder 211, the inner cylinder 211 and the outer cylinder 212 are respectively connected with an inner cylinder oil path 201 and an outer cylinder oil path 202; the main oil tank 10 is connected with a first main oil path 101, the first main oil path 101 is connected with an upper cylinder total oil path 102 and a lower cylinder oil path 203 connected with the lower cylinder 22 through a first two-position cartridge valve 30, the upper cylinder total oil path 102 is connected with the inner cylinder oil path 201 and the main oil tank 10 through a second two-position cartridge valve 40, and the outer cylinder oil path 202 is connected with the inner cylinder oil path 201 through a cartridge valve 50; The first two-position cartridge valve 30, the second two-position cartridge valve 40 and the cartridge valve 50 are all controlled by electromagnetic valves, in the pressurizing process, the upper cylinder 21 is supplied with oil while the lower cylinder 22 is discharged, so that a pressure difference is formed between the upper cylinder 21 and the lower cylinder 22, the punch oil cylinder 20 moves downward, and the product is pressurized; in the pressure releasing process, the lower cylinder 22 is supplied with oil while the upper cylinder 21 is discharged, so that a pressure difference is formed between the upper cylinder 21 and the lower cylinder 22, the punch oil cylinder 20 moves upward, and the product is depressurized.

[0023] The upper cylinder total oil circuit 102 is connected with a control oil circuit 103 for adjusting oil flux, the control oil circuit 103 is sequentially provided with a preposed electromagnetic valve 60 and a first servo proportional valve 70, the outlet of the first servo proportional valve 70 is connected with the main oil tank 10, the preposed electromagnetic valve 60 can control the on-off of the oil circuit, and the first servo proportional valve 70 can adjust the oil flux by changing the relative position of the valve core in the valve body, so as to control the speed of the pressurizing and depressurizing process.

[0024] The main oil tank 10 is also connected with a second main oil circuit 104 and a third main oil circuit 105, the first main oil circuit 101 and the second main oil circuit 104 are provided with a double pump 80, the third main oil circuit 105 is provided with a first hydraulic pump 90, the first main oil circuit 101, the second main oil circuit 104 and the third main oil circuit 105 are connected with a pressure compensation main oil circuit 106, the pressure compensation main oil circuit 106 is connected with the lower cylinder oil circuit 203 and the inner cylinder oil circuit 201 through a second servo proportional valve 100, and the pressure compensation main oil circuit 106 can selectively supply oil to the inner cylinder 211 and the lower cylinder 22; Specifically, the first main oil path 101, the second main oil path 104, and the third main oil path 105 are each provided with a first one-way valve 110 for unidirectional conduction towards the punch oil cylinder 20, the pressure compensation main oil path 106 is provided with a second one-way valve 120 for unidirectional conduction towards the punch oil cylinder 20 between the second main oil path 104 and the third main oil path 105, the pressure compensation main oil path 106 is provided with a first electromagnetic valve 130 between the second one-way valve 120 and the second main oil path 104, the second servo proportional valve 100 is connected to the lower cylinder oil path 203 and the inner cylinder oil path 201 through a first pressure compensation oil path 1001 and a second pressure compensation oil path 1002 respectively, the first pressure compensation oil path 1001 and the second pressure compensation oil path 1002 are each provided with a two-stage one-way valve 140 for unidirectional conduction towards the punch oil cylinder 20, and the first pressure compensation oil path 1001 is provided with a two-position two-way directional valve 150 on the input end side of the two-stage one-way valve 140; wherein the second servo proportional valve 100 can adjust the oil flow of the pressure compensation main oil path 106 as needed, and by controlling the position of the valve core, the pressure compensation main oil path 106 can be opened and closed, the punch oil cylinder 20 can be pressurized when the upper cylinder 21 is supplemented with oil, and the punch oil cylinder 20 can be depressurized when the lower cylinder 22 is supplemented with oil, the two-position two-way directional valve 150 can be used to close the emergency oil path, and the two-stage one-way valve 140 can prevent backflow of oil. Preferably, the first one-way valve 110 of the second main oil path 104 and the third main oil path 105 is provided with an overflow oil path 107 connected to the main oil tank 10 between the main oil tank 10, the overflow oil path 107 is provided with an overflow structure, the overflow structure includes an overflow valve 160 and a second electromagnetic valve 170 for controlling the overflow valve 160, and the second main oil path 104 and the third main oil path 105 are provided with a second oil filter 180 on the input side of the overflow structure.

[0025] The inner cylinder oil path 201 and the outer cylinder oil path 202 are each provided with a first hydraulic control one-way valve 190, the first hydraulic control one-way valve 190 is connected with a first pressure relief oil path 1901 connected to the second main oil path 104, and the first pressure relief oil path 1901 is provided with a liquid filling valve 200 for controlling the opening and closing of the oil port of the first hydraulic control one-way valve 190; Specifically, the liquid filling valve 200 is a two-position four-way directional valve, the second main oil line 104, the main oil tank 10 and the first hydraulic control check valve 190 are connected to the two-position four-way directional valve, and the two-position four-way directional valve is further connected with a reverse check valve 210. When the liquid filling valve 200 is opened, the double pump 80 drives the oil to open the first hydraulic control check valve 190, so as to realize the pressure relief of the stamping oil cylinder 20. When the liquid filling valve 200 is closed, the first hydraulic control check valve 190 is connected with the main oil tank 10, and there is no external pressure at the first hydraulic control check valve 190, so that the first hydraulic control check valve 190 normally works, and the reverse check valve 210 can prevent the oil in the stamping oil cylinder 20 from flowing back. When the liquid filling valve 200 is opened, the first servo proportional valve 70 functions as a pressure reducing valve, and the pressure reducing rate can be controlled by adjusting the position of the valve core. When the liquid filling valve 200 is closed, the inlet thereof is connected with the reverse check valve 210, and the reverse check valve 210 can prevent the oil from flowing back to the oil tank, so as to maintain the pressure inside the oil line, which not only ensures that the first hydraulic control check valve 190 can be quickly opened when the liquid filling valve 200 is opened next time, but also makes the oil line pressure stable, so that the pressure fluctuation which can damage the pump is avoided.

[0026] The inner cylinder oil line 201 and the outer cylinder oil line 202 are connected with the second pressure relief oil line 108 connected with the main oil tank 10 between the first hydraulic control check valve 190 and the stamping oil cylinder 20, the second pressure relief oil line 108 is provided with a P-T throttle valve 220 and a reversing switch valve 230, and the reversing switch valve 230 is located on the side of the P-T throttle valve 220 close to the main oil tank 10. Specifically, the inner cylinder oil line 201 and the outer cylinder oil line 202 are connected with the second pressure relief oil line 108 through the first branch line 204 and the second branch line 205 respectively, and the first branch line 204 and the second branch line 205 are provided with a third check valve 240 which is unidirectionally connected to the main oil tank 10. When the stamping oil cylinder 20 is pressurized, the P-T throttle valve 220 adjusts the speed according to the oil pressure. When the stamping oil cylinder 20 is depressurized, the damping hole of the P-T throttle valve 220 functions as a pressure buffer, and when the oil pressure drops to the required stable pressure, the second pressure relief oil line 108 is closed through the reversing switch valve 230, so as to maintain the pressure stability in the stamping oil cylinder 20. The P-T throttle valve 220 and the reversing switch valve 230 function as a pressure reducing valve with a buffer function, the second pressure relief oil line 108 has the functions of throttling, buffering and pressure gradual control, can prevent pressure shock caused by load mutation, can realize self-depressurization and automatic pressure stabilization, can realize the control of pressurization rate accuracy and slow depressurization to accurately control the pressure maintaining pressure, avoids the damage of hydraulic impact to the pipeline elements, realizes slow depressurization and rapid pressure stabilization, and also plays a role in maintaining the stability of the pressurization rate when pressurizing.

[0027] The first main oil circuit 101 and the lower cylinder oil circuit 203 are provided with pressure relief structures, the pressure relief structure comprises a second hydraulic control check valve 250 and a third electromagnetic valve 260 for controlling the second hydraulic control check valve 250, and the second hydraulic control check valve 250 is automatically opened when the working pressure exceeds the threshold, so that the pressure relief is realized; the upper cylinder total oil circuit 102, the inner cylinder oil circuit 201 and the outer cylinder oil circuit 202 are provided with pressure sensors 270.

[0028] The main oil tank 10 is further connected with a cooling system 280, the cooling system 280 comprises a cooling oil circuit 2801 connected with the main oil tank 10 in a closed loop and a condenser 2802, a first filter 2803 and a second hydraulic pump 2804 arranged in sequence on the cooling oil circuit 2801, and the cooling system 280 further comprises an oil temperature sensor 2805 for monitoring the oil temperature in the main oil tank 10, the oil temperature in the main oil tank 10 is monitored in real time through the oil temperature sensor 2805, when the temperature is too high, the second hydraulic pump 2804 is started, so that the oil returns to the main oil tank 10 through the condenser 2802 and the first filter 2803 in sequence, and the oil is cooled in circulation, and when the oil temperature decreases to a set level, the second hydraulic pump 2804 stops.

[0029] The main oil tank 10 is further connected with a liquid supplementing system 290, the liquid supplementing system 290 comprises a liquid level meter 2901 for monitoring the oil amount in the main oil tank 10, and the liquid level meter 2901 is connected with a liquid supplementing pipeline 2902, the oil amount in the main oil tank 10 is monitored through the liquid level meter 2901, manual liquid supplementing or automatic liquid supplementing is prompted, sufficient oil amount in the main oil tank 10 is maintained, and the hydraulic system is maintained to work normally.

[0030] The design focus of the present application is: The main point is that the outer cylinder oil circuit is connected with the inner cylinder oil circuit through the cartridge valve, so that the oil can be supplied to the inner cylinder first in the pressurizing process, and then the oil is supplied to the outer cylinder through the cartridge valve after reaching the preset pressure, the controllability of the pressure relief range of the stamping cylinder is realized, the first pressure relief oil circuit is arranged, when the pressure needs to be adjusted, only the liquid filling valve corresponding to the inner cylinder is opened to realize small-range pressure regulation, the pressure fluctuation is smaller than that of the liquid filling valve corresponding to the outer cylinder, and the servo proportional valve acts as a pressure relief valve when the liquid filling valve is opened, the pressure relief rate can be controlled through the servo proportional valve, the second pressure relief oil circuit has the functions of throttling buffering and pressure gradual control, can prevent pressure shock caused by load mutation, can realize self-pressure reduction and automatic pressure stabilization, the P-T throttling valve and the reversing on-off valve act as pressure relief valves with buffering function, so that the stability of the pressurizing rate is good, and the pressure fluctuation is small in the pressure relief process.

[0031] The above merely describes preferred embodiments of the present application, and is not intended to limit the technical scope of the present application in any way. Any minor modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application shall still fall within the technical scope of the present application.

Claims

1. A hydraulic system for stabilizing and maintaining pressure in a hot-pressed sintered aluminum nitride heater, comprising a main oil tank and a pressing cylinder, the pressing cylinder comprising an upper cylinder and a lower cylinder, the upper cylinder comprising an inner cylinder and an outer cylinder located on the outer periphery of the inner cylinder, the inner cylinder and the outer cylinder being respectively connected to an inner cylinder oil circuit and an outer cylinder oil circuit; characterized in that: The main oil tank is connected to a first main oil circuit. The first main oil circuit is connected to the upper cylinder main oil circuit and the lower cylinder oil circuit connected to the lower cylinder through a first two-position cartridge valve. The upper cylinder main oil circuit is connected to the inner cylinder oil circuit and the main oil tank through a second two-position cartridge valve. The outer cylinder oil circuit is connected to the inner cylinder oil circuit through a cartridge valve. The upper cylinder main oil circuit is connected to a control oil circuit for adjusting the oil flow. The control oil circuit is sequentially equipped with a front solenoid valve and a first servo proportional valve. The outlet of the first servo proportional valve is connected to the main oil tank. The main oil tank is also connected to a second main oil circuit and a third main oil circuit. A dual pump is installed on the first main oil circuit and the second main oil circuit together. A first hydraulic pump is installed on the third main oil circuit. The first main oil circuit, the second main oil circuit, and the third main oil circuit are connected to a pressure-replenishing main oil circuit. The pressure-replenishing main oil circuit is connected to the lower cylinder oil circuit and the inner cylinder oil circuit respectively through a second servo proportional valve. The pressure-replenishing main oil circuit can selectively replenish oil for the inner cylinder and the lower cylinder. Both the inner cylinder oil circuit and the outer cylinder oil circuit are equipped with a first hydraulic control check valve. The first hydraulic control check valve is connected to a first pressure relief oil circuit connected to the second main oil circuit. The first pressure relief oil circuit is equipped with a filling valve for controlling the opening and closing of the oil port of the first hydraulic control check valve. The inner cylinder oil circuit and the outer cylinder oil circuit are connected together between the first hydraulic control check valve and the stamping cylinder to a second pressure relief oil circuit connected to the main oil tank. The second pressure relief oil circuit is equipped with a PT throttle valve and a reversing switch valve. The reversing switch valve is located on the side of the PT throttle valve closer to the main oil tank.

2. The hydraulic system for stabilizing and maintaining pressure in a hot-pressed sintered aluminum nitride heater according to claim 1, characterized in that: Each of the first main oil circuit, the second main oil circuit, and the third main oil circuit is equipped with a first one-way valve that unidirectionally flows toward the stamping cylinder. The pressure replenishing main oil circuit is equipped with a second one-way valve that unidirectionally flows toward the stamping cylinder between the second main oil circuit and the third main oil circuit. The pressure replenishing main oil circuit is equipped with a first solenoid valve between the second one-way valve and the second main oil circuit.

3. The hydraulic system for stabilizing and maintaining pressure in a hot-pressed sintered aluminum nitride heater according to claim 2, characterized in that: The first check valve of the second main oil circuit and the third main oil circuit are both provided with an overflow oil circuit connected to the main oil tank, and the overflow oil circuit is provided with an overflow structure.

4. The hydraulic system for stabilizing and maintaining pressure in a hot-pressed sintered aluminum nitride heater according to claim 1, characterized in that: The second servo proportional valve is connected to the lower cylinder oil circuit and the inner cylinder oil circuit through the first and second supplementary pressure oil circuits respectively. The first and second supplementary pressure oil circuits are each equipped with a two-stage check valve that unidirectionally flows toward the stamping cylinder. A two-position two-way directional valve is provided on the input side of the two-stage check valve in the first supplementary pressure oil circuit.

5. A hydraulic system for stabilizing and maintaining pressure in a hot-pressed sintered aluminum nitride heater according to claim 1, characterized in that: The filling valve is a two-position four-way directional valve. The second main oil circuit, the main oil tank, and the first hydraulic control check valve are all connected to the two-position four-way directional valve. The two-position four-way directional valve is also connected to a reverse check valve. When the filling valve is open, the dual pump drives the oil to open the first hydraulic control check valve, thereby releasing the pressure of the pressurized oil cylinder. When the filling valve is closed, the first hydraulic control check valve is connected to the main oil tank and operates normally.

6. A hydraulic system for stabilizing and maintaining pressure in a hot-pressed sintered aluminum nitride heater according to claim 1, characterized in that: The inner cylinder oil circuit and the outer cylinder oil circuit are respectively connected to the second pressure relief oil circuit through the first branch and the second branch. The first branch and the second branch are each equipped with a third one-way valve that unidirectionally flows towards the main oil tank. When the stamping cylinder is pressurized, the PT throttle valve adjusts the speed according to the oil pressure. When the stamping cylinder is depressurized, the damping orifice of the PT throttle valve acts as a pressure buffer until the oil pressure drops to the required stabilizing pressure. Then, the second pressure relief oil circuit is closed by the reversing switch valve to maintain the pressure inside the stamping cylinder.

7. A hydraulic system for stabilizing and maintaining pressure in a hot-pressed sintered aluminum nitride heater according to claim 1, characterized in that: Both the first main oil circuit and the lower cylinder oil circuit are equipped with pressure reducing structures.

8. A hydraulic system for stabilizing and maintaining pressure in a hot-pressed sintered aluminum nitride heater according to claim 1, characterized in that: Pressure sensors are installed in the main oil circuit of the upper cylinder, the oil circuit of the inner cylinder, and the oil circuit of the outer cylinder.

9. A hydraulic system for stabilizing and maintaining pressure in a hot-pressed sintered aluminum nitride heater according to claim 1, characterized in that: The main oil tank is also connected to a cooling system, which includes a cooling oil circuit connected in a closed loop to the main oil tank and a condenser, a first filter, and a second hydraulic pump arranged sequentially on the cooling oil circuit. The cooling system also includes an oil temperature sensor for monitoring the oil temperature in the main oil tank.

10. A hydraulic system for stabilizing and maintaining pressure in a hot-pressed sintered aluminum nitride heater according to claim 1, characterized in that: The main oil tank is also connected to a fluid replenishment system, which includes a level gauge for monitoring the amount of oil in the main oil tank.

Images