Hydraulic control system and control method for isostatic press

Abstract

The invention discloses a hydraulic control system and method for an isostatic press. The hydraulic control system comprises an oil cylinder, a first hydraulic control oil way, a second hydraulic control oil way and an electric control system. The first hydraulic control oil way comprises a first electromagnetic reversing valve, a first hydraulic control one-way valve assembly, a first pilot control unit and a first stacked one-way throttle valve assembly. The first pilot control unit is used for controlling a hydraulic control one-way valve of the first hydraulic control one-way valve assembly. The second hydraulic control oil way comprises a second electromagnetic reversing valve, a second hydraulic control one-way valve assembly, a second pilot control unit and a second stacked type one-way throttle valve assembly. The second pilot control unit is used for controlling a hydraulic control one-way valve of the second hydraulic control one-way valve assembly. The electric control system is electrically connected with the first electromagnetic directional valve, the second electromagnetic directional valve, the first pilot control unit and the second pilot control unit. The system has better safety, and the influence of pressure fluctuation of a main oil way on the movement stability can be prevented.

Description

Technical Field

[0001] This invention belongs to the field of isostatic press technology, specifically relating to a hydraulic control system and control method for an isostatic press. Background Technology

[0002] An isostatic press is a molding device that operates under ultra-high pressure. Using oil, water, or gas as the working medium, it applies isotropic ultra-high pressure to all surfaces of an object, resulting in high and uniform density, uniform sintering shrinkage, and ease of machining of the molded workpiece. However, during operation, the frame of the isostatic press needs to move to cover the container and bear axial forces. Furthermore, due to the large size and heavy weight of the frame, high stability in its motion control is required. Existing hydraulic systems are insufficient to meet the reliability and safety requirements of isostatic presses. Summary of the Invention

[0003] The purpose of this invention is to provide a hydraulic control system and control method for an isostatic press to meet the requirements of reliability, stability and safety of the isostatic press.

[0004] This invention is achieved through the following technical solution: The hydraulic control system for an isostatic press includes a hydraulic cylinder, a first hydraulic control circuit, a second hydraulic control circuit, and an electrical control system. The first hydraulic control circuit includes a first solenoid directional valve, a first hydraulically controlled check valve assembly, a first pilot control unit, and a first stacked one-way throttle valve assembly. The first hydraulically controlled check valve assembly includes two hydraulically controlled check valves, and the first stacked one-way throttle valve assembly includes two one-way throttle valve assemblies. The first solenoid directional valve is connected to the two hydraulically controlled check valves of the first hydraulically controlled check valve assembly, the two hydraulically controlled check valves of the first hydraulically controlled check valve assembly are connected to the two one-way throttle valve assemblies of the first stacked one-way throttle valve assembly, and the two one-way throttle valve assemblies of the first stacked one-way throttle valve assembly are connected to the rod chamber and rodless chamber of the cylinder, respectively. The first pilot control unit is used to control the hydraulically controlled check valves of the first hydraulically controlled check valve assembly. The second hydraulic control circuit includes a second solenoid directional valve, a second hydraulically controlled check valve assembly, a second pilot control unit, and a second stacked one-way throttle valve assembly. The second hydraulically controlled check valve assembly includes two hydraulically controlled check valves, and the second stacked one-way throttle valve assembly includes two one-way throttle valve assemblies. The second solenoid directional valve is connected to the two hydraulically controlled check valves of the second hydraulically controlled check valve assembly, the two hydraulically controlled check valves of the second hydraulically controlled check valve assembly are connected to the two one-way throttle valve assemblies of the second stacked one-way throttle valve assembly, and the two one-way throttle valve assemblies of the second stacked one-way throttle valve assembly are connected to the rod-side chamber and rodless chamber of the cylinder, respectively. The second pilot control unit is used to control the hydraulically controlled check valves of the second hydraulically controlled check valve assembly. The electronic control system is electrically connected to the first electromagnetic directional valve, the second electromagnetic directional valve, the first pilot control unit, and the second pilot control unit, respectively, and controls the first electromagnetic directional valve, the second electromagnetic directional valve, the first pilot control unit, and the second pilot control unit.

[0005] In some embodiments of the present invention, the first pilot control unit and the second pilot control unit are respectively connected to the X control port of the hydraulic check valve, and are used to control the unlocking and locking of the hydraulic check valve.

[0006] In some embodiments of the present invention, the first pilot control unit and the second pilot control unit include a first accumulator, a miniature electromagnetic ball valve and a first relief valve, wherein the first accumulator is connected to the miniature electromagnetic ball valve and the miniature electromagnetic ball valve is connected to the X control port of the hydraulic check valve.

[0007] In some embodiments of the present invention, a proximity switch is also included, which is used to detect the moving position of the frame and is electrically connected to the electronic control system.

[0008] In some embodiments of the present invention, two sets of buffer units are provided on the first hydraulic control oil circuit. The two sets of buffer units are respectively used to provide buffering for the return oil circuit on the first hydraulic control oil circuit when the second electromagnetic directional valve is closed.

[0009] In some embodiments of the present invention, the buffer unit is respectively disposed between the hydraulic control check valve and the one-way throttle valve assembly of the first hydraulic control oil circuit. The buffer unit includes an electromagnetic switch valve, a check valve and an accumulator. The electromagnetic switch valve is connected to the electronic control system.

[0010] On the other hand, the present invention also provides a hydraulic control method for an isostatic press, used for controlling the hydraulic control system of an isostatic press, comprising the following steps: The control unit of the first pilot valve and the control unit of the second pilot valve control the corresponding hydraulic check valve to unlock; Energize the first and second solenoid directional valves; When a signal is received from the proximity switch, the second solenoid directional valve is de-energized. Once the frame moves to the set position, the control units of the first and second pilot valves control the corresponding hydraulic check valves to lock.

[0011] In some embodiments of the present invention, when the electronic control system receives a signal from the proximity switch, it controls the second electromagnetic reversing valve to close while simultaneously controlling the electromagnetic switching valve corresponding to the buffer unit to open.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention employs two sets of hydraulic control circuits to control the frame, and uses a first pilot valve control unit and a second pilot valve control unit to control the hydraulic check valve. This allows the control of the hydraulic check valve to be unaffected by the oil pressure of the first and second hydraulic control circuits, resulting in better safety. Furthermore, the unlocking pressure can be precisely set according to the first relief valve, preventing the impact of main oil circuit pressure fluctuations on motion stability. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the hydraulic circuit of the isostatic press hydraulic control system according to an embodiment of the present invention.

[0015] Figure 2 This is a schematic diagram of the hydraulic circuit of another embodiment of the hydraulic control system for an isostatic press according to the present invention.

[0016] in: 10. Hydraulic cylinder; 11. Stacked relief valve; 21. First electromagnetic directional valve; 22. First stacked one-way throttle valve assembly; 23. First hydraulically controlled one-way valve assembly. 31. Second electromagnetic directional valve; 32. Second stacked one-way throttle valve assembly; 33. Second hydraulically controlled one-way valve assembly. 41. First pilot valve control unit; 42. Second pilot control unit; 401. First accumulator; 402. Miniature solenoid ball valve; 403. First relief valve; 50. Proximity switch; 60. Buffer unit; 61. Electromagnetic switch valve; 62. Check valve; 63. Second accumulator. 70. Pressure sensor. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0018] Reference Figure 1 In some embodiments of the present invention, the hydraulic control system for the isostatic press is used for motion control of the isostatic press frame, including a hydraulic cylinder 10, a first hydraulic control circuit, a second hydraulic control circuit, and an electrical control system.

[0019] The first hydraulic control circuit includes a first solenoid directional valve 21, a first hydraulically controlled check valve assembly 23, a first pilot control unit 41, and a first stacked one-way throttle valve assembly 22. The first hydraulically controlled check valve assembly 23 includes two hydraulically controlled check valves, and the first stacked one-way throttle valve assembly 22 includes two one-way throttle valve assemblies. The first solenoid directional valve 21 is connected to the two hydraulically controlled check valves of the first hydraulically controlled check valve assembly 23, the two hydraulically controlled check valves of the first hydraulically controlled check valve assembly 23 are connected to the two one-way throttle valve assemblies of the first stacked one-way throttle valve assembly 22, and the two one-way throttle valve assemblies of the first stacked one-way throttle valve assembly 22 are connected to the rod-side chamber and the rodless chamber of the cylinder 10, forming the first hydraulic control circuit.

[0020] The first pilot control unit 41 is used to control the hydraulic check valve of the first hydraulic check valve assembly. The first pilot control unit 41 is connected to the X control port of the hydraulic check valve and controls the unlocking and locking of the hydraulic check valve.

[0021] The second hydraulic control circuit includes a second solenoid directional valve 31, a second hydraulically controlled check valve assembly 33, a second pilot control unit 42, and a second superimposed one-way throttle valve assembly 32. The second hydraulically controlled check valve assembly 33 includes two hydraulically controlled check valves, and the second superimposed one-way throttle valve assembly 32 includes two one-way throttle valve assemblies. The second solenoid directional valve 31 is connected to the two hydraulically controlled check valves of the second hydraulically controlled check valve assembly 33, the two hydraulically controlled check valves of the second hydraulically controlled check valve assembly 33 are connected to the two one-way throttle valve assemblies of the second superimposed one-way throttle valve assembly 32, and the two one-way throttle valve assemblies of the second superimposed one-way throttle valve assembly 32 are connected to the rod-side chamber and rodless chamber of the cylinder 10, forming the second hydraulic control circuit.

[0022] The second pilot control unit 42 adopts the same structure as the first pilot control unit 41 and is used to control the hydraulic check valve in the second hydraulic check valve assembly.

[0023] Reference Figure 1The first pilot valve control unit 41 and the second pilot valve control unit 42 include a first accumulator 401, a miniature electromagnetic ball valve 402 and a first relief valve 403. The first accumulator 401 is connected to the miniature electromagnetic ball valve 402, and the miniature electromagnetic ball valve 402 is connected to the X control port of the hydraulic check valve.

[0024] When the electronic control system de-energizes the miniature electromagnetic ball valve, the miniature electromagnetic ball valve closes, and the oil at the X control port flows back to the T port through the first relief valve, locking the hydraulic check valve. When the electronic control system energizes the miniature electromagnetic ball valve, the miniature electromagnetic ball valve opens, and the first accumulator instantly supplies oil to the X control port. The pressure is maintained at the set value by the first relief valve, unlocking the hydraulic check valve, thereby realizing the control of the hydraulic check valve.

[0025] By using a first pilot valve control unit and a second pilot valve control unit to control the hydraulic check valve, the control of the hydraulic check valve can be made unaffected by the oil pressure of the first hydraulic control oil circuit and the second hydraulic control oil circuit, which has better safety. In addition, the unlocking pressure can be precisely set according to the first relief valve, which can prevent the main oil circuit pressure fluctuation from affecting the stability of movement.

[0026] When controlling the frame movement, the control unit of the first pilot valve control unit and the control unit of the second pilot valve control unit control the corresponding hydraulic check valve to unlock; When the first solenoid directional valve is energized to the left, hydraulic oil flows out from port P and enters the rodless chamber of the cylinder through the first hydraulic control oil circuit, pushing the frame to move forward.

[0027] When the frame needs to be moved out, the first solenoid directional valve is energized to the right, and hydraulic oil enters the rod chamber of the cylinder, pushing the frame to move out.

[0028] During this process, the hydraulic oil control check valve of the first hydraulic control circuit opens, opening the return oil circuit, and the hydraulic oil flows back from the T port to the oil tank.

[0029] When it is necessary to control the frame to move forward quickly, the two sets of solenoid directional valves are simultaneously energized to the left position. Hydraulic oil enters the rodless chamber of the cylinder through the first hydraulic control oil circuit and the second control hydraulic oil circuit, pushing the frame to move forward quickly.

[0030] Similarly, by controlling the right-hand energization of the two sets of solenoid directional valves, hydraulic oil simultaneously enters the rod chamber of the cylinder through the first hydraulic control oil circuit and the second control hydraulic oil circuit, pushing the frame to move out quickly.

[0031] Once the movement is complete, the first and second solenoid directional valves return to the neutral position, the main oil circuit is closed, the control units of the first and second pilot valves are de-energized, the hydraulic check valve control chamber is depressurized, and the frame is rigidly locked.

[0032] The hydraulic control check valve can effectively seal the oil in the two chambers of the cylinder, forming a two-way hydraulic lock to prevent the frame from suddenly moving out when the isostatic pressure equipment is working.

[0033] The superimposed one-way throttle valve assembly is used to regulate the flow rate by adjusting the opening of the one-way throttle valve, thereby achieving the regulation and control of the frame movement speed.

[0034] In some embodiments, a proximity switch 50 is used to detect the moving position of the rack, thereby enabling automatic switching control of the number of opening and closing of the two sets of electromagnetic directional valves, and realizing automated control of the rack moving in and out at fast and slow speeds during the control process.

[0035] When the frame moves forward, the two sets of solenoid directional valves are energized to the left, and hydraulic oil enters the rodless chamber of the cylinder through the first hydraulic control circuit and the second control hydraulic circuit, pushing the frame to move forward quickly. When the frame moves to the proximity switch position, the second solenoid directional valve is closed by the electronic control system, and the frame moves slowly into place.

[0036] After the working cylinder is depressurized, the two sets of solenoid directional valves are energized to the right position by the electronic control system. Hydraulic oil enters the rod chamber of the cylinder through the first hydraulic control oil circuit and the second control hydraulic oil circuit, pushing the frame to move out quickly. At this time, the hydraulic oil control check valve of the oil circuit opens, opening the return oil circuit, and the hydraulic oil in the rodless chamber of the cylinder returns to the oil tank from the T port. When the frame moves out to the proximity switch position, the second solenoid directional valve is closed by the electronic control system, controlling the frame to slowly move out into place.

[0037] A superimposed relief valve 11 is installed in the hydraulic system. By setting the opening pressure, excessive oil pressure is prevented and the safety of the hydraulic system oil circuit is protected.

[0038] In some embodiments, such as Figure 2 Two sets of buffer units 60 are provided in the first hydraulic control oil circuit. The two sets of buffer units 60 are used to provide buffer for the return oil circuit in the first hydraulic control oil circuit when the second solenoid directional valve is closed.

[0039] Two buffer units are respectively installed between the hydraulically controlled check valve and the one-way throttle valve assembly in the first hydraulic control circuit. Each buffer unit includes a solenoid valve 61, a check valve 62, and a second accumulator 63. A safety relief valve is connected to the second accumulator 63. The solenoid valve 61 is connected to the electronic control system. When the electronic control system receives a signal from the proximity switch, it controls the corresponding solenoid valve to open while simultaneously closing the second solenoid directional valve, thus providing buffering.

[0040] Two sets of pressure sensors 70 are installed in the first hydraulic control oil circuit to detect the pressure of the first hydraulic control oil circuit. The two sets of pressure sensors 70 are respectively connected to the electronic control system. When the electronic control system receives the signal of the proximity switch, it controls the electromagnetic switch valve of the buffer unit of the circuit to open when the pressure data of the two sets of pressure sensors suddenly increases.

[0041] On the other hand, in some embodiments of the present invention, an isostatic press hydraulic control method is provided for controlling the hydraulic control system of an isostatic press, comprising the following steps: The control unit of the first pilot valve and the control unit of the second pilot valve control the corresponding hydraulic check valve to unlock; Energize the first and second solenoid directional valves; When a signal is received from the proximity switch, the second solenoid directional valve is de-energized. Once the frame moves to the set position, the control units of the first and second pilot valves control the corresponding hydraulic check valves to lock.

[0042] When the electronic control system receives a signal from the proximity switch, it controls the second electromagnetic reversing valve to close while simultaneously controlling the corresponding electromagnetic switch valve of the buffer unit to open.

[0043] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., used to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of this invention is usually placed in during use. They are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0044] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this invention does not imply that the components are required to be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0045] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A hydraulic control system for an isostatic press, characterized in that, The hydraulic cylinder, the first hydraulic control oil path, the second hydraulic control oil path and the electric control system are included. The first hydraulic control oil path includes a first electromagnetic reversing valve, a first hydraulic control check valve assembly, a first pilot control unit and a first superimposed check valve assembly; the first hydraulic control check valve assembly includes two hydraulic control check valves, and the first superimposed check valve assembly includes two check valve assemblies; the first electromagnetic reversing valve is connected with the two hydraulic control check valves of the first hydraulic control check valve assembly respectively, the two hydraulic control check valves of the first hydraulic control check valve assembly are connected with the two check valve assemblies of the first superimposed check valve assembly respectively, the two check valve assemblies of the first superimposed check valve assembly are connected with the rod cavity and the rodless cavity of the hydraulic cylinder respectively, and the first pilot control unit is used for controlling the hydraulic control check valves of the first hydraulic control check valve assembly. The second hydraulic control oil path includes a second electromagnetic reversing valve, a second hydraulic control check valve assembly, a second pilot control unit and a second superimposed check valve assembly; the second hydraulic control check valve assembly includes two hydraulic control check valves, and the second superimposed check valve assembly includes two check valve assemblies; the second electromagnetic reversing valve is connected with the two hydraulic control check valves of the second hydraulic control check valve assembly respectively, the two hydraulic control check valves of the second hydraulic control check valve assembly are connected with the two check valve assemblies of the second superimposed check valve assembly respectively, the two check valve assemblies of the second superimposed check valve assembly are connected with the rod cavity and the rodless cavity of the hydraulic cylinder respectively, and the second pilot control unit is used for controlling the hydraulic control check valves of the second hydraulic control check valve assembly. The electric control system is electrically connected with the first electromagnetic reversing valve, the second electromagnetic reversing valve, the first pilot control unit and the second pilot control unit respectively, and controls the first electromagnetic reversing valve, the second electromagnetic reversing valve, the first pilot control unit and the second pilot control unit.

2. The isostatic press hydraulic control system of claim 1, wherein, The first pilot control unit and the second pilot control unit are connected with the X control ports of the hydraulic control check valves respectively, and are used for controlling the unlocking and locking of the hydraulic control check valves.

3. The isostatic press hydraulic control system of claim 2, wherein, The first pilot control unit and the second pilot control unit include a first accumulator, a micro electromagnetic ball valve and a first overflow valve, the first accumulator is connected with the micro electromagnetic ball valve, and the micro electromagnetic ball valve is connected with the X control ports of the hydraulic control check valves.

4. The isostatic press hydraulic control system of claim 1, wherein, A proximity switch is further included, the proximity switch is used for detecting the moving position of the rack, and the proximity switch is electrically connected with the electric control system.

5. The isostatic press hydraulic control system of claim 1, wherein, Two groups of buffer units are arranged on the first hydraulic control oil path, and the two groups of buffer units are used for providing buffer for the oil return oil path on the first hydraulic control oil path when the second electromagnetic reversing valve is closed.

6. The isostatic press hydraulic control system of claim 5, wherein, The buffer units are arranged between the hydraulic control check valves and the check valve assemblies of the first hydraulic control oil path respectively, and the buffer units include an electromagnetic switch valve, a check valve and an accumulator, and the electromagnetic switch valve is connected with the electric control system.

7. A method of hydraulic control of an isostatic press, characterized in that The control method for the hydraulic control system of the isostatic pressing machine in any one of claims 1-6 includes the following steps: The first pilot valve control unit and the second pilot valve control unit are controlled to unlock the corresponding hydraulic control check valves. The first pilot valve control unit and the second pilot valve control unit are controlled to unlock the corresponding hydraulic control check valves. Controlling the first electromagnetic reversing valve and the second electromagnetic reversing valve to be powered on; Controlling the second electromagnetic reversing valve to be powered off when the signal of the proximity switch is received; Controlling the first pilot valve control unit and the second pilot valve control unit to lock the corresponding hydraulic control check valve when the gantry moves to the set position.

8. The isostatic press hydraulic control method of claim 7, wherein, Controlling the corresponding electromagnetic on-off valve of the buffer unit to be opened while controlling the second electromagnetic reversing valve to be closed when the electric control system receives the signal of the proximity switch.

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