Hydraulic system of a dual-medium cold isostatic press

Abstract

The utility model relates to cold isostatic press technical field provides a kind of double medium cold isostatic press hydraulic system, including support, pressure-bearing frame and pressure-bearing plate, the outside of support is provided with pressure-bearing frame, the upper and lower end of pressure-bearing frame inside is provided with pressure-bearing plate, the front end of pressure-bearing frame is provided with walking assembly, the utility model adopts the grading pressurization mode of "pre-pressurization (0-8MPa) + booster pressure increasing (maximum 400MPa)" in product pressing quality pressing process, and pressure drops to set lower limit value automatic pressure compensation when pressure maintaining, and 300s pressure maintaining internal pressure drop≤5MPa. Grading pressurization avoids the internal defect (such as blowhole, crack) of product caused by pressure sudden rise, and pressure compensation mechanism ensures that product is formed under stable pressure, improves product density uniformity and mechanical property;Booster uses reciprocating plunger type structure, and overflow oil return and shutdown automatically when overpressure, further guarantee the security of pressurization process.

Description

Technical Field

[0001] This utility model relates to the field of cold isostatic press technology, and in particular to a hydraulic system for a dual-medium cold isostatic press. Background Technology

[0002] Dual-medium cold isostatic presses are widely used in industries such as ceramics and powder metallurgy, and their core performance relies on a stable and reliable hydraulic system. However, some problems still exist with the hydraulic systems of current dual-medium cold isostatic presses on the market:

[0003] In the pressurization control stage, existing hydraulic systems mostly adopt a single-rate continuous pressurization method. When pressing products under high pressure, especially products with high density requirements and complex structures, the sudden pressure increase can easily lead to stress concentration inside the product, resulting in defects such as porosity and microcracks, which seriously affect the density uniformity and mechanical properties of the product. At the same time, although some systems have pressure holding functions, the pressure compensation response is lagging during the pressure holding process, and the pressure fluctuation range is large (often exceeding 5MPa), which cannot provide a stable pressure environment for product molding. In addition, the intensifiers in existing systems mostly adopt traditional piston structures and lack effective overpressure protection mechanisms. Once pressure runaway occurs, it can easily cause equipment overload damage and even safety hazards. Utility Model Content

[0004] The purpose of this invention is to provide a hydraulic system for a dual-medium cold isostatic press, which solves the aforementioned problems when used in operation.

[0005] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a hydraulic system for a dual-medium cold isostatic press, including a support, a pressure-bearing frame, and a pressure-bearing plate. The pressure-bearing frame is provided on the outside of the support, and pressure-bearing plates are provided at the upper and lower ends inside the pressure-bearing frame. A traveling component is provided at the front end of the pressure-bearing frame, and guide rail components are provided on both sides of the bottom of the support. A high-pressure container is provided at the rear end of the pressure-bearing frame, and the high-pressure container is installed at the rear end of the top of the support. An oil tank is provided at the rear end of the support, and an oil pump group is provided at the top of the oil tank. A hydraulic component is provided on the oil tank, and a control pump group is provided on one side of the rear end of the oil tank. A cooling and filtration system is provided on one side of the control pump group.

[0006] Preferably, the hydraulic components include a booster, a control valve assembly, a drive pump assembly, a control pump assembly, a second cooling and filtration system, and a pre-pressurization pump. The booster is located on one side of the oil pump assembly, the control valve assembly is located on one side of the rear end of the booster, a reversing cartridge valve assembly is located on the top of the control valve assembly, the drive pump assembly is located at the rear end of the oil tank, the second cooling and filtration system is located on one side of the oil tank, and the pre-pressurization pump is located on one side of the second cooling and filtration system.

[0007] Preferably, a pressure relief valve assembly is provided at the rear end of the oil pump unit. The pressure relief valve assembly includes a high-pressure valve assembly, a high-pressure proportional pressure relief assembly, a safety pressure relief valve, and pipelines.

[0008] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0009] 1. This utility model provides a dual-medium cold isostatic press hydraulic system that employs a staged pressurization method during the pressing process to improve product quality: "pre-pressurization (0-8MPa) + pressure booster (maximum 400MPa)". During pressure holding, the system automatically replenishes pressure when the pressure drops to a set lower limit, and the pressure drop within 300 seconds is ≤5MPa. Staged pressurization avoids internal defects (such as porosity and cracks) caused by sudden pressure increases. The pressure replenishment mechanism ensures that the product is formed under stable pressure, improving the density uniformity and mechanical properties of the product. The pressure booster adopts a reciprocating plunger structure, automatically overflowing and stopping the machine when overpressure occurs, further ensuring the safety of the pressurization process.

[0010] 2. This utility model provides a hydraulic system for a dual-medium cold isostatic press. Through a pressure relief valve assembly (including a high-pressure proportional pressure relief assembly and a safety pressure relief valve), pressure is released according to set parameters. The time to release pressure from the working pressure to 1.5MPa can be set within 3-60 minutes. It supports segmented pressure release and is fully automatically controlled by a PLC. Proportional pressure release avoids product rebound or equipment impact caused by sudden pressure drops. Segmented pressure release allows for precise adjustment of the pressure release rhythm according to product characteristics. PLC automation control reduces human error, improves the stability and safety of the pressure release process, and simultaneously increases production efficiency.

[0011] 3. This utility model provides a dual-medium cold isostatic press hydraulic system. When the pressure is reduced to 2-0 MPa, the residual fluid is extracted through a built-in large-diameter oil extraction valve and oil pump. The extraction continues for a delay until the upper plug opens, ensuring the isolation sleeve returns to its original state for easy reuse. The cooling and filtration system activates cooling when the oil temperature is ≥45℃ and heating when it is ≤5℃ (stopping at ≤40℃ and ≥15℃ respectively), and circulates and filters the oil through a 10-micron combined filter. Oil extraction and reset ensure rapid equipment recovery, the cooling and heating system maintains the optimal operating temperature of the oil, and the filtration function reduces oil impurities, extends the service life of hydraulic components, and ensures long-term stable operation of the equipment. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0013] Figure 2 This is a partial structural diagram of the present invention. Figure 1 ;

[0014] Figure 3 This is a partial structural diagram of the present invention. Figure 2.

[0015] The following are the annotations in the figure: 1. Support; 2. Pressure-bearing frame; 3. Pressure plate; 4. Traveling assembly; 5. Guide rail assembly; 6. High-pressure vessel; 7. Oil tank; 8. Intensifier; 9. Oil pump assembly; 10. Pressure relief valve assembly; 11. Control valve assembly; 111. Reversing cartridge valve assembly; 12. Drive pump assembly; 13. Control pump assembly; 131. Cooling and filtration system one; 14. Cooling and filtration system two; 15. Pre-pressurization pump. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings.

[0018] Combination Figures 1 to 3 As shown, the hydraulic system of a dual-medium cold isostatic press of this utility model includes a support 1, a pressure-bearing frame 2, and a pressure plate 3. The pressure-bearing frame 2 is provided on the outside of the support 1. The pressure plate 3 is provided at both the upper and lower ends of the pressure-bearing frame 2. The front end of the pressure-bearing frame 2 is provided with a traveling component 4. The bottom sides of the support 1 are provided with guide rail components 5. The rear end of the pressure-bearing frame 2 is provided with a high-pressure container 6, which is installed at the rear end of the top of the support 1. The rear end of the support 1 is provided with an oil tank 7. The top of the oil tank 7 is provided with an oil pump group 9. The oil tank 7 is provided with a hydraulic component. The rear end side of the oil tank 7 is provided with a control pump group 13. The side of the control pump group 13 is provided with a cooling filter system 131.

[0019] The hydraulic components include a booster 8, a control valve assembly 11, a drive pump assembly 12, a control pump assembly 13, a second cooling and filtration system 14, and a pre-pressurization pump 15. The booster 8 is located on one side of the oil pump assembly 9, and the control valve assembly 11 is located on one side of the rear end of the booster 8. A reversing cartridge valve assembly 111 is located on the top of the control valve assembly 11. The drive pump assembly 12 is located at the rear end of the oil tank 7, and the second cooling and filtration system 14 is located on one side of the oil tank 7. The pre-pressurization pump 15 is located on one side of the second cooling and filtration system 14.

[0020] The rear end of the oil pump group 9 is equipped with a pressure relief valve group 10, which includes a high-pressure valve group, a high-pressure proportional pressure relief group, a safety pressure relief valve, and pipelines.

[0021] Specifically,

[0022] An oil-water isolation device is installed inside the high-pressure vessel 6 to separate the pressurized medium from the working medium. The oil-water isolation device includes a barrel opening, an isolation sleeve, a barrel bottom, and a support barrel. The isolation sleeve is made of oil-resistant nitrile rubber.

[0023] Place the workpiece to be pressed into the isolation sleeve of the oil-water isolation device and place it in the working medium. Start the walking component 4 to push the pressure frame to move it to the outside of the high pressure vessel 6. The pressure plate 3 covers the upper and lower plugs of the high pressure vessel 6 respectively to bear the axial force transmitted by the upper and lower plugs.

[0024] The upper plug is lowered by the lifting mechanism to close the high-pressure container 6. The lower plug is reset by a rectangular spring structure. Both the upper and lower plugs adopt a floating structure.

[0025] Start the pre-pressurization pump 15 to fill the high-pressure container 6 with liquid. The residual air in the container is discharged through the venting device on the upper plug until a small amount of liquid is discharged from the venting port, and the venting valve core closes automatically.

[0026] First, the pressure is increased to a pre-pressurization pressure of 0-8MPa by the pre-pressurization pump 15, and then switched to the booster 8, which increases the pressure to the maximum working pressure of 400MPa. During the pressure holding process, the pressure is automatically replenished when it drops to the set lower limit.

[0027] The pressure is released by the pressure relief valve group 10 according to the set parameters. The time to release pressure from the working pressure to 1.5MPa can be set within 3-60 minutes. The pressure release method can be adopted in stages. The pressure release process is automatically controlled by PLC throughout.

[0028] When the pressure is reduced to 2-0MPa, the oil pump group 9 is started to extract the remaining liquid in the ultra-high pressure container 6 until the upper plug is opened and then it stops. At the same time, the gas generated by the pressing parts is discharged, the upper plug descends to reset, and the lower plug rises to reset.

[0029] The pressure-bearing frame 2 is moved out by the walking component 4, the upper plug is opened, and the pressed part is taken out.

[0030] During the pressing process, the cooling pump is started when the oil temperature of the booster 8 is ≥45℃, and stopped when it is ≥60℃. Cooling is stopped when it is ≤40℃. The heating device is started when the oil temperature is ≤5℃ and stopped when it is ≥15℃. During the cooling process, the oil is circulated and filtered through a 10-micron combined filter.

[0031] The booster 8 is a reciprocating plunger type structure with a driving pressure of no more than 28MPa. During the boosting process, the boosting speed is adjusted by a manual flow regulating valve. When the pressure is over-pressurized, the system automatically overflows and returns oil and stops. During the pressure holding phase, the pressure drop in the high-pressure vessel 6 is no more than 5MPa within the 300s pressure holding period. During the pressure holding phase, the booster system's drive pump stops working.

[0032] The pressure relief valve assembly 10 includes a high-pressure proportional pressure relief assembly, a hydraulic safety valve, a manual shut-off valve, and a burst valve. During pressure relief, the high-pressure proportional pressure reducing valve controls the pressure on the proportional pressure relief valve assembly to a low pressure value not exceeding 28 MPa.

[0033] The oil pumping system uses a built-in large-diameter oil pumping valve and is equipped with an oil pump. The oil pumping process is delayed until the upper plug is opened and then stops to ensure that the isolation sleeve returns to its original state before pressurization.

[0034] Furthermore,

[0035] The hydraulic system consists of a pressurization system, a cooling, filtration and heating system, a pressure relief system, a hydraulic control system, and an oil pumping system.

[0036] The main features of this hydraulic system are: the pressurization system is divided into a booster system and a drive system, which are independent of each other, ensuring the safety and reliability of the drive pump group 12, control valve group 11, reversing cartridge valve group 111, etc.

[0037] The main pump and control pump unit 13 are both placed on the pit floor to ensure that the oil pump does not run dry, thus extending its service life and facilitating replacement and maintenance. The high-pressure oil pump and oil tank 7 are connected using a flexible connection method.

[0038] (v) Pressurization system, which realizes the main functions of press pre-pressurization, pressurization, pressure holding and pressure compensation.

[0039] The pressurization system of this press consists of two systems:

[0040] A drive system that provides hydraulic fluid to the booster 8 and control valves is provided, with a separate oil tank 7 and system. The fluid is used solely to supply hydraulic fluid for the booster 8 and valve control fluid.

[0041] Another system is a pressurization system that replenishes and pressurizes the hydraulic oil supplied to the ultra-high pressure vessel 6.

[0042] The oil tanks 7 of the two systems are separate and do not communicate with each other, so as to ensure that the working oil in the drive oil circuit of the turbocharger 8 and the ultra-high pressure vessel 6 circulates independently, thereby ensuring the cleanliness of the oil and reducing the failure of the drive system. It can also avoid contamination caused by the rupture of the rubber sleeve inside the ultra-high pressure vessel 6 of the pressed parts.

[0043] The high-pressure booster 8 has a maximum working pressure of 400MPa. The main seal of booster 8 has a service life of ≥2 years, and its structure adopts a reciprocating plunger-type booster structure.

[0044] The through-hole high-pressure cylinder and the pull rod design of the inlet and outlet valve end caps eliminate the risk of explosion;

[0045] The reciprocating commutation adopts high-precision non-contact proximity switch control, a pressure-resistant inductive proximity switch, which is stable and reliable; it replaces the traditional strike bar signal, differential pressure signal, time signal, etc.

[0046] Equipped with a manual flow control valve, pressure sensor, and pressure gauge. The booster drive flow can be manually adjusted to change the required pressurization rate.

[0047] When the pressure is increased to 400MPa, the driving pressure is no more than 28MPa. The pressure sensor automatically detects this, and if the pressure exceeds the limit, the oil will automatically overflow back to the oil tank 7 and the machine will stop.

[0048] The booster 8 drives an oil pump as a single pump combination, a manually operated variable pump. The required boosting speed can be changed by manually adjusting the pump flow rate.

[0049] The independent pre-pressurization pump set is a single pump combination. The starting high-pressure manual variable pump has a specification of 25ml / rpm, and the matching motor is N=5.5kW. The pre-pressurization pressure is 0-8Mpa (adjustable). After pre-pressurization is completed, oil is supplied to the high-pressure chamber 8 of the intensifier, and the intensifier pressurizes to the working pressure.

[0050] The drive system consists of a pump assembly, with the pump being a Huade hydraulic 117ml / r pump and a matching motor with N=75kW. During pressure maintenance, the pump stops working to save energy.

[0051] Pressurization process: When the pre-pressurization pressure is reached, the oil supply is reversed → the pressure is increased to the working pressure by the booster 8 → pressure is maintained (or automatic pressure compensation) → automatic pressure relief → oil extraction.

[0052] The pre-pressurization pressure is 0-8 MPa (adjustable). After pre-pressurization is completed, the oil supply to the high-pressure chamber of the steering turbocharger is controlled by the pre-pressurization valve group.

[0053] During pressure holding, if a pressure drop occurs, the booster will start working when the pressure drops to the set lower limit of the working pressure, automatically replenishing the pressure to the set working pressure value and then stopping. During the commissioning and acceptance of the press, the pressure drop should not exceed 5MPa within the 300s pressure holding time.

[0054] The high-pressure valve assembly integrates a pre-pressurization valve and a high-pressure oil inlet circuit. Its main function is to collect and divide the high and low pressure oil circuits, simplify the pipeline, and improve safety.

[0055] The pressurization system piping is connected by flanges, and the sealing structure is a metal hard seal structure.

[0056] Each oil tank 7 is equipped with a level gauge and an air filter; a sponge layer is installed between the panel and the side panel of the oil tank 7 to prevent dust from entering the oil tank 7.

[0057] The high-pressure pipeline of the whole machine is made of 30CrMnSiA forgings, which are first forged and then machined by deep hole boring to ensure safe use.

[0058] (vi) Cooling, filtration and heating systems

[0059] The press is equipped with a cooling, filtration and heating system to automatically cool, filter and heat the drive system.

[0060] The cooling heat exchanger of the drive system adopts a plate heat exchanger with high heat transfer efficiency, low heat loss, and compact structure; ensuring that the oil temperature is below 50 degrees Celsius. The factory setting is that the cooling pump starts when the temperature is ≥45℃, stops when the temperature is ≥60℃, and stops when the temperature is ≤40℃.

[0061] The oil filter is located at the oil outlet and is a high-precision combined filter with a one-way valve, with a filtration accuracy of 10 microns.

[0062] The system can be circulated and filtered during the cooling process or when the cooling water supply is stopped and cooling is not performed.

[0063] Each oil tank 7 is equipped with a heating device that automatically heats the oil when the temperature is too low, ensuring the press operates normally. The factory setting is to start at ≤5℃ and stop at ≥15℃.

[0064] (vii) Pressure relief system

[0065] It consists of a high-pressure valve group, a high-pressure proportional pressure relief group, a safety pressure relief valve, and pipelines, etc., to achieve the pressure relief process requirements.

[0066] The main feature of the proportional pressure relief valve assembly is that it achieves fully automatic and precise control of the pressure relief speed. Starting from the highest working pressure (400MPa), the pressure relief speed is automatically and precisely controlled by the PLC throughout the entire process.

[0067] Proportional control of depressurization speed has been achieved. By setting the depressurization pressure and time values ​​on the PLC, depressurization is automatically performed according to the pressure and time (speed) requirements; and segmented proportional depressurization control can be performed in combination with the requirements of the stepped curve.

[0068] The depressurization speed remains constant. This overcomes the shortcomings of the old method, where the depressurization speed varied due to differences in the volume, quantity, and compression ratio of the loaded products when pressing products of the same specification, thus strictly ensuring the pressing process of the products.

[0069] The pressure relief speed adjustment is simple and convenient, making it more suitable for the production of various products. The old-style pressure relief valve structure required manual and repeated adjustments of the throttle valve when pressing products of different materials, sizes, and shapes, which was time-consuming and labor-intensive; and it could not accurately achieve the required pressure relief speed.

[0070] The system is more reliable and stable. It fundamentally solves the main problems of high failure rate and short lifespan of old-style pressure relief valves; it can maintain reliable and stable operation for a longer period of time (more than 1 year).

[0071] The function of a high-pressure proportional pressure reducing valve is to ensure that the proportional pressure relief valve assembly is subjected to a set low pressure value (usually not higher than 28MPa) during pressurization and depressurization, so that it is not affected by the working pressure, effectively improving its service life. At the same time, it ensures that the pressure relief rate is linear (a straight line, or a curve if there is no pressure reducing valve) under fixed damping conditions during high-pressure depressurization.

[0072] The proportional pressure relief valve assembly is used to control the proportional pressure relief function throughout the entire process. It consists of a large-diameter proportional relief valve (ATOS, Italy), a hydraulic valve block, a filter, an accumulator, etc.

[0073] When depressurizing from the working pressure (not less than 10MPa) to 1.5MPa, the time can be set from 3 to 60 minutes; the depressurization can also be set in stages (factory setting 3 depressurization modes).

[0074] The high-pressure valve assembly consists of a set of hydraulically controlled safety valves, manual shut-off valves, and burst valves; it reduces high-pressure pipelines, improves safety, and reduces maintenance time. A set of hydraulically controlled pressure relief valves is used to achieve power failure or emergency pressure relief.

[0075] An emergency manual pressure relief valve and a direct-reading ultra-high pressure gauge are installed and placed on the workbench to monitor equipment operation and protect equipment safety; at the same time, they can also be used as a temporary pressure relief valve when the automatic pressure relief valve fails.

[0076] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0077] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A hydraulic system for a dual-medium cold isostatic press, comprising a support (1), a pressure-bearing frame (2), and a pressure-bearing plate (3), characterized in that: The support (1) is provided with a pressure-bearing frame (2) on the outside. The pressure-bearing frame (2) is provided with pressure plates (3) at both the upper and lower ends. The pressure-bearing frame (2) is provided with a walking component (4) at the front end. The support (1) is provided with guide rail components (5) on both sides at the bottom. The pressure-bearing frame (2) is provided with a high-pressure container (6) at the rear end. The high-pressure container (6) is installed at the rear end of the top of the support (1). The support (1) is provided with an oil tank (7) at the rear end. The oil tank (7) is provided with an oil pump group (9) at the top. The oil tank (7) is provided with a hydraulic component. The oil tank (7) is provided with a control pump group (13) on one side of the rear end. The control pump group (13) is provided with a cooling filter system (131) on one side.

2. The hydraulic system for a dual-medium cold isostatic press according to claim 1, characterized in that: The hydraulic components include a booster (8), a control valve group (11), a drive pump group (12), a control pump group (13), a second cooling and filtration system (14), and a pre-pressurization pump (15). The booster (8) is provided on one side of the oil pump group (9), the control valve group (11) is provided on one side of the rear end of the booster (8), the reversing cartridge valve group (111) is provided on the top of the control valve group (11), the drive pump group (12) is provided at the rear end of the oil tank (7), the second cooling and filtration system (14) is provided on one side of the oil tank (7), and the pre-pressurization pump (15) is provided on one side of the second cooling and filtration system (14).

3. The hydraulic system for a dual-medium cold isostatic press according to claim 2, characterized in that: The oil pump group (9) is provided with a pressure relief valve group (10) at its rear end. The pressure relief valve group (10) includes a high-pressure valve group, a high-pressure proportional pressure relief group, a safety pressure relief valve and pipelines.

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