Hydraulic-electric hydraulic combined forming device and method for thin-walled parts

Abstract

The present application belongs to the technical field of thin-walled part forming, and particularly relates to a hydraulic-electric hydraulic compound forming device and method for thin-walled parts. The device comprises a female die, a liquid chamber, a pressure ring, a discharge mechanism and a hydraulic system. The discharge mechanism comprises a power supply assembly, at least one pair of electrodes electrically connected to the power supply assembly, the electrodes being arranged in the side wall or bottom wall of the liquid chamber through an insulating bushing and extending into the accommodating cavity, and a metal wire connected between the electrodes for generating an electric explosion shock wave. By integrating hydraulic forming and electric hydraulic forming in the same station, the liquid chamber simultaneously assumes the dual functions of a hydraulic pressurizing chamber and an electric hydraulic discharge chamber, without the need to change the station, transfer the blank, or re-establish the sealing condition, thereby effectively shortening the production cycle, reducing equipment investment and floor space, and avoiding positioning deviation during the blank transfer process.

Description

Technical Field

[0001] This invention belongs to the field of thin-walled part forming technology, specifically relating to a hydraulic-electrohydraulic composite forming device and method for thin-walled parts. Background Technology

[0002] With the rapid development of new energy vehicles, energy storage systems, aerospace, and high-power electronic devices, the demand for large, thin-walled, complex components, such as liquid-cooled plates, heat dissipation substrates, and microchannel heat exchangers, is becoming increasingly urgent. These components typically have large planar dimensions (over 300 mm), thin wall thickness (0.5–3.0 mm), and complex cavity structures (including deep flow channels, narrow grooves, sharp edges, and microchannels), placing extremely high demands on forming accuracy, filling integrity, and thickness uniformity.

[0003] Currently, the industry mainly uses hydroforming and electro-hydraulic forming technologies for the plastic forming of the aforementioned thin-walled complex components, each with its own significant technical limitations. In actual production, the forming requirements of some complex thin-walled parts cannot be met by either of these single processes. If hydroforming and electro-hydraulic forming are used as two independent processes, they need to be completed on different equipment or at different workstations. The sheet metal needs to undergo disassembly, transfer, repositioning, and re-clamping and sealing between processes, which not only increases the production cycle and equipment investment, but also inevitably introduces cumulative positioning errors through multiple clamping and positioning, affecting the dimensional accuracy and consistency of the final formed thin-walled parts. At the same time, the transfer and waiting between processes also increase the risk of scratches, oxidation, and contamination on the sheet metal surface, reducing the product qualification rate. Summary of the Invention

[0004] The purpose of this application is to provide a hydraulic-electro-hydraulic composite forming device and method for thin-walled parts, which can effectively overcome the inherent defects of insufficient filling capacity of hydraulic forming and low space attenuation and low energy utilization efficiency of electro-hydraulic forming, and realize efficient and precise forming of large-size complex thin-walled parts.

[0005] In a first aspect, this application provides a hydraulic-electro-hydraulic composite forming apparatus for thin-walled parts, comprising: A die, the lower surface of which is provided with a forming cavity corresponding to the target shape of the thin-walled part to be formed; A liquid chamber is disposed below the concave mold, and the liquid chamber has an upward-facing receiving cavity for containing a liquid medium; A pressure ring is disposed between the liquid chamber and the die, and is used to press the outer periphery of the sheet material to be formed and seal the receiving cavity of the liquid chamber; A discharge mechanism, comprising a power supply component and at least one pair of electrodes electrically connected to the power supply component, wherein the electrodes pass through an insulating bushing in the side wall or bottom wall of the liquid chamber and extend into the receiving cavity, and a metal wire for generating a shock wave by an electric explosion is connected between the electrodes. A hydraulic system, which is connected to the liquid chamber, is used to inject a liquid medium into the liquid chamber and apply a controllable quasi-static pressure.

[0006] Optionally, the electrode assembly includes multiple pairs of electrodes, which are spaced apart circumferentially and / or radially along the liquid chamber, with the metal wire between each pair of electrodes located at different positions within the liquid chamber cavity; the insulating bushing is fitted onto the portion of the electrode that passes through the liquid chamber wall.

[0007] Optionally, a sealing structure is provided between the pressure ring and the upper end face of the liquid chamber, the sealing structure including a sealing ring disposed on the lower surface of the pressure ring and / or the upper end face of the liquid chamber; the pressure ring is pressed against the upper end face of the liquid chamber by fasteners or a hydraulic clamping mechanism.

[0008] Optionally, the hydraulic system includes a booster, a reservoir, pipelines, and a control valve assembly; the booster is connected to the receiving cavity of the liquid chamber through the pipelines, and the control valve assembly is disposed on the pipelines for controlling the injection, pressure holding, and pressure release of the liquid medium.

[0009] Optionally, the power supply component includes a high-voltage DC power supply, a capacitor bank, and a discharge switch; the high-voltage DC power supply is used to charge the capacitor bank to a preset voltage, and the discharge switch is disposed in the discharge circuit between the capacitor bank and the electrode.

[0010] Secondly, this application provides a hydraulic-electrohydraulic composite forming method for thin-walled parts, employing the apparatus described above, and including the following steps: S1. Place the sheet material to be formed between the liquid chamber and the die, and press the outer periphery of the sheet material with the pressure ring to seal the receiving cavity of the liquid chamber; S2. The liquid medium is injected into the liquid chamber through the hydraulic system and a quasi-static pressure is applied, so that the sheet metal undergoes plastic deformation into the forming cavity of the die under the action of liquid pressure, forming the basic outline of the target shape. S3. After the sheet material is basically attached to the forming cavity under hydraulic pressure, the hydraulic pressure in the liquid chamber is not removed, so that the sheet material is under stress under continuous liquid pressure. S4. While maintaining the hydraulic pressure, high-voltage electrical energy is instantaneously released to the electrode through the power supply device, causing the metal wire to explode electrically, generating a high-energy shock wave in the liquid medium in the liquid chamber. The shock wave and the continuous hydraulic pressure work together to act on the sheet material, driving the sheet material to further fill the bottom and corner areas of the forming cavity with the mold. S5. After the electro-hydraulic final forming is completed, the hydraulic pressure in the liquid chamber is released, the liquid medium is drained, the mold is opened, and the formed thin-walled part is taken out.

[0011] Optionally, in step S2, the liquid medium is pure water or deionized water; the pressure of the hydraulic preforming is 2~15 MPa.

[0012] Optionally, in step S4, the discharge energy of the discharge device is 5~30 kJ; the metal wire is made of aluminum wire, copper wire or iron wire, and has a diameter of 0.5~2.0 mm.

[0013] Optionally, the sheet material is aluminum alloy, stainless steel, titanium alloy or copper alloy; the thickness of the sheet material is 0.5~3.0 mm; the planar dimensions of the sheet material are not less than 300 mm × 300 mm.

[0014] Optionally, in step S4, the electro-hydraulic final shaping includes one or more discharges; when multiple discharges are performed, the hydraulic pressure in the liquid chamber is not removed between adjacent discharges.

[0015] The beneficial effects of this application are: The hydraulic-electro-hydraulic composite forming apparatus for thin-walled parts provided in the first aspect of this application integrates hydraulic forming and electro-hydraulic forming into the same station. The liquid chamber simultaneously serves as both a hydraulic pressurization chamber and an electro-hydraulic discharge chamber. This eliminates the need to change stations, transfer blanks, or re-establish sealing conditions, effectively shortening the production cycle, reducing equipment investment and floor space, and avoiding positioning deviations during blank transfer.

[0016] The hydraulic-electro-hydraulic composite forming method for thin-walled parts provided in the second aspect of this application utilizes a two-pass, one-station process of hydraulic pre-forming, pressure holding, and electro-hydraulic final forming. Under pressure holding conditions, it achieves the synergistic effect of hydraulic pressure and electro-hydraulic shock waves. There is no pressure interruption, no sheet metal transfer, and the process is continuous with high forming efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the hydraulic-electro-hydraulic composite forming device provided in the embodiments of this application; Figure 2 This is a schematic diagram of the composition structure of the hydraulic system provided in the embodiments of this application; Figure 3This is a sample diagram of the hydraulic-electro-hydraulic composite molding provided in Embodiment 1 of this application; Figure 4 A sample diagram of an electrohydraulic forming specimen provided in Comparative Example 1 of this application; Figure 5 This is a comparison diagram of the filling rate of the die flow channel for the samples of Example 1 and Comparative Example 1 of this application; Figure 6 Cross-sectional profiles of the shaped thin-walled parts of Embodiment 1 and Comparative Example 1 provided in this application; Figure 7 Cross-sectional thickness test diagrams of the shaped thin-walled parts of Embodiment 1 and Comparative Example 1 provided in this application.

[0018] In the diagram: 1-1, sheet metal; 100, die; 200, liquid chamber; 300, pressure ring; 400, discharge mechanism; 410, power supply assembly; 420, electrode; 430, metal wire; 440, insulating bushing; 500, hydraulic system; 510, booster; 520, liquid storage tank; 530, pipeline; 541, inlet valve; 542, pressure holding check valve; 543, pressure relief valve. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0020] Before introducing the embodiments of this application, the background technology involved in this application will be introduced first.

[0021] In the field of hydroforming technology, hydroforming utilizes a liquid medium to apply quasi-static uniform pressure to sheet metal, causing it to deform and conform to the mold cavity. This technology has advantages such as uniform pressure distribution, stable forming process, and relatively low equipment cost, and has been widely used in the forming of shallow-cavity, high-curvature parts. However, when faced with cavities with complex geometric features such as deep runners, narrow grooves, and sharp internal angles, hydroforming exhibits significant insufficient filling capacity: because the liquid pressure is a quasi-static load, the local driving force of the sheet metal at the bottom of the cavity and in the corner areas is limited, making it difficult for material to fully flow into the bottom of the deep cavity and the transition area of ​​sharp corners. This results in obvious under-molding defects in the formed thin-walled parts, and the filling rate cannot meet the requirements of high-precision components. If the filling effect is improved simply by increasing the hydraulic pressure, the sheet metal will be subjected to excessive tensile stress in a large area, which can easily lead to excessive thinning or even cracking, and the forming window is extremely narrow. Therefore, traditional hydroforming technology has an inherent bottleneck in the high-precision forming of complex-cavity thin-walled parts.

[0022] In the field of electro-hydraulic forming technology, electro-hydraulic forming (also known as electro-hydraulic impact forming) utilizes high-voltage pulse discharge to cause an electrical explosion of a metal wire in a liquid, generating a high-energy shock wave that drives the sheet metal to be molded at high speed. This technology has advantages such as extremely high loading rate (microsecond level), large peak pressure, and improved sheet metal forming limit compared to quasi-static conditions, making it particularly suitable for reinforcing and filling localized areas that are difficult to form. However, electro-hydraulic forming technology faces the following prominent problems in engineering applications: First, the shock wave exhibits a significant spatial attenuation effect when propagating in a liquid medium, with its pressure amplitude decreasing sharply as the propagation distance increases. This leads to a significant difference in impact force between the central and edge regions of large-size sheet metal, resulting in poor forming uniformity. Uneven filling from the center to the edge has become a common problem restricting its application in large-size components. Second, due to the extremely short duration of the shock wave (usually tens of microseconds), the effective forming work provided by a single discharge is limited. For cavities with large depths or sheets with large areas, a single discharge often cannot achieve sufficient filling. Blindly increasing the discharge energy can lead to excessive thinning of the sheet metal in certain areas, increased springback, or even breakage. Third, electro-hydraulic forming involves transient impact loading. After the shock wave ends, the sheet metal lacks continuous external force support. The material in the molded area is prone to springback under residual stress, affecting the final forming accuracy. In actual production, the forming requirements of some complex thin-walled parts cannot be met by any single process mentioned above. If two independent processes, hydraulic forming and electro-hydraulic forming, are used, they need to be completed on different equipment or stations. The sheet metal needs to undergo disassembly, transfer, repositioning, and re-clamping and sealing between processes. This not only increases the production cycle and equipment investment, but also inevitably introduces cumulative positioning errors due to multiple clamping and positioning, affecting the dimensional accuracy and consistency of the final formed thin-walled parts. At the same time, the transfer and waiting between processes also increase the risk of scratches, oxidation, and contamination on the sheet metal surface, reducing the product qualification rate.

[0023] In summary, related technologies suffer from insufficient capacity for filling complex cavities in hydraulic forming and low space attenuation and energy utilization in electro-hydraulic forming. Furthermore, the separate implementation of these two processes leads to low efficiency and poor positioning accuracy. To address these issues, this application provides a hydraulic-electro-hydraulic composite forming apparatus and method for thin-walled parts.

[0024] like Figure 1 and Figure 2 As shown, the first aspect of this application provides a hydraulic-electrohydraulic composite forming apparatus for thin-walled parts, comprising: The die 100 has a forming cavity on its lower surface that corresponds to the target shape of the thin-walled part to be formed. Liquid chamber 200 is disposed below the cavity 100. Liquid chamber 200 has an upward-facing receiving cavity for receiving liquid medium. A pressure ring 300 is disposed between the liquid chamber 200 and the die 100 to press the outer periphery of the sheet material 1-1 to be formed and to seal the receiving cavity of the liquid chamber 200. The discharge mechanism 400 includes a power supply component 410 and at least one pair of electrodes 420 electrically connected to the power supply component 410. The electrodes 420 pass through the side wall or bottom wall of the liquid chamber 200 through an insulating bushing 440 and extend into the receiving cavity. A metal wire 430 for generating a shock wave by an electric explosion is connected between the electrodes 420. Hydraulic system 500 is connected to liquid chamber 200 and is used to inject liquid medium into liquid chamber 200 and apply controllable quasi-static pressure.

[0025] The first aspect of this application provides a hydraulic-electro-hydraulic composite forming apparatus for thin-walled parts. In the compression forming stage, the hydraulic system 500 injects a liquid medium into the sealed liquid chamber 200 and applies quasi-static pressure, causing the sheet metal 1-1 to undergo plastic deformation towards the cavity of the upward-facing die 100 under uniform pressure, thus completing the overall contour pre-forming. In the electro-hydraulic forming stage, while maintaining the hydraulic pressure, the power supply equipment instantaneously releases high-voltage electrical energy to the electrodes 420 that extend into the liquid chamber 200 through the insulating bushing 440, causing the metal wires 430 between the electrodes 420 to undergo an electrical explosion, generating a high-energy shock wave in the liquid medium. This shock wave, together with the continuously existing hydraulic pressure, acts on the sheet metal 1-1, driving the sheet metal 1-1 to further adhere to the die at high speed, achieving high-precision final forming of complex cavities.

[0026] In some embodiments, the electrode 420 assembly includes multiple pairs of electrodes 420, which are spaced apart circumferentially and / or radially along the liquid chamber 200, and the metal wire 430 between each pair of electrodes 420 is located at different positions within the receiving cavity of the liquid chamber 200; an insulating bushing 440 is sleeved on the portion of the electrode 420 that passes through the wall of the liquid chamber 200.

[0027] Specifically, when multiple pairs of electrodes 420 discharge simultaneously or in a preset sequence, the metal wires 430 between each electrode 420 undergo electrical explosions, generating multiple shock waves at different locations within the liquid chamber 200. These shock waves superimpose and propagate in the liquid medium, forming a more uniform dynamic pressure field. This ensures that each area of ​​the sheet 1-1 receives sufficient forming driving force, effectively solving the problem of insufficient filling in the edge area of ​​large-size sheet 1-1 due to the attenuation of shock waves with distance.

[0028] In one embodiment, four pairs of electrodes 420 (a total of eight electrodes 420) are evenly spaced along the circumference of the liquid chamber 200. Specifically, eight electrode mounting holes 420 are equally spaced along the circumference on the sidewall of the liquid chamber 200. Two electrodes 420 in each pair are arranged adjacent to each other with a spacing of 30-80 mm, and a metal wire 430 connects each pair of electrodes 420. The four pairs of electrodes 420 are located in the four quadrant regions of the liquid chamber 200, so that the position of the metal wire 430 covers the main forming area of ​​the sheet 1-1. The four pairs of electrodes 420 can discharge simultaneously or sequentially according to a preset time sequence. When discharging simultaneously, the four metal wires 430 undergo an electrical explosion at the same moment, generating four shock waves at four different locations within the liquid chamber 200. The four shock waves propagate outwards in the liquid and superimpose on the lower surface of the sheet 1-1, forming a relatively uniform dynamic pressure field. The superposition effect of this multi-source shock wave effectively overcomes the problem of single shock wave attenuation with increasing propagation distance, ensuring sufficient forming driving force in both the central and edge regions of large-size sheet metal 1-1 (e.g., 620 mm × 460 mm), thus solving the common technical problem of uneven filling between the center and edge of large-size components. If a sequential discharge method is used, triggering the discharge switches of each pair of electrodes 420 sequentially at preset time intervals (e.g., 10~100 μs) allows the shock waves to act on different regions of sheet metal 1-1 in a specific order, enabling directional compensation for under-molding in specific regions.

[0029] The insulating bushing 440 is cast from epoxy resin. Its inner diameter is clearance-fitted with the outer diameter of the electrode 420 (gap 0.1~0.3mm), and its outer diameter is interference-fitted with the mounting hole on the wall of the liquid chamber 200 (interference 0.05~0.1mm), ensuring both sealing and insulation functions. The wall thickness of the insulating bushing 440 is not less than 5mm, and its withstand voltage rating is not less than 30 kV.

[0030] In some embodiments, a sealing structure is provided between the pressure ring 300 and the upper end face of the liquid chamber 200. The sealing structure includes a sealing ring disposed on the lower surface of the pressure ring 300 and / or the upper end face of the liquid chamber 200. The pressure ring 300 is pressed against the upper end face of the liquid chamber 200 by fasteners or a hydraulic clamping mechanism.

[0031] Specifically, the edge ring applies sufficient clamping force to the outer periphery of the sheet 1-1 via fasteners or a hydraulic clamping mechanism, forming a reliable sealing interface between the sheet 1-1 and the upper surface of the liquid chamber 200. Under the clamping force, the sealing ring undergoes elastic deformation, filling the microscopic gap between the sheet 1-1 and the liquid chamber 200, preventing the liquid medium from permeating outward under high pressure, thereby maintaining the continuous stability of the pressure inside the liquid chamber 200 and providing a sealing guarantee for pressure maintenance during the pressure holding stage.

[0032] In some embodiments, the pressure ring 300 is a rectangular annular structure, made of 45# steel or 40Cr alloy steel, with a surface hardness of HRC28~32 after tempering. An annular sealing groove is machined on the lower surface of the pressure ring 300, and an O-ring fluororubber sealing ring with a cross-sectional diameter of 3~5 mm is installed inside the sealing groove. A sealing mating surface is machined on the upper end face of the liquid chamber 200 corresponding to the sealing ring, with a surface roughness Ra≤0.8 μm. The pressure ring 300 is pressed against the upper end face of the liquid chamber 200 by four hydraulic clamping cylinders. The clamping force of each hydraulic clamping cylinder is not less than 50 kN, and the total clamping force is not less than 200 kN, ensuring that no slippage or liquid leakage occurs at the outer periphery of the sheet metal 1-1 under a hydraulic pressure of 15 MPa. The hydraulic clamping cylinders are uniformly controlled by a control system to achieve synchronous clamping and release.

[0033] In some embodiments, the hydraulic system 500 includes a booster 510, a reservoir 520, a pipeline 530, and a control valve assembly; the booster 510 is connected to the receiving cavity of the liquid chamber 200 through the pipeline 530, and the control valve assembly is disposed on the pipeline 530 for controlling the injection, pressure holding, and pressure release of the liquid medium.

[0034] Specifically, the booster 510 is a pneumatic booster with a boost ratio of 10:1. When the input air pressure is 0.6 MPa, the output hydraulic pressure can reach 6 MPa, with a maximum output pressure of 20 MPa. The liquid storage tank 520 has a volume of 5~10 L and includes a built-in filter and level sensor. The high-pressure hose has a pressure resistance rating of not less than 25 MPa and an inner diameter of 6~10 mm. The inlet valve 541 is a two-position, normally closed, solenoid ball valve with a response time ≤50 ms. The control valve assembly includes an inlet valve 541, a pressure-holding check valve 542, and a pressure relief valve 543. The pressure-holding check valve 542 is located between the outlet of the booster 510 and the liquid chamber 200 to prevent backflow of liquid in the liquid chamber 200 during the pressure-holding stage. The pressure relief valve 543 is an electromagnetic relief valve, and its opening pressure can be set by the control system. During the hydraulic preforming stage, the inlet valve 541 is opened and the pneumatic booster 510 is started through the control system (industrial computer or PLC controller). Pure water in the storage tank 520 is injected into the liquid chamber 200 through a high-pressure hose and the inlet valve 541. As liquid is continuously injected, the pressure in the liquid chamber 200 gradually increases, and the sheet metal 1-1 deforms into the cavity of the die 100 under uniform hydraulic pressure. The control system monitors the pressure in the liquid chamber 200 in real time through a pressure sensor. When the pressure reaches the preset value, the inlet valve 541 is closed, and the pressure-holding check valve 542 automatically locks the liquid in the liquid chamber 200, entering the pressure-holding state. During the pressure holding stage, the pressure in the liquid chamber 200 is maintained by the pressure holding check valve 542, and the pressure fluctuation does not exceed ±0.1 MPa. After the electro-hydraulic final forming is completed, the control system opens the pressure relief valve 543, and the liquid in the liquid chamber 200 flows back to the liquid storage tank 520 through the pressure relief valve 543. The pressure in the liquid chamber 200 drops to zero, and then the mold can be opened to remove the formed thin-walled part.

[0035] In some embodiments, the power supply component 410 includes a high-voltage DC power supply, a capacitor bank, and a discharge switch; the high-voltage DC power supply is used to charge the capacitor bank to a preset voltage, and the discharge switch is disposed in the discharge circuit between the capacitor bank and the electrode 420.

[0036] Specifically, the discharge equipment includes a high-voltage DC power supply (e.g., output voltage 0~25 kV, output current 0~10 mA), a capacitor bank (e.g., composed of four 50μF / 25 kV pulse capacitors connected in parallel, with a total capacitance of 200 μF), a discharge switch (trigger-type spark gap switch, trigger voltage 1~3 kV, conduction time <1 μs), and a coaxial discharge cable (impedance matching to reduce energy transmission loss).

[0037] A high-voltage DC power supply charges the capacitor bank through a current-limiting resistor, with a charging time of approximately 10–30 seconds. During the charging phase, the high-voltage DC power supply slowly charges the capacitor bank, storing electrical energy in the capacitors as electric field energy. When the control system issues a discharge command, a trigger pulse is applied to the trigger-type spark gap switch, causing the spark gap to break down and conduct. The electrical energy stored in the capacitor bank is released within a very short time (less than 5 μs) through the coaxial cable and electrode 420. The transient current peak can reach 100–300 kA, generating extremely high resistance heat (Joule heating) when flowing through the metal wire 430. The metal wire 430 undergoes a phase transition from solid to plasma within 1–3 μs. The plasma expands rapidly, compressing the surrounding water medium to form a shock wave. The initial pressure of the shock wave can reach hundreds of megapascals to gigapascals, attenuating with increasing propagation distance. However, under the superposition of hydraulic pre-pressure, it still has sufficient driving force to further adhere to the mold surface of sheet 1-1 upon reaching it.

[0038] Secondly, this application provides a hydraulic-electro-hydraulic composite forming method for thin-walled parts, employing the above-mentioned apparatus, and including the following steps: S1. Place the sheet material 1-1 to be formed between the liquid chamber 200 and the die 100, and press the outer periphery of the sheet material 1-1 with the pressure ring 300 to seal the receiving cavity of the liquid chamber 200. S2. Liquid medium is injected into liquid chamber 200 through hydraulic system 500 and quasi-static pressure is applied, so that sheet 1-1 undergoes plastic deformation into forming cavity of die 100 under the action of liquid pressure, forming the basic outline of the target shape. S3. After the sheet material 1-1 is basically attached to the forming cavity under the action of hydraulic pressure, the hydraulic pressure in the liquid chamber 200 is not removed, so that the sheet material 1-1 is under stress under the continuous action of liquid pressure. S4. While maintaining hydraulic pressure, high-voltage electrical energy is instantaneously released to electrode 420 through power supply equipment, causing metal wire 430 to explode electrically, generating a high-energy shock wave in the liquid medium in liquid chamber 200. The shock wave and continuous hydraulic pressure work together to act on sheet 1-1, driving sheet 1-1 to further fill the bottom and corner areas of the forming cavity with the mold. S5. After the electro-hydraulic final forming is completed, the hydraulic pressure in the liquid chamber 200 is released, the liquid medium is drained, the mold is opened, and the formed thin-walled part is taken out.

[0039] The second aspect of this application provides a hydraulic-electro-hydraulic composite forming method for thin-walled parts. In the hydraulic preforming stage, the liquid medium forms a uniform quasi-static pressure field in the liquid chamber 200, driving the sheet metal 1-1 to deform uniformly into the cavity of the die 100 to obtain the basic outline of the target shape. This stage mainly completes the macroscopic forming of large areas. In the pressure holding stage, the pressure in the liquid chamber 200 is maintained without being removed, so that the sheet metal 1-1 is in a state of continuous pressure, providing a uniform preload background for the propagation of subsequent shock waves. In the electro-hydraulic final forming stage, the shock wave generated by the electric explosion of the metal wire 430 propagates in the liquid medium with existing hydraulic pressure. The dynamic pressure of the shock wave is superimposed with the continuous static hydraulic pressure to form a composite load of static pressure and dynamic impact, driving the sheet metal 1-1 material to further fill the bottom and corner areas of the flow channel that are difficult to fill fully in the hydraulic preforming stage at high speed, realizing the reinforcement compensation of the local under-molding area.

[0040] In some embodiments, in step S2, the liquid medium is pure water or deionized water; the pressure of hydraulic preforming is 2~15 MPa.

[0041] Specifically, pure water or deionized water is used as the liquid medium, which is inexpensive, environmentally friendly and pollution-free, and has good incompressibility, which is conducive to the uniform transmission of pressure and the efficient propagation of shock waves. The hydraulic pressure is controlled within the range of 2~15 MPa, which can ensure that the sheet 1-1 obtains sufficient pre-deformation, and will not cause excessive thinning or cracking of the sheet 1-1 in the pre-forming stage due to excessive pressure.

[0042] In some embodiments, the deformation rate of sheet 1-1 under hydraulic pressure is quasi-static deformation, with a strain rate not exceeding 1 s⁻¹. The quasi-static deformation rate ensures uniform deformation of sheet 1-1 during the preforming stage, avoiding uneven thickness caused by excessively high local strain rates.

[0043] In some embodiments, in step S4, the discharge energy of the discharge device is 5~30 kJ; the metal wire 430 is made of aluminum wire, copper wire or iron wire, and has a diameter of 0.5~2.0 mm.

[0044] Specifically, the discharge energy is controlled within the range of 5~30 kJ. Combined with the pre-deformation effect of hydraulic preforming, a high filling rate can be achieved at a lower energy level, significantly reducing energy consumption and equipment costs. The diameter of the 430 metal wire is within the range of 0.5~2.0 mm, which ensures the sufficiency of the electro-explosion and the controllability of the shock wave intensity. The superposition effect of the shock wave and hydraulic pressure under the pressure holding state is the core technical feature of this method. This synergistic effect greatly improves the filling rate.

[0045] In some embodiments, the material of sheet 1-1 is aluminum alloy, stainless steel, titanium alloy or copper alloy; the thickness of sheet 1-1 is 0.5~3.0 mm; the planar dimensions of sheet 1-1 are not less than 300 mm × 300 mm.

[0046] Specifically, the application scope is expanded from a single liquid cooling plate to the forming of thin-walled parts made of various metal materials such as aluminum alloy, stainless steel, titanium alloy, and copper alloy, covering a variety of application scenarios such as liquid cooling plates for new energy vehicle power batteries, liquid cooling plates for energy storage systems, liquid cooling plates for aerospace, heat dissipation substrates for electronic devices, and microchannel heat exchangers. The limitation of sheet thickness of 0.5~3.0 mm and planar size of not less than 300 mm×300 mm clarifies that this method is particularly suitable for forming large-size thin-walled complex components, filling the technical gap in efficient and precise forming within this size range.

[0047] In some embodiments, in step S4, electro-hydraulic final shaping includes one or more discharges; when multiple discharges are performed, the hydraulic pressure in the liquid chamber 200 is not removed between adjacent discharges.

[0048] Specifically, the design that allows for multiple discharges makes this method flexible in terms of process. For thin-walled parts with large cavity depths or particularly complex geometries, the forming amount can be gradually accumulated through multiple discharges, avoiding the problem of the sheet material breaking due to excessive energy in a single discharge.

[0049] In some embodiments, the forming method further includes: after step S5, detecting the filling rate of the formed thin-walled part, wherein the formula for calculating the filling rate is: η = S1 / S2 × 100% Wherein, S1 is the area enclosed by the actual cavity cross section and the bottom surface of the formed thin-walled part, and S2 is the theoretical cross-sectional area of ​​the cavity of the die 100; when the filling rate does not reach the preset threshold, steps S3 and S4 are re-executed for supplementary forming.

[0050] Example 1 Sheet material 1-1: 3 pieces, size 400mm×300mm, thickness 1mm; The material of metal wire 430 is aluminum wire; Composite forming: First, hydraulic forming is performed at a pressure of 5MPa, followed by electro-hydraulic forming with discharge energies of 10kJ, 15kJ, and 20kJ, respectively.

[0051] Comparative Example 1 Sheet material 1-1: 3 pieces, size 400mm×300mm, thickness 1mm; The material of metal wire 430 is aluminum wire; Electro-hydraulic forming was performed only, with discharge energies of 10 kJ, 15 kJ, and 20 kJ, respectively.

[0052] The results of the physical test are as follows Figure 3 and Figure 4 As shown, it can be directly observed that the groove structure of the thin-walled part (sample) formed by hydraulic-electro-hydraulic composite molding in Example 1 is more complete and uniform.

[0053] like Figure 5 As shown, in Example 1, the thin-walled part formed by hydraulic-electro-hydraulic composite molding has a higher filling rate of the cavity 100 of the die, indicating that the forming quality of hydraulic-electro-hydraulic composite molding is superior.

[0054] like Figure 6 and Figure 7 As shown, samples with a discharge energy of 20 kJ after hydraulic forming in Example 1 and samples with a discharge energy of 20 kJ in Comparative Example 1 were selected. It can be seen that the minimum thicknesses at measuring points 2 and 8 of the electro-hydraulic formed sample in Comparative Example 1 are 817 μm and 821 μm, respectively, corresponding to a maximum thickness reduction rate of approximately 18.3%. In contrast, the minimum thicknesses at the corresponding positions of the composite formed sample increased to 865 μm and 875 μm, respectively, while the maximum thickness reduction rate decreased to 13.5%. Compared with the single-step electro-hydraulic process, the maximum thickness reduction rate of the composite forming decreased by 4.8 percentage points, a reduction of approximately 26.2%. Meanwhile, the average thickness of the nine measuring points of the composite formed sample in Example 1 is approximately 936.1 μm, higher than the 907.7 μm of the single-step electro-hydraulic forming. Therefore, Example 1, using hydraulic-electro-hydraulic composite forming, has a stronger ability to suppress overall thinning of sheet 1-1, resulting in a more uniform overall thickness of the formed thin-walled part, which is beneficial for improving mechanical strength.

[0055] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0056] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A hydraulic-electrohydraulic composite forming device for thin-walled parts, characterized in that, include: A die (100) has a forming cavity on its lower surface that corresponds to the target shape of the thin-walled part to be formed; Liquid chamber (200), the liquid chamber (200) is disposed below the concave mold (100), the liquid chamber (200) has an upward-facing receiving cavity, the receiving cavity being used to receive a liquid medium; A pressure ring (300) is disposed between the liquid chamber (200) and the die (100) to press the outer periphery of the sheet material (1-1) to be formed and to seal the receiving cavity of the liquid chamber (200); The discharge mechanism (400) includes a power supply component (410) and at least one pair of electrodes (420) electrically connected to the power supply component (410). The electrodes (420) are inserted through an insulating bushing (440) into the side wall or bottom wall of the liquid chamber (200) and extend into the receiving cavity. A metal wire (430) for generating a shock wave by an electric explosion is connected between the electrodes (420). A hydraulic system (500) is connected to the liquid chamber (200) for injecting a liquid medium into the liquid chamber (200) and applying a controllable quasi-static pressure.

2. The hydraulic-electro-hydraulic composite forming apparatus for thin-walled parts according to claim 1, characterized in that, The electrode (420) assembly includes multiple pairs of electrodes (420), which are spaced apart circumferentially and / or radially along the liquid chamber (200). The metal wire (430) between each pair of electrodes (420) is located at different positions within the receiving cavity of the liquid chamber (200). The insulating bushing (440) is fitted onto the portion of the electrode (420) that passes through the wall of the liquid chamber (200).

3. The hydraulic-electro-hydraulic composite forming apparatus for thin-walled parts according to claim 1, characterized in that, The pressure ring (300) is pressed against the upper end face of the liquid chamber (200) by fasteners or a hydraulic clamping mechanism.

4. The hydraulic-electro-hydraulic composite forming apparatus for thin-walled parts according to claim 1, characterized in that, The hydraulic system (500) includes a booster (510), a reservoir (520), a pipeline (530), and a control valve assembly. The booster (510) is connected to the receiving cavity of the liquid chamber (200) through the pipeline (530). The control valve assembly is installed on the pipeline (530) and is used to control the injection, pressure holding, and pressure release of the liquid medium.

5. The hydraulic-electro-hydraulic composite forming apparatus for thin-walled parts according to claim 1, characterized in that, The power supply component (410) includes a high-voltage DC power supply, a capacitor bank, and a discharge switch; the high-voltage DC power supply is used to charge the capacitor bank to a preset voltage, and the discharge switch is disposed in the discharge circuit between the capacitor bank and the electrode (420).

6. A hydraulic-electro-hydraulic composite forming method for thin-walled parts, characterized in that, The apparatus described in any one of claims 1-5 comprises the following steps: S1. Place the sheet material (1-1) to be formed between the liquid chamber (200) and the die (100), and press the outer periphery of the sheet material (1-1) with the pressure ring (300) to seal the receiving cavity of the liquid chamber (200); S2. The liquid medium is injected into the liquid chamber (200) through the hydraulic system (500) and a quasi-static pressure is applied, so that the sheet metal (1-1) undergoes plastic deformation in the forming cavity of the die (100) under the action of liquid pressure, forming the basic outline of the target shape; S3. After the sheet material (1-1) is basically attached to the forming cavity under hydraulic pressure, the hydraulic pressure in the liquid chamber (200) is not removed, so that the sheet material (1-1) is under stress under continuous liquid pressure. S4. While maintaining the hydraulic pressure, high-voltage electrical energy is instantaneously released to the electrode (420) through the power supply device, causing the metal wire (430) to undergo an electrical explosion, generating a high-energy shock wave in the liquid medium in the liquid chamber (200). The shock wave and the continuous hydraulic pressure work together on the sheet material (1-1), driving the sheet material (1-1) to further fill the bottom and corner areas of the forming cavity with the mold. S5. After the electro-hydraulic final forming is completed, the hydraulic pressure in the liquid chamber (200) is released, the liquid medium is drained, the mold is opened, and the formed thin-walled part is taken out.

7. The hydraulic-electro-hydraulic composite forming method for thin-walled parts according to claim 6, characterized in that, In step S2, the liquid medium is pure water or deionized water; the pressure of the hydraulic preforming is 2~15 MPa.

8. The hydraulic-electro-hydraulic composite forming method for thin-walled parts according to claim 6, characterized in that, In step S4, the discharge energy of the discharge device is 5~30 kJ; the metal wire (430) is made of aluminum wire, copper wire or iron wire, and has a diameter of 0.5~2.0 mm.

9. The hydraulic-electro-hydraulic composite forming method for thin-walled parts according to claim 6, characterized in that, The material of the sheet (1-1) is aluminum alloy, stainless steel, titanium alloy or copper alloy; the thickness of the sheet (1-1) is 0.5~3.0 mm; the planar dimensions of the sheet (1-1) are not less than 300 mm × 300 mm.

10. The hydraulic-electro-hydraulic composite forming method for thin-walled parts according to claim 6, characterized in that, In step S4, the electro-hydraulic final shaping includes one or more discharges; when multiple discharges are performed, the hydraulic pressure in the liquid chamber (200) is not removed between two adjacent discharges.

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