Radial-axial two-way loading type plate forming method driven by pulse electromagnetic force

Abstract

The invention belongs to the field of electromagnetic forming and manufacturing of workpieces, discloses a radial-axial two-way loading type plate forming method driven by pulse electromagnetic force, and aims to solve the technical problem of non-uniform deformation of workpieces in traditional electromagnetic forming. A hydraulic two-way pressing die is adopted to be matched with a female die to apply radial pressure and axial pressure to a plate at the same time in the plate forming process, the hydraulic two-way pressing die comprises a piston, an inner hydraulic cavity and an outer hydraulic cavity, the inner hydraulic cavity and the outer hydraulic cavity are communicated, and hydraulic media of the inner hydraulic cavity and the outer hydraulic cavity are pushed by the piston to apply the axial pressure and the radial pressure to the plate respectively; the piston comprises a conductor layer, axial electromagnetic force is formed under the action of an electromagnetic field generated by the driving coil, the piston is driven to move, and dynamic pressure waves are formed. Pressure waves simultaneously generate axial pressure and radial pressure on the plate through the inner hydraulic cavity and the outer hydraulic cavity. According to the method, the forming uniformity of the workpiece is remarkably improved, and a brand new solution is provided for scientific research and industrial application in the field of electromagnetic forming of the workpiece.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic forming manufacturing of workpieces, and in particular relates to a radial-axial bidirectional loading plate forming method driven by pulse electromagnetic force. Background Art

[0002] Currently, electromagnetic forming technology is widely used in the processing and manufacturing of sheet metal and pipe fittings, but existing technologies still face numerous technical bottlenecks in practical application. Traditional electromagnetic forming processes for sheet metal often rely on unidirectional pressure application, which is prone to uneven radial deformation and uneven stress distribution in localized areas of the workpiece. In the pipe forming process, the uneven axial force distribution makes it difficult to achieve the desired forming results and product dimensional accuracy that meet high-end manufacturing requirements.

[0003] Because the energy transfer method in the forming process mainly relies on the eddy currents induced inside the workpiece, a single electromagnetic force field is difficult to achieve balanced pressurization, and the uncertainty of workpiece deformation is large, which limits the stability and repeatability of the process.

[0004] In recent years, pulsed electromagnetic forming technology has gradually entered the industrial application field. Its core is to use high-energy pulse current to stimulate the workpiece to generate eddy currents within the drive coil, thereby generating instantaneous high voltage. However, relying solely on the induction effect within the workpiece itself is often unable to overcome the defects caused by localized uneven force. Summary of the Invention

[0005] The present invention addresses these challenges by providing a pulsed electromagnetic force-driven radial-axial bidirectional loading plate forming method. By optimizing the design of the conductor, blank holder, die, and enclosed liquid, balanced radial and axial pressure is simultaneously applied to the workpiece during the forming process. Utilizing the principle of bidirectional loading, this method reduces deformation in the center of the plate or tube while improving overall forming uniformity, thereby enhancing processing precision and finished product quality.

[0006] In order to achieve the above object, the technical solution provided by the present invention is: A radial-axial bidirectional loading sheet metal forming method driven by pulsed electromagnetic force adopts a hydraulic bidirectional pressing die to cooperate with a die to simultaneously apply radial and axial pressure to the sheet metal during the sheet metal forming process. The hydraulic bidirectional pressing die includes a piston and a connected inner hydraulic chamber and an outer hydraulic chamber. The hydraulic medium in the inner and outer hydraulic chambers applies axial and radial pressure to the sheet metal respectively under the push of the piston; the piston includes a conductor layer, which forms an axial electromagnetic force under the action of the electromagnetic field generated by the driving coil, driving the piston to move axially.

[0007] The plate forming method comprises the following steps: Step 1: Select the die according to the sheet metal forming specifications, determine the size parameters of the drive coil and the hydraulic two-way pressing die, and manufacture the drive coil and the hydraulic two-way pressing die; Step 2: Place the plate to be formed and the hydraulic two-way pressing die coaxially on the axis of the die, and fix the edge of the plate; Step 3: After injecting hydraulic medium into the inner and outer hydraulic chambers, insert the piston to exhaust the air in the inner and outer hydraulic chambers, so that the piston presses the plate to be formed through the hydraulic medium; Step 4: A driving coil is coaxially arranged above the piston and electrically connected to the pulse power supply via a discharge switch; Step 5: Close the discharge switch to power the drive coil, generating a transient pulse magnetic field, which forms an axial electromagnetic force in the conductor layer of the piston. Under the action of the electromagnetic force, the piston moves axially at high speed, pushing the hydraulic medium to form a dynamic pressure wave; Step 6: The pressure wave generates axial and radial pressure on the plate through the inner and outer hydraulic chambers, driving the plate to fit the die to complete the forming.

[0008] Preferably, in step 1, a plate electromagnetic forming simulation model including a driving coil, a hydraulic two-way die, a plate and a die is constructed using finite element software, a pulse current is applied to the driving coil in the plate electromagnetic forming simulation model, the forming effect of the plate is simulated, and compared with the plate forming specifications, the parameters of the driving coil and the dimensional parameters of the hydraulic two-way die are repeatedly adjusted to obtain the optimal parameters of the driving coil and the dimensional parameters of the hydraulic two-way die.

[0009] Preferably, the conductor layer of the piston is made of copper.

[0010] Preferably, the pulse power supply is a capacitive power supply.

[0011] Preferably, the piston further comprises a sealing layer fixedly connected to the conductor layer, wherein the sealing layer is used for sealing and generating pressure on the hydraulic medium in the inner and outer hydraulic chambers under the pushing action of the conductor layer.

[0012] The apparatus for the radial-axial bidirectional loading plate forming method comprises a die, a hydraulic bidirectional die drive coil, and a pulse power supply. The hydraulic bidirectional die comprises a piston and interconnected inner and outer hydraulic cavities. The drive coil is electrically connected to the pulse power supply via a discharge switch. After placing the plate to be formed between the die and the hydraulic two-way pressing die, hydraulic medium is injected into the inner hydraulic cavity and the outer hydraulic cavity. The hydraulic medium applies axial and radial pressure to the plate to be formed respectively under the push of the piston.

[0013] Preferably, the piston comprises a conductor layer and a sealing layer, and the conductor layer is provided on a side of the piston close to the driving coil.

[0014] Preferably, a plurality of radial through holes distributed at equal angles are provided between the inner hydraulic cavity and the outer hydraulic cavity of the hydraulic bidirectional die, and the outer hydraulic cavity is connected to the inner hydraulic cavity via the through holes.

[0015] Preferably, the number of the through holes is 3.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1) The forming uniformity of the workpiece is significantly improved; This invention utilizes a bidirectional loading design, transmitting pulsed electromagnetic force to various areas of the workpiece through auxiliary conductors and a confined liquid, effectively compensating for the localized stress concentration associated with traditional unidirectional loading. During the loading process, radial and axial pressure are evenly distributed across the workpiece, achieving balanced deformation across the entire workpiece and ensuring stable and consistent forming quality.

[0017] 2) High efficiency of energy conversion and transmission; This invention incorporates an auxiliary conductor within the drive coil. Through a precisely designed conductor piston (comprising copper and steel layers), high-speed motion induces eddy currents that synergize with the eddy currents within the workpiece, achieving efficient energy conversion. The pulsed electromagnetic force is rapidly transmitted to the enclosed liquid, where it is converted into balanced mechanical pressure, maximizing energy utilization and minimizing energy consumption.

[0018] 3) Strong process stability and repeatability; Through precise matching of the blank holder die, die, sealing fluid, and key structural parameters (such as radius, thickness, and blank holder height), stable loading is ensured throughout the multiple forming processes. The overall design of the workpiece forming device offers high interference and error tolerance, resulting in highly repeatable forming processes suitable for high-volume production.

[0019] 4) Excellent process safety and environmental adaptability; The use of closed liquid as the energy transfer medium avoids wear and local high temperature problems that may be caused by direct metal contact, while reducing processing noise and vibration, and improving the safety of equipment operation and environmental adaptability.

[0020] 5) Wide applicability and high processing precision; By applying radial force to the side edges of the sheet metal, the present invention converts the tensile stress state during sheet metal forming into a compressive stress state, thereby significantly improving the sheet metal forming effect and the quality of the formed sheet metal. In addition to sheet metal forming, the present invention's method is also applicable to the precision machining of pipes and other curved workpieces. By utilizing bidirectional balanced loading, it not only effectively controls deformation at the edges and center of the workpiece, but also meets the stringent requirements for uniformity and precision in forming workpieces of varying sizes and shapes, providing powerful technical support for the field of high-end manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings.

[0022] Figure 1 Schematic diagram of the structure of a plate forming device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] like Figure 1 As shown, the pulse electromagnetic force driven radial-axial bidirectional loading plate forming method includes: Step 1: Select the die according to the sheet metal forming specifications, determine the size parameters of the drive coil and the hydraulic two-way pressing die, and manufacture the drive coil and the hydraulic two-way pressing die.

[0024] The finite element software COMSOL Multiphysics is used to construct a sheet metal electromagnetic forming simulation model including a driving coil, a hydraulic two-way die, a sheet metal and a die. A pulse current is applied to the driving coil in the sheet metal electromagnetic forming simulation model to simulate the forming effect of the sheet metal. Compared with the sheet metal forming specifications, the parameters of the driving coil and the dimensional parameters of the hydraulic two-way die are repeatedly adjusted to obtain the optimal parameters of the driving coil and the dimensional parameters of the hydraulic two-way die.

[0025] Step 2: Place the plate to be formed and the hydraulic two-way pressing die coaxially on the axis of the die, and fix the edges of the plate.

[0026] Step 3: After injecting hydraulic medium into the inner and outer hydraulic cavities, insert the piston to discharge the air in the inner and outer hydraulic cavities, so that the piston presses the plate to be formed through the hydraulic medium.

[0027] Step 4: A driving coil is coaxially arranged above the piston and electrically connected to the pulse power supply via a discharge switch.

[0028] Step 5: Close the discharge switch to power the drive coil, generate an instantaneous pulse magnetic field, and form an axial electromagnetic force in the conductor layer of the piston. Under the action of the electromagnetic force, the piston moves axially, pushing the hydraulic medium to form a dynamic pressure wave.

[0029] Step 6: The pressure wave generates axial and radial pressure on the plate through the inner hydraulic chamber and the outer hydraulic chamber, driving the plate to be formed to fit the die for bulging processing, disconnecting the discharge switch to determine whether the plate meets the plate forming specifications. If so, the process ends. If not, repeat steps 5-6 and bulge the plate again.

[0030] The device of the above-mentioned radial-axial bidirectional loading plate forming method includes a die 1, a hydraulic bidirectional pressing die 3, a driving coil 6 and a pulse power supply. The hydraulic bidirectional pressing die 3 includes a piston 301 and a connected internal hydraulic chamber 302 and an external hydraulic chamber 303. The driving coil is electrically connected to the pulse power supply via a discharge switch 7.

[0031] After the plate 2 to be formed is placed between the die 1 and the hydraulic two-way pressing die 3, hydraulic medium 4 is injected into the inner hydraulic cavity and the outer hydraulic cavity. The hydraulic medium exerts axial pressure Fa and radial pressure Fr on the plate to be formed respectively under the push of the piston.

[0032] The piston 301 includes a conductor layer 3011 and a sealing layer 3012. The conductor layer is arranged on the side of the piston close to the driving coil. The conductor layer is made of copper and the sealing layer is made of steel.

[0033] A plurality of radial through holes are provided between the inner hydraulic cavity and the outer hydraulic cavity of the hydraulic bidirectional die at equal angles, and the outer hydraulic cavity is connected to the inner hydraulic cavity through the through holes. In the embodiment, the number of radial through holes is three.

[0034] The radius Rb of the plate to be formed is greater than the radius Rd of the piston and satisfies: R ynn <Rb<R yny <R yyy ; R ynn — Rd ≈ 0; Where R ynn Indicates the radius of the hydraulic cavity of the hydraulic two-way die, R yny Indicates the inner diameter of the outer hydraulic cavity of the hydraulic bidirectional die, R yyy Indicates the outer diameter of the hydraulic double-acting die.

[0035] The height hyn of the outer hydraulic cavity of the hydraulic two-way pressing die is less than the height hyy of the hydraulic two-way pressing die and satisfies: hyn + hb <hyy; Where hb represents the thickness of the plate.

[0036] The pulse power supply is a capacitor power supply, the capacitance of the capacitor power supply is 480F, and the voltage of the capacitor power supply is 6.02kV.

[0037] Implementation results demonstrate that the method provided by this invention shifts the tensile stress state during sheet forming to a compressive state, significantly improving the sheet forming effect and quality. It also achieves balanced overall sheet deformation and resolves the localized stress concentration issues associated with traditional unidirectional sheet bulging methods. The forming device exhibits minimal vibration during the forming process, eliminating the high noise levels associated with traditional metal workpiece processing.

[0038] In addition to the bulging processing of plate parts, the method of the present invention is also applicable to the precision processing of pipe parts and other curved surface workpieces.

[0039] The present invention not only realizes efficient utilization of energy transfer, but also provides a practical new process for industrial applications in the field of electromagnetic forming.

Claims

1. A radial-axial bidirectional loading plate forming method driven by pulse electromagnetic force, characterized in that: A hydraulic bidirectional die is used to simultaneously apply radial and axial pressure to the sheet metal during the sheet metal forming process in conjunction with a die. The die comprises a piston and interconnected inner and outer hydraulic chambers. The hydraulic media in the inner and outer hydraulic chambers, pushed by the piston, apply axial and radial pressure to the sheet metal, respectively. The piston comprises a conductor layer, which generates an axial electromagnetic force under the action of the electromagnetic field generated by a drive coil, driving the piston to move axially. The following steps are involved: Step 1: Select the die according to the sheet metal forming specifications, determine the size parameters of the drive coil and the hydraulic two-way pressing die, and manufacture the drive coil and the hydraulic two-way pressing die; Step 2: Place the plate to be formed and the hydraulic two-way pressing die coaxially on the axis of the die, and fix the edge of the plate; Step 3: After injecting hydraulic medium into the inner and outer hydraulic chambers, insert the piston to exhaust the air in the inner and outer hydraulic chambers, so that the piston presses the plate to be formed through the hydraulic medium; Step 4: A driving coil is coaxially arranged above the piston and electrically connected to the pulse power supply via a discharge switch; Step 5: Close the discharge switch to power the drive coil, generating a transient pulse magnetic field, which forms an axial electromagnetic force in the conductor layer of the piston. The piston moves axially under the action of the electromagnetic force, pushing the hydraulic medium to form a dynamic pressure wave; Step 6: The pressure wave generates axial and radial pressure on the plate through the inner and outer hydraulic cavities, driving the plate to fit the die to complete the forming.

2. The pulse electromagnetic force driven radial-axial bidirectional loading plate forming method according to claim 1, characterized in that: In step 1, a plate electromagnetic forming simulation model including a driving coil, a hydraulic two-way die, a plate and a die is constructed using finite element software, a pulse current is applied to the driving coil in the plate electromagnetic forming simulation model, and the forming effect of the plate is simulated and compared with the plate forming specifications, and the parameters of the driving coil and the dimensional parameters of the hydraulic two-way die are repeatedly adjusted to obtain the optimal parameters of the driving coil and the dimensional parameters of the hydraulic two-way die.

3. The pulse electromagnetic force driven radial-axial bidirectional loading plate forming method according to claim 1, characterized in that: The conductor layer of the piston is made of copper material.

4. The pulse electromagnetic force driven radial-axial bidirectional loading plate forming method according to claim 1, characterized in that: In step 4, the pulse power supply is a capacitor power supply.

5. The pulse electromagnetic force driven radial-axial bidirectional loading plate forming method according to claim 1, characterized in that: The piston further comprises a sealing layer fixedly connected to the conductor layer, wherein the sealing layer is used for sealing and generating pressure on the hydraulic medium in the inner hydraulic cavity and the outer hydraulic cavity under the pushing action of the conductor layer.

6. The apparatus for the radial-axial bidirectional loading plate forming method driven by pulse electromagnetic force according to any one of claims 1 to 5, characterized in that: The invention comprises a die (1), a hydraulic two-way pressing die (3), a driving coil (6) and a pulse power supply (8), wherein the hydraulic two-way pressing die (3) comprises a piston (301) and an inner hydraulic cavity (302) and an outer hydraulic cavity (303) that are connected to each other, and the driving coil is electrically connected to the pulse power supply via a discharge switch (7); After a plate to be formed (2) is placed between the die (1) and the hydraulic two-way pressing die (3), a hydraulic medium (4) is injected into the inner hydraulic cavity and the outer hydraulic cavity. The hydraulic medium applies axial and radial pressures to the plate to be formed respectively under the push of the piston.

7. The device according to claim 6, characterized in that The piston (301) comprises a conductor layer (3011) and a sealing layer (3012), wherein the conductor layer is arranged on a side of the piston close to the driving coil.

8. The device according to claim 6, characterized in that The radius Rb of the sheet to be formed is greater than the radius Rd of the piston.

9. The device according to claim 6, characterized in that A plurality of radial through holes (304) distributed at equal angles are provided between the inner hydraulic cavity and the outer hydraulic cavity of the hydraulic bidirectional pressing die, and the outer hydraulic cavity is connected to the inner hydraulic cavity via the through holes.

10. The device according to claim 9, characterized in that The number of the radial through holes is 3.

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