A magnesium alloy plate electrothermal-magnetic coupling forming device and method based on temperature field feedback and multi-stage pulse timing control

Abstract

This invention discloses a thermo-electromagnetic coupling forming device and method for magnesium alloy sheets based on temperature field feedback and multi-level pulse timing control, belonging to the field of lightweight alloy sheet forming technology. The device includes a lifting device module, a frame, a temperature detection module, a pulse heating power supply module, an electromagnetic forming module, and a control module. The temperature detection module collects the temperature Tc in the center region and the temperature Te in the edge region of the sheet in real time. The control module adjusts the pulse heating parameters according to Tc, Te, and the temperature difference ΔT, enabling the sheet to sequentially complete rapid heating, uniform heating, and heat preservation. When Tc reaches the set forming temperature T0 and ΔT is less than the set threshold ΔT0, the control module controls the lifting device to descend and triggers electromagnetic forming discharge, causing the forming coil to generate a pulsed magnetic field to drive the sheet to conform to the forming die. This solution can improve the temperature field uniformity and forming trigger accuracy of magnesium alloy sheets, reduce the risk of cracking, and improve forming stability.

Description

Technical Field

[0001] This invention belongs to the field of advanced forming technology for lightweight alloy sheets, specifically relating to an electrothermal-electromagnetic coupling forming device and method for magnesium alloy sheets based on temperature field feedback and multi-level pulse timing control. Background Technology

[0002] With the increasing demand for lightweight structural components in fields such as new energy vehicles, rail transportation, aerospace, and portable electronic equipment, magnesium alloys, due to their low density, high specific strength and stiffness, and good vibration damping performance, are gradually becoming important candidate materials for lightweight metal structural components. Magnesium alloy sheets can be used to manufacture components such as shells, covers, supports, and local load-bearing structures. However, magnesium alloys have a close-packed hexagonal crystal structure, resulting in a limited slip system that can be activated at room temperature and poor plastic deformation capacity. During conventional stamping, deep drawing, or bulging processes, problems such as cracking, wrinkling, significant springback, and insufficient dimensional accuracy are prone to occur. Therefore, improving the formability of magnesium alloy sheets and stably controlling the forming quality are important issues that need to be addressed in the engineering applications of magnesium alloy sheets.

[0003] In existing technologies, to improve the formability of magnesium alloy sheets, hot forming or warm forming methods are typically used. This involves heating the sheet to a certain temperature using a resistance furnace, heating plate, induction heating, or other external heat sources before forming. While these methods can improve the plasticity of magnesium alloys to some extent, they still have some shortcomings in practical applications: Firstly, external heating methods usually require a long heating time, resulting in low energy utilization; secondly, heat loss easily occurs during the transfer of the sheet from the heating zone to the forming zone, causing the actual forming temperature to deviate from the preset value. Furthermore, conventional heating methods have limited control over the temperature distribution in the center and edge areas of the sheet, easily leading to localized overheating or underheating, which can result in risks such as cracking, localized thinning, or incomplete forming during the forming process.

[0004] Electromagnetic forming is a high-speed forming technology that uses pulsed discharge to generate a transient strong magnetic field in a forming coil, inducing eddy currents in the metal sheet. The interaction between the eddy currents and the magnetic field generates electromagnetic force, driving the sheet to deform at high speed. Compared with traditional mechanical forming, electromagnetic forming has advantages such as non-contact loading, high forming speed, low die contact wear, and improved material forming limits. It has been researched and applied in the forming of lightweight metal sheets with good electrical conductivity, such as aluminum alloys. However, magnesium alloy sheets differ from aluminum alloys in terms of electrical conductivity, plastic deformation capacity, and temperature sensitivity. When using electromagnetic forming alone, the deformation that the sheet can withstand at room temperature is limited. The efficiency of the electromagnetic force and the final forming quality are easily limited by the material state, making it difficult to consistently meet the forming requirements of complex-shaped components.

[0005] To combine the advantages of both thermo-assisted forming and electromagnetic forming, existing technologies have proposed an electrothermal-electromagnetic composite forming approach. This involves preheating the sheet metal before electromagnetic forming to improve its plasticity, followed by high-speed forming using a pulsed magnetic field. While this technology can improve the forming performance of magnesium alloy sheets to some extent, existing devices and processes often separate or control the heating, temperature measurement, and electromagnetic forming units in stages, resulting in a lack of stable timing between the end of heating and the triggering of electromagnetic forming. If forming is triggered too early, the sheet temperature and temperature field uniformity may not yet meet requirements; if triggered too late, the sheet metal may deviate from its optimal thermoplastic state due to heat dissipation, leading to reduced forming stability.

[0006] Furthermore, existing composite forming processes often rely on preset heating times, single-point temperature measurements, or simple temperature thresholds for control, making it difficult to accurately reflect the temperature distribution in different areas of the sheet material. For magnesium alloy sheets, the heating and heat dissipation of the central and edge regions often differ. If the forming timing is determined solely based on a single temperature measurement point, problems such as insufficient or excessively high temperatures in certain areas can easily occur. Simultaneously, existing pulse heating methods are mostly continuous heating, single-stage pulse heating, or simple on / off control, making it difficult to simultaneously address the different needs of the three stages: rapid heating, temperature uniformity, and pre-forming heat preservation. This results in insufficient precision in controlling the sheet material's temperature field.

[0007] Therefore, we urgently need to design a thermo-electromagnetic coupling forming device and method for magnesium alloy plates based on temperature field feedback and multi-level pulse timing control to solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to solve the technical problems mentioned in the background art above, and to provide a magnesium alloy sheet electrothermal-electromagnetic coupling forming device and method based on temperature field feedback and multi-level pulse timing control.

[0009] The objective of this invention is achieved through the following technical solution: A magnesium alloy sheet electrothermal-electromagnetic coupling forming device based on temperature field feedback and multi-level pulse timing control includes a lifting device module, a frame, a temperature detection module, a pulse heating power supply module, an electromagnetic forming module, and a control module. The lifting device module is located above the frame and connected to the electromagnetic forming module to drive the electromagnetic forming module to move up and down. The temperature detection module is located on the frame to collect the temperature Tc in the center region and the temperature Te in the edge region of the magnesium alloy sheet. The pulse heating power supply module is electrically connected to the heating conductive copper plate in the electromagnetic forming module to apply a pulse current to the magnesium alloy sheet and generate Joule heating. The electromagnetic forming module includes a forming coil, a forming die, and a heating conductive copper plate. The magnesium alloy sheet is placed on the forming die and in contact with the heating conductive copper plate. The control module is connected to the lifting device module, the temperature detection module, the pulse heating power supply module, and the electromagnetic forming module respectively. It controls the pulse heating power supply module to perform multi-level pulse preheating according to Tc, Te, and the temperature difference ΔT. When Tc reaches the set forming temperature T0 and ΔT is less than the set threshold ΔT0, it controls the lifting device module to descend and triggers the electromagnetic forming module to discharge and form.

[0010] As a preferred embodiment of the present invention, the lifting device module includes a servo motor, a drive shaft, a deep groove ball bearing, a synchronous pulley, a flexible coupling, a rotating wheel, a synchronous belt, a lead screw nut, a motor support base, a lead screw, a connecting column, a guide column support base, a lifting device support plate, and a connecting plate. The servo motor, drive shaft, deep groove ball bearing, synchronous pulley, and flexible coupling are installed in the motor support base. The rotating wheel is fixedly connected to the lead screw nut. The synchronous pulley drives the rotating wheel and the lead screw nut to rotate through the synchronous belt, thereby driving the lead screw to lift. The connecting column is fixedly connected to the connecting plate and is used to connect the electromagnetic forming module and share the load. The guide column support base is used to limit the tilt of the lifting component.

[0011] As a preferred technical solution of the present invention, the temperature detection module includes multiple infrared thermometers, which are fixedly connected to the uprights of the frame and can measure the temperature of the central area and the edge area of ​​the magnesium alloy plate in real time by adjusting the temperature measurement angle. The control module calculates the temperature difference ΔT=Tc-Te based on the temperature Tc of the central area and the temperature Te of the edge area.

[0012] As a preferred technical solution of the present invention, the pulse heating power supply module includes a pulse power supply and a pulse power supply support. The pulse power supply support is disposed on the side of the frame, and the pulse power supply is placed on the pulse power supply support. The positive and negative electrodes of the pulse power supply are respectively connected to the heating conductive copper plate, so that the current enters the magnesium alloy plate through the heating conductive copper plate and forms a heating circuit.

[0013] As a preferred embodiment of the present invention, the multi-stage pulse preheating includes a rapid heating stage, a uniform temperature stage, and a heat preservation stage. In the rapid heating stage, the control module controls the pulse heating power supply module to output a pulse current to increase the heating rate of the magnesium alloy sheet. In the uniform temperature stage, the control module controls the pulse heating power supply module to reduce the pulse frequency and duty cycle to reduce the internal temperature gradient of the magnesium alloy sheet. In the heat preservation stage, the control module controls the pulse heating power supply module to further reduce the pulse frequency and duty cycle to keep the magnesium alloy sheet within the set forming temperature range.

[0014] As a preferred embodiment of the present invention, the electromagnetic forming module includes a busbar, connecting columns, a connecting plate, a forming coil support block, a forming coil, a forming die, a heating conductive copper plate, and a die placement platform; the connecting plate includes an upper connecting plate and a lower connecting plate, four connecting columns are fixedly connected to the upper connecting plate and the lower connecting plate respectively, the busbar is fixedly connected to the lower connecting plate, the forming coil is embedded in the forming coil support block and flush with the surface of the forming coil support block, the forming coil support block is fixedly connected to the lower connecting plate, the heating conductive copper plate is detachably mounted on the forming die, the forming die is fixed on the die placement platform, and the die placement platform is mounted on the crossbeam below the frame.

[0015] As a preferred technical solution of the present invention, the busbars are respectively connected to both ends of the forming coil. During electromagnetic forming discharge, the current flows into the forming coil from one side busbar and flows out through the other side busbar to form an electromagnetic forming discharge circuit.

[0016] This invention also provides a method for electrothermal-electromagnetic coupling forming of magnesium alloy sheets based on temperature field feedback and multi-level pulse timing control, comprising the following steps: S1. Placing the sheet: Place the magnesium alloy sheet on the forming die and make the magnesium alloy sheet contact the heated conductive copper plate. S2, Pulse Preheating: The control module starts the pulse heating power supply module, so that the pulse current enters the magnesium alloy plate through the heated conductive copper plate and generates Joule heat; S3. Temperature detection: The temperature detection module collects the temperature Tc in the center area and the temperature Te in the edge area of ​​the magnesium alloy plate in real time, and feeds Tc and Te back to the control module. S4. Closed-loop control: The control module adjusts the pulse heating parameters according to Tc, Te and temperature difference ΔT, and sequentially performs multi-stage pulse preheating, including rapid heating, uniform heating and heat preservation. S5. Triggering Forming: When Tc reaches the set forming temperature T0 and ΔT is less than the set threshold ΔT0, the control module controls the lifting device module to descend, so that the forming coil is in contact with the magnesium alloy sheet and triggers electromagnetic forming discharge, so that the forming coil generates a pulsed magnetic field, inducing eddy currents in the magnesium alloy sheet. The eddy currents and the pulsed magnetic field interact to generate electromagnetic force, driving the magnesium alloy sheet to be in contact with the forming die to complete the forming.

[0017] As a preferred technical solution of the present invention, in step S4, the multi-stage pulse preheating includes: a rapid heating stage, in which the control module controls the pulse heating power supply module to output a higher pulse frequency and a larger duty cycle to improve the heating rate of the magnesium alloy sheet; a uniform temperature stage, in which the control module controls the pulse heating power supply module to reduce the pulse frequency and duty cycle when the temperature of the magnesium alloy sheet approaches the set forming temperature T0, to reduce the internal temperature gradient of the magnesium alloy sheet; and a heat preservation stage, in which the control module controls the pulse heating power supply module to further reduce the pulse frequency and duty cycle when the temperature of the magnesium alloy sheet further approaches the set forming temperature range, so that the magnesium alloy sheet is stably maintained within the set forming temperature range.

[0018] As a preferred technical solution of the present invention, in step S5, when the control module determines that Tc reaches the set forming temperature T0 and ΔT is less than the set threshold ΔT0, it controls the lifting device module to descend within a preset time window Δt; when the forming coil reaches the forming position, the control module cuts off the pulse heating power supply module and triggers electromagnetic forming discharge; after forming is completed, the control module controls the lifting device module to rise and reset within a preset time window.

[0019] Beneficial effects: This invention integrates pulsed current heating, temperature detection, and electromagnetic forming into a single device. A control module coordinates the actions of the lifting device, pulsed heating power supply module, and electromagnetic forming module, resulting in a tighter connection between the end of sheet heating and the triggering of electromagnetic forming. Compared to separate control of heating and forming, this invention reduces waiting time and uncertainties caused by manual operation, allowing magnesium alloy sheets to be formed close to their optimal thermoplastic state, thus improving forming stability and repeatability.

[0020] This invention employs a multi-point temperature detection method for both the central and edge regions, and adjusts the pulse heating process based on the temperature difference. Through multi-stage pulse preheating involving rapid heating, uniform heating, and heat preservation, it balances heating efficiency and temperature field uniformity, reducing issues such as localized overheating, insufficient edge temperature, or excessive temperature fluctuations in the sheet material. For magnesium alloy sheets with narrow plasticity windows and poor room temperature forming capabilities, this method improves the pre-forming temperature condition, reducing the risk of cracking, wrinkling, and incomplete forming.

[0021] This invention uses a set forming temperature and temperature difference threshold as forming trigger conditions. When the center temperature of the sheet reaches the required level and the temperature difference between the center and the edge is within the allowable range, the forming coil is controlled to descend and trigger electromagnetic forming discharge. This control method does not simply rely on a preset heating time, but determines the forming timing based on the actual temperature state of the sheet, which improves process adaptability. At the same time, the coordination between the heating conductive copper plate, the forming coil, the forming die, and the lifting device is relatively compact, which is conducive to improving equipment integration, simplifying the operation process, and facilitating subsequent engineering applications. Attached Figure Description

[0022] Figure 1 This is an isometric drawing of the entire device.

[0023] Figure 2 This is the left view of the rack.

[0024] Figure 3 This is a schematic diagram of the lifting device.

[0025] Figure 4 This is a schematic diagram of the electromagnetic forming module.

[0026] Figure 5 This is a schematic diagram of the forming coil structure.

[0027] Figure 6 This is a schematic diagram of the forming die structure.

[0028] The component serial numbers and corresponding names are as follows: 1: Lifting device module; 2: Frame; 3: Temperature detection module, or infrared thermometer; 4: Pulse heating power supply module; 5: Electromagnetic forming module; 6: Control module; 41: Pulse power supply support; 51: Busbar; 52: Connecting column; 53: Connecting plate; 54: Forming coil support block; 55: Forming coil; 56: Forming die; 57: Heating conductive copper plate; 58: Die placement platform; 101: Servo motor; 102: Drive shaft; 103: Deep groove ball bearing; 104: Synchronous pulley; 105: Flexible coupling; 106: Rotary wheel; 107: Synchronous belt; 108: Lead screw nut; 109: Motor support seat; 110: Lead screw; 111: Connecting column; 112: Guide column support seat; 113: Lifting device support plate; 114: Connecting plate. Detailed Implementation

[0029] The following combination Figures 1 to 6The present invention will be further described below. The following embodiments are used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Conventional adjustments made by those skilled in the art based on the disclosure of this specification to the shape of the component, the installation method, the control parameters, or the number of temperature measuring points, as long as they do not depart from the concept of the present invention of multi-stage pulse preheating based on temperature field feedback and automatic triggering of electromagnetic forming, should all fall within the scope of protection of the present invention.

[0030] Example 1, as Figures 1 to 6 As shown, this embodiment provides a magnesium alloy sheet electrothermal-electromagnetic coupling forming device based on temperature field feedback and multi-level pulse timing control. It includes a lifting device module 1, a frame 2, a temperature detection module 3, a pulse heating power supply module 4, an electromagnetic forming module 5, and a control module 6. The lifting device module 1 is positioned above the frame 2, the electromagnetic forming module 5 is located in the internal forming area of ​​the frame 2, and the pulse heating power supply module 4 is located on the side of the frame 2. The control module 6 is connected to the lifting device module 1, the temperature detection module 3, the pulse heating power supply module 4, and the electromagnetic forming module 5, respectively, for coordinated control of sheet heating, temperature detection, lifting and positioning, and electromagnetic forming discharge. With this structure, magnesium alloy sheets can complete pulse current heating, temperature field detection, and electromagnetic forming within the same device, reducing temperature loss during sheet transfer or waiting after heating.

[0031] The lifting device module 1 includes a servo motor 101, a drive shaft 102, a deep groove ball bearing 103, a synchronous pulley 104, a flexible coupling 105, a rotating wheel 106, a synchronous belt 107, a lead screw nut 108, a motor support 109, a lead screw 110, a connecting column 111, a guide column support 112, a lifting device support plate 113, and a connecting plate 114. The servo motor 101, drive shaft 102, deep groove ball bearing 103, synchronous pulley 104, and flexible coupling 105 are mounted in the motor support 109, which is fixed to the lifting device support plate 113, which is fixed above the frame 2. The rotating wheel 106 is fixedly connected to the lead screw nut 108. The synchronous pulley 104 drives the rotating wheel 106 and the lead screw nut 108 to rotate via the synchronous belt 107. When the lead screw nut 108 rotates, it drives the lead screw 110 to perform lifting and lowering movements. The connecting column 111 is fixedly connected to the lower connecting plate 114 and connected to the electromagnetic forming module 5. It is used to transmit the lifting motion to the electromagnetic forming module 5 and to share the load during the lifting and forming process. The guide column support 112 is used to limit the tilt of the lifting component during the movement, so that the forming coil 55 maintains good posture stability and positioning accuracy during the descent.

[0032] The temperature detection module 3 includes multiple infrared thermometers, which are fixedly connected to the columns of the frame 2. The measuring angle of the infrared thermometers is adjustable, with at least one infrared thermometer pointing towards the center area of ​​the magnesium alloy sheet and at least one infrared thermometer pointing towards the edge area of ​​the magnesium alloy sheet. During operation, the temperature detection module 3 collects the temperature Tc of the center area and the temperature Te of the edge area of ​​the sheet in real time and transmits the temperature measurement signals to the control module 6. The control module 6 calculates the temperature difference ΔT=Tc-Te based on the center area temperature Tc and the edge area temperature Te to determine whether the sheet has reached the set forming temperature and whether the temperature field of the sheet meets the uniformity requirements before forming.

[0033] The pulse heating power supply module 4 includes a pulse power supply and a pulse power supply support 41. The pulse power supply support 41 is located on the side of the frame 2, and the pulse power supply is placed on the pulse power supply support 41. The positive and negative electrodes of the pulse power supply are respectively connected to the heating conductive copper plate 57 in the electromagnetic forming module 5. When the magnesium alloy sheet is placed on the forming die 56 and comes into contact with the heating conductive copper plate 57, the pulse current output by the pulse power supply enters the magnesium alloy sheet through the heating conductive copper plate 57, causing the sheet to generate Joule heat and rise in temperature. The heating conductive copper plate 57 has a detachable structure, which is convenient to replace according to the width, thickness or forming area of ​​the sheet, so that the heating contact area matches the forming action area.

[0034] The electromagnetic forming module 5 includes a busbar 51, connecting posts 52, a connecting plate 53, a forming coil support block 54, a forming coil 55, a forming die 56, a heating conductive copper plate 57, and a die placement platform 58. The connecting plate 53 includes an upper connecting plate and a lower connecting plate, and four connecting posts 52 are fixedly connected to the upper and lower connecting plates respectively. The busbar 51 is fixedly connected to the lower connecting plate. The forming coil 55 is embedded in the forming coil support block 54 and is flush with the surface of the forming coil support block 54. The forming coil support block 54 is fixedly connected to the lower connecting plate. The heating conductive copper plate 57 is disposed on the forming die 56 and is fixed by bolts or other detachable connection methods. The forming die 56 is fixed on the die placement platform 58, which is disposed on the crossbeam below the frame 2. Busbar 51 is connected to both ends of forming coil 55. During electromagnetic forming discharge, the discharge current flows into forming coil 55 from one side busbar 51, and flows out from the other side busbar 51 after passing through forming coil 55, thus forming an electromagnetic forming discharge circuit.

[0035] The control module 6 is connected to the discharge circuits of the servo motor 101, temperature detection module 3, pulse heating power supply module 4, and electromagnetic forming module 5. The temperature detection module 3 feeds back the collected central region temperature Tc and edge region temperature Te to the control module 6. Based on the difference between Tc and the set forming temperature T0, and the comparison between the temperature difference ΔT and the set threshold ΔT0, the control module 6 outputs a pulse heating control signal, a lifting control signal, and a forming discharge trigger signal. The pulse heating control signal is used to adjust the pulse frequency, pulse width, and duty cycle of the pulse heating power supply module 4; the lifting control signal is used to control the servo motor 101 to drive the lead screw 110 to lift and lower; and the forming discharge trigger signal is used to trigger the discharge circuit of the forming coil 55 to conduct when the sheet material reaches the set temperature and the temperature field uniformity meets the requirements. The discharge circuit can adopt an energy storage discharge structure commonly used in the electromagnetic forming field and is connected to the forming coil 55 via a busbar 51 to provide transient discharge current to the forming coil 55.

[0036] Example 2 illustrates a method for electrothermal-electromagnetic coupling forming of magnesium alloy sheets using the aforementioned apparatus. First, the magnesium alloy sheet to be formed is placed on the forming die 56, ensuring contact between the sheet and the heated conductive copper plate 57. The control module 6 activates the pulse heating power supply module 4, allowing pulse current to flow through the heated conductive copper plate 57 into the magnesium alloy sheet. Under the influence of the current, the sheet generates Joule heat and its temperature rises. During the heating process, the temperature detection module 3 continuously collects the temperature Tc in the center region and the temperature Te in the edge region of the sheet. The control module 6 calculates the temperature difference ΔT in real time and adjusts the pulse heating parameters based on Tc, Te, and ΔT.

[0037] In this embodiment, multi-stage pulse preheating includes a rapid heating stage, a uniform heating stage, and a holding stage. The rapid heating stage is used to bring the magnesium alloy sheet closer to the target temperature range as quickly as possible. The control module 6 controls the pulse heating power supply module 4 to output a pulse current with a higher pulse frequency and a larger duty cycle to increase the heating rate of the sheet. When the difference between Tc and the set forming temperature T0 decreases to a preset range, the control module 6 switches to the uniform heating stage, slowing down the heating rate by reducing the pulse frequency and duty cycle, and reducing the temperature difference between the center and edge areas of the sheet according to the change in ΔT. When Tc further approaches the set forming temperature T0, and ΔT gradually approaches the set threshold ΔT0, the control module 6 switches to the holding stage, further reducing the pulse frequency and duty cycle to stabilize the sheet temperature within a temperature range suitable for electromagnetic forming. The pulse frequency, pulse width, duty cycle, and switching conditions for each stage can be preset according to the grade, thickness, size, and forming requirements of the magnesium alloy sheet.

[0038] When control module 6 determines that the temperature Tc of the central region reaches the set forming temperature T0, and the temperature difference ΔT is less than the set threshold ΔT0, it indicates that the sheet material has not only reached the required forming temperature, but also that the temperature difference between the central region and the edge region is within the allowable range. At this time, control module 6 controls the lifting device module 1 to descend within the preset time window Δt, so that the forming coil 55 reaches the forming position, and cuts off the pulse heating power supply module 4 or stops its heating output. At the same time, it triggers electromagnetic forming discharge. The discharge current enters the forming coil 55 through one busbar 51 and flows out from the other busbar 51. The forming coil 55 generates a transient pulse magnetic field, inducing eddy currents in the magnesium alloy sheet. The eddy currents interact with the pulse magnetic field to generate electromagnetic force, driving the magnesium alloy sheet to deform at high speed and fit into the forming die 56. After forming is completed, control module 6 controls the lifting device module 1 to rise and reset, so that the formed part can be removed or the next forming operation can be performed.

[0039] In Example 3, based on the above examples, the number and arrangement of infrared thermometers in the temperature detection module 3 can be adjusted according to the size of the sheet material and the forming area. For sheets with a smaller width, one central temperature measuring point and two edge temperature measuring points can be used; for sheets with a larger width, more temperature measuring points can be added along the width or length of the sheet material to improve the accuracy of judging the temperature field distribution. The control module 6 can determine the edge area temperature Te based on the average, maximum, or minimum values ​​of multiple edge temperature measuring points, or it can determine the temperature difference ΔT based on the maximum temperature difference between multiple temperature measuring points, thereby adapting to the temperature measurement requirements of different sheet material sizes and different forming areas.

[0040] The forming die 56 can be replaced according to the shape of the target part. The forming coil 55 can be selected according to the size of the forming area, and is embedded in the forming coil support block 54 to ensure that the forming coil 55 can stably approach the surface of the sheet after it descends. The heating conductive copper plate 57 can be replaced according to the width of the sheet and the heating area, so that the pulse heating area corresponds to the electromagnetic action area of ​​the forming coil 55. Through the coordinated adjustment of the forming die 56, the heating conductive copper plate 57, and the forming coil 55, the same set of equipment can be used to meet the processing needs of magnesium alloy sheets of different specifications and forming parts of different shapes.

[0041] In practical applications, the forming temperature T0, temperature difference threshold ΔT0, and preset time window Δt can be determined through pre-experimentation or a process database. For magnesium alloy sheets with a narrow plastic window or large thickness, the homogenization stage or holding stage can be appropriately extended to improve the uniformity of the temperature field; for sheets with smaller thickness or faster heating, the rapid heating stage can be shortened to avoid localized overheating. Compared to methods that trigger forming only according to a fixed heating time, this embodiment determines the forming timing based on the actual temperature state of the sheet. Electromagnetic forming discharge is only triggered when the sheet reaches the set forming temperature and the temperature field uniformity meets the requirements. This reduces the impact of localized overheating, insufficient heating, and temperature fluctuations on the forming quality, and improves the stability and repeatability of the electrothermal-electromagnetic coupling forming process of magnesium alloy sheets.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A magnesium alloy sheet electrothermal-electromagnetic coupling forming device based on temperature field feedback and multi-level pulse timing control, characterized in that, The system includes a lifting device module (1), a frame (2), a temperature detection module (3), a pulse heating power supply module (4), an electromagnetic forming module (5), and a control module (6). The lifting device module (1) is located above the frame (2) and connected to the electromagnetic forming module (5) to drive the electromagnetic forming module (5) to lift. The temperature detection module (3) is located on the frame (2) and is used to collect the temperature Tc in the center area and the temperature Te in the edge area of ​​the magnesium alloy plate. The pulse heating power supply module (4) is electrically connected to the heating conductive copper plate (57) in the electromagnetic forming module (5) to apply a pulse current to the magnesium alloy plate and generate Joule heat in the magnesium alloy plate. The electromagnetic forming module (5) includes a forming coil (55), a forming die (56), and a heating conductive copper plate (57). The magnesium alloy plate is placed on the forming die (56) and in contact with the heating conductive copper plate (57). The control module (6) is connected to the lifting device module (1), the temperature detection module (3), the pulse heating power supply module (4), and the electromagnetic forming module (5) respectively. It is used to control the pulse heating power supply module (4) to perform multi-level pulse preheating according to Tc, Te and temperature difference ΔT. When Tc reaches the set forming temperature T0 and ΔT is less than the set threshold ΔT0, the lifting device module (1) is controlled to descend and trigger the electromagnetic forming module (5) to discharge and form.

2. The magnesium alloy sheet electrothermal-electromagnetic coupling forming device according to claim 1, characterized in that, The lifting device module (1) includes a servo motor (101), a drive shaft (102), a deep groove ball bearing (103), a synchronous pulley (104), a flexible coupling (105), a rotating wheel (106), a synchronous belt (107), a lead screw nut (108), a motor support (109), a lead screw (110), a connecting column (111), a guide column support (112), a lifting device support plate (113), and a connecting plate (114); the servo motor (101), drive shaft (102), and deep groove ball bearing (103) are also included. The synchronous pulley (104) and the flexible coupling (105) are installed in the motor support base (109). The rotating wheel (106) is fixedly connected to the lead screw nut (108). The synchronous pulley (104) drives the rotating wheel (106) and the lead screw nut (108) to rotate through the synchronous belt (107), thereby driving the lead screw (110) to rise and fall. The connecting column (111) is fixedly connected to the connecting plate (114) and is used to connect the electromagnetic forming module (5) and share the load. The guide column support base (112) is used to limit the tilt of the lifting component.

3. The magnesium alloy sheet electrothermal-electromagnetic coupling forming device according to claim 1, characterized in that, The temperature detection module (3) includes multiple infrared thermometers, which are fixedly connected to the columns of the frame (2) and can measure the temperature of the central area and the edge area of ​​the magnesium alloy plate in real time by adjusting the temperature measurement angle. The control module (6) calculates the temperature difference ΔT=Tc-Te based on the temperature Tc of the central area and the temperature Te of the edge area.

4. The magnesium alloy sheet electrothermal-electromagnetic coupling forming device according to claim 1, characterized in that, The pulse heating power supply module (4) includes a pulse power supply and a pulse power supply support (41). The pulse power supply support (41) is located on the side of the frame (2). The pulse power supply is placed on the pulse power supply support (41). The positive and negative electrodes of the pulse power supply are respectively connected to the heating conductive copper plate (57) so that the current enters the magnesium alloy plate through the heating conductive copper plate (57) and forms a heating circuit.

5. The electrothermal-electromagnetic coupling forming device for magnesium alloy plates according to claim 1, characterized in that, The multi-stage pulse preheating includes a rapid heating stage, a uniform temperature stage, and a heat preservation stage. In the rapid heating stage, the control module (6) controls the pulse heating power supply module (4) to output a pulse current to increase the heating rate of the magnesium alloy sheet. In the uniform temperature stage, the control module (6) controls the pulse heating power supply module (4) to reduce the pulse frequency and duty cycle to reduce the internal temperature gradient of the magnesium alloy sheet. In the heat preservation stage, the control module (6) controls the pulse heating power supply module (4) to further reduce the pulse frequency and duty cycle to keep the magnesium alloy sheet within the set forming temperature range.

6. The electrothermal-electromagnetic coupling forming device for magnesium alloy plates according to claim 1, characterized in that, The electromagnetic forming module (5) includes a busbar (51), connecting posts (52), connecting plate (53), forming coil support block (54), forming coil (55), forming die (56), heating conductive copper plate (57), and die placement platform (58). The connecting plate (53) includes an upper connecting plate and a lower connecting plate. Four connecting posts (52) are fixedly connected to the upper connecting plate and the lower connecting plate respectively. The busbar (51) is fixedly connected to the lower connecting plate. The forming coil (55) is embedded in the forming coil support block (54) and is flush with the surface of the forming coil support block (54). The forming coil support block (54) is fixedly connected to the lower connecting plate. The heating conductive copper plate (57) is detachably set on the forming die (56). The forming die (56) is fixed on the die placement platform (58). The die placement platform (58) is set on the crossbeam below the frame (2).

7. The electrothermal-electromagnetic coupling forming device for magnesium alloy plates according to claim 6, characterized in that, The busbars (51) are connected to both ends of the forming coil (55). During electromagnetic forming discharge, the current flows into the forming coil (55) from one side busbar (51) and flows out through the other side busbar (51) to form an electromagnetic forming discharge circuit.

8. A method for electrothermal-electromagnetic coupling forming of magnesium alloy sheet using the apparatus described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Placing the plate: Place the magnesium alloy plate on the forming die (56) and make the magnesium alloy plate contact the heated conductive copper plate (57). S2, Pulse preheating: The control module (6) starts the pulse heating power supply module (4), so that the pulse current enters the magnesium alloy plate through the heated conductive copper plate (57) and generates Joule heat; S3, Temperature detection: The temperature detection module (3) collects the temperature Tc in the center area and the temperature Te in the edge area of ​​the magnesium alloy plate in real time, and feeds Tc and Te back to the control module (6). S4, Closed-loop control: The control module (6) adjusts the pulse heating parameters according to Tc, Te and temperature difference ΔT, and performs multi-stage pulse preheating in sequence, including rapid heating, uniform heating and heat preservation; S5, Triggering Forming: When Tc reaches the set forming temperature T0 and ΔT is less than the set threshold ΔT0, the control module (6) controls the lifting device module (1) to descend, so that the forming coil (55) fits into the magnesium alloy plate and triggers electromagnetic forming discharge, so that the forming coil (55) generates a pulse magnetic field, which induces eddy currents in the magnesium alloy plate. The eddy currents interact with the pulse magnetic field to generate electromagnetic force, which drives the magnesium alloy plate to fit into the forming die (56) to complete the forming.

9. The electrothermal-electromagnetic coupling forming method for magnesium alloy sheets according to claim 8, characterized in that, In step S4, the multi-stage pulse preheating includes: a rapid heating stage, in which the control module (6) controls the pulse heating power supply module (4) to output a higher pulse frequency and a larger duty cycle to increase the heating rate of the magnesium alloy sheet; a uniform temperature stage, in which the control module (6) controls the pulse heating power supply module (4) to reduce the pulse frequency and duty cycle when the temperature of the magnesium alloy sheet approaches the set forming temperature T0, so as to reduce the internal temperature gradient of the magnesium alloy sheet; and a heat preservation stage, in which the control module (6) controls the pulse heating power supply module (4) to further reduce the pulse frequency and duty cycle when the temperature of the magnesium alloy sheet approaches the set forming temperature range, so as to keep the magnesium alloy sheet stably within the set forming temperature range.

10. The method for electrothermal-electromagnetic coupling forming of magnesium alloy sheet according to claim 8, characterized in that, In step S5, when the control module (6) determines that Tc reaches the set forming temperature T0 and ΔT is less than the set threshold ΔT0, it controls the lifting device module (1) to descend within the preset time window Δt; when the forming coil (55) reaches the forming position, the control module (6) cuts off the pulse heating power supply module (4) and triggers electromagnetic forming discharge; after forming is completed, the control module (6) controls the lifting device module (1) to rise and reset within the preset time window.

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