Sheet metal array microstructure electromagnetic forming device and method

Abstract

The application discloses a metal sheet array microstructure electromagnetic forming device and an electromagnetic forming method thereof, which comprises a forming coil, a current collecting device, an array microstructure die, a pulse power source, and the upper part of the current collecting device is an annular part, the lower part is a left and right arranged side U-shaped structure, the forming coil is arranged in the annular part and is positioned through a reinforcing device, the array microstructure die is provided with array microstructure characteristics on at least one side, a sheet blank is arranged on one side of the array microstructure characteristics, and the sheet blank is inserted into the side U-shaped structure of the lower part of the current collecting device and is in contact with the current collecting device. During forming, the forming coil is electrified, a strong instantaneous pulse current is induced in the current collecting device by the forming coil, and when the induced current flows through the sheet blank and a metal plate, strong attraction is generated between the sheet blank and the metal plate to form the sheet blank and the metal plate. The application has reasonable structure, good forming effect and high precision, and can solve the problems of easy damage of a guide frame type uniform pressure coil in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of metal plastic processing and forming technology, and relates to an electromagnetic forming device and method for metal thin plate array microstructures. Background Technology

[0002] Thin-walled array microstructure components are widely used in new energy, nuclear energy, and chemical industries. These components generally require a large aspect ratio to function effectively and high surface accuracy for subsequent assembly. Taking fuel cell metal bipolar plates as an example, their flow channel width is typically less than 1 mm, their depth greater than 0.5 mm, and their surface accuracy deviation less than 1%. Traditional steel die stamping easily leads to excessive thinning and cracking at the rounded corners, and significant unloading springback results in low surface accuracy of the bipolar plates. Therefore, exploring new forming processes for thin-walled array microstructure components is urgent and of great significance.

[0003] Electromagnetic forming is a high-strain-rate forming method that utilizes the strong Lorentz force exerted on a current-carrying conductor in a magnetic field to cause it to move at high speed and take shape. It can effectively improve the formability of sheet metal and reduce unloading springback, and is particularly suitable for forming thin, difficult-to-deform metal sheets such as stainless steel, titanium alloys, and aluminum alloys. For electromagnetic forming processes of array microstructure parts, the uniformity of magnetic pressure is crucial.

[0004] A search revealed an article titled "Study on Uniform Pressure Coil and Sheet Force in Electromagnetic Forming of Flat Plates," published in the *Journal of Huazhong University of Science and Technology (Natural Science Edition)*, Volume 39, Issue 2, February 2011. This article introduces a uniform pressure coil that can generate relatively uniform magnetic pressure, achieving high-quality forming of thin metal sheets. Additionally, Chinese invention patent CN 111558646 A, "An Electromagnetic Manufacturing Method and Forming Device for Mesoscopic-Scale Sheets," employs an embedded method to achieve the generation of uniform magnetic pressure and the electromagnetic forming of arrayed microstructure parts. However, the uniform pressure coil used in these electromagnetic forming methods for thin metal sheets is a frame-type coil, mainly consisting of a three-dimensional spiral coil and an outer frame, encapsulated with epoxy resin. However, the epoxy resin used for potting is prone to cracking under the strong impact force during electromagnetic molding, resulting in a low coil life. Secondly, this type of coil is generally processed by wire cutting, and in order to ensure the insulation effect, there are large gaps between each coil turn, resulting in low energy density and insufficient forming ability. Finally, the size of the array microstructure parts is severely limited by the coil size, and machining large conductor frame coils is expensive and difficult, resulting in the small area of ​​the thin plate parts produced by this solution, which is difficult to meet the requirements of large-scale commercial use. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide an electromagnetic forming device for microstructures of metal sheet array with reasonable structural design and good forming effect, which can effectively solve the problems of easy damage of the guide frame uniform pressure coil, low energy density and the serious limitation of part size on the size of the guide frame uniform pressure coil in the prior art.

[0006] The second technical problem to be solved by the present invention is to provide an electromagnetic forming method for metal sheet array microstructures, which uses a special electromagnetic forming device for forming and has the characteristics of convenient operation and good forming effect.

[0007] The technical solution adopted by the present invention to solve the first technical problem mentioned above is as follows: an electromagnetic forming device for metal sheet array microstructure, characterized in that: it includes a forming coil, a current collector, an array microstructure mold, and a pulse power supply for supplying power to the forming coil; the upper part of the current collector is an annular part, and the lower part is a U-shaped structure arranged on the left and right sides; the forming coil is arranged in the annular part of the current collector and positioned by a reinforcing device; at least one side of the upper and lower sides of the array microstructure mold has array microstructure features; the sheet blank is arranged on the side of the array microstructure mold with array microstructure features; the left and right ends of the sheet blank and the array microstructure mold are respectively inserted into the lower side U-shaped structure of the current collector and in contact with the current collector, and are pressed and fixed by an external pressing device.

[0008] As an improvement, the shaped coil is composed of a wire and a coil frame, with the wire tightly wound around the coil frame in a spiral shape, and the pulse power supply electrically connected to the wire.

[0009] Furthermore, the reinforcing device is an annular sleeve that mates with the annular portion of the current collector. The reinforcing device covers the annular portion of the current collector and is coaxially assembled with the annular portion of the current collector and the forming coil.

[0010] Furthermore, the lower end of the upper annular portion of the current collection device is open, and the opening extends downward and to both sides to connect with the rear end of the lower side U-shaped structure. The left and right sides of the array microstructure mold are provided with mold fixing plates, and both ends of the mold fixing plates and the thin plate blank are set in the side U-shaped structure and fixed by the pressing device.

[0011] Furthermore, the upper and lower sides of the array microstructure mold have array microstructure features, the thin plate blank is set on one side of the array microstructure features, the other side of the array microstructure mold is provided with a current-carrying plate, the two ends of the current-carrying plate are in contact with the current collection device, and an insulating plate is provided between the current-carrying plate and the array microstructure mold.

[0012] Furthermore, the current-carrying plate is made of pure copper, pure aluminum, copper alloy, or aluminum alloy.

[0013] Furthermore, the array microstructure mold has array microstructure features on both the upper and lower sides, and thin plate blanks are provided on both the upper and lower sides of the array microstructure mold.

[0014] Furthermore, when the thin plate blank is made of titanium alloy, stainless steel or other materials with low conductivity and high strength, a driving plate is also provided on the outside of the thin plate blank. The driving plate is made of pure aluminum, pure copper, aluminum alloy or copper alloy. The left and right ends of the driving plate are also inserted into the lower side U-shaped structure of the current collection device and contact the current collection device, and are pressed and fixed by the pressing device.

[0015] Finally, insulating blocks are provided between the left and right ends of the array microstructure mold and the mold fixing plate.

[0016] The technical solution adopted by this invention to solve the second technical problem mentioned above is: an electromagnetic forming method for metal thin plate array microstructures, characterized in that: the forming is performed using the aforementioned electromagnetic forming device, and the specific steps are as follows:

[0017] 1) Determine the size and parameters of the array microstructure mold, current carrier plate, and current collection device according to the specifications of the metal sheet microstructure array to be formed;

[0018] 2) Based on the size and parameters of the array microstructure mold, current carrier plate and current collector obtained in step 1), fabricate the array microstructure mold and current collector;

[0019] 3) Determine whether a drive board is needed based on the material of the microstructure array of the metal sheet to be formed;

[0020] 4) Determine the discharge parameters based on the material and microstructure characteristics of the metal sheet microstructure array to be formed; typically, the discharge capacitance is 20~500 μF and the discharge voltage is 5~20 kV.

[0021] 5) Place the thin plate blank or current-carrying plate to be formed on the upper and lower sides of the array microstructure mold, and fit the side U-shaped structure of the lower part of the current collection device on the left and right ends of the array microstructure mold. The current collection device is in contact with the thin plate blank or current-carrying plate.

[0022] 6) Use an edge-pressing device to press the sheet material to be formed;

[0023] 7) Turn on the pulse power supply to energize the forming coil and begin forming;

[0024] 8) After forming is completed, remove the edge pressing device and take out the formed sheet.

[0025] Compared with the prior art, the advantages of the present invention are as follows:

[0026] The electromagnetic forming apparatus includes a pulse power supply, a forming coil, a current collector, a reinforcement device, an array microstructure mold, a mold fixing plate, a pressure plate, and an insulating block. The size of the apparatus is manufactured according to the specifications of the microstructure array of the metal sheet to be formed. A strong instantaneous pulse current is induced in the current collector by the forming coil. When the induced current flows through the sheet blank and the current-carrying plate, they generate a strong attraction, thus forming the sheet. The electromagnetic forming apparatus of this invention has a reasonable structural design and can effectively solve the problems of easy damage to the guide frame type uniform pressure coil, low energy density, and the severe limitation of part size on the size of the guide frame type uniform pressure coil in the prior art. The forming method of this invention has good forming effect and high precision, and can meet the requirements of large-scale commercial use. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the electromagnetic forming device for metal sheet array microstructures according to Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of the microstructure feature dimensions in Example 1;

[0029] Figure 3 This is a schematic diagram of the lower half of the electromagnetic forming device for metal sheet array microstructures according to Embodiment 2 of the present invention;

[0030] Figure 4 This is a schematic diagram of the lower half of the electromagnetic forming device for metal sheet array microstructures according to Embodiment 3 of the present invention. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0032] Example 1

[0033] like Figure 1 As shown, an electromagnetic forming device for a metal sheet array microstructure includes a forming coil 2, a current collector 1, an array microstructure mold 3, and a pulse power supply 4 for supplying power to the forming coil 2. The current collector 1 has an upper annular portion 11 and a lower U-shaped structure 12 arranged on the left and right sides. The forming coil 2 consists of a wire 22 and a coil frame 21. The wire 22 is tightly wound around the coil frame 21 in a spiral form. The pulse power supply 4 is electrically connected to the wire 22. The forming coil 2 is disposed within the annular portion 11 of the current collector 1 and positioned by a reinforcing device 10. The reinforcing device 10 is a circular annular sleeve that mates with the annular portion 11 of the current collector 1. The reinforcing device 10 covers the annular portion 11 of the current collector 1 and is coaxially assembled with the annular portion 11 and the forming coil 2. The function of the reinforcing device 10 is to improve the strength of the current collector 1 and prevent the current collector 1 from deforming under the Lorentz force applied by the forming coil 2.

[0034] At least one side of the upper and lower sides of the array microstructure mold 3 has array microstructure features. The thin plate blank 6 is made of aluminum alloy with a thickness of 0.1 mm and is disposed on the side of the array microstructure mold 3 with array microstructure features. In this embodiment, the upper side of the array microstructure mold 3 has array microstructure features, and the thin plate blank 6 is disposed on the upper side of the array microstructure mold 3. A current-carrying plate 7 is provided on the lower side of the array microstructure mold 3, and an insulating plate 8 is provided between the current-carrying plate 7 and the array microstructure mold 3. The two ends of the thin plate blank 6 and the current-carrying plate 7 are in contact with the current collecting device 1.

[0035] The lower end of the upper annular portion 11 of the current collection device 1 is open, and the opening extends downward and to both sides to connect with the rear end of the lower side U-shaped structure 12. The left and right sides of the array microstructure mold 3 are provided with mold fixing plates 30. The mold fixing plates 30, the thin plate blank 6, the current carrying plate 7 and the left and right ends of the array microstructure mold 3 are respectively inserted into the lower side U-shaped structure 12 of the current collection device 1 and are pressed and fixed by the external pressing device 5.

[0036] The current-carrying plate 7 is made of pure copper, pure aluminum, copper alloy, or aluminum alloy. In this embodiment, the current-carrying plate 7 is made of aluminum alloy with a thickness of 1 mm. Insulating blocks 80 are provided between the left and right ends of the array microstructure mold 3 and the mold fixing plate 30 to prevent induced current from flowing through the mold.

[0037] An electromagnetic forming method for a metal sheet array microstructure utilizes the aforementioned electromagnetic forming apparatus. A strong instantaneous pulse current is induced in the current collector 1 by the forming coil 2. When the induced current flows through the sheet blank 6 and the current-carrying plate 7, they generate a strong attractive force, resulting in the forming process. The method specifically includes the following steps:

[0038] 1. Based on the specifications of the microstructure array of the metal sheet to be formed, determine the size and parameters of the array microstructure mold 3 and the flow collector 1; here, the mold microstructure is a semi-circular flow channel array, with each flow channel being 1mm wide and 0.5mm high, such as... Figure 2 As shown, the array area is 100 mm × 100 mm;

[0039] 2. Based on the size and parameters of the array microstructure mold 3, current carrier plate 7 and current collector 1 obtained in step one, fabricate the array microstructure mold 3 and current collector 1.

[0040] 3. Determine whether a driving board is needed based on the material of the microstructure array of the metal sheet to be formed; in this case, the material is aluminum alloy with a thickness of 0.1 mm, so a driving board is not needed.

[0041] IV. Based on the material and microstructure characteristics of the metal sheet microstructure array to be formed, determine the discharge parameters; here, the discharge parameters are determined to be a capacitance of 100 μF and a voltage of 8 kV.

[0042] 5. Place the thin plate blank 6 and the current-carrying plate 7 on the upper and lower sides of the array microstructure mold 3, and fit the side U-shaped structure 12 of the lower part of the current collection device 1 on the left and right ends of the array microstructure mold 3. The current collection device 1 is in contact with the thin plate blank 6 and the current-carrying plate 7.

[0043] 6. The sheet material to be formed is pressed tightly using the edge pressing device 5;

[0044] 7. Energize forming coil 2 to begin forming;

[0045] 8. After forming is completed, remove the edge pressing device 5 and take out the formed sheet.

[0046] This forming device and method has a higher energy density than the traditional guide frame electromagnetic forming method. It can form metal thin plate array microstructures at a lower voltage, and the formed thin plate array microstructures are larger in size, which can be successfully commercialized.

[0047] Example 2

[0048] like Figure 3 As shown, an electromagnetic forming device for metal sheet array microstructures differs from Embodiment 1 in that: the array microstructure mold 3 has array microstructure features on both its upper and lower sides; correspondingly, no insulating plates are provided on either side of the array microstructure mold 3; and thin sheet blanks 6 are provided on both sides of the array microstructure mold 3. Other structures are the same as in Embodiment 1. After the pulse power supply 4 discharges, a strong current in the same direction is generated in the thin sheet blanks 6 on both sides, thus creating a strong mutual attraction between them, causing them to move at high speed towards the mold for forming.

[0049] In this embodiment, the thin plate blank 6 is made of magnesium alloy with a thickness of 0.1 mm. The number of mold microstructure dimensions and array area are the same as in Embodiment 1. In this embodiment, the discharge capacitor is 100 μF and the discharge voltage is 9 kV. Therefore, this embodiment can realize electromagnetic forming of two thin plate microarray microstructures, greatly improving the forming efficiency.

[0050] Example 3

[0051] like Figure 3 As shown, a metal sheet array microstructure electromagnetic forming device differs from Embodiment 2 in that: a driving plate 9 is also provided on the outer side of the sheet blank 6. The driving plate 9 is made of pure aluminum, pure copper, aluminum alloy, or copper alloy. The left and right ends of the driving plate 9 are also inserted into the lower side U-shaped structure 12 of the current collecting device 1 and contact the current collecting device 1, and are fixed by the external pressing device 5. Other structures are the same as in Embodiment 2.

[0052] In this embodiment, the sheet metal blank 6 is made of titanium alloy with a thickness of 0.1 mm; the drive plate 9 is made of aluminum alloy with a thickness of 0.3 mm. Because titanium alloy has low conductivity and high strength, it is difficult to form the sheet metal using only the Lorentz force it generates. Therefore, the aluminum alloy drive plate 9, with its high conductivity and low strength, can drive the titanium alloy sheet metal to be formed at high speed. In addition, in this embodiment, the discharge capacitor is 100 μF and the discharge voltage is 11 kV.

[0053] Comparing the sheet material formed in this embodiment with the sheet material formed by the prior art, it is shown that the forming method of the present invention has better effect and higher precision.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electromagnetic forming device for a metal thin plate array microstructure, characterized in that: The device includes a forming coil, a current collector, an array microstructure mold, and a pulse power supply for supplying power to the forming coil. The upper part of the current collector is an annular part, and the lower part is a U-shaped structure arranged on the left and right sides. The forming coil is set in the annular part of the current collector and positioned by a reinforcing device. At least one side of the upper and lower sides of the array microstructure mold has array microstructure features. The thin plate blank is set on the side of the array microstructure mold with array microstructure features. The left and right ends of the thin plate blank and the array microstructure mold are respectively inserted into the lower side U-shaped structure of the current collector and contact the current collector, and are pressed and fixed by an external pressing device. The formed coil is composed of wires and a coil frame. The wires are tightly wound on the coil frame in a spiral shape, and the pulse power supply is electrically connected to the wires. The reinforcing device is a circular annular sleeve that mates with the annular portion of the current collector. The reinforcing device covers the annular portion of the current collector and is coaxially assembled with the annular portion and the forming coil. The lower end of the upper annular part of the current collection device is open, and the opening extends downward and to both sides to connect with the rear end of the lower side U-shaped structure. The left and right sides of the array microstructure mold are provided with mold fixing plates. The mold fixing plates and both ends of the thin plate blank are set in the side U-shaped structure and fixed by the pressing device.

2. The electromagnetic forming apparatus according to claim 1, characterized in that: The array microstructure mold has array microstructure features on its upper and lower sides. A thin plate blank is set on one side of the array microstructure features. A current-carrying plate is provided on the other side of the array microstructure mold. The two ends of the current-carrying plate are in contact with the current collection device. An insulating plate is provided between the current-carrying plate and the array microstructure mold.

3. The electromagnetic forming apparatus according to claim 2, characterized in that: The current-carrying plate is made of pure copper, pure aluminum, copper alloy, or aluminum alloy.

4. The electromagnetic forming apparatus according to claim 1, characterized in that: The array microstructure mold has array microstructure features on both the upper and lower sides, and thin plate blanks are provided on both the upper and lower sides of the array microstructure mold.

5. The electromagnetic forming apparatus according to claim 4, characterized in that: When the thin plate blank is made of titanium alloy or stainless steel with low conductivity and high strength, a driving plate is also provided on the outside of the thin plate blank. The driving plate is made of pure aluminum, pure copper, aluminum alloy or copper alloy. The left and right ends of the driving plate are also inserted into the lower side U-shaped structure of the current collection device and contact the current collection device, and are pressed and fixed by the pressing device.

6. The electromagnetic forming apparatus according to any one of claims 1 to 5, characterized in that: Insulating blocks are provided between the left and right ends of the array microstructure mold and the mold fixing plate.

7. A method for electromagnetic forming of a metal thin-plate array microstructure, characterized in that: The forming process using the electromagnetic forming apparatus described in claim 6 includes the following specific steps: 1) Determine the size and parameters of the array microstructure mold, current carrier plate, and current collection device according to the specifications of the metal sheet microstructure array to be formed; 2) Based on the size and parameters of the array microstructure mold, current carrier plate and current collector obtained in step 1), fabricate the array microstructure mold and current collector; 3) Determine whether a drive board is needed based on the material of the microstructure array of the metal sheet to be formed; 4) Determine the discharge parameters based on the material and microstructure characteristics of the metal sheet microstructure array to be formed; 5) Place the thin plate blank or current-carrying plate to be formed on the upper and lower sides of the array microstructure mold, and fit the side U-shaped structure of the lower part of the current collection device on the left and right ends of the array microstructure mold. The current collection device is in contact with the thin plate blank or current-carrying plate. 6) Use an edge-pressing device to press the sheet material to be formed; 7) Turn on the pulse power supply to energize the forming coil and begin forming; 8) After forming is completed, remove the edge pressing device and take out the formed sheet.

Images