Manufacturing Method of Electric Field / Electromagnetic Field Coupling for Metal Bellows

Abstract

A manufacturing method for the coupling of electric field / electromagnetic field of a metal bellows. Place an induction coil inside the blank to be formed and place them together between the upper die and the lower die of the forming device, and insulate between the induction coil and the blank to be formed. Apply a low-voltage high-pulse current to both ends of the blank to be formed and heat the blank to the set temperature under the action of the Joule heat effect. Then apply an instantaneous current to both ends of the induction coil to make the induction coil generate an electromagnetic force acting on the blank, thereby completing the forming of the metal bellows. The present invention realizes one-time die setting and integral forming, simplifies the tooling and molds of traditional forming, reduces the processes of bellows forming. In addition, the blank is formed at a high strain rate, significantly improving the plastic deformation ability of titanium alloy and high-strength aluminum alloy; the thermal effect and non-thermal effect of the pulse current further improve the forming performance of titanium alloy and high-strength aluminum alloy. At the same time, the high-speed non-contact forming using electromagnetic force solves the problem of serious heat loss caused by the contact between the blank heated by the pulse current and the mold.

Description

Technical Field

[0001] The present invention relates to a technology in the field of pipe forming, specifically a method for manufacturing metal bellows by electric field / electromagnetic field coupling. Background Art

[0002] The electromagnetic forming technology of metal bellows utilizes the electromagnetic force it receives in the electromagnetic field to achieve the rapid forming of bellows. Golovashchenko et al. found that compared with traditional aluminum alloy forming methods, the forming limit of electromagnetic forming of aluminum alloy increases by 2.5 times. The existing electromagnetic pulse forming method can only process one or a few wave bands at a time. For bellows with more wave bands, only the segmented forming method can be used for manufacturing, which increases the forming difficulty of the bellows and reduces the forming accuracy of the bellows. In addition, titanium alloy and high-strength aluminum alloy have poor forming performance at room temperature, poor local drawability, and large springback after unloading, seriously affecting the forming accuracy of the bellows. Titanium alloy bellows usually adopt high-temperature gas inflation forming, but the forming rate is slow and the sealing requirement of the forming device is high; in industry, the hot forming-cold die quenching (HFQ) process is often used to form high-strength aluminum alloy. However, in the traditional HFQ process, after the aluminum alloy sheet is heated and solution-treated, it needs to be quickly transferred into the mold for forming, which is difficult to achieve precise temperature control and reduces the forming efficiency of the material at the same time. Summary of the Invention

[0003] Aiming at the deficiencies that the prior art cannot significantly improve the deformation performance of titanium alloy and high-strength aluminum alloy and is prone to cause the rupture of titanium alloy and high-strength aluminum alloy during high-speed forming, the present invention proposes a method for manufacturing metal bellows by electric field / electromagnetic field coupling, realizing integral forming with one-time mold loading, simplifying the tooling and molds of traditional forming, reducing the forming process of the bellows. In addition, the tube blank is formed at a high strain rate, significantly improving the metal plastic deformation ability; the thermal effect and non-thermal effect of the pulsed current further enhance the forming performance of titanium alloy and high-strength aluminum alloy, and at the same time, the high-speed non-contact forming of the electromagnetic force is used to solve the problem of serious heat loss caused by the contact between the pulsed current-heated blank and the mold.

[0004] The present invention is realized by the following technical solutions:

[0005] The present invention relates to a method for manufacturing metal bellows by electric field / electromagnetic field coupling. An induction coil is placed inside the tube blank to be formed and is placed between the upper die and the lower die of the forming device together. An insulation is provided between the induction coil and the tube blank to be formed. A low-voltage large-pulse current is applied to both ends of the tube blank to be formed, and the tube blank is heated up under the action of the Joule heat effect. Then, an instantaneous pulse current is applied to both ends of the induction coil, so that the induction coil generates an electromagnetic force acting on the tube blank, and the forming of the metal bellows is quickly completed.

[0006] The low-voltage large-pulse current is specifically: directly applied by a 12V / 20000A low-voltage large-current power supply device.

[0007] The instantaneous pulse current mentioned above is specifically as follows: An instantaneous current is passed through the electromagnetic coil to generate an electromagnetic force acting on the tube blank, and the discharge power supply is cut off after the forming of the metal bellows is completed.

[0008] The axis of the induction coil coincides with the axis of the tube blank.

[0009] During the forming process, the temperature of the tube blank is measured in real time by an infrared thermal imager. When the heating temperature of the tube blank reaches the set temperature and remains stable, the press drives the upper die to move downward to close the die with the lower die, and a certain die closing force is applied.

[0010] The present invention relates to a metal bellows electric field / electromagnetic field coupling forming device for realizing the above method, including: upper and lower die modules arranged oppositely, a metal tube blank arranged therebetween, and a core coil located inside the tube blank, wherein: the core coil is connected to a discharge device, the upper and lower die modules close the die to form the tube blank after closing the die, and the temperature measuring device is arranged facing the tube blank and measures the temperature of the tube blank before closing the die.

[0011] Technical effects

[0012] In the forming of the bellows of the present invention, heating is carried out by a low-voltage large pulse current, and an electromagnetic force acting on the metal tube blank is generated by using the instantaneous pulse current through the electromagnetic coil. The high-speed non-contact electromagnetic force can avoid the bottleneck problem that the temperature of the tube blank drops significantly due to heat conduction caused by die loading, so as to improve its forming performance by coupling the electric field and the electromagnetic field. By applying a pulsed large current to heat simultaneously to reduce the flow stress and improve the plasticity, and applying an electromagnetic force to improve the forming performance. The electromagnetic force formed by the intense discharge of the discharge circuit in a short time is used to solve the problem that the loading time is too long in the previous electric-assisted forming, and the heat of the blank is quickly conducted to the die, resulting in serious heat loss; the pulsed large current heating is used to solve the problems of difficult forming of titanium alloy and high-strength aluminum alloy and limited effect of electromagnetic force in improving the formability. This technical means creatively couples and utilizes electric-assisted forming and electromagnetic forming to realize the high-efficiency and high-plasticity forming of metal bellows. Description of the drawings

[0013] Figure 1 Schematic diagram of the metal bellows to be formed by the present invention;

[0014] Figure 2 Schematic structural diagram of the forming device of the present invention;

[0015] Figure 3 Flow chart of the forming method of the embodiment of the present invention;

[0016] In the figure: lower die base 1, guide pillar / guide bushing 2, lower die 3, upper die base 4, upper die 5, metal tube blank 6, electromagnetic coil 7, electromagnetic coil iron core 8, tube blank fixing device 9, iron core fixing device 10, insulating cushion block 11, wire 12, low-voltage high-current pulse power supply 13, high-voltage instantaneous discharge power supply 14. Specific implementation mode

[0017] In this embodiment, a processed die and a metal tube blank are used as blanks for experiments. As Figure 2 shown, this embodiment relates to a device for forming a metal bellows by coupling an electric field and an electromagnetic field, including: upper and lower die modules arranged oppositely, a metal tube blank 6 arranged therebetween, and a core coil located inside the metal tube blank 6. Among them: the core coil is connected to a power supply device, and after the upper and lower die modules are closed, the metal tube blank 6 is formed, and a temperature measuring device is arranged directly opposite the metal tube blank 6 and measures the temperature of the tube blank before closing the die.

[0018] The upper die module includes: an upper die base 4 and an upper die 5 fixedly connected thereto.

[0019] The lower die module includes: a lower die base 1, a lower die 3 fixedly connected thereto, a tube blank fixing device 9 and an insulating cushion block 11 arranged between the lower die base 1 and the lower die 3.

[0020] The core coil includes: an electromagnetic coil 7 and an electromagnetic coil iron core 8 located inside it, and the electromagnetic coil iron core 8 is fixed through an iron core fixing device 10.

[0021] The temperature measuring device includes: an infrared thermal imager and a computer. Among them: the infrared thermal imager transmits the measured temperature data to the computer, and the computer processes the data and records it for inspection and analysis.

[0022] The power supply device includes: a low-voltage high-current pulse power supply 13 and a high-voltage instantaneous discharge power supply 14. Among them: the low-voltage high-current pulse power supply 13 is connected to both ends of the metal tube blank 6 (using conductive clamps), and the high-voltage instantaneous discharge power supply 14 is connected to both ends of the core coil.

[0023] As Figure 3 shown, this is a method for manufacturing a metal bellows by coupling an electric field and an electromagnetic field based on the above-mentioned forming device, which is realized through the following steps:

[0024] S1. Prepare materials: The diameter of the metal tube blank is 50 - 100 mm, and the thickness of the tube blank is 1 - 2 mm;

[0025] S2. Assemble: Install the forming device on a press, fix the metal tube blank 6 on the tube blank fixing device 9, connect the metal tube blank 6 to the low-voltage high-current pulse power supply 13 through a wire, and connect the electromagnetic coil 7 to the high-voltage pulse power supply 14 through a wire;

[0026] S3. Heating: Turn on the low-voltage high-current pulse power supply 13 and keep it closed until the bellows forming is completed. The tube blank is heated by the Joule heat effect through the closed loop composed of the pulse power supply, the electrode, and the tube blank. The temperature of the tube blank is measured by an infrared thermal imager. When the tube blank is heated to the set temperature and remains stable, the press drives the upper die 5 to move downward to close the mold with the lower die 3, and a certain mold closing force is applied.

[0027] S4. Forming: Turn on the high-voltage instantaneous discharge power supply 14. The electromagnetic coil is energized with an instantaneous current to generate a pulsed magnetic field, generating an electromagnetic force acting on the tube blank. After the metal bellows is formed, the switches of the pulse power supplies 13 and 14 are cut off. The press moves upward to open the mold, and the formed metal bellows is taken out.

[0028] This embodiment integrates the temperature measurement function, and can adjust the magnitude of the power supply voltage and the pulse frequency according to the measured temperature and the change of the tube blank forming effect, ensuring that the temperature and the forming force are appropriate during the composite field assisted forming process, and the forming effect is stable.

[0029] Compared with the prior art, this device significantly reduces the forming difficulty of titanium alloy and high-strength aluminum alloy. From the experimental situation of electric assistance, usually, electric heating can reduce the forming force of cold forming by one order of magnitude. In addition, the loading time of electric-assisted forming is 5 - 10 minutes, but electromagnetic forming compresses this time to within 1 s. The whole process can be approximated as an adiabatic process, avoiding a large decrease in the temperature of the blank during the forming process, significantly improving the deformation performance of titanium alloy and high-strength aluminum alloy, and improving the forming quality.

[0030] 1) The pulse power supply directly heats the metal tube blank, without the need to heat the entire set of upper and lower molds. The heating rate is fast, reducing energy consumption. At the same time, it reduces the oxidation degree of titanium alloy and high-strength aluminum alloy, and improves the forming performance of titanium alloy and high-strength aluminum alloy.

[0031] 2) Utilizing the high-speed forming characteristics of the electromagnetic field to avoid a large amount of heat loss after the blank contacts the mold during the electric-assisted forming process, ensuring that the temperature is relatively constant during the tube blank forming process, and improving the forming quality of the metal bellows.

[0032] 3) The electric field / electromagnetic field coupling manufacturing method realizes the rapid and efficient forming of metal bellows, simplifies the forming process, improves its production efficiency, and can achieve the overall forming of the bellows in one forming.

[0033] The above specific implementation can be locally adjusted by those skilled in the art in different ways without departing from the principles and purposes of the present invention. The protection scope of the present invention is subject to the claims and is not limited by the above specific implementation. All implementation solutions within its scope are subject to the constraints of the present invention.

Claims

1. A manufacturing method for the coupling of electric field / electromagnetic field of a metal bellows, characterized in that Place the induction coil inside the tube blank to be formed and place them together between the upper die and the lower die of the forming device. Insulate between the induction coil and the tube blank to be formed. Continuously apply a low-voltage large-pulse current to both ends of the tube blank to be formed. While heating the tube blank to the set temperature under the action of the Joule heat effect, apply an instantaneous pulse current to both ends of the induction coil to make the induction coil generate an electromagnetic force acting on the tube blank, thus completing the forming of the metal bellows; The above-mentioned low-voltage large-pulse current always passes through the tube blank to be formed before the forming is completed. Specifically, it is directly and continuously applied by a 12V / 20000A low-voltage large-power supply device during the forming process; The above-mentioned instantaneous pulse current is specifically as follows: Turn on the high-voltage discharge power supply to generate an instantaneous current, pass it into the electromagnetic coil to generate an electromagnetic force acting on the tube blank, and cut off the discharge power supply after the forming of the metal bellows is completed; During the forming process, use an infrared thermal imager to measure the temperature of the tube blank in real time. When the heating temperature of the tube blank reaches the set temperature and remains stable, the press drives the upper die to move downward to close the die with the lower die and apply a certain closing force.

2. The method for manufacturing a metal bellows by electric field / electromagnetic field coupling according to claim 1, characterized in that, The axis of the above-mentioned induction coil coincides with the axis of the tube blank.

3. A metal bellows electromagnetic coupling forming device for implementing the manufacturing method of the metal bellows electric field / electromagnetic field coupling described in claim 1 or 2, characterized in that It includes: Upper and lower die modules arranged oppositely, a metal tube blank arranged therebetween, and a core coil located inside the metal tube blank. Among them: The core coil is connected to the discharge device. After the upper and lower die modules are closed, the metal tube blank is formed. The temperature measuring device is arranged facing the metal tube blank and measures the temperature of the metal tube blank before closing the die.

4. The electromagnetic coupling forming device for metal bellows according to claim 3, characterized in that, The above-mentioned upper die module includes: an upper die base and an upper die fixedly connected thereto.

5. The electromagnetic coupling forming device for metal bellows according to claim 3, characterized in that, The above-mentioned lower die module includes: a lower die base, a lower die fixedly connected thereto, a tube blank fixing device and an insulating spacer arranged between the lower die base and the lower die.

6. The electromagnetic coupling forming device for the metal bellows according to claim 3, characterized in that, The above-mentioned core coil includes: an electromagnetic coil and an electromagnetic coil iron core located inside it. The electromagnetic coil iron core is fixed through a core fixing device.

7. The electromagnetic coupling forming device for a metal bellows according to claim 3, characterized in that, The above-mentioned temperature measuring device includes: an infrared thermal imager and a computer. Among them: The infrared thermal imager transmits the measured temperature data to the computer, and the computer processes the data and records it for inspection and analysis.

8. The electromagnetic coupling forming device for metal bellows according to claim 3, characterized in that, The above-mentioned discharge device includes: a low-voltage large-current pulse power supply and a high-voltage instantaneous discharge power supply. Among them: The low-voltage large-current pulse power supply is connected to both ends of the metal tube blank, and the high-voltage discharge power supply is connected to both ends of the core coil.

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