Pipe fitting electromagnetic bulging method and bulging device adopting reinforced conductor ring

Abstract

The invention relates to a pipe fitting electromagnetic bulging method adopting a reinforced conductor ring, and belongs to the field of metal workpiece electromagnetic forming control. The strengthening conductor ring is additionally arranged between the driving coil and the to-be-formed pipe fitting, the strengthening conductor ring is arranged at the end of the bulging area of the to-be-formed pipe fitting, the strengthening conductor ring is used for strengthening the magnetic field intensity of the end of the bulging area of the to-be-formed pipe fitting, and uniform bulging of the pipe fitting is achieved through the strengthening conductor ring. The invention further discloses a corresponding pipe fitting electromagnetic bulging device. According to the method, the problem that the bulging uniformity of the pipe fitting is affected due to the end effect in a traditional pipe fitting bulging method is solved, uniform bulging of the pipe fitting is achieved, the flatness of the bulging pipe fitting is improved, and the problem that the wall thickness of a bulging area of the pipe fitting is reduced in the traditional pipe fitting bulging method is effectively solved.

Description

Technical Field

[0001] The invention belongs to the field of electromagnetic forming control of metal workpieces, and in particular relates to a tube electromagnetic bulging method and a bulging device using a reinforced conductor ring. Background Art

[0002] At present, the new energy vehicle industry has been vigorously developed, and lightweight technology is an effective way to reduce the total weight of the vehicle. Studies have shown that every 10% reduction in the curb weight of a traditional vehicle can reduce fuel consumption by 8%. At the same time, if the vehicle is reduced by 100kg, CO2 emissions can be reduced by 5 g / km, and 20 kg of exhaust gas can be reduced throughout the entire service life. At present, the most mature lightweight material is aluminum alloy, which has been used in the new energy vehicle industry.

[0003] Electromagnetic forming technology is a high-speed processing method that uses pulsed electromagnetic force. Electromagnetic forming technology can improve forming efficiency and expand the forming range of materials. At the same time, it can also reduce production costs and improve forming quality. Therefore, electromagnetic forming technology is an effective choice for processing lightweight materials.

[0004] The existing literature on electromagnetic forming to improve the uniformity of pipe fittings mainly focuses on changing the shape of the coil and using a magnetic collector to change the magnetic field distribution. In 2018, Qiu Li's paper "Analysis of the expansion electromagnetic force and deformation characteristics of concave coil electromagnetic tube based on finite element method" [1] "It is proposed to use concave coils to replace the original cylindrical coils to improve the forming performance. The basic principle is to use concave coils to strengthen the electromagnetic force at both ends of the forming. This method solves the problems of uneven magnetic field forming and thinning of wall thickness, but due to the complex coil winding, the processing cost is high and it is not easy to package. The patent invention with publication number CN114769408A "Electromagnetic bulging method and device for bidirectional loading of inner and outer walls of magnetic collector [2] "An electromagnetic bulging device is disclosed, in which the main devices are forming coils and a new type of magnetic collector. The invention uses a bidirectional loading method for the inner and outer walls of the annular magnetic collector to improve the axial uniformity of the bulging and effectively suppress the thinning of the wall thickness during the bulging process. However, this new type of magnetic collector has a complex structure and a high manufacturing process. After manufacturing, the application range is mostly workpieces of the same size, the reuse rate is low, and the control method is not flexible.

[0005] In summary, the prior art lacks a method and device for improving electromagnetic forming performance with flexible control methods and lower costs.

[0006] References: [1]Li Q, Yijie Y, Qi [2] Qiu Li, He Qin, Wu Weiye. Electromagnetic bulging method and device for bidirectional loading of inner and outer walls of magnetic collector[P]. Hubei Province: CN202210422853.9, 2024-03-12. Summary of the invention The purpose of the present invention is to address the above-mentioned problems and to provide a method for electromagnetic bulging of pipe fittings using a reinforced conductor ring. By introducing a reinforced conductor ring between the driving coil and the formed workpiece, the reinforced conductor ring strengthens the magnetic field strength at the end of the bulging zone of the pipe fitting to be formed, thereby achieving uniform bulging of the pipe fitting.

[0007] In order to achieve the above object, the technical solution provided by the present invention is: The electromagnetic bulging method of a pipe fitting using a reinforced conductor ring comprises the following steps: Step 1: Determine the drive coil parameters and make the drive coil according to the material and forming specifications of the pipe to be formed; Step 2: Determine the size parameters of the reinforcing conductor ring according to the drive coil parameters and the tube forming specifications; Step 3: According to the parameters obtained in step 2, a reinforcing conductor ring and a conductor ring bracket are manufactured, and the reinforcing conductor ring is arranged on the conductor ring bracket; Step 4: Arrange the pipe to be formed, the conductor ring bracket, and the driving coil on the workpiece base in sequence and fix them; Step 5: Connect the drive coil to the pulse power supply via the switch, control the air switch to power the drive coil, control the discharge time of the pulse power supply, and perform electromagnetic bulging on the pipe to be formed; Step 6: Determine whether the bulging effect of the pipe fitting meets the forming specifications of the pipe fitting. If it meets the forming specifications, the process ends; otherwise, execute step 5 to perform electromagnetic bulging on the pipe fitting again.

[0008] Preferably, the reinforcing conductor ring is provided with a break.

[0009] Preferably, the cross section of the reinforcing conductor ring is rectangular.

[0010] Preferably, in step 2, a finite element software COMSOL Multiphysics is used to construct a tube electromagnetic bulging simulation model including a driving coil, a reinforcing conductor ring and a tube, a pulse current is applied to the driving coil in the tube electromagnetic bulging simulation model, the bulging effect of the tube is simulated, and compared with the tube forming specifications, the size parameters of the reinforcing conductor ring are adjusted so that the tube bulging effect meets the requirements of the tube forming specifications, and the size parameters of the reinforcing conductor ring are determined by simulation.

[0011] Preferably, the longitudinal distance between the reinforcing conductor ring and the end of the expansion zone of the tube is 10 mm.

[0012] Preferably, the distance between the reinforcing conductor ring and the driving coil is 2 mm-8 mm.

[0013] Preferably, the distance between the reinforcing conductor ring and the tube to be formed is 1 mm-5 mm.

[0014] Preferably, the reinforcing conductor ring is made of copper.

[0015] Preferably, in step 5, the pulse power supply is a capacitor power supply, the capacitance of the capacitor power supply is 10-1000 μF, and the discharge voltage of the capacitor power supply is 1-10 kV.

[0016] The bulging device of the above-mentioned electromagnetic bulging method for pipe fittings comprises a driving coil, a reinforcing conductor ring, a conductor ring bracket and a pulse power supply; the conductor ring bracket is used to support and fix the reinforcing conductor ring; the driving coil is connected to the pulse power supply via a switch.

[0017] Furthermore, the bulging device also includes a workpiece base, which is used to fix the pipe, the conductor ring bracket and the driving coil.

[0018] Compared with the prior art, the beneficial effects of the present invention include: 1) The tube bulging method of the present invention increases the magnetic field strength at the end of the bulging zone of the tube to be formed by adding a reinforcing conductor ring between the driving coil and the bulging tube, thereby solving the problem of the traditional tube bulging method affecting the uniformity of the tube bulging due to the end effect. The present invention realizes uniform bulging of the tube and effectively improves the problem of thinning of the wall thickness of the tube bulging zone in the traditional tube bulging method.

[0019] 2) The cross-section of the reinforcing conductor ring of the present invention is rectangular, which is easy to manufacture and has low cost. Compared with the method of improving the driving coil, it is less difficult; and by replacing the reinforcing conductor rings with different size parameters, different tube bulging effects can be achieved to meet the requirements of various tube forming specifications.

[0020] 3) The tube bulging method of the present invention can also solve the problem of the traditional tube bulging method affecting the uniformity of tube bulging due to the end effect by adding a shielded conductor ring between the driving coil and the bulging tube to weaken the magnetic field strength in the middle of the tube bulging area, thereby achieving uniform bulging of the tube.

[0021] 4) The cross-section of the shielded conductor ring of the present invention is rectangular, which is easy to manufacture and has low cost, and is less difficult than improving the driving coil. Different tube expansion effects can be achieved by replacing shielded conductor rings with different size parameters or using multiple shielded conductor rings to meet the requirements of various tube forming specifications.

[0022] 5) The present invention combines a shielded conductor ring with a reinforced conductor ring for tube bulging. The shielded conductor ring weakens the magnetic field strength and electromagnetic force in the middle of the tube bulging zone, and the reinforced conductor ring is used to enhance the magnetic field strength at the end of the bulging zone of the tube to be formed. Compared with using the reinforced conductor ring or the shielded conductor ring alone, the flatness of the bulging zone after the tube bulging can be further improved, and the problem of thinning of the wall thickness of the tube bulging zone in the traditional tube bulging method can be improved.

[0023] 6) The present invention can reduce the reaction force of the induced current of the pipe on the driving coil during the pipe forming process by using a reinforced conductor ring and / or a shielded conductor ring, thereby effectively protecting the driving coil and extending the service life of the driving coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] Figure 1 The figure is a schematic flow chart of the electromagnetic bulging method for a pipe using a reinforced conductor ring according to the first embodiment.

[0026] Figure 2 FIG. 4 is an equivalent circuit diagram of the connection between the driving coil and the power supply according to an embodiment of the present invention.

[0027] Figure 3 Schematic diagram of the tube bulging device of Example 1.

[0028] Figure 4 FIG. 1 is a schematic diagram of a reinforced conductor ring according to the first embodiment.

[0029] Figure 5 Schematic diagram of the induced eddy current of the enhanced conductor ring of the first embodiment.

[0030] Figure 6 It is a schematic diagram of a tube expansion device combining a shielded conductor ring and a reinforced conductor ring according to the second embodiment.

[0031] Figure 7 It is a schematic diagram of the shielding conductor ring and the strengthening conductor ring of the second embodiment.

[0032] Figure 8 Schematic diagram of the induced eddy currents of the shielding conductor ring and the strengthening conductor ring of the second embodiment.

[0033] Fig. 9 This is a comparison diagram of the forming effects of the electromagnetic bulging method for pipe fittings of Example 1 and the traditional pipe bulging method.

[0034] Description of reference numerals: workpiece base 1 , tube to be formed 2 , expansion zone 201 , conductor ring support 3 , reinforcing conductor ring 4 , driving coil 5 , shielding conductor ring 6 . DETAILED DESCRIPTION

[0035] Embodiment 1 In the embodiment, a reinforcing conductor ring is introduced between the driving coil and the formed workpiece to strengthen the local area where the electromagnetic force is too weak, and finally uniform bulging is achieved. The reinforcing conductor ring has a break and the cross section of the reinforcing conductor ring is rectangular.

[0036] like Figure 1 As shown, the electromagnetic bulging method of a pipe using a reinforced conductor ring comprises the following steps: Step 1: Determine the drive coil parameters and make the drive coil according to the material and forming specifications of the pipe to be formed; Step 2: Determine the size parameters of the reinforcing conductor ring according to the drive coil parameters and the tube forming specifications; The finite element software COMSOL Multiphysics was used to establish a simulation model for electromagnetic bulging of pipe fittings, including a reinforcing conductor ring, a pipe to be formed, and a driving coil. A pulse current was applied to the driving coil to generate electromagnetic force in the pipe fitting. The final forming effect was analyzed, the model parameters were adjusted, and the uniformity of the final forming effect of the pipe fitting was compared to obtain the optimal geometric size and spacing of the reinforcing conductor ring.

[0037] Step 3: According to the parameters obtained in step 2, a reinforcing conductor ring and a conductor ring bracket are manufactured, and the reinforcing conductor ring is arranged on the conductor ring bracket; Step 4: Arrange the pipe to be formed, the conductor ring bracket, and the driving coil on the workpiece base in sequence and fix them; Step 5: Connect the drive coil to the pulse power supply via the switch, control the air switch to power the drive coil, control the discharge time of the pulse power supply, and perform electromagnetic bulging on the pipe to be formed; Step 6: Determine whether the bulging effect of the pipe fitting meets the forming specifications of the pipe fitting. If it meets the forming specifications, the process ends; otherwise, execute step 5 to perform electromagnetic bulging on the pipe fitting again.

[0038] like Figure 3As shown, the electromagnetic bulging device of the first embodiment includes a workpiece base 1, a pipe to be formed 2, a conductor ring bracket 3, a reinforcing conductor ring 4, a driving coil 5 and a pulse power supply. The workpiece base acts on the fixed pipe, the conductor ring bracket and the driving coil, and fixes the pipe to be formed, the conductor ring bracket and the driving coil from the outside to the inside in sequence. The reinforcing conductor ring is nested in the conductor ring bracket. The driving coil 5 is connected to the pulse power supply via an air switch, as shown in FIG. Figure 2 shown.

[0039] In the embodiment, the length of the tube to be formed is 60 mm, the number of the reinforcing conductor rings is 2, the height h of the two reinforcing conductor rings is 8 mm, the width is 2 mm, and the spacing d is 40 mm. The geometric shape of the reinforcing conductor ring is as follows: Figure 4 shown.

[0040] During the electromagnetic bulging process of the pipe, the pulse power supply supplies power to the driving coil, and the induced current of the driving coil, the pipe to be formed and the reinforcing conductor ring is as follows: Figure 5 As shown, an inward current is formed in the driving coil on the right side of the symmetry axis. The reinforcing conductor ring is a metal ring with a break. According to the law of electromagnetic induction, an induced eddy current opposite to the pulse magnetic field is generated on the side of the reinforcing conductor ring close to the driving coil. After two reversals, an induced eddy current identical to the pulse magnetic field is generated at the end of the tube bulging zone, thereby strengthening the electromagnetic field at the end of the tube bulging zone 201 near the reinforcing conductor ring. The introduction of the reinforcing conductor ring causes the electromagnetic force on both ends of the tube to be greater than the electromagnetic force on both ends of the tube in the traditional electromagnetic bulging method. Therefore, the radial electromagnetic force at both ends of the tube is greater, which improves the axial uniformity of the tube, improves the forming effect, and improves the flatness of the bulging zone after the tube is bulged.

[0041] In the embodiment, the tube forming effect of the tube electromagnetic bulging method using the reinforced conductor ring is compared with the traditional tube bulging method. Fig. 9 It can be seen that the electromagnetic bulging method of the pipe using the reinforced conductor ring of the present invention solves the problem that the end effect of the traditional pipe bulging method affects the bulging uniformity of the pipe, and the bulging area of ​​the bulged pipe obtained by the present invention is smoother and more uniform.

[0042] Embodiment 2 The difference from the first embodiment is that the second embodiment adds a shielding conductor ring on the basis of the strengthening conductor ring. The shielding conductor ring is used to weaken the electromagnetic field in the middle of the expansion zone of the tube. Combined with the strengthening conductor ring, the uniformity of the tube is achieved and the flatness of the expansion zone of the tube is improved.

[0043] The electromagnetic bulging method for a pipe combining a shielded conductor ring and a reinforced conductor ring comprises the following steps: Step 1: Determine the drive coil parameters and manufacture the drive coil according to the material and forming specifications of the pipe to be formed.

[0044] Step 2: Determine the size parameters of the reinforcing conductor ring according to the drive coil parameters and the tube forming specifications; The finite element software COMSOL Multiphysics was used to establish a simulation model of electromagnetic bulging of pipe fittings, including a reinforcing conductor ring, a pipe to be formed, and a driving coil. A pulse current was applied to the driving coil to generate electromagnetic force in the pipe fitting, and the pipe forming effect was simulated. The geometric size parameters and spacing of the reinforcing conductor ring were adjusted to make the pipe bulging effect meet the requirements of the pipe forming specifications, and the geometric size parameters and spacing of the reinforcing conductor ring were determined.

[0045] Step 3: Determine the size parameters of the shielding conductor ring according to the size parameters of the reinforcing conductor ring and the pipe forming specifications; Add a shielded conductor ring to the electromagnetic bulging simulation model of the pipe obtained in step 2, use the electromagnetic bulging simulation model of the pipe again to simulate the pipe bulging, adjust the size parameters of the shielded conductor ring, make the bulging area of ​​the bulged pipe after forming the best flatness and uniformity, and obtain the optimal size parameters and number of the shielded conductor ring.

[0046] Step 4: According to the parameters obtained in Step 2 and Step 3, a reinforcing conductor ring, a shielding conductor ring and a conductor ring bracket are manufactured, and the reinforcing conductor ring and the shielding conductor ring are arranged on the conductor ring bracket.

[0047] Step 5: Arrange the pipe to be formed, the conductor ring bracket, and the drive coil on the workpiece base in sequence and fix them.

[0048] Step 6: Connect the drive coil to the pulse power supply via the switch, control the air switch to power the drive coil, control the discharge time of the pulse power supply, and perform electromagnetic bulging on the pipe to be formed.

[0049] Step 7: Determine whether the bulging effect of the pipe fitting meets the forming specifications of the pipe fitting. If it meets the forming specifications, the process ends; otherwise, execute step 6 to perform electromagnetic bulging on the pipe fitting again. Embodiment 2, a tube electromagnetic bulging device combining a shielded conductor ring and a reinforced conductor ring Figure 6 As shown, it includes a workpiece base 1, a pipe to be formed 2, a conductor ring bracket 3, a reinforcing conductor ring 4, a shielded conductor ring 6, a driving coil 5 and a pulse power supply. The workpiece base is used as a fixing device, and the pipe to be formed, the conductor ring bracket, and the driving coil are fixed from the outside to the inside. The shielded conductor ring and the reinforcing conductor ring are equidistantly nested in the conductor ring bracket. The driving coil is connected to the pulse power supply.

[0050] The tube to be formed in the second embodiment is 60 mm, the number of shielded conductor rings is 3, the number of reinforced conductor rings is 2, the height of each shielded conductor ring and reinforced conductor ring is 4 mm, the width is 2 mm, and the spacing between adjacent shielded conductor rings and / or reinforced conductor rings is 6 mm.

[0051] During the electromagnetic bulging process of the pipe, the pulse power supply supplies power to the driving coil, and an inward current is formed in the driving coil on the right side of the symmetry axis. According to the right-hand screw rule, a clockwise magnetic field is generated nearby. The specific geometry of the shielding conductor ring and the strengthening conductor ring of this embodiment is as follows Figure 7 As shown in the figure, the shielded conductor ring is an integral metal ring, so according to the law of electromagnetic induction, it generates an induced eddy current opposite to the driving coil, which weakens the electromagnetic field generated by the driving coil in the middle of the tube expansion zone. The reinforcing conductor ring is a metal cylindrical ring with a thin gap. The reinforcing conductor ring generates an induced eddy current opposite to the pulse magnetic field on the side close to the driving coil. After two reverses near the tube side, it generates an induced eddy current identical to the pulse magnetic field, which strengthens the magnetic field near the reinforcing conductor ring.

[0052] The current directions of the tube to be formed, the driving coil, the shielding conductor ring and the reinforcing conductor ring of this embodiment are as follows: Figure 8 As shown in the figure, the introduction of the shielded conductor ring causes the force on the middle of the pipe to be smaller than the electromagnetic force of the traditional electromagnetic bulging of the pipe, and the introduction of the reinforced conductor ring causes the force on the two ends of the pipe to be larger than the electromagnetic force of the traditional electromagnetic bulging. Therefore, the radial electromagnetic force of the traditional electromagnetic bulging of the pipe, which is small at the two ends and large in the middle, is improved, and the radial electromagnetic force at the two ends and the interval between the shielded conductor ring is larger, so that the axial uniformity is improved and the forming effect is better.

Claims

1. A method for electromagnetic bulging of pipes using a reinforced conductor ring, characterized in that: A reinforcing conductor ring is added between the driving coil and the pipe to be formed. The reinforcing conductor ring is arranged at the end of the bulging zone of the pipe to be formed. The reinforcing conductor ring is used to enhance the magnetic field strength at the end of the bulging zone of the pipe to be formed, and the reinforcing conductor ring is used to achieve uniform bulging of the pipe; The electromagnetic bulging method for pipe fittings comprises the following steps: Step 1: Determine the drive coil parameters and make the drive coil according to the material and forming specifications of the pipe to be formed; Step 2: Determine the size parameters of the reinforcing conductor ring according to the drive coil parameters and the tube forming specifications; Step 3: According to the parameters obtained in step 2, a reinforcing conductor ring and a conductor ring bracket are manufactured, and the reinforcing conductor ring is arranged on the conductor ring bracket; Step 4: Arrange the pipe to be formed, the conductor ring bracket, and the driving coil on the workpiece base in sequence and fix them; Step 5: Connect the driving coil to the pulse power supply via the switch, control the air switch to power the driving coil, control the discharge time of the pulse power supply, and perform electromagnetic bulging on the pipe to be formed; Step 6: Determine whether the expansion effect of the pipe meets the forming specifications of the pipe. If it meets the forming specifications, the process ends. Otherwise, execute step 5 to perform electromagnetic expansion on the pipe again to shield the conductor ring.

2. The electromagnetic bulging method for pipe fittings according to claim 1, characterized in that: The reinforcing conductor ring is provided with a broken shielding conductor ring.

3. The electromagnetic bulging method for pipe fittings according to claim 1, characterized in that: In the step 2, a simulation model of electromagnetic bulging of a pipe including a driving coil, a reinforcing conductor ring and a pipe is constructed using finite element software, a pulse current is applied to the driving coil in the simulation model of electromagnetic bulging of a pipe, the bulging effect of the pipe is simulated, and compared with the forming specifications of the pipe, the size parameters of the reinforcing conductor ring are adjusted so that the bulging effect of the pipe meets the requirements of the forming specifications of the pipe, and the size parameters of the reinforcing conductor ring are determined by simulation to shield the conductor ring.

4. The electromagnetic bulging method for pipe fittings according to claim 1, characterized in that: The cross section of the reinforcing conductor ring is a rectangular shielding conductor ring.

5. The electromagnetic bulging method for pipe fittings according to claim 1, characterized in that: The distance between the reinforcing conductor ring and the driving coil is 2mm-8mm shielding conductor ring.

6. The electromagnetic bulging method for pipe fittings according to claim 1, characterized in that: The distance between the reinforcing conductor ring and the pipe to be formed is 1mm-5mm shielding conductor ring.

7. The electromagnetic bulging method for pipe fittings according to claim 1, characterized in that: The reinforcing conductor ring is made of copper material to form a shielding conductor ring.

8. The electromagnetic bulging method for pipe fittings according to claim 1, characterized in that: In step 5, the pulse power supply is a capacitor power supply, the capacitance of the capacitor power supply is 10-1000 μF, and the discharge voltage of the capacitor power supply is 1-10 kV shielded conductor ring.

9. The bulging device of the tube electromagnetic bulging method based on the reinforced conductor ring according to any one of claims 1 to 8, characterized in that: The bulging device comprises a driving coil, a reinforcing conductor ring, a conductor ring bracket and a pulse power supply; the conductor ring bracket is used to support and fix the reinforcing conductor ring; the driving coil is connected to the pulse power supply via a switch to shield the conductor ring.

10. The bulging device according to claim 9, characterized in that: The bulging device also includes a workpiece base, which is used to fix the pipe, the conductor ring bracket and the driving coil.

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