Method and apparatus for pipe flange processing based on concave magnet collector

Abstract

This invention relates to a pipe flanging method based on a U-shaped magnet collector. The method involves determining the parameters of a drive coil and the dimensions of the U-shaped magnet collector, fabricating the U-shaped magnet collector, selecting the wire material and diameter, and winding the drive coil using a winding machine. A pressing die is used to fix the end of the non-flanged area of ​​the pipe to be formed. The length of the flanging forming area of ​​the pipe to be formed is adjusted by adjusting the length of the pipe to be formed within the pressing die. The drive coil and the U-shaped magnet collector are sequentially arranged and fixed inside the flanging forming area of ​​the pipe to be formed. Power is supplied to the drive coil, and the discharge time of the pulse power supply is controlled to flanging the pipe to be formed. The invention also discloses a corresponding pipe flanging processing device. This invention improves the uniformity of pipe flanging and the flatness of the flanging forming area, solving the problem of buckling at the flanged part of the pipe due to end effects in traditional pipe flanging methods.

Description

Technical Field

[0001] This invention belongs to the field of metal forming and manufacturing, and specifically relates to a method and apparatus for flanging pipe fittings based on a concave magnet. Background Technology

[0002] In aerospace, automotive, and other industries, the use of lightweight alloys is more energy-efficient and environmentally friendly. Flanging is a crucial process in lightweight alloy processing, directly impacting the forming accuracy of parts and the quality of subsequent assembly and welding. Lightweight alloys exhibit low formability at room temperature and are prone to springback and tearing, leading to bottlenecks in traditional flanging processes in materials processing. Therefore, electromagnetic forming technology, as an advanced method utilizing pulsed electromagnetic force to drive high-speed deformation of metal workpieces, has been extensively studied.

[0003] Traditional electromagnetic flanging suffers from uneven electromagnetic force distribution during the flanging process due to structural location and high-speed deformation. The electromagnetic force on the workpiece decreases as the flanging angle increases, leading to buckling and an uneven flanging surface. To address this issue, Zhang et al. reported a method in *Forging Technology* entitled "Buckling Problem in Bidirectional Loading Electromagnetic Flanging of Pipe Fittings." This method improves the ratio of radial to axial electromagnetic force using a bidirectional loading coil, thus resolving the buckling problem in bidirectional loading pipe fitting flanging. However, the dual-coil structure used in this method is complex and inefficient. [1] In their paper "A Method for Flanging Small Tubes Using Attractive Electromagnetic Force with Magnetizer," published in *High Power Laser & Particle Number*, Li Shengfei et al. reported a method for electromagnetic flanging of micro-aluminum alloy tubes. Existing methods place the drive coil on the outside of the tube end and use a dual-frequency current method to generate an attractive electromagnetic force to achieve flanging, solving the problem of electromagnetic flanging of small tubes. However, the buckling problem during the flanging process remains unresolved. [2] .

[0004] In summary, current research on electromagnetic flanging still has gaps in the field of improving workpiece buckling problems. Furthermore, methods that improve buckling by changing the drive coil structure suffer from poor flexibility and high costs. When processing workpieces of different sizes, it is necessary to remanufacture the corresponding drive coils. In contrast, the new magnet collector is simpler to manufacture, lower in cost, and more flexible than drive coils. By changing different magnet collectors, electromagnetic flanging of workpieces of different sizes can be performed, shortening the manufacturing cycle and facilitating mass production.

[0005] References:

[0006] [1] Zhang Wuming, Zhang Wang, Qiu Li. Buckling problem in electromagnetic flanging of bidirectional loading pipe fittings [J]. Forging Technology, 2022, 47 (08): 102-110.

[0007] [2] Li Shengfei, Zhu Xianfeng, Liu Ziwei, et al. Method for flanging small tubes with attraction electromagnetic force and magnet collector [J]. High Power Laser and Particle Beams, 2023, 35 (05): 106-116. Summary of the Invention

[0008] The technical problem of this invention is that in the traditional workpiece flanging process, due to structural position, high-speed deformation and other reasons, the workpiece buckles due to uneven distribution of electromagnetic force during the flanging process, resulting in uneven workpiece flanging.

[0009] The purpose of this invention is to address the above-mentioned problems by providing a pipe flange processing method based on a concave magnet. By utilizing the protrusions on the surface of the concave magnet, the distance between the concave magnet and the pipe is reduced, thereby increasing the electromagnetic force on the end of the pipe flange forming area corresponding to the protrusion of the concave magnet, improving the uniformity of pipe flange forming, and solving the problem of buckling at the flanged part of the pipe due to the end effect in traditional pipe flange methods.

[0010] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0011] The method for flanging pipe fittings based on U-shaped magnet collectors includes the following steps:

[0012] Step 1: Based on the forming specifications of the pipe fitting, determine the parameters of the drive coil and the size parameters of the U-shaped magnet collector, and then manufacture the U-shaped magnet collector;

[0013] Step 2: Based on the parameters of the drive coil obtained in Step 1, select the corresponding wire and wire diameter, and wind the drive coil using a winding machine;

[0014] Step 3: After the annealing pretreatment of the pipe to be formed, the end of the non-flanged area of ​​the pipe to be formed is fixed by the pressing die. The length of the flanged forming area of ​​the pipe to be formed is adjusted by adjusting the length of the pipe to be formed in the pressing die.

[0015] Step 4: Arrange the drive coil and the U-shaped magnet collector in sequence inside the flange forming area of ​​the tube to be formed and fix them;

[0016] Step 5: Connect the drive coil to the pulse power supply via a switch, turn on the switch to supply power to the drive coil, and control the discharge time of the pulse power supply to flanging the tube to be formed.

[0017] Step 6: Determine whether the flanging effect of the pipe fitting meets the flanging specifications. If it meets the flanging specifications, the process ends; otherwise, proceed to step 5 to perform flanging processing on the pipe fitting again.

[0018] The concave-shaped magnet collector has a first convex ring and a second convex ring at its end. The cross-section of the concave-shaped magnet collector is concave. The concave-shaped magnet collector has a slit. The first convex ring and the second convex ring of the concave-shaped magnet collector are used to reduce the distance between the concave-shaped magnet collector and the pipe. Under the action of the magnetic field of the driving coil, the induced current on the first convex ring and the second convex ring increases the magnetic flux density of the corresponding part of the pipe and increases the electromagnetic force on the corresponding part, thereby improving the electromagnetic field of the pipe flange area and improving the uniformity of the pipe flange forming.

[0019] Preferably, in step 1, a simulation model of electromagnetic flanging of a pipe fitting, including a driving coil, a U-shaped magnet collector, and a pipe fitting, is constructed using finite element software. A pulse current is applied to the driving coil in the simulation model to simulate the flanging effect of the pipe fitting. The flanging effect is compared with the flanging forming effect of the pipe fitting. The parameters of the driving coil, the size parameters of the U-shaped magnet collector, and the relative positions of the driving coil, the U-shaped magnet collector, and the pipe fitting are repeatedly adjusted to obtain the optimal parameters of the driving coil and the size parameters of the U-shaped magnet collector.

[0020] Taking a pipe fitting with an outer diameter of 50mm as an example, in a preferred embodiment, the height of the first convex ring is 3-3.8mm, and the thickness of the first convex ring is 0.8-1.2mm. The height of the second convex ring is 3.1-3.9mm, and the thickness of the second convex ring is 1.3-1.7mm.

[0021] Preferably, the longitudinal distance between the reinforcing conductor ring and the end of the bulging area of ​​the pipe fitting is 10 mm.

[0022] Preferably, the distance between the drive coil and the concave magnet is 1-2 mm.

[0023] Preferably, the distance between the concave magnet and the tube to be formed is 7-9 mm.

[0024] Preferably, in step 4, a hydraulic device is used to fix the tube to be formed, the U-shaped magnet collector, and the drive coil, and the pressure of the hydraulic device is 0.8-1.6 MPa.

[0025] The above-mentioned pipe flange processing device based on the U-shaped magnet collector includes a U-shaped magnet collector, a drive coil, a pulse power supply, and a pressing die; the drive coil is connected to the pulse power supply via a switch; the pressing die is used to fix the end of the non-flanged area of ​​the pipe to be formed, and the length of the flange forming area of ​​the pipe to be formed is adjusted by adjusting the length of the pipe to be formed in the pressing die.

[0026] Furthermore, the end of the concave magnet is provided with a first convex ring and a second convex ring. The cross-section of the concave magnet is concave, and the concave magnet is provided with a slit. The first convex ring and the second convex ring of the concave magnet are used to reduce the distance between the concave magnet and the pipe. Under the action of the magnetic field of the driving coil, the induced current on the first convex ring and the second convex ring increases the magnetic flux density of the corresponding part of the pipe and increases the electromagnetic force on the corresponding part, thereby improving the electromagnetic field of the pipe flange area and improving the uniformity of the pipe flange forming.

[0027] Compared with the prior art, the beneficial effects of the present invention include:

[0028] 1) This invention arranges a U-shaped magnet collector between the drive coil and the flanged tube, and utilizes the two protrusions of the U-shaped magnet collector facing the flanged tube to reduce the distance between the U-shaped magnet collector and the tube, thereby improving the electromagnetic field of the flanged forming area of ​​the tube and increasing the electromagnetic force on the end of the flanged forming area corresponding to the protrusion. This solves the problem of buckling of the flanged part of the tube due to the end effect in the traditional tube flanged method. This invention improves the uniformity of the flanged forming of the tube and the flatness of the flanged forming area of ​​the tube.

[0029] 2) This invention increases the flexibility of pipe flanging by using a concave magnet. Traditional electromagnetic flanging requires the model of the workpiece to correspond closely with the size parameters of the drive coil. Therefore, the traditional electromagnetic flanging process requires changing the drive coil when flanging different models of workpieces, resulting in low utilization of the drive coil. This invention can achieve pipe flanging of various forming specifications without changing the drive coil by using concave magnets with different size parameters, thereby reducing the difficulty of pipe flanging and improving productivity.

[0030] 3) The concave magnet collector of the present invention is easy to manufacture and economical, while the manufacturing process of traditional electromagnetic flanged drive coils is cumbersome and expensive. Compared with drive coils, the concave magnet collector of the present invention has lower manufacturing costs and is easier to manufacture. In addition, the concave magnet collector of the present invention is located between the workpiece and the drive coil, which improves the eddy current distribution of the drive coil and withstands the electromagnetic force on the drive coil caused by the induced eddy currents of the workpiece, thus extending the service life of the drive coil. Attached Figure Description

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

[0032] Figure 1 This is a flowchart illustrating the pipe flange processing method based on a concave magnet collector according to an embodiment of the present invention.

[0033] Figure 2 This is a schematic diagram of the pipe flange processing device according to an embodiment of the present invention.

[0034] Figure 3 This is a circuit diagram showing the connection between the drive coil and the pulse power supply in an embodiment of the present invention.

[0035] Figure 4 This is a schematic diagram of a concave magnet collecting device according to an embodiment of the present invention.

[0036] Figure 5 This is a simulation result of the traditional electromagnetic flanging method for pipe fittings.

[0037] Figure 6 This is a simulation effect diagram of the pipe flange processing method based on the concave magnet collector of the present invention.

[0038] Explanation of reference numerals in the attached drawings: 1. Drive coil; 2. U-shaped magnet collector; 2.1. First convex ring; 2.2. Second convex ring; 3. Tube to be flanged; 3. Flanging forming area; 4. Pressing die. Detailed Implementation

[0039] In this embodiment, by introducing a U-shaped magnet between the drive coil and the forming tube, the electromagnetic force at the end of the tube flanging forming area is strengthened, the electromagnetic force in the middle of the tube flanging forming area is reduced, the buckling phenomenon during the tube flanging process is improved, and the tube is flanged to the ideal angle.

[0040] like Figure 1 As shown, the method for flanging pipe fittings based on U-shaped magnet collectors includes the following steps:

[0041] Step 1: Based on the forming specifications of the pipe fitting, determine the parameters of the drive coil and the size parameters of the U-shaped magnet collector, and then manufacture the U-shaped magnet collector;

[0042] A simulation model of electromagnetic flanging for pipe fittings was established using the finite element software COMSOL Multiphysics, including a U-shaped magnet collector, the pipe fitting to be formed, and a drive coil. A pulsed current was applied to the drive coil to generate electromagnetic force within the pipe fitting. The final forming effect was analyzed, model parameters were adjusted, and the uniformity of the final forming effect and the flatness of the flanging forming area were compared to obtain the optimal geometric dimensions of the U-shaped magnet collector, the parameters of the drive coil, and the spacing parameters between the U-shaped magnet collector, the drive coil, and the pipe fitting.

[0043] Step 2: Based on the parameters of the drive coil obtained in Step 1, select the corresponding wire and wire diameter, and wind the drive coil using a winding machine;

[0044] Step 3: After the annealing pretreatment of the pipe to be formed, the end of the non-flanged area of ​​the pipe to be formed is fixed by the pressing die. The length of the flanged forming area of ​​the pipe to be formed is adjusted by adjusting the length of the pipe to be formed in the pressing die.

[0045] Step 4: Arrange the drive coil and the U-shaped magnet collector in sequence inside the flange forming area of ​​the tube to be formed and fix them;

[0046] Step 5: Connect the drive coil to the pulse power supply via an air switch, control the air switch to turn on, supply power to the drive coil, and control the discharge time of the pulse power supply to flip the edge of the tube to be formed.

[0047] Step 6: Determine whether the flanging effect of the pipe fitting meets the flanging specifications. If it meets the flanging specifications, the process ends; otherwise, proceed to step 5 to perform flanging processing on the pipe fitting again.

[0048] like Figure 2 As shown, the pipe flange processing device of the embodiment includes a drive coil 1, a U-shaped magnet collector 2, a pipe to be flanged 3, a pressing die 4, and a pulse power supply.

[0049] The drive coil 1 is used to provide an electromagnetic field and induce eddy currents in the tube to be flanged.

[0050] like Figure 4 As shown, the concave magnet 2 is used to improve the magnetic field distribution. The first convex ring 2.1 and the second convex ring 2.2 of the concave magnet 2 are used to strengthen the magnetic field strength at the end of the pipe fitting flanging forming area. The pipe fitting to be flanged is selected according to the actual situation. The pressing die is used to control the range of the pipe fitting flanging forming area 3.1, and the material can be selected according to the actual situation.

[0051] like Figure 3 As shown, the drive coil 1 is connected to the pulse power supply via an air switch. In this embodiment, the pulse power supply is a capacitor power supply with a capacitance of 320μF and a voltage of 6.02kV.

[0052] In this embodiment, the capacitor power supply is first charged by an external charging system, and then the switch is turned off after the capacitor power supply is fully charged. The electrical energy stored in the capacitor power supply is applied to the drive coil through a discharge circuit. The discharge circuit consists of a diode, a freewheeling resistor, a line inductance, and a line resistance.

[0053] During the pipe flangeing process, the electromagnetic force F acting on the pipe fitting satisfies the following formula:

[0054]

[0055] In the formula, The induced eddy current density in the pipe fitting, Let F be the magnetic flux density around the pipe. The direction of the electromagnetic force F follows Lenz's law.

[0056] In this embodiment, the metal fitting is made of AA5083-O aluminum alloy, the number of turns of the drive coil is 3×5, and the cross-sectional area of ​​each coil turn is 2mm×4mm. Figure 2The inner diameter of the tube is 117.5 mm, and the inner diameter of the drive coil is 103.5 mm. After introducing the U-shaped magnet collector, the inner diameter of the tube and the inner diameter of the drive coil remain unchanged. The inner diameter of the U-shaped magnet collector is 110.5 mm, and the outer diameter is 115.3 mm. The outer diameter of the first convex ring is 116.3 mm, and the outer diameter of the second convex ring is 116.6 mm. The axes of the tube to be flanged, the drive coil, and the U-shaped magnet collector are all on the same straight line.

[0057] The capacitor power supply is charged by an external charging system. After the capacitor power supply is charged, the air switch is closed to load the electrical energy stored in the capacitor power supply onto the drive coil. In a short time, the drive coil generates a strong pulse magnetic field and induces eddy currents in the tube. The protruding part of the concave magnet can reduce the distance between the magnet and a specific area of ​​the tube to be flanged, and increase the magnetic flux density at the end of the flanged forming area of ​​the tube during the flanged process. By adjusting the magnetic flux density distribution of the flanged part of the workpiece, the electromagnetic force on the flanged part of the workpiece is improved, and the buckling phenomenon is effectively solved.

[0058] This embodiment uses COMSOL Multiphysics software for simulation. The simulation results of the traditional electromagnetic flange method for pipe fittings are as follows: Figure 5 As shown, the simulation results of the pipe fitting flanging processing method based on the U-shaped magnet collector are as follows: Figure 6 As shown in the diagram, the size and direction of the arrows represent the magnitude and direction of the electromagnetic force F. (Compare) Figure 5 and Figure 6 The buckling phenomenon during the pipe flangeing process using the method of the present invention is significantly improved, and the electromagnetic force is more evenly distributed during the pipe flangeing process.

Claims

1. A method for flanging pipe fittings based on a concave magnet collector, characterized in that, The end of the concave magnet has a first convex ring and a second convex ring. The thickness of the second convex ring is greater than that of the first convex ring. The cross-section of the concave magnet is concave. The concave magnet has a slit. The first and second convex rings of the concave magnet reduce the distance between the concave magnet and the tube. Under the action of the magnetic field of the driving coil, the induced current on the first and second convex rings increases the magnetic flux density of the corresponding part of the tube and increases the electromagnetic force on the corresponding part, so as to achieve uniform flanging of the tube. The pipe fitting flanging process includes the following steps: Step 1: Based on the forming specifications of the pipe fitting, determine the parameters of the drive coil and the size parameters of the U-shaped magnet collector, and then manufacture the U-shaped magnet collector; Step 2: Based on the parameters of the drive coil obtained in Step 1, select the corresponding wire and wire diameter, and wind the drive coil using a winding machine; Step 3: After the annealing pretreatment of the pipe to be formed, the end of the non-flanged area of ​​the pipe to be formed is fixed by the pressing die. The length of the flanged forming area of ​​the pipe to be formed is adjusted by adjusting the length of the pipe to be formed in the pressing die. Step 4: Arrange the drive coil and the U-shaped magnet collector in sequence inside the flange forming area of ​​the tube to be formed and fix them; Step 5: Connect the drive coil to the pulse power supply via a switch, turn on the switch to supply power to the drive coil, and control the discharge time of the pulse power supply to flanging the tube to be formed. Step 6: Determine whether the flanging effect of the pipe fitting meets the flanging specifications. If it meets the flanging specifications, the process ends; otherwise, proceed to step 5 to perform flanging processing on the pipe fitting again.

2. The pipe fitting flanging processing method based on a concave magnet as described in claim 1, characterized in that, In step 1, a simulation model of electromagnetic flanging of a pipe fitting is constructed using finite element software, which includes a driving coil, a U-shaped magnet collector, and the fitting itself. A pulse current is applied to the driving coil in the simulation model to simulate the flanging effect of the fitting. The flanging effect is compared with the flanging forming effect of the fitting. The parameters of the driving coil, the size parameters of the U-shaped magnet collector, and the relative positions of the driving coil, the U-shaped magnet collector, and the fitting are repeatedly adjusted to obtain the optimal parameters of the driving coil and the size parameters of the U-shaped magnet collector.

3. The pipe fitting flanging processing method based on a concave magnet as described in claim 1, characterized in that, The height of the first convex ring is 3-3.8mm, and the thickness of the first convex ring is 0.8-1.2mm.

4. The pipe fitting flanging processing method based on a concave magnet as described in claim 1, characterized in that, The height of the second convex ring is 3.1-3.9mm, and the thickness of the second convex ring is 1.3-1.7mm.

5. The pipe fitting flanging processing method based on a concave magnet as described in claim 1, characterized in that, The distance between the drive coil and the concave magnet is 1-2mm.

6. The pipe fitting flanging processing method based on a concave magnet as described in claim 1, characterized in that, The distance between the concave magnet and the tube to be formed is 7-9mm.

7. The pipe fitting flanging processing method based on a concave magnet as described in claim 1, characterized in that, In step 4, a hydraulic device is used to fix the tube to be formed, the U-shaped magnet collector, and the drive coil. The pressure of the hydraulic device is 0.8-1.6 MPa.

8. The pipe fitting flanging processing method based on a concave magnet as described in claim 1, characterized in that, In step 5, the pulse power supply is a capacitor power supply with a capacitance of 320 kJ / m³. The voltage of the capacitor power supply is 6.02kV.

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