Pipe fitting flanging machining method and device based on U-shaped magnetic collector

Abstract

The invention relates to a pipe fitting flanging processing method based on a U-shaped magnetic collector, which comprises the following steps of: determining parameters of a driving coil and size parameters of the U-shaped magnetic collector, and manufacturing the U-shaped magnetic collector; selecting the wire rod and the wire diameter of the coil, and winding the coil into a driving coil through a winding machine; the end of the non-flanging area of the to-be-formed pipe fitting is fixed through a blank pressing die, and the length of the flanging forming area of the to-be-formed pipe fitting is adjusted by adjusting the length of the to-be-formed pipe fitting in the blank pressing die; a driving coil and a U-shaped magnetic collector are sequentially arranged on the inner side of the flanging forming area of the pipe fitting to be formed and fixed; and supplying power to the driving coil, controlling the discharge time of the pulse power supply, and flanging the to-be-formed pipe fitting. The invention further discloses a corresponding pipe fitting flanging machining device. By means of the pipe fitting flanging forming method, the pipe fitting flanging forming uniformity and the flatness of a pipe fitting flanging forming area are improved, and the problem that a pipe fitting flanging part is bent due to the end effect in a traditional pipe fitting flanging method is solved.

Description

Technical Field

[0001] The invention belongs to the field of metal forming and manufacturing, and in particular relates to a pipe flanging processing method and device based on a concave-shaped magnetic collector. Background Art

[0002] In the fields of aerospace, automotive industry, etc., the use of lightweight light alloys is more energy-saving and environmentally friendly. The flanging process is very important in the processing of light alloys, which directly affects the forming accuracy of parts and the subsequent assembly and welding quality. Light alloys have low forming plasticity at room temperature, and have disadvantages such as easy rebound and tearing, which leads to bottlenecks in the field of material processing for traditional flanging processing. Therefore, electromagnetic forming technology has been widely studied as an advanced method that uses pulsed electromagnetic force to drive high-rate deformation of metal workpieces.

[0003] Due to the structural position and high-speed deformation of traditional electromagnetic flanging, the electromagnetic force on the part of the workpiece to be flanging will decrease as the flanging angle increases, which will eventually cause the workpiece to buckle due to uneven distribution of electromagnetic force during the flanging process, and the workpiece flanging will be uneven. In response to the above problems, Zhang Wuming et al. published a paper titled "Buckling Problems in Electromagnetic Flanging of Bidirectionally Loaded Tubes" in "Forging Technology" and reported a method of improving the buckling problem of tubes by improving the ratio of radial electromagnetic force to axial electromagnetic force through bidirectionally loaded coils. This method solves the buckling problem of bidirectionally loaded tube flanging, but the double coil structure it uses has the disadvantages of complex equipment and low economic efficiency. [1] In the article “Method for flanging small tubes with attracting electromagnetic force using a magnetic collector” published in High Power Laser and Particle Number, Li Shengfei et al. reported a process for electromagnetic flanging of tiny aluminum alloy tubes. The existing method places the driving coil on the outside of the tube end and uses the dual-frequency current method to generate attracting electromagnetic force to achieve flanging, which solves the problem of electromagnetic flanging of small tubes, but still does not solve the problem of buckling of the workpiece during flanging. [2] .

[0004] In summary, the current research on electromagnetic flanging still has gaps in the field of improving the buckling problem of workpieces. In addition, the method of improving the buckling phenomenon by changing the structure of the driving coil has the disadvantages of poor flexibility and high cost. When processing workpieces of different models, the corresponding driving coils need to be remade. Compared with the driving coil, the new magnetic collector is simple to make, low in cost, and high in flexibility. By replacing different magnetic collectors, electromagnetic flanging can be performed on workpieces of different sizes, shortening the manufacturing cycle and being more conducive to mass production.

[0005] References: [1] Zhang Wuming, Zhang Wang, Qiu Li. Buckling problem in electromagnetic flanging of bidirectionally loaded pipe fittings[J]. Forging Technology, 2022, 47(08): 102-110.

[0006] [2] Li Shengfei, Zhu Xianfeng, Liu Ziwei, et al. Attractive electromagnetic force flanging method for small tubes with magnetic collector [J]. High Power Laser and Particle Beams, 2023, 35 (05): 106-116. Summary of the invention

[0007] The technical problem of the present invention is that in the traditional workpiece flanging process, due to reasons such as structural position and high-speed deformation, the workpiece is buckled during the flanging process due to uneven distribution of electromagnetic force, resulting in uneven flanging of the workpiece.

[0008] The purpose of the present invention is to address the above-mentioned problems and to provide a pipe flanging processing method based on a concave-shaped magnetic collector. The protrusions on the surface of the concave-shaped magnetic collector are utilized to reduce the distance between the concave-shaped magnetic collector and the pipe, so that the electromagnetic force on the end of the pipe flanging forming area corresponding to the protrusions of the concave-shaped magnetic collector is increased, thereby improving the uniformity of the pipe flanging forming and solving the problem of buckling of the pipe flanging part due to the end effect in the traditional pipe flanging method.

[0009] In order to achieve the above object, the technical solution provided by the present invention is: The pipe flanging processing method based on the concave-shaped magnetic collector comprises the following steps: Step 1: According to the forming specifications of the pipe fitting, the parameters of the driving coil and the size parameters of the concave-shaped magnetic collector are determined, and the concave-shaped magnetic collector is manufactured; Step 2: According to the parameters of the driving coil obtained in step 1, select the corresponding wire material and wire diameter, and use a winding machine to wind the driving coil; Step 3: After the tube to be formed is annealed and pre-treated, the end of the non-flanged area of ​​the tube to be formed is fixed by a pressing die, and the length of the flanging forming area of ​​the tube to be formed is adjusted by adjusting the length of the tube to be formed in the pressing die; Step 4: Arrange the driving coil and the concave-shaped magnetic collector in sequence on the inner side of the flanging forming area of ​​the pipe to be formed and fix them; Step 5: Connect the drive coil to the pulse power supply via the switch, control the switch to be turned on, supply power to the drive coil, and control the discharge time of the pulse power supply to flanging the pipe to be formed; Step 6: Determine whether the flanging effect of the pipe fitting meets the flanging specifications of the pipe fitting. If it meets the flanging specifications, the process ends; otherwise, execute step 5 to perform flanging on the pipe fitting again.

[0010] A first convex ring and a second convex ring are provided at the end of the concave-shaped magnetic collector, the cross-section of the concave-shaped magnetic collector is concave, and a break is provided on the concave-shaped magnetic collector. The first convex ring and the second convex ring of the concave-shaped magnetic collector are used to reduce the distance between the concave-shaped magnetic collector and the pipe fitting. 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 fitting and increases the electromagnetic force on the corresponding part, thereby improving the electromagnetic field in the flanging area of ​​the pipe fitting and improving the uniformity of the flanging forming of the pipe fitting.

[0011] Preferably, in step 1, a finite element software is used to construct a pipe electromagnetic flanging simulation model including a driving coil, a concave-shaped magnetizer and a pipe, and a pulse current is applied to the driving coil in the pipe electromagnetic flanging simulation model to simulate the flanging effect of the pipe. By comparing the flanging forming effect of the pipe, the parameters of the driving coil and the dimensional parameters of the concave-shaped magnetizer and the relative positions of the driving coil, the concave-shaped magnetizer and the pipe are repeatedly adjusted to obtain the optimal parameters of the driving coil and the dimensional parameters of the concave-shaped magnetizer.

[0012] Taking the pipe to be formed with an outer diameter of 50 mm as an example, in a preferred solution, the height of the first convex ring is 3-3.8 mm, the thickness of the first convex ring is 0.8-1.2 mm, the height of the second convex ring is 3.1-3.9 mm, and the thickness of the second convex ring is 1.3-1.7 mm.

[0013] Preferably, the longitudinal distance between the reinforcing conductor ring and the end of the tube expansion zone is 10 mm.

[0014] Preferably, the distance between the driving coil and the concave-shaped magnetic collector is 1-2 mm.

[0015] Preferably, the distance between the concave-shaped magnetic collector and the pipe to be formed is 7-9 mm.

[0016] Preferably, in step 4, hydraulic equipment is used to fix the pipe to be formed, the concave-shaped magnetic collector and the driving coil, and the pressure of the hydraulic equipment is 0.8-1.6 MPa.

[0017] The above-mentioned pipe flanging processing device based on the concave-shaped magnetic collector includes a concave-shaped magnetic collector, a driving coil, a pulse power supply and a pressing die; the driving coil is connected to the pulse power supply via a switch; the pressing die is used to fix the end of the non-flanging area of ​​the pipe to be formed, and adjust the length of the flanging forming area of ​​the pipe to be formed by adjusting the length of the pipe to be formed in the pressing die.

[0018] Furthermore, a first convex ring and a second convex ring are provided at the end of the concave-shaped magnetic collector, the cross-section of the concave-shaped magnetic collector is concave, and a break is provided on the concave-shaped magnetic collector. The first convex ring and the second convex ring of the concave-shaped magnetic collector are used to reduce the distance between the concave-shaped magnetic collector and the pipe fitting. 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 fitting and increases the electromagnetic force on the corresponding part, thereby improving the electromagnetic field in the flanging area of ​​the pipe fitting and improving the uniformity of the flanging forming of the pipe fitting.

[0019] Compared with the prior art, the beneficial effects of the present invention include: 1) The present invention arranges a concave-shaped magnetic collector between the driving coil and the flanging pipe, utilizes the two protrusions of the concave-shaped magnetic collector facing the flanging pipe, reduces the distance between the concave-shaped magnetic collector and the pipe, improves the electromagnetic field in the flanging forming zone of the pipe, increases the electromagnetic force on the end of the flanging forming zone of the pipe corresponding to the protrusion, solves the problem of buckling of the flanging part of the pipe due to the end effect in the traditional flanging method of the pipe, and improves the uniformity of the flanging forming of the pipe and the flatness of the flanging forming zone of the pipe.

[0020] 2) The present invention increases the flexibility of pipe flanging processing by using a concave-shaped magnetic collector. The traditional electromagnetic flanging process requires that the model of the formed workpiece and the size parameters of the driving coil are highly consistent. Therefore, the traditional electromagnetic flanging process needs to replace the driving coil when flanging workpieces of different models, and the utilization rate of the driving coil is low. The present invention can realize pipe flanging processing of various forming specifications by using concave-shaped magnetic collectors with different size parameters without replacing the driving coil, thereby reducing the difficulty of pipe flanging processing and improving productivity.

[0021] 3) The concave-shaped magnetic collector of the present invention is easy to manufacture and economical, while the manufacturing process of the traditional electromagnetic flanging drive coil is cumbersome and expensive. Compared with the drive coil, the concave-shaped magnetic collector of the present invention has low manufacturing cost and low manufacturing difficulty. In addition, the concave-shaped magnetic collector of the present invention is located between the workpiece and the drive coil, which improves the eddy current distribution of the drive coil, withstands the electromagnetic force of the workpiece reacting to the drive coil due to the induced eddy current, and can extend the service life of the drive coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] Figure 1 The present invention is a flowchart of a method for flanging a pipe based on a concave-shaped magnetic concentrator according to an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of a pipe flanging processing device according to an embodiment of the present invention.

[0025] Figure 3The figure is a circuit diagram of the connection between the driving coil and the pulse power supply according to an embodiment of the present invention.

[0026] Figure 4 Schematic diagram of a concave-shaped magnetic collector device according to an embodiment of the present invention.

[0027] Figure 5 This is the simulation effect diagram of the traditional pipe electromagnetic flanging method.

[0028] Figure 6 It is a simulation effect diagram of the pipe flanging processing method based on the concave-shaped magnetic collector of the present invention.

[0029] Explanation of reference numerals: driving coil 1, concave magnetic collector 2, first convex ring 2.1, second convex ring 2.2, pipe to be flanging 3, flanging forming area 3.1, and crimping die 4. DETAILED DESCRIPTION

[0030] In the embodiment, a concave-shaped magnetic collector is introduced between the driving coil and the forming tube to strengthen the electromagnetic force at the end of the tube flanging forming zone, reduce the electromagnetic force in the middle of the tube flanging forming zone, improve the buckling phenomenon during the tube flanging process, and make the tube flanging to an ideal angle.

[0031] like Figure 1 As shown, the pipe flanging processing method based on the concave-shaped magnetic collector includes the following steps: Step 1: According to the forming specifications of the pipe fitting, the parameters of the driving coil and the size parameters of the concave-shaped magnetic collector are determined, and the concave-shaped magnetic collector is manufactured; The finite element software COMSOL Multiphysics was used to establish a simulation model of electromagnetic flanging of pipe fittings, including a concave magnetic collector, 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 and the flatness of the flanging forming area of ​​the pipe fitting were compared to obtain the optimal geometric size parameters of the concave magnetic collector and the parameters of the driving coil, as well as the spacing parameters between the concave magnetic collector, the driving coil, and the pipe fitting.

[0032] Step 2: According to the parameters of the driving coil obtained in step 1, select the corresponding wire material and wire diameter, and use a winding machine to wind the driving coil; Step 3: After the tube to be formed is annealed and pre-treated, the end of the non-flanged area of ​​the tube to be formed is fixed by a pressing die, and the length of the flanging forming area of ​​the tube to be formed is adjusted by adjusting the length of the tube to be formed in the pressing die; Step 4: Arrange the driving coil and the concave-shaped magnetic collector in sequence on the inner side of the flanging forming area of ​​the pipe to be formed and fix them; Step 5: Connect the driving coil to the pulse power supply via the air switch, control the air switch to be turned on, supply power to the driving coil, and control the discharge time of the pulse power supply to flanging the pipe to be formed; Step 6: Determine whether the flanging effect of the pipe fitting meets the flanging specifications of the pipe fitting. If it meets the flanging specifications, the process ends; otherwise, execute step 5 to perform flanging on the pipe fitting again.

[0033] like Figure 2 As shown, the pipe flanging processing device of the embodiment includes a driving coil 1, a concave-shaped magnetic collector 2, a pipe to be flanging 3, a pressing die 4 and a pulse power supply.

[0034] The driving coil 1 is used to provide an electromagnetic field and induce eddy currents in the pipe to be flanging.

[0035] like Figure 4 As shown, the concave-shaped magnetic collector 2 is used to improve the magnetic field distribution, and the first convex ring 2.1 and the second convex ring 2.2 of the concave-shaped magnetic collector 2 are used to strengthen the magnetic field strength at the end of the flanging forming area of ​​the pipe fitting; the pipe fitting to be flanging is selected according to actual conditions; the pressing die is used to control the range of the flanging forming area 3.1 of the pipe fitting, and the material can be selected according to actual conditions.

[0036] like Figure 3 As shown, the driving coil 1 is connected to the pulse power supply via an air switch. In the embodiment, the pulse power supply adopts a capacitor power supply, the capacitance of the capacitor power supply is 320 μF, and the voltage of the capacitor power supply is 6.02 kV.

[0037] In the embodiment, the capacitor power supply is first charged by an external charging system, and the switch is turned off after the capacitor power supply is fully charged. The electric energy stored in the capacitor power supply is loaded onto the driving coil through a discharge circuit. The discharge circuit is composed of a diode, a freewheeling circuit resistor, a line inductor and a line resistor.

[0038] During the flanging process of the pipe fitting, the electromagnetic force F applied to the pipe fitting satisfies the following formula:

[0039] In the formula, is the induced eddy current density in the pipe, is the magnetic flux density around the pipe. The direction of the electromagnetic force F satisfies Lenz's law.

[0040] In the embodiment, the metal pipe is made of AA5083-O aluminum alloy material, the number of turns of the driving coil is 3×5, and the cross-sectional area of ​​each turn of the coil is 2 mm×4 mm. Figure 2The inner diameter of the middle pipe is 117.5mm, and the inner diameter of the driving coil is 103.5mm. After the concave magnetic collector is introduced, the inner diameter of the pipe remains unchanged, the inner diameter of the driving coil remains unchanged, the inner diameter of the concave magnetic collector is 110.5mm, and the outer diameter is 115.3mm, of which the outer diameter of the first convex ring is 116.3mm, and the outer diameter of the second convex ring is 116.6mm. The axis of the pipe to be flanging, the driving coil and the concave magnetic collector are located on the same straight line.

[0041] The capacitor power supply is charged by an external charging system. After the capacitor power supply is charged, the air switch is controlled to close, and the electric energy stored in the capacitor power supply is loaded onto the driving coil. In a short time, the driving coil will generate a strong pulse magnetic field and induce eddy currents in the pipe. The raised part of the concave-shaped magnetic collector can reduce the distance between the magnetic collector and the specific area of ​​the pipe to be flanging, increase the magnetic flux density at the end of the flanging forming area of ​​the pipe during the flanging process, and improve the electromagnetic force on the flanging part of the workpiece by adjusting the magnetic flux density distribution of the flangable part of the workpiece, thereby effectively solving the buckling phenomenon.

[0042] This embodiment is simulated by COMSOL Multiphysics multi-physics software. The simulation results of the traditional pipe electromagnetic flanging method are as follows: Figure 5 As shown in the figure, the simulation results of the pipe flanging processing method based on the concave magnetic collector are as follows Figure 6 As shown in the figure, the size and direction of the arrows represent the size and direction of the electromagnetic force F. Figure 5 and Figure 6 The buckling phenomenon in the pipe flanging process using the method of the present invention is significantly improved, and the electromagnetic force is more evenly distributed in the pipe flanging process.

Claims

1. A pipe flanging processing method based on a concave-shaped magnetic collector, characterized in that: The end of the concave-shaped magnetic collector is provided with a first convex ring and a second convex ring, the cross section of the concave-shaped magnetic collector is concave-shaped, and a fracture is provided on the concave-shaped magnetic collector. The first convex ring and the second convex ring of the concave-shaped magnetic collector reduce the distance between the concave-shaped magnetic collector and the pipe fitting. 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 fitting and increases the electromagnetic force on the corresponding part, so as to realize uniform flanging of the pipe fitting. The pipe flanging processing method comprises the following steps: Step 1: According to the forming specifications of the pipe fitting, the parameters of the driving coil and the size parameters of the concave-shaped magnetic collector are determined, and the concave-shaped magnetic collector is manufactured; Step 2: According to the parameters of the driving coil obtained in step 1, select the corresponding wire material and wire diameter, and use a winding machine to wind the driving coil; Step 3: After the tube to be formed is annealed and pre-treated, the end of the non-flanged area of ​​the tube to be formed is fixed by a pressing die, and the length of the flanging forming area of ​​the tube to be formed is adjusted by adjusting the length of the tube to be formed in the pressing die; Step 4: Arrange the driving coil and the concave-shaped magnetic collector in sequence on the inner side of the flanging forming area of ​​the pipe to be formed and fix them; Step 5: Connect the drive coil to the pulse power supply via the switch, control the switch to be turned on, supply power to the drive coil, and control the discharge time of the pulse power supply to flanging the pipe to be formed; Step 6: Determine whether the flanging effect of the pipe fitting meets the flanging specifications of the pipe fitting. If it meets the flanging specifications, the process ends; otherwise, execute step 5 to perform flanging on the pipe fitting again.

2. The pipe flanging processing method based on the concave-shaped magnetic collector according to claim 1 is characterized in that: In the step 1, a simulation model of an electromagnetic flanging of a pipe comprising a driving coil, a concave-shaped magnetizer and a pipe is constructed using finite element software, a pulse current is applied to the driving coil in the simulation model of the electromagnetic flanging of the pipe, and the flanging effect of the pipe is simulated and compared with the flanging forming effect of the pipe, the parameters of the driving coil and the size parameters of the concave-shaped magnetizer as well as the relative positions of the driving coil, the concave-shaped magnetizer and the pipe are repeatedly adjusted to obtain the optimal parameters of the driving coil and the size parameters of the concave-shaped magnetizer.

3. The pipe flanging processing method based on the concave-shaped magnetic collector according to claim 1 is characterized in that: The height of the first convex ring is 3-3.8 mm, and the thickness of the first convex ring is 0.8-1.2 mm.

4. The pipe flanging processing method based on the concave-shaped magnetic collector according to claim 1 is characterized in that: The height of the second convex ring is 3.1-3.9 mm, and the thickness of the second convex ring is 1.3-1.7 mm.

5. The pipe flanging processing method based on the concave-shaped magnetic collector according to claim 1 is characterized in that: The distance between the driving coil and the concave magnetic collector is 1-2 mm.

6. The pipe flanging processing method based on the concave-shaped magnetic collector according to claim 1 is characterized in that: The distance between the concave magnetic collector and the pipe to be formed is 7-9 mm.

7. The pipe flanging processing method based on the concave-shaped magnetic collector according to claim 1 is characterized in that: In step 4, a hydraulic device is used to fix the pipe to be formed, the concave-shaped magnetic collector and the driving coil, and the pressure of the hydraulic device is 0.8-1.6 MPa.

8. The pipe flanging processing method based on the concave-shaped magnetic collector according to claim 1 is characterized in that: In step 5, the pulse power supply is a capacitor power supply, and the capacitance of the capacitor power supply is 320 , the voltage of the capacitor power supply is 6.02kV.

9. The device for the pipe flanging processing method based on the concave-shaped magnetic collector according to any one of claims 1 to 8, characterized in that: The device includes a concave-shaped magnetic collector, a driving coil, a pulse power supply and a pressing die; the driving coil is connected to the pulse power supply via a switch; the pressing die is used to fix the end of the non-flanging area of ​​the pipe to be formed, and adjust the length of the flanging forming area of ​​the pipe to be formed by adjusting the length of the pipe to be formed in the pressing die.

10. A concave-shaped magnetic collector, characterized in that: Cooperating with the driving coil, it is used for flanging processing of pipe fittings. The end of the concave-shaped magnetic collector is provided with a first convex ring and a second convex ring. The cross-section of the concave-shaped magnetic collector is concave. The concave-shaped magnetic collector is provided with a break. The first convex ring and the second convex ring of the concave-shaped magnetic collector are used to reduce the distance between the concave-shaped magnetic collector and the pipe fitting. 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 fitting and increases the electromagnetic force on the corresponding part, thereby improving the electromagnetic field in the flanging area of ​​the pipe fitting and improving the uniformity of the flanging forming of the pipe fitting.

Images