A method for electromagnetic shaping of high-strength alloys

Abstract

This invention discloses an electromagnetic shaping method for high-strength alloys, relating to the field of metal forming and manufacturing technology. The shaping method includes the following steps: fixing a base below a hydraulic press; fixing the high-strength alloy tube to be shaped on the outside of a positioning column structure; installing a shaping coil on the base and surrounding the high-strength alloy tube, connecting the shaping coil to a pulse power supply; controlling the hydraulic press to press down on the positioning column structure, which drives the high-strength alloy tube to expand and enter the plastic deformation stage; controlling the pulse power supply to discharge to the shaping coil, which generates a pulse current and forms a transient high-strength magnetic field, inducing eddy currents on the surface of the high-strength alloy tube. The eddy currents interact with the external magnetic field added by the shaping coil, generating a high-amplitude electromagnetic force that is initially concentrated on the outer surface of the high-strength alloy tube and diffuses towards the interior of the tube's wall thickness, completing the electromagnetic shaping. After disassembly, the high-strength alloy tube is closer to the target roundness dimension.

Description

Technical Field

[0001] This invention relates to the field of metal forming and manufacturing technology, and specifically to an electromagnetic forming method for high-strength alloys. Background Technology

[0002] High-strength alloys (such as titanium alloys and steel) are widely used in high-end manufacturing fields such as aerospace, automotive, and shipbuilding due to their excellent strength, corrosion resistance, and low density. High-precision forming of high-strength alloy components is crucial for improving equipment performance. Currently, the high-precision forming of high-strength alloy components involves first fixing the metal tube to be shaped within a forming mold, then using a hydraulic press's pressure rod to directly press down on the forming mold, causing it to expand. This forces the mold against the inner wall of the metal tube, expanding it to a preset diameter. Finally, the pressure rod is removed, and the forming mold is disassembled.

[0003] However, traditional high-strength alloy forming technology still has shortcomings. For example, after the metal pipe is mechanically bulged by the bulging mold, most of the residual stress of the metal pipe cannot be eliminated. As a result, after the bulging mold is disassembled, the metal pipe still needs to release a large amount of residual stress, which leads to a significant shrinkage in the diameter of the metal pipe and a large error in the target roundness dimension. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a high-strength alloy electromagnetic straightening method to solve the technical problem that after metal pipes are mechanically bulged by a bulging mold, most of the residual stress of the metal pipes cannot be eliminated, resulting in the metal pipes still needing to release a large amount of residual stress after the bulging mold is disassembled, leading to a large shrinkage in the diameter of the metal pipes and a large error in the target roundness dimension.

[0005] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0006] This invention provides a high-strength alloy electromagnetic straightening method, implemented through a high-strength alloy electromagnetic straightening assembly. The assembly includes a positioning mechanism and an electromagnetic straightening mechanism. The positioning mechanism comprises a connected base and a positioning column structure, the outer peripheral sidewall of which abuts against and fixes the high-strength alloy tube to be straightened. The electromagnetic straightening mechanism includes a pulse power supply and a straightening coil. The pulse power supply is connected to the positive and negative terminals of the straightening coil, which is connected to the base. The straightening coil is sleeved on the positioning column structure and spaced apart from its outer peripheral sidewall. The high-strength alloy electromagnetic straightening method includes the following steps:

[0007] Secure the base to the bottom of the hydraulic press and position it with screws;

[0008] The high-strength alloy pipe fitting to be shaped is sleeved on the outside of the positioning post structure and fixed by the positioning post structure;

[0009] The calibration coil is mounted and fixed on the base and set around the high-strength alloy tube. The electrodes of the calibration coil are connected to the pulse power supply.

[0010] The hydraulic press's pressure rod presses down on the positioning column structure, which then expands to press against the inner wall of the high-strength alloy pipe, causing the high-strength alloy pipe to expand to a preset diameter, thus achieving the plastic deformation stage.

[0011] The control pulse power supply discharges to the shaping coil, which generates a pulse current and forms a transient high-strength magnetic field (peak magnetic flux density up to 12T), inducing eddy currents on the surface of the high-strength alloy pipe. The eddy currents interact with the external magnetic field added by the shaping coil to generate a high-amplitude electromagnetic force. The electromagnetic force is initially concentrated on the outer surface of the high-strength alloy pipe, and then diffuses into the interior of the pipe wall thickness, effectively avoiding stress concentration and inducing the pipe to release internal residual stress within milliseconds, thereby completing the electromagnetic shaping.

[0012] Disconnect the alignment coil from the base and remove the alignment coil. Then lift the hydraulic press lever and remove the high-strength alloy pipe after alignment.

[0013] In some embodiments, the positioning mechanism further includes a plurality of support rods arranged around the periphery of the positioning column structure. One end of each support rod is connected to the base, and the other end is connected to the alignment coil. The inner wall of the alignment coil is evenly spaced from the outer peripheral wall of the positioning column structure.

[0014] In some embodiments, the calibration coil includes a first insulating ring, a second insulating ring, a coil frame, and an induction coil. The first insulating ring and the second insulating ring are respectively connected to the two ends of the coil frame. The induction coil is wound around the coil frame, and the positive and negative terminals of the induction coil are connected to the pulse power supply.

[0015] In some embodiments, the positioning mechanism further includes a plurality of bulging support blocks, which are arranged circumferentially to form the positioning column structure. A drive slot is formed between the inner walls of the plurality of bulging support blocks, and one end of each of the plurality of bulging support blocks is slidably connected to the base.

[0016] In some embodiments, the end of the bulging support block connected to the base is provided with a first arc-shaped groove, and the multiple first arc-shaped grooves of the multiple bulging support blocks are connected to each other to form a first annular groove, and a first elastic ring is engaged in the first annular groove.

[0017] In some embodiments, the positioning mechanism further includes a pressing member that is slidably inserted into the drive slot and is capable of pressing against the plurality of bulging support blocks during sliding to drive the plurality of bulging support blocks away from each other during sliding.

[0018] In some embodiments, the pressing member includes a central cone and a connecting plate, one end of the central cone is connected to the connecting plate, the other end of the central cone is slidably inserted into the drive slot, and the connecting plate is detachably connected to the pressure rod of the hydraulic press.

[0019] In some embodiments, the outer peripheral sidewall of the central cone is formed into a frustum shape, and the drive slot is a frustum slot adapted to the outer peripheral sidewall of the central cone.

[0020] In some embodiments, the pressing element includes an epoxy block that connects the central cone and the connecting plate.

[0021] Compared with existing technologies, the high-strength alloy electromagnetic shaping assembly provided by this invention first fixes the high-strength alloy tube to be shaped using a positioning mechanism. The positioning mechanism includes a base and a positioning column structure. The outer peripheral sidewall of the positioning column structure is used to abut and fix the high-strength alloy tube, ensuring its stability during processing. Then, the pressure rod of a hydraulic press is used to press down on the positioning column structure, causing it to expand and press against the inner wall of the high-strength alloy tube, causing the tube to expand to a preset diameter and reach the plastic deformation stage. At this time, a pulse current is supplied to the shaping coil using a pulse power supply. The shaping coil generates an instantaneous strong magnetic field, which induces eddy currents inside the high-strength alloy tube. Simultaneously, the shaping coil generates an additional electromagnetic force acting on the surface of the tube to eliminate most of the residual stress. After the high-strength alloy tube is disassembled, its rebound size is small, closer to the target size, and the error is small. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the electromagnetic shaping method for high-strength alloys provided in an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of the high-strength alloy electromagnetic alignment component provided in an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the electromagnetic alignment mechanism provided in an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the positioning mechanism provided in an embodiment of the present invention;

[0026] Figure 5 This is a disassembly diagram of the positioning mechanism provided in an embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of the structure of the bulging support block provided in an embodiment of the present invention;

[0028] Figure 7 This is a schematic diagram of the structure of the base provided in an embodiment of the present invention;

[0029] Figure 8 This is a schematic diagram of the pulse current waveform input to the calibration coil by the pulse power supply provided in an embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] To address the technical problem in existing technologies where residual stress in metal pipes cannot be promptly eliminated after mechanical bulging with a bulging die, resulting in significant residual stress release even after die removal and substantial diameter shrinkage and deviation from the target dimension, this invention provides a high-strength alloy electromagnetic straightening method. This method enables immediate electromagnetic straightening after mechanical bulging, eliminating residual stress through the interaction of pulsed magnetic fields and eddy currents, significantly reducing pipe diameter shrinkage and improving forming accuracy.

[0032] It should be noted that the high-strength alloy electromagnetic straightening method described in this invention is used for, but not limited to, the straightening of steel pipe fittings. For ease of explanation, this invention will only use the application of the high-strength alloy electromagnetic straightening method to the straightening of steel pipe fittings as an example. The principle of the high-strength alloy electromagnetic straightening method applied to other types of equipment is essentially the same as that applied to steel pipe fittings, and will not be elaborated here.

[0033] Please see Figure 1 This invention provides a high-strength alloy electromagnetic shaping method, which utilizes the aforementioned high-strength alloy electromagnetic shaping component (see [link]). Figure 2The high-strength alloy electromagnetic straightening assembly includes a positioning mechanism 1 and an electromagnetic straightening mechanism 2. The positioning mechanism 1 includes a connected base 11 and a positioning column structure 12. The outer peripheral sidewall of the positioning column structure 12 is used to abut and fix the high-strength alloy pipe to be straightened. The electromagnetic straightening mechanism 2 includes a pulse power supply 21 and a straightening coil 22. The pulse power supply 21 is connected to the positive and negative poles of the straightening coil 22. The straightening coil 22 is connected to the base 11 and is sleeved on the positioning column structure 12 and spaced apart from the outer peripheral sidewall of the positioning column structure 12. The high-strength alloy electromagnetic straightening method includes the following steps: fixing the base 11 to the bottom of the hydraulic press and positioning it with screws; sleeve the high-strength alloy pipe to be straightened on the outside of the positioning column structure 12 and fix it with the positioning column structure 12; install the straightening coil 22 on the base 11 and fix it around the high-strength alloy pipe; and connect the electrodes of the straightening coil 22 to the pulse power supply 21. The hydraulic press is connected to the positioning column structure 12. The positioning column structure 12 expands to press against the inner wall of the high-strength alloy pipe, so that the high-strength alloy pipe expands to the preset diameter and the high-strength alloy pipe reaches the plastic deformation stage. The pulse power supply 21 is controlled to discharge to the shaping coil 22. The shaping coil 22 generates a pulse current and forms a transient high-strength magnetic field (peak magnetic flux density reaches 12T), and induces eddy currents on the surface of the high-strength alloy pipe. The eddy currents interact with the external magnetic field added by the shaping coil to generate a high-amplitude electromagnetic force. The electromagnetic force is initially concentrated on the outer surface of the high-strength alloy pipe, and then diffuses into the wall thickness of the pipe, effectively avoiding stress concentration and inducing the pipe to release the internal residual stress within milliseconds, thereby completing the electromagnetic shaping. The connection between the shaping coil 22 and the base 11 is disconnected and the shaping coil 22 is removed. Then the hydraulic press is lifted and the high-strength alloy pipe after shaping is taken out.

[0034] In the specific implementation process, firstly, the base 11 is fixed below the hydraulic press and positioned with screws to ensure the stability of the base 11; then, the high-strength alloy pipe to be shaped is sleeved on the outside of the positioning column structure 12. The gravity of the positioning column structure 12 ensures that the outer peripheral wall of the positioning column structure 12 is tightly abutted against the inner wall of the high-strength alloy pipe, ensuring the stability of the high-strength alloy pipe during processing; next, the shaping coil 22 is installed on the base 11 and arranged around the high-strength alloy pipe, and the electrodes of the shaping coil 22 are connected to the pulse power supply 21; then, the pressure rod of the hydraulic press is controlled to press down the positioning column structure 12, and the positioning column structure 12 expands to press against the inner wall of the high-strength alloy pipe, so that the high-strength alloy pipe expands to the preset diameter and reaches the plastic deformation stage. At this time, the high-strength alloy pipe... The residual stress inside the high-strength alloy tube exceeds the yield strength of the material, triggering dislocation movement and stress redistribution. Then, the control pulse power supply 21 discharges to the shaping coil 22, which generates a pulse current and forms a transient high-strength magnetic field (peak magnetic flux density reaches 12T), inducing eddy currents on the surface of the high-strength alloy tube. The eddy currents interact with the external magnetic field added by the shaping coil, generating a high-amplitude electromagnetic force. The electromagnetic force is initially concentrated on the outer surface of the high-strength alloy tube, and then diffuses into the interior of the tube wall, effectively avoiding stress concentration and inducing the tube to release internal residual stress within milliseconds, thus completing the electromagnetic shaping. Finally, the connection between the shaping coil 22 and the base 11 is disconnected, and the shaping coil 22 is removed. Then, the pressure rod of the hydraulic press is lifted, and the high-strength alloy tube after shaping is taken out. In this embodiment, after the high-strength alloy pipe is mechanically bulged, an additional electromagnetic force is generated on the surface of the pipe through a forming coil to eliminate most of the residual stress generated during the bulging process. After the high-strength alloy pipe is disassembled, its springback size is small, closer to the target size, and the error is small.

[0035] In one embodiment, please refer to Figure 2 The positioning mechanism 1 also includes multiple support rods 13, which are arranged around the periphery of the positioning column structure 12. One end of each support rod 13 is connected to the base 11, and the other end of each support rod 13 is connected to the shaping coil 22, so that the shaping coil 22 is installed according to specifications. The inner wall of the shaping coil 22 is evenly spaced from the outer periphery of the positioning column structure 12. The purpose of setting the support rods 13 in this embodiment is to enhance the structural stability of the shaping coil 22, ensuring that during the electromagnetic shaping process, the shaping coil 22 can stably generate electromagnetic induction with the steel pipe 3 to be shaped after being energized, driving the steel pipe 3 to undergo plastic shaping, and maintaining a uniform interval between the shaping coil 22 and the positioning column structure 12, thereby ensuring a uniform distribution of the magnetic field and improving the shaping accuracy.

[0036] In one embodiment, please refer to Figure 3The shaping coil 22 includes a first insulating ring 221, a second insulating ring 222, a coil frame 223, and an induction coil 224. The first insulating ring 221 and the second insulating ring 222 are connected to the axial ends of the coil frame 223, respectively. The induction coil 224 is wound around the coil frame 223, and its positive and negative terminals are connected to a pulse power supply 21. In this embodiment, the first insulating ring 221 and the second insulating ring 222 fix the position of the coil frame 223, preventing displacement or deformation of the induction coil 224 during operation, thereby ensuring that the induction coil 224 can stably generate a magnetic field. The coil frame 223 provides a supporting structure for the induction coil 224, allowing it to be tightly wound around the coil frame 223, increasing the inductance and magnetic field strength of the induction coil 224. After the induction coil 224 is wound around the coil frame 223, by connecting to the pulse power supply 21, it can generate a momentary strong magnetic field under the action of a pulse current, thereby achieving electromagnetic shaping of the steel pipe fitting 3.

[0037] The calibration coil 22 also includes a positive electrode 225 and a negative electrode 226. The first insulating ring 221 and the second insulating ring 222 have corresponding slots. The positive electrode 225 is secured in the slot of the first insulating ring 221, and the negative electrode 226 is secured in the slot of the second insulating ring 222. Both the positive electrode 225 and the negative electrode 226 are connected to the induction coil 224. Furthermore, the positive electrode 225 and the negative electrode 226 are respectively connected to the positive and negative terminals of the pulse power supply 21, so that the pulse power supply 21 provides input current to the induction coil 224.

[0038] In one embodiment, please refer to Figure 4 and Figure 5 The positioning column structure 12 includes multiple bulging support blocks 121, which are arranged circumferentially to form the positioning column structure 12. A drive slot 122 is formed between the inner walls of the multiple bulging support blocks 121, and one end of each of the multiple bulging support blocks 121 is radially connected to the base 11 along the drive slot 122. In this embodiment, by setting multiple bulging support blocks 121, the positioning column structure 12 can be bulged and adjusted according to steel pipe fittings 3 of different diameters, thereby achieving the fixation of steel pipe fittings 3 of different specifications. When it is necessary to correct pipe fittings of different diameters, by sliding the multiple bulging support blocks 121, the multiple bulging support blocks 121 can be moved closer or further apart, thereby adjusting the outer circumferential dimensions of the positioning column structure 12 to adapt to the inner diameter of the steel pipe fitting 3 to be corrected, thus achieving a stable fixation of the steel pipe fitting 3. In addition, the multiple expansion support blocks 121 are all radially connected to the base 11 along the drive slot 122. When the steel pipe 3 is abutted by the outer wall of the multiple expansion support blocks 121, the multiple expansion support blocks 121 can be driven to slide further away from each other, so that the steel pipe 3 can be initially expanded to the preset diameter. Subsequently, the electromagnetic expansion of the straightening coil 22 can improve the straightening efficiency of the steel pipe 3.

[0039] In one embodiment, please refer to Figure 5 and Figure 6 The end of the expansion support block 121 connected to the base 11 has a first arc-shaped groove 123 and a slide rail 129. The multiple first arc-shaped grooves 123 of the multiple expansion support blocks 121 are interconnected to form a first annular groove 124, and the first annular groove 124 is engaged with a first elastic ring 125. In this embodiment, each expansion support block 121 is provided with elastic support and constraint by the first elastic ring 125, ensuring that the expansion support block 121 can stably expand or contract radially during sliding, while preventing excessive deformation or displacement, thereby improving the stability and alignment accuracy of the entire device.

[0040] Please see Figure 6 The base 11 has a through hole 111 at its center. Multiple guide blocks 112 are arranged around the through hole 111, and a sliding groove 113 is formed between adjacent guide blocks 112 at intervals. The sliding groove 113 is arranged radially along the through hole 111. Multiple bulging support blocks 121 are sequentially slidably engaged with the multiple sliding grooves 113 via their respective bottom slide rails 129, allowing the multiple bulging support blocks 121 to slide closer together or further apart along the radial direction of the through hole 111.

[0041] Furthermore, the bulging support block 121 has a second arc-shaped groove 126 at the end away from the base 11. The multiple second arc-shaped grooves 126 of the multiple bulging support blocks 121 are interconnected to form a second annular groove 127, and the second annular groove 127 is engaged with a second elastic ring 128. In this embodiment, the function of the second elastic ring 128 is similar to that of the first elastic ring 125 described above. The second elastic ring 128 can further enhance the stability of the bulging support block 121, prevent the bulging support block 121 from undergoing local deformation or displacement during the bulging process, and ensure the uniform bulging of the steel pipe 3.

[0042] In one embodiment, please refer to Figure 5 The positioning mechanism 1 also includes a pressing member 14, which is slidably inserted into the drive slot 122 and can simultaneously press against multiple bulging support blocks 121 during sliding, thereby driving the multiple bulging support blocks 121 to slide away from each other. In this embodiment, the function of the pressing member 14 is to apply an outward pushing force to the multiple bulging support blocks 121 through its sliding movement, thereby realizing the bulging of the steel fitting. In actual operation, the pressing member 14 can slide towards the drive slot 122 under the drive of an external power device such as a hydraulic press, thereby pushing the multiple bulging support blocks 121 to slide outward, thereby realizing the initial bulging of the steel pipe fitting 3.

[0043] Further, please refer to Figure 5The pressing component 14 includes a central cone 141 and a connecting plate 142. One end of the central cone 141 is connected to the connecting plate 142, and the other end of the central cone 141 is slidably inserted into the drive slot 122. The connecting plate 142 is detachably connected to the pressure rod of the hydraulic press. In this embodiment, the central cone 141 is slidably inserted into the drive slot 122. In the direction of insertion, the cross-sectional area of ​​the central cone 141 decreases, making the central cone 141 approximately conical. During the sliding process towards the drive slot 122, the central cone 141 can more effectively convert its axial force into the radial expansion force of the expansion support block 121, thereby achieving uniform expansion of the steel pipe 3. The connecting plate 142 is mainly used to connect the pressing component 14 to the pressure rod of the hydraulic press. The pressure applied by the pressure rod of the hydraulic press drives the pressing component 14 to slide along the drive slot 122, thereby realizing the expansion operation. The detachable design of the connecting plate 142 facilitates the replacement of the pressing component 14 or other maintenance operations when needed.

[0044] In one embodiment, please refer to Figure 5 The outer peripheral sidewall of the central cone 141 is formed into a frustum shape, and the drive slot 122 is a frustum slot that is adapted to the outer peripheral sidewall of the central cone 141. In this embodiment, setting the outer peripheral sidewall of the central cone 141 into a frustum shape and setting the drive slot 122 as a frustum slot can increase the contact area between the central cone 141 and the drive slot 122, improve the force transmission efficiency, and at the same time prevent the central cone 141 from deflecting during sliding, thereby improving the stability of the bulging of the steel pipe fitting 3.

[0045] In one embodiment, please refer to Figure 5 The pressing component 14 also includes an epoxy block 143, which connects the central cone 141 and the connecting plate 142. In this embodiment, the epoxy block 143 serves to firmly connect the central cone 141 and the connecting plate 142 together, forming an integral pressing component 14 structure. The epoxy block 143 has good mechanical and adhesive properties, ensuring that the pressing component 14 will not loosen or break during operation, thereby ensuring the stable operation of the electromagnetic alignment assembly.

[0046] In one embodiment, an aluminum alloy pipe can be fitted over the steel pipe. When the shaping coil 22 is energized, the main body subjected to electromagnetic force changes from the steel pipe to the aluminum alloy pipe. The electromagnetic force on the aluminum alloy pipe acts on the steel pipe, indirectly shaping the steel pipe. This embodiment is suitable for shaping metal pipes with low conductivity, while the above embodiments are generally suitable for shaping metal pipes with high conductivity. Since the positioning column structure 12 and the pressing member 14 are both made of iron, they can still induce eddy currents of sufficient density. Therefore, the above embodiments can still shape metal pipes with low conductivity.

[0047] The structure of the high-strength alloy electromagnetic straightening assembly has been described in detail above. The steps of the high-strength alloy electromagnetic straightening method will be further broken down below:

[0048] (a) Pre-expansion preparation stage

[0049] Fixed base 11: Fix the base 11 to the bottom of the hydraulic press and position it with screws to ensure the stability of the base.

[0050] Install the positioning column structure 12: Connect the positioning column structure 12 to the base 11, and slide the bottom of the multiple bulging support blocks 121 of the positioning column structure 12 into the groove on the base 11.

[0051] Install rubber positioning rings: Install a first elastic ring 125 in the first annular groove 124 formed by multiple bulging support blocks 121, and install a second elastic ring 128 in the second annular groove 127 to ensure that the bulging support blocks 121 can slide back and forth stably during operation.

[0052] Placement of steel pipe fitting 3 and pressing center cone 141: The steel pipe fitting 3 is fitted onto the outside of multiple bulging support blocks 121, and simultaneously inserted into the center cone 141 along the drive slot 122 formed by the multiple bulging support blocks 121. Relying on the gravity of the center cone 141, it moves downwards, pushing the multiple bulging support blocks 121 into frictional contact with the inner wall of the steel pipe fitting 3, preventing axial displacement of the steel pipe fitting 3. At this point, the preparatory work for the pre-bulging stage is complete.

[0053] (II) Electromagnetic calibration preparation stage

[0054] Connecting support rod 13: Connect support rod 13 to base 11 (e.g., by screws) to ensure stable fixation of support rod 13.

[0055] Install the alignment coil 22: Install the alignment coil 22 on the support rod 13, and connect and fix the alignment coil 22 to the support rod 13; the inner wall of the alignment coil 22 and the outer peripheral side wall of the positioning column structure 12 should be arranged at equal and uniform intervals to ensure the uniform distribution of the magnetic field.

[0056] (III) Pre-expansion stage

[0057] Start the hydraulic press: Start the hydraulic press, and push the lower pressing component 14 (including the central cone 141 and the connecting plate 142) to slide along the drive slot 122 through the pressure rod of the hydraulic press.

[0058] Deformation of the bulging support blocks: Under the action of the hydraulic press, multiple bulging support blocks 121 undergo uniform radial plastic deformation under the constraint of the inner wall of the steel pipe 3. This plastic deformation causes the original residual stress in the steel pipe 3 to exceed the yield strength of the material, triggering dislocation movement and stress redistribution, causing the steel pipe 3 to bulge to the preset diameter and enter the plastic deformation stage. At this time, the hydraulic press is stopped from continuing to press down, and the pressing part 14 is kept in the current position. Thus, the pre-bulging stage is completed.

[0059] (iv) Electromagnetic calibration stage

[0060] Connect the pulse power supply: Connect the electrodes of the calibration coil 22 to the pulse power supply 21, ensuring a secure connection.

[0061] Pulse power supply discharge: Start the pulse power supply 21 to discharge to the shaping coil 22. The typical peak value of the pulse current is 10-50 kA and the rise time is 1-10 μs. The shaping coil 22 generates a transient high-strength magnetic field under the action of the pulse current.

[0062] Electromagnetic induction and shaping: A transient high-strength magnetic field (peak magnetic flux density up to 12T) induces eddy currents on the surface of the high-strength alloy pipe. The eddy currents interact with the external magnetic field added to the shaping coil to generate a high-amplitude electromagnetic force. The electromagnetic force is initially concentrated on the outer surface of the high-strength alloy pipe and then diffuses into the interior of the pipe wall thickness, effectively avoiding stress concentration and inducing the pipe to release internal residual stress within milliseconds, thereby completing the electromagnetic shaping.

[0063] (V) Final stage of correction

[0064] Raise the center cone 141: Use a hydraulic press to raise the center cone 141 so that the bulging support block 121 returns to its original position.

[0065] Remove the alignment coil: Disconnect the alignment coil 22 from the support rod 13 and remove the alignment coil 22.

[0066] Remove the steel pipe fitting: Push the bulging support block 121 inward to remove the steel pipe fitting after the alignment is completed. At this point, the entire alignment process is complete.

[0067] In this embodiment, the dimensional changes of the steel pipe at each stage of the experiment are shown in Table 1. The first embodiment, the second embodiment, and the third embodiment in Table 1 are steel pipes with different initial dimensions but the same material.

[0068] Table 1 (below) shows the radial dimension variation data of several steel pipe fittings with different initial dimensions under different experimental conditions:

[0069]

[0070] Table 1 above lists the dimensional data of three metal pipes with different initial dimensions at various experimental stages. It is evident that the dimensions of the same metal pipe change at different stages. It should be emphasized that the table only shows the use of a hydraulic press for pre-expansion forming, followed by direct removal of the metal pipe, which can be considered a comparative example of existing technology. The step of performing pre-expansion forming followed by electromagnetic straightening, and then removing the pipe, is the electromagnetic straightening method of this application.

[0071] Since unshaped metal pipes are non-standard and roughly elliptical in shape, they can be shaped into regular circles after straightening.

[0072] In the first embodiment, the initial dimensions of the pipe fitting before calibration were: shortest diameter 206mm, longest diameter 211mm, average diameter approximately 207mm, and roundness error 5mm. After pre-expansion using a hydraulic press, the dimensions of the pipe fitting upon removal were: shortest diameter 207.8mm, longest diameter 209.8mm, average diameter approximately 208.5mm, and roundness error reduced to 2mm. However, after pre-expansion using a hydraulic press followed immediately by electromagnetic calibration, the dimensions of the pipe fitting upon removal were: shortest diameter 210.1mm, longest diameter 210.5mm, average diameter approximately 210.3mm, and roundness error only 0.4mm. Therefore, after electromagnetic calibration, the roundness error of the pipe fitting was significantly reduced from the initial 5mm to 0.4mm, improving accuracy by 12.5 times, and the average diameter was also closer to the target size.

[0073] In the second embodiment, the initial dimensions of the pipe fitting before calibration were: shortest diameter 182mm, longest diameter 192mm, average diameter approximately 186mm, and roundness error 10mm. After pre-expansion using a hydraulic press, the dimensions of the pipe fitting upon removal were: shortest diameter 186.2mm, longest diameter 190.2mm, average diameter approximately 188mm, and roundness error reduced to 4mm. After pre-expansion using a hydraulic press followed by electromagnetic calibration, the dimensions of the pipe fitting upon removal were: shortest diameter 190.2mm, longest diameter 190.7mm, average diameter approximately 190.5mm, and roundness error only 0.5mm. This embodiment shows that electromagnetic calibration reduced the roundness error from the initial 10mm to 0.5mm, improving accuracy by 20 times, with a particularly significant effect.

[0074] In the third embodiment, the initial dimensions of the pipe before calibration were: shortest diameter 254mm, longest diameter 262mm, average diameter approximately 257mm, and roundness error 8mm. After pre-expansion using a hydraulic press, the dimensions of the removed pipe were: shortest diameter 256.6mm, longest diameter 260mm, average diameter approximately 258.5mm, and roundness error reduced to 3.4mm. After pre-expansion using a hydraulic press followed by electromagnetic calibration, the dimensions of the removed pipe were: shortest diameter 260.2mm, longest diameter 260.6mm, average diameter approximately 260.4mm, and roundness error only 0.4mm. In this embodiment, electromagnetic calibration reduced the roundness error from the initial 8mm to 0.4mm, improving accuracy by 20 times.

[0075] The data from the three embodiments above demonstrate that the electromagnetic straightening method of this application applies a pulsed magnetic field immediately after mechanical pre-expansion. This generates a high-amplitude electromagnetic force through the interaction of eddy currents and the applied magnetic field, effectively releasing residual stress within the pipe fitting within milliseconds. Compared to pipe fittings that only undergo mechanical pre-expansion, the roundness error of the pipe fitting after electromagnetic straightening is significantly reduced, from several millimeters to sub-millimeter levels (0.4-0.5 mm), and the average diameter is also closer to the target size. This data fully demonstrates the technical effect described in this application: that high-strength alloy pipe fittings, after disassembly, exhibit a small springback size closer to the target size with minimal error—this is indeed achievable, and the effect is highly significant.

[0076] To better understand this invention, the following is combined with... Figures 1 to 8 The technical solution of the present invention will be described in detail below:

[0077] In practical use, the steel pipe fitting 3 to be shaped is first placed on the positioning column structure 12 of the positioning mechanism 1. The central cone 141 slides under its own gravity, causing multiple expansion support blocks 121 to expand and slide against the inner wall of the steel pipe fitting 3, thus pre-fixing the steel pipe fitting 3 to be shaped, thereby firmly fixing the fitting on the positioning column structure 12. Then, the hydraulic press is controlled to press down the positioning column structure 12, and the positioning column structure 12 further expands to press against the inner wall of the steel pipe fitting 3, so that the steel pipe fitting 3 expands to the preset diameter and reaches the plastic deformation stage. Next, the pulse power supply 21 is activated, providing a pulse current to the shaping coil 22. The pulse power supply discharges to the shaping coil, which generates a pulse current and forms a transient high-intensity magnetic field (peak magnetic flux density reaches 12T), inducing eddy currents on the surface of the high-strength alloy pipe. The eddy currents interact with the external magnetic field added to the shaping coil, generating a high-amplitude electromagnetic force. The electromagnetic force is initially concentrated on the outer surface of the high-strength alloy pipe, and then diffuses into the interior of the pipe wall, effectively avoiding stress concentration and inducing the release of residual internal stress within milliseconds, thus completing the electromagnetic shaping. After shaping is completed, the pulse power supply 21 is turned off, the connection between the shaping coil 22 and the base 11 is disconnected, and the shaping coil 22 is removed. Then, the pressure rod of the hydraulic press is raised, and the shaped steel pipe 3 is taken out.

[0078] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A high-strength alloy electromagnetic shaping method, implemented using a high-strength alloy electromagnetic shaping assembly, characterized in that, The high-strength alloy electromagnetic straightening assembly includes a positioning mechanism and an electromagnetic straightening mechanism. The positioning mechanism includes a connected base and a positioning column structure. The outer peripheral sidewall of the positioning column structure is used to abut and fix the high-strength alloy pipe to be straightened. The electromagnetic straightening mechanism includes a pulse power supply and a straightening coil. The pulse power supply is connected to the positive and negative terminals of the straightening coil. The straightening coil is connected to the base. The straightening coil is sleeved on the positioning column structure and spaced apart from the outer peripheral sidewall of the positioning column structure. The high-strength alloy electromagnetic straightening method includes the following steps: Secure the base to the bottom of the hydraulic press and position it with screws; The high-strength alloy pipe fitting to be shaped is sleeved on the outside of the positioning post structure and fixed by the positioning post structure; The calibration coil is mounted and fixed on the base and set around the high-strength alloy tube. The electrodes of the calibration coil are connected to the pulse power supply. The hydraulic press's pressure rod presses down on the positioning column structure, which then expands to press against the inner wall of the high-strength alloy pipe, causing the high-strength alloy pipe to expand to a preset diameter and enter the plastic deformation stage. The control pulse power supply discharges to the correction coil, which generates a pulse current and forms a transient high-strength magnetic field. The transient high-strength magnetic field induces eddy currents on the surface of the high-strength alloy pipe. The eddy currents interact with the external magnetic field added to the correction coil to generate a high-amplitude electromagnetic force. The electromagnetic force is initially concentrated on the outer surface of the high-strength alloy pipe and then diffuses into the wall thickness of the pipe, thereby completing the electromagnetic correction. Disconnect the alignment coil from the base and remove the alignment coil. Then lift the hydraulic press lever and remove the high-strength alloy pipe after alignment.

2. The electromagnetic shaping method for high-strength alloys according to claim 1, characterized in that, The positioning mechanism also includes multiple support rods, which are arranged around the periphery of the positioning column structure. One end of each support rod is connected to the base, and the other end is connected to the calibration coil. The inner wall of the calibration coil is evenly spaced from the outer periphery of the positioning column structure.

3. The electromagnetic shaping method for high-strength alloys according to claim 2, characterized in that, The calibration coil includes a first insulating ring, a second insulating ring, a coil frame, and an induction coil. The first insulating ring and the second insulating ring are connected to the two ends of the coil frame respectively. The induction coil is wound around the coil frame, and the positive and negative terminals of the induction coil are connected to the pulse power supply.

4. The electromagnetic shaping method for high-strength alloys according to claim 1, characterized in that, The positioning mechanism also includes a plurality of bulging support blocks, which are arranged circumferentially to form the positioning column structure. A drive slot is formed between the inner walls of the plurality of bulging support blocks, and one end of each of the plurality of bulging support blocks is slidably connected to the base.

5. The electromagnetic shaping method for high-strength alloys according to claim 4, characterized in that, The end of the bulging support block connected to the base is provided with a first arc-shaped groove, and the multiple first arc-shaped grooves of the multiple bulging support blocks are connected to each other to form a first annular groove, and a first elastic ring is engaged in the first annular groove.

6. The electromagnetic shaping method for high-strength alloys according to claim 5, characterized in that, The positioning mechanism further includes a pressing member, which is slidably inserted into the drive slot and can press against the plurality of the bulging support blocks during sliding to drive the plurality of bulging support blocks to slide away from each other.

7. The electromagnetic shaping method for high-strength alloys according to claim 6, characterized in that, The pressing component includes a central cone and a connecting plate. One end of the central cone is connected to the connecting plate, and the other end of the central cone is slidably inserted into the drive slot. The connecting plate is detachably connected to the pressure rod of the hydraulic press.

8. The electromagnetic shaping method for high-strength alloys according to claim 7, characterized in that, The outer peripheral sidewall of the central cone forms a frustum shape, and the drive slot is a frustum slot that is adapted to the outer peripheral sidewall of the central cone.

9. The electromagnetic shaping method for high-strength alloys according to claim 7, characterized in that, The pressing component includes an epoxy block, which connects the central cone and the connecting plate.

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