A metal pipe fitting straightening device and a straightening method thereof

Abstract

The application discloses a metal pipe fitting shape correcting device and a shape correcting method thereof, and relates to the technical field of metal forming manufacturing. The metal pipe fitting shape correcting device comprises a pre-expanding assembly and an electromagnetic driving assembly. The pre-expanding assembly comprises a base, an elastic pressing-down piece and a plurality of expanding support blocks. The plurality of expanding support blocks are arranged along the circumferential direction and are formed with driving slots. One end of each of the plurality of expanding support blocks is slidably connected to the base, and the other end is slidably inserted into the elastic pressing-down piece through the driving slots. When the elastic pressing-down piece slides towards the driving slots, the plurality of expanding support blocks can slide away from each other along the radial direction. The electromagnetic driving assembly comprises an electromagnetic driving piece and a driving coil which are connected to each other. The electromagnetic driving piece is connected to the elastic pressing-down piece. By adopting the structure that the pre-expanding assembly and the electromagnetic driving assembly are combined, the application solves the problems of high energy consumption and low efficiency caused by the fact that the metal shape correcting device in the prior art relies on large heating equipment.

Description

Technical Field

[0001] This invention relates to the field of metal forming and manufacturing technology, and specifically to a metal pipe fitting straightening device and its straightening method. Background Technology

[0002] In modern high-end equipment manufacturing, metal pipes (such as copper pipes and stainless steel pipes) are widely used due to their excellent performance, but their high-precision forming has always been a technical challenge in the industry. Currently, the high-precision forming of some metal pipes mainly relies on high-temperature forming technology. High-temperature forming technology reduces the springback of metal pipe materials through a high-temperature environment, thereby improving the forming accuracy of metal pipes.

[0003] However, existing metal shaping equipment requires heating the metal pipes to a high temperature during the shaping process in order to reduce the strength of the metal pipes, increase their plasticity, and reduce shape distortion caused by springback during the forming process. This requires large heating equipment, which results in high energy consumption and a greater reliance on manual or mechanical force. This is not only inefficient but also has a significant impact on the health of the workers. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a metal pipe fitting straightening device and its straightening method. This invention solves the technical problem that existing metal straightening equipment relies on large heating equipment when straightening metal pipe fittings, which leads to high energy consumption and a greater reliance on human or mechanical force, resulting in low efficiency and significant impact on the health of workers.

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

[0006] In a first aspect, the present invention provides a metal pipe fitting straightening device, comprising:

[0007] A pre-expansion assembly includes a base, an elastic pressing member, and a plurality of expansion support blocks. The plurality of expansion support blocks are arranged circumferentially and form drive slots. One end of each expansion support block is slidably connected to the base, and the other end of each expansion support block is slidably inserted into the elastic pressing member through the drive slot. When the elastic pressing member slides toward the drive slot, it can drive the plurality of expansion support blocks to slide radially away from each other.

[0008] An electromagnetic drive assembly includes an electromagnetic drive element and a drive coil. The drive coil has a central hole, and the central axis of the electromagnetic drive element passes through the center of the central hole. The electromagnetic drive element is connected to the elastic pressing element. When the drive coil is energized, the electromagnetic drive element can generate an external magnetic field and simultaneously generate eddy currents on the electromagnetic drive element. The external magnetic field and the eddy currents form an electromagnetic repulsion force to drive the electromagnetic drive element upward. The electromagnetic drive element drives the elastic pressing element to accumulate elastic potential energy. When the elastic pressing element releases the elastic potential energy, it can drive multiple bulging support blocks to slide radially away from each other.

[0009] In some embodiments, the elastic pressing member includes a pressing member and an elastic member, one side of the pressing member is slidably inserted into the drive slot and connected to the electromagnetic drive member, and the opposite side of the pressing member is connected to the elastic member.

[0010] In some embodiments, the pressing member includes a pressure plate and a central cone, one side of the pressure plate is connected to the central cone, the other side of the pressure plate is connected to the elastic member, the central cone is slidably inserted into the drive slot, and the cross-sectional area of ​​the central cone decreases in the direction from the elastic member to the pressure plate.

[0011] 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 frustum of the central cone.

[0012] In some embodiments, the elastic element is a polyurethane pad, and the area of ​​the polyurethane pad is larger than the area of ​​the pressure plate.

[0013] 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.

[0014] In some embodiments, the end of the bulging support block near the elastic pressing member is provided with a second arc-shaped groove, and the multiple second arc-shaped grooves of the multiple bulging support blocks are connected to each other to form a second annular groove, and the second annular groove is engaged with a second elastic ring.

[0015] In some embodiments, the drive coil is located on the side of the base opposite to the elastic pressing member, and the electromagnetic drive assembly further includes a positive electrode and a negative electrode disposed on the drive coil.

[0016] In some embodiments, one end of the electromagnetic drive member away from the drive coil passes through the base and extends into the drive slot, where it is threadedly connected to the elastic pressing member.

[0017] Secondly, the present invention also provides a method for straightening metal pipe fittings, which is implemented using the aforementioned metal pipe fitting straightening device. The method for straightening metal pipe fittings includes the following steps:

[0018] The base is installed and fixed to the lower base plate of the hydraulic press to complete the fixing of the metal pipe straightening device;

[0019] Multiple expansion support blocks are slidably installed. The metal pipe to be processed is sleeved on the outer wall of the multiple expansion support blocks. The elastic pressing component is moved a preset distance toward the drive slot to drive the multiple expansion support blocks to initially slide and expand to pre-fix the metal pipe and prevent the metal pipe from displacing along its axial direction.

[0020] Start the hydraulic press and apply axial pressure to the side of the elastic pressing member facing away from the expansion support block. The elastic pressing member is inserted into the drive slot and moves a preset distance, causing multiple expansion support blocks to slide and expand, increasing the diameter of the metal pipe to a preset diameter and holding it for a preset time.

[0021] Connect the electromagnetic drive component to the elastic pressing component and place the drive coil thereon;

[0022] The drive coil is connected to a pulse power supply and discharged. The electromagnetic induction force generated by the drive coil is used to straighten the metal pipe and make it meet the required dimensional accuracy and shape requirements.

[0023] Compared with existing technologies, the metal pipe straightening device provided by this invention effectively solves the problems of high energy consumption, low efficiency, and adverse effects on operator health caused by the reliance on large heating equipment in existing metal straightening equipment by adopting a structure combining a pre-expansion component and an electromagnetic drive component. Specifically, the metal pipe to be processed can first be fitted onto the outer wall of multiple expansion support blocks. The pre-expansion component, through the gravity of the elastic pressing component, axially compresses the multiple expansion support blocks to drive them to radially slide and expand. The multiple expansion support blocks abut against the metal pipe to pre-fix it. Then, the pressure rod of the hydraulic press is used to press down the elastic pressing component, driving the multiple expansion support blocks to expand and press against the inner wall of the metal pipe, pre-expanding the metal pipe to a preset size. Then, the drive coil is energized to generate a pulse current. Using the principle of electromagnetic induction, eddy currents are induced in the electromagnetic drive component. The eddy currents interact with the external magnetic field generated by the drive coil to form an electromagnetic repulsion force. Since the drive coil is stationary, this electromagnetic repulsion force will drive the electromagnetic drive component to move towards the elastic pressing component. After being squeezed to a certain extent, the elastic pressing component accumulates elastic potential energy. The elastic pressing component will convert the elastic potential energy stored inside it into the function of moving downward, and drive the expansion support block to provide secondary support and shaping for the metal tube. This allows the metal tube to release residual stress and complete the shaping, thereby achieving precise shaping of the metal tube. The shaping task can be completed efficiently without high-temperature heating. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the metal pipe straightening device provided in one embodiment of the present invention;

[0025] Figure 2 This is a structural schematic diagram of the metal pipe straightening device provided in an embodiment of the present invention from another perspective;

[0026] Figure 3 This is a schematic diagram of the base of the metal pipe straightening device provided in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the structure of the central cone provided in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the structure of the metal pipe straightening device provided in this embodiment of the invention after the elastic pressing component has been removed;

[0029] Figure 6 This is a schematic diagram of the pulse current waveform input to the drive coil provided by the pulse power supply in an embodiment of the present invention;

[0030] Figure 7 This is a schematic diagram of the structure of the bulging support block provided in an embodiment of the present invention. Detailed Implementation

[0031] 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.

[0032] To address the technical problems of existing metal straightening equipment that relies on large heating devices for straightening metal pipes, resulting in high energy consumption, high dependence on manual or mechanical force, low efficiency, and significant health risks for workers, this invention provides a metal pipe straightening device and method. This device can apply high-rate, short-duration pulse loads to metal pipes to achieve precise straightening, efficiently completing the straightening task without the need for high-temperature heating.

[0033] It should be noted that the metal pipe fitting straightening device described in this invention is used for, but not limited to, copper pipes, etc. For ease of explanation, this invention only uses the application of the metal pipe fitting straightening device to copper pipes as an example. The principle of the metal pipe fitting straightening device applied to other types of equipment is essentially the same as that applied to copper pipes, and will not be described in detail here.

[0034] Please see Figure 1 and Figure 2 , Figure 1This is a schematic diagram of the structure of a metal pipe straightening device in one embodiment of the present invention. The metal pipe straightening device includes a pre-expansion component and an electromagnetic drive component 2. The pre-expansion component includes a base 11, an elastic pressing component 12, and a plurality of expansion support blocks 13. The plurality of expansion support blocks 13 are arranged along the circumferential direction and form a drive slot 14. One end of each of the plurality of expansion support blocks 13 is slidably connected to the base 11, and the other end of each of the plurality of expansion support blocks 13 is slidably inserted into the elastic pressing component 12 through the drive slot 14. When the elastic pressing component 12 slides toward the drive slot 14, it can drive the plurality of expansion support blocks 13 to slide away from each other radially. The electromagnetic drive assembly 2 includes an electromagnetic drive component 21 and a drive coil 22. The drive coil 22 has a central hole. The central axis of the electromagnetic drive component 21 passes through the center of the central hole. The electromagnetic drive component 21 is connected to the elastic pressing component 12. When the drive coil 22 is energized, the electromagnetic drive component 21 can generate an external magnetic field and simultaneously generate eddy currents on the electromagnetic drive component 21. The external magnetic field and the eddy currents form an electromagnetic repulsion force to drive the electromagnetic drive component 21 to rise. The electromagnetic drive component 21 drives the elastic pressing component 12 to accumulate elastic potential energy. When the elastic pressing component 12 releases the elastic potential energy, it can drive multiple bulging support blocks 13 to slide away from each other radially.

[0035] A through hole 111 is provided in the center of the base 11, through which the electromagnetic drive component 21 passes, so that the electromagnetic drive component 21 can be inserted into the drive slot 14 and connected to the elastic pressing component 12. Multiple guide blocks 112 are arranged around the through hole 111 on the base 11, and a sliding groove 113 is formed between adjacent guide blocks 112. A slide rail 138 is provided at the bottom of the bulging support block 13. Figure 7 (As shown), the groove 113 is arranged radially along the through hole 111. Multiple bulging support blocks 13 are sequentially slidably engaged with the multiple grooves 113 via their respective slide rails 138, so that the multiple bulging support blocks 13 can slide closer or further away along the radial direction of the through hole 111.

[0036] In practical implementation, the metal pipe fitting straightening device achieves efficient straightening through the coordinated operation of the pre-expansion component and the electromagnetic drive component 2. First, the metal pipe fitting 3 to be straightened is placed on multiple expansion support blocks 13. The multiple expansion support blocks 13 in the pre-expansion component are evenly arranged along the circumferential direction to form a drive slot 14, and are slidably connected to the elastic pressing component 12 through the drive slot 14. The base 11 can be fixed to the hydraulic press. The elastic pressing member 12 can be located on the same vertical line as the pressure rod of the hydraulic press. When working, the hydraulic press is started and the pressure rod of the hydraulic press presses down on the elastic pressing member 12. The elastic pressing member 12 slides into the drive slot 14. The outer wall of the elastic pressing member 12 can simultaneously press against multiple expansion support blocks 13, driving the multiple expansion support blocks 13 to slide outward radially to perform preliminary expansion treatment on the metal pipe 3 (copper pipe). The diameter of the metal pipe 3 can be monitored in real time using measuring tools. When the diameter of the metal pipe 3 reaches the preset value, the movement of the elastic pressing member 12 is stopped immediately, and the elastic pressing member 12 is controlled to stop in the current position for a preset time to complete the preliminary shaping of the metal pipe 3.

[0037] Subsequently, for the electromagnetic calibration of metal pipe 3, the drive coil 22 is first connected to the pulse power supply, and the pulse power supply discharges to the drive coil 22. Please refer to the waveform diagram of the current flowing through the drive coil 22 at this time. Figure 6 The horizontal axis represents time (in milliseconds), and the vertical axis represents current (in kiloamperes). The pulse capacitor of the pulse power supply releases a large current (typical peak 10-50 kA, rise time 1-10 μs) to the drive coil 22, generating a high-frequency changing strong pulsed magnetic field in a very short time. According to Faraday's law of electromagnetic induction, this changing magnetic field induces eddy currents on the surface of the electromagnetic drive component 21. By inducing a sufficient density of eddy currents on the surface of the electromagnetic drive component 21, and simultaneously generating an external magnetic field in the drive coil 22, the eddy currents and the external magnetic field of the drive coil 22 interact to form an electromagnetic repulsion force. Since the drive coil 22 is fixed, this electromagnetic repulsion force drives the electromagnetic drive component 21 to move towards the elastic pressing component 12, acting on the elastic pressing component 12. When the elastic pressing member 12 moves upward under the electromagnetic force, the top of the elastic pressing member 12 is pressed against the pressure rod of the hydraulic press. At this time, the elastic pressing member 12 will accumulate a certain elastic force. After the elastic pressing member 12 is compressed to a certain extent, the elastic pressing member 12 will convert the elastic potential energy stored in it into the function of moving downward, and drive the expansion support block 13 to perform secondary support and shaping on the metal tube 3, so that the metal tube 3 releases residual stress and completes the shaping.

[0038] In one embodiment, please refer to Figure 2The elastic pressing member 12 includes a pressing member 121 and an elastic member 122. One side of the pressing member 121 is slidably inserted into the drive slot 14 and connected to the electromagnetic drive member 21, while the opposite side of the pressing member 121 is connected to the elastic member 122. In this embodiment, one end of the pressing member 121 is used to insert into the drive slot 14 to simultaneously press against multiple bulging support blocks 13 under the drive of the hydraulic press. The multiple bulging support blocks 13 can stably expand and contract radially. In addition, the end of the pressing member 121 inserted into the drive slot 14 is used to connect to the electromagnetic drive member 21 so that when the electromagnetic drive member 21 moves upward under electromagnetic repulsion, it can drive the pressing member 121 to move upward. The pressing member 121 drives the top of the elastic member 122 to be pressed against the pressure rod of the hydraulic press, thereby accumulating elastic potential energy in the elastic member 122. When the elastic potential energy of the elastic element 122 accumulates to a certain extent, it is converted into the function of downward movement, driving the pressing element 121 to move toward the drive slot 14. The pressing element 121 then drives multiple bulging support blocks 13 to generate secondary support and shaping on the metal tube 3.

[0039] Further, please refer to Figure 2 The elastic element 122 is a polyurethane pad, which has good elasticity and wear resistance, and can stably accumulate and release elastic potential energy during the movement of the elastic pressing element 12. At the same time, the polyurethane pad has a large area, which can evenly distribute the force between it and the pressing element 121.

[0040] Further, please refer to Figure 2 The pressing member 121 includes a pressure plate 123 and a central cone 124. One side of the pressure plate 123 is connected to the central cone 124, and the other side of the pressure plate 123 is connected to the elastic member 122. The central cone 124 is slidably inserted into the drive slot 14. In the direction from the elastic member 122 to the pressure plate 123, the cross-sectional area of ​​the central cone 124 decreases, so the central cone 124 is conical. During the sliding process towards the drive slot 14, the central cone 124 can more effectively convert its axial force into the radial expansion force of the expansion support block 13, thereby achieving uniform expansion of the metal tube 3. At the same time, the end of the central cone 124 inserted into the drive slot 14 is connected to the electromagnetic drive member 21 (the electromagnetic drive member 21 passes through the base 11 and extends into the drive slot 14, threadedly connecting to the central cone 124), so that when the electromagnetic drive member 21 moves upward, it can drive the central cone 124 to move upward, thereby the pressing member 121 moves towards the elastic member 122 to compress the elastic member 122 and accumulate elastic potential energy. The specific connection method between the center cone 124 and the electromagnetic drive component 21 is not limited, such as snap-fit, integral molding or threaded connection, etc. Threaded connection is preferred. In this embodiment, the center cone 124 has a threaded hole 137 at the bottom, and the threaded hole 137 is threadedly connected to the electromagnetic drive component 21, which is convenient for disassembly and assembly.

[0041] In addition, the elastic element 122 is a polyurethane pad, which is detachably connected to the pressure plate 123 by screws, making it easy to disassemble and replace. The area of ​​the polyurethane pad is larger than that of the pressure plate 123, so that the polyurethane pad can fully receive the force of the pressure plate 123 and convert it into elastic potential energy.

[0042] In one embodiment, please refer to Figure 2 The outer peripheral sidewall of the central cone 124 is formed into a frustum shape, and the drive slot 14 is a frustum slot that is adapted to the frustum outer peripheral sidewall of the central cone 124. In this embodiment, setting the outer peripheral sidewall of the central cone 124 into a frustum shape and setting the drive slot 14 as a frustum slot can increase the contact area between the central cone 124 and the drive slot 14, improve the force transmission efficiency, and at the same time prevent the central cone 124 from deflecting during sliding, ensuring the stability of the bulging process.

[0043] It is important to emphasize that when the electromagnetic drive component 21 drives the central cone 124 upward, it briefly disengages from the bulging support block 13, and then, under the elastic potential energy of the elastic component 122, it presses against the bulging support block 13 again. During this process, the entire time from the initial upward movement of the central cone 124 to its downward fixation is approximately 2.5 ms. The metal tube will fall a short distance, about 2-3 mm, which has almost no impact on the re-shaping effect of the bulging support block 13. Therefore, the time spent in this process is very short, and the downward movement of the central cone 124 creates an instantaneous force on the bulging support block 13, allowing the bulging support block 13 to further bulge the metal tube.

[0044] In one embodiment, please refer to Figure 2 The end of the expansion support block 13 connected to the base 11 has a first arc-shaped groove 131. The multiple first arc-shaped grooves 131 of the multiple expansion support blocks 13 are interconnected to form a first annular groove 133. The first annular groove 133 is engaged with a first elastic ring 134. In this embodiment, the first elastic ring 134 provides elastic support and constraint for the expansion support block 13, ensuring that the expansion support block 13 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.

[0045] In one embodiment, please refer to Figure 2The expansion support block 13 has a second arc-shaped groove 132 at its end near the elastic pressing member 12. Multiple second arc-shaped grooves 132 of the expansion support blocks 13 are interconnected to form a second annular groove 135, which is engaged with a second elastic ring 136. In this embodiment, by providing the second elastic ring 136, the stability of the expansion support block 13 can be further enhanced, preventing local deformation or displacement of the expansion support block 13 during the expansion process, and ensuring uniform expansion of the metal pipe 3.

[0046] In one embodiment, please refer to Figure 2 The drive coil 22 is located on the side of the base 11 facing away from the elastic pressing member 12. The electromagnetic drive assembly 2 also includes a positive electrode 221 and a negative electrode 222 disposed on the drive coil 22. In this embodiment, the positive electrode 221 and the negative electrode 222 disposed on the drive coil 22 are used to connect to an external pulse power supply so that the external pulse power supply can generate a stable pulse current in the drive coil 22 when it is working, thereby inducing eddy currents in the metal tube 3 and realizing electromagnetic induction correction.

[0047] Secondly, the present invention also provides a method for straightening metal pipe fittings, which is implemented using the aforementioned metal pipe fitting straightening device. The method for straightening metal pipe fittings includes the following steps:

[0048] (1) Pre-expansion preparation stage:

[0049] a. Fix the base 11 to the lower base plate of the hydraulic press with screws to complete the installation and fixing of the metal pipe straightening device;

[0050] b. Connect the pre-expansion device to the base 11, and slide multiple expansion support blocks 13 into the base 11 along multiple guide rails in sequence;

[0051] c. The first annular groove 133 and the second annular groove 135 formed by the multiple bulging support blocks 13 respectively engage the first elastic ring 134 and the second elastic ring 136 to pre-fix the multiple bulging support blocks 13.

[0052] d. Fit the metal pipe 3 onto the outer wall of the multiple expansion support blocks 13, and at the same time lower the central cone 124 along the inner wall of the expansion support block 13. Relying on the gravity of the central cone 124, the central cone 124 moves down and pushes the multiple expansion support blocks 13 to rub against the inner wall of the metal pipe 3, preventing the metal pipe 3 from axially displacing, thus completing the pre-expansion stage preparation work.

[0053] (2) Pre-expansion stage:

[0054] a. Start the hydraulic press and gradually apply axial downward pressure to the elastic pressing component 12 (polyurethane pad), while monitoring the diameter of the metal pipe 3 in real time;

[0055] b. After expanding the diameter of the metal pipe 3 to the preset diameter under quasi-static conditions, immediately stop the hydraulic press pressing action and maintain it for about five minutes, so that the metal pipe 3 undergoes uniform radial plastic deformation under the constraint of the expansion support block 13. This deformation causes the original residual stress to exceed the yield strength of the material, triggering dislocation movement and stress redistribution, thus completing the pre-expansion stage.

[0056] (3) Electromagnetic calibration preparation stage:

[0057] a. Connect the electromagnetic drive component 21 of the electromagnetic drive assembly 2 to the center cone 124 via a thread;

[0058] b. Place the drive coil 22 below the electromagnetic drive component 21 and connect it to complete the preparation work for the electromagnetic calibration stage.

[0059] (4) Electromagnetic calibration stage:

[0060] a. Connect the positive electrode 221 and negative electrode 222 of the drive coil 22 to the pulse power supply;

[0061] b. After the pulse power supply discharges, the generated pulse current passes through the drive coil 22. The drive coil 22 and the electromagnetic drive component 21 generate electromagnetic induction, causing eddy currents of sufficient density to be induced on the surface of the electromagnetic drive component 21. The eddy currents interact with the external magnetic field applied by the drive coil 22, exerting a force (which can be understood as a repulsive force) on the electromagnetic drive component 21. The electromagnetic drive component 21 drives the elastic pressing component 12 to rise. When the elastic pressing component 12 moves upward under the electromagnetic force, the support of the bulging support block 13 on the metal tube 3 will decrease for a certain period of time. Since the top of the elastic pressing component 12 is pressed against by the pressure rod of the hydraulic press, the elastic pressing component 12 will accumulate a certain amount of elastic force when it moves upward. After the elastic pressing component 12 is compressed to a certain extent, the elastic pressing component 12 will convert the elastic potential energy stored inside it into the function of downward movement, and drive the bulging support block 13 to provide secondary support and shaping for the metal tube 3, so that the metal tube 3 releases residual stress and completes the shaping.

[0062] (5) Correction completion stage:

[0063] a. The hydraulic press raises the pressure rod, disconnects the connection between the electromagnetic drive component 21 and the center cone 124, removes the center cone 124, and removes the drive coil 22;

[0064] b. Push the multiple bulging support blocks 13 to slide closer together, remove the metal pipe 3 after the correction is completed, and complete the entire correction process.

[0065] Table 1 (below) shows the dimensional changes of several metal tubular components with different initial dimensions during the experiment:

[0066]

[0067] As shown in Table 1 above, this application verifies the actual effect of the metal pipe fitting straightening device through three embodiments in specific implementations. In the first embodiment, the initial state of the un-straightened pipe fitting is an irregular ellipse, with a minimum diameter of 206mm, a maximum diameter of 211mm, an average diameter of approximately 207mm, and a roundness error of 5mm. After pre-expansion to 211mm by a hydraulic press, during the electromagnetic straightening stage, when the central cone rises and detaches from the expansion support block under the action of electromagnetic force, the pipe fitting diameter shrinks slightly to 210.8mm. Subsequently, during the rebound and downward pressing process of the elastic element's potential energy release, the diameter recovers to 211.1mm. The final size is actually 0.1mm larger than that of the pre-expansion stage, showing a rebound compensation effect. In the second embodiment, for pipe fittings with larger roundness errors (shortest 182mm, longest 192mm, error 10mm), the pre-expansion target is set at 191mm. During the electromagnetic action stage, the diameter decreases slightly from 191mm to 190.9mm, and after rebound, it reaches 191.2mm, also achieving overshoot compensation. The third embodiment processes a large-sized pipe with an average diameter of 257mm and a roundness error of 8mm. After pre-expansion to 261mm, the diameter is 260.8mm during the electromagnetic action stage, and stabilizes at 261.1mm after springback. All three embodiments show the same change pattern of "pre-expansion → electromagnetic shrinkage → elastic rebound overshoot".

[0068] The above data fully demonstrates the technical effect of the "pre-expansion + electromagnetic drive" synergistic shaping technique of this application. First, in the pre-expansion stage, the diameter of the pipe is expanded to the preset value by quasi-static loading with a hydraulic press and held for about five minutes, causing uniform plastic deformation of the pipe and effectively releasing the original residual stress. In all three embodiments, the roundness error is controlled within 1mm (the final diameter fluctuation range is within 0.3mm), which significantly improves the roundness of the pipe. Second, in the electromagnetic shaping stage, the electromagnetic induction force generated by the pulse current drives the elastic pressing component to complete the cycle of "rapid rise - elastic energy storage - instantaneous rebound". The pipe is subjected to secondary support shaping using a short-term pulse load of 2.5ms. The data shows that the diameter after rebound is 0.2-0.3mm larger than that in the electromagnetic action stage, which accurately compensates for the elastic recovery of the material and makes the final size stable near the preset diameter (deviation ≤0.1mm). Finally, high-precision shaping can be achieved without high-temperature heating throughout the process, avoiding the high energy consumption and occupational health risks of traditional thermoforming processes. At the same time, the high-speed response characteristics (millisecond level) of electromagnetic drive greatly improve the shaping efficiency. The three embodiments cover a pipe diameter range of 182-262mm, verifying the adaptability of the device to pipe fittings of different specifications.

[0069] In summary, the experimental data clearly demonstrate that this application achieves efficient and precise shaping of metal pipe fittings at room temperature through the synergistic effect of mechanical pre-expansion and electromagnetic pulse, fully achieving the technical effects of reducing energy consumption, improving efficiency, and protecting the health of operators as described in the instruction manual.

[0070] 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 metal pipe fitting straightening device, characterized in that, include: A pre-expansion assembly includes a base, an elastic pressing member, and a plurality of expansion support blocks. The plurality of expansion support blocks are arranged circumferentially and form drive slots. One end of each expansion support block is slidably connected to the base, and the other end of each expansion support block is slidably inserted into the elastic pressing member through the drive slot. When the elastic pressing member slides toward the drive slot, it can drive the plurality of expansion support blocks to slide radially away from each other. An electromagnetic drive assembly includes an electromagnetic drive element and a drive coil. The drive coil has a central hole, and the central axis of the electromagnetic drive element passes through the center of the central hole. The electromagnetic drive element is connected to the elastic pressing element. When the drive coil is energized, it generates an external magnetic field and simultaneously creates eddy currents on the electromagnetic drive element. The external magnetic field and the eddy currents create an electromagnetic repulsion force, driving the electromagnetic drive element to rise. Since the top of the elastic pressing element is held against the pressure rod of the hydraulic press, the electromagnetic drive element drives the elastic pressing element to accumulate elastic potential energy. When the elastic pressing element releases its elastic potential energy, it drives multiple bulging support blocks to slide radially away from each other and causes the bulging support blocks to provide secondary support and shaping for the metal tube.

2. The metal pipe fitting straightening device according to claim 1, characterized in that, The elastic pressing member includes a pressing member and an elastic member. One side of the pressing member is slidably inserted into the drive slot and connected to the electromagnetic drive member, and the other side of the pressing member is connected to the elastic member.

3. The metal pipe fitting straightening device according to claim 2, characterized in that, The pressing member includes a pressure plate and a central cone. One side of the pressure plate is connected to the central cone, and the other side of the pressure plate is connected to the elastic member. The central cone is slidably inserted into the drive slot. In the direction from the elastic member to the pressure plate, the cross-sectional area of ​​the central cone decreases.

4. The metal pipe fitting straightening device according to claim 3, 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 frustum of the central cone.

5. The metal pipe fitting straightening device according to claim 3, characterized in that, The elastic element is a polyurethane pad, and the area of ​​the polyurethane pad is larger than the area of ​​the pressure plate.

6. The metal pipe fitting straightening device according to claim 1, 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.

7. The metal pipe fitting straightening device according to claim 1, characterized in that, The expansion support block has a second arc-shaped groove at its end near the elastic pressing member. Multiple second arc-shaped grooves of multiple expansion support blocks are connected to each other to form a second annular groove, and a second elastic ring is engaged in the second annular groove.

8. The metal pipe fitting straightening device according to claim 1, characterized in that, The drive coil is located on the side of the base facing away from the elastic pressing member, and the electromagnetic drive assembly also includes a positive electrode and a negative electrode on the drive coil.

9. The metal pipe fitting straightening device according to claim 1, characterized in that, The end of the electromagnetic drive component away from the drive coil passes through the base and extends into the drive slot, where it is threadedly connected to the elastic pressing component.

10. A method for straightening metal pipe fittings, implemented using the metal pipe fitting straightening device as described in any one of claims 1-9, characterized in that, The method for straightening metal pipe fittings includes the following steps: The base is installed and fixed to the lower base plate of the hydraulic press to complete the fixing of the metal pipe straightening device; Multiple expansion support blocks are slidably installed. The metal pipe to be processed is sleeved on the outer wall of the multiple expansion support blocks. The elastic pressing component is moved a preset distance toward the drive slot to drive the multiple expansion support blocks to initially slide and expand to pre-fix the metal pipe and prevent the metal pipe from displacing along its axial direction. Start the hydraulic press and apply axial pressure to the side of the elastic pressing member facing away from the expansion support block. The elastic pressing member is inserted into the drive slot and moves a preset distance, causing multiple expansion support blocks to slide and expand, increasing the diameter of the metal pipe to a preset diameter and holding it for a preset time. Connect the electromagnetic drive component to the elastic pressing component and place the drive coil thereon; The drive coil is connected to a pulse power supply and discharged. The electromagnetic induction force generated by the drive coil is used to straighten the metal pipe and make it meet the required dimensional accuracy and shape requirements.

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