Weak magnetic multi-bend elbow special-shaped recess electromagnetic positioning rubber bag forming die

Abstract

The invention discloses a weak magnetic multi-bend elbow special-shaped recess electromagnetic positioning rubber bag forming die, which is used for forming a special-shaped recess in the middle section of a bent pipe after a large-length weak magnetic material elbow pipe is bent and formed, and comprises a forming convex die, an oil-filled rubber bag and a limiting tire, the forming male die and limiting tire structure comprises a positioning electromagnet, and the oil filling rubber bag structure comprises an electromagnetic positioning piece. In the forming process, the structure position of the oil-filled rubber bag is controlled through electromagnetic positioning, and the special-shaped pit is formed through the oil-filled rubber bag and the forming male die. The problems that in the bent pipe special-shaped recess forming process, material flowing and stress distribution are difficult to be completely uniform, the recess shape is irregular or the thickness is inconsistent possibly, and an existing special-shaped recess forming process needs special equipment and a high-precision mold, so that the manufacturing cost is high, the machining preparation time is long, and the production efficiency is low are solved.

Description

Technical Field

[0001] This invention relates to the technology for forming irregular concave sections of bent pipes in the field of aircraft manufacturing, specifically a weak magnetic multi-bend bent pipe irregular concave electromagnetic positioning rubber bladder forming mold. Background Technology

[0002] Multi-bend tubing plays a crucial role in aircraft. It is primarily used for piping connections and layout optimization in internal aircraft systems such as fuel, hydraulic, and air conditioning systems. These components, through complex designs, meet space constraints and performance requirements, ensuring efficient and reliable fluid transport. Furthermore, multi-bend tubing reduces vibration and noise, improving overall flight comfort. In terms of lightweight design, they utilize high-strength materials, reducing weight while maintaining structural stability, meeting the high efficiency and safety requirements of aircraft. These characteristics make multi-bend tubing an indispensable component of modern aircraft, supporting the stable operation of systems.

[0003] As is well known, irregular recesses on multi-bend pipe components are a common and specialized design feature used to avoid spatial conflicts or mechanical interference with other components during aircraft assembly. This structure typically appears in complex-shaped piping systems, especially where the pipe needs to pass through other structural members, supports, or other pipes. These irregular recesses provide the necessary space for the multi-bend pipe, ensuring smooth passage or avoidance of surrounding fixed structures, supports, wiring, or other components during assembly. They are usually located at the bends in the pipe, allowing for flexible arrangement within a limited space through localized recesses or deformations, while avoiding collisions or friction with other components. Furthermore, this design helps reduce stress concentration during assembly and improves the overall system's installation efficiency and reliability. By optimizing these structural features, multi-bend pipes can be ensured to operate stably in the complex spatial environment inside aircraft, meeting the stringent requirements of the system for fluid transport, weight distribution, and space utilization.

[0004] Irregularly shaped recesses are typically achieved through localized deformation (such as stretching or compression), requiring concentrated force in specific areas while avoiding excessive deformation in other areas. During pipe bending, material flow and stress distribution are difficult to achieve perfectly uniformly, potentially leading to irregular recess shapes or inconsistent thicknesses. For thin-walled pipes, excessive deformation can cause material thinning or even breakage; while for thick-walled pipes, insufficient deformation may result in shallow depths. Irregularly shaped recesses typically have high dimensional accuracy requirements, especially in the aerospace field, where even minor deviations can lead to assembly interference or functional failure. Traditional stamping or bending equipment cannot meet the requirements for forming irregularly shaped recesses, necessitating specialized equipment (such as hydraulic presses, stretch forming equipment, etc.) and high-precision molds, resulting in high costs and design difficulties. Therefore, there is an urgent need for a simple-to-design, low-cost mold to achieve precise forming of irregularly shaped recesses in multi-bend pipes. Summary of the Invention

[0005] The purpose of this invention is to provide a weak magnetic multi-bend curved tube irregular concave electromagnetic positioning rubber bag forming mold to solve the problems in the existing forming methods of irregular concave tubes, such as the difficulty in achieving completely uniform material flow and stress distribution, which may lead to irregular concave shape or inconsistent thickness. In addition, the existing irregular concave tube forming process requires special equipment (such as hydraulic press, stretch forming equipment, etc.) and high-precision molds, resulting in high manufacturing costs, long processing preparation time and low production efficiency.

[0006] The technical solution of the present invention is as follows: The present invention provides a weak magnetic multi-bend tube irregular concave electromagnetic positioning rubber bladder forming mold, which is used to form a long weak magnetic material bend tube 1 after bending and forming an irregular concave 2 of the bend tube. The diameter D of this type of bend tube 1 is usually greater than 20mm; the mold includes: forming punch 3, oil-filled rubber bladder 4 and limiting tire 5. The forming punch 3 has a rectangular block structure and includes: a punch surface 6, a punch body 7, and a punch positioning electromagnet 8. The punch surface 6 matches the outer surface of the irregular recessed area 2 of the bent pipe. The punch body 7 is provided with a punch electromagnet mounting groove 9, the diameter of which is slightly larger than the diameter of the punch positioning electromagnet 8. The punch body 7 is provided with a punch electromagnet wire through hole 10. The punch positioning electromagnet 8 includes a punch coil 11 and a punch core 12. The core of the punch core 12 is cylindrical and wound with the punch coil 11. The punch core 12 is connected to a punch conical core block 13, and the top of the punch conical core block 13 is the punch electromagnetic positioning surface 14. The main body of the limiting tire 5 includes: a limiting surface 15, a limiting tire body 16, and a limiting tire positioning electromagnet 17; the limiting surface 15 matches the outer surface of the uniform cylindrical area of ​​the bent pipe 1, and the range of the limiting surface 15 must include the straight section where the concave part of the irregular shape 2 is located and the bending area of ​​the bent pipe 1, so as to restrict the movement of the bent pipe 1; the limiting tire body 16 is provided with a limiting tire electromagnet mounting groove 18, the diameter of the limiting tire electromagnet mounting groove 18 is slightly larger than the diameter of the limiting tire positioning electromagnet 17, and the limiting tire body 16 is provided with a limiting surface 17. The tire electromagnet wire passes through hole 19, and the two ends of the limiting tire body 16 are connected to the limiting bracket 20. The limiting bracket 20 must maintain the same direction as the bend 1. The limiting bracket 20 and the limiting tire body 16 are manufactured as a single unit. The limiting tire positioning electromagnet 17 includes a limiting tire coil 21 and a limiting tire core 22. The core of the limiting tire core 22 is cylindrical and is wound with the limiting tire coil 21. The limiting tire core 22 is connected to the limiting tire conical core block 23. The top of the limiting tire conical core block 23 is the limiting tire electromagnetic positioning surface 24. The oil-filled rubber bladder 4 includes a rubber bladder 25, a conduit 26, and an electromagnetic positioning plate 27. The rubber bladder 25 includes a rubber bladder body 28 and a rubber bladder forming surface 29. After the rubber bladder body 28 is filled with oil 30 and shaped, its diameter is slightly smaller than the inner diameter of the curved tube 1. The rubber bladder forming surface 29 is located at the top of the rubber bladder body 28. After being filled with oil 30 and shaped, it matches the shape of the irregular recess 2 area of ​​the curved tube 1. The conduit 26 is connected to the openings at both ends of the rubber bladder 25. A hydraulic device is used to fill the rubber bladder 25 with oil 30 through the conduit 26. The two ends of the conduit 26 need to extend beyond the two ends of the curved tube 1. There are two electromagnetic positioning plates 27, which are installed inside the rubber bladder 25, located at the center of the rubber bladder forming surface 29 and the center of the bottom surface of the rubber bladder body 28, respectively.

[0007] Furthermore, in the rubber bladder forming mold, the dimensions of the forming punch 3, the oil-filled rubber bladder 4, and the limiting tire 5 are set according to the dimensions of the bent pipe 1. The dimensions of the forming mold are set in the following ways: The distance between the edge of the irregular recess 2 area and the edges of the forming punch 3 and the rubber bladder body 28 at all circumferential positions is ≥30mm; if not, adjust the size of the forming punch 3 and the rubber bladder body 28. The size of the limiting tire 5 matches the outer surface of the bend tube 1. The range of the limiting surface 15 must include the bending area of ​​the bend tube 1, and the distance between the edge of the limiting surface 15 and the bending area of ​​the bend tube 1 at each position in the circumferential direction must be ≥30mm. If not, the size of the limiting tire 5 shall be adjusted.

[0008] Furthermore, the forming punch 3, punch surface 6, oil-filled rubber bladder 4, rubber bladder forming surface 29, and limiting surface 15 of the limiting jig 5 are set according to the surface features of the bent pipe 1, and the setting methods include: The punch surface 6 is set to offset the outer surface of the irregular recess 2 inward with a gap g. The rubber bladder forming surface 29 is set with the inner surface of the irregular recess 2 offset outward by the gap g; The limiting surface 15 is set to offset the uniform cylindrical region of the bend 1 outwards by the gap g; Where the gap g = (1.05~1.15)×δ, and δ is the material thickness of the bend 1.

[0009] Furthermore, the forming punch 3 and the limiting die 5 are made of non-magnetic materials, such as processable plastics; The material of the rubber bladder 25 should be a material with high strength in a low thickness state, such as butyl rubber; The punch positioning electromagnet 8 and the limit tire positioning electromagnet 17 are made of soft iron (industrial pure iron) for the punch core 12 and the limit tire core 22, and the punch coil 11 and the limit tire coil 21 are made of conductive materials such as copper and aluminum.

[0010] Furthermore, the punch surface 6 and the limiting surface 15 are mirror polished; The edges of the forming punch 3 and the limiting tire 5 are respectively set with R chamfers according to the tire body size.

[0011] Furthermore, the area S of the punch electromagnetic positioning surface 14 and the limiting tire electromagnetic positioning surface 24 is determined according to the material thickness δ of the bent tube 1, wherein the value of the area S is (2~3)×δ; the diameter of the electromagnetic positioning piece 27 in the oil-filled rubber bladder 4 is equal to the diameter of the punch electromagnetic positioning surface 14 and the limiting tire electromagnetic positioning surface 24.

[0012] Furthermore, the length of the conduit 26 is obtained based on the unfolded length of the bend 1 used, and the method of obtaining the length is as follows: By importing the theoretical shape of the bend 1 into the 3D modeling software, the central axis of the bend 1 is extracted, and the unfolded length l of the bend 1 is calculated using the unfolding function. The guide length L = l + (300~500) mm. There is a corresponding relationship between the diameter d of conduit 26 and the diameter D of bend 1, where d = D / 2; Project the theoretical surface edge of the bend 1 onto the conduit 26, and set a mark at the projected position of the conduit 26.

[0013] Furthermore, multiple rubber bladders 25 can be set in the oil-filled rubber bladder 4 structure, and the rubber bladders 25 can be connected by a conduit 26 to simultaneously form multiple irregular depressions 2 in the bend 1. Design the forming punch 3 corresponding to the irregular recess 2 according to the shape of the irregular recess 2; The irregular recess 2 and the forming punch 3 are marked with corresponding numbers. The forming punch 3 is located by the number during forming, which ensures that the position of the forming punch 3 can be quickly determined when in use. When the forming punch 3 is not in use, the punch electromagnet wire is used to bind and store it uniformly with steel wire through hole 14.

[0014] The beneficial effects of this application are as follows: 1) This invention provides a weak magnetic multi-bend tube irregular concave electromagnetic positioning rubber bladder forming mold. The shape can be flexibly adjusted through the oil-filled rubber bladder structure design. It is suitable for tubes of different materials and sizes and can accurately form multiple bends and irregular concaves to meet the needs of precision parts in aerospace, automotive and other fields. 2) This invention provides an electromagnetic positioning method for the forming of irregular concave tubes with weak magnetic multi-bends. The electromagnetic positioning technology achieves rapid and precise control, reduces the debugging time and cost of traditional molds, improves production efficiency, and ensures product quality consistency and reliability. It is especially suitable for mass production. 3) This invention provides a weak magnetic multi-bend tube irregular concave electromagnetic positioning rubber bag forming mold. When forming multi-specification irregular concave tubes, it is only necessary to replace the special punch corresponding to each irregular concave to perform multi-feature integrated forming, reducing the need to change molds, saving time and resources, thereby reducing costs. 4) This invention provides a weak magnetic multi-bend curved tube irregular concave electromagnetic positioning rubber bag forming mold. The tooling is made of weak magnetic or non-magnetic materials to prevent interference in sensitive environments and is suitable for more working environments. Attached Figure Description Figure 1 This is a schematic diagram of the structure of a pipe bending component. Figure 2 This is a schematic diagram of the use of an electromagnetic positioning rubber bladder forming mold. Figure 3 This is a schematic diagram of the assembly structure of the electromagnetic positioning rubber bladder forming mold. Figure 4 This is a schematic diagram of the forming punch structure. Figure 5 This is a schematic diagram of the limiting tire structure. Figure 6 This is a schematic diagram of the positioning electromagnet structure. Figure 7 This is a schematic diagram of an oil-filled rubber bladder. The numbers in the diagram are explained as follows: 1. Bend, 2. Irregular recess, 3. Forming punch, 4. Oil-filled rubber bladder, 5. Limiting tire, 6. Punch surface, 7. Punch body, 8. Punch positioning electromagnet, 9. Punch electromagnet mounting slot, 10. Punch electromagnet wire through hole, 11. Punch coil, 12. Punch core, 13. Punch conical core block, 14. Punch electromagnetic positioning surface, 15. Limiting surface, 16. Limiting tire body, 17. Limiting tire positioning electromagnet, 18. Limiting tire electromagnet mounting slot, 19. Limiting tire electromagnet wire through hole, 20. Limiting bracket, 21. Limiting tire coil, 22. Limiting tire core, 23. Limiting tire conical core block, 24. Limiting tire electromagnetic positioning surface, 25. Rubber bladder, 26. Conduit, 27. Electromagnetic positioning plate, 28. Rubber bladder body, 29. Rubber bladder forming surface, 30. Oil. Detailed Implementation

[0015] The present application will be further described in detail below with reference to the accompanying drawings of the embodiments.

[0016] See appendix Figure 1 The typical multi-bend tube 1 provided in the embodiment is shown in the figure. The tube 1 is made of a weakly magnetic material, with a thickness of about 1 mm and a length of about 1271 mm. Since the irregular recess requires a certain amount of space in the tube 1, the diameter D of the tube 1 is usually greater than 20 mm. The tube 1 is bent eight times in different directions. There is an irregular recess 2 near the middle of the tube 1. The lowest point of the irregular recess 2 is about 10 mm away from the tube body. Hundreds of this type of multi-bend tube 1 can exist on a single aircraft. The irregular recess 2 usually has high dimensional accuracy requirements, especially in the aerospace field, where even small deviations may lead to assembly interference or functional failure. The forming of the irregular recess 2 cannot be met by traditional stamping or bending equipment. Special equipment (such as hydraulic presses, stretch forming equipment, etc.) and high-precision molds are required, which is costly and difficult to design.

[0017] like Figures 2-7 As shown, the present invention provides a weak magnetic multi-bend tube irregular concave electromagnetic positioning rubber bladder forming mold, used to form a long weak magnetic material bend tube 1 and bend tube irregular concave 2 after bending; the mold structure includes: forming punch 3, oil-filled rubber bladder 4 and limiting tire 5. The forming punch 3 has a rectangular block structure and includes: a punch surface 6, a punch body 7, and a punch positioning electromagnet 8. The punch surface 6 matches the outer surface of the irregular recessed area 2 of the bent pipe. The punch body 7 is provided with a punch electromagnet mounting groove 9, the diameter of which is slightly larger than the diameter of the punch positioning electromagnet 8. The body is provided with a punch electromagnet wire through hole 10. The punch positioning electromagnet 8 includes a punch coil 11 and a punch core 12. The core of the punch core 12 is cylindrical and wound with the punch coil 11. The punch core 12 is connected to a punch conical core block 13, and the top of the punch conical core block 13 is the punch electromagnetic positioning surface 14. The main body of the limiting tire 5 includes: a limiting surface 15, a limiting tire body 16, and a limiting tire positioning electromagnet 17; the limiting surface 15 matches the outer surface of the uniform cylindrical area of ​​the bent pipe 1, and the range of the limiting surface 15 must include the straight section where the concave part of the irregular shape 2 is located and the bending area of ​​the bent pipe 1, so as to restrict the movement of the bent pipe 1; the limiting tire body 16 is provided with a limiting tire electromagnet mounting groove 18, the diameter of the limiting tire electromagnet mounting groove 18 is slightly larger than the diameter of the limiting tire positioning electromagnet 17, and the limiting tire body 16 is provided with a limiting surface 17. The tire electromagnet wire passes through hole 19, and the two ends of the limiting tire body 16 are connected to the limiting bracket 20. The limiting bracket 20 must maintain the same direction as the bend 1. The limiting bracket 20 and the limiting tire body 16 are manufactured as a single unit. The limiting tire positioning electromagnet 17 includes a limiting tire coil 21 and a limiting tire core 22. The core of the limiting tire core 22 is cylindrical and is wound with the limiting tire coil 21. The limiting tire core 22 is connected to the limiting tire conical core block 23. The top of the limiting tire conical core block 23 is the limiting tire electromagnetic positioning surface 24. The oil-filled rubber bladder 4 includes a rubber bladder 25, a conduit 26, and an electromagnetic positioning plate 27. The rubber bladder 25 includes a rubber bladder body 28 and a rubber bladder forming surface 29. After the rubber bladder body 28 is filled with oil 30 and shaped, its diameter is slightly smaller than the inner diameter of the curved tube 1. The rubber bladder forming surface 29 is located at the top of the rubber bladder body 28. After being filled with oil 30 and shaped, it matches the shape of the irregular recess 2 area of ​​the curved tube 1. The conduit 26 is connected to the openings at both ends of the rubber bladder 25. A hydraulic device is used to fill the rubber bladder 25 with oil 30 through the conduit 26. The two ends of the conduit 26 need to extend beyond the two ends of the curved tube 1. There are two electromagnetic positioning plates 27, which are installed inside the rubber bladder 25, located at the center of the rubber bladder forming surface 29 and the center of the bottom surface of the rubber bladder body 28, respectively.

[0018] Furthermore, in the rubber bladder forming mold, the dimensions of the forming punch 3, the oil-filled rubber bladder 4, and the limiting tire 5 are set according to the dimensions of the bent pipe 1. The dimensions of the forming mold are set in the following ways: The distance between the edge of the irregular recess 2 region and the edges of the forming punch 3 and the rubber bladder body 28 at various circumferential positions is ≥30mm; if not, the size of the forming punch 3 and the rubber bladder body 28 is adjusted to ensure that the material flow of the irregular recess 2 during the forming process does not exceed the limiting range of the forming punch 3 and the rubber bladder body 28. The range of the limiting surface 15 must include the bending area of ​​the bent tube 1, and the distance between the edge of the limiting surface 15 and the bending area of ​​the bent tube 1 at each position in the circumferential direction must be ≥30mm; otherwise, the size of the limiting jig 5 shall be adjusted so that the limiting jig 5 restricts the movement of the bent tube 1 during the forming process.

[0019] Furthermore, the forming punch 3, punch surface 6, oil-filled rubber bladder 4, rubber bladder forming surface 29, and limiting surface 15 of the limiting jig 5 are set according to the surface features of the bent pipe 1, and the setting methods include: The punch surface 6 is set to offset the outer surface of the irregular recess 2 inward with a gap g. The rubber bladder forming surface 29 is set with the inner surface of the irregular recess 2 offset outward by the gap g; The limiting surface 15 is set to offset the uniform cylindrical region of the bend 1 outwards by the gap g; Where the gap g = (1.05~1.15)×δ, and δ is the material thickness of the bend 1.

[0020] Furthermore, the forming punch 3 and the limiting die 5 are made of non-magnetic materials, such as processable plastics, to prevent electromagnetic interference in sensitive environments and to make them suitable for more working environments. The material of the rubber bladder 25 should be a material with high strength in a low thickness state, such as butyl rubber. Butyl rubber has excellent air tightness, aging resistance and high tear strength. It can provide sufficient strength in a thinner state and is relatively easy to process. At the same time, this material has good oil resistance and is suitable as a raw material for oil-filled rubber bladders. The punch positioning electromagnet 8 and the limit tire positioning electromagnet 17 are made of soft iron (industrial pure iron) for the punch core 12 and the limit tire core 22, and the punch coil 11 and the limit tire coil 21 are made of conductive materials such as copper and aluminum.

[0021] Furthermore, the punch surface 6 and the limiting surface 15 are mirror polished to prevent scratches and dents on the bent tube during the forming process; The edges of the forming punch 3 and the limiting tire 5 are respectively set with R chamfers according to the tire body size to prevent injury to operators during use.

[0022] Furthermore, the area S of the punch electromagnetic positioning surface 14 and the limiting tire electromagnetic positioning surface 24 is determined according to the material thickness δ of the bent tube 1, wherein the area S = (2~3)×δ; the diameter of the electromagnetic positioning piece 27 in the oil-filled rubber bladder 4 is equal to the diameter of the punch electromagnetic positioning surface 14 and the limiting tire electromagnetic positioning surface 24.

[0023] Furthermore, the length of the conduit 26 is obtained based on the unfolded length of the bend 1 used, and the method of obtaining the length is as follows: By importing the theoretical shape of the bend 1 into the 3D modeling software, the central axis of the bend 1 is extracted, and the unfolded length l of the bend 1 is calculated using the unfolding function. The length L of the conduit 26 is L = l + (300-500) mm. There is a corresponding relationship between the diameter d of the conduit 26 and the diameter D of the bend 1, where d = D / 2, to ensure that the oil 30 can pass smoothly through the conduit 26 and be injected into the rubber bladder 25; The theoretical surface edge of the bend 1 is projected onto the conduit 26, and a mark is set at the projected position of the conduit 26 to ensure that the position of the rubber bladder 25 can be initially determined, thereby improving the spatial accuracy of subsequent electromagnetic positioning.

[0024] Furthermore, multiple rubber bladders 25 can be set in the oil-filled rubber bladder 4 structure, and the rubber bladders 25 can be connected by a conduit 26 to simultaneously form multiple irregular depressions 2 in the bend 1. Design the forming punch 3 corresponding to the irregular recess 2 according to the shape of the irregular recess 2; The irregular recess 2 and the forming punch 3 are marked with corresponding numbers. During forming, the forming punch 3 is located by the number, which ensures that the position of the forming punch 3 can be quickly determined during use and reduces the cost of use. When the forming punch 3 is not in use, the punch electromagnet wire is used to bind and store it uniformly with steel wire through hole 14 to prevent the small pieces of forming punch 3 from being lost, which can significantly reduce tooling management costs.

[0025] The specific usage method of this mold is as follows: Step 1: Install the bend tube 1 at the corresponding position of the limiting tire 5. Place the oil-filled rubber bladder 4 in the bend tube 1 in the unfilled state. According to the marks at both ends of the guide tube 26, pull the guide tube 26 to move the rubber bladder 25 to the approximate position of the irregular concave area 2 to be formed. Step 2: Seal one end of the conduit 26 and use a hydraulic device to pre-fill the oil 30 through the conduit 26, so that the oil 30 fills about two-thirds of the volume of the rubber bladder 25, ensuring that the two electromagnetic positioning plates 27 are physically separated, so that the tire positioning electromagnet 17 will not attract and fix the two electromagnetic positioning plates 27 at the same time after it is opened, affecting the filling of oil 30 and the shaping of the rubber bladder 25. Step 3: Turn on the switch of the limiting tire positioning electromagnet 17 to position the electromagnetic positioning piece 27 in the oil-filled rubber bladder 4, and accurately lock the spatial position of the rubber bladder 25 in the irregular recess 2 area. Step 4: Use a hydraulic device to inflate the rubber bladder 4 with oil 30 to shape it, ensuring that the rubber bladder 25 is fully expanded and sealing the other end of the conduit 26. Step 5: Move the forming punch 3 to the approximate position of the irregular recess 2 area to be formed in the bent tube 1, and turn on the punch positioning electromagnet 8 to adjust and lock the spatial position of the forming punch 3 according to the electromagnetic positioning piece 27. Step 6 uses the forming punch 3 and the oil-filled rubber bladder 4 as male and female molds to form the irregular recess 2, so that the dimensional accuracy of the irregular recess 2 meets the requirements of the drawing.

Claims

1. A magnetic flux weakening multi-bend pipe special-shaped recess electromagnetic positioning rubber bladder forming die, characterized in that, The electromagnetic positioning rubber bag forming die is used for forming the special-shaped recess (2) of the bent pipe after the bending forming of the long-length weak magnetic material bent pipe (1); the die comprises a forming punch (3), an oil-filled rubber bag (4) and a limiting tire (5); The forming punch (3) is a cuboid block structure and comprises a punch profile (6), a punch tire body (7) and a punch positioning electromagnet (8); the punch profile (6) is matched with the outer shape of the area of the special-shaped recess (2) of the bent pipe; the punch tire body (7) is provided with a punch electromagnet mounting groove (9), the diameter of the punch electromagnet mounting groove (9) is slightly larger than the diameter of the punch positioning electromagnet (8), and the punch tire body (7) is provided with a punch electromagnet wire passing hole (10); the punch positioning electromagnet (8) comprises a punch coil (11) and a punch core (12), the core body of the punch core (12) is a cylindrical structure and is wound with the punch coil (11), the punch core (12) is connected with a punch conical core block (13), and the top end of the punch conical core block (13) is a punch electromagnetic positioning surface (14); The limiting tire (5) comprises a limiting profile (15), a limiting tire body (16) and a limiting tire positioning electromagnet (17); the limiting profile (15) is matched with the outer shape of the uniform cylindrical area of the bent pipe (1), the range of the limiting profile (15) needs to contain the straight line segment part of the special-shaped recess (2) and the bending area of the bent pipe (1) to limit the movement of the bent pipe (1); the limiting tire body (16) is provided with a limiting tire electromagnet mounting groove (18), the diameter of the limiting tire electromagnet mounting groove (18) is slightly larger than the diameter of the limiting tire positioning electromagnet (17), the limiting tire body (16) is provided with a limiting tire electromagnet wire passing hole (19), both ends of the limiting tire body (16) are connected with limiting supports (20), the limiting supports (20) need to keep the same trend as the bent pipe (1), and the limiting supports (20) are integrally manufactured with the limiting tire body (16); the limiting tire positioning electromagnet (17) comprises a limiting tire coil (21) and a limiting tire core (22), the core body of the limiting tire core (22) is a cylindrical structure and is wound with the limiting tire coil (21), the limiting tire core (22) is connected with a limiting tire conical core block (23), and the top end of the limiting tire conical core block (23) is a limiting tire electromagnetic positioning surface (24); The oil-filled rubber bag (4) comprises a rubber bag (25), a catheter (26) and an electromagnetic positioning sheet (27), the rubber bag (25) comprises a rubber bag body (28) and a rubber bag forming surface (29), the rubber bag body (28) is slightly smaller in diameter than the inner surface diameter of the elbow pipe (1) after being shaped by oil (30), and the rubber bag forming surface (29) is located at the top of the rubber bag body (28) and matches the inner surface of the area of the special-shaped recess (2) of the elbow pipe (1) after being shaped by oil (30); the catheter (26) is connected with the two ends of the rubber bag (25) in an open manner, a hydraulic device is used to fill oil (30) into the rubber bag (25) through the catheter (26), and the two ends of the catheter (26) need to be beyond the two ends of the elbow pipe (1); the electromagnetic positioning sheet (27) is two in number and is installed inside the rubber bag (25) and is respectively located at the center of the rubber bag forming surface (29) and the bottom surface of the rubber bag body (28).

2. A magnetic soft multi-bend pipe special-shaped recess electromagnetic positioning rubber bag forming die according to claim 1, characterized in that, In the rubber bag forming die, the sizes of the forming punch (3), the oil-filled rubber bag (4) and the limiting tire (5) are set according to the size of the elbow pipe (1), and the size setting mode of the forming die comprises: The distance between the edge of the special-shaped recess (2) area and the edge of the forming punch (3) and the rubber bag body (28) at each position in the circumferential direction is greater than or equal to 30 mm; if not, the sizes of the forming punch (3) and the rubber bag body (28) are adjusted. The range of the limiting shape surface (15) needs to contain the bending area of the elbow pipe (1), and the distance between the range edge of the limiting shape surface (15) and the bending area of the elbow pipe (1) at each position in the circumferential direction is greater than or equal to 30 mm; if not, the size of the limiting tire (5) is adjusted.

3. A magnetic soft multi-bend pipe special-shaped recess electromagnetic positioning rubber bag forming die according to claim 2, characterized in that, The punch shape surface (6) of the forming punch (3), the rubber bag forming surface (29) of the oil-filled rubber bag (4) and the limiting shape surface (15) of the limiting tire (5) are set according to the shape characteristics of the elbow pipe (1), and the setting mode comprises: The punch shape surface (6) is set with an inward offset gap g to the outer shape surface of the special-shaped recess (2); The rubber bag forming surface (29) is set with an outward offset gap g to the inner shape surface of the special-shaped recess (2); The limiting shape surface (15) is set with an outward offset gap g to the outer shape surface of the uniform cylindrical area of the elbow pipe (1); Wherein the gap g = (1.05-1.15) x δ, and δ is the material thickness of the elbow pipe (1).

4. The weak magnetic multi-bent elbow pipe special-shaped recess electromagnetic positioning rubber bag forming die according to claim 1, 2 or 3, characterized in that: The materials of the forming punch (3) and the limiting tire (5) are selected to be non-magnetic materials; The material of the rubber bag (25) is selected to be a material with high strength in a low thickness state; The materials of the punch core (12) and the limiting tire core (22) in the punch positioning electromagnet (8) and the limiting tire positioning electromagnet (17) are selected to be soft iron, and the materials of the punch coil (11) and the limiting tire coil (21) are selected to be conductive materials.

5. A magnetic multi-bend pipe-shaped recessed electromagnetic positioning rubber bag forming mold according to claim 1, 2, 3, characterized in that, The punch shape surface (6) and the limiting shape surface (15) are mirror polished; The edge edges of the forming punch (3) and the limiting tire (5) are respectively provided with R chamfers according to the tire body size.

6. A magnetic soft multi-bend pipe special-shaped recessed electromagnetic positioning rubber bladder forming mold according to claim 1, characterized in that, The area S of the punch electromagnetic positioning surface (14) and the limiting electromagnetic positioning surface (24) is determined according to the material thickness δ of the elbow pipe (1), wherein the value of the area S is (2-3)×δ; The diameter of the electromagnetic positioning sheet (27) in the oil-filled rubber bag (4) is equal to the diameter of the punch electromagnetic positioning surface (14) and the limiting electromagnetic positioning surface (24).

7. A magnetic soft multi-bend pipe special-shaped recessed electromagnetic positioning rubber bladder forming mold according to claim 1, characterized in that, The length of the guide pipe (26) is obtained according to the development length of the elbow pipe (1) used, and the acquisition method is: By introducing the theoretical surface of the elbow pipe (1) into the three-dimensional modeling software, the axis of the elbow pipe (1) is extracted, and the development length (l) of the elbow pipe (1) is calculated by using the development function. The length of the guide pipe L=l+(300-500)mm; The diameter d of the guide pipe (26) has a corresponding relationship with the diameter D of the elbow pipe (1), wherein d=D / 2; The edge of the theoretical surface of the elbow pipe (1) is projected to the guide pipe (26), and a mark is set at the projected position of the guide pipe (26).

8. A magnetic soft multi-bend pipe special-shaped recess electromagnetic positioning rubber bag forming die according to claim 1, characterized in that, By setting multiple rubber bags (25) in the structure of the oil-filled rubber bag (4), the rubber bags (25) are connected through the guide pipe (26) to simultaneously form multiple special-shaped recesses (2) of the elbow pipe (1); According to the special-shaped recess (2) surface, the corresponding forming punch (3) of the special-shaped recess (2) is designed; The special-shaped recess (2) and the corresponding number of the forming punch (3) are sprayed, and the forming punch (3) is positioned by the number during forming to ensure that the position of the forming punch (3) is quickly determined during use; In the unused state, the forming punch (3) is uniformly bound and saved by using the punch electromagnet lead wire through hole (14) by using a steel wire.

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