Apparatus for forming metal pipe fittings

Abstract

The application provides a device for metal pipe forming. The device for metal pipe forming comprises a upsetting-extruding die and a soft die bulging die. The upsetting-extruding die comprises an upper upsetting-extruding insert assembly and a lower upsetting-extruding insert assembly, a first accommodating space for accommodating a metal pipe to be processed is formed between the upper upsetting-extruding insert assembly and the lower upsetting-extruding insert assembly, and a preforming structure is arranged on each of the upper upsetting-extruding insert assembly and the lower upsetting-extruding insert assembly. The soft die bulging die comprises an upper soft die insert assembly and a lower soft die insert assembly, a second accommodating space for accommodating the metal pipe to be processed is formed between the upper soft die insert assembly and the lower soft die insert assembly, and the upper soft die insert assembly is provided with a soft die structure. The problem that the wall thickness is seriously thinned and the uniformity is poor due to small round angle and large deformation in the bulging area of the metal pipe in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of metal pipe manufacturing, and more specifically, to an apparatus for forming metal pipes. Background Technology

[0002] Metal pipe fittings, as a basic component of the manufacturing industry, cover multiple categories such as carbon steel pipe fittings and stainless steel pipe fittings. With their excellent physical and processing properties, they play a key role in many fields and have broad prospects driven by the demand for new energy and carbon neutrality.

[0003] However, the research and application of manufacturing technology for metal pipe fittings also face several challenges. For example, in the bulging process of metal pipe fittings, there are issues such as poor thickness uniformity in the deformed area and severe thinning in the rounded corner area (e.g., Figure 1 As shown, this leads to problems such as decreased strength and even cracking and scrapping. In the existing technology, metal pipe forming, especially in the field of bulging, often reduces wall thickness by axial feeding. However, this method cannot effectively control the thinning and wall thickness uniformity, especially for pipe structures with large deformation and small fillet radius.

[0004] There is currently no effective solution to the aforementioned technical problems. Summary of the Invention

[0005] The main objective of this invention is to provide an apparatus for forming metal pipe fittings, so as to solve the problem in the prior art that the wall thickness of the bulging area of ​​metal pipe fittings is severely reduced and the uniformity is poor due to the small radius of the corners and the large amount of deformation.

[0006] To achieve the above objectives, according to one aspect of the present invention, an apparatus for forming metal pipe fittings is provided, comprising: an upsetting die and a soft die forming die; the upsetting die includes an upper upsetting insert assembly and a lower upsetting insert assembly, a first receiving space for receiving the metal pipe fitting to be processed is formed between the upper and lower upsetting insert assemblies, and a pre-forming structure is provided on both the upper and lower upsetting insert assemblies, the pre-forming structure being used to extrude the metal pipe fitting so that a portion of the sidewall of the metal pipe fitting protrudes outward toward the radial direction of the metal pipe fitting to form a first target structure; the soft die forming die includes an upper soft die forming die and a lower soft die forming die forming a ... A second receiving space for accommodating a metal tube to be processed is formed between the upper soft mold insert assembly and the lower soft mold insert assembly. The upper soft mold insert assembly is provided with a soft mold structure. The upper soft mold insert assembly has a first processing position that moves toward the lower soft mold insert assembly to process the metal tube to form a first target structure, and a first clearance position that moves away from the lower soft mold insert assembly. When the upper soft mold insert assembly is in the first processing position, at least part of the soft mold structure is filled into the metal tube, and the first target structure is bulged until a second target structure is formed.

[0007] Furthermore, the upper upsetting insert assembly has a second processing position that moves toward the lower upsetting insert assembly to process the metal tube, and the upper upsetting insert assembly has a second clearance position away from the lower upsetting insert assembly.

[0008] Furthermore, the preformed structure includes a first annular clearance groove, and the lower upsetting insert assembly includes: a lower upsetting base plate, which is disposed opposite to the upper upsetting insert assembly; an upsetting insert die, which is disposed on the upper surface of the lower upsetting base plate, and a first through hole is provided in the middle of the die, and a first through hole is provided on the surface of the lower upsetting base plate opposite to the first through hole; and a first ejection mechanism, which passes through the first through hole and is disposed within the first through hole. A first receiving cavity is formed between the top surface of an ejector mechanism and the wall of a first through hole for accommodating at least a portion of a metal tube, and the first ejector mechanism is movably arranged along the axial direction of the first through hole to eject the metal tube located in the first receiving cavity; wherein, a first receiving space is formed between the first ejector mechanism, the upsetting insert die and the upper upsetting insert assembly, and a first annular clearance groove for processing and forming a first target structure is provided on the side wall of the first through hole.

[0009] Furthermore, the upsetting insert die includes: an upsetting die body, a first through hole in the middle of the upsetting die body, the first through hole including a large diameter section and a small diameter section, the large diameter section being disposed on the side facing the upper upsetting insert assembly, a first annular clearance groove being disposed at the transition connection between the large diameter section and the small diameter section, and during the processing of the metal pipe, part of the metal pipe is located in the small diameter section, and part of the end of the upper upsetting insert assembly extends into the large diameter section to cooperate with the first annular clearance groove to process and form the metal pipe.

[0010] Furthermore, the preformed structure includes a second annular clearance groove, and the upper upsetting insert assembly includes: an upper upsetting base plate, which is disposed opposite to a lower upsetting base plate, and the upsetting insert die is located between the upper and lower upsetting base plates; an upper die insert, the first end of which is connected to the upper upsetting base plate, and the second end of which extends toward one side of the upsetting insert die, and the second end of which is provided with a second annular clearance groove; and a first punch, the first end of which is connected to the upper upsetting base plate, and the second end of which is provided with a second annular clearance groove. The die extends toward one side of the upsetting insert, and the insert on the die is arranged along the circumference of the first punch. The first punch can drive the insert on the die to a second working position and a second clearance position. When the first punch is in the second working position, part of the insert on the die extends into the large diameter section, and part of the first punch extends into the metal pipe. The second annular clearance groove cooperates with the first annular clearance groove to process the metal pipe so that part of the metal pipe is deformed into the first annular clearance groove and the second annular clearance groove until the first target structure is formed.

[0011] Furthermore, a limiting step is provided on the surface of the first punch. The height of the limiting step in the axial direction of the first punch is greater than the height of the lower end of the insert on the die in the axial direction of the first punch. The inner sidewall of the insert on the die, a portion of the surface of the first punch, and the limiting step form a gap for the sidewall of the metal tube to pass through.

[0012] Furthermore, the upper upsetting insert assembly includes: a first fixing plate, which is disposed outside the first punch, and forms a first limiting cavity between the first fixing plate, the first punch, and the upper upsetting base plate, and one end of the insert on the die is movably disposed in the first limiting cavity; and a first elastic member, which is disposed in the first limiting cavity, and is located between the top of the insert on the die and the first fixing plate.

[0013] Further, the lower soft mold insert assembly includes: a lower soft mold base plate, which is disposed opposite to the upper soft mold insert assembly; a soft mold cavity, which is connected to the lower soft mold base plate, the lower soft mold base plate having a second through hole, and a second through hole being provided on the surface of the lower soft mold base plate opposite to the second through hole; a second ejection mechanism, which is disposed in the second through hole through the second through hole, the top surface of the second ejection mechanism and the hole wall of the second through hole forming a first receiving cavity for accommodating at least a portion of the metal pipe, and the second ejection mechanism is movably disposed along the axial direction of the second through hole to eject the metal pipe located in the first receiving cavity; wherein, the second ejection mechanism, the soft mold cavity, and the upper upsetting insert assembly form a second receiving space, and a third annular clearance groove for processing and forming a second target structure is provided on the side wall of the second through hole.

[0014] Furthermore, the second ejection mechanism includes: a top plate, a relief recess provided in the middle of the top plate, and an annular gap formed between the outer peripheral surface of the top plate and the wall of the second through hole for the lower end sidewall of the metal pipe to pass through.

[0015] Further, the upper soft mold insert assembly includes: an upper soft mold base plate, which is disposed opposite to a lower soft mold base plate; a second punch, the first end of which is connected to the upper soft mold base plate, and the second end of which extends toward the lower soft mold base plate; a second fixing plate, which is connected to the upper soft mold base plate and located outside the second punch, and a second limiting space is formed between the second fixing plate and the upper soft mold base plate; an upper soft mold insert, one end of which is movably disposed within the second limiting space, and the other end of which is provided with a fourth annular clearance groove for processing and forming a second target structure; a second elastic member, which is disposed within the second limiting space and located between the end of the upper soft mold insert and the upper soft mold base plate; and an expanding soft mold, which is connected to the upper soft mold base plate via a connecting rod, the expanding soft mold being located at the end of the second punch, and the expanding soft mold being movable relative to the connecting rod, the connecting rod being located inside the second punch.

[0016] By applying the technical solution of this invention, the wall thickness of metal pipe fittings in areas with small radii and large deformation is precisely controlled through the synergistic action of an upsetting die and a soft die forming die. In the initial forming stage, the metal pipe fitting is clamped in the first receiving space. Through the synergistic extrusion of the upper and lower upsetting insert assemblies, the pre-formed structure applies directional plastic deformation to specific areas of the metal pipe fitting, causing the pipe wall to bulge radially outward in a localized manner, forming a first target structure with a preliminary outline. This process achieves pre-distribution of material in high deformation areas, effectively mitigating the risk of excessive thinning due to insufficient local material during subsequent forming. Subsequently, the metal pipe fitting is transferred to the second receiving space of the soft die forming die, and the upper soft die insert assembly can be moved to the first processing position, where the soft die structure is mounted. Under pressure, the material is fully embedded into the inner cavity of the metal tube and conforms to the inner wall of the first target structure. A uniform internal pressure bulging force is applied to the deformation area, causing the first target structure to further extend and form the final second target structure. Due to the flexible conformability of the soft mold structure, it can conform to complex internal surfaces and achieve multi-point synchronous bulging, avoiding local stress concentration in rigid molds. Simultaneously, combined with material control of the pre-formed structure, it significantly improves the problem of severe and uneven wall thickness reduction in the bulging area. Once bulging is complete, the upper soft mold insert assembly can retract to the first clearance position, facilitating workpiece removal and subsequent processing. This two-stage forming synergy mechanism, consisting of pre-forming extrusion and flexible internal bulging, directly solves the defects of uneven wall thickness and excessive thinning caused by small fillet radius and large deformation in existing technologies, achieving improved thickness uniformity and stable forming quality of metal tubes during complex surface forming processes. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 This diagram shows a comparison of the forming structures of the bulging region in pipe fittings processed using existing technologies.

[0019] Figure 2 A schematic diagram of the forming structure of the bulging region of the pipe fitting structure according to the processing technology of the present invention is shown;

[0020] Figure 3 A schematic diagram of the deformation region structure of a pipe fitting processed by the metal pipe fitting forming equipment according to the present invention is shown.

[0021] Figure 4 A schematic diagram of a first embodiment of an apparatus for forming metal tubes according to the present invention is shown.

[0022] Figure 5 A schematic diagram of a second embodiment of the apparatus for forming metal tubes according to the present invention is shown;

[0023] Figure 6 A schematic diagram of a third embodiment of an apparatus for forming metal tubes according to the present invention is shown;

[0024] Figure 7 A schematic diagram of a fourth embodiment of an apparatus for forming metal tubes according to the present invention is shown.

[0025] The above figures include the following reference numerals:

[0026] 10. Upsetting die; 11. Upper upsetting insert assembly; 111. Upper upsetting base plate; 112. Upper insert of the die cavity; 113. Second annular clearance groove; 114. First punch; 1140. Limiting step;

[0027] 12. Lower upsetting insert assembly; 121. Lower upsetting base plate; 122. Upsetting insert die cavity; 1220. Upsetting die body; 1221. Large diameter section; 1222. Small diameter section; 123. First ejection mechanism; 124. First annular clearance groove; 125. First fixing plate; 1251. First limiting cavity; 126. First elastic element;

[0028] 13. Pre-formed structure;

[0029] 20. Metal pipe fittings;

[0030] 30. Soft mold bulging die; 31. Upper soft mold insert assembly; 310. Soft mold structure; 311. Upper soft mold base plate; 312. Second punch; 313. Second fixing plate; 314. Upper soft mold insert; 315. Fourth annular clearance groove; 316. Second elastic element; 317. Bulging soft mold; 318. Connecting rod; 32. Lower soft mold insert assembly; 321. Lower soft mold base plate; 322. Soft mold cavity; 3221. Large diameter section; 3222. Small diameter section; 323. Second ejection mechanism; 3231. Ejector plate; 324. Third annular clearance groove;

[0031] 40. Guide post;

[0032] 50. Guide tube. Detailed Implementation

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0036] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art. In the drawings, for clarity, the thickness of layers and regions may be exaggerated, and the same reference numerals are used to denote the same devices, and therefore their description will be omitted.

[0037] Combination Figures 1 to 7 As shown in the figure, according to a specific embodiment of this application, an apparatus for forming metal tubes is provided.

[0038] Specifically, such as Figure 4 and Figure 5 As shown, the equipment for forming metal pipe fittings includes an upsetting die 10 and a soft die bulging die 30. The upsetting die 10 includes an upper upsetting insert assembly 11 and a lower upsetting insert assembly 12. A first receiving space for accommodating the metal pipe fitting 20 to be processed is formed between the upper upsetting insert assembly 11 and the lower upsetting insert assembly 12. Pre-forming structures 13 are provided on both the upper upsetting insert assembly 11 and the lower upsetting insert assembly 12. The pre-forming structures 13 are used to extrude the metal pipe fitting 20 so that a portion of the sidewall of the metal pipe fitting 20 protrudes outward in the radial direction of the metal pipe fitting 20 to form a first target structure (e.g., Figure 2(The structure shown in step two). The soft mold bulging die 30 includes an upper soft mold insert assembly 31 and a lower soft mold insert assembly 32. A second receiving space for accommodating the metal tube 20 to be processed is formed between the upper soft mold insert assembly 31 and the lower soft mold insert assembly 32. The upper soft mold insert assembly 31 is provided with a soft mold structure 310. The upper soft mold insert assembly 31 has a first processing position that moves towards the lower soft mold insert assembly 32 to process the metal tube 20 forming the first target structure, and a first clearance position that moves away from the lower soft mold insert assembly 32. When the upper soft mold insert assembly 31 is in the first processing position, at least a portion of the soft mold structure 310 fills the metal tube 20, and the first target structure is bulged until a second target structure (such as...) is formed. Figure 2 Step three, and Figure 3 (The structure shown).

[0039] By applying the technical solution of this embodiment, the wall thickness of the metal tube in areas with small radii and large deformation is precisely controlled through the synergistic action of the upsetting die 10 and the soft die forming die 30. In the initial forming stage, the metal tube 20 is clamped in the first receiving space. Through the synergistic extrusion of the upper upsetting insert assembly 11 and the lower upsetting insert assembly 12, the pre-formed structure 13 applies directional plastic deformation to specific areas of the metal tube 20, causing the tube wall to bulge radially outward in a localized manner, forming a first target structure with a preliminary outline. This process achieves pre-distribution of material in high deformation areas, effectively mitigating the risk of excessive thinning due to insufficient local material during subsequent forming. Subsequently, the metal tube 20 is transferred to the second receiving space of the soft die forming die 30, and the upper soft die insert assembly 31 can be moved to the first processing position, where the soft die is set. Under pressure, structure 310 is fully embedded into the inner cavity of the metal tube 20 and conforms to the inner wall of the first target structure, applying uniform internal pressure bulging force to the deformation area, causing the first target structure to further extend and form the final second target structure. Due to the flexible conforming characteristics of the soft mold structure 310, it can conform to complex inner surfaces and achieve multi-point synchronous bulging, avoiding local stress concentration in rigid molds. At the same time, in conjunction with the material control of the pre-forming structure 13, it significantly improves the problem of severe and uneven wall thickness reduction in the bulging area. When the bulging is completed, the upper soft mold insert assembly 31 can retract to the first clearance position, facilitating the removal of the workpiece and the next processing. This two-stage forming collaborative mechanism composed of pre-forming extrusion and flexible internal bulging directly solves the defects of uneven wall thickness and excessive thinning caused by small fillet radius and large deformation in the prior art, realizing the improvement of thickness uniformity and the stability of forming quality of metal tubes in the process of forming complex surfaces.

[0040] It should be noted that the first target structure is an intermediate form formed after upsetting and extrusion, with an outer contour that is a trapezoidal bulge with relatively large rounded corners and a slightly lower height; it is not the final product. The second target structure is the final product contour after soft mold bulging, characterized by small rounded corners, steep transitions, and precise dimensions. Both are products of the process stage, not final parts; their existence is a technical means to control thinning, not the product itself.

[0041] Specifically, the upper upsetting insert assembly 11 has a second processing position that moves toward the lower upsetting insert assembly 12 to process the metal tube 20, and the upper upsetting insert assembly 11 has a second clearance position away from the lower upsetting insert assembly 12.

[0042] The second processing position and the second clearance position enable the upper upsetting insert assembly 11 to actively detach from the lower upsetting insert assembly 12 after completing the pre-forming extrusion of the metal tube 20 and forming the first target structure. This releases the clamping constraint on the metal tube 20, thereby avoiding demolding difficulties caused by interference between the upper upsetting insert assembly 11 and the metal tube 20 or the lower upsetting insert assembly 12 during the subsequent soft mold bulging process. Furthermore, the setting of the second clearance position, combined with the structure of the first accommodating space, ensures that the metal tube 20 has sufficient freedom and space when transitioning from the upsetting process to the soft mold bulging process. This allows the soft mold bulging die 30 to smoothly enter the second accommodating space and perform the bulging operation, significantly improving the continuity and reliability of the overall processing flow while reducing the risk of die wear and tube surface damage.

[0043] Specifically, such as Figure 6 and Figure 7 As shown, the preformed structure 13 includes a first annular clearance groove 124, and the lower upsetting insert assembly 12 includes a lower upsetting base plate 121, an upsetting insert die 122, and a first ejection mechanism 123. The lower upsetting base plate 121 is disposed opposite to the upper upsetting insert assembly 11. The upsetting insert die 122 is disposed on the upper surface of the lower upsetting base plate 121, and a first through hole is provided in the middle of the upsetting insert die 122. A first through hole is provided on the surface of the lower upsetting base plate 121 opposite to the first through hole. The first ejection mechanism 123 passes through the first through hole and is disposed on the upper surface of the upper upsetting base plate 121. Within a through hole, the top surface of the first ejection mechanism 123 and the wall of the first through hole form a first receiving cavity for accommodating at least a portion of the metal pipe 20. The first ejection mechanism 123 is movably arranged along the axial direction of the first through hole to eject the metal pipe 20 located in the first receiving cavity. The first ejection mechanism 123, the upsetting insert die 122, and the upper upsetting insert assembly 11 form a first receiving space. A first annular clearance groove 124 for processing and forming a first target structure is provided on the side wall of the first through hole.

[0044] The lower upsetting base plate 121 is positioned opposite to the upper upsetting insert assembly 11, providing a stable support foundation for the entire lower upsetting insert assembly 12. The first receiving cavity is used to precisely receive the end of the metal tube 20 to be formed, ensuring that the metal tube 20 is axially positioned stably and without deviation during the upsetting process. At the same time, the first ejection mechanism 123 is axially movable along the first through hole, and can eject the metal tube 20 upward after forming, realizing automatic demolding and effectively avoiding jamming or damage caused by excessive friction in traditional structures. The first annular relief groove 124 provided on the side wall of the first through hole provides forming space for the metal tube 20 to bulge radially under the upsetting pressure, guiding the material to flow in a directional direction and accurately forming the first target structure. This structure works in conjunction with the first receiving cavity to stably constrain the metal tube 20 in the early stage of pressure, controllably expand the material in the middle stage of forming, and smoothly eject it in the later stage of forming, realizing an efficient process flow integrating material gathering and demolding.

[0045] Specifically, the upsetting insert die 122 includes an upsetting die body 1220. The middle part of the upsetting die body 1220 is provided with a first through hole. The first through hole includes a large diameter section 1221 and a small diameter section 1222. The large diameter section 1221 is provided on the side facing the upper upsetting insert assembly 11. The first annular relief groove 124 is provided at the transition connection between the large diameter section 1221 and the small diameter section 1222. During the processing of the metal pipe 20, part of the metal pipe 20 is located in the small diameter section 1222, and part of the end of the upper upsetting insert assembly 11 extends into the large diameter section 1221 to cooperate with the first annular relief groove 124 to process and form the metal pipe 20.

[0046] The first through hole is used to accommodate the metal pipe 20 to be processed. The inner diameter of the large diameter section 1221 is larger than that of the small diameter section 1222, forming a radially expanded accommodating space. The small diameter section 1222 is used to locally constrain the pipe wall of the metal pipe 20, so that when it is subjected to axial pressure, the material can only flow radially outward and cannot become unstable inward. During processing, part of the metal tube 20 is constrained within the small-diameter section 1222, while the end of the upper upsetting insert assembly 11 extends into the large-diameter section 1221 and cooperates with the first annular clearance groove 124. This allows the first annular clearance groove 124 to provide buffering and guiding space when the material flows from the small-diameter section 1222 to the large-diameter section 1221 under axial pressure, making the material flow resistance transition smoothly. This effectively alleviates the stress concentration and uneven material flow caused by abrupt changes in the contact surface, thereby achieving uniform and controllable wall thickness reduction in the preforming stage. This lays a foundation for uniform blank distribution in the subsequent soft mold bulging process, significantly improving the wall thickness consistency and structural integrity of the final molded part.

[0047] It should be noted that the transition connection is the step surface between the large diameter section 1221 and the small diameter section 1222, which forms a radially changing geometric boundary. This location becomes a key control interface for material flow during processing.

[0048] Further, the preformed structure 13 includes a second annular clearance groove 113, and the upper upsetting insert assembly 11 includes an upper upsetting base plate 111, an upper die insert 112, and a first punch 114. The upper upsetting base plate 111 and the lower upsetting base plate 121 are disposed opposite to each other, and the upsetting insert die 122 is located between the upper upsetting base plate 111 and the lower upsetting base plate 121. The first end of the upper die insert 112 is connected to the upper upsetting base plate 111, and the second end of the upper die insert 112 extends toward one side of the upsetting insert die 122. The second end of the upper die insert 112 is provided with a second annular clearance groove 113. The first end of the first punch 114 is connected to the upper upsetting base plate 111. The second end of 4 extends toward one side of the upsetting insert die 122, and the insert 112 on the die is arranged along the circumference of the first punch 114. The first punch 114 can drive the insert 112 on the die to be in the second working position and the second clearance position. When the first punch 114 is in the second working position, part of the insert 112 on the die extends into the large diameter section 1221, and part of the first punch 114 extends into the metal pipe 20. The second annular clearance groove 113 cooperates with the first annular clearance groove 124 to process the metal pipe 20 so that part of the metal pipe 20 is deformed into the first annular clearance groove 124 and the second annular clearance groove 113 until the first target structure.

[0049] In this embodiment, the upper upsetting base plate 111 and the lower upsetting base plate 121 are arranged opposite to each other, forming the upper and lower frames of the upsetting die 10. The first end of the first punch 114 is connected to the upper upsetting base plate 111, and the second end extends axially and is circumferentially wrapped by the insert 112 on the die, so that the first punch 114 can synchronously drive the insert 112 on the die to switch between the second working position and the second clearance position when it moves. When the first punch 114 is in the second working position, part of its structure penetrates into the inner wall of the metal tube 20. At the same time, the second end of the insert 112 on the die extends into the large diameter section 1221 of the upsetting insert die 122. At this time, the second annular clearance groove 113 and the first annular clearance groove 124 pre-set on the upsetting insert die 122 are precisely aligned and together enclose to form a closed deformation constraint space. Under the action of axial pressure, the material of the metal tube 20 is directionally squeezed and can only flow radially into the annular gap, thereby realizing uniform material accumulation and precise forming. This effectively avoids local accumulation or instability caused by the lack of structural guidance, ensuring the geometric accuracy and wall thickness consistency of the first target structure. After forming is completed, the first punch 114 drives the insert 112 on the die to retract to the second clearance position, releasing the radial constraint on the metal tube 20 and providing unobstructed processing conditions for the subsequent soft mold bulging process.

[0050] In order to improve the stability of the movement of the upper upsetting base plate 111 and the lower upsetting base plate 121, a guide cylinder 50 is provided on the upper upsetting base plate 111 and a guide post 40 is provided on the lower upsetting base plate 121.

[0051] Specifically, a limiting step 1140 is provided on the surface of the first punch 114. The height of the limiting step 1140 in the axial direction of the first punch 114 is greater than the height of the lower end of the insert 112 on the die in the axial direction of the first punch 114. The inner sidewall of the insert 112 on the die, a portion of the surface of the first punch 114, and the limiting step 1140 form a gap for the sidewall of the metal tube 20 to pass through.

[0052] The gap formed by the outer surface of the first punch 114 and the limiting step 1140 allows the sidewall of the metal tube 20 to pass along a preset path during axial compression. This effectively constrains the radial displacement and lateral offset of the metal tube 20 during the upsetting and extrusion stage, preventing uneven deformation caused by local stress concentration or material instability. This ensures that the material of the metal tube 20 is uniformly gathered along the target area under the action of the preforming structure 13, improving the material gathering accuracy and wall thickness distribution consistency. This lays a reliable geometric and material foundation for the subsequent soft mold bulging die 30 to accurately bulge and form the second target structure from the first target structure.

[0053] Furthermore, the upper upsetting insert assembly 11 includes a first fixing plate 125 and a first elastic member 126. The first fixing plate 125 is disposed outside the first punch 114, and a first limiting cavity 1251 is formed between the first fixing plate 125, the first punch 114, and the upper upsetting base plate 111. One end of the die insert 112 is movably disposed in the first limiting cavity 1251. The first elastic member 126 is disposed in the first limiting cavity 1251, and the first elastic member 126 is located between the top of the die insert 112 and the first fixing plate 125.

[0054] In this embodiment, one end of the die insert 112 is movably inserted into the first limiting cavity 1251, allowing the die insert 112 to slide along the cavity wall of the first limiting cavity 1251 during its downward movement, thus avoiding rigid collisions. When the first punch 114 drives the die insert 112 downward to complete the material accumulation, the die insert 112 is compressed by the first elastic element 126. When the material accumulation is completed and the first punch 114 returns, the first elastic element 126 releases its elastic potential energy, pushing the die insert 112 to automatically reset to its initial position along the first limiting cavity 1251. This effectively eliminates the rigid impact between the die insert 112 and the lower upsetting insert assembly, preventing insert misalignment and mold damage. At the same time, it ensures the stability of the demolding process and the repeatability of the equipment positioning accuracy, providing a precise workpiece reference for the subsequent soft mold forming process.

[0055] Furthermore, the lower soft mold insert assembly 32 includes a lower soft mold base plate 321, a soft mold cavity 322, and a second ejection mechanism 323. The soft mold cavity 322 has a large diameter section 3221 and a small diameter section 3222. The lower soft mold base plate 321 is disposed opposite to the upper soft mold insert assembly 31; the soft mold cavity 322 is connected to the lower soft mold base plate 321, the lower soft mold base plate 321 is provided with a second through hole, and a second through hole is provided on the surface of the lower soft mold base plate 321 opposite to the second through hole; the second ejection mechanism 323 is disposed in the second through hole through the second through hole, and the top surface of the second ejection mechanism 323 and the hole wall of the second through hole form a first receiving cavity for accommodating at least part of the metal tube 20, and the second ejection mechanism 323 is movably disposed along the axial direction of the second through hole to eject the metal tube 20 located in the first receiving cavity; wherein, the second ejection mechanism 323, the soft mold cavity 322 and the upper upsetting insert assembly 11 form a second receiving space, and a third annular clearance groove 324 for processing and forming a second target structure is provided on the side wall of the second through hole.

[0056] In this embodiment, the second ejection mechanism 323 can move axially along the second through hole to achieve stable ejection of the formed metal tube 20. After the metal tube 20 expands into the second target structure within the second receiving space through the soft mold structure, the upper soft mold insert assembly 31 moves to the avoidance position, and the second ejection mechanism 323 moves upward. By applying a lifting force through the bottom of the first receiving cavity, the metal tube 20 is disengaged from the soft mold cavity 322. The third annular avoidance groove 324 provided on the side wall of the second through hole precisely matches the outer contour of the second target structure, providing an interference-free avoidance space for the bulging protrusion, ensuring that the complex contour does not get stuck or scratched during the ejection process, achieving automated and highly reliable demolding. This solves the technical problem that traditional soft mold bulging molds are difficult to eject stably due to the complex outer contour of the metal tube 20, and improves the yield and production efficiency of the formed parts.

[0057] Furthermore, the second ejection mechanism 323 includes a top plate 3231, the top plate 3231 has a relief recess in the middle, and an annular gap is formed between the outer peripheral surface of the top plate 3231 and the hole wall of the second through hole for the lower end side wall of the metal pipe 20 to pass through.

[0058] In this embodiment, the avoidance recess ensures that when the top plate 3231 pushes the metal tube 20 upward, its core area does not contact the bottom center area of ​​the metal tube 20, thereby avoiding indentation or plastic deformation in the center area due to local stress concentration. At the same time, an annular gap is formed between the outer peripheral surface of the top plate 3231 and the hole wall of the second through hole, so that the outer edge of the bottom of the metal tube 20 only receives uniform support and ejection force through this annular area. The force range is precisely limited to the outer peripheral part with stable tube wall thickness, avoiding direct compression and friction of thin-walled areas by traditional solid ejection structures, and significantly reducing the risk of scratches.

[0059] Furthermore, the upper soft mold insert assembly 31 includes an upper soft mold base plate 311, a second punch 312, a second fixing plate 313, an upper soft mold insert 314, a second elastic element 316, and an expanding soft mold 317. The upper soft mold base plate 311 is disposed opposite to the lower soft mold base plate 321. The first end of the second punch 312 is connected to the upper soft mold base plate 311, and the second end of the second punch 312 extends toward the lower soft mold base plate 321. The second fixing plate 313 is connected to the upper soft mold base plate 311 and is located outside the second punch 312, and a second limiting is formed between the second fixing plate 313 and the upper soft mold base plate 311. Space; one end of the upper soft mold insert 314 is movably disposed in the second limiting space, and the other end of the upper soft mold insert 314 is provided with a fourth annular clearance groove 315 for processing and forming the second target structure; the second elastic element 316 is disposed in the second limiting space and is located between the end of the upper soft mold insert 314 and the upper soft mold base plate 311; the bulging soft mold 317 is connected to the upper soft mold base plate 311 through the connecting rod 318, the bulging soft mold 317 is located at the end of the second punch 312, the bulging soft mold 317 is movably disposed relative to the connecting rod 318, and the connecting rod 318 is disposed inside the second punch 312.

[0060] In this embodiment, the upper soft mold base plate 311 and the lower soft mold base plate 321 are arranged opposite to each other, providing a stable alignment foundation for the entire soft mold bulging structure. The second punch 312 directly drives the bulging soft mold 317 to apply radial bulging force to the inner wall of the metal pipe; the second limiting space is used to constrain the movement trajectory of the upper soft mold insert 314. The fourth annular relief groove 315 dynamically conforms to the deformation contour of the metal pipe during the bulging process, providing rigid support for the outer edge area of ​​the bulging soft mold 317 and avoiding local overstretching. The second elastic element 316 provides controllable elastic resistance during the bulging process, allowing the upper soft mold insert 314 to slide slowly inward, achieving synchronous coordination with the deformation of the inner wall of the metal pipe. The inner core area of ​​the bulging soft mold 317 has independent flexible deformation capability when it is compressed and expanded. The connecting rod 318 is set inside the second punch 312 to avoid interfering with the direct action path of the punch, realize precise control of material flow in small rounded corners and large deformation areas, significantly improve the forming accuracy and wall thickness uniformity of the second target structure, and effectively solve the problem of thickness loss due to local stress concentration.

[0061] According to another aspect of the present invention, an embodiment of a method and apparatus for forming metal tubes is also provided.

[0062] This method is performed at room temperature and falls under the category of cold plastic forming of metallic materials. The method includes three steps: material preparation, preforming, and forming. Sufficient deformable material is obtained through material preparation. Preforming and forming control the amount and area of ​​deformation, gradually shaping the material to achieve the desired form, thereby controlling thinning and improving the uniformity of wall thickness in the deformed area. Figure 2 As shown.

[0063] The metal pipe fitting 20 is a round pipe or a simple irregularly shaped pipe with a wall thickness of no more than 5 mm. Preferably, the wall thickness of the metal pipe fitting 20 is no less than 1 mm and no more than 4 mm. The material of the metal pipe fitting 20 is steel, aluminum alloy, copper alloy, etc., preferably low carbon steel such as Q235 and 16Mn. The metal pipe fitting 20 can be a welded pipe or a seamless pipe, etc., preferably a seamless pipe.

[0064] The deformation region structure of the metal fitting 20 is a ring-shaped structure that bulges outward radially along the metal fitting 20, such as... Figure 3 As shown, the outer corner of the bulging structure has a small radius, resulting in a large amount of forming deformation.

[0065] The material is aggregated using an upsetting process. Under internal and external constraints, the metal tube 20 yields and compresses in a designated area. The material aggregated during upsetting should be slightly higher than the required volume (weight) of the material in that deformation area, thus providing sufficient material for subsequent bulging. The upsetting compression stroke can be calculated from the volume of the deformation area and the inner and outer diameters of the metal tube 20. For example, if the volume of the deformation area obtained by 3D modeling software or manual calculation is V, and the inner diameter d and outer diameter D of the metal tube 20 are D, then the upsetting compression stroke is H = 4V / π(D²-d²). The outer contour dimensions of the part obtained in the aggregated step are generally slightly larger than those in the preforming step. To avoid interference between the part and the die, the difference in contour dimensions should not exceed 7mm.

[0066] Preforming employs a soft-mold bulging process to obtain a specific trapezoidal profile. This trapezoidal profile initially distributes the material gathered in the previous step into several parts. Compared to the target structure, the trapezoidal profile has larger fillets, thus reducing thinning near the fillets and improving the uniformity of the preformed profile. Furthermore, the outer edge of the trapezoidal profile is located outside the target structure, increasing the line length of the preformed profile to provide material for subsequent forming. Generally, the design of the preformed trapezoidal profile should ensure that the profile length is close to or slightly larger than the profile length of the target structure. The outer contour dimension of the part obtained in the preforming step is generally slightly larger than that of the part obtained in the forming step. To avoid interference between the part and the die, the difference in contour dimensions should not exceed 5 mm.

[0067] The forming process also employs a soft mold bulging technique, further distributing material to the rounded corner areas to obtain the required contour dimensions and achieving uniform thickness and minimal thinning in the deformed area. After forming is complete, pressure holding is required to reduce springback, typically for 3-10 seconds.

[0068] To reduce work hardening and improve formability, an annealing process can be added between the three steps.

[0069] The forming device uses an upsetting die 10 for the material gathering step and a soft mold bulging die 30 for the preforming and forming steps.

[0070] The upsetting die 10 has internal and external constraints to prevent the metal tube 20 from becoming unstable inward in the bulging area. An elastic pressure structure is used to close and open the concave die cavity, thereby enabling the upsetting and demolding of the metal tube 20. Figure 4 As shown, the upsetting die 10 includes an upper upsetting base plate 111, a first fixing plate 125, an upper die insert 112, an upsetting insert die 122, a first ejection mechanism 123, a lower upsetting base plate 121, a first elastic element 126, and a first punch 114. In the material gathering step, the upper upsetting base plate 111 drives the first punch 114 and the upper die insert 112 downward under the action of the press. When the downward movement reaches the point where the upper die insert 112 and the upsetting insert die 122 are in contact, the upper die insert 112 stops moving downward, the first elastic element 126 is compressed, and the first punch 114 continues to move downward to press down the tube material, so that it deforms and gathers material in the set area. When the compression of the metal tube 20 reaches the set height, the first punch 114 stops moving downward and returns with the upper upsetting base plate 111. During this process, the upper die insert 112 also moves upward and returns, the die cavity opens, and the ejector plate ejects the part under the action of the press.

[0071] A soft mold forming die uses a punch to compress a soft mold, causing the material to yield and deform, fitting into the inner surface of the die cavity. Figure 5 The diagram shows a soft mold bulging mold 30 for the preforming step. The soft mold bulging mold 30 includes an upper soft mold base plate 311, a second fixing plate 313, an upper soft mold insert 314, a soft mold cavity 322, a top plate 3231, a lower soft mold base plate 321, a second elastic element 316, a second punch 312, a connecting rod 318, and a bulging soft mold 317. In the preforming step, the upper soft mold base plate 311 drives the second punch 312 and the upper soft mold insert 314 downward under the action of the press. When the upper soft mold insert 314 and the soft mold cavity 322 are in contact, the upper soft mold insert 314 stops moving downward, the second elastic element 316 is compressed, and the second punch 312 continues to move downward and press down on the expanding soft mold 317, so that the axial height of the expanding soft mold 317 decreases and the radial dimension increases, and the metal tube 20 is squeezed to deform it. When the metal tube 20 is in contact with the contour of the preformed cavity, the punch stops moving downward and holds pressure for 3s-10s. Then the second punch 312 returns with the upper soft mold base plate 311. During this process, the upper soft mold insert 314 also moves upward and returns. The cavity opens, and the ejector plate ejects the part under the action of the press.

[0072] The soft mold forming step and the soft mold forming step have basically the same structure. The difference lies in the contour of the die. The preforming step has a trapezoidal structure, while the forming step has the target structure.

[0073] The bulging soft mold is a polyurethane block with a required hardness of Shore D 90 degrees or higher.

[0074] The method and apparatus of the present invention can effectively reduce the thickness reduction of the metal pipe 20 during bulging, improve the thickness uniformity of the deformation area, and improve the strength and performance of the metal pipe 20.

[0075] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0076] (1) Significantly improve the uniformity of wall thickness and structural strength of the deformation area: Under the synergistic effect of the upsetting die 10 and the soft die forming die 30, especially with the setting of the preformed structure 13, the uniformity of wall thickness is effectively improved by applying directional plastic deformation to a specific area of ​​the metal pipe 20.

[0077] (2) Small rounded corners with little thinning: The first annular relief groove 124 and the second annular relief groove 113 are fitted together, so that the material flows into the closed groove cavity in a directional manner, avoiding stretching and thinning.

[0078] (3) No internal pressure and low energy consumption: The soft die is directly pressed down by the first punch 114, and the pressure is uniformly transmitted to the inner wall of the pipe through the expansion soft die 317. The stamping can be completed without complex accessories such as sealing rings, air pumps, and pressure sensors.

[0079] (4) High consistency mass production: The first punch 114 drives the insert 112 on the die to move precisely back and forth between the second working position and the second avoidance position without manual adjustment, thus achieving high consistency mass production.

[0080] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0081] In addition to the above, it should be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this specification refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this invention.

[0082] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An apparatus for forming metal pipe fittings, characterized in that, include: An upsetting die (10) includes an upper upsetting insert assembly (11) and a lower upsetting insert assembly (12). A first receiving space for accommodating a metal pipe fitting (20) to be processed is formed between the upper upsetting insert assembly (11) and the lower upsetting insert assembly (12). A pre-forming structure (13) is provided on both the upper upsetting insert assembly (11) and the lower upsetting insert assembly (12). The pre-forming structure (13) is used to extrude the metal pipe fitting (20) so that a portion of the sidewall of the metal pipe fitting (20) protrudes outward toward the radial direction of the metal pipe fitting (20) to form a first target structure. A soft mold forming mold (30) includes an upper soft mold insert assembly (31) and a lower soft mold insert assembly (32). A second receiving space for accommodating a metal pipe fitting (20) to be processed is formed between the upper soft mold insert assembly (31) and the lower soft mold insert assembly (32). The upper soft mold insert assembly (31) is provided with a soft mold structure (310). The upper soft mold insert assembly (31) has a first processing position that moves toward the lower soft mold insert assembly (32) to process the metal tube (20) forming the first target structure, and the upper soft mold insert assembly (31) has a first clearance position away from the lower soft mold insert assembly (32). When the upper soft mold insert assembly (31) is in the first processing position, at least a portion of the soft mold structure (310) is filled in the metal tube (20), and the first target structure is bulged until the second target structure is formed.

2. The equipment for forming metal pipe fittings according to claim 1, characterized in that, The upper upsetting insert assembly (11) has a second processing position that moves toward the lower upsetting insert assembly (12) to process the metal tube (20), and the upper upsetting insert assembly (11) has a second avoidance position away from the lower upsetting insert assembly (12).

3. The equipment for forming metal pipe fittings according to claim 1 or 2, characterized in that, The preformed structure (13) includes a first annular clearance groove (124), and the lower upsetting insert assembly (12) includes: The lower upsetting base plate (121) is disposed opposite to the upper upsetting insert assembly (11); Upsetting insert die (122), the upsetting insert die (122) is disposed on the upper surface of the lower upsetting base plate (121), the middle part of the upsetting insert die (122) is provided with a first through hole, and the lower upsetting base plate (121) is provided with a first through hole on the surface opposite to the first through hole; The first ejection mechanism (123) is inserted into the first through hole through the first through hole. The top surface of the first ejection mechanism (123) and the hole wall of the first through hole form a first receiving cavity for accommodating at least part of the metal pipe (20). The first ejection mechanism (123) is movably arranged along the axial direction of the first through hole to eject the metal pipe (20) located in the first receiving cavity. The first ejection mechanism (123), the upsetting insert die (122), and the upper upsetting insert assembly (11) are arranged to form the first receiving space, and the first annular clearance groove (124) for processing and forming the first target structure is provided on the side wall of the first through hole.

4. The equipment for forming metal pipe fittings according to claim 3, characterized in that, The upsetting insert die (122) includes: An upsetting die body (1220) is provided with a first through hole in the middle of the upsetting die body (1220). The first through hole includes a large diameter section (1221) and a small diameter section (1222). The large diameter section (1221) is provided on the side facing the upper upsetting insert assembly (11). The first annular clearance groove (124) is provided at the transition connection between the large diameter section (1221) and the small diameter section (1222). During the processing of the metal pipe (20), part of the metal pipe (20) is located in the small diameter section (1222), and part of the end of the upper upsetting insert assembly (11) extends into the large diameter section (1221) to cooperate with the first annular clearance groove (124) to process and form the metal pipe (20).

5. The equipment for forming metal pipe fittings according to claim 4, characterized in that, The preformed structure (13) includes a second annular clearance groove (113), and the upper upsetting insert assembly (11) includes: An upper upsetting base plate (111) is provided opposite to the lower upsetting base plate (121), and the upsetting insert die (122) is located between the upper upsetting base plate (111) and the lower upsetting base plate (121). The upper die insert (112) has a first end connected to the upper upsetting base plate (111), and a second end extending toward one side of the upsetting insert die (122). The second end of the upper die insert (112) is provided with a second annular clearance groove (113). A first punch (114) has its first end connected to the upper upsetting base plate (111). The second end of the first punch (114) extends toward one side of the upsetting insert die (122), and the insert (112) on the die is arranged circumferentially along the first punch (114). The first punch (114) can drive the insert (112) on the die to a second working position and a second clearance position. The first punch (114) is located in the second... In the working position, part of the die insert (112) extends into the large diameter section (1221), part of the first punch (114) extends into the metal tube (20), and the second annular clearance groove (113) cooperates with the first annular clearance groove (124) to process the metal tube (20) so that part of the metal tube (20) is deformed into the first annular clearance groove (124) and the second annular clearance groove (113) until the first target structure.

6. The equipment for forming metal pipe fittings according to claim 5, characterized in that, A limiting step (1140) is provided on the surface of the first punch (114). The height of the limiting step (1140) in the axial direction of the first punch (114) is greater than the height of the lower end of the die insert (112) in the axial direction of the first punch (114). The inner sidewall of the die insert (112) and part of the surface of the first punch (114) and the limiting step (1140) are arranged to form a gap for the sidewall of the metal tube (20) to pass through.

7. The equipment for forming metal pipe fittings according to claim 5, characterized in that, The upper upsetting insert assembly (11) includes: The first fixing plate (125) is disposed outside the first punch (114), and the first fixing plate (125), the first punch (114), and the upper upsetting bottom plate (111) form a first limiting cavity (1251), and one end of the upper die insert (112) is movably disposed in the first limiting cavity (1251); The first elastic element (126) is disposed in the first limiting cavity (1251) and the first elastic element (126) is located between the top of the insert (112) on the die and the first fixing plate (125).

8. The equipment for forming metal pipe fittings according to claim 1, characterized in that, The lower soft mold insert assembly (32) includes: The lower soft mold base plate (321) is disposed opposite to the upper soft mold insert assembly (31); A soft mold cavity (322) is connected to the lower soft mold base plate (321). The lower soft mold base plate (321) has a second through hole. A second through hole is provided on the surface of the lower soft mold base plate (321) opposite to the second through hole. The second ejection mechanism (323) is disposed in the second through hole through the second through hole. The top surface of the second ejection mechanism (323) and the hole wall of the second through hole form a first receiving cavity for accommodating at least part of the metal tube (20). The second ejection mechanism (323) is movably disposed along the axial direction of the second through hole to eject the metal tube (20) located in the first receiving cavity. The second ejection mechanism (323), the soft mold cavity (322), and the upper upsetting insert assembly (11) are arranged to form the second receiving space, and a third annular clearance groove (324) for processing and forming the second target structure is provided on the side wall of the second through hole.

9. The equipment for forming metal pipe fittings according to claim 8, characterized in that, The second ejection mechanism (323) includes: The top plate (3231) has a relief recess in the middle, and an annular gap is formed between the outer peripheral surface of the top plate (3231) and the hole wall of the second through hole for the lower side wall of the metal pipe (20) to pass through.

10. The equipment for forming metal tubes according to claim 9, characterized in that, The upper soft mold insert assembly (31) includes: An upper soft mold base plate (311) is provided opposite to the lower soft mold base plate (321); The second punch (312) has its first end connected to the upper soft mold base plate (311) and its second end extending toward the lower soft mold base plate (321). The second fixing plate (313) is connected to the upper soft mold base plate (311) and located outside the second punch (312), and a second limiting space is formed between the second fixing plate (313) and the upper soft mold base plate (311); The upper soft mold insert (314) has one end movably disposed within the second limiting space, and the other end of the upper soft mold insert (314) is provided with a fourth annular clearance groove (315) for processing and forming the second target structure. The second elastic element (316) is disposed within the second limiting space and located between the end of the upper soft mold insert (314) and the upper soft mold base plate (311); An expanding soft mold (317) is connected to the upper soft mold base plate (311) via a connecting rod (318). The expanding soft mold (317) is located at the end of the second punch (312). The expanding soft mold (317) is movably arranged relative to the connecting rod (318). The connecting rod (318) is located inside the second punch (312).

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