Forming device for variable cross-section pipe with unequal wall thickness

Abstract

The utility model belongs to the technical field of pipe fitting forming, and discloses a forming device for a variable cross-section pipe with unequal wall thickness, which comprises an outer sleeve die and a mandrel, the inner aperture of the outer sleeve die is larger than the outer diameter of the mandrel, and the outer diameter of the mandrel is larger than that of the outer sleeve die. The mandrel is inserted into a pipe to be formed and drives the pipe to be formed to penetrate through the outer sleeve die to obtain the variable-section pipe with the unequal wall thickness, the mandrel is provided with a variable-shaft-diameter section, the variable-shaft-diameter section is extruded on the pipe to be formed to form a variable-pipe-diameter section, the variable-shaft-diameter section is provided with a high-pressure gas outlet, and the high-pressure gas outlet faces the inner wall of the variable-pipe-diameter section. And high-pressure gas is sprayed out from the high-pressure gas outlet and forms a material returning acting force on the inner wall of the variable-pipe-diameter section. According to the utility model, a material returning acting force is generated between the variable-section pipe with the unequal wall thickness and the mandrel through high-pressure gas, so that the material returning device can be smoothly separated from the variable-section pipe with the unequal wall thickness, the acting force between the end part of the variable-section pipe with the unequal wall thickness and the material returning ring is reduced, the wrinkling, buckling and deformation of the variable-section pipe with the unequal wall thickness are avoided, and the yield is further improved.

Description

Technical Field

[0001] The utility model relates to the technical field of pipe forming, in particular to a forming device for pipes with unequal wall thickness and variable cross-section. Background Art

[0002] In cycling equipment, with the development of science and technology, the requirements for lightweight are getting higher and higher. There are two main ways to achieve lightweight: using lightweight materials and adopting lightweight structures, namely material lightweighting and structural lightweighting. Material lightweighting mainly refers to the use of alloys of lightweight materials to manufacture components, such as aluminum and magnesium alloys. For components with certain materials, lightweighting is mainly achieved by designing and manufacturing lightweight structures with reasonable geometric shapes, such as hollow pipes.

[0003] At present, there are a large number of hollow variable cross-section components that combine material lightweighting and structural lightweighting. For structures that mainly bear bending and torsion loads, the use of hollow variable cross-section components can not only reduce the weight but also make full use of the material strength. The pipe drawing process is to force the pipe fittings through the gap between the die hole and the mandrel under the action of the pulling force to obtain pipe fittings of corresponding shapes and sizes. The problem is that when the material is withdrawn, the pipe fittings are directly in contact with the withdrawing device, which is easy to cause deformation and damage to thin-walled pipe fittings. Utility Model Content

[0004] The utility model aims to provide a forming device for tubes with unequal wall thickness and variable cross-section, so as to solve the problem that the formed tubes are easily deformed when the materials are withdrawn.

[0005] To achieve this purpose, the utility model adopts the following technical solutions:

[0006] A forming device for tubes with unequal wall thickness and variable cross-sections, comprising an outer die and a mandrel, wherein the inner diameter of the outer die is larger than the outer diameter of the mandrel, the mandrel is inserted into the tube to be formed and drives the tube to be formed through the outer die to obtain the tube with unequal wall thickness and variable cross-sections, the mandrel has a variable shaft diameter section, the variable shaft diameter section is extruded on the tube to be formed to form a variable tube diameter section, the variable shaft diameter section is provided with a high-pressure gas outlet, the high-pressure gas outlet is arranged toward the inner wall of the variable tube diameter section, the high-pressure gas is ejected from the high-pressure gas outlet and forms a material stripping force on the inner wall of the variable tube diameter section.

[0007] Optionally, the core shaft has a first axial diameter section and a second axial diameter section, the axial diameter of the first axial diameter section is larger than the axial diameter of the second axial diameter section, the two ends of the variable axial diameter section transitionally connect the first axial diameter section and the second axial diameter section, the first axial diameter section is provided with a first axial through hole, one end of the first axial through hole is the high-pressure gas outlet, and the other end of the first axial through hole is the high-pressure gas inlet, the high-pressure gas inlet is located on the end face of the first axial diameter section away from the variable axial diameter section and is connected to the high-pressure gas supply end.

[0008] Optionally, the axial diameter of the first axial diameter section is larger than the inner diameter of the tube to be formed. During the extrusion forming process, the second axial diameter section, the variable axial diameter section and the first axial diameter section can sequentially enter the interior of the tube to be formed and form a variable diameter section and a flared tube section at the rear end of the tube to be formed.

[0009] Optionally, the forming device of the unequal wall thickness variable cross-section tube also includes a clamping die, the inner wall of the clamping die is arranged to fit the outer wall of the unequal wall thickness variable cross-section tube, and the clamping die can clamp the unequal wall thickness variable cross-section tube when the material is withdrawn.

[0010] Optionally, a first oil spray port is provided on the core shaft, the first oil spray port is provided on the front end surface of the core shaft, and the first oil spray port is provided with a sprayer to spray lubricating oil toward the inner wall of the tube to be formed.

[0011] Optionally, a second axial through hole is provided on the core shaft, one end of the second axial through hole is the first oil injection port, and the other end of the second axial through hole is an oil inlet, the oil inlet is provided at the rear end of the core shaft and is always outside the unequal wall thickness variable cross-section tube during the extrusion molding process, and the oil inlet is connected to the lubricating oil supply end.

[0012] Optionally, a medium inlet and a medium outlet are provided on the core shaft, and the medium inlet and the medium outlet are connected via a medium circuit, and the medium circuit is provided inside the core shaft, and a high-temperature medium flows through the medium circuit to heat the core shaft.

[0013] Optionally, the medium circuit includes a plurality of third axial through holes arranged around the axis of the core shaft, and the plurality of third axial through holes are connected in sequence end to end. During the extrusion molding process, the medium inlet and the medium outlet are always outside the unequal wall thickness variable cross-section tube.

[0014] Optionally, a heater is provided on the outer shell mold for heating the outer shell mold.

[0015] Optionally, a second oil injection port is provided at one end of the outer mold facing the material withdrawal direction, and the second oil injection port is arranged toward the outer side wall of the tube to be formed.

[0016] Beneficial effects of the utility model:

[0017] The utility model discloses a forming device for tubes of variable cross-section with unequal wall thickness, a high-pressure gas outlet is arranged on the variable diameter section of the core shaft, and when withdrawing the material, the high-pressure gas is sprayed toward the inner wall of the variable diameter section of the tube of variable cross-section with unequal wall thickness, so that a withdrawing force is generated between the tube of variable cross-section with unequal wall thickness and the core shaft, which facilitates the tube of variable cross-section with unequal wall thickness to be smoothly separated after contacting the withdrawing ring, reduces the force between the end of the tube of variable cross-section with unequal wall thickness and the withdrawing ring, avoids wrinkling, buckling and deformation of the tube of variable cross-section with unequal wall thickness, and thus improves the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structural composition of a forming device for tubes with unequal wall thickness and variable cross-sections provided in an embodiment of the utility model;

[0019] Figure 2 This is a schematic diagram of the principle of the forming process of the forming device for the tubes with unequal wall thickness and variable cross-section provided by the embodiment of the utility model;

[0020] Figure 3 This is a structural schematic diagram of a core shaft in a forming device for tubes with unequal wall thickness and variable cross-sections provided by an embodiment of the utility model;

[0021] Figure 4 It is a structural schematic diagram of a tube to be formed involved in a forming device for tubes with unequal wall thickness and variable cross-section provided in an embodiment of the utility model;

[0022] Figure 5 It is a schematic diagram of the segmented structure of the tubes with unequal wall thickness and variable cross-sections involved in the forming device for the tubes with unequal wall thickness and variable cross-sections provided in the embodiment of the utility model;

[0023] Figure 6 It is a structural schematic diagram of an outer sleeve mold involved in a forming device for tubes with unequal wall thickness and variable cross-section provided by an embodiment of the utility model;

[0024] Figure 7 It is a schematic diagram of the segmented structure of the mandrel involved in the forming device for tubes with unequal wall thickness and variable cross-section provided by an embodiment of the utility model;

[0025] Figure 8 It is a structural schematic diagram of a clamping die involved in a forming device for tubes of unequal wall thickness and variable cross-section provided by an embodiment of the utility model;

[0026] Fig. 9 It is a schematic diagram of the position of the first oil injection port on the mandrel involved in the forming device of the tube with unequal wall thickness and variable cross-section provided by the embodiment of the utility model;

[0027] Fig.10 yes Fig. 9 Middle AA section;

[0028] Fig.11 yes Fig. 9 Middle BB cross section;

[0029] Fig.12 It is a structural schematic diagram of a heater on an outer mold and a second oil injection port involved in a molding device for unequal wall thickness and variable cross-section tubes provided in an embodiment of the utility model.

[0030] In the figure:

[0031] 100, tube to be formed; 200, tube with variable cross-section and unequal wall thickness; 201, tube section with variable diameter; 202, expanded tube section; 300, material withdrawal ring;

[0032] 1. Jacket mold; 11. Heater; 12. Second fuel injection port;

[0033] 2. Mandrel; 21. Variable shaft diameter section; 22. First shaft diameter section; 221. First axial through hole; 2211. High-pressure gas outlet; 2212. High-pressure gas inlet; 23. Second shaft diameter section; 24. Second axial through hole; 241. First oil injection port; 242. Oil inlet; 25. Third axial through hole; 251. Medium inlet; 252. Medium outlet;

[0034] 3. Clamp the mold. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0036] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0038] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0039] The present invention provides a forming device for a tube with unequal wall thickness and variable cross section, which is used for extruding a tube with unequal wall thickness and variable cross section 200, such as Figure 1-Figure 4 As shown, the forming device of the variable-section tube with unequal wall thickness includes an outer die 1 and a core shaft 2. The inner diameter of the outer die 1 is larger than the outer diameter of the core shaft 2. The core shaft 2 is inserted into the tube 100 to be formed and drives the tube 100 to be formed to pass through the outer die 1 to obtain the variable-section tube 200 with unequal wall thickness. The core shaft 2 has a variable shaft diameter section 21. The variable shaft diameter section 21 is extruded on the tube 100 to be formed to form a variable tube diameter section 201. The variable shaft diameter section 21 is provided with a high-pressure gas outlet 2211. The high-pressure gas outlet 2211 is arranged toward the inner wall of the variable tube diameter section 201. The high-pressure gas is ejected from the high-pressure gas outlet 2211 and forms a material stripping force on the inner wall of the variable tube diameter section 201.

[0040] The forming device of the variable-section tube with unequal wall thickness of the utility model drives the tube 100 to be formed toward the outer mold 1 through the core shaft 2. Before passing through the gap between the core shaft 2 and the outer mold 1, the tube 100 to be formed obtains a variable tube diameter section 201 under the extrusion action of the core shaft 2 and the outer mold 1. The tube 100 to be formed forms a tube 200 with unequal wall thickness and variable section in the process of continuously passing through the gap between the core shaft 2 and the outer mold 1. Among them, the variable diameter section 21 on the core shaft 2 is extruded on the tube 100 to be formed to form a variable tube diameter section 201, and a high-pressure gas outlet 2211 is set on the variable diameter section 21 of the core shaft 2. When withdrawing the material, high-pressure gas is sprayed toward the inner wall of the variable tube diameter section 201 of the unequal wall thickness variable cross-section tube 200, so that a withdrawing force is generated between the unequal wall thickness variable cross-section tube 200 and the core shaft 2, which facilitates the smooth separation of the unequal wall thickness variable cross-section tube 200 after contacting the withdrawing ring 300, reduces the force between the end of the unequal wall thickness variable cross-section tube 200 and the withdrawing ring 300, avoids wrinkling, buckling and deformation of the unequal wall thickness variable cross-section tube 200, and thus improves the yield rate. It can be understood that in the process of withdrawing the material after extrusion molding, the end face and the transverse face of the unequal wall thickness variable cross-section tube 200 will generate a compressive force. When the compressive force is greater than the yield force of the unequal wall thickness variable cross-section tube 200, the unequal wall thickness variable cross-section tube 200 will wrinkle (bend). The high-pressure gas outlet 2211 provided in this embodiment provides high-pressure gas, which can assist the withdrawal of the unequal wall thickness variable cross-section tube 200 and reduce the end force of the unequal wall thickness variable cross-section tube 200 during withdrawal, which is particularly suitable for thin-walled pipes. It should be noted that the withdrawal ring 300 refers to a stopper provided on a conventional withdrawal device, and the mandrel 2 passes through the stopper and the unequal wall thickness variable cross-section tube 200 and the stopper to stop, so as to realize the withdrawal of the tube between the unequal wall thickness variable cross-section tube 200 and the mandrel 2. Generally, the stopper is annular, also called a withdrawal ring 300.

[0041] Optionally, the core shaft 2 has a first axial diameter section 22 and a second axial diameter section 23, the axial diameter of the first axial diameter section 22 is larger than the axial diameter of the second axial diameter section 23, and the two ends of the variable axial diameter section 21 are transitionally connected to the first axial diameter section 22 and the second axial diameter section 23. The first axial diameter section 22 is provided with a first axial through hole 221, one end of the first axial through hole 221 is a high-pressure gas outlet 2211, and the other end of the first axial through hole 221 is a high-pressure gas inlet 2212. The high-pressure gas inlet 2212 is located on the end face of the first axial diameter section 22 away from the variable axial diameter section 21 and is connected to the high-pressure gas supply end.

[0042] It should be noted that during the extrusion molding process, the high-pressure gas inlet 2212 is always located outside the tube 100 to be molded or the tube 200 with variable cross-section and unequal wall thickness, so as to provide high-pressure gas. Figure 3 As shown, the first shaft diameter section 22 and the variable shaft diameter section 21 are used to preferentially form a variable diameter section 201 and a flared section 202 at the end of the to-be-formed tube 100 during the extrusion molding process. Specifically, Figure 4-Figure 7 As shown, the front end of the tube 100 to be formed has a preset diameter DX0, the tube 100 to be formed has a uniform wall thickness T01, the outer mold 1 has a tapered tube section PTX2 whose inner diameter gradually decreases from DD1 to DD2 and a straight tube section PTX1 whose inner diameter is DD2, combined with Figure 1 and Figure 2 In the extrusion molding process, the left end of the mandrel 2 is first inserted from right to left into the tube 100 to be molded. The mandrel 2 moves toward the outer mold 1 under the drive of a driving mechanism (such as a hydraulic press). When the outer wall of the necking portion contacts the inner wall of PTX2 of the outer mold 1, resistance is generated. The resistance at this time is greater than Figure 3 The forming force of PI3 and PD4 in the mold is formed. After the mandrel 2 continues to move forward, the right end of the tube 100 to be formed forms a variable diameter section 201, namely the PI3 section and the expanded tube section 202 (the PD4 section with an outer diameter D04). When the mandrel 2 pushes the tube 100 to be formed through the PTX1 section with an inner diameter DD2, the tube 100 to be formed forms a variable wall thickness in the gap between the mandrel 2 and the outer mold 1. After the mandrel 2 passes to the specified position, unequal wall thickness is formed, and finally a variable cross-section tube 200 with unequal wall thickness is obtained. In this embodiment, by setting the first axial through hole 221 in the first axial diameter section 22, a material withdrawal force is formed between the variable axial diameter section 21 and the variable tube diameter section 201 through high-pressure gas, and the high-pressure gas directly acts on the inner wall of the variable tube diameter section 201, thereby facilitating the withdrawal of the variable cross-section tube 200 with unequal wall thickness, thereby improving the yield and withdrawal efficiency.

[0043] Optionally, the forming device of the tube with unequal wall thickness and variable cross-section further includes a clamping die 3, the inner wall of the clamping die 3 is arranged to fit the outer wall of the tube with unequal wall thickness and variable cross-section 200, and the clamping die 3 can clamp the tube with unequal wall thickness and variable cross-section 200 when the material is withdrawn.

[0044] like Figure 8 As shown, the clamp 3 has an inner wall structure that matches the outer wall of the unequal wall thickness variable cross-section tube 200 and can completely fit the outer wall of the unequal wall thickness variable cross-section tube 200. During the material withdrawal process, when the core shaft 2 is separated from the unequal wall thickness variable cross-section tube 200, the unequal wall thickness variable cross-section tube 200 is prone to wrinkling and bending. By clamping the unequal wall thickness variable cross-section tube 200 with the clamp 3, the bending and deformation of the unequal wall thickness variable cross-section tube 200 can be effectively avoided.

[0045] Optionally, a first oil injection port 241 is provided on the core shaft 2 , and the first oil injection port 241 is provided on the front end surface of the core shaft 2 . The first oil injection port 241 is provided with a sprayer to spray lubricating oil toward the inner wall of the tube 100 to be formed.

[0046] like Fig. 9As shown, the circle marked on the front end face of the core shaft 2 is the first oil injection port 241. By arranging a sprayer at the first oil injection port 241, the lubricating oil can be evenly sprayed onto the inner wall of the tube 100 to be formed, which is beneficial to reduce the friction between the core shaft 2 and the tube 100 to be formed.

[0047] Optionally, a second axial through hole 24 is provided on the core shaft 2, one end of the second axial through hole 24 is a first oil injection port 241, and the other end of the second axial through hole 24 is an oil inlet 242. The oil inlet 242 is provided at the rear end of the core shaft 2 and is always outside the variable-section tube 200 with unequal wall thickness during the extrusion molding process. The oil inlet 242 is connected to the lubricating oil supply end.

[0048] Combination Figure 9-11 Preferably, a second axial through hole 24 is provided on the mandrel 2 along the axial direction, the front end of the second axial through hole 24 is connected to the front end face of the mandrel 2 and is provided as a first oil injection port 241, and the oil inlet 242 is provided at the rear end of the mandrel 2, and can be provided at the rear end face or at the rear end shaft diameter section, and during the extrusion molding process, it is ensured that the oil inlet 2342 can always provide continuous lubricating oil, Fig.11 In the illustrated embodiment, the oil inlet 242 is a radial hole disposed at the rear end axial diameter section of the core shaft 2 and connected to the first axial through hole 24, which is convenient for installing and connecting the lubricating oil supply end.

[0049] Optionally, a medium inlet 251 and a medium outlet 252 are provided on the core shaft 2 , and the medium inlet 251 and the medium outlet 252 are connected via a medium circuit. The medium circuit is provided inside the core shaft 2 , and a high-temperature medium flows in the medium circuit to heat the core shaft 2 .

[0050] In order to ensure the yield rate and avoid the impact of climate change (especially low temperature in winter) on molding, since low temperature will increase friction, a medium circuit is set to provide high-temperature medium and increase the temperature of the core shaft 2. This can improve the lubricating effect of the lubricating oil and reduce friction, thereby improving the molding efficiency. Especially when the diameter of the tube 100 to be formed is a thin-walled pipe with a diameter of 2 mm, heating the core shaft 2 can greatly improve the molding efficiency.

[0051] Optionally, the medium circuit includes a plurality of third axial through holes 25 arranged around the axis of the core shaft 2, and the plurality of third axial through holes 25 are connected in sequence from head to tail. During the extrusion molding process, the medium inlet 251 and the medium outlet 252 are always outside the variable-section tube 200 with unequal wall thickness.

[0052] like Figure 9-11As shown, a plurality of third axial through holes 25 are arranged at intervals around the axis of the core shaft 2 and form a plurality of channels on the circumference. The head and tail of the plurality of third axial through holes 25 are connected in sequence to form an S-shaped medium circuit. The medium inlet 251 and the medium outlet 252 are both located on the outer peripheral wall of the core shaft 2 at one end facing the material withdrawal direction, and are respectively connected to the ends of two adjacent third axial through holes 25. In this way, a uniform heating effect can be formed in the axial direction of the core shaft 2, the lubricating effect of the lubricating oil is improved, the friction is reduced, and the forming efficiency and yield rate of the variable cross-section tube 200 with unequal wall thickness are improved. Specifically, as Fig.10 and Fig.11 As shown, six third axial through holes 25 are provided on the core shaft 2, one end K1 of the first third axial through hole 25 is a medium inlet 251, and the other end J1 is connected to the J2 end of the second third axial through hole 25 through a through groove, and the end K6 of the sixth third axial through hole 25 is connected to the medium outlet 252. After passing through the medium inlet 251, the high-temperature medium passes through K1, J1, J2, K2, K3, J3, J4, K4, K5, J5, J6, K6 in sequence, and finally flows back from the medium outlet 252. Among them, the oil outlet 241 is arranged between the medium inlet 251 and the medium outlet 252, which is convenient for processing, setting and installation.

[0053] Optionally, a heater 11 is provided on the outer shell mold 1 to heat the outer shell mold 1 .

[0054] During the extrusion and stripping process, Fig.12 The heater 11 is used to heat the outer mold 1, and the core shaft 2 is heated to improve the molding conditions, which is conducive to improving the molding efficiency and the yield rate. Preferably, the heater 11 is wound around the outer side of the outer mold 1 in the form of a resistance wire.

[0055] Optionally, a second oil injection port 12 is provided at one end of the outer mold 1 facing the material withdrawal direction, and the second oil injection port 12 is arranged toward the outer side wall of the tube 100 to be formed.

[0056] like Fig.12 The purpose of providing the second oil injection port 12 at the end of the outer mold 1 is to spray oil toward the outer wall of the tube 100 to be formed during the forming process, thereby reducing the friction between the outer mold 1 and the tube 100 to be formed. The oil injection direction of the second oil injection port 12 is as follows: Fig.12 As shown, uniform oil spraying can be achieved by setting the nozzles, preferably, the nozzles are arranged in an annular manner. The channel on the outer mold 1 connected to the second oil injection port 12 for oil supply is an axial channel arranged on the outer mold 1 or a directly connected pipeline for oil supply.

[0057] According to the forming device of the tube with unequal wall thickness and variable cross-section provided in any of the above embodiments, the forming method of the tube with unequal wall thickness and variable cross-section includes a forming process and a material stripping process, which are specifically as follows:

[0058] Forming process: Figure 1 , fix the outer mold 1, extend the front end of the mandrel 2 into the interior of the tube 100 to be formed, and the mandrel 2 drives the tube 100 to be formed to move toward the outer mold 1 (the direction of movement is as follows Figure 1 As shown by the arrow in the middle, the tube 100 to be formed forms a tube 200 with variable cross-section and unequal wall thickness in the gap between the outer mold 1 and the mandrel 2, as shown in FIG. Figure 2 The variable cross-section tube 200 of unequal wall thickness forms a variable tube diameter section 201 at the variable shaft diameter section 21 of the core shaft 2; Figure 4-Figure 7 As shown, a necking is provided at the front end of the tube 100 to be formed. When the necking moves into the outer mold 1, the outer wall of the necking contacts the inner wall of the tapered tube section PTX2 of the outer mold 1 and forms a resistance. The mandrel 2 moves relatively in the tube 100 to be formed until PTX4 on the mandrel 2 contacts the tube mouth of the tube 100 to be formed and forms a forming force. In this embodiment, the resistance is set to be greater than the forming force, so the PTX4 and PDX4 axial diameter sections on the mandrel 2 are successively inserted into the tube 100 to be formed and form a variable tube. The core shaft 2 relatively moves to the necking portion inside the tube 100 to be formed, and the core shaft 2 pushes the tube 100 to be formed through the tapered tube section TPX2 in the outer mold 1 in sequence. In the gap between the core shaft 2 and the straight tube section TPX1 (length 1.5-5mm), the tube 100 to be formed undergoes wall thickness deformation until the core shaft 2 passes through the specified position. The tube 100 to be formed is formed into a tube 200 with unequal wall thickness and variable cross-section, as shown in FIG. Figure 5 and Figure 7 shown.

[0059] Material withdrawal process: Mandrel 2 moves along the material withdrawal direction, such as Figure 3 and Figure 8 When the mandrel 2 drives the variable cross-section tube 200 with unequal wall thickness until the variable cross-section tube 200 with unequal wall thickness contacts the stripping ring 300, high-pressure gas is ejected from the high-pressure gas outlet 2211 and forms a stripping force on the inner wall of the variable diameter section of the variable cross-section tube 200 with unequal wall thickness, and the variable cross-section tube 200 with unequal wall thickness begins to separate from the mandrel 2. Preferably, a pressure sensor can be provided on the stripping ring 300 to provide a trigger signal. When the variable cross-section tube 200 with unequal wall thickness contacts the stripping ring 300, a trigger signal is generated to the high-pressure gas supply end, and high-pressure gas is started to be provided. The stripping force and the stripping ring 300 are used together to perform stripping, and the stripping efficiency is high and the yield rate is high.

[0060] The above-mentioned forming method of unequal wall thickness variable cross-section tubes sprays high-pressure gas on the inner wall of the variable tube diameter section 201 of the unequal wall thickness variable cross-section tube 200 during the stripping process, so that a stripping force is generated between the unequal wall thickness variable cross-section tube 200 and the core shaft 2, which facilitates the smooth separation of the unequal wall thickness variable cross-section tube 200 when it contacts the stripping ring 300, reduces the direct force between the end of the unequal wall thickness variable cross-section tube 200 and the stripping ring 300, avoids wrinkling, buckling and deformation of the unequal wall thickness variable cross-section tube 200, and thus improves the yield rate.

[0061] Optionally, during the forming and stripping process:

[0062] The heater 11 on the outer mold 1 is started to heat the outer mold 1; the second oil injection port 12 on the outer mold 1 sprays lubricating oil toward the outer wall of the tube 100 to be formed (the oil injection direction is as shown in FIG. Fig.12 Indicated by the arrow in the middle);

[0063] The first oil injection port 241 on the core shaft 2 sprays lubricating oil toward the inner wall of the tube 100 to be formed (the direction of the oil injection is as follows: Fig. 9 Indicated by the arrow in the middle);

[0064] A high-temperature medium passes through the medium circuit on the core shaft 2 to heat the core shaft 2.

[0065] By spraying lubricating oil on the inner and outer walls of the tube 100 to be formed, and heating the core shaft 2 and the outer mold 1, the friction during the extrusion process is reduced, the influence of the ambient temperature on the extrusion process is reduced, and the application range of forming and stripping is improved.

[0066] Optionally, during the material stripping process, the outer sleeve mold 1 is replaced by a clamping mold 3, and the clamping mold 3 clamps the unequal wall thickness variable cross-section tube 200 around the outer wall of the unequal wall thickness variable cross-section tube 200 to prevent the unequal wall thickness variable cross-section tube 200 from bending and deformation during material stripping.

[0067] Optionally, during the forming process, the variable shaft diameter section 21 contacts the variable tube diameter section 201 and forms a forming force, and the tube to be formed 100 contacts the outer sleeve mold 1 and forms a resistance, which is greater than the forming force and preferentially forms the expanded variable tube diameter section 201 and the expanded tube section 202 on the tube to be formed 100.

[0068] By setting the resistance and forming force, multiple sections of variable diameter sections 201 and expanded sections 202 can be formed on the variable cross-section tube 200 with unequal wall thickness, such as Figure 5 The right end of the unequal wall thickness variable cross-section tube 200 shown in the figure has a PI1 segment, a PD1 segment (having an outer diameter D01), a PI3 segment and a PD4 segment (having an outer diameter D04, D04>D01), and the required core shaft 2 is provided with two variable shaft diameter segments 21, as shown in FIG. Figure 7The PIX1 segment, PDX1 segment (shaft diameter DX1), PIX4 segment and PDX4 segment (shaft diameter DX4) shown in FIG require two outer sleeve molds 1. In the variable wall thickness molding process (molding process of PD3 segment, PI2 end and PD2 segment), as shown in FIG. Figure 5 When the wall thickness T1 is less than 0.8 mm, the wall thickness T2 may be greater than 0.1-1.5 times the wall thickness T1, and the wall thickness T01 of the tube 100 to be formed is greater than 1.1-1.5 times the wall thickness T2. The formed wall thickness is controlled by the gap between the axial diameters of the PDX3 segment, the PIX2 segment and the PDX2 segment on the core shaft 2 and the inner walls of the PD3 segment, the PI2 end and the PD2 segment respectively.

[0069] Optionally, during the molding process, multiple outer shell molds 1 are provided along the extrusion molding direction, and the outer shell mold 1 includes a first outer shell mold having a tapered pipe section and a second outer shell mold having a straight pipe section. Multiple first outer shell molds and multiple outer shell molds can be arbitrarily combined according to the molding shape of the variable-section tube 200 with unequal wall thickness.

[0070] like Figure 6 What is shown is a combination of a first outer shell mold and a second outer shell mold. The combination can be an integrated structure setting or a fixed connection setting. The size and shape of the first outer shell mold and the second outer shell mold, as well as the combination method, are combined and set according to the shape of the variable-section tube 200 with unequal wall thickness.

[0071] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the scope of protection of the present invention. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A forming device for tubes with different wall thickness and variable cross-section, characterized in that: The invention comprises an outer die (1) and a mandrel (2); the inner diameter of the outer die (1) is larger than the outer diameter of the mandrel (2); the mandrel (2) is inserted into a tube (100) to be formed and drives the tube (100) to be formed to pass through the outer die (1) to obtain a tube (200) with unequal wall thickness and variable cross-section; the mandrel (2) has a variable shaft diameter section (21); the variable shaft diameter section (21) is extruded on the tube (100) to form a variable tube diameter section (201); the variable shaft diameter section (21) is provided with a high-pressure gas outlet (2211); the high-pressure gas outlet (2211) is arranged toward the inner wall of the variable tube diameter section (201); the high-pressure gas is ejected from the high-pressure gas outlet (2211) and forms a material-removing force on the inner wall of the variable tube diameter section (201).

2. The forming device for unequal wall thickness variable cross-section tubes according to claim 1, characterized in that: The core shaft (2) comprises a first shaft diameter section (22) and a second shaft diameter section (23); the shaft diameter of the first shaft diameter section (22) is larger than the shaft diameter of the second shaft diameter section (23); the two ends of the variable shaft diameter section (21) are transitionally connected to the first shaft diameter section (22) and the second shaft diameter section (23); a first axial through hole (221) is provided on the first shaft diameter section (22); one end of the first axial through hole (221) is the high-pressure gas outlet (2211); the other end of the first axial through hole (221) is the high-pressure gas inlet (2212); the high-pressure gas inlet (2212) is located on the end surface of the first shaft diameter section (22) away from the variable shaft diameter section (21) and is connected to a high-pressure gas supply end.

3. The forming device for unequal wall thickness variable cross-section tubes according to claim 2, characterized in that: The axial diameter of the first axial diameter section (22) is greater than the inner diameter of the tube to be formed (100). During the extrusion molding process, the second axial diameter section (23), the variable axial diameter section (21) and the first axial diameter section (22) can sequentially enter the interior of the tube to be formed (100) and form a variable tube diameter section (201) and a flared tube section (202) at the rear end of the tube to be formed (100).

4. The forming device for unequal wall thickness variable cross-section tubes according to claim 1, characterized in that: It also comprises a clamping die (3), the inner wall of which is arranged to fit the outer wall of the unequal wall thickness variable cross-section tube (200). When the material is withdrawn, the clamping die (3) can clamp the unequal wall thickness variable cross-section tube (200).

5. The forming device for tubes with unequal wall thickness and variable cross-section according to claim 1, characterized in that: The core shaft (2) is provided with a first oil spray port (241), which is arranged on the front end surface of the core shaft (2), and the first oil spray port (241) is provided with a sprayer to spray lubricating oil onto the inner wall of the tube (100) to be formed.

6. The forming device for tubes with unequal wall thickness and variable cross-section according to claim 5, characterized in that: The core shaft (2) is provided with a second axial through hole (24), one end of the second axial through hole (24) is the first oil injection port (241), and the other end of the second axial through hole (24) is an oil inlet (242). The oil inlet (242) is provided at the rear end of the core shaft (2) and is always located outside the unequal wall thickness variable cross-section tube (200) during the extrusion molding process. The oil inlet (242) is connected to a lubricating oil supply end.

7. The forming device for unequal wall thickness variable cross-section tubes according to claim 1, characterized in that: The core shaft (2) is provided with a medium inlet (251) and a medium outlet (252); the medium inlet (251) and the medium outlet (252) are connected via a medium circuit; the medium circuit is arranged inside the core shaft (2); a high-temperature medium flows through the medium circuit to heat the core shaft (2).

8. The forming device for tubes with unequal wall thickness and variable cross-section according to claim 7, characterized in that: The medium circuit comprises a plurality of third axial through holes (25) arranged around the axis of the core shaft (2), and the plurality of third axial through holes (25) are connected in sequence end to end. During the extrusion molding process, the medium inlet (251) and the medium outlet (252) are always located outside the unequal wall thickness variable cross-section tube (200).

9. The forming device for tubes with unequal wall thickness and variable cross-section according to claim 1, characterized in that: The outer shell mold (1) is provided with a heater (11) for heating the outer shell mold (1).

10. The forming device for tubes with unequal wall thickness and variable cross-section according to claim 1, characterized in that: A second oil injection port (12) is provided at one end of the outer mold (1) facing the material withdrawal direction, and the second oil injection port (12) is arranged toward the outer side wall of the tube (100) to be formed.

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