Water swelling forming device and forming method for clamping and pressing pipe

Abstract

The invention discloses a water swelling forming device and method for a compression pipe, and belongs to the technical field of compression pipe forming. The lower forming mechanism of the clamping and pressing pipe water swelling forming device comprises a lower die, and the upper surface of the lower die is provided with a first forming cavity for conducting primary forming on a pipe and a second forming cavity for conducting secondary forming on the pipe subjected to primary forming. A first plunger which is coaxial with the primary forming cavity and a second plunger which is coaxial with the secondary forming cavity are arranged on a mounting seat of the water expansion mechanism, the first plunger is used for carrying out primary forming of expanding on the pipe, and the second plunger is used for carrying out secondary forming of sealing cavity forming on the expanded pipe; medium flow channels arranged in the centers of the first plunger and the second plunger are communicated with an external medium tank. By the adoption of the water swelling forming device and method for the clamping and pressing pipe, the problem that an existing water swelling forming device is poor in forming effect on the different-diameter clamping and pressing pipe can be solved.

Description

Technical Field

[0001] This invention relates to the field of press-fit tube forming technology, and more particularly to a press-fit tube hydroforming device and forming method. Background Technology

[0002] Press-fit tubing, with its advantages of convenient installation and good sealing performance, is widely used in various fields such as building water supply and drainage, gas transmission, and industrial pipeline systems. The forming quality of press-fit tubing has a crucial impact on its performance and service life. Traditional pressing-fit tubing forming methods mainly include cold drawing and hot extrusion. Although cold drawing can ensure the dimensional accuracy of the tubing to a certain extent, it generates significant residual stress inside the tubing during processing. This not only affects the mechanical properties of the tubing but may also lead to problems such as stress corrosion cracking during subsequent use. While hot extrusion can improve the internal structure of the tubing, the difficulty in temperature control during the heating process makes it prone to defects such as oxidation and decarburization on the tubing surface, reducing the tubing's corrosion resistance and aesthetics. Moreover, hot extrusion has low production efficiency and high equipment investment costs, making it difficult to meet the needs of large-scale industrial production.

[0003] Hydraulic expansion forming technology for pipes offers significant advantages. Firstly, it effectively improves the internal structure of the pipe, making its microstructure more uniform and thus enhancing its overall performance, such as pressure resistance and fatigue resistance. Hydraulically expanded pipes maintain good stability under high pressure, reducing the occurrence of accidents such as pipe bursts. Secondly, this technology causes minimal damage to the pipe surface during the forming process, better preserving its smoothness, which helps improve corrosion resistance and extend the pipe's service life. Hydraulic expansion forming technology also boasts high production efficiency, enabling automated production, reducing labor costs, and meeting the needs of large-scale production.

[0004] Existing patent CN202311155619.5 discloses a multi-station, multi-angle compression tube hydroforming machine, comprising: a base shell, a top shell, a control box, a bottom mold mechanism, horizontal plungers, an internal cleaning mechanism, a top mold mechanism, a discharge track, and a pump station; the bottom mold mechanism is disposed within the inner cavity of the base shell; the two internal cleaning mechanisms are respectively disposed at the top of the base shell and located to the right of the two horizontal plungers; wherein, a feeding mechanism is installed on the top left side of the base shell, and a discharge mechanism is disposed on the right side of the top of the base shell. This multi-station, multi-angle compression tube hydroforming machine, by realizing the automatic replacement of the hydroforming mold, can perform complex processing on the tube blank with different shapes and angles, realize different shapes of the compression tube after forming, and realize the cleaning of residual water in the inner cavity of the compression tube at different angles after forming. Although the aforementioned patent can realize multi-station processing of crimped tubes, for unequal diameter crimped tubes, due to the different diameters at both ends of the crimped tube, when the tube is directly formed, the large change in the diameter at both ends during the forming process results in a poor forming effect at the sealing cavity at both ends of the crimped tube, affecting the forming effect of the unequal diameter crimped tube. Summary of the Invention

[0005] The purpose of this invention is to provide a hydraulic expansion forming device and method for press-fit tubes, which solves the problem of poor forming effect of existing hydraulic expansion forming devices on press-fit tubes of different diameters.

[0006] To achieve the above objectives, the present invention provides a hydraulic expansion forming device for press-fit tubes, comprising a lower forming mechanism, an upper forming mechanism, and a hydraulic expansion mechanism. The upper forming mechanism is located directly above the lower forming mechanism, and the hydraulic expansion mechanism is located between the upper and lower forming mechanisms and at both ends of the lower forming mechanism. The lower forming mechanism includes a lower mold, which is mounted on a fixed base. The upper surface of the lower mold is provided with a first forming cavity for primary forming of the tube and a second forming cavity for secondary forming of the tube after primary forming. The mounting base of the hydraulic expansion mechanism is provided with a first plunger coaxial with the primary forming cavity and a second plunger coaxial with the secondary forming cavity. The first plunger is used for primary forming of the tube to expand its diameter, and the second plunger is used for secondary forming of the expanded tube to form a sealing cavity. The media flow channels located at the center of the first and second plungers are both connected to an external media tank.

[0007] Preferably, the fixed base is provided with a positioning structure for positioning the lower mold. The fixed base is fixed on the base, and the base is provided with a water tank located outside the fixed base. The positioning structure includes a first mounting groove located at the center of the upper surface of the fixed base. A positioning block is provided at the bottom of the lower mold. The positioning block is adapted to the first mounting groove and inserted into the first mounting groove. A second mounting groove is provided inside the fixed base. A transmission block is provided inside the second mounting groove. A push rod is provided on the transmission block. A through hole is provided between the first mounting groove and the second mounting groove for the push rod to pass through. A first spring is provided between the transmission block and the bottom of the second mounting groove to apply an upward pushing force to the transmission block. The transmission block is connected to the lower mold through a positioning assembly.

[0008] Preferably, the positioning assembly includes a positioning rod located on both sides of the transmission block. A vertical groove is provided on the fixed base, and the positioning rod is located in the groove and slides along the groove. The groove and the second mounting groove are connected through a mounting hole. A transmission plate is rotatably installed in the mounting hole. A groove is provided on the side wall of the transmission block for inserting a locking head at one end of the transmission plate. A limiting groove is provided on the bottom side wall of the positioning rod for inserting a locking head at the other end of the transmission plate. The transmission block drives the positioning rod to slide up and down along the groove through the transmission plate. A second spring is provided between the bottom end of the positioning rod and the bottom of the groove to apply a downward pulling force to the positioning rod. A positioning groove adapted to the positioning rod is provided on the bottom surface of the lower mold. The top end of the positioning rod is inserted into the positioning groove. A locking structure is provided on the fixed base to lock the positioning rod and the lower mold.

[0009] Preferably, the locking structure includes a fixed sleeve, which is disposed on the upper surface of the fixed base and located on both sides of the first mounting groove. The fixed sleeve has a sliding hole inside, and a locking pin is slidably disposed in the sliding hole. The positioning rod has a locking hole adapted to the locking pin. The lower mold side wall has a through hole for inserting the locking pin into the positioning groove. The locking pin passes through the through hole and is inserted into the locking hole. One end of the locking pin is provided with a sliding rod. One end of the fixed sleeve is provided with a through hole for the sliding rod to pass through. The end of the sliding rod extending out of the fixed sleeve is provided with a handle for pulling the sliding rod. One end of the locking pin and the sliding hole is provided with a third spring for inserting the locking pin into the locking hole.

[0010] Preferably, the first forming cavity is provided with a plurality of support structures for supporting the pipe. The support structure includes a support block, the top of which is an arc surface adapted to the surface of the first forming cavity. The lower mold is provided with a third mounting groove communicating with the first forming cavity. The support block is located in the third mounting groove and is slidably connected to the third mounting groove. The third mounting groove is provided with a positioning platform for positioning the support block so that the top surface of the support block is flush with the first forming cavity. A fourth spring is provided between the support block and the third mounting groove to apply an upward pushing force to the support block.

[0011] Preferably, the water-expanding mechanism includes a support base, which is fixed on the base. The support base is provided with a stamping cylinder that drives the mounting seat to move horizontally. The mounting seat is provided with a guide rod that guides and supports the horizontal sliding of the mounting seat. The support base is provided with a guide hole through which the guide rod passes. The guide rod is slidably connected to the support base.

[0012] Preferably, the second plunger is provided with a limiting structure on its exterior to limit the end of the expanded pipe. The limiting structure includes a limiting sleeve, which is connected to the second plunger through a connecting structure. A slot for limiting the end of the pipe is formed between the limiting sleeve and the end of the second plunger. The end of the pipe is inserted into the slot. A plurality of dividing grooves are evenly provided on the limiting sleeve. The dividing grooves divide the free end of the limiting sleeve into a plurality of plates. The free end of the plates is an inclined surface that facilitates pipe deformation. The end of the dividing groove is an arc-shaped structure.

[0013] Preferably, the connection structure includes an insertion hole on the stepped surface of the second plunger, a limiting sleeve with an insertion rod adapted to the insertion hole, the insertion rod being inserted into the insertion hole, a sliding pin corresponding to the insertion rod being slidably disposed on the side wall of the second plunger, a locking hole for inserting the sliding pin on the insertion rod, a sliding sleeve being threadedly connected to the external surface of the second plunger, the inner surface of the sliding sleeve being inclined, a fixing plate being disposed on the sliding pin, a fifth spring being disposed between the fixing plate and the outer surface of the second plunger to apply an outward pushing force to the sliding pin, the sliding pin contacting the inclined surface of the sliding sleeve under the action of the fifth spring, and the sliding sleeve pushing the sliding pin into the locking hole through the inclined surface.

[0014] Preferably, the upper forming mechanism includes a lifting plate, an upper mold is provided on the lifting plate, a support rod is provided on the support base to guide the lifting of the lifting plate, a top plate is provided at the top of the support rod, a lifting hydraulic cylinder is provided on the top plate to drive the lifting plate to lift, and the upper mold is provided with cavities that are adapted to the first forming cavity and the second forming cavity respectively.

[0015] The forming method based on the above-mentioned clamping tube hydroforming device includes the following steps: S1. Place the new pipe on the support block in the first forming cavity, and put the expanded pipe in the first forming cavity into the second forming cavity; start the lifting hydraulic cylinder, the lifting hydraulic cylinder extends and drives the lifting plate to descend, the lifting plate drives the upper mold to descend, the upper mold and the lower mold close, and the upper mold fixes the pipe in the first forming cavity and the second forming cavity of the lower mold. S2. Start the stamping cylinder. The stamping cylinder extends and drives the mounting seat to move towards the lower mold. The ends of the first plunger and the second plunger are inserted into the pipe openings of the first forming cavity and the second forming cavity, respectively. The medium-pressure medium is sent into the pipe through the flow channels in the first plunger and the second plunger by the power pump. The pipe expands under the action of the medium-pressure medium and is initially formed. Under the pressure of the pipe, the fifth spring contracts and the support block slides down along the third mounting groove. The upper surface of the support block is flush with the first forming cavity. S3. The stamping cylinder continues to extend, and the first and second plungers seal the ends of the pipe. The high-pressure medium is sent into the pipe through the flow channel by the power pump. The stamping cylinder drives the first and second plungers to move inward, and the limiting sleeve drives the pipe end to move into the second forming cavity. The high-pressure medium further forms the initially formed pipe or forms the sealing cavity. After pressure holding, the forming of the crimped pipe is completed. S4. The stamping cylinder retracts, and the mounting seat drives the first and second plungers to move out of the tube; the lifting hydraulic cylinder retracts, driving the upper die to move upward and take out the formed tube.

[0016] The advantages and positive effects of the press-fit tube hydro-expansion molding device and molding method described in this invention are: 1. The present invention has a first forming cavity and a second forming cavity on the lower mold, and a first plunger coaxial with the primary forming cavity and a second plunger coaxial with the secondary forming cavity on the mounting base. The pipe is formed in two steps by the first plunger and the second plunger. The first forming cavity expands the diameter of the pipe, and the second forming cavity forms the sealing cavity. Through the two-step operation, the forming effect of the reducing slip pipe is improved.

[0017] 2. The second plunger of the present invention is provided with a limiting structure to limit the end of the expanded pipe. By limiting the end of the pipe through the limiting structure, the pipe deforms from the middle to both ends, which is beneficial for replenishing material in the middle of the pipe groove, improving the uniformity of pipe forming, and improving the forming effect. The limiting sleeve is evenly provided with a number of dividing grooves, which divide the free end of the limiting sleeve into a number of plates. The plates can deform slightly during the pipe forming process, which facilitates the pipe to slide out of the groove and replenish the pipe from the end of the pipe.

[0018] 3. The lower mold and the fixed base of the present invention are connected by a positioning structure and locked by a locking structure, making the installation and use of the lower mold convenient.

[0019] 4. The present invention provides a support structure inside the first forming cavity. The first forming cavity has a different diameter structure and an uneven surface, which makes it impossible for the pipe to be placed horizontally inside the first forming cavity. The support block supports the pipe, improving the stability and levelness of the pipe placement, and facilitating the insertion of the first plunger into the pipe to form the pipe.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of an embodiment of the present invention; Figure 2 This is a front view structural diagram of an embodiment of the present invention; Figure 3 This is a schematic diagram of the cross-sectional structure of an embodiment of the present invention; Figure 4 This is a top view of the lower forming mechanism according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the cross-sectional structure of the lower forming mechanism according to an embodiment of the present invention. Figure 1 ; Figure 6 for Figure 5 Enlarged view of A in the middle; Figure 7 This is a schematic diagram of the cross-sectional structure of the lower forming mechanism according to an embodiment of the present invention. Figure 2 ; Figure 8 for Figure 7 Enlarged view of B in the middle; Figure 9 This is a three-dimensional structural diagram of the second punch according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the cross-sectional structure of the second punch according to an embodiment of the present invention; Figure 11 for Figure 10 Enlarged view of C; Figure 12 This is a schematic diagram of the structure of the pipe after it has been formed in one piece. Figure 13 This is a schematic diagram of the structure of the pipe after secondary forming.

[0022] Figure Labels 1. Lower forming mechanism; 11. Base; 12. Fixed seat; 13. Water tank; 14. Lower mold; 15. First forming cavity; 16. Second forming cavity; 17. First mounting groove; 18. Second mounting groove; 19. Positioning block; 110. Transmission block; 111. Push rod; 112. First spring; 113. Transmission plate; 114. Mounting hole; 115. Second spring; 116. Positioning rod; 117. Limiting groove; 118. Slide groove; 119. Positioning groove; 120. Through hole; 121. Fixed sleeve; 122. Locking pin; 123. Slide rod; 124. Third spring; 125. Slide hole; 126. Locking hole; 127. Third mounting groove; 128. Support block; 129. Positioning platform; 130. Fourth spring; 2. Water-expanding mechanism; 21. Support base; 22. Stamping cylinder; 23. Mounting base; 24. Guide rod; 25. First plunger; 26. Second plunger; 27. Flow channel; 28. Limiting sleeve; 29. ​​Dividing groove; 210. Sliding sleeve; 211. Slot; 212. Insertion hole; 213. Insert rod; 214. Locking hole; 215. Sliding pin; 216. Fixing plate; 217. Fifth spring; 3. Upper forming mechanism; 31. Top plate; 32. Support rod; 33. Lifting plate; 34. Upper mold; 35. Lifting hydraulic cylinder. Detailed Implementation

[0023] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any inconsistency, the meaning as set forth in this specification or derived from the content described herein shall prevail. Furthermore, the terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application. To accurately describe the technical content of this application and to accurately understand the invention, the following explanations or definitions of the terms used in this specification are provided before describing specific embodiments: The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0025] like Figure 1 , Figure 2 As shown. A pressure tube hydroforming device includes a lower forming mechanism 1, an upper forming mechanism 3 and a hydroforming mechanism 2. The upper forming mechanism 3 is located directly above the lower forming mechanism 1, and the hydroforming mechanism 2 is located between the upper forming mechanism 3 and the lower forming mechanism 1, and at both ends of the lower forming mechanism 1.

[0026] like Figure 3, Figure 4 As shown. The lower forming mechanism 1 includes a lower mold 14. The upper surface of the lower mold 14 is provided with a first forming cavity 15 for one-time forming of the pipe and a second forming cavity 16 for secondary forming of the pipe after one-time forming. The first forming cavity 15 is used for expanding the diameter of the pipe, and the second forming cavity 16 forms sealing cavities at both ends of the expanded pipe. Performing two-step operations on the pipe is beneficial to improving the processing effect of the sealing cavities. The lower mold 14 is mounted on a fixed base 12, which is fixed to a base 11. A water tank 13 is provided on the base 11, located outside the fixed base 12. The water tank 13 is used to receive and collect the medium fluid.

[0027] like Figure 5 As shown. A positioning structure for positioning the lower mold 14 is provided on the fixed base 12. The positioning structure includes a first mounting groove 17 located at the center of the upper surface of the fixed base 12, and a positioning block 19 located at the bottom of the lower mold 14. The positioning block 19 is adapted to the first mounting groove 17 and is inserted precisely into the first mounting groove 17. A second mounting groove 18 is provided inside the fixed base 12, and a transmission block 110 is provided inside the second mounting groove 18. A push rod 111 is fixedly mounted on the transmission block 110, and a through hole is provided between the first mounting groove 17 and the second mounting groove 18 for the push rod 111 to pass through. The push rod 111 is slidably connected to the fixed base 12. A first spring 112 is provided between the bottom of the transmission block 110 and the second mounting groove 18 to apply an upward pushing force to the transmission block 110. Under the action of the first spring 112, the push rod 111 is inserted into the first mounting groove 17.

[0028] The transmission block 110 is connected to the lower mold 14 via a positioning assembly. The positioning assembly includes a positioning rod 116, which is located on both sides of the transmission block 110. A vertical groove 118 is provided on the fixed base 12, and the positioning rod 116 is located in the groove 118 and slides along the groove 118. The groove 118 is connected to the second mounting groove 18 via a mounting hole 114, and a transmission plate 113 is rotatably mounted in the mounting hole 114. The middle part of the transmission plate 113 is rotatably connected to the mounting hole 114. A groove is provided on the side wall of the transmission block 110 for inserting a locking head at one end of the transmission plate 113. The locking head can slide and rotate in the groove to meet the rotation requirements of the transmission plate 113. A limiting groove 117 is provided on the bottom side wall of the positioning rod 116 for inserting a locking head at the other end of the transmission plate 113. The locking head can slide and rotate in the limiting groove 117. The width of the groove and the limiting groove 117 is slightly larger than the diameter of the circular chuck, so that the chuck can only slide and rotate horizontally within the groove and the limiting groove 117, and cannot move vertically relative to it. This allows the transmission block 110 to drive the positioning rod 116 to slide up and down along the slide groove 118 via the transmission plate 113. A second spring 115 is provided between the bottom end of the positioning rod 116 and the bottom of the slide groove 118 to apply a downward pulling force to the positioning rod 116. Under the action of the second spring 115, the positioning rod 116 naturally retracts into the slide groove 118. A positioning groove 119 adapted to the positioning rod 116 is provided on the bottom surface of the lower mold 14. The top end of the positioning rod 116 is inserted into the positioning groove 119 to position the lower mold 14.

[0029] like Figure 6 As shown. The fixed base 12 is provided with a locking structure to lock the positioning rod 116 to the lower mold 14. The locking structure includes a fixed sleeve 121, which is fixedly mounted on the upper surface of the fixed base 12 and located on both sides of the first mounting groove 17. A sliding hole 125 is provided inside the fixed sleeve 121, and a locking pin 122 is slidably disposed within the sliding hole 125. The positioning rod 116 is provided with a locking hole 126 that matches the locking pin 122. A through hole 120 is provided on the side wall of the lower mold 14, allowing the locking pin 122 to be inserted into the positioning groove 119. The locking pin 122 passes through the through hole 120 and is inserted into the locking hole 126, thereby locking the fixed base 12 to the lower mold 14. A sliding rod 123 is fixedly mounted on one end of the locking pin 122, and a through hole is provided on one end of the fixed sleeve 121 for the sliding rod 123 to pass through. The sliding rod 123 is slidably connected to the fixed sleeve 121. The end of the slide rod 123 extending out of the fixed sleeve 121 is provided with a handle for easy sliding. A third spring 124 is provided at one end of the locking pin 122 and the sliding hole 125 to allow the locking pin 122 to insert into the locking hole 126. An inclined surface is provided at the upper part of the end of the locking pin 122 that inserts into the positioning groove 119 to facilitate insertion of the locking pin 122 into the positioning groove 119.

[0030] In use, the positioning block 19 of the lower mold 14 is inserted into the first mounting groove 17. The lower mold 14 presses against the push rod 111, which drives the transmission block 110 to move downward, compressing the first spring 112. The transmission block 110 drives the transmission plate 113 to rotate, and the transmission plate 113 drives the positioning rod 116 to move upward, with the top of the positioning rod 116 inserted into the positioning groove 119. The bottom of the lower mold 14 presses against the locking pin 122, causing the locking pin 122 to slide outward, compressing the third spring 124. After the positioning block 19 of the lower mold 14 is fully inserted into the first mounting groove 17, the positioning block 19 is placed on the bottom surface of the first mounting groove 17, with the locking pin 122 facing the through hole 120. Under the action of the third spring 124, the locking pin 122 is inserted through the through hole 120 into the locking hole 126 of the positioning rod 116, locking the lower mold 14 to the fixed seat 12. The installation and operation of the lower mold 14 are convenient.

[0031] When disassembling the lower mold 14, the slide bar 123 is pulled outward by the handle. The slide bar 123 drives the locking pin 122 to be pulled out from the locking hole 126 of the positioning rod 116. Under the action of the first spring 112 and the second spring 115, the lower mold 14 springs upward and can be directly removed from the fixed base 12. The disassembly of the lower mold 14 is very convenient.

[0032] like Figure 7 , Figure 8 As shown. The first forming cavity 15 is provided with several support structures for supporting the pipe. Each support structure includes a support block 128, the top of which is an arc surface adapted to the surface of the first forming cavity 15. The lower mold 14 has a third mounting groove 127 communicating with the first forming cavity 15. The support block 128 is located within the third mounting groove 127 and slidably connected to it. The support block 128 is precisely inserted into the third mounting groove 127. A positioning platform 129 is provided within the third mounting groove 127 to position the support block 128, making its top surface flush with the first forming cavity 15, thus improving the pipe forming effect. A fourth spring 130 is provided between the support block 128 and the third mounting groove 127 to apply an upward pushing force to the support block 128. Because the first forming cavity 15 has a different diameter structure and an uneven surface, the pipe cannot be placed horizontally in the first forming cavity 15. The support block 128 supports the pipe, improving the stability and levelness of the pipe placement, and making it easier for the first plunger 25 to be inserted into the pipe to form the pipe.

[0033] The water-expanding mechanism 2 includes a support base 21, which is fixed to the base 11. A stamping cylinder 22 is mounted on the support base 21 to drive the horizontal movement of the mounting base 23. The mounting base 23 is located between the support base 21 and the lower die 14. A guide rod 24 is fixedly mounted on the mounting base 23, providing guidance and support for its horizontal sliding. A guide hole is provided on the support base 21 through which the guide rod 24 passes, and the guide rod 24 is slidably connected to the support base 21. A first plunger 25, coaxial with the primary forming cavity, and a second plunger 26, coaxial with the secondary forming cavity, are fixedly mounted on the mounting base 23. The first plunger 25 is used for primary forming of the pipe diameter expansion, and the second plunger 26 is used for secondary forming of the expanded pipe cavity. The media flow channels 27 located at the centers of the first plunger 25 and the second plunger 26 are both connected to an external media tank.

[0034] like Figure 9 , Figure 10 As shown. The second plunger 26 has a limiting structure on its exterior to limit the diameter of the expanded pipe end. The limiting structure includes a limiting sleeve 28, which is connected to the second plunger 26 via a connecting structure. A slot 211 is formed between the limiting sleeve 28 and the end of the second plunger 26 to limit the pipe end. The pipe end is inserted into the slot 211, allowing the pipe to first be formed in the second forming cavity 16 to increase its diameter, and then to form the sealing cavity. This causes the pipe to deform from the middle to both ends, facilitating material replenishment in the middle of the groove, improving the uniformity of pipe forming, and enhancing the forming effect. The limiting sleeve 28 has several evenly distributed dividing grooves 29, which divide the free end of the limiting sleeve 28 into several plates. The free end of each plate is an inclined surface that facilitates pipe deformation. The plates can deform slightly during pipe forming, allowing the pipe to slide out of the slot 211 and allowing material replenishment from the end of the pipe. The end of the dividing groove 29 is an arc-shaped structure. The arc-shaped structure can effectively reduce stress concentration between the plates and prevent the plates from developing micro-cracks due to deformation, thus affecting the service life of the plates.

[0035] like Figure 11As shown. The connection structure includes an insertion hole 212 on the stepped surface of the second plunger 26. A rod 213 adapted to the insertion hole 212 is fixedly mounted on the limiting sleeve 28, and the rod 213 is inserted into the insertion hole 212. A sliding pin 215 corresponding to the rod 213 is slidably mounted on the side wall of the second plunger 26. A locking hole 214 for inserting the sliding pin 215 is provided on the rod 213. A sliding sleeve 210 is threadedly connected to the outside of the second plunger 26. The inner surface of the sliding sleeve 210 is inclined. A fixing plate 216 is fixedly mounted on the sliding pin 215. A fifth spring 217 is provided between the fixing plate 216 and the outer surface of the second plunger 26 to apply an outward pushing force to the sliding pin 215. Under the action of the fifth spring 217, the sliding pin 215 contacts the inclined surface of the sliding sleeve 210, and the sliding sleeve 210 pushes the sliding pin 215 into the locking hole 214 through the inclined surface.

[0036] The upper forming mechanism 3 includes a lifting plate 33, on which an upper mold 34 is fixedly mounted. A support rod 32, which guides the lifting of the lifting plate 33, is fixedly mounted on the support base 21. A top plate 31 is fixedly mounted on the top of the support rod 32, and a lifting hydraulic cylinder 35, which drives the lifting plate 33 to rise and fall, is mounted on the top plate 31. The upper mold 34 is provided with cavities that are adapted to the first forming cavity 15 and the second forming cavity 16, respectively. After the upper mold 34 and the lower mold 14 are closed, a complete forming cavity is formed.

[0037] The forming method of the above-mentioned clamping tube hydroforming device includes the following steps: S1. Place the new pipe on the support block 128 in the first forming cavity 15, and place the expanded pipe in the first forming cavity 15 into the second forming cavity 16. Start the lifting hydraulic cylinder 35, the lifting hydraulic cylinder 35 extends and drives the lifting plate 33 to descend, the lifting plate 33 drives the upper mold 34 to descend, the upper mold 34 and the lower mold 14 close, the upper mold 34 fixes the pipe in the first forming cavity 15 and the second forming cavity 16 of the lower mold 14.

[0038] S2. Start the stamping cylinder 22. The stamping cylinder 22 extends, causing the mounting base 23 to move towards the lower mold 14. The ends of the first plunger 25 and the second plunger 26 are inserted into the openings of the first forming cavity 15 and the second forming cavity 16, respectively. The medium-pressure medium is pumped into the pipe through the flow channels 27 in the first plunger 25 and the second plunger 26 by the power pump. The pipe expands under the action of the medium-pressure medium, and preliminary forming is performed. Under the pressure of the pipe, the fifth spring 217 contracts, and the support block 128 slides downward along the third mounting groove 127. The upper surface of the support block 128 is flush with the first forming cavity 15.

[0039] S3. The stamping cylinder 22 continues to extend, and the first plunger 25 and the second plunger 26 seal the ends of the pipe. The high-pressure medium is sent into the pipe through the flow channel 27 by the power pump. The stamping cylinder 22 drives the first plunger 25 and the second plunger 26 to move inward. The limiting sleeve 28 drives the pipe end to move into the second forming cavity 16. The high-pressure medium further forms the initially formed pipe or forms the sealing cavity. After pressure holding, the forming of the crimped pipe is completed.

[0040] S4. The stamping cylinder 22 retracts, and the mounting base 23 drives the first plunger 25 and the second plunger 26 to move out of the tube; the lifting hydraulic cylinder 35 retracts, driving the upper mold 34 to move upward and take out the formed tube.

[0041] The structures of the pipe after one-time molding and the pipe after two-time molding are as follows: Figure 12 , Figure 13 As shown.

[0042] Therefore, the hydraulic expansion forming device and forming method for crimped tubes described in this invention can solve the problem of poor forming effect of existing hydraulic expansion forming devices for crimped tubes of different diameters.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A pressure tube hydroforming device, comprising a lower forming mechanism, an upper forming mechanism, and a hydroforming mechanism, wherein the upper forming mechanism is located directly above the lower forming mechanism, and the hydroforming mechanism is located between the upper forming mechanism and the lower forming mechanism, and at both ends of the lower forming mechanism, characterized in that: The lower forming mechanism includes a lower mold, which is mounted on a fixed base. The upper surface of the lower mold is provided with a first forming cavity for one-time forming of the pipe and a second forming cavity for secondary forming of the pipe after one-time forming. The mounting base of the water expansion mechanism is provided with a first plunger coaxial with the primary forming cavity and a second plunger coaxial with the secondary forming cavity. The first plunger is used for one-time forming of pipe diameter expansion, and the second plunger is used for secondary forming of the expanded pipe cavity. The media flow channels at the center of the first plunger and the second plunger are both connected to an external media tank.

2. The clamping tube hydroforming device according to claim 1, characterized in that: The fixed base is provided with a positioning structure for positioning the lower mold. The fixed base is fixed on the base, and the base is provided with a water tank located outside the fixed base. The positioning structure includes a first mounting groove located at the center of the upper surface of the fixed base. A positioning block is provided at the bottom of the lower mold. The positioning block is adapted to the first mounting groove and inserted into the first mounting groove. A second mounting groove is provided inside the fixed base. A transmission block is provided inside the second mounting groove. A push rod is provided on the transmission block. A through hole is provided between the first mounting groove and the second mounting groove for the push rod to pass through. A first spring is provided between the transmission block and the bottom of the second mounting groove to apply an upward pushing force to the transmission block. The transmission block is connected to the lower mold through a positioning assembly.

3. The clamping tube hydroforming device according to claim 2, characterized in that: The positioning assembly includes a positioning rod located on both sides of the transmission block. A vertical groove is provided on the fixed base, and the positioning rod is located in the groove and slides along the groove. The groove is connected to the second mounting groove through a mounting hole. A transmission plate is rotatably installed in the mounting hole. A groove is provided on the side wall of the transmission block for inserting a locking head at one end of the transmission plate. A limiting groove is provided on the bottom side wall of the positioning rod for inserting a locking head at the other end of the transmission plate. The transmission block drives the positioning rod to slide up and down along the groove through the transmission plate. A second spring is provided between the bottom end of the positioning rod and the bottom of the groove to apply a downward pulling force to the positioning rod. A positioning groove adapted to the positioning rod is provided on the bottom surface of the lower mold. The top end of the positioning rod is inserted into the positioning groove. A locking structure is provided on the fixed base to lock the positioning rod and the lower mold.

4. The clamping tube hydroforming device according to claim 3, characterized in that: The locking structure includes a fixed sleeve, which is disposed on the upper surface of the fixed base and located on both sides of the first mounting groove. The fixed sleeve has a sliding hole inside, and a locking pin is slidably disposed in the sliding hole. The positioning rod has a locking hole that matches the locking pin. The lower mold side wall has a through hole for inserting the locking pin into the positioning groove. The locking pin passes through the through hole and is inserted into the locking hole. One end of the locking pin is provided with a sliding rod. One end of the fixed sleeve is provided with a through hole for the sliding rod to pass through. The end of the sliding rod extending out of the fixed sleeve is provided with a handle for pulling the sliding rod. One end of the locking pin and the sliding hole is provided with a third spring for inserting the locking pin into the locking hole.

5. The clamping tube hydroforming device according to claim 4, characterized in that: The first forming cavity is provided with a plurality of support structures for supporting the tube. The support structure includes a support block. The top of the support block is an arc surface that matches the surface of the first forming cavity. The lower mold is provided with a third mounting groove that communicates with the first forming cavity. The support block is located in the third mounting groove and is slidably connected to the third mounting groove. The third mounting groove is provided with a positioning platform for positioning the support block so that the top surface of the support block is flush with the first forming cavity. A fourth spring is provided between the support block and the third mounting groove to apply an upward pushing force to the support block.

6. The clamping tube hydroforming device according to claim 5, characterized in that: The water-expanding mechanism includes a support base, which is fixed on the base. The support base is equipped with a stamping cylinder that drives the mounting seat to move horizontally. The mounting seat is equipped with a guide rod that guides and supports the horizontal sliding of the mounting seat. The support base is equipped with a guide hole through which the guide rod passes. The guide rod is slidably connected to the support base.

7. The clamping tube hydroforming device according to claim 6, characterized in that: The second plunger is provided with a limiting structure on its exterior to limit the end of the expanded pipe. The limiting structure includes a limiting sleeve, which is connected to the second plunger through a connecting structure. A slot for limiting the end of the pipe is formed between the limiting sleeve and the end of the second plunger. The end of the pipe is inserted into the slot. Several dividing grooves are evenly provided on the limiting sleeve. The dividing grooves divide the free end of the limiting sleeve into several plates. The free end of the plates is an inclined surface that facilitates pipe deformation. The end of the dividing groove is an arc-shaped structure.

8. The clamping tube hydroforming device according to claim 7, characterized in that: The connection structure includes an insertion hole on the stepped surface of the second plunger, a limiting sleeve with an insertion rod adapted to the insertion hole, the insertion rod being inserted into the insertion hole, a sliding pin corresponding to the insertion rod being slidably disposed on the side wall of the second plunger, a locking hole for inserting the sliding pin on the insertion rod, a sliding sleeve being threaded to the outside of the second plunger, the inner surface of the sliding sleeve being inclined, a fixing plate being disposed on the sliding pin, a fifth spring being disposed between the fixing plate and the outer surface of the second plunger to apply an outward pushing force to the sliding pin, the sliding pin contacting the inclined surface of the sliding sleeve under the action of the fifth spring, and the sliding sleeve pushing the sliding pin into the locking hole through the inclined surface.

9. The clamping tube hydroforming device according to claim 8, characterized in that: The upper forming mechanism includes a lifting plate, an upper mold on the lifting plate, a support rod on the support base that guides the lifting of the lifting plate, a top plate at the top of the support rod, a lifting hydraulic cylinder on the top plate that drives the lifting plate to rise and fall, and cavities on the upper mold that are adapted to the first forming cavity and the second forming cavity respectively.

10. A molding method for a hydraulic expansion molding device for a compression tube according to claim 9, characterized in that, Includes the following steps: S1. Place the new pipe on the support block in the first forming cavity, and put the expanded pipe in the first forming cavity into the second forming cavity; start the lifting hydraulic cylinder, the lifting hydraulic cylinder extends and drives the lifting plate to descend, the lifting plate drives the upper mold to descend, the upper mold and the lower mold close, and the upper mold fixes the pipe in the first forming cavity and the second forming cavity of the lower mold. S2. Start the stamping cylinder. The stamping cylinder extends and drives the mounting seat to move towards the lower mold. The ends of the first plunger and the second plunger are inserted into the pipe openings of the first forming cavity and the second forming cavity, respectively. The medium-pressure medium is sent into the pipe through the flow channels in the first plunger and the second plunger by the power pump. The pipe expands under the action of the medium-pressure medium and is initially formed. Under the pressure of the pipe, the fifth spring contracts and the support block slides down along the third mounting groove. The upper surface of the support block is flush with the first forming cavity. S3. The stamping cylinder continues to extend, and the first and second plungers seal the ends of the pipe. The high-pressure medium is sent into the pipe through the flow channel by the power pump. The stamping cylinder drives the first and second plungers to move inward, and the limiting sleeve drives the pipe end to move into the second forming cavity. The high-pressure medium further forms the initially formed pipe or forms the sealing cavity. After pressure holding, the forming of the crimped pipe is completed. S4. The stamping cylinder retracts, and the mounting seat drives the first and second plungers to move out of the tube; the lifting hydraulic cylinder retracts, driving the upper die to move upward and take out the formed tube.

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