A device and forming method for progressive impact hydraulic forming of multi-way pipes

Abstract

The present invention discloses a device and a forming method for progressive impact hydraulic forming of a multi-way pipe. The device comprises a base and a die arranged on the base, wherein the die is provided with a group of radial punches and a group of axial punches, and the radial punches and the axial punches extend into the die cavity of the die. The device has low cost and good applicability, and can improve the forming limit and forming quality of the pipe, especially the forming quality of the multi-way pipe with rounded corners and small boss features. The method can shorten the forming cycle and improve production efficiency.

Description

Technical Field

[0001] The invention relates to a metal tube hydraulic bulging technology, in particular to a device and a forming method for progressive impact hydraulic forming of a multi-way tube. Background Art

[0002] Multi-way tubes are a type of fluid diversion device, which is widely used in the petrochemical, aerospace, automotive and home appliance industries. The hydraulic bulging technology of multi-way tubes uses liquid as the forming medium, with the help of a press and an internal high-pressure source equipment, to bulge the tube blank in the mold to form a branch tube, and cut off the top of the branch tube to obtain a forming technology for the multi-way tube. The multi-way tubes obtained by the hydraulic bulging process have good surface quality, excellent mechanical properties, and high material utilization. At present, the hydraulic bulging of multi-way tubes must rely on special pressure source equipment to provide high pressure inside the pipe. The existing technology for realizing the hydraulic bulging of multi-way tubes is expensive and costly, and the pressurization and decompression cycle is long, the forming speed is too slow, and the metal tube will rebound after decompression, affecting the forming accuracy. In addition, the hydraulic bulging has poor forming quality when it has small features such as complex cross-sections and rounded corners, which has brought great inconvenience to the promotion and application of the hydraulic bulging technology of multi-way tubes.

[0003] The stamping process has a short forming cycle and high efficiency, and can significantly improve the plastic forming properties of the material. When used in the hydraulic bulging process, it can shorten the process cycle and improve the forming limit, especially in the forming of small features such as fillets and bosses.

[0004] Incremental forming can significantly improve the forming limit and forming quality of materials by gradually forming parts in multiple steps. When applied to the hydraulic bulging process, it can improve the forming limit of pipes. And through multiple cycles of loading, it can improve the springback problem existing in traditional hydraulic bulging and improve the forming quality. Summary of the invention

[0005] The purpose of the present invention is to provide a device and a forming method for progressive impact hydraulic forming of multi-way tubes in view of the shortcomings of the prior art. The device has low cost and good applicability, and can improve the forming limit and forming quality of the tube, especially the forming quality of multi-way tubes with rounded corners and small boss features. The method can shorten the forming cycle and improve production efficiency.

[0006] The technical solution for achieving the purpose of the present invention is:

[0007] A device for progressive impact hydraulic forming of a multi-channel pipe comprises a base, wherein a first bracket and a second bracket are arranged in parallel on the base, a first guide rail and a second guide rail are respectively arranged on the first bracket and the second bracket, a first slide and a second slide symmetrically slidable on the first guide rail and the second guide rail are both arranged on the first guide rail and the second guide rail, a first bearing seat is arranged at one end of the first bracket, a second bearing seat is arranged at the other end of the first bracket, a pair of bearings are arranged inside the first bearing seat and the second bearing seat, the bearing seat is connected to the motor base, a motor is arranged on the motor base, a lead screw passing through the bearing is arranged between the first bearing seat and the second bearing seat, the lead screw is connected to the motor shaft through a coupling, a first radial punch base fixedly connected is respectively arranged on two first slides on the first guide rail and the second guide rail, a second radial punch base fixedly connected is respectively arranged on two second slides on the first guide rail and the second guide rail, a mold is placed in the central area of ​​the physical space surrounded by the first bracket, the second bracket, the first radial punch base and the second radial punch base, the mold comprises an upper half mold and a lower half mold, and the bottom of the lower half mold is fixed on the base;

[0008] The upper mold is cylindrical in shape, the upper part of the cylinder is a cylindrical cavity, a through hole perpendicular to the cylindrical axis is provided on the side wall of the cavity near the bottom, the outward end of the through hole is connected to a connecting hole with an internal thread, a groove with an opening facing inward is provided on the outside of the bottom of the cavity, the opening of the groove is smaller than the diameter of the cavity, a second sealing ring is provided in the groove, the upper mold cavity is provided on the concentric axis of the groove and the cavity, the top of the upper mold cavity is the bottom of the cavity, the diameter of the upper mold cavity is equal to the diameter of the tube blank, a first branch tube forming semicircular mold cavity perpendicular to the upper mold cavity is provided at the bottom position of the upper mold, a first recessed groove is provided on the outer wall at the bottom position of the upper mold, a first flange is provided at the outermost end of the bottom of the upper mold, a group of positioning holes is provided on the bottom of the upper mold, a group of first bolt holes is provided on the first flange, and a first axial punch is provided on the upper part of the upper mold;

[0009] The lower mold is cylindrical in shape, and an inwardly sunken second groove is provided on the outer edge of the outer wall of the upper end of the lower mold. The second groove is used to guide the radial punch when the first groove is molded together. A second branch tube forming semicircular mold cavity is provided on the upper end face of the cylinder. The second branch tube forming semicircular mold cavity and the first branch tube forming semicircular mold cavity are molded together to form a complete branch tube forming mold cavity. A group of positioning columns are provided on the upper end face of the cylinder. The positioning columns are inserted into the positioning holes when the molds are closed. The lower mold cavity is arranged on the axis of the cylinder and is coaxial with the upper mold cavity when the molds are closed. The diameter of the lower mold cavity is equal to the diameter of the tube blank. A second flange is provided on the outer wall of the lower mold, and a group of second bolt holes are provided on the second flange. The position of the second bolt hole corresponds to the first bolt hole and is used for locking the upper and lower molds. A third flange is provided at the bottom of the lower mold, and the third flange is fixed to the base through a group of third bolt holes. A second axial punch is provided at the center of the outer end of the third flange.

[0010] One end of the first radial punch is fixedly connected to the middle part of the first radial punch base, and the other end extends into the branch pipe forming cavity. One end of the second radial punch is fixedly connected to the middle part of the second radial punch base, and the other end extends into the branch pipe forming cavity. The first radial punch base and the second radial punch are symmetrically arranged. The first radial punch and the second radial punch have the same structure and are both standard parts. The head is a cylindrical shaft section with a diameter equal to the outer diameter of the tube blank branch pipe. Behind the cylindrical shaft section is a stepped shaft with a slightly larger diameter for improving the strength of the punch. The tail end is a stepped shaft section with an enlarged diameter for being fixedly connected to the radial punch base.

[0011] The first axial punch comprises a fourth flange, wherein a first cylindrical shaft section perpendicular to the end face of the fourth flange is provided at the center of the fourth flange, wherein the diameter of the first shaft section is equal to the diameter of the cavity, and a step whose diameter is smaller than the diameter of the end face of the first shaft section is provided at the end head of the first shaft section away from the fourth flange, and a first sealing ring is sleeved on the outside of the step, and the outer end of the step is a transition shaft section in a conical shape, and a group of first blind holes perpendicular to the axis line of the transition shaft section are provided on the transition shaft section, and the depth of the first blind holes passes through the axis line of the transition shaft section, and a second shaft section is provided at the outer end of the transition shaft section, and the diameter of the second shaft section is equal to the diameter of the tube blank, and a first stage with a larger inner and smaller outer taper is provided at the outer end of the second shaft section, and a second blind hole is provided at the center of the first stage, and the second blind hole is communicated with the first blind hole to form a liquid through hole, and the fourth flange is also provided with a group of fourth bolt holes connected to the punch of an external press.

[0012] The second axial punch includes a fifth flange, which is provided with a group of fifth bolt holes. The positions of the fifth bolt holes correspond to the third bolt holes. A boss is provided on one side of the fifth flange. A third shaft section perpendicular to the boss is provided at the center of the boss. A second stage with a larger inner and smaller outer taper is provided at the outer end of the third shaft section. The diameter of the third shaft section is equal to the outer diameter of the tube blank, the outer end diameter of the second stage is smaller than the inner diameter of the tube blank, and the inner end diameter of the second stage is larger than the inner diameter of the tube blank.

[0013] The first sealing ring is a hollow cylinder with an inner diameter slightly smaller than the diameter of the middle step of the first axial punch and an outer diameter slightly larger than the diameter of the cavity. It is used to seal the first axial punch and the inner wall of the upper half mold cavity. The second sealing ring is a hollow cylinder with an inner diameter slightly smaller than the outer diameter of the tube blank and an outer diameter slightly larger than the diameter of the upper half mold groove. It is used to seal the outer wall of the upper end of the tube blank and the upper half mold cavity.

[0014] The lead screw is separated from the middle, and the threads on both sides are in opposite directions. The middle of the first slide and the second slide on the first guide rail are provided with internal threads that cooperate with the lead screw, and the bottom is provided with a slide groove that cooperates with the first guide rail. The bottom of the first slide and the second slide on the second guide rail is provided with a slide groove that cooperates with the second guide rail.

[0015] The first sealing ring is installed at the step in the middle of the first axial punch, the second sealing ring is installed in the groove of the upper half mold, the fourth flange at the outer end of the first axial punch is connected to the punch of the press, the first stage is interference fit with the tube blank, the first stage inserted into the tube blank can avoid the internal wrinkles of the tube blank during axial feeding, the connecting hole is connected to the overflow valve, the pressure gauge and the manual hydraulic pump and other components, the first axial punch and the cavity on the upper part of the upper half mold form an annular liquid chamber, the positioning column is inserted into the positioning hole for positioning when the mold is closed, the cylindrical tube blank is placed in the mold cavity formed by the upper mold cavity and the lower mold cavity between the upper and lower molds, and the lower end of the tube blank is interference fit with the second stage of the second axial punch.

[0016] The forming method using the above-mentioned device for progressive impact hydraulic forming of multi-way tubes comprises the following steps:

[0017] 1) Install the mold: Place the base with the radial punch assembly mold on the press platform, wherein the second axial punch is placed in the center of the base, the lower half mold is placed above the second axial punch, the punch section of the second axial punch, i.e. the third axial section and the second stage, are located in the lower mold cavity of the lower half mold, the lower half mold, the second axial punch and the base are fixed to the press platform with a bolt group, the first sealing ring is installed at the step in the middle of the first axial punch, and the fourth flange on the upper end of the first axial punch is connected to the external press punch;

[0018] 2) Place the tube blank: Place the tube blank vertically in the lower die cavity of the lower half die, and preliminarily press down and pre-tighten it to achieve a preliminary seal between the tube blank and the second stage at the upper end of the second axial punch;

[0019] 3) Mold closing and clamping: The second sealing ring is placed in the groove of the upper mold, the upper mold connection hole is connected to the external overflow valve, pressure gauge and manual hydraulic pump assembly, the upper mold is placed above the lower mold, and the first flange and the second flange between the upper and lower molds are fastened with bolts;

[0020] 4) Set process parameters: inject liquid into the cavity of the upper mold to the preset scale, start the motor, drive the first radial punch and the second radial punch to the preset position, set the overflow valve pressure value, and set the press punch downward stroke;

[0021] 5) One-pass impact hydraulic forming: The punch of the press moves downward, driving the first axial punch downward. The first axial punch compresses the liquid in the upper half mold cavity, so that the liquid enters the tube through the first blind hole and the second blind hole of the first axial punch, generating internal high pressure. After reaching the set pressure, the excess liquid flows out through the overflow valve connected to the connecting hole. At the same time, the shoulder between the shaft section and the first stage squeezes the upper end of the tube, pushing the tube downward, and axially replenishing the multi-way tube. The first radial punch and the second radial punch provide back pressure for the top of the tube branch. The punch of the press moves downward to the specified stroke, stops feeding, and completes one-pass impact hydraulic bulging;

[0022] 6) Return fluid replenishment: The first axial punch moves upward under the drive of the press punch, and the first radial punch and the second radial punch retreat to the preset position under the drive of the motor. The external manual hydraulic pump or liquid container replenishes the liquid into the cavity to the preset scale through the connection hole of the upper half mold;

[0023] 7) Multi-pass progressive impact hydraulic forming: Set the downward stroke of the press punch, the press punch is pressed down, driving the first axial punch downward, compressing the volume in the cavity, providing high pressure inside the tube blank, and at the same time pushing the tube blank downward for axial material replenishment. The first radial punch and the second radial punch provide branch pipe back pressure. The first axial punch is pressed down to the preset stroke, and the feeding is stopped to complete the second-pass progressive impact hydraulic bulging. The press punch drives the first axial punch upward, replenishes fluid through the connecting hole, and the first radial punch and the second radial punch retreat according to the preset position. The first axial punch descends to the preset position, and multi-pass progressive impact hydraulic forming is performed under the cyclic loading of the press and the motor;

[0024] 8) After the bulging is completed, the first axial punch rises driven by the punch of the press to pump out the liquid in the cavity, loosen the connecting bolts between the first flange and the second flange of the upper and lower dies, take out the bulged tube blank, cut off the top section of the branch pipe, and obtain the formed multi-way pipe fittings.

[0025] This technical solution integrates the functions of internal high pressure generation and axial feeding of tube blanks, and does not require expensive internal high pressure source equipment. Compared with traditional internal high pressure bulging, impact hydraulic bulging has higher formability of parts, especially in fillet filling and small feature forming. Through step-by-step progressive impact hydraulic loading, it can effectively avoid tube rupture, improve the forming limit of the tube, and form multi-way tube parts with higher branch height and better forming quality.

[0026] This device has low cost and good applicability, and can improve the forming limit and forming quality of the pipe, especially the forming quality of multi-pass pipes with rounded corners and small boss features. This method can shorten the forming cycle and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of an embodiment device;

[0028] Figure 2 It is a schematic longitudinal cross-sectional view of the main part of the mold in the embodiment;

[0029] Figure 3 is a schematic structural diagram of the first axial punch in the embodiment;

[0030] Figure 4 A schematic diagram of a longitudinal section of an upper half mold in an embodiment;

[0031] Figure 5 Schematic diagram of the upper half mold structure in the embodiment;

[0032] Figure 6 This is a schematic diagram of the lower half mold structure in the embodiment;

[0033] Figure 7 Schematic diagram of the structure of the second axial punch in the embodiment.

[0034] In the figure, 1. first axial punch 2. first sealing ring 3. upper half mold 4. second sealing ring 5. lower half mold 6. second axial punch 7. tube blank 8. liquid 9. bolt group 10. first radial punch 11. second radial punch 12. first radial punch base 13. second radial punch base 14 lead screw 15. first bearing seat 16. second bearing seat 17. bearing 18. first guide rail 19. second guide rail 20. first slide 21. second slide 22. motor base 23. coupling 24. motor 25. base 26. first bracket 27. second bracket 1-1. fourth flange 1-2. first shaft section 1-3. step 1-4. transition shaft section 1-5. first blind Hole 1-6. Second shaft section 1-7 First stage 1-8. Second blind hole 1-9 Fourth bolt hole 3-. Cavity 3-. Connecting hole 3-3. Upper mold cavity 3-4. Through hole 3-5. Groove 3-6. First branch tube forming semicircular mold cavity 3-.7 First groove 3-8. First flange 3-9. Positioning hole 3-10. First bolt hole 5-1. Second branch tube forming semicircular mold cavity 5-2. Positioning column 5-3. Lower mold cavity 5-4. Second flange 5-5. Second bolt hole 5-6. Third flange 5-7. Second groove 5-8. Third bolt hole 6-1. Fifth flange 6-2. Boss 6-3. Third shaft section 6-4. Second stage 6-5. Fifth bolt hole. DETAILED DESCRIPTION

[0035] The content of the present invention is further described below in conjunction with the drawings and embodiments, but the present invention is not limited thereto.

[0036] Example:

[0037] Reference Figure 1 , Figure 2A device for progressive impact hydraulic forming of a multi-way pipe includes a base 25, on which two parallel first brackets 26 and second brackets 27 are provided, on which first brackets 26 and second brackets 27 are provided respectively, on which first guide rails 18 and second guide rails 19 are provided respectively, on which first guide rails 18 and second guide rails 19 are provided symmetrical first slides 20 and second slides 21 which can slide on the first guide rails 18 and second guide rails 19, one end of the first bracket 26 is provided with a first bearing seat 15, and the other end is provided with a second bearing seat 16, a pair of bearings 17 are provided inside the first bearing seat 15 and the second bearing seat 16, the bearing seat 16 is connected to a motor base 22, and a motor is provided on the motor base 22 24, a lead screw 14 passing through a bearing 17 is provided between the first bearing seat 15 and the second bearing seat 16, the lead screw 14 is connected to the motor shaft through a coupling 22, a first radial punch base 12 fixedly connected is provided on two first slides 20 respectively on the first guide rail 18 and the second guide rail 19, a second radial punch base 13 fixedly connected is provided on two second slides 21 respectively on the first guide rail 18 and the second guide rail 19, a mold is placed in the central area of ​​the physical space surrounded by the first bracket 26, the second bracket 27, the first radial punch base 12 and the second radial punch base 13, and the mold includes an upper half mold 3 and a lower half mold 5, and the bottom of the lower half mold 5 is fixed on the base 25;

[0038] like Figure 4 , Figure 5 As shown, the upper half mold 3 is cylindrical in shape, the upper part of the cylinder is a cylindrical cavity 3-1, a through hole 3-4 perpendicular to the cylindrical axis is provided on the side wall of the cavity 3-1 near the bottom, the outward end of the through hole 3-4 is connected to a connecting hole 3-2 with an internal thread, a groove 3-5 with an opening facing outward is provided on the bottom of the cavity 3-1, the opening of the groove 3-5 is smaller than the diameter of the cavity 3-1, a second sealing ring 4 is provided in the groove 3-5, the upper mold cavity 3-3 is provided on the concentric axis of the groove 3-5 and the cavity 3-1, and the upper mold The top of the cavity 3-3 is the bottom of the cavity 3-1, the diameter of the upper die cavity 3-3 is equal to the diameter of the tube blank 7, a first branch tube forming semicircular die cavity 3-6 perpendicular to the upper die cavity 3-3 is provided at the bottom position of the upper half die 3, a sunken first groove 3-7 is provided on the outer wall at the bottom position of the upper half die 3, a first flange 3-8 is provided at the outermost end of the bottom of the upper half die, a group of positioning holes 3-9 is provided on the bottom of the upper half die 3, a group of first bolt holes 3-10 is provided on the first flange 3-8, and a first axial punch 1 is provided on the upper part of the upper half die 3;

[0039] The outer shape of the lower half mold 5 is cylindrical, and an inwardly sunken second groove 5-7 is provided on the outer edge of the outer wall of the upper end of the lower half mold 5. The second groove 5-7 is used to guide the radial punch when the first groove 3-7 is molded together. A second branch tube forming semicircular mold cavity 5-1 is provided on the upper end surface of the cylinder. The second branch tube forming semicircular mold cavity 5-1 and the first branch tube forming semicircular mold cavity 3-6 are molded together to form a complete branch tube forming mold cavity. A group of positioning columns 5-2 are provided on the upper end surface of the cylinder. When the mold is closed, the positioning columns 5-2 are inserted into the positioning holes 3-9. The lower mold cavity 5 -3 is arranged on the axis of the cylinder and is coaxial with the upper die cavity 3-3 when the mold is closed. The diameter of the lower die cavity 5-3 is equal to the diameter of the tube blank 7. A second flange 5-4 is arranged on the outer wall of the lower half mold. A group of second bolt holes 5-5 are arranged on the second flange 5-4. The positions of the second bolt holes 5-5 correspond to the first bolt holes 3-10 and are used for locking the upper and lower molds. A third flange 5-6 is arranged at the bottom of the lower half mold. The third flange 5-6 is fixed to the base 25 through a group of third bolt holes 5-8. A second axial punch 6 is arranged at the center of the outer end of the third flange 5-6;

[0040] One end of the first radial punch 10 is fixedly connected to the middle of the first radial punch base 12, and the other end extends into the branch tube forming cavity. One end of the second radial punch 11 is fixedly connected to the middle of the second radial punch base 13, and the other end extends into the branch tube forming cavity. The first radial punch base 12 and the second radial punch 11 are symmetrically arranged. The first radial punch 10 and the second radial punch have the same structure and are both standard parts. The head is a cylindrical shaft section with a diameter equal to the outer diameter of the tube blank branch tube. Behind the cylindrical shaft section is a stepped shaft with a slightly larger diameter for improving the strength of the punch. The tail end is a stepped shaft section with an enlarged diameter for being fixedly connected to the radial punch base.

[0041] like Figure 3 As shown, the first axial punch 1 includes a fourth flange 1-1, a first cylindrical shaft section 1-2 perpendicular to the end face of the fourth flange 1-1 is provided at the center of the fourth flange 1-1, the diameter of the first shaft section 1-2 is equal to the diameter of the cavity 3-1, and the end of the first shaft section 1-2 away from the fourth flange 1-1 is provided with a step 1-3 with a diameter smaller than the end face diameter of the first shaft section 1-2, the outer side of the step 1-3 is covered with a first sealing ring 2, the outer end of the step 1-3 is a transition shaft section 1-4 in a conical shape, and the transition shaft section 1-4 is provided with a group of -4 axis perpendicular to a group of first blind holes 1-5, the depth of the first blind holes 1-5 passes through the axis of the transition shaft section 1-4, the outer end of the transition shaft section 1-4 is provided with a second shaft section 1-6, the diameter of the second shaft section 1-6 is equal to the diameter of the tube blank 7, the outer end of the second shaft section 1-6 is provided with a first stage 1-7 with a larger inner and smaller outer taper, the center of the first stage 1-7 is provided with a second blind hole 1-8, the second blind hole 1-8 is communicated with the first blind hole 1-5 to form a liquid through hole, the fourth flange 1-1 is also provided with a group of fourth bolt holes 1-9 connected to the punch of an external press.

[0042] like Figure 7 As shown, the second axial punch 6 includes a fifth flange 6-1, on which a group of fifth bolt holes 6-5 are provided, and the positions of the fifth bolt holes 6-5 correspond to the third bolt holes 5-8. A boss 6-2 is provided on one side of the fifth flange 6-1, and a third shaft section 6-3 perpendicular to the boss 6-2 is provided at the center of the boss 6-2, and a second stage 6-4 with a larger inner and smaller outer taper is provided at the outer end of the third shaft section 6-3, the diameter of the third shaft section 6-3 is equal to the outer diameter of the tube blank 7, the outer end diameter of the second stage 6-4 is smaller than the inner diameter of the tube blank 7, and the inner end diameter of the second stage 6-4 is larger than the inner diameter of the tube blank 7.

[0043] The first sealing ring 2 is a hollow cylinder with an inner diameter slightly smaller than the diameter of the step 1-3 in the middle of the first axial punch 1 and an outer diameter slightly larger than the diameter of the cavity 3-1. It is used to seal the first axial punch 1 and the inner wall of the upper mold cavity 3-1. The second sealing ring 4 is a hollow cylinder with an inner diameter slightly smaller than the outer diameter of the tube blank 7 and an outer diameter slightly larger than the diameter of the upper mold groove 3-5. It is used to seal the outer wall of the upper end of the tube blank 7 and the upper mold cavity 3-1.

[0044] The lead screw 14 is separated from the middle, and the threads on both sides are in opposite directions. The first slide 20 and the second slide 21 on the first guide rail 18 are provided with internal threads in the middle to cooperate with the lead screw 14, and slide grooves are provided at the bottom to cooperate with the first guide rail 18. The first slide 20 and the second slide 21 on the second guide rail 19 are provided with slide grooves at the bottom to cooperate with the second guide rail 19.

[0045] The first sealing ring 2 is installed at the step 1-3 in the middle of the first axial punch 1, and the second sealing ring 4 is installed in the upper half mold groove 3-5. The fourth flange 1-1 at the outer end of the first axial punch 1 is connected to the press punch. The first stage 1-7 is interference fit with the tube blank 7. The first stage 1-7 inserted into the tube blank 7 can avoid internal wrinkles of the tube blank 7 during axial feeding. The connecting hole 3-2 connects the overflow valve and the pressure gauge assembly. The first axial punch 1 and the cavity 3-1 on the upper part of the upper half mold form an annular liquid 8 cavity. When the mold is closed, the positioning column 5-2 is inserted into the positioning hole 3-9 for positioning. The cylindrical tube blank 7 is placed in the mold cavity formed by the upper mold cavity 3-3 and the lower mold cavity 5-3 in the middle of the upper and lower molds. The lower end of the tube blank 7 is interference fit with the second stage 6-4 of the second axial punch 6.

[0046] The forming method using the above-mentioned device for progressive impact hydraulic forming of multi-way pipes comprises the following steps:

[0047] 1) Install the mold: place the base 25 equipped with the radial punch assembly mold on the press platform, wherein the second axial punch 6 is placed in the center of the base 25, the lower half mold 5 is placed above the second axial punch 6, the punch section of the second axial punch 6, i.e. the third shaft section 6-3 and the second stage section 6-4, are located in the lower mold cavity 5-3 of the lower half mold 5, the lower half mold 5, the second axial punch 6 and the base 25 are fixedly connected to the press platform with a bolt group, the first sealing ring 2 is installed at the step 1-3 in the middle of the first axial punch 1, and the fourth flange 1-1 at the upper end of the first axial punch 1 is connected to the external press punch;

[0048] 2) Placing the tube blank: vertically placing the tube blank 7 in the lower die cavity 5-3 of the lower half die, and preliminarily pressing down and pre-tightening the tube blank 7 to achieve a preliminary seal with the second stage 6-4 at the upper end of the second axial punch 6;

[0049] 3) Mold closing and locking: The second sealing ring 4 is placed in the groove 3-5 of the upper mold, the upper mold connecting hole 3-2 is connected to the external overflow valve, pressure gauge and manual hydraulic pump assembly, the upper mold 3 is placed above the lower mold 5, and the first flange 3-8 and the second flange 5-4 between the upper and lower molds are fastened with the bolt group 9;

[0050] 4) Setting process parameters: injecting liquid 8 into the cavity 3-1 of the upper mold 3 to a preset scale, starting the motor 24, driving the first radial punch 10 and the second radial punch 11 to a preset position, setting the overflow valve pressure value, and setting the press punch downward stroke;

[0051] 5) One-pass impact hydraulic forming: the punch of the press moves downward, driving the first axial punch 1 to move downward. The first axial punch 1 compresses the liquid 8 in the upper half mold cavity 3-1, so that the liquid 8 enters the tube 7 through the first blind hole 1-5 and the second blind hole 1-8 of the first axial punch 1, generating internal high pressure. After reaching the set pressure, the excess liquid 8 flows out through the overflow valve connected to the connecting hole 3-2. At the same time, the shoulder between the shaft section 1-6 and the first stage 1-7 squeezes the upper end of the tube 7, pushing the tube 7 downward, and axially replenishing the multi-way tube. The first radial punch 10 and the second radial punch 11 provide back pressure for the top of the branch tube of the tube 7. The punch of the press moves downward to the specified stroke, stops feeding, and completes one-pass impact hydraulic bulging;

[0052] 6) Return fluid replenishment: The first axial punch 1 moves upward under the drive of the press punch, and the first radial punch 10 and the second radial punch 11 retreat to a preset position under the drive of the motor 24, and an external manual hydraulic pump or liquid container replenishes liquid 8 to a preset scale in the cavity 3-1 through the connecting hole 3-2 of the upper half mold 3;

[0053] 7) Multi-pass progressive impact hydraulic forming: set the downward stroke of the press punch, the press punch is pressed down, driving the first axial punch 1 downward, compressing the volume of the cavity 3-1, providing high pressure inside the tube blank 7, and at the same time pushing the tube blank 7 downward for axial material replenishment, the first radial punch 10 and the second radial punch 11 provide branch pipe back pressure, the first axial punch 1 is pressed down to the preset stroke, the feeding is stopped, and the second progressive impact hydraulic bulging is completed, the press punch drives the first axial punch 1 upward, replenishes fluid through the connecting hole 3-2, the first radial punch 10 and the second radial punch 11 retreat according to the preset position, the first axial punch 1 descends to the preset position, and multi-pass progressive impact hydraulic forming is performed under the cyclic loading of the press and the motor;

[0054] 8) After the bulging is completed, the first axial punch 1 rises driven by the punch of the press to pump out the liquid 8 in the cavity 3-1, loosen the connecting bolts between the first flange 3-8 and the second flange 5-4 of the upper and lower dies, take out the bulged tube blank 7, cut off the top section of the branch pipe, and obtain the formed multi-way pipe fitting.

Claims

1. A device for progressive impact hydraulic forming of multi-way pipes, characterized in that: The invention comprises a base, wherein two first brackets and a second bracket are arranged in parallel on the base, a first guide rail and a second guide rail are respectively arranged on the first bracket and the second bracket, a first slide and a second slide which are symmetrically slidable on the first guide rail and the second guide rail are respectively arranged on the first guide rail and the second guide rail, a first bearing seat is arranged at one end of the first bracket and a second bearing seat is arranged at the other end, a pair of bearings are arranged inside the first bearing seat and the second bearing seat, the bearing seat is connected to the motor base, a motor is arranged on the motor base, a lead screw passing through the bearing is arranged between the first bearing seat and the second bearing seat, the lead screw is connected to the motor shaft through a coupling, a first radial punch base fixedly connected is respectively arranged on the two first slides on the first guide rail and the second guide rail, a second radial punch base fixedly connected is respectively arranged on the two second slides on the first guide rail and the second guide rail, a mold is placed in the central area of ​​the physical space surrounded by the first bracket, the second bracket, the first radial punch base and the second radial punch base, the mold comprises an upper half mold and a lower half mold, and the bottom of the lower half mold is fixed on the base; The upper mold is cylindrical in shape, the upper part of the cylinder is a cylindrical cavity, a through hole perpendicular to the cylindrical axis is provided on the side wall of the cavity near the bottom, the outward end of the through hole is connected to a connecting hole with an internal thread, a groove with an opening facing outward is provided on the outside of the bottom of the cavity, the opening of the groove is smaller than the diameter of the cavity, a second sealing ring is provided in the groove, the upper mold cavity is provided on the concentric axis of the groove and the cavity, the top of the upper mold cavity is the bottom of the cavity, the diameter of the upper mold cavity is equal to the diameter of the tube blank, a first branch tube forming semicircular mold cavity perpendicular to the upper mold cavity is provided at the bottom position of the upper mold, a first recessed groove is provided on the outer wall at the bottom position of the upper mold, a first flange is provided at the outermost end of the bottom of the upper mold, a group of positioning holes is provided on the bottom of the upper mold, a group of first bolt holes is provided on the first flange, and a first axial punch is provided on the upper part of the upper mold; The lower mold is cylindrical in shape, and an outer edge of the outer wall of the upper end of the lower mold is provided with an inwardly sunken second groove. A second branch tube forming semicircular mold cavity is provided on the upper end surface of the cylinder. The second branch tube forming semicircular mold cavity and the first branch tube forming semicircular mold cavity are molded together to form a complete branch tube forming mold cavity. A group of positioning columns are provided on the upper end surface of the cylinder. The positioning columns are inserted into the positioning holes when the molds are closed. The lower mold cavity is arranged on the axis of the cylinder and is coaxial with the upper mold cavity when the molds are closed. The diameter of the lower mold cavity is equal to the diameter of the tube blank. A second flange is provided on the outer wall of the lower mold, and a group of second bolt holes are provided on the second flange. The position of the second bolt hole corresponds to the first bolt hole. A third flange is provided at the bottom of the lower mold, and the third flange is fixed to the base through a group of third bolt holes. A second axial punch perpendicular to the end face of the third flange is provided at the center of the outer end of the third flange. One end of the first radial punch is fixedly connected to the middle of the first radial punch base, and the other end extends into the branch pipe forming mold cavity. One end of the second radial punch is fixedly connected to the middle of the second radial punch base, and the other end extends into the branch pipe forming mold cavity. The first radial punch base and the second radial punch are arranged symmetrically.

2. The device for progressive impact hydroforming of multi-way tubes according to claim 1, characterized in that: The first axial punch comprises a fourth flange, wherein a first cylindrical shaft section perpendicular to the end face of the fourth flange is provided at the center of the fourth flange, wherein the diameter of the first shaft section is equal to the diameter of the cavity, and a step whose diameter is smaller than the diameter of the end face of the first shaft section is provided at the end head of the first shaft section away from the fourth flange, and a first sealing ring is sleeved on the outside of the step, and the outer end of the step is a transition shaft section in a conical shape, and a group of first blind holes perpendicular to the axis line of the transition shaft section are provided on the transition shaft section, and the depth of the first blind holes passes through the axis line of the transition shaft section, and a second shaft section is provided at the outer end of the transition shaft section, and the diameter of the second shaft section is equal to the outer diameter of the tube blank, and a first stage with a larger inner and smaller outer taper is provided at the outer end of the second shaft section, and a second blind hole is provided at the center of the first stage, and the second blind hole is communicated with the first blind hole, and the fourth flange is also provided with a group of fourth bolt holes connected to the punch of an external press.

3. The device for progressive impact hydroforming of multi-way tubes according to claim 1, characterized in that: The second axial punch includes a fifth flange, which is provided with a group of fifth bolt holes. The positions of the fifth bolt holes correspond to the third bolt holes. A boss is provided on one side of the fifth flange. A third shaft section perpendicular to the boss is provided at the center of the boss. A second stage with a larger inner and smaller outer taper is provided at the outer end of the third shaft section. The diameter of the third shaft section is equal to the outer diameter of the tube blank, the outer end diameter of the second stage is smaller than the inner diameter of the tube blank, and the inner end diameter of the second stage is larger than the inner diameter of the tube blank.

4. A forming method using the device for progressive impact hydraulic forming of a multi-way tube according to any one of claims 1 to 3, comprising the following steps: 1) Install the die: Place the base with the radial punch assembly die on the press platform, where: The second axial punch is placed in the center of the base, the lower half mold is placed above the second axial punch, the punch section of the second axial punch, i.e., the third shaft section and the second stage section, are located in the lower die cavity of the lower half mold, the lower half mold, the second axial punch and the base are fixedly connected to the press platform by a bolt group, the first sealing ring is installed at the step in the middle of the first axial punch, and the fourth flange on the upper end of the first axial punch is connected to the punch of the external press; 2) Place the tube blank: Place the tube blank vertically in the lower die cavity of the lower half die, and preliminarily press down and pre-tighten it to achieve a preliminary seal between the tube blank and the second stage at the upper end of the second axial punch; 3) Mold closing and clamping: The second sealing ring is placed in the groove of the upper mold, the connection hole of the upper mold is connected to the external overflow valve, pressure gauge and manual hydraulic pump assembly, the upper mold is placed above the lower mold, and the first flange and the second flange between the upper and lower molds are fastened with bolts; 4) Set process parameters: inject liquid into the cavity of the upper mold to the preset scale, start the motor, drive the first radial punch and the second radial punch to the preset position, set the overflow valve pressure value, and set the press punch downward stroke; 5) One-pass impact hydraulic forming: The punch of the press moves downward, driving the first axial punch downward. The first axial punch compresses the liquid in the cavity of the upper half of the die, so that the liquid enters the tube through the first blind hole and the second blind hole of the first axial punch, generating internal high pressure. After reaching the set pressure, the excess liquid flows out through the overflow valve connected to the connecting hole. At the same time, the shoulder between the shaft section and the first stage squeezes the upper end of the tube, pushing the tube downward, and axially replenishing the multi-way tube. The first radial punch and the second radial punch provide back pressure for the top of the tube branch. The punch of the press moves downward to the specified stroke, stops feeding, and completes one-pass impact hydraulic bulging; 6) Return fluid replenishment: The first axial punch moves upward under the drive of the press punch, and the first radial punch and the second radial punch retreat to the preset position under the drive of the motor. The external manual hydraulic pump or liquid container replenishes the liquid into the cavity to the preset scale through the connection hole of the upper half mold; 7) Multi-pass progressive impact hydraulic forming: Set the downward stroke of the press punch, the press punch is pressed down, driving the first axial punch downward, compressing the volume in the cavity, providing high pressure inside the tube blank, and at the same time pushing the tube blank downward for axial material replenishment. The first radial punch and the second radial punch provide branch pipe back pressure. The first axial punch is pressed down to the preset stroke, and the feeding is stopped to complete the second-pass progressive impact hydraulic bulging. The press punch drives the first axial punch upward, replenishes fluid through the connecting hole, and the first radial punch and the second radial punch retreat according to the preset position. The first axial punch descends to the preset position, and multi-pass progressive impact hydraulic forming is performed under the cyclic loading of the press and the motor; 8) After the bulging is completed, the first axial punch rises driven by the punch of the press to pump out the liquid in the cavity, loosen the connecting bolts between the first flange and the second flange of the upper and lower dies, take out the bulged tube blank, cut off the top section of the branch pipe, and obtain the formed multi-way pipe fittings.

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