Exhaust pipe internal high pressure forming method and forming die

Abstract

The present invention provides an exhaust pipe internal high pressure forming method and a forming die, belonging to the technical field of metal forming. The forming method comprises the steps of making a die, extrusion deformation, internal high pressure forming and laser cutting. The die is first used to perform preliminary extrusion deformation on a blank tube, and then high pressure gas is filled into the blank tube. The blank tube is extruded and formed once by the cooperation of the high pressure gas and the die, and there is no need to bend the tube, thereby avoiding various problems caused by bending the tube. In combination with laser cutting, the exhaust pipe will not be deformed during the cutting process, and there is no need to shape the tube, thereby further simplifying the process steps. The method has the advantages of simple process steps, high production efficiency and good production quality.

Description

Technical Field

[0001] The invention belongs to the technical field of metal forming, and in particular relates to a high pressure forming method for an exhaust pipe, and also relates to a forming die matching the forming method. Background Art

[0002] The automobile exhaust pipe is an important part of the vehicle's exhaust system. It is mainly responsible for guiding the exhaust gas generated by engine combustion to the rear of the vehicle and discharging it into the atmosphere. It is usually composed of multiple components, including exhaust manifold, catalytic converter, intermediate pipe and tail pipe.

[0003] In the existing manufacturing process, the middle pipe and the tail pipe are made by bending, cutting, shaping and punching. The process steps are relatively complicated and the pipe wall at the outer bend is easily thinned due to stretching during the bending process. In addition, the current bending equipment is not accurate enough, which easily causes the problem of poor bending angle. Summary of the invention

[0004] Based on the above problems in the prior art, the present invention provides an exhaust pipe high pressure forming method, which comprises the following steps:

[0005] Step S1: making a mold: making an extrusion mold according to the shape of the exhaust pipe;

[0006] Step S2: extrusion deformation: placing the blank tube into a mold and performing preliminary deformation through extrusion of the mold;

[0007] Step S3: internal high pressure forming: filling the preliminarily deformed blank tube with high pressure gas, and extruding it through the cooperation of gas pressure and mold;

[0008] Step S4: laser cutting: using laser to cut the formed exhaust pipe according to the designed length requirements to produce a finished product.

[0009] The extrusion moving direction of the extrusion die made in step S1 is the same as the bending direction of the exhaust pipe, which is a vertical direction.

[0010] The present invention also provides an exhaust pipe internal high-pressure forming mold that matches the above method, which includes an upper mold, a lower mold, a sealing punch and an inflation punch. The upper mold and the lower mold are relatively slidably connected and the sliding direction is close to or away from each other. The upper mold and the lower mold contact and cooperate with each other to form a forming groove. The sealing punch is located at one end of the forming groove and seals one end of the blank tube in the forming groove. The inflation punch is located at the other end of the forming groove and seals the other end of the blank tube in the forming groove. A forming air channel connecting the inner cavity of the blank tube and an external high-pressure air source is provided in the inflation punch.

[0011] The lower die is provided with a plurality of guide grooves, in which linear bearings are fixedly installed, and the upper die is provided with an optical axis that matches and slides with the linear bearings. The upper die is slidably installed to the lower die through the cooperation of the optical axis and the linear bearings.

[0012] Wherein, the optical axis includes a fixed part and a sliding part, the diameter of the fixed part is larger than that of the sliding part, the upper mold is provided with a mounting hole matching the diameter of the sliding part, the upper mold is fixedly installed with an upper pad on the side away from the lower mold, and the sliding part of the optical axis passes through the mounting hole and is fixed to the fixed part of the optical axis by the cooperation of the upper pad and the upper mold, and the sliding part of the optical axis is slidably matched with the linear bearing; the lower mold is fixedly installed with a lower pad on the side away from the upper mold, and a positioning block is fixedly installed on the lower pad, and a positioning groove matching the positioning block is provided on the contacting side of the lower mold and the lower pad.

[0013] Among them, the blocking punch and the inflation punch both include a mounting seat, on which a pin seat for inserting into the exhaust pipe is installed through a threaded connection; the forming air duct extends from one side of the mounting seat of the inflation punch to the end of the pin seat of the inflation punch, and a sealing gasket surrounding the forming air duct is provided at the connection between the mounting seat of the inflation punch and the pin seat.

[0014] Among them, a locking structure for fixing the relative position of the upper mold and the lower mold is provided on the side of the mold, and the locking structure is a manual locking structure or an automatic locking structure. The manual locking structure is a connecting plate spanning the upper mold and the lower mold, and the two ends of the connecting plate are respectively connected to the upper mold and the lower mold by bolts.

[0015] The lock box of claim 1, wherein the lock plate is provided with a pin hole, the lock box comprising a box body, a box cover and a lock pin, the lock pin is slidably installed in the lock box, one end of the lock pin is a pin head matching the pin hole, and the other end of the lock pin is a lock piston matching the inner cavity of the lock box, the box cover is fixedly covered and installed on the box body, a first return spring is installed on the side of the lock piston close to the box cover, and the first return spring abuts on the box cover, and the box body is provided with a connecting hole connected to the locking airway on the side of the lock piston away from the box cover; the lower mold is provided with a lock groove and a locking airway, one end of the locking airway is connected to the lock groove, and the other end of the locking airway is connected to an external air source, the lock box is fixedly installed in the lock groove, and the external air source is used to provide pressure to drive the lock pin to extend through the locking piston.

[0016] Among them, an air distribution pipe is also fixedly installed at one end of the lower mold, and an air inlet, a locking air outlet and a forming air outlet are provided on the air distribution pipe. The air inlet is connected to an external air source, the locking air outlet is connected to the locking air duct, and the forming air outlet is connected to the forming air duct. An air distribution piston is slidably installed in the air distribution pipe, and a second return spring is installed on the side of the air distribution piston away from the air inlet. The pressure required for the deformation of the second return spring is greater than the pressure required for the deformation of the first return spring. When the second return spring is in a natural state, the air distribution piston blocks the forming air outlet.

[0017] Among them, a stabilizing piston is installed in the air distribution pipe so as to slide between the air distribution piston and the air inlet, the locking air outlet is located between the forming air outlet and the air inlet, a linkage rod is fixedly installed on one side of the stabilizing piston, the linkage rod and the air distribution piston are fixedly connected, and a plurality of air holes connecting the two sides are provided on the stabilizing piston. When the second return spring is in a natural state, the stabilizing piston and the locking air outlet are misaligned, and when air is taken in by the air inlet, the air distribution piston first drives the stabilizing piston to move to block the locking air outlet and then continues to move and then is misaligned with the forming air outlet.

[0018] The present invention has the beneficial effects:

[0019] First, use the mold to perform preliminary extrusion and deformation on the blank tube, and then fill the blank tube with high-pressure gas. The blank tube is extruded and formed in one step by the cooperation of high-pressure gas and the mold. There is no need to bend the tube, which can avoid various problems caused by bending the tube. Combined with laser cutting, the exhaust pipe will not be deformed during the cutting process, and there is no need to reshape the pipe, which further simplifies the process steps and improves production efficiency and quality.

[0020] The forming mold can use a high-pressure gas source as power through the cooperation of the air distribution pipe and the automatic locking structure, and can simultaneously lock the mold and extrude the mold, and can delay the extrusion, that is, lock the mold first, and then perform internal high-pressure forming, thereby improving the forming quality and the stability of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a three-dimensional structural schematic diagram of a high pressure forming die for an exhaust pipe according to the first embodiment.

[0022] Figure 2 It is a schematic diagram of the cross-sectional structure of a high pressure forming die for an exhaust pipe according to the first embodiment.

[0023] Figure 3 It is a schematic diagram of the explosion structure of a high pressure forming die for an exhaust pipe according to the first embodiment.

[0024] Figure 4 It is a schematic diagram of the cross-sectional structure of the inflation punch.

[0025] Figure 5It is a three-dimensional structural schematic diagram of a high pressure forming mold for an exhaust pipe according to the third embodiment.

[0026] Figure 6 It is a schematic diagram of the three-dimensional structure of the upper mold of the third embodiment.

[0027] Figure 7 It is a schematic diagram of the cooperation between the sealing punch driving the blank tube and the lower die.

[0028] Figure 8 It is a schematic diagram of the cross-sectional structure of the lower mold of the third embodiment.

[0029] Fig. 9 It is a schematic diagram of the vertical cross-sectional structure of the lower mold of the third embodiment.

[0030] Fig.10 It is a three-dimensional structural diagram of the lock box.

[0031] Fig.11 It is a schematic diagram of the cross-sectional structure of the lock box.

[0032] Fig.12 This is a schematic diagram of the explosion structure of the lock box.

[0033] Fig.13 It is a schematic diagram of the three-dimensional structure of the gas distribution pipe.

[0034] Fig.14 It is a schematic diagram of the cross-sectional structure of the gas distributor pipe, with a stabilizing piston and a gas distributor piston.

[0035] Fig.15 It is a schematic diagram of the cross-sectional structure of the gas distribution pipe without the stabilizing piston and the gas distribution piston.

[0036] Fig.16 This is a schematic diagram of the coordination between the gas distributor piston, the stabilizing piston, the linkage rod and the second return spring. DETAILED DESCRIPTION

[0037] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Embodiment 1: A manually locked high pressure forming die for an exhaust pipe.

[0039] As attached Figure 1-4The exhaust pipe internal high pressure forming mold shown in the figure comprises an upper mold 1 and a lower mold 2 with rectangular horizontal cross-sections, a sealing punch 3 and an inflation punch 4, the upper surface of the lower mold 2 is provided with a guide groove 5 extending up and down at each of the four vertices of the rectangle, that is, there are four guide grooves 5 in total, and a linear bearing 6 is fixedly installed on the upper end of each guide groove 5, the upper mold 1 is provided with four optical axes 7 that are respectively matched and slidably matched with the four linear bearings 6, the optical axis 7 comprises a fixed portion 8 and a sliding portion 9, the diameter of the fixed portion 8 is larger than the sliding portion 9, and the upper mold 1 is respectively provided with a mounting hole 10 that matches the diameter of the sliding portion 9 at the four vertices of the rectangle, the upper mold 1 is fixedly provided with an upper pad 11 on the side away from the lower mold 2, the sliding portion 9 of the optical axis 7 passes through the mounting hole 10 from top to bottom until the fixed portion 8 is attached to the upper surface of the upper mold 1, and at this time, the sliding portion 9 extends beyond the lower surface of the upper mold 1, and then the optical axis 7 is clamped by the cooperation of the upper pad 11 and the upper mold 1 The optical axis 7 is fixedly installed to the upper mold 1 by the fixing part 8 of the shaft 7, and the sliding part 9 of the optical axis 7 and the linear bearing 6 are inserted into the guide groove 5 in a sliding cooperation, so that the upper mold 1 and the lower mold 2 are relatively slidably connected up and down, and the sliding direction is close to or away from each other; the lower surface of the upper mold 1 is provided with a groove with the same shape as the finished exhaust pipe 42, and the lower surface of the upper mold 1 protrudes downward at the bending part of the finished exhaust pipe 42, and the upper surface of the lower mold 2 is provided with a groove with the same shape as the finished exhaust pipe 42, and the upper surface of the lower mold 2 is concave downward at the bending part of the finished exhaust pipe 42, so that the upper mold 1 and the lower mold 2 contact and cooperate with each other to form a forming groove 12, and the lower mold 2 is fixedly installed with a lower pad 13 on the side away from the upper mold 1, and a positioning block 14 is fixedly installed on the lower pad 13, and a positioning groove matched with the positioning block 14 is provided on the contact side of the lower mold 2 and the lower pad 13. The setting of the positioning block 14 and the positioning groove facilitates the mutual fixed installation of the lower mold 2 and the lower pad 13.

[0040] The plugging punch 3 is located at one end of the forming groove 12 and plugs one end of the blank tube 41 in the forming groove 12, and the inflation punch 4 is located at the other end of the forming groove 12 and plugs the other end of the blank tube 41 in the forming groove 12. A forming airway 15 is provided in the inflation punch 4 to connect the inner cavity of the blank tube 41 and the external high-pressure gas source; the plugging punch 3 and the inflation punch 4 both include a mounting seat 16, and the mounting seat 16 is threadedly connected to install a pin seat 17 for inserting into the exhaust pipe 42; the forming airway 15 extends from one side of the mounting seat 16 of the inflation punch 4 to the end of the pin seat 17 of the inflation punch 4, and a sealing gasket 18 surrounding the forming airway 15 is provided at the connection between the mounting seat 16 of the inflation punch 4 and the pin seat 17. In practical applications, the plugging punch 3 and the inflation punch 4 can adopt the same structure, that is, the forming airway 15 is opened on the basis of the plugging punch 3 to form the inflation punch 4.

[0041] The sides of both sides of the mold are provided with locking structures for fixing the relative positions of the upper mold 1 and the lower mold 2. The locking structure is a manual locking structure. The manual locking structure is a connecting plate 19 that spans the side connection of the upper mold 1 and the lower mold 2. The two ends of the connecting plate 19 are respectively connected to the upper mold 1 and the lower mold 2 by bolts, so as to lock the upper mold 1 and the lower mold 2. The forming mold provided in this embodiment is used in combination with the forming method provided in Example 2.

[0042] Embodiment 2: A high pressure forming method for an exhaust pipe.

[0043] The forming method provided in this embodiment is used in combination with the forming mold provided in the first embodiment. The forming mold provided in the first embodiment is suitable for the forming method provided in this embodiment, which specifically includes the following steps:

[0044] Step S1: making a mold: making an extrusion mold as described in the first embodiment according to the shape of the required exhaust pipe, the exhaust pipe after extrusion is in an up-and-down bending state in the mold, that is, the exhaust pipe is bent in the vertical direction, first bending downward and then bending upward; at the same time, the lower mold 2 of the mold is fixed, the upper mold 1 is located above the lower mold 2 and is connected to the lower mold 2 by sliding up and down, and the upper mold 1 moves downward to extrude the blank tube 41;

[0045] Step S2: extrusion deformation: placing the blank tube 41 on the lower die 2, and driving the upper die 1 to move downward to fit with the lower die 2, extruding the blank tube 41 through the die, and causing the blank tube 41 to be initially deformed;

[0046] Step S3: internal high pressure forming: the relative positions of the upper die 1 and the lower die 2 are locked by a locking structure, and then the plugging punch 3 and the inflation punch 4 are driven to move toward the blank tube 41 and seal the two ends of the blank tube 41, and then the inflation punch 4 is used to fill the preliminarily deformed blank tube 41 with high pressure gas to increase the air pressure in the blank tube 41, and the blank tube 41 is extruded and formed by the cooperation of the air pressure and the mold;

[0047] Step S4: laser cutting: the formed exhaust pipe is taken out of the mold and moved to the laser cutting equipment, and the formed exhaust pipe is cut by laser according to the designed length requirements to form a finished product.

[0048] Embodiment 3: An automatically locked high pressure forming die for an exhaust pipe.

[0049] The difference between this embodiment and the first embodiment is that the installed locking structure is an automatic locking structure. Figure 4-16The exhaust pipe high pressure forming mold shown in the figure comprises two lock plates 20 respectively fixedly mounted on both sides of the lower surface of the upper mold 1, and two lock boxes 22 correspondingly fixedly mounted on both sides of the upper surface of the lower mold 2, each lock plate 20 is provided with a pin hole 21, the lock box 22 comprises a box body 23, a box cover 24 and a lock pin 25, the lock pin 25 is slidably installed in the lock box 22, one end of the lock pin 25 is a pin head 26 matched with the pin hole 21, and the other end of the lock pin 25 is a locking piston 27 matched with the inner cavity of the lock box 22, the box cover 24 is fixedly mounted on the box body 23 by screws, and a first return spring 28 is installed on the side of the locking piston 27 close to the box cover 24, and the first return spring 28 abuts on the box cover 24, and the inner cavity diameter of the box cover 24 is larger than the diameter of the first return spring 28 and smaller than the diameter of the locking piston 27, so that the box cover 24 can limit the locking piston 27 to prevent the locking piston 27 from being locked at high pressure. The first return spring 28 is compressed under pressure, causing damage to the first return spring 28. The box body 23 is provided with a connecting hole 29 connected to the locking air channel 31 on the side of the locking piston 27 away from the box cover 24, and the connecting hole 29 protrudes downward; both sides of the upper surface of the lower mold 2 are provided with locking grooves 30 at the corresponding positions of the locking plate 20, and the lower mold 2 is also provided with a locking air channel 31 connecting the two locking grooves 30. The locking air channel 31 is "T"-shaped, and the two ends of the locking air channel 31 are respectively connected to the two locking grooves 30, and the third end of the locking air channel 31 extends to one end where the inflation punch 4 is provided and is connected to the external air source through the air distribution pipe 32. The lock box 22 is fixedly installed in the locking groove 30 and the connecting hole 29 is inserted into the locking air channel 31. When the locking plates 20 are inserted into the locking grooves 30, the external air source can be used to provide pressure through the locking piston 27 to drive the locking pin 25 to extend and insert into the pin hole 21, thereby locking the upper mold 1 and the lower mold 2.The lower die 2 is also fixedly installed with an air distribution pipe 32 at one end that cooperates with the inflation punch 4. The air distribution pipe 32 is provided with an air inlet 33, a locking air outlet 34 and a forming air outlet 35. The air inlet 33 is connected to an external air source, the locking air outlet 34 is communicated with the locking air channel 31, and the forming air outlet 35 is communicated with the forming air channel 15. An air distribution piston 36 and a stabilizing piston 37 are slidably installed in the air distribution pipe 32. The stabilizing piston 37 is located between the air distribution piston 36 and the air inlet 33, and the locking air outlet 34 is located between the forming air outlet 35 and the air inlet 33. A linkage rod 38 is fixedly installed on one side of the stabilizing piston 37. The moving rod 38 is fixedly connected to the air dividing piston 36, and four air holes 39 communicating with both sides are arranged on the stabilizing piston 37. A second return spring 40 is installed on the side of the air dividing piston 36 away from the air inlet 33. The pressure required for the deformation of the second return spring 40 is greater than the pressure required for the deformation of the first return spring 28. When the second return spring 40 is in a natural state, the air dividing piston 36 blocks the forming air outlet 35, and at the same time, the stabilizing piston 37 and the locking air outlet 34 are misaligned; when air is taken in by the air inlet 33, the air dividing piston 36 first drives the stabilizing piston 37 to move to block the locking air outlet 34, and then continues to move and then is misaligned with the forming air outlet 35.

[0050] The forming mold provided in this embodiment is also used in conjunction with the forming method provided in the second embodiment. The lower mold 2 and the inflating punch 4 are both fixedly arranged, and the air inlet 33 of the air distribution pipe 32 is connected to the external high-pressure air source. When working, the blocking punch 3 can be used as a temporary feeding structure, such as the attached Figure 7 As shown, the blank tube 41 is first inserted into the ejector seat 17 of the plugging punch 3 by using a mechanical arm, manual or other structure, and then the blank tube 41 is driven by the plugging punch 3 to move to the lower die 2 and inserted into the ejector seat 17 of the inflation punch 4 at the same time. At this time, the upper die 1 can be driven to squeeze the blank tube 41 downward to make the blank tube 41 initially deformed, and then the external high-pressure gas source is started to supply gas to the gas distribution pipe 32. When the gas is just inflated, the gas distribution piston 36 blocks the forming gas outlet 35, and the gas can only flow from the locking gas outlet 34 to the lock box 22. The air pressure gradually rises and drives the locking pin 25 to extend. The locking pin 25 extends and is inserted into the pin hole 21 to complete the locking of the upper mold 1 and the lower mold 2. The air pressure continues to rise and drives the gas distributor piston 36 to move. The gas distributor piston 36 drives the stabilizing piston 37 to block the locking air outlet 34, so that the air pressure in the lock box 22 remains stable. Then the gas distributor piston 36 continues to move and opens the forming air outlet 35. The gas begins to flow to the blank tube 41 to increase the air pressure in the blank tube 41. The initially deformed blank tube 41 is completely squeezed into shape through the high air pressure in the tube and the cooperation of the mold.

[0051] After extrusion is completed, the gas is released, and the air pressure in the exhaust pipe 42 and the gas distribution pipe 32 gradually decreases. The second return spring 40 first drives the gas distribution piston 36 to reset, and then drives the blocking punch 3 to leave the exhaust pipe 42 to release the gas in the exhaust pipe 42. At the same time, the gas in the gas distribution pipe 32 continues to decrease, and the first return spring 28 drives the locking pin 25 to reset and release the lock on the upper mold 1 and the lower mold 2. At this time, the mold can be opened and the exhaust pipe 42 can be taken out for laser cutting to make a finished exhaust pipe 42.

[0052] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An exhaust pipe high pressure forming die, characterized in that: The invention comprises an upper die (1), a lower die (2), a plugging punch (3) and an inflation punch (4); the upper die (1) and the lower die (2) are connected in a relative sliding manner and the sliding direction is to move closer to or farther from each other; the upper die (1) and the lower die (2) are in contact with each other to form a forming groove (12); the plugging punch (3) is located at one end of the forming groove (12) and plugs one end of a blank tube (41) in the forming groove (12); the inflation punch (4) is located at the other end of the forming groove (12) and plugs the other end of the blank tube (41) in the forming groove (12); a forming air channel (15) is provided in the inflation punch (4) and is connected to the inner cavity of the blank tube (41) and an external high-pressure air source; and a side surface of the die is provided with a gas passage for fixing the blank tube (41). A locking structure for the relative position of an upper mold (1) and a lower mold (2), wherein the locking structure is an automatic locking structure, and the automatic locking structure comprises a locking plate (20) fixedly mounted on the upper mold (1) and a locking box (22) fixedly mounted on the lower mold (2), wherein the locking plate (20) is provided with a pin hole (21), and the locking box (22) comprises a box body (23), a box cover (24) and a locking pin (25), wherein the locking pin (25) is slidably mounted in the lock box (22), wherein one end of the locking pin (25) is a pin head (26) matching the pin hole (21), and the other end of the locking pin (25) is a locking piston (27) matching the inner cavity of the lock box (22), and the box cover (24) is fixedly mounted on the box body (23) to lock the lock. A first return spring (28) is installed on the side of the piston (27) close to the box cover (24), and the first return spring (28) contacts the box cover (24). The box body (23) is provided with a connecting hole (29) connected to the locking air channel (31) on the side of the locking piston (27) away from the box cover (24); the lower mold (2) is provided with a locking groove (30) and a locking air channel (31), one end of the locking air channel (31) is connected to the locking groove (30), and the other end of the locking air channel (31) is connected to an external air source. The lock box (22) is fixedly installed in the locking groove (30), and the pressure provided by the external air source is used to drive the lock pin (25) to extend through the locking piston (27); one end of the lower mold (2) is also fixedly installed An air distribution pipe (32) is provided on which an air inlet (33), a locking air outlet (34) and a forming air outlet (35) are arranged. The air inlet (33) is connected to an external air source, the locking air outlet (34) is communicated with the locking air channel (31), and the forming air outlet (35) is communicated with the forming air channel (15). An air distribution piston (36) is slidably installed in the air distribution pipe (32), and a second return spring (40) is installed on a side of the air distribution piston (36) away from the air inlet (33). The pressure required for deformation of the second return spring (40) is greater than the pressure required for deformation of the first return spring (28). When the second return spring (40) is in a natural state, the air distribution piston (36) blocks the forming air outlet (35);A stabilizing piston (37) is slidably mounted in the gas distribution pipe (32) between the gas distribution piston (36) and the gas inlet (33); the locking gas outlet (34) is located between the forming gas outlet (35) and the gas inlet (33); a linkage rod (38) is fixedly mounted on one side of the stabilizing piston (37); the linkage rod (38) and the gas distribution piston (36) are fixedly connected; a plurality of air holes (39) are arranged on the stabilizing piston (37) that communicate with both sides; when the second return spring (40) is in a natural state, the stabilizing piston (37) and the locking gas outlet (34) are misaligned; and when the gas inlet (33) is inhaled, the gas distribution piston (36) first drives the stabilizing piston (37) to move to block the locking gas outlet (34) and then continues to move and then misaligns with the forming gas outlet (35). ; 2. The exhaust pipe high pressure forming die according to claim 1, characterized in that: The lower die (2) is provided with a plurality of guide grooves (5), and linear bearings (6) are fixedly installed in the guide grooves (5). The upper die (1) is provided with an optical axis (7) that matches and slides with the linear bearings (6). The upper die (1) is slidably installed on the lower die (2) through the matching of the optical axis (7) and the linear bearings (6).

3. The exhaust pipe internal high pressure forming die according to claim 2, characterized in that: The optical axis (7) comprises a fixed portion (8) and a sliding portion (9), the diameter of the fixed portion (8) being larger than that of the sliding portion (9), the upper die (1) being provided with a mounting hole (10) matching the diameter of the sliding portion (9), the upper die (1) being fixedly provided with an upper pad (11) on a side away from the lower die (2), the sliding portion (9) of the optical axis (7) passing through the mounting hole (10) is clamped and fixed to the fixed portion (8) of the optical axis (7) by the cooperation of the upper pad (11) and the upper die (1), the sliding portion (9) of the optical axis (7) and the linear bearing (6) being slidably cooperated; the lower die (2) being fixedly provided with a lower pad (13) on a side away from the upper die (1), a positioning block (14) being fixedly provided on the lower pad (13), and a positioning groove matching and inlaid with the positioning block (14) being provided on a side of the lower die (2) and the lower pad (13) in contact.

4. The exhaust pipe internal high pressure forming die according to claim 3, characterized in that: The blocking punch (3) and the inflation punch (4) both include a mounting seat (16), and the mounting seat (16) is mounted with a pin seat (17) for inserting into the exhaust pipe through a threaded connection; the forming air channel (15) extends from one side of the mounting seat (16) of the inflation punch (4) to the end of the pin seat (17) of the inflation punch (4), and a sealing gasket (18) surrounding the forming air channel (15) is provided at the connection between the mounting seat (16) of the inflation punch (4) and the pin seat (17).

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