Pipe fitting row hole inner flanging die

Abstract

The utility model relates to the technical field of flanging dies, and discloses a pipe fitting row hole inner flanging die which comprises an upper die assembly and a lower die assembly which are oppositely arranged. The upper die assembly comprises an upper die base and a hole flanging male die, and the hole flanging male die is arranged on the upper die base. The lower die assembly comprises a lower die base, a positioning support and a hole flanging female die capable of being arranged in a pipe fitting in a sleeved mode, the positioning support is arranged on the top of the lower die base, and the hole flanging female die is rotationally connected with the positioning support. In the flanging process, the hole flanging female die can be sleeved with the pre-punched pipe fitting only by rotating the hole flanging female die and moving the hole flanging female die out of the positioning support, operation is easy, the loading and unloading time is saved, and the machining efficiency is high.

Description

Technical Field

[0001] The utility model relates to the technical field of flanging dies, and more specifically, to a pipe fitting multi-hole internal flanging die. Background Art

[0002] A water distributor is mainly used for water flow distribution in pipelines and is an important pipeline device widely used in industrial production, residential drainage, geothermal heating and other fields. Multiple internal flanging holes are arranged on the side wall of a square pipe fitting water distributor, and the inner wall of the holes adopts a thread structure for connecting shunt pipelines. The product has a beautiful appearance and exquisite craftsmanship and is a common type in water distributors. During the production process of the water distributor, it is first necessary to pre-punch the pipe material, and then perform internal flanging on the basis of the pre-punched holes. In the prior art, as disclosed in the utility model patent with the authorization publication number of CN203155841U, a large-hole high-precision flanging device for pipe fittings is disclosed, including: an upper die base and a lower die base arranged oppositely, a lower fixing plate is arranged on the lower die base, a mandrel fixing seat is arranged on the lower fixing plate, one end of a mandrel is fixedly connected to the mandrel fixing seat, a blanking seat is connected to the other end of the mandrel, a flanging hole penetrating the mandrel is formed in the blanking seat, an upper fixing plate is arranged on the upper die base, and a flanging punch matched with the flanging hole is fixedly arranged on the upper fixing plate. Through the above device, the multi-hole internal flanging of circular pipe fittings can be realized. However, when using this die to process pipe fittings, it is necessary to insert the workpiece to be processed into the mandrel fixing seat, and the loading and unloading are difficult, and the processing efficiency is low. Summary of the Utility Model

[0003] Aiming at the problems of difficult loading and unloading and low processing efficiency when processing the internal flanging holes of pipe fittings in the prior art solution, the utility model provides a pipe fitting multi-hole internal flanging die, which directly sleeved the pipe fitting on the flanging female die, and the loading and unloading are simple and fast, and the processing efficiency is high.

[0004] In order to solve the above technical problems, the utility model provides the following technical solutions:

[0005] A pipe fitting multi-hole internal flanging die includes an upper die assembly and a lower die assembly arranged oppositely; the upper die assembly includes an upper die base and a flanging punch, and the flanging punch is arranged on the upper die base; the lower die assembly includes a lower die base, a positioning support and a flanging female die that can be sleeved inside the pipe fitting, the positioning support is arranged on the top of the lower die base, and the flanging female die is rotatably connected to the positioning support.

[0006] A flanging die for the row of holes of a pipe fitting provided by the utility model fixes the position of the hole flanging punch through an upper die base, and a positioning support for fixing the position of the hole flanging die is arranged on a lower die base. During the die closing process, the upper die assembly descends, and the pre-punched holes on the pipe fitting are flanged through the cooperation of the hole flanging die and the hole flanging punch. The hole flanging die is rotatably connected to the positioning support. When loading, the hole flanging die is rotated to move it out of the positioning support, and the pipe fitting to be processed is sleeved on the hole flanging die. Subsequently, the hole flanging die is rotated and moved into the positioning support to complete the loading work. After flanging, the upper die base and the lower die base move away from each other, the hole flanging punch and the hole flanging die are separated, and the hole flanging die is rotated to move it out of the positioning support, and then the processed pipe fitting can be taken out. The overall structure of the die is simple, the loading and unloading processes are smooth and fast, the time for loading and unloading is saved, and the processing efficiency of the row of holes flanging of the pipe fitting is improved.

[0007] Further, the hole flanging die is provided with a connecting end and a rotating end. A through hole is arranged on the connecting end, and a positioning groove is arranged on the rotating end. The positioning supports are in two groups. One group of the positioning supports is provided with a rotating pin rotatably connected to the through hole, and the other group of the positioning supports is provided with a ball head plunger matched with the positioning groove. The connecting end realizes the rotational connection between the hole flanging die and the positioning support through the cooperation of the through hole and the rotating pin, ensuring the smooth progress of the rotation process and facilitating loading and unloading. The rotating end is locked with the hole flanging die by the engagement of the ball head plunger and the positioning groove, realizing the locking of the hole flanging die.

[0008] Further, a handle screw is arranged on the rotating end, and the handle screw protrudes from the positioning support. Adding a handle screw protruding from the positioning support on the rotating end makes it more convenient to rotate the hole flanging die, improves the convenience of using the die, and saves processing time.

[0009] Further, the connecting end is provided with a positioning block and a positioning screw for fixing the position of the positioning block. The positioning screw fixes the positioning block on the connecting end. When loading, the pipe fitting is manually sleeved on the hole flanging die, and the pipe fitting can be pushed against the positioning block to achieve side positioning, forcing the position of the pre-punched hole of the pipe fitting to be aligned with the opening position of the hole flanging die.

[0010] Further, a groove is arranged inside the positioning support, and the connecting end is arranged in the groove. The hole flanging die is arranged in the groove inside the positioning support. During the loading and unloading process, the hole flanging die only needs to be moved out of the groove, reducing the rotation range of the hole flanging die and improving the loading and unloading speed.

[0011] Further, a supporting plate is provided between the positioning supports. The height of the supporting plate is lower than that of the flanging die. A plurality of springs are provided on the lower die base. The supporting plate is connected to the springs. A limiting rod is provided on the upper die base and can abut against the supporting plate to adjust the position of the supporting plate. The supporting plate with a height lower than that of the flanging die is provided between the positioning supports mainly to lift the pipe fitting during the unloading process and improve the unloading efficiency. During mold closing, the upper die base moves downward, the limiting rod abuts against the supporting plate, driving the supporting plate to move downward, and the springs between the supporting plate and the lower die base are compressed. The supporting plate is separated from the bottom of the pipe fitting to avoid affecting the flanging process. During mold opening, the upper die base moves upward. Due to the frictional force between the flanging punch and the pipe fitting, the flanging punch will drive the pipe fitting to move upward synchronously until the inner wall of the bottom side of the pipe fitting contacts the flanging die. Subsequently, under the action of the flanging die, the pipe fitting stops rising and separates from the flanging punch. Under the action of the self-gravity of the pipe fitting, the pipe fitting hangs on the flanging die, and the inner wall of the top of the pipe fitting contacts the flanging die. As the upper die base continues to move upward, the limiting rod also moves upward synchronously and gradually separates from the supporting plate, no longer compressing the springs. The supporting plate lifts the pipe fitting upward under the action of the springs, making the inner flanging flange of the pipe fitting higher than the flanging die, avoiding interference between the flanging part and the flanging die, and facilitating the removal of the processed pipe fitting.

[0012] Further, an equal-height sleeve for restricting the rebound stroke of the supporting plate is provided between the supporting plate and the lower die base. The equal-height sleeve can restrict the rebound stroke of the supporting plate, keep the pipe fitting at a position where the flanging flange is higher than the flanging die and the bottom of the pipe fitting does not contact the flanging die, reduce the resistance when the pipe fitting is removed from the mold, and thus smoothly and quickly complete the unloading.

[0013] Further, a plurality of flanging punches with different lengths are provided on the upper die base. The arrangement of a plurality of flanging punches on the upper die base can simultaneously complete the flanging process at multiple pre-punched hole positions on the pipe fitting, improve the working efficiency. At the same time, the lengths of the flanging punches in each group are different, and the flanging process is carried out in sequence, effectively reducing the flanging impact force of the perforated holes, reducing the pressure on the flanging die, and improving the durability of the parts.

[0014] Further, the cross-section of the flanging die is a first square, and the cross-section of the pipe fitting is a second square. The length and width of the first square are both smaller than the length and width of the second square. The size of the first square cross-section is slightly smaller than that of the second square cross-section, which is convenient for directly sleeving the square pipe fitting on the flanging die and keeping the loading and unloading process smooth.

[0015] Further, a guide sleeve is provided on the upper die base, and a guide post that is connected and matched with the guide sleeve is provided on the lower die base or a guide post is provided on the upper die base, and a guide sleeve connected to the guide post is provided on the lower die base. The connection of the guide post and the guide sleeve realizes the guiding between the upper die assembly and the lower die assembly, controls the approach of the upper die base to the lower die base in a fixed direction, and improves the processing accuracy of the flanging process.

[0016] Compared with the prior art, the utility model has the following beneficial effects:

[0017] 1. The flanging concave die is rotatable, and the pipe fitting can be directly sleeved on the flanging concave die. The opening and closing actions are simple, and the loading and unloading of the pipe fitting are convenient during the flanging processing cycle, reducing the loading and unloading time and improving the processing efficiency.

[0018] 2. The position of the supporting plate is controlled by the spring and the equal-height sleeve. During the unloading process, the supporting plate can float up to support the pipe fitting, making the flanging flange leave the inner hole of the concave die, ensuring the smooth and safe unloading process of the pipe fitting.

[0019] 3. Multiple groups of flanging punches with stepped heights are provided, which improves the processing efficiency and effectively reduces the impact force of synchronous flanging of the row of holes, reduces the pressure on the concave die, and improves the durability of the parts. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present utility model. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0021] Figure 1 It is the open die state diagram of the pipe fitting row hole inner flanging die of the present utility model;

[0022] Figure 2 It is the sectional view of the open die state of the pipe fitting row hole inner flanging die of the present utility model;

[0023] Figure 3 It is the closed die state diagram of the pipe fitting row hole inner flanging die of the present utility model;

[0024] Figure 4 It is the exploded view of the pipe fitting row hole inner flanging die of the present utility model;

[0025] Description of the Reference Numerals:

[0026] 1. Upper die assembly; 11. Upper die base; 12. Flanging punch; 13. Guide sleeve; 14. Limit rod; 15. Fixed plate; 2. Lower die assembly; 21. Lower die base; 22. Positioning support; 221. Groove; 222. Rotating pin; 223. Ball head plunger; 23. Flanging concave die; 231. Connection end; 232. Rotating end; 233. Positioning groove; 234. Positioning block; 235. Positioning screw; 236. Handle screw; 24. Guide post; 25. Supporting plate; 26. Spring; 27. Equal-height sleeve. Detailed Embodiments

[0027] To enable those skilled in the art to better understand the technical solution of the present utility model, the following will further introduce the present utility model in detail with reference to the accompanying drawings.

[0028] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0029] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present utility model, "a plurality" means two or more, unless otherwise specifically defined. In addition, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0030] The technical solutions in the embodiments of the present utility model will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0031] Embodiment 1

[0032] As Figure 1As shown in the figure, the flanging die for the perforated pipe fittings in this embodiment includes an upper die assembly 1 and a lower die assembly 2 which are arranged opposite to each other; the upper die assembly 1 includes an upper die base 11 and a hole-flanging punch 12, and the hole-flanging punch 12 is arranged on the upper die base 11; the lower die assembly 2 includes a lower die base 21, a positioning support 22 and a hole-flanging die 23 that can be sleeved inside the pipe fitting. The positioning support 22 is arranged on the top of the lower die base 21, and the hole-flanging die 23 is rotatably connected to the positioning support 22. The positioning support 22 for fixing the position of the hole-flanging die 23 is provided on the lower die base 21, which can not only ensure the alignment of the hole-flanging die 23 and the hole-flanging punch 12 in the vertical direction, but also bear the pressure exerted on the hole-flanging die 23 during the flanging process and protect the structure of the hole-flanging die 23. In the mold opening stage, first rotate the hole-flanging die 23 to move one end out of the positioning support 22, and then directly sleeve the pipe fitting to be processed on the hole-flanging die 23. Subsequently, enter the mold closing stage, rotate the hole-flanging die 23 to make it return to the positioning support 22, control the upper die base 11 and the hole-flanging punch 12 to move downward, and the hole-flanging punch 12 and the hole-flanging die 23 cooperate to complete the flanging process of the pre-punched hole of the pipe fitting. The hole-flanging die 23 is rotatable, which is convenient for directly sleeving the pipe fitting on the hole-flanging die 23. The opening and closing actions are simple, and it is convenient for loading and unloading materials during the hole-flanging processing cycle, reducing the loading and unloading time and improving the processing efficiency.

[0033] As Figure 3 shown in the figure, the hole-flanging die 23 in this embodiment is provided with a connecting end 231 and a rotating end 232. A through hole is provided on the connecting end 231, and a positioning groove 233 is provided on the rotating end 232. A rotating pin 222 rotatably connected to the through hole is provided on one side of the positioning support 22, and a ball plunger 223 that cooperates with the positioning groove 233 is provided on the other side. The hole-flanging die 23 rotates around the rotating pin 222 on the connecting end 231. When loading and unloading materials, rotate the hole-flanging die 23 so that the rotating end 232 is away from the positioning support 22; during the hole-flanging process, rotate the hole-flanging die 23 to make the rotating end 232 enter the positioning support 22. A ball plunger 223 is provided on the positioning support 22, and the ball plunger 223 pops up and engages with the positioning groove 233 provided on the rotating end 232 to fix the overall position of the hole-flanging die 23 and ensure the alignment of the hole position of the hole-flanging die 23 and the hole-flanging punch 12. The cooperation between the rotating pin 222 and the through hole ensures the smooth rotation process of the hole-flanging die 23, and the ball plunger 223 and the positioning groove 233 achieve the circumferential locking during the rotation process of the hole-flanging die 23, making the rotation and fixing process of the hole-flanging die 23 smoother and faster, reducing the loading and unloading time and further improving the processing efficiency.

[0034] In the positioning support 22 in this example, a groove 221 is provided inside. The flanging female die 23 is arranged in the groove 221. To further facilitate the rotation of the flanging female die 23, the positioning support 22 can be set as a U-shaped structure, so that the length of the positioning support 22 on the side close to the upper die base 11 is less than the length on the side close to the lower die base 21. During the flanging process, only the rotating end 232 needs to be moved out of the groove 221, which can reduce the rotation angle of the flanging female die during the loading and unloading processes and improve the loading and unloading speed.

[0035] As Figure 4 shown, the cross-section of the flanging female die in this embodiment is a first square, and the cross-section of the pipe fitting is a second square. Both the length and width of the first square are smaller than the length and width of the second square. Controlling the cross-sectional shape of the flanging female die 23 to be the same as the cross-sectional shape of the processed pipe fitting can enhance the stability during the processing. Both the length and width of the first square are smaller than those of the second square, which is convenient for directly sleeving the pipe fitting on the flanging female die 23, facilitating operation and reducing the loading and unloading time.

[0036] To facilitate loading and unloading and maintain processing stability, the cross-sectional shape of the flanging female die 23 can be adaptively adjusted according to the cross-sectional shape of the processed pipe fitting, so that the cross-sectional shape of the flanging female die 23 is the same as the cross-sectional shape of the pipe fitting. For example, when processing circular pipe fittings, the cross-section of the flanging female die 23 can also be set as a circle.

[0037] A handle screw 236 is provided on the rotating end 232 in this embodiment. The handle screw 236 is perpendicular to the flanging female die 23 and protrudes from the positioning support 22. The rotation of the flanging female die 23 is controlled by the handle screw 236, which is convenient for controlling the position of the flanging female die 23, can further reduce the operation difficulty of the die, improve the convenience of using the die, and improve the processing efficiency.

[0038] A guide bushing 13 is provided on the upper die base 11 in this embodiment, and a guide post 24 that is cooperatively connected with the guide bushing 13 is provided on the lower die base 21. The guide post 24 and the guide bushing 13 can also be arranged on the upper die base 11, and the guide bushing 13 connected to the guide post 24 is arranged on the lower die base 21. The cooperation between the guide post 24 and the guide bushing 13 guides the movement of the upper die assembly 1 and the lower die assembly 2, making the position of the flanging more accurate and improving the flanging quality.

[0039] The upper die assembly 1 in this embodiment further includes a fixing plate 15. The fixing plate 15 is arranged at the bottom of the upper die base 11. The flanging punch 12 and the limiting rod 14 are both arranged on the fixing plate 15. Arranging the fixing plate 15 on the upper die base 11 is used to fix the position of the flanging punch 12, which can increase the connection reliability between the flanging punch 12 and the upper die base 11, avoid bending and deflection of the flanging punch 12 during the processing, and improve the processing accuracy of the die.

[0040] Embodiment Two

[0041] AsFigure 2 , Figure 3 As shown in Figure 3 , this embodiment is similar to the first embodiment. The difference is that a support plate 25 is provided between the positioning supports 22. The height of the support plate 25 is lower than that of the flanging female die 23. A plurality of springs 26 for lifting the support plate and equal-height sleeves 27 for restricting the rebound stroke of the support plate 25 are provided between the lower die base 21 and the support plate 25. A limit rod 14 that can abut against the support plate 25 to adjust the position of the support plate 25 is provided on the upper die base 11.

[0042] When the mold is closed and moves downward, the distance between the upper die assembly 1 and the lower die assembly 2 decreases. The limit rod 14 abuts against the support plate 25, the height of the support plate 25 drops, and the springs 26 are synchronously compressed, creating a gap between the support plate 25 and the pipe fitting, and the pipe fitting is no longer supported by the support plate 25. The pipe fitting slides down by its own weight and hangs on the flanging female die 23. The mold continues to move downward, and the springs 26 continue to be compressed until all the flanging punch dies 12 enter the holes of the flanging female die 23, completing the flanging process of the pipe fitting.

[0043] After the flanging is completed, the upper die assembly 1 retracts, that is, the springs 26 rebound, driving the support plate 25 to move upward. At the same time, under the action of friction, the pipe fitting will move upward with the flanging punch die 12. The pipe fitting continues to move upward until the inner wall of the bottom side of the pipe fitting contacts the bottom of the flanging female die 23. The flanging female die 23 provides a downward demolding force to achieve the strong separation of the flanging punch die 12 and the pipe fitting. After separation, the pipe fitting hangs on the flanging female die 23 under the action of gravity. The upper die assembly 1 continues to move upward, the limit rod 14 separates from the support plate 25, and the support plate 25 starts to lift the pipe fitting. At the same time, the equal-height sleeves 27 will limit the height of the support plate 25 and control its rebound stroke. After the support plate 25 lifts the pipe fitting to a position where the inner flanging flange of the pipe fitting is higher than the inner hole of the flanging female die 23 and the inner side of the bottom of the pipe fitting does not contact the bottom surface of the flanging female die 23, it remains at a constant height under the action of the equal-height sleeves 27 and the springs 26. The support plate supports the pipe fitting, preventing interference between the pipe fitting and the flanging female die 23, facilitating the removal of the pipe fitting, and further reducing the time required for unloading.

[0044] Embodiment Three

[0045] As Figure 2 shown in Figure 2 , this embodiment is similar to the first embodiment. The difference is that multiple groups of flanging punch dies 12 are provided on the upper die base 11 in this embodiment. During the flanging process, multiple pre-punched holes at different positions on the pipe fitting can be flanged simultaneously, improving the processing efficiency.

[0046] In this embodiment, the lengths of each group of flanging punch dies 12 are different. The order of the flanging process for the perforated holes can be adjusted by changing the lengths of the flanging punch dies 12. The flanging punch dies 12 with different lengths cooperate with the flanging female die 23 in sequence, reducing the flanging force on the flanging female die 23, improving the durability of the part, and increasing the service life of the flanging female die 23.

[0047] Embodiment 4

[0048] As shown Figure 4 in the figure, this embodiment is similar to Embodiment 1. The difference is that the connecting end 231 in this embodiment is provided with a positioning block 234 and a positioning screw 235 for fixing the position of the positioning block 234. By loosening the positioning screw 235, the position of the positioning block 234 on the flanging female die 23 can be adjusted; by tightening the positioning screw 235, the relative position of the positioning screw 235 and the flanging female die 23 can be fixed. When the pipe fitting is sleeved on the flanging female die 23, one end of the pipe fitting is made to closely adhere to the positioning block 234 to achieve side positioning, and the pre-punched hole position of the pipe fitting, the preset hole position of the flanging female die 23, and the flanging punch 12 are aligned with each other, improving the processing accuracy of the flanging process.

[0049] In the specific content of the above specific implementation manner, each technical feature can be combined arbitrarily without contradiction. For the sake of concise description, not all possible combinations of the above technical features are described. However, as long as the combinations of these technical features do not conflict, they should all be considered to be within the scope described in this specification.

[0050] Obviously, the above embodiments of the present invention are merely examples given for clearly explaining the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made on the basis of the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A pipe hole inner flanging die, characterized in that: The invention comprises an upper die assembly (1) and a lower die assembly (2) which are arranged opposite to each other; the upper die assembly (1) comprises an upper die base (11) and a hole-turning punch (12), wherein the hole-turning punch (12) is arranged on the upper die base (11); the lower die assembly (2) comprises a lower die base (21), a positioning support (22) and a hole-turning die (23) which can be sleeved in a pipe fitting, wherein the positioning support (22) is arranged on the top of the lower die base (21), and the hole-turning die (23) is rotatably connected to the positioning support (22).

2. A pipe hole inner flanging die according to claim 1, characterized in that: The hole-turning die (23) is provided with a connecting end (231) and a rotating end (232); the connecting end (231) is provided with a through hole; the rotating end (232) is provided with a positioning groove (233); the positioning supports (22) are divided into two groups, one group of the positioning supports (22) is provided with a rotating pin (222) rotatably connected to the through hole; the other group of the positioning supports (22) is provided with a ball plunger (223) that cooperates with the positioning groove (233).

3. A pipe hole inner flanging die according to claim 2, characterized in that: The rotating end (232) is provided with a handle screw (236), and the handle screw (236) protrudes from the positioning support (22).

4. A pipe hole inner flanging die according to claim 2, characterized in that: The connection end (231) is provided with a positioning block (234) and a positioning screw (235) for fixing the position of the positioning block (234).

5. The pipe hole inner flanging die according to claim 2, characterized in that: A groove (221) is provided inside the positioning support (22), and the connecting end (231) is arranged in the groove (221).

6. The pipe hole inner flanging die according to claim 1, characterized in that: A support plate (25) is provided between the positioning supports (22), the height of the support plate (25) is lower than the height of the punching die (23), a plurality of springs (26) are provided on the lower die seat (21), the support plate (25) is connected to the springs (26), and a limiting rod (14) is provided on the upper die seat (11) which can abut against the support plate (25) to adjust the position of the support plate (25).

7. A pipe hole inner flanging die according to claim 6, characterized in that: A sleeve (27) of equal height for limiting the rebound stroke of the support plate (25) is provided between the support plate (25) and the lower die seat (21).

8. A pipe hole inner flanging die according to any one of claims 1 to 5, characterized in that: The upper die seat (11) is provided with a plurality of groups of punches (12) with different lengths.

9. A pipe hole inner flanging die according to any one of claims 1 to 5, characterized in that: The cross section of the punching die (23) is a first square, the cross section of the pipe is a second square, and the length and width of the first square are both smaller than the length and width of the second square.

10. A pipe hole inner flanging die according to any one of claims 1 to 5, characterized in that: The upper die base (11) is provided with a guide sleeve (13), and the lower die base (21) is provided with a guide column (24) which is matched and connected with the guide sleeve (13); or the upper die base (11) is provided with a guide column (24), and the lower die base (21) is provided with a guide sleeve (13) which is connected with the guide column (24).

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