Expansion-shrinkage drawing forming process for pipe with different walls

Abstract

The invention discloses an expansion-shrinkage drawing forming process of a different-wall pipe in the technical field of different-wall pipe machining. A machine frame is included, a pipe blank is arranged in the machine frame, a core rod is arranged in the pipe blank, the rear end of the core rod is fixedly connected with the machine frame, a groove is formed in the front end of the machine frame, and the diameter of the groove is larger than the inner diameter of the pipe blank; a pushing and extruding mechanism is arranged at the pipe expanding position of the outer surface of the pipe blank and used for being matched with the multiple core rods to finish multiple times of pipe expanding of the pipe blank. A clamping mechanism is arranged in the rack and is used for clamping the pipe wall at the front end of the pipe blank without influencing the core rod to enter the pipe blank from the front end of the pipe blank; a drawing mechanism is arranged on the rack, and the drawing mechanism is used for pulling the pipe blank to move forwards after the clamping mechanism clamps the pipe blank; according to the device, a plurality of core rods which are gradually enlarged are continuously used, so that the diameter of the pipe blank can be gradually expanded, the diameter expanding effect of the pipe blank can be effectively improved, and meanwhile, the damage probability of the pipe blank can be greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of processing different-wall tubes, in particular to an expansion and contraction drawing forming process for different-wall tubes. Background Art

[0002] Different-wall tubes, also known as different-wall special-shaped tubes, are special-shaped seamless steel tubes with different wall thicknesses. The diameters of different parts are different. The more common processing method is to expand the diameter by drawing. When expanding the diameter, the mandrel is inserted into the tube, and then one end of the tube blank is clamped with a clamp. Then, the tube blank is pulled and the diameter expansion is completed under the action of the mandrel.

[0003] When expanding the diameter of a different-walled tube, if the expansion value is large, it is easy to damage the different-walled tube if it is completed in one go, causing the expanded diameter part of the different-walled tube to crack. Therefore, multiple core rods that are successively larger are usually used for multiple expansions. The expansion value each time is small, which can effectively prevent the damage of the different-walled tube. When replacing the core rod, the core rod needs to be inserted from the clamped end of the different-walled tube. At this time, the different-walled tube needs to be removed from the clamping piece. After the core rod is inserted into the different-walled tube, the different-walled tube needs to be fixed to the clamping piece again. It is necessary to repeat the above operation multiple times to complete the expansion of a different-walled tube. The operation is relatively complicated, time-consuming and labor-intensive. Summary of the invention

[0004] The purpose of the present invention is to provide a process for expansion and contraction drawing of a different-wall tube to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a process for expansion and contraction drawing of a tube with different wall, comprising a frame, a tube blank is arranged in the frame, a core rod is arranged inside the tube blank, the rear end of the core rod is fixedly connected to the frame and a groove is provided at the front end of the frame, the diameter of the groove is larger than the inner diameter of the tube blank; a pushing mechanism is provided at the expansion position of the outer surface of the tube blank, the pushing mechanism is used to cooperate with multiple core rods to complete multiple expansions of the tube blank; a clamping mechanism is provided in the frame, the clamping mechanism is used to clamp the tube wall at the front end of the tube blank without affecting the mandrel rod from the front end of the tube blank into the tube blank; a drawing mechanism is provided on the frame, the drawing mechanism is used to pull the tube blank forward after the clamping mechanism clamps the tube blank.

[0006] Furthermore, the clamping mechanism includes a sliding frame, which is slidably connected to the frame and has four first clamping blocks inside the sliding frame; the four first clamping blocks are distributed in a circular array inside the sliding frame, and the distance between two relative first clamping blocks is greater than the outer diameter of the tube blank; the sliding frame is provided with an adjusting mechanism, which is used to simultaneously drive the four first clamping blocks to move to a position close to or away from the tube blank; the first clamping block is provided with a fastening mechanism, which is used to cooperate with the first clamping block to clamp the tube wall of the tube blank.

[0007] Furthermore, the adjustment mechanism includes a bevel gear ring, which is sleeved on the sliding frame and is rotatably connected to the sliding frame; a handle is fixedly connected to the bevel gear ring; a first threaded rod is fixedly connected to the first clamping block, a sliding groove is provided on the surface of the first threaded rod and the sliding groove on the first threaded rod is slidably connected to the sliding frame; the first threaded rod has self-locking properties and a first bevel gear is threadedly connected to the first threaded rod, and the first bevel gear is rotatably connected to the outer surface of the sliding frame; the bevel gear ring is meshed with four first bevel gears at the same time.

[0008] Furthermore, the fastening mechanism includes a second clamping block, which is rotatably connected to the first clamping block and the distance between the second clamping block and the first clamping block is equal to the thickness of the tube wall of the tube blank; the second clamping block is fixedly connected to a worm gear at two positions connected to the first clamping block; the first clamping block is rotatably connected to two worms, and the two worms are respectively engaged with two worm gears; the sliding frame is provided with a driving mechanism, which is used to drive the four second clamping blocks to rotate simultaneously.

[0009] Furthermore, the driving mechanism includes a fixed frame, which is located inside the sliding frame and fixedly connected to the sliding frame; an outer ring gear is rotatably connected to the fixed frame; a second bevel gear is fixedly connected to the end of the worm gear away from the worm wheel, a third bevel gear is meshed at the rear of the second bevel gear, a first gear is fixedly connected to the rear end of the third bevel gear, and the first gear is meshed with the outer ring gear; a rotating mechanism is provided on the sliding frame, and the rotating mechanism is used to drive the outer ring gear to rotate when the sliding frame moves to the front position of the frame.

[0010] Furthermore, the rotating mechanism includes four second gears, the four second gears are all rotatably connected to the fixed frame and the four second gears are all meshed with the outer gear ring; a second threaded rod is fixedly connected to the front end of the second gear, the second threaded rod does not have self-locking properties and a threaded barrel is provided in front of the second threaded rod, the threaded barrel is threadedly connected to the second threaded rod and the threaded barrel is fixedly connected to the frame.

[0011] Furthermore, the pulling mechanism includes two first cylinders, which are symmetrically distributed at upper and lower sides of the rear of the frame and are both fixedly connected to the frame; the telescopic ends of the first cylinders are fixedly connected to the sliding frame.

[0012] Furthermore, the pushing mechanism includes a fixed frame, which is fixedly connected to the frame and is relatively perpendicular to the frame; a sliding plate is slidably connected inside the fixed frame, and three pushing grooves are provided on the sliding plate; a second cylinder is fixedly connected to the right side of the fixed frame, and the telescopic end of the second cylinder is fixedly connected to the sliding plate.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses a drawing mechanism to pull the tube blank clamped by the clamping mechanism forward, and when the tube blank moves forward, the initial diameter expansion can be completed under the internal and external actions of the pushing mechanism and the tube blank; when the drawing mechanism pulls the tube blank to the frontmost position, the part of the rear end of the tube blank that needs to be expanded is just separated from the mandrel, and the tube blank completes the first diameter expansion; the smaller mandrel is removed, and then the drawing mechanism is driven to drive the tube blank to move backward and reset; the larger mandrel is inserted into the tube blank through the groove again and finally the rear end of the larger mandrel is fixed on the frame, and then the above steps are repeated again. By continuously using multiple gradually increasing mandrels, the gradual diameter expansion of the tube blank can be completed, which can effectively improve the effect of the tube blank diameter expansion and greatly reduce the probability of damage to the tube blank.

[0014] When the present invention drives the tube blank to move to the rearmost position through the sliding frame, the tube blank completes one diameter expansion, and the second threaded rod on the sliding frame will be inserted into the threaded barrel again. Under the action of the threaded barrel, the second threaded rod will start to rotate. When the second threaded rod rotates, it will drive the second clamping block to rotate relative to the first clamping block and separate from the inner wall of the tube blank. At this time, the second clamping block is not inside the tube blank, and a larger core rod can be inserted into the tube blank. The core rod will not be blocked by the second clamping block. Therefore, there is no need to remove the tube blank when installing the core rod, which can effectively improve the efficiency of tube blank diameter expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a rear view structural schematic diagram of the present invention; Figure 3 It is a schematic diagram of the split structure of the present invention; Figure 4 It is a structural schematic diagram of the fixing frame in the present invention; Figure 5 It is a schematic cross-sectional structural diagram of the sliding plate in the present invention; Figure 6 It is a structural schematic diagram of the frame in the present invention; Figure 7 It is a structural schematic diagram of the sliding frame in the present invention; Figure 8 It is a schematic structural diagram of the sliding frame in the present invention from a second viewing angle; Fig. 9 It is a schematic structural diagram of the first clamping block in the present invention.

[0016] In the accompanying drawings, the components represented by the reference numerals are listed as follows: 1. Frame; 2. Tube; 3. Mandrel; 4. Groove; 5. Sliding frame; 6. First clamping block; 7. Bevel gear ring; 8. Handle; 9. First threaded rod; 10. Slide groove; 11. First bevel gear; 12. Second clamping block; 13. Worm gear; 14. Worm; 15. Fixed frame; 16. External gear ring; 17. Second bevel gear; 18. Third bevel gear; 19. First gear; 20. Second gear; 21. Second threaded rod; 22. Threaded barrel; 23. First cylinder; 24. Fixed frame; 25. Sliding plate; 26. Pushing groove; 27. Second cylinder. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1-Figure 9 The present invention provides a technical solution: a shrinkage drawing process for a different-wall tube, comprising a frame 1, a tube blank 2 is arranged in the frame 1, a mandrel 3 is arranged inside the tube blank 2, the rear end of the mandrel 3 is fixedly connected to the frame 1 and a groove 4 is provided at the front end of the frame 1, the diameter of the groove 4 is greater than the inner diameter of the tube blank 2; a pushing mechanism is provided at the tube expansion position on the outer surface of the tube blank 2, the pushing mechanism is used to cooperate with multiple mandrels 3 to complete multiple tube expansions of the tube blank 2; a clamping mechanism is provided in the frame 1, the clamping mechanism is used to clamp the tube wall at the front end of the tube blank 2 without affecting the mandrel 3 from the front end of the tube blank 2 into the tube blank 2; a drawing mechanism is provided on the frame 1, the drawing mechanism is used to pull the tube blank 2 forward after the clamping mechanism clamps the tube blank 2; During operation, the tube blank 2 to be expanded is clamped by the clamping mechanism, and then the smaller mandrel 3 is first inserted into the tube blank 2 from the groove 4, and finally the mandrel 3 passes through the rear end of the tube blank 2 and the rear end of the mandrel 3 is fixed on the frame 1; after the mandrel 3 is fixed, the front end of the mandrel 3 is pushed and squeezed at the position of the expanded diameter in the tube blank 2, and the drawing mechanism is started at this time, and the tube blank 2 clamped by the clamping mechanism is pulled forward by the drawing mechanism. When the tube blank 2 moves forward, the initial expansion can be completed under the internal and external action of the pushing mechanism and the tube blank 2; when the drawing mechanism pulls the tube blank 2 to the front end position, the part of the rear end of the tube blank 2 that needs to be expanded is just separated from the mandrel 3, and the tube blank 2 completes the first expansion; the smaller mandrel 3 is removed, and then the drawing mechanism is driven to drive the tube blank 2 to move backward and reset; the larger mandrel 3 is inserted into the tube blank 2 through the groove 4 again and finally the rear end of the larger mandrel 3 is fixed on the frame 1, and then the above steps are repeated again. By continuously using multiple gradually larger mandrels 3, the gradual expansion of the tube blank 2 can be completed, which can effectively improve the expansion effect of the tube blank 2 and greatly reduce the probability of damage to the tube blank 2.

[0019] like Figure 7-Figure 9 As shown, as a further solution of the present invention, the clamping mechanism includes a sliding frame 5, the sliding frame 5 is slidably connected to the frame 1 and four first clamping blocks 6 are arranged in the sliding frame 5; the four first clamping blocks 6 are distributed in the sliding frame 5 in a circumferential array, and the distance between two relative first clamping blocks 6 is greater than the outer diameter of the tube blank 2; the sliding frame 5 is provided with an adjustment mechanism, and the adjustment mechanism is used to simultaneously drive the four first clamping blocks 6 to move to a position close to the tube blank 2 or away from the tube blank 2; the first clamping block 6 is provided with a fastening mechanism, and the fastening mechanism is used to cooperate with the first clamping block 6 to clamp the tube wall of the tube blank 2; The adjustment mechanism includes a bevel gear ring 7, which is sleeved on the sliding frame 5 and is rotatably connected to the sliding frame 5; a handle 8 is fixedly connected to the bevel gear ring 7; a first threaded rod 9 is fixedly connected to the first clamping block 6, a sliding groove 10 is provided on the surface of the first threaded rod 9, and the sliding groove 10 on the first threaded rod 9 is slidably connected to the sliding frame 5; the first threaded rod 9 has self-locking properties and a first bevel gear 11 is threadedly connected to the first threaded rod 9, and the first bevel gear 11 is rotatably connected to the outer surface of the sliding frame 5; the bevel gear ring 7 is meshed with four first bevel gears 11 at the same time; During operation, when the tube blank 2 needs to be clamped, the bevel gear ring 7 is rotated by the handle 8. When the bevel gear ring 7 rotates, the four first bevel gears 11 meshing with it will be driven to rotate. When the first bevel gear 11 rotates, it will drive the first threaded rod 9 meshing with it to slide relative to the sliding frame 5. By controlling the rotation direction of the bevel gear ring 7, the first threaded rod 9 can be made to slide toward the direction close to the tube blank 2. When the first threaded rod 9 moves, it drives the first clamping block 6 connected to it to move. When the four first clamping blocks 6 are all moved to fit the outer surface of the tube blank 2 and clamp the tube blank 2, the rotation of the bevel gear ring 7 can be stopped at this time, and the tube blank 2 is clamped by the four first clamping blocks 6.

[0020] like Figure 6-Figure 9 As shown, as a further solution of the present invention, the fastening mechanism includes a second clamping block 12, the second clamping block 12 is rotatably connected to the first clamping block 6, and the distance between the second clamping block 12 and the first clamping block 6 is equal to the thickness of the tube wall of the tube blank 2; the second clamping block 12 is fixedly connected to two positions connected to the first clamping block 6 with a worm gear 13; the first clamping block 6 is rotatably connected to two worms 14, and the two worms 14 are respectively engaged with the two worm gears 13; the sliding frame 5 is provided with a driving mechanism, and the driving mechanism is used to simultaneously drive the four second clamping blocks 12 to rotate; The driving mechanism includes a fixed frame 15, which is located inside the sliding frame 5 and fixedly connected to the sliding frame 5; an outer gear ring 16 is rotatably connected to the fixed frame 15; a second bevel gear 17 is fixedly connected to the end of the worm 14 away from the worm wheel 13, a third bevel gear 18 is meshed at the rear of the second bevel gear 17, a first gear 19 is fixedly connected to the rear end of the third bevel gear 18, and the first gear 19 is meshed with the outer gear ring 16; a rotating mechanism is provided on the sliding frame 5, and the rotating mechanism is used to drive the outer gear ring 16 to rotate when the sliding frame 5 moves to the front position of the frame 1; The rotating mechanism includes four second gears 20, which are all rotatably connected to the fixing frame 15 and meshed with the outer gear ring 16; a second threaded rod 21 is fixedly connected to the front end of the second gear 20, the second threaded rod 21 does not have self-locking property, and a threaded barrel 22 is provided in front of the second threaded rod 21, the threaded barrel 22 is threadedly connected to the second threaded rod 21, and the threaded barrel 22 is fixedly connected to the frame 1; During operation, when the tube blank 2 is clamped by the four first clamping blocks 6, the initial position of the sliding frame 5 is at the front of the frame 1, and then the sliding frame 5 is driven to move backward. When the sliding frame 5 moves backward, it will drive the four second threaded rods 21 to move backward. When the second threaded rod 21 moves backward, the second threaded rod 21 will gradually disengage from the threaded cylinder 22. Under the action of the threaded cylinder 22, the second threaded rod 21 will start to rotate. When the second threaded rod 21 rotates, it drives the second gear 20 connected thereto to rotate. When the four second gears 20 rotate, they drive the outer gear ring 16 to rotate. When the outer gear ring 16 rotates, it drives the four first gears 19 meshing therewith to rotate. When the first gear 19 rotates, it drives the third bevel gear 18 connected thereto to rotate. When the third bevel gear 18 rotates, it drives the fourth bevel gear 19 meshing therewith to rotate. The second bevel gear 17 rotates, and when the second bevel gear 17 rotates, it will drive the worm 14 to rotate, and the worm 14 will drive the worm wheel 13 to rotate, and the worm wheel 13 will drive the second clamping block 12 to rotate relative to the first clamping block 6 to clamp the tube wall of the tube blank 2; when it is necessary to pull the tube blank 2 backward to expand the diameter, the first clamping block 6 and the second clamping block 12 can stably pull the tube blank 2 backward; when the sliding frame 5 drives the tube blank 2 to move to the rearmost position, the tube blank 2 completes a diameter expansion, and the second threaded rod 21 on the sliding frame 5 will be inserted into the threaded barrel 22 again, and the second clamping block 12 will rotate relative to the first clamping block 6 and disengage from the inner wall of the tube blank 2. At this time, the second clamping block 12 is not inside the tube blank 2, and a larger core rod 3 can be inserted into the tube blank 2, and the core rod 3 will not be blocked by the second clamping block 12.

[0021] like Figure 1 , Figure 6 As shown, as a further solution of the present invention, the drawing mechanism includes two first cylinders 23, the two first cylinders 23 are symmetrically distributed at the upper and lower sides of the rear of the frame 1 and the two first cylinders 23 are fixedly connected to the frame 1; the telescopic end of the first cylinder 23 is fixedly connected to the sliding frame 5; During operation, the two first cylinders 23 can be activated to drive the sliding frame 5 to slide forward and backward on the frame 1.

[0022] like Figure 2-Figure 5 As shown, as a further solution of the present invention, the pushing mechanism includes a fixed frame 24, which is fixedly connected to the frame 1 and is relatively perpendicular to the frame 1; a sliding plate 25 is slidably connected in the fixed frame 24, and three pushing grooves 26 are provided on the sliding plate 25; a second cylinder 27 is fixedly connected to the right position of the fixed frame 24, and the telescopic end of the second cylinder 27 is fixedly connected to the sliding plate 25; During operation, after the tube blank 2 completes the first diameter expansion, the second cylinder 27 is started to drive the sliding plate 25 to move to the left, and the sliding plate 25 will drive the larger pushing groove 26 in the middle to move to the rear position of the tube blank 2; when the larger mandrel 3 is inserted into the tube blank 2 and fixed on the frame 1, the tube blank 2 is driven to move backward, and the part of the tube blank 2 that needs to be expanded will pass through the larger pushing groove 26 in the middle; when the tube blank 2 is pulled forward, the tube blank 2 will complete a diameter expansion under the action of the larger mandrel 3 and the larger pushing groove 26 in the middle position.

[0023] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0024] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for the expansion and contraction drawing of a different-walled tube, comprising a frame (1), characterized in that: A tube blank (2) is arranged in the frame (1), a mandrel (3) is arranged inside the tube blank (2), the rear end of the mandrel (3) is fixedly connected to the frame (1), and a groove (4) is provided at the front end of the frame (1), the diameter of the groove (4) is larger than the inner diameter of the tube blank (2); a pushing mechanism is provided at the tube expansion position on the outer surface of the tube blank (2), the pushing mechanism is used to cooperate with multiple mandrels (3) to complete multiple tube expansion of the tube blank (2); a clamping mechanism is provided in the frame (1), the clamping mechanism is used to clamp the tube wall at the front end of the tube blank (2) without affecting the mandrel (3) from the front end of the tube blank (2) into the tube blank (2); a drawing mechanism is provided on the frame (1), the drawing mechanism is used to pull the tube blank (2) forward after the clamping mechanism clamps the tube blank (2).

2. The expansion and contraction drawing process of a different-wall tube according to claim 1, characterized in that: The clamping mechanism comprises a sliding frame (5), the sliding frame (5) is slidably connected to the frame (1) and four first clamping blocks (6) are arranged in the sliding frame (5); the four first clamping blocks (6) are distributed in the sliding frame (5) in a circular array, and the distance between two relative first clamping blocks (6) is greater than the outer diameter of the tube blank (2); the sliding frame (5) is provided with an adjustment mechanism, and the adjustment mechanism is used to simultaneously drive the four first clamping blocks (6) to move to a position close to the tube blank (2) or away from the tube blank (2); the first clamping block (6) is provided with a fastening mechanism, and the fastening mechanism is used to cooperate with the first clamping block (6) to clamp the tube wall of the tube blank (2).

3. The expansion and contraction drawing process of a different-wall tube according to claim 2, characterized in that: The adjustment mechanism comprises a bevel gear ring (7), the bevel gear ring (7) is sleeved on the sliding frame (5) and the bevel gear ring (7) is rotatably connected to the sliding frame (5); a handle (8) is fixedly connected to the bevel gear ring (7); a first threaded rod (9) is fixedly connected to the first clamping block (6), a sliding groove (10) is provided on the surface of the first threaded rod (9), and the sliding groove (10) on the first threaded rod (9) is slidably connected to the sliding frame (5); the first threaded rod (9) has a self-locking property and a first bevel gear (11) is threadedly connected to the first threaded rod (9), and the first bevel gear (11) is rotatably connected to the outer surface of the sliding frame (5); the bevel gear ring (7) is meshed with four first bevel gears (11) at the same time.

4. The expansion and contraction drawing process of a different-wall tube according to claim 2, characterized in that: The fastening mechanism comprises a second clamping block (12), the second clamping block (12) being rotatably connected to the first clamping block (6), and the distance between the second clamping block (12) and the first clamping block (6) being equal to the thickness of the tube wall of the tube blank (2); two positions of the second clamping block (12) connected to the first clamping block (6) are fixedly connected to a worm gear (13); two worm gears (14) are rotatably connected to the first clamping block (6), and the two worm gears (14) are respectively meshed with the two worm gears (13); and a driving mechanism is provided on the sliding frame (5), and the driving mechanism is used to simultaneously drive the four second clamping blocks (12) to rotate.

5. The expansion and contraction drawing process of a different-wall tube according to claim 4, characterized in that: The driving mechanism comprises a fixed frame (15), the fixed frame (15) being located inside the sliding frame (5) and fixedly connected to the sliding frame (5); an outer gear ring (16) being rotatably connected to the fixed frame (15); a second bevel gear (17) being fixedly connected to an end of the worm (14) away from the worm wheel (13); a third bevel gear (18) being meshed at a rear position of the second bevel gear (17); a first gear (19) being fixedly connected at a rear end of the third bevel gear (18); and the first gear (19) being meshed with the outer gear ring (16); and a rotating mechanism being provided on the sliding frame (5), the rotating mechanism being used to drive the outer gear ring (16) to rotate when the sliding frame (5) moves to a front position of the frame (1).

6. The expansion and contraction drawing process of a different-wall tube according to claim 5, characterized in that: The rotating mechanism comprises four second gears (20), the four second gears (20) are all rotatably connected to the fixing frame (15) and the four second gears (20) are all meshed with the outer gear ring (16); a second threaded rod (21) is fixedly connected to the front end of the second gear (20), the second threaded rod (21) is not self-locking and a threaded barrel (22) is provided in front of the second threaded rod (21), the threaded barrel (22) is threadedly connected to the second threaded rod (21) and the threaded barrel (22) is fixedly connected to the frame (1).

7. The expansion and contraction drawing process of a different-wall tube according to claim 2, characterized in that: The pulling mechanism comprises two first cylinders (23), the two first cylinders (23) being symmetrically distributed at upper and lower sides of the rear of the frame (1) and the two first cylinders (23) being fixedly connected to the frame (1); the telescopic ends of the first cylinders (23) are fixedly connected to the sliding frame (5).

8. The expansion and contraction drawing process of a different-wall tube according to claim 1, characterized in that: The pushing mechanism comprises a fixed frame (24), the fixed frame (24) being fixedly connected to the frame (1) and being relatively perpendicular to the frame (1); a sliding plate (25) being slidably connected inside the fixed frame (24), and three pushing grooves (26) being formed on the sliding plate (25); a second cylinder (27) being fixedly connected to the right side of the fixed frame (24), and a telescopic end of the second cylinder (27) being fixedly connected to the sliding plate (25).

Images