Multi-process shaping structure of stretcher

Abstract

The utility model discloses a multi-process reshaping structure of a stretcher, which comprises an upper die forming block, a lower die frame, an opening supporting block, a bottom supporting block, a first knockout block, a second knockout block, a movable sleeve, a pin pushing block, a reset piece, an upper ejector pin, a lower ejector pin, a material pushing block assembly and a main core rod, and the upper die forming block and the lower die frame are respectively provided with an upper reshaping groove and a lower reshaping groove. A gap exists between the bottom supporting block and the lower shaping groove. The opening supporting block is located on the upper portion of the main core rod, the first knockout block, the upper ejector pin, the pin pushing block, the reset piece, the second knockout block and the movable sleeve are arranged outside the main core rod in a sleeving mode, the upper die forming block pushes the second knockout block to move downwards, and the second knockout block drives the first knockout block to move downwards. The reset piece pushes the first knockout block to move upwards to reset, and the material pushing block assembly pushes the second knockout block to reset upwards. By means of the structure, multi-size shaping can be conducted on workpieces, step-by-step demolding is achieved through the reset piece and the material pushing block assembly, and the success rate and efficiency of workpiece shaping are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of kettle shaping, in particular to a multi-process shaping structure of a stretching machine. Background Art

[0002] In the process of producing kettles, it is necessary to stretch and shape the upper, lower, outer surface, etc. of the kettle in various sizes and angles. Therefore, after completing the shaping of one part of the kettle, it is necessary to transfer to the remaining shaping structures in sequence to carry out the shaping of the remaining positions. This results in a large number of equipment, high production costs, and a large amount of space occupied. A lot of manpower and material resources will be wasted during the shaping process, and the shaping efficiency is low, which needs to be improved. Summary of the Invention

[0003] The utility model aims to solve the defects in the prior art of requiring more equipment and having low shaping efficiency when shaping workpieces such as kettle bodies in multiple sizes and angles, and provides a new multi-process shaping structure of a stretching machine.

[0004] In order to solve the above technical problems, the present invention is implemented through the following technical solutions:

[0005] A multi-process shaping structure of a stretching machine includes an upper die forming block, a lower die frame, a mouth support block, a bottom support block, a first punching block, a second punching block, a movable sleeve, a push pin block, a reset member, an upper ejector pin, a lower ejector pin, a pusher block assembly and a main core rod. An upper shaping groove and a lower shaping groove are respectively formed on the upper die forming block and the lower die frame. The bottom support block is arranged in the lower shaping groove. The lower shaping groove is wide at the top and narrow at the bottom. There is a gap between the outer wall of the bottom support block and the inner wall of the lower shaping groove. The upper end of the lower ejector pin is movably inserted into the bottom support block, and the lower end of the lower ejector pin is in contact with the pusher block assembly.

[0006] The mouth support block is sleeved on the main core rod, the mouth support block is located on the upper part of the main core rod, the first punching block, the upper ejector pin, the push-pull block and the reset member are sleeved on the outside of the main core rod from top to bottom, the outer wall of the mouth support block is in contact with the inner wall of the first punching block, and the upper end of the mouth support block is located above the first punching block;

[0007] The lower end of the second punching block is in contact with the upper end of the movable sleeve, and the lower end of the movable sleeve is in contact with the upper end of the lower ejector pin. The second punching block and the movable sleeve are arranged outside the main core rod, the outer wall of the first punching block is in contact with the inner wall of the second punching block, the upper end of the first punching block is located above the second punching block, and the outer wall of the push pin is in contact with the inner wall of the movable sleeve;

[0008] The mouth support block, the first material block and the second material block are inserted into the upper shaping groove, the upper die forming block pushes the second material block to move downward, and the second material block drives the first material block to move downward; the reset member is arranged between the push pin and the bottom support block, and the reset member pushes the first material block, the push pin and the upper ejector pin to move upward and reset, and the push block assembly pushes the second material block and the movable sleeve to move upward and reset.

[0009] Because the mouth support block, the first material block and the second material block are distributed from inside to outside, and the upper ends of the mouth support block, the first material block and the second material block are at different heights, the shaping of the workpiece at positions A, B, C and D can be realized through the cooperation of the mouth support block, the first material block, the second material block and the upper shaping groove, the shaping of the workpiece at multiple angles and sizes at the lower part can be realized through the cooperation of the lower shaping groove and the gap, and the length of the middle part of the workpiece can also be shaped, thereby improving the efficiency of shaping multiple positions of the workpiece at multiple sizes and reducing the waste of materials; the first material block and the second material block can be step demolded through the reset member and the push block assembly, which not only prevents the workpiece from being clamped at position A and deformed at position B during demolding, but also facilitates the complete removal of the shaped workpiece, thereby improving the success rate of workpiece shaping.

[0010] As a preferred embodiment, the lower die frame comprises an upper circular table, a support column and a lower circular table distributed from top to bottom, the two ends of the support column are arranged on the upper circular table and the lower circular table respectively, and the lower shaping groove is arranged on the upper circular table; the push block assembly comprises a disc and a top rod arranged at the lower end of the disc, the disc is arranged between the upper circular table and the lower circular table, the disc is located on the inner side of the support column, the lower end of the top rod penetrates out of the lower circular table, and the top rod drives the disc to reciprocate in the direction of approaching or moving away from the lower circular table.

[0011] The top rod is arranged on the lower die frame, thereby improving the stability of the disc during movement and the stability of the lower ejector pin during upward movement and resetting; the lower circular table and the disc limit the downward movement distance of the second material block, thereby improving the accuracy of shaping the workpiece through the second material block, the upper shaping groove, the lower shaping groove and the first gap.

[0012] As a preferred embodiment, the second material block is provided with a plurality of penetrating holes, the penetrating holes are distributed in a circumferential direction, the number of the upper ejector pins is equal to the number of the penetrating holes, the upper end of the upper ejector pin penetrates out of the penetrating hole and abuts against the lower end of the first material block, and the lower end of the upper ejector pin abuts against the upper surface of the push pin.

[0013] Through the through hole and the upper ejector, the second punching block can move along the upper ejector, which improves the stability of the upper mold forming block pushing the second punching block to move downward; the upper ejector is circumferentially distributed outside the main core rod, which improves the balance and stability of pushing the first punching block and the pusher block to move.

[0014] Preferably, in the above-mentioned multi-process shaping structure of a stretching machine, the reset part includes a reset spring and a limit plate, the limit plate is arranged between the upper end of the reset spring and the lower end of the push push block, the lower end of the reset spring is abutted against the upper surface of the bottom support block, the upper end of the reset spring is abutted against the limit plate, and the reset spring pushes the limit plate tightly against the lower surface of the push push block.

[0015] The limit plate enables the reset spring to provide a balanced pushing force to the push-pull block, thereby improving the smoothness of the reset of the first punching block, the upper ejector pin and the push-pull block after the shaping is completed.

[0016] Preferably, in the above-mentioned multi-process shaping structure of a stretching machine, a sliding groove is provided on the pushing block, and a positioning ring is provided on the outer wall of the main core rod. The positioning ring is inserted into the sliding groove, and the first punching block pushes the pushing block downward to the top of the sliding groove and abuts against the upper surface of the positioning ring, and the reset member pushes the pushing block upward to the lower surface of the positioning ring and abuts against the upper surface of the limit plate.

[0017] The positioning ring and the sliding groove can limit the moving distance of the first punching block and the second punching block, further improving the accuracy of shaping multiple positions of the workpiece.

[0018] Preferably, in the above-mentioned multi-process shaping structure of a stretching machine, the main core rod includes an upper pressure plate and a lower rod, the upper pressure plate includes a first section and a second section distributed from top to bottom, the width of the first section is greater than the width of the second section, the upper surface of the lower rod is provided with a vertical groove, the second section is inserted into the vertical groove and plug-fitted; a first hole is passed through the upper pressure plate, a second hole is provided at the bottom of the vertical groove, and the first hole is opposite to the second hole; a plug-in groove is formed between the lower surface of the first section, the side wall of the second section and the upper surface of the lower rod, the inner side of the mouth support block is inserted into the plug-in groove and plug-fitted, and the outer side of the mouth support block passes through the plug-in groove.

[0019] The upper pressure plate is detachably arranged on the lower rod, which facilitates the assembly of the mouth support block in the plug-in slot, and the mouth support block is pressed and fixed by the cooperation of the upper pressure plate, the first hole, the second hole and the screw, which facilitates installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0021] Figure 2 This is a cross-sectional view showing the gap, the through hole, the sliding groove, and the plug-in groove of the present invention;

[0022] Figure 3 This is a schematic diagram of the explosion structure of the main core rod of the utility model;

[0023] Figure 4 This is a cross-sectional view of a workpiece to be shaped according to the present invention;

[0024] Figure 5 This is a cross-sectional view of the upper mold forming block, the first punching block, and the second punching block of the utility model being separated;

[0025] Figure 6 This is a cross-sectional view of the contact between the upper mold forming block and the second punching block of the utility model;

[0026] Figure 7 This is a cross-sectional view of the upper mold forming block of the utility model pushing the second punching block and driving the first punching block to move downward;

[0027] Figure 8 This is a cross-sectional view of the upper mold forming block of the utility model pushing the second punching block downward to move into position;

[0028] Figure 9 This is a cross-sectional view of the reset member of the utility model pushing the first punching block, the upper ejector pin and the push pin block to reset upward.

[0029] Explanation of the accompanying drawings: 1. Upper mold forming block; 11. Upper shaping groove; 2. Lower mold frame; 21. Lower shaping groove; 22. Upper round table; 23. Support column; 24. Lower round table; 3. Mouth support block; 300, gap; 31. Bottom support block; 4. First punching block; 41. Second punching block; 411. Through hole; 5. Movable sleeve; 51. Pushing block; 511. Sliding groove; 6. Resetting member; 61. Resetting spring; 62. Limiting plate; 7. Upper ejector pin; 71. Lower ejector pin; 8. Pushing block assembly; 81. Disc; 82. Ejector rod; 9. Main core rod; 91. Positioning ring; 92. Upper pressure plate; 921. First section; 922. Second section; 923. First hole; 93. Lower rod; 931. Vertical groove; 932. Second hole; 94. Connecting groove. DETAILED DESCRIPTION

[0030] The following is combined with Figures 1-9 The present invention is further described in detail with reference to the following specific embodiments, but they are not intended to limit the present invention:

[0031] Example 1

[0032] like Figures 1-9As shown, a multi-process shaping structure of a stretching machine includes an upper mold forming block 1, a lower mold frame 2, a mouth support block 3, a bottom support block 31, a first punching block 4, a second punching block 41, a movable sleeve 5, a push pin 51, a reset member 6, an upper ejector pin 7, a lower ejector pin 71, a pusher block assembly 8 and a main core rod 9. The upper mold forming block 1 and the lower mold frame 2 are respectively provided with an upper shaping groove 11 and a lower shaping groove 21. The bottom support block 31 is arranged in the lower shaping groove 21. The lower shaping groove 21 is arranged to be wide at the top and narrow at the bottom. There is a gap 300 between the outer wall of the bottom support block 31 and the inner wall of the lower shaping groove 21. The upper end of the lower ejector pin 71 is movably inserted into the bottom support block 31, and the lower end of the lower ejector pin 71 is in contact with the pusher block assembly 8.

[0033] The mouth support block 3 is sleeved on the main core rod 9. The mouth support block 3 is located on the upper part of the main core rod 9. The first punching block 4, the upper ejector pin 7, the push-pull block 51 and the reset member 6 are sleeved on the outside of the main core rod 9 from top to bottom. The outer wall of the mouth support block 3 is in contact with the inner wall of the first punching block 4. The upper end of the mouth support block 3 is located above the first punching block 4.

[0034] The lower end of the second punching block 41 is in contact with the upper end of the movable sleeve 5, and the lower end of the movable sleeve 5 is in contact with the upper end of the lower ejector pin 71. The second punching block 41 and the movable sleeve 5 are sleeved on the outside of the main core rod 9. The outer wall of the first punching block 4 is in contact with the inner wall of the second punching block 41. The upper end of the first punching block 4 is located above the second punching block 41. The outer wall of the push-pull block 51 is in contact with the inner wall of the movable sleeve 5.

[0035] The mouth support block 3, the first punching block 4 and the second punching block 41 are inserted into the upper shaping groove 11, the upper mold forming block 1 pushes the second punching block 41 to move downward, and the second punching block 41 drives the first punching block 4 to move downward; the reset member 6 is arranged between the push-pull block 51 and the bottom support block 31, and the reset member 6 pushes the first punching block 4, the push-pull block 51 and the upper ejector 7 to move upward and reset, and the pushing block assembly 8 pushes the second punching block 41 and the movable sleeve 5 to reset upward.

[0036] Preferably, the lower mold frame 2 includes an upper cone 22, a support column 23 and a lower cone 24 distributed from top to bottom, the two ends of the support column 23 are respectively arranged on the upper cone 22 and the lower cone 24, and the lower shaping groove 21 is arranged on the upper cone 22; the pushing block assembly 8 includes a disc 81 and a push rod 82 arranged at the lower end of the disc 81, the disc 81 is arranged between the upper cone 22 and the lower cone 24, the disc 81 is located on the inner side of the support column 23, the lower end of the push rod 82 passes through the lower cone 24, and the push rod 82 drives the disc 81 to move back and forth toward or away from the lower cone 24.

[0037] Preferably, a plurality of through holes 411 are provided on the second punching block 41, and the through holes 411 are distributed circumferentially. The number of the upper ejector pins 7 is multiple and corresponds one-to-one to the through holes 411. The upper ends of the upper ejector pins 7 pass through the through holes 411 and abut against the lower ends of the first punching block 4, and the lower ends of the upper ejector pins 7 abut against the upper surface of the push pin block 51.

[0038] Preferably, the reset member 6 includes a reset spring 61 and a limit plate 62, and the limit plate 62 is arranged between the upper end of the reset spring 61 and the lower end of the push-pull block 51. The lower end of the reset spring 61 is against the upper surface of the bottom support block 31, and the upper end of the reset spring 61 is against the limit plate 62. The reset spring 61 pushes the limit plate 62 to press against the lower surface of the push-pull block 51.

[0039] Preferably, a sliding groove 511 is provided on the pushing block 51, and a positioning ring 91 is provided on the outer wall of the main core rod 9. The positioning ring 91 is inserted into the sliding groove 511. The first punching block 4 pushes the pushing block 51 to move downward to the top of the sliding groove 511 and abut against the upper surface of the positioning ring 91. The reset member 6 pushes the pushing block 51 to move upward to the lower surface of the positioning ring 91 and abut against the upper surface of the limit plate 62.

[0040] Preferably, the main core rod 9 includes an upper pressure plate 92 and a lower rod 93, and the upper pressure plate 92 includes a first section 921 and a second section 922 distributed from top to bottom, the width of the first section 921 is greater than the width of the second section 922, and a vertical groove 931 is provided on the upper surface of the lower rod 93, and the second section 922 is inserted into the vertical groove 931 and plugged in; a first hole 923 is passed through the upper pressure plate 92, and a second hole 932 is provided at the bottom of the vertical groove 931, and the first hole 923 is directly opposite to the second hole 932; a plug-in groove 94 is formed between the lower surface of the first section 921, the side wall of the second section 922 and the upper surface of the lower rod 93, and the inner side of the mouth support block 3 is inserted into the plug-in groove 94 and plug-in fit, and the outer side of the mouth support block 3 passes through the plug-in groove 94.

[0041] Specifically, in the embodiment of the present application, the upper parts of the first beating block 4 and the second beating block 4 are both integrally formed with inclined portions, and the lower ends of the inclined portions are gradually inclined outward along the height direction.

[0042] The upper mold frame also includes an upper mold block 1 fixed at its lower end, which drives the upper mold block 1 to move toward or away from the lower mold frame 2. The upper shaping groove 11 includes an upper zone, an upper zone 2, and an upper zone 3, which are arranged from top to bottom. The width of the upper zone is smaller than that of the upper zone 2, and the width of the upper zone 2 is smaller than that of the upper zone 3.

[0043] The upper die forming block 1 pushes the second punching block 41 downward through the upper three areas, and the upper die forming block 1 pushes the first punching block 4 downward through the upper two areas. The upper shaping groove 11 cooperates with the mouth support block 3, the first punching block 4 and the second punching block 41 to perform multi-size shaping on A, B, C and D on the upper part of the workpiece.

[0044] The lower shaping groove 21 includes a lower zone, a lower second zone and a lower third zone distributed from top to bottom. The width of the lower zone is greater than the width of the lower second zone, and the width of the lower second zone is greater than the width of the lower third zone. A gap 300 is formed between the lower part of the lower second zone, the lower third zone and the bottom support block 31, thereby allowing multi-size shaping to be performed at E, F, G and H of the lower part of the workpiece, thereby improving the efficiency of shaping of different sizes at multiple positions on the workpiece, reducing material waste and facilitating use.

[0045] More specifically, when performing shaping operations on a workpiece, such as Figures 4-9 , can go through four steps.

[0046] The first step, such as Figure 5 As shown, the upper mold forming block 1 is away from the lower mold frame 2, and the upper end of the lower ejector pin 71 passes through the upper end of the lower mold frame 2. At this time, the workpiece to be shaped is placed on the second punching block 41.

[0047] The second step is Figure 4 、 Figure 6 、 Figure 7 As shown, the upper die frame drives the upper die forming block 1 to move toward the second punching block 41. When the top of the upper three zones is in contact with the surface at position D on the upper part of the workpiece, as the upper die forming block 1 moves further, the upper die forming block 1 pushes the second punching block 41, the movable sleeve 5, the lower ejector pin 71, and the pusher block assembly 8 downward. At this time, position D can be clamped and shaped by the upper three zones and the second punching block 41.

[0048] Because the side wall of the second punching block 41 is in contact with the outer wall of the first punching block 4, the second punching block 41 can drive the first punching block 4 to move downward, and then drive the upper ejector pin 7 and the push push block 51 to move downward. The reset part 6 is compressed, and the workpiece moves downward with the first punching block 4 and the second punching block 41. The lower part of the workpiece is inserted into the lower two areas, and the inner surface of C is in contact with the outer surface of the first punching block 4, so that the height difference between the first punching block 4 and the second punching block 41 can be used to shape the connection position between C and D to a suitable angle.

[0049] The third step, such as Figure 4 、 Figure 8As shown, the upper die forming block 1 continues to push the first punching block 4 and the second punching block 41 downward. When the upper surface of the positioning ring 91 abuts the top of the sliding groove 511 and the lower surface of the disc 81 abuts the upper surface of the lower truncated cone 24, the upper die forming block 1 moves downward into position. At this point, the upper end of the first punching block 4 abuts the inner surface of point B, and the inner surface of point A abuts the outer surface of the mouth support block 3, thereby shaping the workpiece at points A and B.

[0050] As the workpiece moves downward, the lower part of the workpiece is inserted into the gap 300, the inner surface of the next zone is in contact with the outer surface at E, the inner surface of the lower two zones is in contact with the outer surface at F, and the inner surface of the gap 300 is in contact with G and H. Therefore, the lower part of the workpiece can be shaped to multiple sizes through the mutual cooperation between the lower shaping groove 21 and the gap 300.

[0051] The fourth step is as follows Figure 4 、 Figure 5 and Figure 9 As shown, when the shaping is completed, the upper mold frame drives the upper mold forming block 1 to move upward and reset. At this time, the reset spring 61 pushes the limit plate 62, the push-pull block 51, the upper ejector pin 7, and the first punching block 4 to move upward and reset. The workpiece resets upward with the first punching block 4, so that A is separated from the mouth support block 3, D is separated from the second punching block 41, and E and F are completely withdrawn from the lower shaping groove 21; then the ejector pin 82 pushes the disc 81, the lower ejector pin 71, the movable sleeve 5, and the second punching block 41 to move upward and reset. The second punching block 41 pushes the workpiece further upward through D, so that A, B, and C are separated from the mouth support block 3 and the first punching block 4, so that G and F can be completely withdrawn from the lower shaping groove 21, thereby releasing the clamping fixation of the workpiece, facilitating the removal of the workpiece after the shaping is completed, and completing the shaping of the workpiece. In addition to the above steps, users can increase or decrease the order of the above steps according to actual needs.

[0052] During demoulding, the first punching block 4 is first pushed upward by the reset member 6, thereby preventing the situation that jamming occurs at A and deformation occurs at B during demoulding; the second punching block 41 is pushed upward and reset by the lower ejector pin 71 and the pusher block assembly 8, and the upper end of the second punching block 41 can drive the workpiece to move upward smoothly through the plane where D is located, thereby improving the smoothness and success rate of demoulding.

[0053] In short, the above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made within the scope of the patent application for the present invention should fall within the scope of the present invention.

Claims

1. A stretching machine multi-step shaping structure, characterized by: The invention comprises an upper die forming block (1), a lower die frame (2), a mouth support block (3), a bottom support block (31), a first punching block (4), a second punching block (41), a movable sleeve (5), a push pin block (51), a reset member (6), an upper ejector pin (7), a lower ejector pin (71), a pusher block assembly (8) and a main core rod (9); an upper shaping groove (11) and a lower shaping groove (21) are respectively provided on the upper die forming block (1) and the lower die frame (2); the bottom support block (31) is arranged in the lower shaping groove (21); the lower shaping groove (21) is arranged to be wide at the top and narrow at the bottom; a gap (300) exists between the outer wall of the bottom support block (31) and the inner wall of the lower shaping groove (21); the upper end of the lower ejector pin (71) is movably inserted into the bottom support block (31); and the lower end of the lower ejector pin (71) is in contact with the pusher block assembly (8); The mouth support block (3) is sleeved on the main core rod (9), and the mouth support block (3) is located on the upper part of the main core rod (9). The first punching block (4), the upper ejector pin (7), the push-pull block (51) and the reset member (6) are sleeved on the outside of the main core rod (9) from top to bottom. The outer wall of the mouth support block (3) is in contact with the inner wall of the first punching block (4), and the upper end of the mouth support block (3) is located above the first punching block (4). The lower end of the second punching block (41) is in contact with the upper end of the movable sleeve (5), and the lower end of the movable sleeve (5) is in contact with the upper end of the lower ejector pin (71). The second punching block (41) and the movable sleeve (5) are sleeved on the outside of the main core rod (9). The outer wall of the first punching block (4) is in contact with the inner wall of the second punching block (41). The upper end of the first punching block (4) is located above the second punching block (41). The outer wall of the push-pull block (51) is in contact with the inner wall of the movable sleeve (5). The mouth support block (3), the first punching block (4) and the second punching block (41) are inserted into the upper shaping groove (11); the upper mold forming block (1) pushes the second punching block (41) to move downward, and the second punching block (41) drives the first punching block (4) to move downward; the reset member (6) is arranged between the push-pull block (51) and the bottom support block (31); the reset member (6) pushes the first punching block (4), the push-pull block (51) and the upper ejector pin (7) to move upward and reset, and the push-pull block assembly (8) pushes the second punching block (41) and the movable sleeve (5) to reset upward.

2. The multi-step shaping structure of a stretching machine according to claim 1, characterized in that: The lower mold frame (2) includes an upper truncated cone (22), a support column (23) and a lower truncated cone (24) distributed from top to bottom, the two ends of the support column (23) are respectively arranged on the upper truncated cone (22) and the lower truncated cone (24), and the lower shaping groove (21) is arranged on the upper truncated cone (22); the pushing block assembly (8) includes a disc (81) and a push rod (82) arranged at the lower end of the disc (81), the disc (81) is arranged between the upper truncated cone (22) and the lower truncated cone (24), the disc (81) is located on the inner side of the support column (23), the lower end of the push rod (82) passes through the lower truncated cone (24), and the push rod (82) drives the disc (81) to move back and forth in a direction close to or away from the lower truncated cone (24).

3. The multi-step shaping structure of a stretching machine according to claim 1, characterized in that: The second punching block (41) is provided with a plurality of through holes (411), and the through holes (411) are distributed in a circumferential direction. The number of the upper ejector pins (7) is set in a plurality and corresponds one to one with the through holes (411). The upper ends of the upper ejector pins (7) pass through the through holes (411) and abut against the lower ends of the first punching block (4), and the lower ends of the upper ejector pins (7) abut against the upper surface of the push pin block (51).

4. The multi-step shaping structure of a stretching machine according to claim 1, characterized in that: The reset member (6) includes a reset spring (61) and a limit plate (62). The limit plate (62) is arranged between the upper end of the reset spring (61) and the lower end of the push-pull block (51). The lower end of the reset spring (61) abuts against the upper surface of the bottom support block (31). The upper end of the reset spring (61) abuts against the limit plate (62). The reset spring (61) pushes the limit plate (62) to press against the lower surface of the push-pull block (51).

5. The multi-step shaping structure of a stretching machine according to claim 4, characterized in that: A sliding groove (511) is provided on the push-pull block (51), and a positioning ring (91) is provided on the outer wall of the main core rod (9). The positioning ring (91) is inserted into the sliding groove (511). The first punching block (4) pushes the push-pull block (51) to move downward to the top of the sliding groove (511) and abut against the upper surface of the positioning ring (91). The reset member (6) pushes the push-pull block (51) to move upward to the lower surface of the positioning ring (91) and abut against the upper surface of the limit plate (62).

6. The multi-step shaping structure of a stretching machine according to claim 1, characterized in that: The main core rod (9) includes an upper pressing plate (92) and a lower rod (93), the upper pressing plate (92) includes a first section (921) and a second section (922) distributed from top to bottom, the width of the first section (921) is greater than the width of the second section (922), the upper surface of the lower rod (93) is provided with a vertical groove (931), the second section (922) is inserted into the vertical groove (931) and plugged in; the upper pressing plate (92) is provided with a first hole (923), a second hole (932) is provided at the bottom of the vertical slot (931), and the first hole (923) is directly opposite to the second hole (932); a plug-in groove (94) is formed between the lower surface of the first section (921), the side wall of the second section (922) and the upper surface of the lower rod (93), the inner side of the mouth support block (3) is inserted into the plug-in groove (94) and plug-fitted, and the outer side of the mouth support block (3) passes through the plug-in groove (94).

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