A stretch-die necking machine

Abstract

The present application relates to the technical field of pipeline processing, and particularly relates to a pipe expanding and necking machine. The pipe expanding and necking machine comprises a rack, a supporting mechanism and a clamping mechanism are arranged on the rack, an expanding and necking mechanism is arranged on the clamping mechanism, and the clamping mechanism is composed of a transverse adjusting mechanism, a rotating mechanism and an expanding mechanism. The present application can effectively protect the appearance and structural integrity of the processed pipeline by uniformly applying force to the inner side of the pipeline through internal radial flexible clamping technology. The adjustable expanding die can quickly adapt to different pipe diameters and wall thicknesses without the need for overall replacement, greatly shortening the changeover time, significantly improving the production flexibility of the equipment, and realizing automatic operation from positioning, clamping, processing to unloading through automatic integration of the equipment. The connection between processes is smooth, manual intervention and process conversion time are greatly reduced, and production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of pipe processing technology, and in particular to a mold expansion and shrinking machine. Background Technology

[0002] During the pipe manufacturing process, in order to facilitate the installation of adjacent pipe sections, it is necessary to flare or reduce the ends of the pipes. Currently, flare or reduce pipe ends are mainly performed using flare or reduce machines.

[0003] For example, Chinese invention patent CN110355291A discloses a steel pipe expansion and contraction device and a method for expanding and contracting steel pipes. The steel pipe expansion and contraction device includes a frame, a feeding device, a clamping device, and an expansion and contraction device. The clamping device and the expansion and contraction device are mounted on the frame. The feeding device is connected to the clamping device. The feeding device is used to feed the steel pipe to be processed and to deliver the steel pipe that has completed the expansion and contraction operation from the clamping device. The clamping device is used to clamp and fix the steel pipe to be processed from the feeding device. The expansion and contraction device performs the expansion and contraction operation on the steel pipe on the clamping device. Although the above-mentioned prior art has a safe and controllable feeding process through the feeding device, and the speed can be freely adjusted, thereby improving efficiency, and prevents the steel pipe from moving through the clamping device, facilitating subsequent processing of the steel pipe, the expansion and contraction device... The necking device performs necking and expansion operations on steel pipes, enabling automatic loading and unloading of steel pipes. The necking and expansion operation is convenient and efficient. However, with the expansion of new materials, more and more workpieces are being made of plastics, composite materials, or thin-walled metals. When the above-mentioned external clamping method is applied to such workpieces, the clamping force of the external clamping is concentrated on a local area of ​​the outer wall of the workpiece. For plastic cylinders with poor rigidity or metal cylinders with very thin walls, this localized stress concentration can easily cause irreversible indentation or elliptical deformation of the workpiece during the clamping stage, which seriously affects the quality of the finished product. Moreover, when the cross-section of the workpiece is non-circular or has slight irregularities, traditional external clamping is difficult to guarantee uniform clamping force and centering. Fixed stamping dies are also difficult to adapt to its shape changes, which can easily lead to uneven forming.

[0004] Therefore, it is necessary to design a mold expansion and shrinkage machine. Summary of the Invention

[0005] In order to overcome the shortcomings of existing expansion and shrinking machines that use external clamping, which are prone to deformation due to stress concentration when processing plastic and thin-walled workpieces, and are difficult to adapt to non-circular or irregular cross-sections, thus affecting the quality of finished products, this invention provides an expansion and shrinking machine.

[0006] The technical implementation of the present invention is as follows: a mold expansion and shrinking machine includes a frame, a supporting mechanism and a clamping mechanism on the frame, and an expansion and shrinking mechanism on the clamping mechanism. The clamping mechanism is composed of a lateral adjustment mechanism, a rotation mechanism and an expansion mechanism.

[0007] As a further preferred embodiment, the supporting mechanism includes a first slide rail, a first slider, a first motor, a first screw, and a clamping block. Two symmetrically distributed first slide rails are fixedly provided on the rear side of the frame. The first slider is slidably connected to the first slide rail. A clamping block is fixed between the rear sides of the two first sliders. The first motor is installed on the rear side of the frame. The first screw is connected to the output shaft of the first motor. The clamping block is threadedly connected to the first screw.

[0008] As a further preferred embodiment, the lateral adjustment mechanism includes a second slide rail, a second slider, a support block, a second motor, and a second screw. Two second slide rails are fixedly installed on the left and right sides of the top of the frame and are symmetrically distributed front and back. The second slider is slidably connected to the second slide rail. The support block is fixed between the tops of the second sliders on the same side. The second motor is installed on the top of the frame. The second screw is connected to the output shaft of the second motor. The support block is threadedly connected to the second screw.

[0009] As a further preferred embodiment, the rotating mechanism includes a connecting frame, a fixed disk, a third motor, a first gear, a second gear, and a chain. The connecting frame is rotatably connected inside the support block, and the fixed disk is fixedly installed on the left side of the connecting frame. The third motor is installed on the top of the support block, and the first gear is connected to the output shaft of the third motor. The second gear is fixedly installed outside the connecting frame, and the power is transmitted between the first gear and the second gear through a chain.

[0010] As a further preferred embodiment, the expansion mechanism includes a first electric push rod, a connecting rod, a top block, a third slide rail, and a contact block. The first electric push rod is installed on one side of the two support blocks facing away from each other. The first electric push rod is connected to a connecting rod via a telescopic rod. The connecting rod is located inside the connecting frame and is slidably connected to it. The left side of the connecting rod passes through the connecting frame and is fixedly provided with a top block. Several third slide rails are fixedly provided inside the fixed plate. Contact blocks are slidably connected to the third slide rails. An elastic element is provided between the contact block and the third slide rail above it. The top block contacts the contact block on the same side.

[0011] As a further preferred embodiment, the expansion and contraction mechanism includes a support frame, a fourth motor, a third screw, an upper sealing knife, a fourth slide rail, a fifth motor, a fourth screw, a lower sealing knife, and a fifth slide rail. A support frame is fixedly mounted on the top of the support block, and a fourth motor is mounted on the top of the support frame. A third screw is connected to the output shaft of the fourth motor, and an upper sealing knife is threaded onto the external part of the third screw. A fourth slide rail is fixedly mounted inside the top of the support frame, and the upper sealing knife is slidably connected to the fourth slide rail. A fifth motor is mounted on the top of the support frame, and a fourth screw is connected to the output shaft of the fifth motor. A lower sealing knife is threaded onto the external part of the fourth screw. Heating tubes are embedded inside the upper and lower sealing knives. A fifth slide rail is fixedly mounted inside the top of the support frame, and the lower sealing knife is slidably connected to the fifth slide rail.

[0012] As a further preferred option, a second electric push rod is installed on the front and rear sides of the bottom of the support frame, and a protective plate is connected to the telescopic rod of the second electric push rod.

[0013] As a further preferred embodiment, a first buffer pad is fixedly provided on the top of the clamping block, and a magnet is fixedly provided on the inner side of the first buffer pad.

[0014] As a further preferred option, a protective frame is fixedly provided on the opposite side of the two support blocks, and the first gear, the second gear and the chain are located inside the protective frame.

[0015] As a further preferred option, a second buffer pad is fixedly provided on the outside of the contact block.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: 1. By adopting internal radial flexible clamping technology, force is applied evenly from the inside of the pipe, effectively protecting the appearance and structural integrity of the pipe. The adjustable expansion mold can quickly adapt to different pipe diameters and wall thicknesses without the need for overall replacement, greatly shortening the changeover time and significantly improving the production flexibility of the equipment. The automated integration of the equipment realizes fully automated operation from positioning, clamping, processing to unloading. The connection between each process is smooth, greatly reducing manual intervention and process changeover time, and improving production efficiency.

[0017] 2. This invention achieves precise adjustment of the support height through a first motor and a first screw. The screw can be removed during processing to avoid interference, and can automatically reset to support the workpiece after processing, ensuring a stable and safe part removal process. At the same time, the lateral adjustment mechanism driven by the second motor can achieve precise centering and axial positioning of the clamping mechanism on the pipe port, providing a reliable reference positioning for subsequent heat sealing operations, and ensuring the consistency of the sealing position and processing accuracy from the source.

[0018] 3. This invention, by setting a first buffer pad, a magnet, and a second buffer pad, can prevent hard contact from scratching the pipe surface and also play a role in anti-slip buffering. The magnet can magnetically attract and fix the bottom of the pipe, effectively preventing loosening, slippage, and displacement during pipe processing, improving the stability of material placement, and providing a stable positioning foundation for subsequent processing. The second buffer pad provides a flexible clamping force, which can firmly grasp the material while avoiding scratching the inner wall of the pipe. It is particularly suitable for easily deformable workpieces such as plastics, composite materials, or thin-walled metals. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0020] Figure 2 This is a three-dimensional structural diagram of the first slide rail, the first motor, and the protective frame of the present invention.

[0021] Figure 3 This is a three-dimensional structural diagram of the clamping block, the first buffer pad, and the magnet of the present invention.

[0022] Figure 4 This is a three-dimensional structural diagram of the second slider, support block, and second motor components of the present invention.

[0023] Figure 5 This is a three-dimensional structural diagram of the connecting frame, fixing plate, and third motor of the present invention.

[0024] Figure 6 This is a three-dimensional structural diagram of the components of the present invention, including the first electric push rod, the top block, and the third slide rail.

[0025] Figure 7 This is a three-dimensional structural masked view of the connecting rod, top block, and third slide rail components of the present invention.

[0026] Figure 8 This is a three-dimensional structural diagram of the first gear, the second gear, and the chain component of the present invention.

[0027] Figure 9 This is a three-dimensional structural diagram of the support frame, fourth motor, and upper sealing knife of the present invention.

[0028] Figure 10 This is an exploded three-dimensional view of the components of the present invention, including the fifth motor, the fourth screw, and the lower sealing knife.

[0029] Figure 11 This is a three-dimensional structural diagram of the second electric push rod and protective plate component of the present invention.

[0030] The components in the attached diagram are labeled as follows: 1. Frame; 2. Supporting mechanism; 21. First slide rail; 22. First slider; 23. First motor; 24. First screw; 25. Clamping block; 26. First buffer pad; 27. Magnet; 3. Clamping mechanism; 31. Lateral adjustment mechanism; 311. Second slide rail; 312. Second slider; 313. Support block; 314. Second motor; 315. Second screw; 32. Rotating mechanism; 321. Connecting frame; 322. Fixed plate; 323. Third motor; 324. First... 325. Gear, 326. Second gear, 327. Chain, 328. Protective frame, 33. Expansion mechanism, 331. First electric push rod, 332. Connecting rod, 333. Top block, 334. Third slide rail, 335. Contact block, 336. Second buffer pad, 4. Expansion / contraction mechanism, 41. Support frame, 42. Fourth motor, 43. Third screw, 44. Upper sealing knife, 45. Fourth slide rail, 46. Fifth motor, 47. Fourth screw, 48. Lower sealing knife, 49. Fifth slide rail, 5. Second electric push rod, 6. Protective plate. Detailed Implementation

[0031] Example 1 A type of expansion and shrinking machine, such as Figure 1 , Figure 2 , Figure 4 , Figure 5 and Figure 9 As shown, it includes a frame 1, a support mechanism 2 and a clamping mechanism 3 on the frame 1, and an expansion and contraction mechanism 4 on the clamping mechanism 3. The clamping mechanism 3 is composed of a lateral adjustment mechanism 31, a rotation mechanism 32 and an expansion mechanism 33.

[0032] like Figure 2 and Figure 3 As shown, the supporting mechanism 2 includes a first slide rail 21, a first slider 22, a first motor 23, a first screw 24, and a clamping block 25. Two symmetrically distributed first slide rails 21 are welded to the rear side of the frame 1. The first slider 22 is slidably connected to the first slide rail 21 through a slide groove. The clamping block 25 is welded between the rear sides of the two first sliders 22. The first motor 23 is installed on the rear side of the frame 1. The first screw 24 is connected to the output shaft of the first motor 23. The clamping block 25 is threadedly connected to the first screw 24.

[0033] like Figure 4 As shown, the lateral adjustment mechanism 31 includes a second slide rail 311, a second slider 312, a support block 313, a second motor 314, and a second screw 315. Two second slide rails 311 are welded to the left and right sides of the top of the frame 1 and are symmetrically distributed front and back. The second slider 312 is slidably connected to the second slide rail 311 through a slide groove. The support block 313 is welded between the tops of the second sliders 312 on the same side. The second motor 314 is installed on the top of the frame 1. The second screw 315 is connected to the output shaft of the second motor 314. The support block 313 is threadedly connected to the second screw 315.

[0034] like Figure 5 , Figure 6 and Figure 8 As shown, the rotating mechanism 32 includes a connecting frame 321, a fixed disk 322, a third motor 323, a first gear 324, a second gear 325, and a chain 326. The connecting frame 321 is rotatably connected to the inside of the support block 313 via bearings. The fixed disk 322 is welded to the left side of the connecting frame 321. The third motor 323 is mounted on the top of the support block 313. The first gear 324 is connected to the output shaft of the third motor 323. The second gear 325 is welded to the outside of the connecting frame 321. Power is transmitted between the first gear 324 and the second gear 325 via the chain 326.

[0035] like Figure 5 , Figure 6 and Figure 7As shown, the expansion mechanism 33 includes a first electric push rod 331, a connecting rod 332, a top block 333, a third slide rail 334, and a contact block 335. The first electric push rod 331 is installed on one side of the two support blocks 313 facing away from each other. The first electric push rod 331 is connected to the telescopic rod of the first electric push rod 331 by the connecting rod 332. The connecting rod 332 is located inside the connecting frame 321 and is slidably connected to it through a slide groove. The left side of the connecting rod 332 passes through the connecting frame 321 and is welded to the top block 333. The top block 333 has a frustum structure. Four third slide rails 334 distributed circumferentially are welded to the inner side of the fixed plate 322. The contact blocks 335 are slidably connected to the third slide rails 334 through slide grooves. An elastic element, which is a spring, is provided between the contact block 335 and the third slide rail 334 above it. The top block 333 is in contact with the contact block 335 on the same side.

[0036] like Figure 9 and Figure 10 As shown, the expansion and contraction mechanism 4 includes a support frame 41, a fourth motor 42, a third screw 43, an upper sealing knife 44, a fourth slide rail 45, a fifth motor 46, a fourth screw 47, a lower sealing knife 48, and a fifth slide rail 49. The support frame 41 is welded to the top of the support block 313. The fourth motor 42 is mounted on the top of the support frame 41. The third screw 43 is connected to the output shaft of the fourth motor 42. The upper sealing knife 44 is externally threaded to the third screw 43. The fourth slide rail 45 is welded to the top of the inner part of the support frame 41. The upper sealing knife 44 is slidably connected to the fourth slide rail 45. The fifth motor 46 is mounted on the top of the support frame 41. The fourth screw 47 is connected to the output shaft of the fifth motor 46. The lower sealing knife 48 is externally threaded to the fourth screw 47. Heating tubes are embedded inside the upper sealing knife 44 and the lower sealing knife 48. The fifth slide rail 49 is welded to the top of the inner part of the support frame 41. The lower sealing knife 48 is slidably connected to the fifth slide rail 49 through a sliding groove.

[0037] This equipment is controlled by an integrated controller. The first motor 23, the second motor 314, the third motor 323, the first electric push rod 331, the fourth motor 42, the fifth motor 46, and the heating tube are all electrically connected to the controller, which is a Siemens S7-1200 model. When the device is to be used, the operator first places the cylindrical pipe to be processed horizontally on the clamping block 25. Then, according to the position to be processed at the pipe end, the operator starts the first motor 23 through the controller. The output shaft of the first motor 23 rotates, driving the first screw 24 to rotate, thereby driving the clamping block 25 and the first slider 22 to rise vertically along the first slide rail 21, adjusting the pipe end to the processing height corresponding to the subsequent expansion and contraction mechanism 4. After adjustment, the first motor 23 is turned off.

[0038] Subsequently, based on the pipe length, the controller starts the second motor 314. The output shaft of the second motor 314 rotates, driving the second screw 315 to rotate, which in turn drives the left and right support blocks 313 to move synchronously towards each other along the second slide rail 311 until the contact blocks 335 on both sides move to the vicinity of the inner side of the pipe port. Then, the controller shuts off the second motor 314 and starts the first electric push rod 331. The telescopic rod of the first electric push rod 331 extends and pushes the connecting rod 332 and the top block 333 to move towards the pipe. The conical surface of the top block 333 presses against the inclined surface on the inner side of each contact block 335, converting the linear thrust of the top block 333 into the radial outward movement of the contact blocks 335 along the third slide rail 334. Multiple contact blocks 335 expand outward synchronously, thereby tightening and fixing the pipe port from the inside. After the clamping is secure, the first electric push rod 331 is shut off.

[0039] At this time, the pipe is radially tightened and fixed by the internal contact block 335, and the lower clamping block 25 still plays an auxiliary supporting role. After confirming that the lateral clamping is firm, the first motor 23 is restarted to reverse it, driving the clamping block 25 to descend along the first slide rail 21, detaching from the support of the pipe and freeing up the processing space. After the clamping block 25 is reset, the controller shuts off the first motor 23 and starts the third motor 323. The output shaft of the third motor 323 rotates to drive the first gear 324 to rotate. Since the first gear 324 forms a transmission structure with the second gear 325 outside the connecting frame 321 through the chain 326, the chain 326 drives the second gear 325 and the connecting frame 321 to rotate at a uniform speed, so that the fixed plate 322 and the contact block 335 rotate synchronously, thereby driving the clamped pipe to rotate at a uniform speed around its own axis.

[0040] Then, the fifth motor 46 and the fourth motor 42 are started sequentially by the controller. The output shaft of the fifth motor 46 rotates to drive the fourth screw 47 to rotate, which drives the lower sealing knife 48 to rise smoothly along the fifth slide rail 49 and lightly touch the pipe port from below. The output shaft of the fourth motor 42 rotates to drive the third screw 43 to rotate, which drives the upper sealing knife 44 to move smoothly down along the fourth slide rail 45. The upper sealing knife 44 and the lower sealing knife 48 cooperate with each other. The built-in heating tube can evenly heat the pipe port when the upper sealing knife 44 and the lower sealing knife 48 contact the pipe. During the rotation of the pipe, the upper sealing knife 44 and the lower sealing knife 48 press the softened pipe port together to complete the shrinking and shaping operation.

[0041] After processing is completed, the controller controls the fourth motor 42 and the fifth motor 46 to reverse, driving the upper sealing knife 44 to move upward and the lower sealing knife 48 to move downward, so that it is detached from the workpiece. Then, the third motor 323 is turned off, and the pipe stops rotating. Next, the controller controls the first electric push rod 331 to retract, driving the top block 333 to move backward. Under the action of the elastic restoring force of the elastic element, each contact block 335 retracts radially along the third slide rail 334, releasing the clamping of the pipe port. Then, the output shaft of the first motor 23 is restarted to rotate forward, driving the clamping block 25 to move upward and support the processed pipe again. After supporting, the first motor 23 is turned off, and the second motor 314 is started, driving the two side support blocks 313 to move back and forth along the frame 1, so that the entire clamping mechanism 3 is withdrawn from the pipe port. After returning to the initial position, the second motor 314 is turned off, and the operator can then remove the processed pipe from the clamping block 25 to prepare for the next processing.

[0042] Example 2 like Figure 9 and Figure 11 As shown, based on Embodiment 1, Embodiment 2 further includes a second electric push rod 5 installed on the front and rear sides of the bottom of the support frame 41. The second electric push rod 5 is electrically connected to the controller, and a protective plate 6 is connected to the telescopic rod of the second electric push rod 5.

[0043] During the lateral movement of the support block 313, the second electric push rod 5 can be activated to push the protective plate 6 out to partially enclose the processing area, prevent accidental pipe displacement or external interference, and improve operational safety.

[0044] Example 3 like Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 7 As shown, based on Embodiment 2, Embodiment 3 further includes: a first buffer pad 26 is bonded to the top of the clamping block 25. The first buffer pad 26 is made of nylon, which is soft and can prevent hard contact from scratching the pipe surface, while also providing anti-slip properties. A magnet 27 is fixed to the inner side of the first buffer pad 26. A protective frame 327 is welded to the opposite side of the two support blocks 313. The first gear 324, the second gear 325, and the chain 326 are located inside the protective frame 327, effectively preventing debris from getting stuck inside the components, avoiding wear and safety hazards, and ensuring long-term stable operation of the transmission. A second buffer pad 336 is bonded to the outer side of the contact block 335. The second buffer pad 336 is made of rubber and can flexibly fit the inner wall of the pipe, preventing rigid support from causing pipe breakage.

Claims

1. A die expansion and contraction machine, comprising a frame (1), wherein a clamping mechanism (3) and a die expansion and contraction mechanism (4) are provided on the frame (1), the clamping mechanism (3) is used to clamp the pipe to be processed, and the die expansion and contraction mechanism (4) is mounted on the clamping mechanism (3) and located above and below the port of the clamped pipe, characterized in that, The frame (1) is also provided with a support mechanism (2) at the rear, which is used to support the pipe being processed; The clamping mechanism (3) consists of a lateral adjustment mechanism (31), a rotation mechanism (32), and an expansion mechanism (33). The lateral adjustment mechanism (31) is symmetrically distributed on the left and right sides of the top of the frame (1), and the supporting mechanism (2) is located between the two lateral adjustment mechanisms (31). The lateral adjustment mechanism (31) drives the clamping mechanism (3) to slide laterally along the top of the frame (1) to accommodate pipes of different lengths. After the lateral adjustment mechanism (31) is laterally positioned, the expansion mechanism (33) expands radially to clamp and fix the pipe being processed from the inside of the pipe. The rotation mechanism (32) drives the expansion mechanism (33) and the clamped pipe to rotate as a whole.

2. The expansion and shrinking machine as described in claim 1, characterized in that, The supporting mechanism (2) includes a first slide rail (21), a first slider (22), a first motor (23), a first screw (24), and a clamping block (25). Two first slide rails (21) are fixedly provided on the rear side of the frame (1) in a symmetrical arrangement. The first slider (22) is slidably connected on the first slide rail (21). The clamping block (25) is fixedly provided between the rear sides of the two first sliders (22). The first motor (23) is installed on the rear side of the frame (1). The first screw (24) is connected to the output shaft of the first motor (23). The clamping block (25) is threadedly connected to the first screw (24). The first motor (23) drives the first screw (24) to rotate, thereby driving the clamping block (25) and the first slider (22) to rise vertically along the first slide rail (21) and adjust the tube end to the processing height that matches the expansion and contraction mechanism (4).

3. The expansion and shrinking machine as described in claim 2, characterized in that, The lateral adjustment mechanism (31) includes a second slide rail (311), a second slider (312), a support block (313), a second motor (314), and a second screw (315). Two second slide rails (311) are fixedly provided on the left and right sides of the top of the frame (1) and are symmetrically distributed in front and behind. The second slider (312) is slidably connected on the second slide rail (311). The support block (313) is fixedly provided between the tops of the second sliders (312) on the same side. The second motor (314) is installed on the top of the frame (1). The second screw (315) is connected to the output shaft of the second motor (314). The support block (313) is threadedly connected to the second screw (315). The second motor (314) drives the second screw (315) to rotate, which drives the support block (313) to move synchronously towards or away from each other along the second slide rail (311).

4. The expansion and shrinking machine as described in claim 3, characterized in that, The rotating mechanism (32) includes a connecting frame (321), a fixed plate (322), a third motor (323), a first gear (324), a second gear (325), and a chain (326). The connecting frame (321) is rotatably connected inside the support block (313). The fixed plate (322) is fixedly installed on the left side of the connecting frame (321). The third motor (323) is installed on the top of the support block (313). The first gear (324) is connected to the output shaft of the third motor (323). The second gear (325) is fixedly installed outside the connecting frame (321). The first gear (324) and the second gear (325) transmit power through the chain (326). The third motor (323) drives the first gear (324) to rotate. The chain (326) drives the second gear (325) and the connecting frame (321) to rotate as a whole, so that the fixed plate (322) and the contact block (335) rotate synchronously, thereby driving the clamped pipe to rotate.

5. A die-expanding and shrinking machine as described in claim 4, characterized in that, The expansion mechanism (33) includes a first electric push rod (331), a connecting rod (332), a top block (333), a third slide rail (334), and a contact block (335). The first electric push rod (331) is installed on the opposite side of the two support blocks (313). The first electric push rod (331) is connected to the telescopic rod of the first electric push rod (331). The connecting rod (332) is located inside the connecting frame (321) and is slidably connected to it. The left side of the connecting rod (332) passes through the connecting frame (321) and is fixedly provided with the top block (333). Several third slide rails (334) are fixedly provided on the inner side of the disc (322). A contact block (335) is slidably connected on the third slide rail (334). An elastic element is provided between the contact block (335) and the third slide rail (334) above it. The top block (333) contacts the contact block (335) on the same side. The first electric push rod (331) pushes the connecting rod (332) and the top block (333) to move inward. The linear thrust is converted into a radial component force through the cooperation of the conical surface and the inclined surface, driving the contact block (335) to expand outward synchronously along the third slide rail (334).

6. The expansion and shrinking machine as described in claim 5, characterized in that, The expansion and contraction mechanism (4) includes a support frame (41), a fourth motor (42), a third screw (43), an upper sealing knife (44), a fourth slide rail (45), a fifth motor (46), a fourth screw (47), a lower sealing knife (48), and a fifth slide rail (49). The support frame (41) is fixedly installed on the top of the support block (313). The fourth motor (42) is installed on the top of the support frame (41). The third screw (43) is connected to the output shaft of the fourth motor (42). The upper sealing knife (44) is externally threaded to the third screw (43). The fourth slide rail (45) is fixedly installed on the top of the support frame (41). The upper sealing knife (44) and the fourth slide rail (45) are slidably connected. Next, the fourth motor (42) drives the third screw (43) to rotate, causing the upper sealing knife (44) to slide along the fourth slide rail (45). The fifth motor (46) is installed on the top of the support frame (41). The output shaft of the fifth motor (46) is connected to the fourth screw (47). The fourth screw (47) is externally threaded to the lower sealing knife (48). The upper sealing knife (44) and the lower sealing knife (48) are embedded with heating tubes. The fifth slide rail (49) is fixedly installed on the top of the support frame (41). The lower sealing knife (48) is slidably connected to the fifth slide rail (49). The fifth motor (46) drives the fourth screw (47) to rotate, causing the lower sealing knife (48) to slide along the fifth slide rail (49).

7. A die-expanding and shrinking machine as described in claim 6, characterized in that, The support frame (41) has a second electric push rod (5) installed on the front and rear sides of the bottom. The second electric push rod (5) is connected to a protective plate (6) on its telescopic rod. The telescopic rod of the second electric push rod (5) moves the protective plate (6) synchronously.

8. A die-expanding and shrinking machine as described in claim 7, characterized in that, The top of the clamping block (25) is fixedly provided with a first buffer pad (26), and a magnet (27) is fixedly provided on the inner side of the first buffer pad (26).

9. A die-expanding and shrinking machine as described in claim 8, characterized in that, A protective frame (327) is fixed on one side of the two support blocks (313) facing away from each other, and the first gear (324), the second gear (325) and the chain (326) are located inside the protective frame (327).

10. A die-expanding and shrinking machine as described in claim 9, characterized in that, A second buffer pad (336) is fixedly provided on the outside of the contact block (335).

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