High safety full protection open type press

Abstract

The application discloses a high-safety full-protection open type press, which comprises a press and a stamping device loaded on the press, the stamping device comprises an upper die plate and a lower die, the press comprises a stamping rod and a base, the upper die plate is arranged on the stamping rod, the lower die is arranged on the base, a punch pin for punching is arranged on the upper die plate, and the upper die plate and the lower die cooperate to complete the punching work, and the high-safety full-protection open type press further comprises a detection device for detecting the wear condition of the punch pin and a punch pin replacing device.

Description

Technical Field

[0001] This invention relates to the field of press technology, and in particular to a high-safety, fully protected open press. Background Technology

[0002] A press (including punch presses and hydraulic presses) is a sophisticated and versatile press. It is characterized by its wide range of applications and high production efficiency, and can be widely used in processes such as cutting, punching, blanking, bending, riveting, and forming.

[0003] Existing presses are often upgraded to improve production efficiency, such as in punching operations. For example, Chinese patent CN214391896U optimizes production efficiency. However, in actual production, when the punching hole diameter is small and the plate thickness is large, the wear on the punch increases. If the punching continues, the hole diameter will become smaller in the later stage, which will not meet the production requirements. In existing processes, the punch is replaced after a specified number of punching cycles, or the punch is manually measured after a certain stamping time, and the decision to replace the punch is made manually. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a highly safe, fully protected open-type press.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a high-safety, fully protected open-type press, comprising a press and a stamping device. The stamping device is mounted on the press and includes an upper template mounted on a stamping rod and a punch mounted on the upper template. The stamping device also includes a lower housing with a detection hole for guiding the punch's sliding motion. A detection cavity communicating with the detection hole is formed on the side wall of the detection hole. The press further includes a detection device and a punch changing device. The detection device includes a top contact elastically guided and slidably mounted in the detection cavity and a sliding rheostat connected to the top contact with a sliding block. The front end of the top contact elastically extends into the detection hole, and the punch extends downward into the detection hole. The front end of the top contact elastically contacts the side wall of the punch. Changes in the punch diameter cause different resistance values ​​on the sliding rheostat, thereby determining the punch's wear state. The punch changing device includes a punch feeding device for storing punches and a telescopic component for attracting punches. A locking device is provided on the punch; after unlocking, the punch automatically falls downward. The telescopic component can push the punch in the needle feeding device onto the upper template, thereby completing the punch replacement.

[0006] In the above scheme, preferably, the punch is a long rod type with the same diameter at the top and bottom. The punch moves downward through the detection hole, and the wear condition of the lower end of the punch is determined by comparing the resistance changes at the top and bottom ends of the punch.

[0007] In the above scheme, preferably, the locking device includes an upper limit block and a lower limit block that are elastically guided and slidably disposed on the side of the punch, and an electromagnet that can magnetically pull the upper limit block into the punch. The upper limit block and the lower limit block are locked to the needle feeding device and the upper template. When the electromagnet is energized, the upper limit block is magnetically pulled into the punch, and the punch can move downward.

[0008] In the above scheme, preferably, the upper end of the punch is provided with a guide hole, and a first pressure contact switch and a magnetic ring are provided at the bottom of the guide hole. The telescopic rod of the telescopic member can extend into the guide hole to press against the first pressure contact switch and be attracted by the magnetic ring. The first pressure contact switch controls the upper limit block to retract into the punch, and the telescopic member can push the punch to move downward.

[0009] Its beneficial effect is that after a period of punching operation, it can automatically start the inspection of the punch. When the wear is small, the punching operation continues. When the wear is large, the punch is automatically replaced. The entire inspection and replacement process is completed automatically without human intervention, reducing direct contact between personnel and equipment, thereby reducing safety accidents and improving equipment safety.

[0010] In the above scheme, preferably, a second pressure switch is provided on the upper end surface of the punch. When the telescopic member pushes the punch downward and touches the upper end surface of the punch on the upper template, the second pressure switch is pressed. The second pressure switch can also control the electromagnetic block to be energized, so that the upper limit block is sucked into the punch, and then the punch on the upper template falls down automatically.

[0011] In the above scheme, preferably, a sliding member is laterally guided and slidably arranged on the lower housing, the detection hole is located on the sliding member, and a guide groove is provided on the side of the sliding member. One end of a pull rope is connected to the sliding member, and the other end extends into the side wall of the lower housing and then extends upward to connect to the upper template. After the punch on the upper template leaves the detection hole, the pull rope is tightened, which drives the sliding member to move to one side, so that the guide groove is located below the punch.

[0012] In the above scheme, preferably, the stamping device includes an upper shell disposed on a base plate, a guide rod disposed on the upper shell, a lower shell slidably disposed on the guide rod, and a first elastic element and a second elastic element sleeved on the guide rod. The two ends of the first elastic element respectively abut against the upper end face of the upper template and the upper shell, and the two ends of the second elastic element respectively abut against the bottom surface of the lower shell and the upper end face of the lower die.

[0013] In the above scheme, preferably, during the upward movement of the upper template, the lower shell elastically contacts the upper shell, thereby keeping the lower shell stationary while the upper template continues to rise, causing the punch and the detection hole to move relative to each other, thus completing the detection of the punch.

[0014] In the above scheme, preferably, a limit plate is provided inside the upper housing, and a third pressure switch is provided on the bottom surface of the limit plate. After the upper template rises a certain distance, it presses against the limit plate, and the third pressure switch is pressed, controlling the stamping rod to stop rising.

[0015] In the above scheme, preferably, the needle feeding device includes a guide groove and a rear sealing plate. The guide groove is set on the upper housing, and the rear sealing plate is provided with a third elastic element to elastically press the punch in the guide groove. The foremost punch is located below the telescopic element and above the punch on the upper template.

[0016] Its advantage lies in the fact that multiple punches can be stored in the guide slot, allowing for repeated replacements and ensuring that the equipment can operate for a long time.

[0017] The beneficial effects of this invention are as follows: This invention provides a high-safety, fully protected open-type press that automatically starts the wear detection of the punch after a period of punching operation. When the wear is small, the punching operation continues. When the wear exceeds the set value, the punch is automatically replaced. The entire detection and replacement process is completed automatically without human intervention, reducing direct contact between personnel and equipment, thereby reducing safety accidents and improving equipment safety. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the present invention.

[0019] Figure 2 This is a schematic diagram of the stamping device of the present invention.

[0020] Figure 3 This is a cross-sectional view of the stamping device of the present invention.

[0021] Figure 4 This is a schematic diagram of the punch of the present invention.

[0022] Figure 5 This is a cross-sectional view of the stamping device of the present invention.

[0023] Figure 6 This is a cross-sectional view of the lower housing of the present invention.

[0024] Figure 7 This is a partial enlarged view of the needle feeding device of the present invention.

[0025] Figure 8 This is a partial enlarged view of the detection device of the present invention. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: See Figures 1-8A high-safety, fully protected open-type press includes a press 1, a stamping device 2, a detection device 3, and a needle changing device 4. The press 1 is equipped with a stamping rod 11 and a base 12. The stamping device 2 includes an upper template 21, a lower die 22, an upper housing 24, and a lower housing 25. The lower die 22 is mounted on the base 12, and the upper template 21 is mounted on the bottom end of the stamping rod 11. The upper die 21 is equipped with a punch 23, and the lower die 22 has a countersunk hole. The stamping rod 11 drives the upper template 21 to move downward, and the punch 23 cooperates with the countersunk hole to perform punching operations on the plate on the lower die 22.

[0027] The upper housing 24 is fixedly mounted on the base plate of the stamping device by a 7-shaped fixing bracket. One end of the guide rod 241 is provided on the upper housing 24, and the other end is provided on the lower die 22. The upper template 21 and the lower housing 25 are guided and slidably mounted on the guide rod 241. A first elastic element 242 and a second elastic element 243 are sleeved on the guide rod 241. The two ends of the first elastic element 242 respectively abut against the upper end face of the upper template 21 and the upper housing 24. The two ends of the second elastic element 243 respectively abut against the bottom surface of the lower housing 25 and the upper end face of the lower die 22. A detection hole 251 is provided on the lower housing 25, and the punch 23 of the upper template 21 passes through the detection hole 251.

[0028] In the initial state, the lower end of the upper template 21 presses against the lower housing 25, causing the lower housing 25 to separate from the upper housing 24. The first elastic element 242 is in a compressed state. At this time, the punch rod 11 moves up and down under the action of the hydraulic device inside the press 1. When moving downward, the upper template 21 drives the lower housing 25 to move downward together. The punch 23 on the upper template 21 cooperates with the countersunk hole on the lower die 22 to perform punching operation on the plate on the lower die 22. When the punch rod 11 moves upward, it drives the upper template 21 to move upward, and the downward pressure on the lower housing 25 disappears. Then, under the action of the first elastic element 242, the elastic element touches the upper template 21 and moves upward with the upper template 21. During the stroke of the punch rod 11 moving up and down, the lower housing 25 does not contact the upper housing 25. Thus, during continuous punching operation, the lower housing 25 moves synchronously with the upper template 21.

[0029] A sliding member 252 is laterally guided and elastically slidably disposed on the lower housing 25. A detection hole 251 is located on the sliding member 252. A detection cavity 2511 is formed on the side wall of the detection hole 251. The detection device 3 includes a top contact 31 and a sliding rheostat 32. The top contact 31 is elastically guided and slidably disposed on the side of the punch 23. The sliding rheostat 32 is also disposed in the detection cavity 2511 and located on one side of the top contact 31. The sliding block on the sliding rheostat 32 is disposed on the top contact 31. When the top contact 31 moves back and forth, the resistance value on the sliding rheostat 32 changes. The sliding rheostat 32 is connected to the control circuit. The control terminal identifies the wear condition of the punch 23 by detecting the change in current. A guide groove 2521 is provided on the side of the sliding member 252. One end of a pull rope 253 is connected to the sliding member 252, and the other end extends into the side wall of the lower housing 25 and then extends upward to connect to the upper template 21.

[0030] During normal punching operations, the punch 23 and the detection hole 251 are relatively stationary. At this time, the front end of the top contact 31 is elastic. After a set number of normal punching operations, the control system controls the punching rod 11 to move upward. During the upward movement of the punching rod 11, the upper template 21 is driven to move upward. During the movement, the lower housing 25 elastically contacts the upper housing 24, and then the lower housing 25 stops moving upward, while the upper template 21 continues to move upward. The punch 23 and the detection hole 251 move relative to each other, and the top contact 31 moves on the punch 23, thereby detecting the change in the diameter of the punch 23 from top to bottom until the top contact 31 no longer contacts the punch 23. At this time, the punch 23 has been completely detected, and the punching rod 11 stops moving. When the change in diameter at the upper and lower ends is small, that is, when the change in current in the control circuit does not exceed the set value, the punching rod 11 moves downward to continue the punching operation. When the change in diameter at the upper and lower ends is large, that is, when the change in current in the control circuit exceeds the set value, the punching rod 11 continues to move upward.

[0031] The upper housing 24 is provided with a limiting plate 244, and a third pressure switch is provided on the bottom surface of the limiting plate 244. After the upper template 21 rises a certain distance, it presses against the limiting plate 244, and the third pressure switch is pressed, controlling the punch rod 11 to stop rising. At this time, the lower end of the punch 23 on the upper template 21 is higher than the upper end surface of the sliding member 252. When the punch 23 leaves the upper end surface of the sliding member 252, the pull rope 253 is tightened. At this time, the upper template 21 continues to move upward, that is, the lower end of the punch 23 is separated from the upper end surface of the sliding member 252. The upper template 21 drives the sliding member 252 to move to one side through the pull rope 253, that is, the detection hole 251 leaves the bottom of the punch 23, and the guide groove 2521 enters the bottom of the punch 23. When the upper template 21 touches the third pressure switch, the guide groove 2521 is located below the punch 23.

[0032] The needle changing device 4 includes a telescopic member 41 and a needle feeding device 42. The telescopic member 41 is an electric telescopic rod and is mounted on the upper housing 24. The needle feeding device 42 includes a guide groove 421 and a rear sealing plate 422. The guide groove 421 is mounted on the upper housing 24. The rear sealing plate 422 is locked to the rear end opening of the guide groove 421 by bolts or buckles. The punch 23 is loaded onto the guide groove 421 through the rear end opening of the guide groove 421. A third elastic member 423 is provided on the rear sealing plate 422. After the rear sealing plate 422 is fixed on the guide groove 421, the front end of the third elastic member 423 touches the punch 23, thereby elastically pressing the punch 23 in the guide groove 421. The punch 23 located at the front end of the guide groove 421 is located below the telescopic member 41 and above the punch 23 on the upper template 21.

[0033] The punch 23 has a guide hole 233 at its upper end, and a first pressure switch and a magnetic ring are provided at the bottom of the guide hole 233. A second pressure switch is provided on the upper surface of the punch 23. An upper limit block 231 and a lower limit block 232 are slidably provided on the side wall of the punch 23. The upper limit block 231 and the lower limit block 232 cooperate to slide the punch 23 on the guide groove 421. The upper limit block 231 and the lower limit block 232 cooperate to lock the punch 23 on the punch hole of the upper template 21. An electromagnetic block is provided inside the punch 23. When the electromagnetic block is energized, it can draw the upper limit block 231 into the punch 23, thereby causing the upper limit of the punch 23 to disappear and the punch 23 to move downward. The lower limit block 232 is elastically guided and slidably disposed on the side of the punch 23, and the lower end surface of the lower limit block 232 is inclined. When the lower end inclined surface is pressed, it can automatically retract into the punch 23. When the top contact disappears, the lower limit block 232 automatically extends outward. When the first pressure switch and the second pressure switch are pressed, the electromagnetic block can be energized to draw the upper limit block 231 into the punch 23.

[0034] When the upper template 21 presses against the third pressure switch, and the punching rod 11 stops moving upward, the telescopic member 41 begins to extend downward. The telescopic rod of the telescopic member 41 extends into the guide hole 233 of the punch 23 on the guide groove 421 and presses against the first pressure switch. After the telescopic rod extends into the guide hole 233, the magnetic ring magnetically attracts the telescopic rod. At this time, the first pressure switch is pressed, the electromagnetic block is energized, and the upper limit block 231 is drawn into the punch 23. Then, the guide groove 421 releases the limit on the downward movement of the punch 23. At this time, the telescopic rod can drive the punch 23 to move downward together, and through the guidance of the guide hole 233, the punch 23 is prevented from moving, and it can accurately press downward against the upper end surface of the punch 23 on the upper template 21. When the second pressure switch is pressed, the upper limit block 231 of the punch 23 on the upper template 21 retracts into the punch 23, and then the punch 23 automatically falls downward onto the guide groove 2521 below, and then automatically slides outward.

[0035] The power source inside the punch 23 can be a small storage battery installed inside the punch 23, or electrode contact pieces can be installed at the punch hole position of the upper template 21 and the bottom of the telescopic rod. When the punch 23 contacts the electrode contact pieces, the circuit inside the punch 23 is powered.

[0036] After the punch 23 on the upper template 21 falls off, the telescopic rod drives the punch 23 to continue moving downward and enter the punch hole of the upper template 21. The lower limit block 232 on the punch 23 presses against the upper edge of the punch hole and elastically retracts into the punch 23. After the lower limit block 232 elastically retracts, it presses against the fourth pressure switch inside, thereby de-energizing the electromagnetic block. The upper limit block 231 at the upper end of the punch 23 automatically pops out. After the lower limit block 232 passes through the punch hole, it automatically pops out. At this time, the upper limit block 231 and the lower limit block 232 are located at the upper and lower ends of the upper template 21, respectively. When the lower limit block 232 automatically pops out, the pressure on the fourth pressure switch disappears. At this time, the telescopic component 41 begins to rise, and the telescopic rod disengages from the punch 23 and returns to the initial state. This completes the automatic replacement of the punch 23.

[0037] Its working principle or usage method is as follows: In the initial state, the lower end of the upper template 21 presses against the lower housing 25, causing the lower housing 25 to separate from the upper housing 24. The first elastic element 242 is in a compressed state. At this time, the stamping rod 11 moves up and down under the action of the hydraulic device inside the press 1. When moving downward, the upper template 21 drives the lower housing 25 to move downward together. The punch 23 on the upper template 21 cooperates with the countersunk hole on the lower die 22 to perform punching operation on the plate on the lower die 22. When the stamping rod 11 moves upward, it drives the upper template 21 to move upward, and the downward pressure on the lower housing 25 disappears. Then, under the action of the first elastic element 242, the elastic element touches the upper template 21 and moves upward with the upper template 21. The lower housing 25 moves synchronously with the upper template 21.

[0038] After a set number of normal punching operations, the control system controls the punching rod 11 to move upward. During the upward movement of the punching rod 11, the upper template 21 moves upward, and the lower housing 25 elastically contacts the upper housing 24 and stops moving upward. The upper template 21 continues to move upward, and the punch 23 moves relative to the detection hole 251. The top contact 31 moves on the punch 23, thereby detecting the diameter change of the punch 23 from top to bottom until the top contact 31 no longer contacts the punch 23. At this time, the punch 23 has been completely detected, and the punching rod 11 stops moving. When the diameter change at the upper and lower ends is small, that is, when the current change in the control circuit does not exceed the set value, the punching rod 11 moves downward to continue the punching operation. When the diameter change at the upper and lower ends is large, that is, when the current change in the control circuit exceeds the set value, the punching rod 11 starts to move upward again.

[0039] The upper template 21 continues to move upward until it stops moving upward when it touches the third pressure switch. During the upward movement, the guide groove 2521 is pulled to a position below the punch 23. At this time, the telescopic component 41 begins to extend downward, and the telescopic rod extends into the guide hole 233. The magnetic ring of the punch 23 is magnetically attracted to the telescopic rod. At this time, the first pressure switch is pressed, and the electromagnetic block is energized to draw the upper limit block 231 into the punch 23. Then, the guide groove 421 releases the limit on the downward movement of the punch 23. At this time, the telescopic rod can drive the punch 23 to move downward together, and through the guidance of the guide hole 233, the punch 23 is prevented from moving. It can accurately press downward onto the upper end surface of the punch 23 on the upper template 21, thereby pressing the second pressure switch. The upper limit block 231 of the punch 23 on the upper template 21 retracts into the punch 23, and then the punch 23 automatically falls downward onto the guide groove 2521 below and automatically slides outward.

[0040] After the punch 23 on the upper template 21 falls, the telescopic rod drives the punch 23 to continue moving downwards and into the punch hole of the upper template 21. The lower limit block 232 on the punch 23 presses against the upper edge of the punch hole and elastically retracts into the punch 23. After the lower limit block 232 elastically retracts, it presses against the fourth pressure switch inside, thereby de-energizing the electromagnetic block. The upper limit block 231 at the upper end of the punch 23 automatically pops outwards. After the lower limit block 232 passes through the punch hole, it automatically pops outwards. At this time, the upper limit block... Block 231 and lower limit block 232 are located at the upper and lower ends of the upper template 21, respectively. When the lower limit block 232 pops out automatically, the pressure on the fourth pressure switch disappears. At this time, the telescopic component 41 begins to rise, the telescopic rod disengages from the punch 23 and returns to the initial state, and the punching rod 11 extends downward. At this time, the new punch 23 on the upper template 21 re-enters the detection hole 251, and the upper template 21 presses against the lower housing 25 again. Everything returns to the initial state, and the automatic replacement of the punch 23 is completed.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-safety, fully protected open-type press, comprising a press (1) and a stamping device (2), wherein the stamping device (2) is mounted on the press (1), and the stamping device (2) comprises an upper template (21) mounted on a stamping rod and a punch (23) mounted on the upper template (21), characterized in that: It also includes a detection device (3) and a needle changing device (4). The stamping device (2) also includes a lower housing (25). The lower housing (25) is provided with a detection hole (251) for guiding and sliding the punch (23), and a detection cavity (2511) communicating with the detection hole (251) is opened on the side wall of the detection hole (251). The detection device (3) includes a top contact (31) that is elastically guided and slidably disposed in the detection cavity (2511) and a sliding rheostat (32) that is connected to the top contact (31) by a sliding block. The front end of the top contact (31) elastically extends into the detection hole (251), and the punch (23) extends downward into the detection hole (251). The front end of the top contact (31) elastically touches the side wall of the punch (23). The change in the diameter of the punch (23) causes the sliding rheostat (32) to be at different resistance values, thereby determining the wear state of the punch (23). The needle changing device (4) includes a needle feeding device (42) for storing the punch (23) and a telescopic component (41) for adsorbing the punch (23). The punch (23) is equipped with a locking device. After unlocking, the punch (23) automatically falls downward. The telescopic component (41) can push the punch (23) in the needle feeding device (42) onto the upper template (21) to complete the punch replacement. The locking device includes an upper limit block (231) and a lower limit block (232) that are elastically guided and slidably disposed on the side of the punch (23), and an electromagnet that can magnetically pull the upper limit block (231) into the punch (23). The upper limit block (231) and the lower limit block (232) lock the punch (23) on the needle feeding device (42) and the upper template (21). When the electromagnet is energized, the upper limit block (231) is magnetically pulled into the punch (23), and the punch (23) can move downward. The stamping device (2) includes an upper housing (24) on a base plate, a guide rod (241) on the upper housing (24), and a lower housing (25) slidably mounted on the guide rod (241). A first elastic element (242) and a second elastic element (243) are sleeved on the guide rod (241). The two ends of the first elastic element (242) abut against the upper end face of the upper template (21) and the upper housing (24) respectively. The two ends of the second elastic element (243) abut against the bottom surface of the lower housing (25) and the upper end face of the lower die (22) respectively. As the upper template (21) rises, the lower shell (25) elastically contacts the upper shell (24), and the lower shell (25) remains stationary while the upper template (21) continues to rise, causing the punch (23) to move relative to the detection hole (251), thereby completing the detection of the punch (23).

2. The high-safety, fully protected open-type press according to claim 1, characterized in that: The punch (23) is a long rod with the same diameter at the top and bottom. The punch (23) moves down through the detection hole (251). By comparing the resistance changes at the top and bottom of the punch (23), the wear condition of the bottom of the punch (23) can be determined.

3. The high-safety, fully protected open-type press according to claim 1, characterized in that: The upper end of the punch (23) is provided with a guide hole (233). A first pressure switch and a magnetic ring are provided at the bottom of the guide hole (233). The telescopic rod of the telescopic member (41) can be inserted into the guide hole (233) to press against the first pressure switch and be attracted by the magnetic ring. The first pressure switch controls the upper limit block (231) to retract into the punch (23). The telescopic member (41) can push the punch (23) to move downward.

4. The high-safety, fully protected open press according to claim 3, characterized in that: A second pressure switch is provided on the upper surface of the punch (23). When the telescopic member (41) pushes the punch (23) downward and touches the upper surface of the punch (23) on the upper template (21), the second pressure switch is pressed. The second pressure switch can also control the electromagnetic block to be energized, so that the upper limit block (231) is sucked into the punch (23), and then the punch (23) on the upper template (21) automatically falls downward.

5. The high-safety, fully protected open-type press according to claim 1, characterized in that: The lower housing (25) is laterally guided and slidably provided with a sliding member (252). The detection hole (251) is located on the sliding member (252), and the sliding member (252) is provided with a guide groove (2521) on its side. One end of a pull rope (253) is connected to the sliding member (252). The other end of the pull rope (253) extends into the side wall of the lower housing (25) and then extends upward to connect to the upper template (21). After the punch (23) on the upper template (21) leaves the detection hole (251), the pull rope (253) is tightened, which drives the sliding member (252) to move to one side, so that the guide groove (2521) is located below the punch (23).

6. The high-safety, fully protected open press according to claim 1, characterized in that: The upper housing (24) is provided with a limit plate (244), and a third pressure switch is provided on the bottom surface of the limit plate (244). After the upper template (21) rises a certain distance, it presses against the limit plate (244), and the third pressure switch is pressed, controlling the stamping rod to stop rising.

7. The high-safety, fully protected open-type press according to claim 3, characterized in that: The needle feeding device (42) includes a guide groove (421) and a rear sealing plate (422). The guide groove (421) is set on the upper housing (24), and a third elastic element (423) is set on the rear sealing plate (422) to elastically press the punch (23) of the guide groove (421). The foremost punch (23) is located below the telescopic member (41) and above the punch (23) on the upper template (21).

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