Stretching pad of punching machine and punching machine

Abstract

The utility model relates to a stretching pad of a punching machine and the punching machine. The stretching pad comprises a bearing part; the driving part is used for driving the bearing part to ascend or descend; the hydraulic cylinders are distributed on the upper surface of the bearing part; the upper ends of the multiple supporting rods are used for abutting against the blank holder, the lower ends of the multiple supporting rods are used for directly facing the corresponding first piston heads, and the multiple first cylinder bodies communicate with one another, so that when any one of the multiple first piston heads moves downwards, at least one of the other first piston heads moves upwards. The bearing part moves upwards to drive the multiple supporting rods to move upwards, the highest supporting rod can abut against the blank holder firstly and push the opposite first piston heads to move downwards in the first cylinder body under the counter-acting force, and therefore the rest first piston heads can move upwards in the first cylinder body under the action of the first piston heads moving downwards, and the first piston heads move downwards. And the blank holder forces applied to the blank holder by all the supporting rods are the same, so that the forming quality of a workpiece is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of punching machines, and in particular to a stretching pad of a punching machine and a punching machine. Background Art

[0002] The stretch pad is the main component of the punching machine. Its function is to provide pressure to the blank holder ring to press the sheet before drawing, so as to provide a stable blank holder force during the forming process, ensure the stability of the flow rate during the sheet forming process, and thus improve the drawing quality of the part.

[0003] In the related art, the stretching pad mainly includes a bearing part and a main cylinder for driving the bearing part to rise and fall. A push rod is arranged at the top of the bearing part to press the blank holder. However, when the main cylinder drives the bearing part to rise, due to the low control accuracy, the bearing part is tilted when it is lifted, resulting in inconsistent lifting heights of the push rod at the top of the direction, that is, inconsistent blank holder forces provided to various positions of the blank holder, thus affecting the molding quality of the workpiece. Utility Model Content

[0004] An object of the present disclosure is to provide a stretching pad of a punching machine and a punching machine to at least partially solve the problems existing in the related art.

[0005] In order to achieve the above-mentioned purpose, the present disclosure provides a stretching pad of a stamping machine, comprising: a bearing part; a driving part, used to drive the bearing part to rise or fall; a plurality of hydraulic cylinders, at least distributed on the upper surface of the bearing part near the edge, the hydraulic cylinder comprising a first cylinder body and a first piston head arranged in the first cylinder body; and a plurality of support rods, each of which has an upper end used to abut against a pressure ring of the stamping machine when the support rod moves upward, and a lower end used to face the corresponding first piston head so as to be pushed upward by the first piston head, wherein the plurality of first cylinder bodies are connected to each other, so that when any one of the plurality of first piston heads moves downward, at least one of the remaining first piston heads moves upward.

[0006] Optionally, the first piston head is used to divide the first cylinder into a first space and a second space from top to bottom, the second space contains a liquid medium, and a plurality of the second spaces are interconnected.

[0007] Optionally, the hydraulic cylinder further comprises a first piston rod whose lower end is connected to the first piston head and whose upper end extends out of the first cylinder body, and the lower ends of the plurality of support rods are respectively used to face the corresponding first piston rods.

[0008] Optionally, the stamping machine includes a workbench having a plurality of through holes, and the pressure ring is arranged at a position on the workbench opposite to the plurality of through holes, wherein the plurality of support rods are respectively hung in corresponding through holes and can move upward or downward along the through holes.

[0009] Optionally, the through hole is constructed as a stepped hole including a large diameter section and a small diameter section, the large diameter section is located above the small diameter section, the upper end of the support rod extends into the large diameter section and is provided with a large head section matching the shape of the large diameter section.

[0010] Optionally, the plurality of hydraulic cylinders are evenly distributed on the upper surface of the bearing portion, and the upper end of each of the hydraulic cylinders faces one of the support rods.

[0011] Optionally, the driving part includes a plurality of cylinders disposed at the lower side of the bearing part, and the cylinders are used to drive the bearing part to rise or fall.

[0012] Optionally, it also includes a plurality of adjustment devices arranged on the lower side of the bearing part, and the adjustment devices include: a second cylinder body; a second piston head, which is arranged in the second cylinder body; a second piston rod, one end of which is connected to the second piston head, and the other end of which extends upward from the second cylinder body and is connected to the bearing part; a limit member, which at least partially extends into the second cylinder body to limit the range of movement of the second piston head; and an adjustment part, which is used to adjust the position of the limit member in the second cylinder body.

[0013] Optionally, it also includes a plurality of locking devices for locking the load-bearing part, the locking devices including: a third cylinder body; a third piston head, arranged in the third cylinder body to divide the third cylinder body into a third space and a fourth space; a third piston rod, one end of which is connected to the third piston head, and the other end of which extends upward from the third cylinder body and is connected to the load-bearing part; and an oil pipe, connecting the third space and the fourth space, the oil pipe being provided with a valve.

[0014] According to a second aspect of the present disclosure, a punching machine is provided, comprising the above-mentioned stretching pad of the punching machine.

[0015] Through the above technical scheme, when it is necessary to provide a blank holding force for the blank holding ring of the punching machine through the stretching pad, the driving part can be controlled to drive the bearing part to move upward, and the bearing part drives multiple hydraulic cylinders to move upward synchronously until multiple first piston heads abut against the lower side of multiple support rods and further push the multiple support rods to move upward. Due to the driving error of the driving part, the bearing part is tilted, especially when the driving part is a cylinder, its driving accuracy is poor and the bearing part is tilted greatly. Therefore, in the process of multiple support rods moving upward, the highest support rod will first abut against the blank holding ring, and push the first piston head opposite to it under the reaction force of the blank holding ring. The cylinder body moves downward, and since the multiple first cylinder bodies are interconnected, the remaining first piston heads will move upward in the corresponding first cylinder bodies under the action of the downwardly moving first piston heads (liquid pressure), thereby pushing the corresponding support rods to move upward; when the highest support rod is consistent with the second highest support rod (which can be multiple) in height, the highest and second highest support rods can simultaneously drive the corresponding first piston heads to continue to move downward under the reaction of the blank holder, and repeat this process until the top ends of the multiple support rods are consistent in height, then the process stops. At this time, the blank holding forces applied to the blank holder by each support rod are the same, thereby improving the molding quality of the part.

[0016] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0018] Figure 1 is a schematic diagram of a stretching pad of a punching machine exemplarily shown according to the present disclosure;

[0019] Figure 2 and Figure 3 yes Figure 1 A schematic diagram of the communication between multiple first cylinder bodies shown in FIG.

[0020] Description of Reference Numerals

[0021] 100-bearing part; 200-driving part; 210-cylinder; 300-hydraulic cylinder; 310-first cylinder body; 311-first space; 312-second space; 320-first piston head; 330-first piston rod; 400-support rod; 510-blank pressing ring; 520-workbench; 521-through hole; 610-second cylinder body; 620-second piston head; 630-second piston rod; 640-limiting member; 641-sleeve structure; 650-adjusting part; 651-worm; 652-worm wheel; 710-third cylinder body; 711-third space; 712-fourth space; 720-third piston head; 730-third piston rod; 740-oil pipe; 750-valve. DETAILED DESCRIPTION

[0022] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0023] In the present disclosure, unless otherwise stated, directional words such as "upper" and "lower" may be based on the structure of the relevant parts themselves, or may be based on the orientation of the relevant parts when used in combination. For example: the first piston head is used to divide the first cylinder body into a first space and a second space from top to bottom, and "upper" and "lower" here are based on the height direction of the stretching pad when in use, that is, the height direction perpendicular to the ground, and "from top to bottom" refers to a position away from the ground toward a position close to the ground; the "lower ends" of multiple support rods are respectively used to face the corresponding first piston rods, and the "lower end" here refers to the end of the support rod close to the ground. In the present disclosure, specific references to "upper" and "lower" may be made to the following: Figure 1 The direction of the arrow is shown in .

[0024] In the present disclosure, the terms "first", "second", etc. are used to distinguish one element from another element, and do not have order and importance. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0025] Reference Figure 1-Figure 3The present disclosure exemplarily shows a stretching pad of a stamping machine, including a bearing part 100, a driving part 200 for driving the bearing part 100 to rise or fall, a plurality of hydraulic cylinders 300 and a plurality of support rods 400. The plurality of hydraulic cylinders 300 are at least distributed at positions close to the edge of the upper surface of the bearing part 100. The hydraulic cylinder 300 includes a first cylinder body 310 and a first piston head 320 disposed in the first cylinder body 310. The upper ends of the plurality of support rods 400 are respectively used to abut against the blank holder 510 of the stamping machine when the support rod 400 moves upward, and the lower ends are used to face the corresponding first piston head 320 so as to be pushed upward by the first piston head 320. Among them, the plurality of first cylinder bodies 310 are connected to each other, so that when any first piston head 320 among the plurality of first piston heads 320 moves downward, at least one of the remaining first piston heads 320 moves upward. The present disclosure does not limit the bearing part 100 , which may be a square box, a bearing plate, etc., as long as it can be driven to rise or fall by the driving part 200 and a hydraulic cylinder 300 can be installed on the upper surface.

[0026] It should be explained that the “lower end is used to face the corresponding first piston head 320” here means that the support rod 400 is located above the first piston head 320, so that the corresponding support rod 400 can be pushed when the first piston head 320 moves upward. In some embodiments, the first piston head 320 can directly contact the support rod 400 and push the support rod 400. In this case, the upper side of the first cylinder body 310 can be configured as an opening to allow the lower end of the support rod 400 to extend into. In addition, in some other embodiments, the first piston head 320 can indirectly push the support rod 400 to move through the first piston rod 330 mentioned below.

[0027] The present disclosure does not limit how the multiple first cylinder bodies 310 are interconnected. For example, when the first cylinder body 310 is divided into the first space and the second space mentioned below by the first piston head 320, the multiple first spaces may be interconnected. Alternatively, in some other embodiments, the multiple second spaces may be interconnected, as long as when any first piston head 320 among the multiple first piston heads 320 moves downward, at least one of the other first piston heads 320 moves upward.

[0028] By using the above technical solution, when it is necessary to provide a blank holding force for the blank holding ring 510 of the punching machine through a stretching pad, the driving part 200 can be controlled to drive the bearing part 100 to move upward, and the bearing part 100 drives the multiple hydraulic cylinders 300 to move upward synchronously until the multiple first piston heads 320 reach the lower side of the multiple support rods 400 and further push the multiple support rods 400 to move upward. Due to the driving error of the driving part 200, the bearing part 100 is tilted. Especially when the driving part 200 is a cylinder, its driving accuracy is poor and the bearing part 100 is tilted greatly (the top height of the support rod 400 is inconsistent). Therefore, in the process of multiple support rods 400 moving upward, the highest support rod 400 will first hit the pressure ring 510, and under the reaction force of the pressure ring 510, push the first piston head 320 opposite to it to move downward in the first cylinder body 310. Since the multiple first cylinder bodies 310 are interconnected, the remaining first piston heads 320 will move upward in the corresponding first cylinder bodies 310 under the action of the downward moving first piston heads 320 (liquid pressure), thereby pushing the corresponding support rods 400 to move upward; when the highest support rod 400 and the second highest support rod 400 (which can be multiple) are at the same height, the highest and second highest support rods 400 can simultaneously drive the corresponding first piston heads to continue to move downward under the reaction of the pressure ring 510, and repeat this process until the top heights of the multiple support rods 400 are consistent and the process stops. At this time, the pressure applied to the pressure ring 510 by each support rod 400 is the same, thereby improving the molding quality of the part.

[0029] Reference Figure 1-Figure 3 In the embodiment of the present disclosure, the first piston head 320 can be used to divide the first cylinder body 310 into a first space 311 and a second space 312 from top to bottom, and the second space 312 can contain a liquid medium, and multiple second spaces 312 are interconnected. With such a design, when one of the first piston heads 320 moves downward, it will push the liquid on the lower side to flow into at least one of the remaining second spaces 312, and then push the corresponding first piston head 320 to drive the corresponding support rod 400 to move upward through the liquid force. In addition, in some other embodiments, liquid medium can be contained in multiple first spaces 311, and multiple first spaces 311 are interconnected. With such a design, when a first piston head 320 moves downward, the first space 311 forms a partial vacuum, and then the liquid medium of at least one of the remaining first spaces 311 can be drawn into the first space 311, and then the first space 311 from which the liquid is drawn forms a partial vacuum, so that the first piston head 320 corresponding to it moves upward, and the above-mentioned technical effect is achieved.

[0030] Reference Figure 1-Figure 3In the embodiment of the present disclosure, the hydraulic cylinder 300 may further include a first piston rod 330 whose lower end is connected to the first piston head 320 and whose upper end extends out of the first cylinder body 310, and the lower ends of the plurality of support rods 400 may be respectively used to face the corresponding first piston rods 330. With such a design, by extending the first piston rod 330 out of the first cylinder body 310 and cooperating with the support rod 400, the support rod 400 may be pushed to move upward when the driving part 200 drives the bearing part 100 to move upward by a very small stroke, thereby improving the response speed of the stretching pad.

[0031] Reference Figure 1 In an embodiment of the present disclosure, the punching machine may include a workbench 520, and the workbench 520 may be provided with a plurality of through holes 521, and the blank holder 510 may be arranged at a position on the workbench 520 opposite to the plurality of through holes 521. Among them, a plurality of support rods 400 may be hung in corresponding through holes 521, respectively, and may move upward or downward along the through holes 521. With such a design, when the plurality of support rods 400 are hung in corresponding through holes 521 and the driving part 200 drives the bearing part 100 to move upward, the hydraulic cylinder 300 may follow the upward movement to abut against the support rod 400 and push the support rod 400 to move upward, so that the upper end of the support rod 400 may move upward along the through hole 521 and abut against the blank holder 510. When the driving part 200 drives the bearing part 100 to move downward, the hydraulic cylinder 300 can follow the downward movement and have a tendency to separate from the support rod 400. At this time, the support rod 400 can move downward along the through hole 521 under the action of its own weight to separate from the blank holder 510. In addition, in some other embodiments, the lower end of the support rod 400 can be directly connected to the first piston head 320 or the aforementioned first piston rod 330, so as to be able to follow the bearing part 100 to move upward or downward.

[0032] The present disclosure does not limit how the support rod 400 is hung on the through hole 521. In the embodiment of the present disclosure, the through hole 521 can be constructed as a stepped hole including a large diameter section and a small diameter section, the large diameter section is located on the upper side of the small diameter section, and the upper end of the support rod 400 can extend into the large diameter section and be provided with a large head section matching the shape of the large diameter section. With such a design, the cooperation of the large head section and the small diameter section can limit the support rod 400 from being separated from the workbench 520 under the action of gravity. During installation, the support rod 400 can be passed through the through hole 521 from top to bottom until the large head section is located at the large diameter section.

[0033] In the embodiment of the present disclosure, the large head section can be integrally formed with the support rod 400. In addition, in some other embodiments, the large head section can be detachably mounted on the support rod 400.

[0034] In the embodiment of the present disclosure, a plurality of hydraulic cylinders 300 can be evenly distributed on the upper surface of the bearing part 100, and the upper end of each hydraulic cylinder 300 can be directly opposite to a support rod 400. Such a design can effectively improve the applicability of the stretching pad. Specifically: when the punching machine is applied to the first mold (corresponding to the first blank holder), the plurality of hydraulic cylinders 300 can follow the bearing part 100 to move upward to drive the plurality of support rods 400 to move upward, and part of the support rods 400 corresponding to the first blank holder can be pressed against the first blank holder, and the remaining support rods 400 do not play the role of blank holder; when the punching machine needs to be applied to the second mold (corresponding to the second blank holder), at this time, since the second blank holder has a different structure from the first blank holder, the corresponding support rod 400 that plays the role of blank holder is different, so another part of the plurality of support rods 400 (different from the first mold) can play the role of supporting the blank holder, and there is no need to replace the stretching pad. Alternatively, when the punching machine is used for double molds, the support rod 400 at the edge position can be used for the first blank holder of the first mold, and the support rod 400 at the center position can be used for the second blank holder of the second mold.

[0035] The present disclosure does not limit the structure of the driving unit 200. For example, in an embodiment of the present disclosure, the driving unit 200 may include a plurality of cylinders 210 disposed on the lower side of the carrying unit 100, and the cylinders 210 may be used to drive the carrying unit 100 to rise or fall. In addition, in some other embodiments, the driving unit 200 may also be a hydraulic cylinder, a servo motor, etc.

[0036] Reference Figure 1 In the embodiment of the present disclosure, the stretching pad of the punching machine may further include a plurality of adjusting devices disposed on the lower side of the bearing part 100, and the adjusting devices may include: a second cylinder 610; a second piston head 620, disposed in the second cylinder 610; a second piston rod 630, one end of which is connected to the second piston head 620, and the other end of which extends upward from the second cylinder 610 and is connected to the bearing part 100, which may be specifically screwed; a stopper 640, which at least partially extends into the second cylinder 610 to limit the range of motion of the second piston head 620; and an adjusting part 650, which is used to adjust the position of the stopper 640 in the second cylinder 610. Since the drawing strokes of the punching machine corresponding to different parts are different, in order to correspond to the production of multiple varieties, the adjusting device may preset the movement stroke of the bearing part 100 according to the specific different products. Specifically, the limit member 640 can be controlled to move to a preset position through the adjustment part 650, and the movement range of the second piston head 620 in the second cylinder body 610 can be limited by the limit member 640. Since the second piston rod 630 is connected between the second piston head 620 and the bearing part 100, the movement range of the bearing part 100 can be limited by the limit member 640.

[0037] The present disclosure does not limit the specific structure of the stopper 640 and the adjustment part 650. For example, in some embodiments, the stopper 640 can be a sleeve structure 641 that is sleeved on the second piston rod 630 and can move axially relative to the second piston rod 630. The sleeve structure 641 can at least partially extend into the second cylinder body 610 and limit the movement range of the second piston head 620 by the end extending into the second cylinder body 610 (the stopper 640 is dynamically sealed with the second cylinder body 610 and the second piston rod 630 to prevent the liquid in the second cylinder body 610 from flowing out). Specifically, Figure 1 In the illustrated embodiment, the adjusting portion 650 may include a motor (not shown in the figure), a worm 651, and a worm wheel 652 matched with the worm 651. The inner side of the worm wheel 652 is hollow and provided with an internal thread. The sleeve structure 641 is provided with an external thread. The worm wheel 652 is screwed on the sleeve structure 641 to drive the sleeve structure 641 to move along the axis direction of the second piston rod 630 when the worm wheel 652 rotates. In order to limit the rotation of the sleeve structure 641, a guide structure (not shown in the figure) may be additionally provided to only allow the sleeve structure 641 to move along the axial direction. In addition, in some other embodiments, the limiter 640 and the adjusting portion 650 may also include a motor and a crank slider mechanism that is transmission-connected to the motor, wherein the slider is connected to the limiter 640 (e.g., the sleeve structure) to drive the limiter 640 to move, as long as the adjusting portion 650 can drive the limiter 640 to move in the second cylinder body 610.

[0038] Reference Figure 1 In the embodiment of the present disclosure, the stretching pad of the punching machine may further include a plurality of locking devices for locking the bearing part 100, and the locking devices may include: a third cylinder 710; a third piston head 720, which is disposed in the third cylinder 710 to divide the third cylinder 710 into a third space 711 and a fourth space 712; a third piston rod 730, one end of which is connected to the third piston head 720, and the other end of which extends upward from the third cylinder 710 and connects the bearing part 100; and an oil pipe 740, which connects the third space 711 and the fourth space 712, and the oil pipe 740 may be provided with a valve 750. With such a design, when the bearing part 100 needs to rise or fall, the valve 750 is opened, and at this time, the third space 711 and the fourth space 712 are connected, and the third piston head 720 and the third piston rod 730 can rise or fall with the bearing part 100. When it is necessary to lock the bearing part 100 and delay its rising to prevent interference with the picking robot, the valve 750 can be closed. At this time, the third space 711 and the fourth space 712 are cut off from each other. In this case, the third piston head 720 cannot move in the up and down directions in the third cylinder body 710. Since the third piston rod 730 is connected between the third piston head 720 and the bearing part 100, the bearing part 100 can be locked by the third piston head 720.

[0039] According to a second aspect of the present disclosure, a punching machine is provided, comprising the above-mentioned stretching pad of the punching machine. Since the punching machine has all the beneficial effects of the above-mentioned stretching pad of the punching machine, they are not described in detail here.

[0040] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0041] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0042] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A stretching pad for a punching machine, characterized in that: include: load-bearing part; A driving unit, used for driving the bearing unit to rise or fall; A plurality of hydraulic cylinders, at least distributed at positions close to the edge of the upper surface of the bearing portion, the hydraulic cylinders comprising a first cylinder body and a first piston head disposed in the first cylinder body; as well as A plurality of support rods, each having an upper end for abutting against a blank holder of a punching machine when the support rod moves upward, and a lower end for facing a corresponding first piston head so as to be pushed upward by the first piston head. Wherein, a plurality of the first cylinder bodies are interconnected, so that when any one of the plurality of the first piston heads moves downward, at least one of the remaining first piston heads moves upward.

2. The stretching pad of a punching machine according to claim 1, characterized in that: The first piston head is used to divide the first cylinder into a first space and a second space from top to bottom, the second space contains a liquid medium, and a plurality of the second spaces are interconnected.

3. The stretching pad of a punching machine according to claim 1, characterized in that: The hydraulic cylinder also includes a first piston rod whose lower end is connected to the first piston head and whose upper end extends out of the first cylinder body. The lower ends of the plurality of support rods are respectively used to face the corresponding first piston rods.

4. The stretching pad of a punching machine according to claim 1, characterized in that: The punching machine comprises a workbench, the workbench is provided with a plurality of through holes, the blank holder is arranged at a position on the workbench opposite to the plurality of through holes, Wherein, the plurality of support rods are respectively hung in corresponding through holes and can move upward or downward along the through holes.

5. The stretch pad of a punching machine according to claim 4, characterized in that: The through hole is constructed as a stepped hole including a large diameter section and a small diameter section, wherein the large diameter section is located above the small diameter section, and the upper end of the support rod extends into the large diameter section and is provided with a large head section matching the shape of the large diameter section.

6. The stretch pad of a punching machine according to claim 1, characterized in that: The plurality of hydraulic cylinders are evenly distributed on the upper surface of the bearing portion, and the upper end of each of the hydraulic cylinders faces one of the support rods.

7. The stretch pad of a punching machine according to claim 1, characterized in that: The driving part includes a plurality of cylinders disposed at the lower side of the bearing part, and the cylinders are used to drive the bearing part to rise or fall.

8. The stretch pad of a punching machine according to claim 7, characterized in that: It also includes a plurality of adjustment devices arranged on the lower side of the bearing portion, and the adjustment devices include: Second cylinder block; a second piston head, disposed in the second cylinder; a second piston rod, one end of which is connected to the second piston head, and the other end of which extends upwardly out of the second cylinder body and is connected to the bearing portion; a limiting member, at least partially extending into the second cylinder body to limit the range of movement of the second piston head; and The adjusting part is used for adjusting the position of the limiting member in the second cylinder body.

9. The stretch pad of a punching machine according to claim 7, characterized in that: It also includes a plurality of locking devices for locking the bearing portion, the locking devices including: The third cylinder; a third piston head, disposed in the third cylinder body to divide the third cylinder body into a third space and a fourth space; A third piston rod, one end of which is connected to the third piston head, and the other end of which extends upwardly from the third cylinder body and is connected to the bearing portion; and An oil pipe is connected with the third space and the fourth space, and the oil pipe is provided with a valve.

10. A punching machine, characterized in that: A stretching pad for a punching machine comprising any one of claims 1-9.

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