Stamping method of Z-shaped connecting rod capable of saving die surface

Abstract

The invention relates to a stamping method and die for a Z-shaped connecting rod capable of saving a die surface. The method comprises the steps of positioning hole punching, pre-punching, chambering and bending blanking. The die comprises an upper die and a lower die, the bending die comprises a bending supporting block located on the lower die, a first bending punch and a second bending punch, the first bending punch and the second bending punch are located on the upper die, the upper surface of the bending supporting block is matched with the lower surface structure of the Z-shaped connecting rod, the feeding side of the bending supporting block is higher than the discharging side, and the lower end of the first bending punch is matched with a second plane part and corner upper structures at the two ends of the second plane part. The lower end of the second bending punch presses the upper surface of the first plane part; the blanking die comprises a blanking supporting block located on the lower die and a blanking punch located on the upper die, and a blanking hole matched with the cross section structure of the blanking punch is formed in the blanking supporting block. A guide pin located on the upper die is arranged between the bending die and the blanking die, and the guide pin is matched with the structure of the second through hole. According to the arrangement mode, two machining operations are completed in one working step, so that a die surface is saved.

Description

Technical Field

[0001] This invention relates to the field of metal stamping technology, and in particular to a stamping method for a Z-shaped connecting rod that saves die surface area. Background Technology

[0002] Metal stamping is a common process in the processing of many metal products. With the diversification of customer needs, mold design must also meet the requirements of various products.

[0003] Figure 1 The product in question is a Z-shaped connecting rod 1, which includes a first planar portion 11, a second planar portion 12, and a third planar portion 13 connected in a Z-shape. The second planar portion 12 has an included angle with both the first and third planar portions 11 and 13. The first and third planar portions 11 and 13 are parallel to each other. The first planar portion 11 has a first through hole 111 and a third through hole 112, and the third planar portion 13 has a second through hole 131. The first and second through holes 111 and 131 are located at approximately both ends of the Z-shaped connecting rod 1. The walls of the first and second through holes 111 and 131, as well as the edges of the first and third planar portions 11 and 13, have a relatively high requirement for a bright band (above 90%). The requirement for the third through hole 112 is lower.

[0004] Chinese patent CN115532943A discloses a molding method for products with large length-to-width ratios and a molding die for shortening the length. The products produced by this die also have a Z-shaped structure and holes at both ends, but are relatively long and slender. The design concept uses a long, thin strip of material as raw material. After the strip-shaped pre-formed part is blanked, it is rotated 90° using the circular holes within it, and then operations such as hole enlargement, hole turning, and bending are performed, thereby reducing the length of the die. However, for the aforementioned Z-shaped connecting rod 1, the product structure length is not that long, and the distance between adjacent workstations is not that large. Setting up a rotating device would actually increase the die length, so it is not suitable.

[0005] Therefore, it is necessary to develop a new mold and processing method to solve the above problems. Summary of the Invention

[0006] The main objective of this invention is to provide a stamping method for Z-shaped connecting rods that saves die surface area, enabling bending and blanking operations to be completed sequentially in one station, thus saving die surface area.

[0007] The present invention achieves the above objective through the following technical solution: a stamping method for a Z-shaped connecting rod that saves die surface, the Z-shaped connecting rod comprising a first planar portion, a second planar portion and a third planar portion connected in a Z-shape in sequence, the first planar portion having a first through hole, and the third planar portion having a second through hole; The steps of the stamping method include: S1. Punching positioning holes: The material strip is conveyed forward using both sides as positioning references. The processing unit range of the material strip is strip-shaped and includes a connecting area and a forming area connected end to end. Positioning holes are punched within the area of ​​the connecting area. S2. Pre-punching: Taking the two sides of the strip and the positioning hole as reference, punch out the first process hole and the second process hole in the forming area. The position of the first process hole corresponds to the first through hole and the diameter of the first process hole is smaller than that of the first through hole. The position of the second process hole corresponds to the second through hole and the diameter of the second process hole is smaller than that of the second through hole. S3. Enlarging the hole: Taking the two sides of the strip and the positioning hole as reference, the first process hole is enlarged into the first through hole and the second process hole is enlarged into the second through hole; S4. Bending and blanking: Using the two sides of the strip and the first through hole as references, bending and blanking are completed at the same station. Bending is completed by bending die. The bending die bends the forming area of ​​the planar structure to form a first planar part, a second planar part and a third planar part. Blanking is completed by blanking die located on the feeding side of the bending die. The blanking die cuts off the connecting area only after bending is completed.

[0008] Specifically, the Z-shaped connecting rod has a material thickness of ≥1.5mm, the waste material at the positioning hole has a dumbbell-shaped structure, and the connecting area after removing the waste material has a square-shaped structure with uniform width at the front and rear edges.

[0009] Furthermore, the width of the front and rear edges of the square structure is 0.2~0.5mm, and the width of the left and right edges is 1~1.5mm.

[0010] Specifically, the pre-punching process is divided into two steps. The first step produces a first process hole and a second process hole with a smaller diameter. The second step refines the first process hole and the second process hole with a larger diameter, and the refinement width is 0.5~1mm.

[0011] Another main objective of this invention is to design a mold to realize the above stamping method.

[0012] The present invention achieves the above-mentioned objective through the following technical solution: a die for performing the above stamping method includes an upper die and a lower die. The bending die includes a bending support block located in the lower die and a first bending punch and a second bending punch located in the upper die. The upper surface of the bending support block matches the lower surface structure of the Z-shaped connecting rod, and its feeding side is higher than its discharging side. The lower end of the first bending punch matches the second flat portion and the upper corner structure at both ends. The lower end of the second bending punch presses against the upper surface of the first flat portion. The blanking die includes a blanking support block located in the lower die and a blanking punch located in the upper die. The blanking support block is provided with a blanking hole that matches the cross-sectional structure of the blanking punch. A guide pin located in the upper die is provided between the bending die and the blanking die. The guide pin matches the structure of the second through hole.

[0013] Specifically, the blanking punch has a dumbbell-shaped cross-section, the lower projection range of the blanking punch covers the range of the connecting area, and both sides of the blanking punch are wider than the connecting area.

[0014] Specifically, the hole enlargement step is completed using a hole enlargement mold. The hole enlargement mold includes a hole enlargement support plate located in the lower mold and a third guide rod located in the upper mold. The cross-sectional structure of the third guide rod matches the positioning hole. The hole enlargement support plate is provided with a limiting groove, a first cone, and a second cone. The limiting groove is located in the middle of the hole enlargement support plate and matches the third guide rod. The first cone is located on the discharge side of the limiting groove and is used to enlarge the first process hole into the first through hole. The second cone is located on the feed side of the limiting groove and is used to enlarge the second process hole into the second through hole.

[0015] Specifically, the upper die is sequentially provided with a positioning hole punch, a second pre-cutting punch, a first pre-cutting punch, a first guide rod, a second precision cutting punch, a hole-cutting punch, a first precision cutting punch, and a second guide rod. The lower die is sequentially provided with a positioning waste removal block, a pre-cutting block, a first precision cutting block, and a second precision cutting block. The positioning hole punch and the second pre-cutting punch are located above the positioning waste removal block. The first pre-cutting punch is opposite to the pre-cutting block. The first pre-cutting punch and the second precision cutting punch are adjacent to the first guide rod. The second precision cutting punch is opposite to the first precision cutting block. The hole-cutting punch and the first precision cutting punch are located above the second precision cutting block. The second guide rod is adjacent to the first precision cutting punch.

[0016] The beneficial effects of the technical solution of this invention are: 1. The configuration of this invention allows two processing operations to be completed in one step, thus saving mold surface area; 2. This is to ensure that the front and rear positioning areas of the positioning holes provide only a small machining allowance, which facilitates the flow of materials and thus ensures a high proportion of bright bands on the front and rear edges of the product. 3. Both process holes are made by first cutting a small hole and then a large hole. This is because the first stage of the pre-punching step is to break the material in the middle and reduce the pulling effect. The second stage is to refine the hole wall. Based on the first stage, the tearing of the material can be reduced, thereby increasing the ratio of the bright band on the inner wall of the first through hole and the second through hole. Attached Figure Description

[0017] Figure 1 A three-dimensional view of the Z-shaped linkage; Figure 2 This is a diagram showing the changes in the material strip; Figure 3 This is a diagram showing the positional relationship between the strip material and the main components of the mold.

[0018] The numbers in the image represent: 1-Z-shaped connecting rod, 11-first planar part, 111-first through hole, 112-third through hole, 12-second planar part, 13-third planar part, 131-second through hole; 2-Material strip, 21-Connecting area, 211-Positioning hole, 22-Forming area, 221-First process hole, 222-Second process hole; 31a-Positioning punch, 31b-Second pre-cutting punch, 31c-First pre-cutting punch, 31d-Second precision cutting punch, 31e-Drilling punch, 31f-First precision cutting punch, 31g-Blanking punch, 32a-Positioning waste removal block, 32b-Pre-cutting block, 32c-First precision cutting block, 32d-Second precision cutting block, 32e-Blanking block, 32f-Bending block, 33a-First guide rod, 33b-Second guide rod, 33c-Third guide rod, 34-Enlarging block, 341-Limiting groove, 342-First cone, 343-Second cone, 35-Guide pin, 36a-First bending punch, 36b-Second bending punch. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments.

[0020] Example: like Figure 1 As shown, the Z-shaped connecting rod 1 includes a first flat portion 11, a second flat portion 12, and a third flat portion 13 connected in a Z-shape in sequence. The first flat portion 11 has a first through hole 111 and a third through hole 112, and the third flat portion 13 has a second through hole 131. The material thickness of the Z-shaped connecting rod 1 is ≥1.5mm.

[0021] The present invention provides a mold comprising an upper mold and a lower mold. The upper mold is provided with, in sequence, a positioning hole punch 31a, a second pre-cutting punch 31b, a first pre-cutting punch 31c, a first guide rod 33a, a second precision cutting punch 31d, a hole-cutting punch 31e, a first precision cutting punch 31f, a second guide rod 33b, a third guide rod 33c, a blanking punch 31g, a guide pin 35, a first bending punch 36a, and a second bending punch 36b. The lower mold is provided with, in sequence, a positioning waste removal support block 32a, a pre-cutting support block 32b, a first precision cutting support block 32c, a second precision cutting support block 32d, a hole-expanding support block 34, a blanking support block 32e, and a bending support block 32f.

[0022] The positioning punch 31a is used to punch out the positioning hole 211. The first guide rod 33a, the second guide rod 33b, and the third guide rod 33c all use the positioning hole 211 to position the strip 2. The second pre-cutting punch 31b is used to punch out the smaller second process hole 222, and the second precision cutting punch 31d is used to punch out the larger second process hole 222 (by increasing the punching range). The first pre-punching punch 31c is used to punch out the smaller first process hole 221, and the first precision cutting punch 31f is used to punch out the larger first process hole 221 (by increasing the punching range). The hole enlarging block 34 is used to enlarge the first process hole 221 into the first through hole 111 and the second process hole 222 into the second through hole 131 (by expanding). The hole cutting punch 31e is used to punch out the third through hole 112 (the presence or absence of the third through hole 112 does not affect the implementation of the process).

[0023] like Figure 3 As shown, the positioning punch 31a and the second pre-cutting punch 31b are located above the positioning waste removal block 32a. The first pre-cutting punch 31c is opposite to the pre-cutting block 32b. The first pre-cutting punch 31c and the second precision cutting punch 31d are adjacent to the first guide rod 33a. The second precision cutting punch 31d is opposite to the first precision cutting block 32c. The hole cutting punch 31e and the first precision cutting punch 31f are located above the second precision cutting block 32d. The second guide rod 33b is adjacent to the first precision cutting punch 31f.

[0024] The positioning hole punch 31a and the front half of the positioning waste removal block 32a belong to the positioning hole punching station, used to complete the positioning hole punching step; the second pre-cutting punch 31b, the rear half of the positioning waste removal block 32a, the second pre-cutting punch 31b, the first pre-cutting punch 31c, and the pre-cutting block 32b belong to the pre-punching station, used to complete the first stage of the pre-punching step; the first guide rod 33a, the second precision cutting punch 31d, the hole cutting punch 31e, and the first precision cutting punch 32a belong to the pre-punching station, used to complete the first stage of the pre-punching step; 1f, the first precision cutting support block 32c and the second precision cutting support block 32d belong to the precision cutting station, used to complete the second stage of the pre-punching step; the third guide rod 33c and the reaming support block 34 belong to the reaming station (occupying two steps), used to complete the reaming step; the blanking punch 31g, the guide pin 35, the first bending punch 36a, the second bending punch 36b, the blanking support block 32e and the bending support block 32f belong to the bending blanking station, used to complete the bending blanking step. Because the position of the punching positioning hole 211 is very close to the pre-cutting position of the second process hole 222, the positioning waste removal support block 32a is shared by the punching positioning hole station and the pre-punching station. The reason for dividing the pre-punching step into two stages is to improve the brightness of the first through hole 111 and the second through hole 131. Because the first stage can leave a very small machining allowance, the inner wall of the process hole will not produce a large pulling effect, and the tearing range can be reduced.

[0025] like Figure 3 As shown, the hole enlargement step is completed using a hole enlargement mold. The hole enlargement mold includes a hole enlargement support block 34 located in the lower mold and a third guide rod 33c located in the upper mold. The cross-sectional structure of the third guide rod 33c matches the positioning hole 211. The hole enlargement support block 34 is provided with a limiting groove 341, a first cone 342 and a second cone 343. The limiting groove 341 is located in the middle of the hole enlargement support block 34 and matches the third guide rod 33c. The first cone 342 is located on the discharge side of the limiting groove 341 and is used to enlarge the first process hole 221 into a first through hole 111. The second cone 343 is located on the feed side of the limiting groove 341 and is used to enlarge the second process hole 222 into a second through hole 131.

[0026] Because the first process hole 221 in the previous step and the second process hole 222 in the next step are very close and separated only by a third guide rod 33c, the reaming block 34 spans two steps and can improve positioning accuracy using the third guide rod 33c. The first cone 342 is used to ream the first process hole 221, and the second cone 343 is used to ream the second process hole 222.

[0027] The stamping steps for Z-shaped connecting rod 1 are as follows: S1. Punching Positioning Holes: Using both sides of the material strip 2 as positioning references, the material strip 2 is conveyed forward. The processing unit of the material strip 2 is strip-shaped and includes a connecting area 21 and a forming area 22 connected end to end. Positioning holes 211 are punched within the connecting area 21. The waste material at the positioning hole 211 has a dumbbell-shaped structure (corresponding to the cross-sectional shape of the positioning hole punch 31a). After the waste material is removed, the connecting area 21 has a U-shaped structure with uniform width at the front and rear edges. The width of the front and rear edges of the U-shaped structure is 0.2~0.5mm, and the width of the left and right edges is 1~1.5mm.

[0028] Because the connecting area 21 and the forming area 22 are spaced apart and the material strip 2 has a relatively long and thin structure, only one positioning hole 211 is provided on the connecting area 21. However, the positioning hole 211 does not adopt a conventional round hole structure. This is to ensure that the positioning areas 21 in front of and behind the positioning hole 211 only provide a small machining allowance (the hole enlargement step will cause the material in the forming area 22 to be squeezed into the positioning area 21), which facilitates the flow of material and thus ensures a high proportion of bright strips on the front and rear edges of the product. Because the front and rear edges of the Z-shaped connecting rod 1 in the embodiment are arc-shaped, the front and rear edges of the positioning area 21 must also be arc-shaped and have a small width. However, the left and right edges of the positioning area 21 need to provide the tension connecting the two forming areas 22, so the width of the left and right edges needs to be relatively large.

[0029] S2. Pre-punching: Based on the two sides of the strip 2 and the positioning hole 211, punch out the first process hole 221 and the second process hole 222 on the forming area 22. The position of the first process hole 221 corresponds to the first through hole and the diameter of the first process hole 221 is smaller than that of the first through hole 111. The position of the second process hole 222 corresponds to the second through hole 131 and the diameter of the second process hole 222 is smaller than that of the second through hole 131.

[0030] The first process hole 221 is a pre-formed structure of the first through hole 111, and the second process hole 222 is a pre-formed structure of the second through hole 131. If the material thickness is not large, then only one punching is needed. However, in this embodiment, the material thickness is greater than 1.5mm, which is considered thick material and is more likely to produce larger tear bands. Therefore, in order to increase the proportion of bright bands on the inner walls of the first through hole 111 and the second through hole 131, both process holes are first cut with a small hole and then with a large hole. This is because the first stage of the pre-punching step is to break the material in the middle to reduce the pulling effect, and the second stage is to refine the hole wall. Based on the first stage, the tearing of the material can be reduced. Therefore, in this embodiment, the pre-punching is divided into two steps. The first step obtains the first and second process holes with smaller diameters, and the second step refines them to obtain the first and second process holes with larger diameters. The refinement width is 0.5~1mm.

[0031] S3. Enlarging the hole: Taking the two sides of the strip 2 and the positioning hole 211 as the reference, the first process hole 221 is enlarged into the first through hole 111 and the second process hole 222 is enlarged into the second through hole 131.

[0032] The process hole is designed to be slightly smaller than the through hole (0.1~0.5mm). Therefore, in order to obtain a precise through hole, the diameter of the process hole will be appropriately increased by enlarging the hole to obtain the final hole diameter. During this process, the material around the first through hole 111 and the second through hole 131 will inevitably be squeezed outward. Since the positioning hole 211 is already U-shaped, it is conducive to the flow of material.

[0033] S4. Bending and blanking: Using the two sides of the strip 2 and the second through hole 131 as references, bending and blanking are completed at the same station. Bending is completed by bending die. The bending die bends the forming area 22 of the planar structure to form the first planar part 11, the second planar part 12 and the third planar part 13. Blanking is completed by blanking die located on the feeding side of bending die. The blanking die cuts off the connecting area 21 only after bending is completed.

[0034] like Figure 3 As shown, the bending die includes a bending support block 32f located in the lower die and a first bending punch 36a and a second bending punch 36b located in the upper die. The upper surface of the bending support block 32f matches the lower surface structure of the Z-shaped connecting rod 1, and its feeding side is higher than the discharge side. The lower end of the first bending punch 36a matches the second flat part 12 and the upper corner structure at both ends. The lower end of the second bending punch 36b presses against the upper surface of the first flat part 11. The blanking die includes a blanking support block 32e located in the lower die and a blanking punch 31g located in the upper die. The blanking support block 32e is provided with a blanking hole (which is blocked) that matches the cross-sectional structure of the blanking punch 31g. There is a guide pin 35 located in the upper die between the bending die and the blanking die. The guide pin 35 matches the structure of the second through hole 131.

[0035] Although the blanking die appears to come first and the bending die second in terms of mold structure, in terms of process, bending comes first and blanking comes second. After the Z-shaped connecting rod 1 is bent at the end of the strip 2, the blanking die cuts off the connecting area 21 in the same step, and the forming area 22 becomes an independent Z-shaped connecting rod 1. Blanking targets the material on the feeding side of the third plane portion 13 (i.e., the connecting area 21), while bending targets the second plane portion 12 and the first plane portion 11 (located on the discharge side of the third plane portion 13 during processing). Therefore, the third plane portion 13 remains stationary during this process. Thus, both operations are performed by positioning the strip through the cooperation of the guide pin 35 and the second through hole 131. Because this product is inherently a thick material, the springback after mold closing is small, and no further shaping is needed to meet the requirements, making this design of immediately blanking after bending possible. This setup allows two processing operations to be completed in one step, thus saving mold surface area. During the bending process, the end of the strip 2, which is still in a planar state, extends above the bending support block 32f. The first bending punch 36a is used to obtain the bending angle between the third planar portion 13 and the second planar portion 12, and the second bending punch 36b is used to obtain the bending angle between the second planar portion 12 and the first planar portion 11. Therefore, in the mold, the Z-shaped connecting rod 1 is positioned with the third planar portion 13 facing the feeding side and the first planar portion 11 facing the discharge side. Because the bending support block 32f is higher on the feeding side than on the discharge side, when the mold opens, the Z-shaped connecting rod 1 can only slide down in the lower discharge direction and will not move in the higher feeding direction. Even if the Z-shaped connecting rod 1 initially stops in place, it will push the previously formed Z-shaped connecting rod 1 backward as the strip 2 continues to be conveyed, ensuring that it slides out of the stamping area of ​​the mold and avoids mold collision.

[0036] like Figure 3 As shown, the cross-section of the blanking punch 31g is dumbbell-shaped, the lower projection range of the blanking punch 31g covers the range of the connecting area 21, and both sides of the blanking punch 31g are wider than the connecting area 21.

[0037] The widened design of the blanking punch 31g ensures that the connecting area 21 is completely removed, and that the complete Z-shaped connecting rod 1 is separated.

[0038] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A stamping method for a Z-shaped connecting rod that saves die surface area, the Z-shaped connecting rod comprising a first planar portion, a second planar portion, and a third planar portion connected in a Z-shape in sequence, the first planar portion having a first through hole, and the third planar portion having a second through hole; characterized in that The steps of the stamping method include: S1. Punching positioning holes: The material strip is conveyed forward using both sides as positioning references. The processing unit range of the material strip is strip-shaped and includes a connecting area and a forming area connected end to end. Positioning holes are punched within the area of ​​the connecting area. S2. Pre-punching: Taking the two sides of the strip and the positioning hole as reference, punch out the first process hole and the second process hole in the forming area. The position of the first process hole corresponds to the first through hole and the diameter of the first process hole is smaller than that of the first through hole. The position of the second process hole corresponds to the second through hole and the diameter of the second process hole is smaller than that of the second through hole. S3. Enlarging the hole: Taking the two sides of the strip and the positioning hole as reference, the first process hole is enlarged into the first through hole and the second process hole is enlarged into the second through hole; S4. Bending and blanking: Using the two sides of the strip and the first through hole as references, bending and blanking are completed at the same station. Bending is completed by bending die. The bending die bends the forming area of ​​the planar structure to form a first planar part, a second planar part and a third planar part. Blanking is completed by blanking die located on the feeding side of the bending die. The blanking die cuts off the connecting area only after bending is completed.

2. The stamping method for the Z-shaped connecting rod with a saving die surface according to claim 1, characterized in that: The Z-shaped connecting rod has a material thickness of ≥1.5mm, the waste material at the positioning hole has a dumbbell-shaped structure, and the connecting area after removing the waste material has a square-shaped structure with uniform width at the front and rear edges.

3. The stamping method for the Z-shaped connecting rod with a saving die surface according to claim 2, characterized in that: The width of the front and rear edges of the square structure is 0.2~0.5mm, and the width of the left and right edges is 1~1.5mm.

4. The stamping method for the Z-shaped connecting rod with a saving die surface according to claim 1, characterized in that: The pre-punching process is divided into two steps. The first step produces a first process hole and a second process hole with a smaller diameter. The second step refines the first process hole and the second process hole with a larger diameter, and the refinement width is 0.5~1mm.

5. A die for performing any of the stamping methods of claims 1-4, comprising an upper die and a lower die, characterized in that: The bending die includes a bending support block located in the lower die and a first bending punch and a second bending punch located in the upper die. The upper surface of the bending support block matches the lower surface structure of the Z-shaped connecting rod, and its feed side is higher than its discharge side. The lower end of the first bending punch matches the second flat portion and the upper corner structure at both ends. The lower end of the second bending punch presses against the upper surface of the first flat portion. The blanking die includes a blanking support block located in the lower die and a blanking punch located in the upper die. The blanking support block is provided with a blanking hole that matches the cross-sectional structure of the blanking punch. A guide pin located in the upper die is provided between the bending die and the blanking die. The guide pin matches the structure of the second through hole.

6. The mold according to claim 5, characterized in that: The blanking punch has a dumbbell-shaped cross-section, and its lower projection covers the area of ​​the connecting region, with both sides of the blanking punch extending beyond the connecting region.

7. The mold according to claim 5, characterized in that: The hole enlargement step is completed using a hole enlargement mold. The hole enlargement mold includes a hole enlargement support plate located in the lower mold and a third guide rod located in the upper mold. The cross-sectional structure of the third guide rod matches the positioning hole. The hole enlargement support plate is provided with a limiting groove, a first cone, and a second cone. The limiting groove is located in the middle of the hole enlargement support plate and matches the third guide rod. The first cone is located on the discharge side of the limiting groove and is used to enlarge the first process hole into the first through hole. The second cone is located on the feed side of the limiting groove and is used to enlarge the second process hole into the second through hole.

8. The mold according to claim 5, characterized in that: The upper die is sequentially provided with a positioning hole punch, a second pre-cutting punch, a first pre-cutting punch, a first guide rod, a second precision cutting punch, a hole-cutting punch, a first precision cutting punch, and a second guide rod. The lower die is sequentially provided with a positioning waste removal block, a pre-cutting block, a first precision cutting block, and a second precision cutting block. The positioning hole punch and the second pre-cutting punch are located above the positioning waste removal block. The first pre-cutting punch is opposite to the pre-cutting block. The first pre-cutting punch and the second precision cutting punch are adjacent to the first guide rod. The second precision cutting punch is opposite to the first precision cutting block. The hole-cutting punch and the first precision cutting punch are located above the second precision cutting block. The second guide rod is adjacent to the first precision cutting punch.

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