A method of stamping a z-link with a saving die

Abstract

The present application relates to a kind of Z-shaped connecting rod stamping method and die of saving die surface, method steps include punch positioning hole, pre-punching, hole expansion and bending blanking.The die includes upper die and lower die, bending die includes the bending support block of lower die and the first bending punch and second bending punch of upper die, the upper surface of bending support block matches the lower surface structure of Z-shaped connecting rod and its feeding side is higher than discharge side, the lower end of first bending punch matches the upper structure of the corner of second plane portion and its two ends, and the lower end of second bending punch presses the upper surface of first plane portion;Blanking die includes the blanking support block of lower die and the blanking punch of upper die, blanking support block is equipped with the blanking hole matching the section structure of blanking punch;Bending die and blanking die have guide pin between upper die, guide pin matches the structure of second through hole.The setting mode of the present application makes two processing operations completed in one working step, so it saves die surface.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal stamping, in particular to a stamping method of Z-shaped connecting rod capable of saving die surface. BACKGROUND

[0002] Metal stamping is a common process for processing many metal products. With the diversification of customer demand, the design of the die also needs to meet various product requirements.

[0003] Figure 1 The product in the figure is a Z-shaped connecting rod 1, which includes a first planar part 11, a second planar part 12 and a third planar part 13 connected in Z shape in sequence, the second planar part 12 has a certain angle with the first planar part 11 and the third planar part 13, the first planar part 11 is in parallel relationship with the third planar part 13, the first planar part 11 has a first through hole 111 and a third through hole 112, and the third planar part 13 is provided with a second through hole 131. The first through hole 111 and the second through hole 131 are located at both ends of the Z-shaped connecting rod 1, and the hole walls of the first through hole 111 and the second through hole 131 and the edges of the first planar part 11 and the third planar part 13 all have relatively high bright band requirements (more than 90%). The third through hole 112 has a lower requirement.

[0004] Chinese patent CN115532943A discloses a forming method of a product with a large length-width ratio and a length-shortened forming die. The product produced by this die also has a Z-shaped structure and holes at both ends, but it is relatively slender. The design idea is to use a slender material strip as raw material, to rotate the circular hole in the strip-shaped preformed part by 90° after blanking, and then to perform operations such as hole expansion, hole flipping and bending, thereby reducing the length of the die. However, for the above-mentioned Z-shaped connecting rod 1, the product structure length size is not so long, and there is not so much length between adjacent stations, so setting a rotating device occupies the length of the die, and therefore it is not suitable.

[0005] Therefore, it is necessary to develop a new die and processing method to solve the above problems. SUMMARY

[0006] The main purpose of the present application is to provide a stamping method of Z-shaped connecting rod capable of saving die surface, which can complete bending and blanking operations in one station.

[0007] The present application achieves the above-mentioned purpose through the following technical scheme: a stamping method of Z-shaped connecting rod capable of saving die surface, the Z-shaped connecting rod including a first planar part, a second planar part and a third planar part connected in Z shape in sequence, the first planar part being provided with a first through hole, and the third planar part being provided with a second through hole.

[0008] The steps of the stamping method include:

[0009] S1, punch positioning hole: feed the material strip forward with the two sides of the material strip as positioning reference, the processing unit range of the material strip is strip-shaped and includes a connected area and a forming area connected at the head and tail, and a positioning hole is punched in the range of the connected area;

[0010] S2, pre-punching: punch a first process hole and a second process hole on the forming area with the two sides of the material strip and the positioning hole as reference, the position of the first process hole corresponds to the first through hole and the caliber of the first process hole is smaller than that of the first through hole, and the position of the second process hole corresponds to the second through hole and the caliber of the second process hole is smaller than that of the second through hole;

[0011] S3, hole expansion: expand the first process hole to the first through hole and expand the second process hole to the second through hole with the two sides of the material strip and the positioning hole as reference;

[0012] S4, bending and blanking: complete bending and blanking at the same station with the two sides of the material strip and the first through hole as reference, the bending is completed by a bending die which bends the forming area of a planar structure to form a first planar part, a second planar part and a third planar part, and the blanking is completed by a blanking die located at the feeding side of the bending die, which cuts off the connected area after the bending is completed.

[0013] Specifically, the material thickness of the Z-shaped connecting rod is greater than or equal to 1.5 mm, the waste material at the positioning hole is in dumbbell shape, and the connected area after the waste material is removed is in mouth-shaped structure with uniform front and rear edge width.

[0014] Further, the front and rear edge width of the mouth-shaped structure is 0.2-0.5 mm, and the left and right edge width is 1-1.5 mm.

[0015] Specifically, the pre-punching is divided into two steps, the first step obtains first process holes and second process holes with smaller caliber, and the second step refines the first process holes and the second process holes with larger caliber, and the refining width is 0.5-1 mm.

[0016] Another main object of the present application is to design a die to realize the above stamping method.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] The beneficial effects of the technical solution of this invention are:

[0022] 1. The configuration of this invention allows two processing operations to be completed in one step, thus saving mold surface area;

[0023] 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.

[0024] 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

[0025] Figure 1 A 3D view of the Z-shaped linkage;

[0026] Figure 2 This is a diagram showing the changes in the material strip;

[0027] Figure 3 This is a diagram showing the positional relationship between the strip material and the main components of the mold.

[0028] The numbers in the image represent:

[0029] 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;

[0030] 2-Material strip, 21-Connecting area, 211-Positioning hole, 22-Forming area, 221-First process hole, 222-Second process hole;

[0031] 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

[0032] The present invention will be further described in detail below with reference to specific embodiments.

[0033] Example:

[0034] like Figure 1As 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.

[0035] 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.

[0036] 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).

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] The stamping steps for Z-shaped connecting rod 1 are as follows:

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 method of stamping a Z-shaped link with a relief, the Z-shaped link comprising a first planar portion, a second planar portion and a third planar portion connected in series in a Z shape, the first planar portion having a first through hole formed therein, and the third planar portion having a second through hole formed therein; characterized in that The steps of the stamping method include: S1, punching a positioning hole: feeding the material strip forward with the two sides of the material strip as positioning reference, the processing unit range of the material strip is in a strip shape and includes a connecting area and a forming area connected at the ends, and a positioning hole is punched in the range of the connecting area; S2, pre-punching: punching a first process hole and a second process hole on the forming area with the two sides of the material strip and the positioning hole as reference, the position of the first process hole corresponds to the first through hole and the caliber of the first process hole is smaller than that of the first through hole, and the position of the second process hole corresponds to the second through hole and the caliber of the second process hole is smaller than that of the second through hole; S3, hole expansion: expanding the first process hole to the first through hole and the second process hole to the second through hole with the two sides of the material strip and the positioning hole as reference; S4, bending and blanking: completing bending and blanking at the same station with the two sides of the material strip and the first through hole as reference, the bending is completed by a bending die which bends the forming area of a planar structure to form a first planar part, a second planar part and a third planar part, and the blanking is completed by a blanking die located at the feeding side of the bending die, the blanking die cuts off the connecting area after the bending is completed.

2. The method of claim 1, wherein: The thickness of the Z-shaped connecting rod is greater than or equal to 1.5 mm, the waste material at the positioning hole is in a dumbbell shape, and the connecting area after the waste material is removed is in a mouth-shaped structure with uniform front and rear edge widths.

3. The method of claim 2, wherein: The front and rear edge widths of the mouth-shaped structure are 0.2-0.5 mm, and the left and right edge widths are 1-1.5 mm.

4. The method of claim 1, wherein: The pre-punching is divided into two steps, the first step obtains first and second process holes with smaller calibers, and the second step refines the first and second process holes to have larger calibers, and the refining width is 0.5-1 mm.

5. A die for use in carrying out the method of any one of claims 1 to 4, comprising an upper die and a lower die, characterised in that: The bending die includes a bending support block located at the lower die and first and second bending punches located at the upper die, the upper surface of the bending support block matches the lower surface structure of the Z-shaped connecting rod and the feeding side is higher than the discharging side, the lower end of the first bending punch matches the upper structure of the second planar part and the corners at the two ends thereof, and the lower end of the second bending punch presses the upper surface of the first planar part; the blanking die includes a blanking support block located at the lower die and a blanking punch located at the upper die, the blanking support block is provided with a blanking hole matching the cross-sectional structure of the blanking punch; the bending die and the blanking die have a guide pin located at the upper die, and the guide pin matches the structure of the second through hole.

6. The mold of claim 5, wherein: The cross section of the blanking punch is in a dumbbell shape, the lower projection range of the blanking punch covers the range of the connecting area, and the two sides of the blanking punch are wider than the connecting area.

7. The mold of claim 5, wherein: The reaming step is completed by a reaming die, which comprises a reaming support plate on the lower die and a third guide rod on the upper die, the third guide rod matching the positioning hole in section structure, the reaming support plate being provided with a limiting groove, a first conical frustum and a second conical frustum, the limiting groove being located in the middle of the reaming support plate and matching the third guide rod, the first conical frustum being located on the discharging side of the limiting groove and used for expanding the first process hole into the first through hole, and the second conical frustum being located on the feeding side of the limiting groove and used for expanding the second process hole into the second through hole.

8. The mold of claim 5, wherein: The upper die is sequentially provided with a positioning hole punch, a second pre-cut punch, a first pre-cut punch, a first guide rod, a second fine-cut punch, a hole cutting punch, a first fine-cut punch and a second guide rod, and the lower die is sequentially provided with a positioning waste discharge support block, a pre-cut support block, a first fine-cut support block and a second fine-cut support block, the positioning hole punch and the second pre-cut punch being located above the positioning waste discharge support block, the first pre-cut punch being opposite to the pre-cut support block, the first pre-cut punch and the second fine-cut punch being adjacent to the first guide rod, the second fine-cut punch being opposite to the first fine-cut support block, the hole cutting punch and the first fine-cut punch being located above the second fine-cut support block, and the second guide rod being adjacent to the first fine-cut punch.

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