Punch for hole-punching equipment

Abstract

The goal is to prevent, as much as possible, situations where the inner diameter of a hole formed by punching becomes larger at the end of the punching process compared to the start, thereby improving the shape accuracy of the hole without reducing productivity. [Solution] This punch 1 for a hole-punching device is a punch used in a hole-punching device 5 for forming a hole 3 in a metal plate 2 by punching, and the punch 1 has an annular blade portion 7 that is pointed towards the tip, and the inner diameter of the blade portion 7 increases from the base end side to the tip side of the blade portion 7.

Description

Technical Field

[0001] The present invention relates to a punch for a hole drilling device.

Background Art

[0002] Conventionally, as hole drilling in manufacturing processes, machining with a drill has been common. However, in recent years, in view of the ability to form a plurality of holes at once, punching, which is a type of press working using a punch, is becoming the mainstream (for example, refer to Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the other hand, when performing punching with excellent productivity, the accuracy of the holes can be a problem. That is, punching is a type of press working using shear, and it is desirable that the entire inner peripheral surface of the hole formed by this working is a shear surface. However, in reality, when the tip corner of the punch and the end face on the punching end side of the plate to be processed shrink to a certain distance during shearing, a break occurs between the tip corner and the end face. Therefore, a fracture surface of a corresponding size occurs on the punching end side of the inner peripheral surface of the hole, and there is a problem that the inner diameter dimension of the hole becomes larger on the punching end side than on the punching start side.

[0005] In view of the above circumstances, in this specification, the technical problem to be solved is to prevent as much as possible the situation where the inner diameter dimension of the hole formed by punching becomes larger on the punching end side than on the punching start side, and to improve the shape accuracy of the hole without reducing productivity.

Means for Solving the Problems

[0006] The aforementioned problem is solved by the punch for a hole-punching device according to the present invention. Specifically, this punch is used in a hole-punching device for forming holes in a metal plate by punching, and the punch is characterized by having an annular cutting edge that is pointed toward the tip, and the inner diameter of the cutting edge increases from the base end toward the tip.

[0007] The punch according to the present invention is provided with a blade that is pointed towards the tip, and the inner diameter of this blade is shaped to increase from the base end to the tip. When punching holes using this punch, the blade at the tip of the punch bites into the metal plate during punching, making the force generated on the outside of the blade smaller than the force generated on the inside of the blade in the metal plate. As a result, the deformation that occurs on the outside of the blade in the metal plate when the blade bites in is relatively reduced, and the shape accuracy of the inner surface of the hole formed on the outside of the blade can be improved. Furthermore, in the punch according to the present invention, the blade with the above shape is formed in an annular shape. As a result, the way the blade bites in can be made uniform around the entire circumference, so that the stress distribution generated on the outside of the blade due to this biting can be kept uniform around the entire circumference. Therefore, with this configuration, it is possible to form the inner surface of the hole with high accuracy around the entire circumference.

[0008] Furthermore, in the punch for a hole-punching apparatus according to the present invention, the outer diameter of the blade portion may be constant.

[0009] By defining the blade shape in this way, deformation that occurs on the outside of the area where the blade bites during punching can be minimized. Therefore, it becomes possible to further improve the accuracy of the hole shape by making the inner surface of the hole as sheared as possible (in other words, by minimizing the generation of fracture surfaces). [Effects of the Invention]

[0010] As described above, the punch for a hole-punching apparatus according to the present invention makes it possible to prevent as much as possible the situation in which the inner diameter of the hole formed by punching becomes larger at the end of punching compared to the start of punching, thereby improving the shape accuracy of the hole without reducing productivity. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing an overview of a hole-punching process using a punch for a hole-punching apparatus according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the state after the punch has been lowered from the state shown in Figure 1, and the cutting edge at the tip has been driven into the metal plate. [Figure 3] This is a cross-sectional view showing the state after the punch has been further lowered from the state shown in Figure 2 to punch out the metal plate. [Modes for carrying out the invention]

[0012] The details of a punch for a hole-punching device according to one embodiment of the present invention will be described below based on the drawings.

[0013] Figure 1 shows an overview of a hole-punching process using a punch 1 for a hole-punching device according to one embodiment of the present invention. This hole-punching process involves moving a punch 1 for a hole-punching device (hereinafter simply referred to as punch 1), which has a predetermined shape, along the thickness direction (vertical direction in Figure 1) of the metal plate 2 to be punched, and punching out the metal plate 2 with the punch 1 by shear, thereby forming a hole 3 in the metal plate 2. This can be carried out by a hole-punching device 5 that includes a punch 1, a die 4 that supports the metal plate 2, and a drive device (not shown) that drives the punch 1. In this embodiment, the die 4 is provided with an insertion hole 6 through which the punch 1 can be inserted, and by moving (descending) the punch 1 to a position where at least the tip of the punch 1 is inserted into the insertion hole 6 of the die 4, a hole 3 can be formed in the metal plate 2.

[0014] The punch 1 is columnar in shape overall, and has a pointed blade portion 7 at its tip. Here, "pointed shape" refers to a shape in which the thickness dimension of the blade portion 7 decreases from the base end to the tip end. When the tip of the punch 1 is viewed from a direction along its axis X (stroke direction), the blade portion 7 having the above shape forms an annular shape. In this case, the cross-sectional shape of the blade portion 7 obtained by cutting with a virtual cross-section including axis X is the same as the shape in Figure 1, regardless of the orientation of the virtual cross-section.

[0015] The inner diameter dimension d1 of the blade portion 7, that is, the radial dimension of the inner circumferential surface 7a of the blade portion 7, increases from the base end to the tip end of the blade portion 7. On the other hand, the outer diameter dimension d2 of the blade portion 7, that is, the radial dimension of the outer circumferential surface 7b of the blade portion 7, remains constant regardless of its position along the axis X of the blade portion 7.

[0016] In this embodiment, the inner circumferential surface 7a of the blade portion 7 has a tapered shape, and the inner diameter dimension d1 of the blade portion 7 increases at a constant rate from the base end to the tip end. In addition, in this embodiment, a through hole 8 is provided in the center of the punch 1, passing through the punch 1 in a direction along the axis X.

[0017] The taper angle θ of the inner circumferential surface 7a is, in principle, arbitrary and can be set appropriately within the range of 10° to 80°, preferably within the range of 10° to 45°.

[0018] The dimensions of the blade portion 7 in the orientation along the axis X can be set to any size as long as it is possible to form a hole 3 in the target metal plate 2 by punching. However, if it is too small compared to the thickness dimension of the metal plate 2, the purpose of providing the blade portion 7 may be lost. For example, it is best to set it to 50% or more of the thickness dimension of the target metal plate 2.

[0019] Next, an example of drilling using the drilling apparatus 5 with the above configuration will be explained based on Figures 1 to 3.

[0020] First, as shown in FIG. 1, with the metal plate 2 to be processed placed at a predetermined position on the die 4, the punch 1 is arranged at a predetermined position on the opposite side of the die 4 through the metal plate 2 (in FIG. 1, it is the upper position of the metal plate 2). In this case, the punch 1 is arranged in a posture where the tip of the punch 1 is directed toward the metal plate 2.

[0021] Then, the movement of the punch 1 toward the die 4 is started, and the annular blade portion 7 provided at the tip of the punch 1 is pressed against and penetrated into a predetermined position of the metal plate 2, that is, the planned position for forming the hole 3 (see FIG. 2). As the punch 1 is pushed in (the blade portion 7 penetrates), the metal plate 2 is divided into a portion located outside the blade portion 7 (outer portion 2a) and a portion located inside the blade portion 7 (inner portion 2b). Also, on the inner circumference of the blade portion 7, a tapered inner circumferential surface 7a is provided whose radial dimension decreases from the tip side toward the base end side. Therefore, as the blade portion 7 is pushed in, a larger pushing force and shearing force act on the inner portion 2b than on the outer portion 2a which is a part of the metal plate 2 body. As a result, during the punching process, relatively large deformation occurs in the inner portion 2b, while the deformation occurring in the outer portion 2a is relatively small and suppressed. In this way, the punching process of the inner portion 2b is performed, and the hole 3 is formed in the metal plate 2 by this punching (see FIG. 3).

[0022] After forming the hole 3 in this way, for example, although not shown in the figure, a pressurized fluid such as compressed air is discharged into the inner circumference of the blade portion 7 through the through hole 8 of the punch 1 to push out the inner portion 2b in a state of penetrating into the inner side of the blade portion 7. Thereby, the inner portion 2b which becomes the scrap portion is discharged through the insertion hole 6.

[0023] Note that the discharging means for the inner portion 2b is not limited to this. For example, although not shown in the figure, a pin may be inserted into the through hole 8 from the base end side to push out the inner portion 2b that has penetrated into the blade portion 7, thereby discharging the inner portion 2b from the die 4. Alternatively, with the insertion hole 6 blocked, the inside of the through hole 8 is set in a decompressed state, and the inner portion 2b is drawn toward the through hole 8 side to discharge the inner portion 2b.

[0024] As described above, the punch 1 for the hole-punching device 5 according to this embodiment is provided with a blade portion 7 that is pointed toward its tip, and the inner diameter dimension d1 of the blade portion 7 is shaped to expand from the base end to the tip (see Figure 1). By using this punch 1 to punch a hole (punch out) in a metal plate 2, when the blade portion 7 at the tip of the punch 1 bites into the metal plate 2, the force generated on the outer portion 2a of the blade portion 7 can be made smaller than the force generated on the inner portion 2b of the blade portion 7 in the metal plate 2. As a result, the deformation that occurs on the outer portion 2a of the metal plate 2 while the blade portion 7 is biting in is relatively reduced, making it possible to form the inner circumferential surface 3a of the hole 3 with high precision. Furthermore, in the punch 1 according to this embodiment, the blade portion 7 is formed in an annular shape. This allows the cutting edge 7 to bite into the material uniformly around its entire circumference, thus ensuring that the stress distribution generated on the outer portion 2a of the cutting edge 7 is uniform around its entire circumference, or minimizing any variation in the stress distribution. Therefore, this configuration makes it possible to accurately form the inner surface 3a of the hole 3 around its entire circumference.

[0025] Furthermore, in this embodiment, the outer diameter dimension d2 of the annular blade portion 7 is kept constant, that is, the outer peripheral surface 7b is shaped to extend in a direction parallel to the stroke direction of the punch 1. Therefore, deformation occurring in the outer portion 2a of the metal plate 2 where the blade portion 7 bites during punching, i.e., the outer portion 2a that constitutes the inner peripheral surface of the hole 3, can be suppressed as much as possible. Thus, the shape accuracy of the hole 3 can be further improved by making the inner peripheral surface of the hole 3 a shear surface as much as possible (in other words, by minimizing the generation of fracture surfaces). As an example, when the hole 3 is formed according to the embodiment, more than 90% of the area of ​​the inner peripheral surface 3a of the hole 3 in the direction of the axis X from the punching start side, more preferably more than 95%, can be a shear surface.

[0026] Although one embodiment of the present invention has been described above, the punch for a hole-punching apparatus according to the present invention may also have a configuration other than that described above, without departing from the spirit of the invention.

[0027] For example, in the above embodiment, the inner circumferential surface 7a of the blade portion 7 is given a shape that tapers in diameter from the base end to the tip end (see Figure 1), but of course, it is not limited to this. For example, although not shown in the figure, it is also possible to make the inner circumferential surface 7a, which widens in diameter from the base end to the tip end, a curved shape by cutting the tip surface of the punch 1 which becomes the blade portion 7 into a dome shape.

[0028] Furthermore, in the above embodiment, an example was given in which a through hole 8 is provided in the punch 1 including the blade portion 7, passing through the center of the punch 1, but of course, it is not limited to this. For example, although not shown in the illustration, the part of the punch 1 closer to the base end than the blade portion 7 may be solid without the through hole 8. [Explanation of Symbols]

[0029] 1. Punch for processing equipment 2 metal plate 2a outer part 2b Inner part 3 holes 3a Inner surface 4 Dies 5. Hole drilling machine 6 Through hole 7 Blade part 7a Inner surface 7b Outer surface 8 through holes X axis θ Taper angle d1 Inner diameter dimension d2 Outer diameter

Claims

1. A punch used in a hole-punching device for forming holes in a metal sheet by punching, The punch has an annular blade portion that is pointed towards the tip, A punch for a hole-punching device, characterized in that the inner diameter of the blade portion increases from the base end to the tip end of the blade portion.

2. The punch for a hole-punching apparatus according to claim 1, wherein the outer diameter of the blade portion is constant.

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