JPH0244902Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a stripper device for a hole punch.

(Prior Art) Conventionally, as shown in Fig. 1, this type of device is
A urethane stripper c is fitted onto a hole punch b attached to a punch holder a, and when punch holder a is moved downward to drill a hole in a blank w on a die d, the stripper c is connected to the punch holder a and the blank. It is known that the stripper c is compressed and deformed between the stripper c and the blank w when the punch b is pulled out from the blank w by upward movement of the punch holder a, and the blank w is held down by the elastic restoring force of the stripper c. In this case, the inner diameter of stripper c is made slightly smaller than the outer diameter of punch b to provide a tightness margin for stripper c against punch b, but due to manufacturing tolerances and wear due to repeated use, the tightness is lost and stripper c falls off. Therefore, the upper end of the stripper c is generally bonded to the punch holder a with an adhesive e.

(Problem to be solved by the invention) When the stripper C is compressed, the middle part deforms so as to bulge outward, so a bending moment acts on the upper end part. If the stripper c is used, the adhesive part at the upper end may peel off, causing the stripper c to fall off.

An object of the present invention is to provide a device that solves these problems.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a device in which a stripper made of urethane or other elastic material is fitted onto a punch for making a hole attached to a punch holder. It is characterized in that an annular groove is formed on the outer periphery of the end on the punch holder side, and a substantially U-shaped clip for pinching the stripper is fitted into the annular groove.

(Function) The stripper is compressed and deformed into an oval shape by the clamping force of the clip at the tip end on the punch holder side.
It is crimped onto the punch with an interference amount corresponding to the diameter reduction in the short axis direction. Since this tightening margin is not obtained by the stripper itself, it does not change much even with repeated use, and no external force is applied to the stripper in the direction of pulling it out from the punch, so the stripper is securely attached to the punch. It is held in place and does not fall off.

In addition, the stripper is only restrained by the clip at the end on the punch holder side, and the stripper can be expanded and contracted smoothly, and the clip is approximately U.
Because of the shape of the stripper, the outer periphery of the stripper is not completely constrained, and the stripper is allowed to bulge in the radial direction due to deflection in the opening direction of the clip, causing large stress to be applied locally to the stripper. is prevented and the durability of the stripper is improved.

(Example) Referring to FIG. 2, 1 indicates an upper die, and 2 indicates a lower die.A punch holder 4 in which a punch 3 for making holes is implanted is attached to the upper die 1, and the upper end is attached to the punch 3. A stripper 5 made of an elastic material such as urethane is fitted onto the holder 4 while the die 6 is embedded in the lower die 2 and faces the punch 3. The punch 3 has a free length longer than the protruding length of the punch 3 from the holder 4, so that when the upper mold 1 moves downward, the lower end of the stripper 5 first contacts the blank w, and as a result of the subsequent downward movement, the stripper 5 contacts the blank w. The stripper 5 is compressed, and then the lower end of the punch 3 protrudes below the stripper 5 to punch a hole in the blank w as shown in the third figure. When the punch 3 is pulled out from the blank w, the blank w is pressed down from above by the elastic restoring force of the stripper 5.

The stripper 5 has an annular groove 5a on the outer periphery of the end on the holder 4 side, that is, the upper end, and a U-shaped clip 7 as shown in the fourth figure is fitted into the annular groove 5a to pinch the stripper 5. At this point, the clip 7 has an inner diameter that is 1 to 1 mm larger than the bottom diameter of the annular groove 5a.
The stripper 5 has a small diameter of 2 mm, and when it is fitted into the annular groove 5a, the upper end of the stripper 5 is in the direction in which the clamping force is applied when the stripper 5 is not fitted onto the punch 3.
The diameter was reduced by about 0.5 to 1 mm and compressed into an oval shape.

However, according to this, the stripper 5 is crimped onto the punch 3 with a tightening margin corresponding to the diameter reduction, as explained in the section of the above-mentioned operation, and is securely fitted and held thereon.
The stripper 5 does not fall off even after repeated use.

In the illustrated example, the annular groove 5a is formed in two stages, upper and lower, and when the upper annular groove 5a is cut by adjusting the length of the stripper 5, or when the tightening becomes weak, etc., the annular groove 5a in the lower stage is formed. The clip 7 can also be attached to the clip 7.

(Effects of the invention) As described above, according to the invention, the stripper can be reliably retained in the punch even after repeated use, and the radial bulge deformation caused by compression of the stripper can be reduced to a substantially U-shape. This can be absorbed by the deflection in the opening direction of the formed clip, preventing large stress from acting locally on the stripper and improving durability.Moreover, the structure is such that an annular groove is formed in the stripper and the clip is inserted into this. It only needs to be fitted, and the structure is simple and can be obtained at low cost.

[Brief explanation of the drawing]

Fig. 1 is a cut-away side view of a conventional device, Fig. 2 is a cut-away side view of an example of the device of the present invention, Fig. 3 is a cut-away side view of the device during drilling, and Fig. 4 is a cut-away side view of the clip-fitting portion of the stripper. FIG. 3... Punch, 4... Punch holder, 5... Stripper, 5a... Annular groove, 7... Clip.

Claims (1)

[Scope of utility model registration request] In a device in which a stripper made of urethane or other elastic material is fitted onto a hole punch attached to a punch holder, an annular groove is formed on the outer periphery of the end of the stripper on the punch holder side, and the stripper is inserted into the annular groove. A stripper device for a hole punch, characterized in that a substantially U-shaped clip for pressing is fitted.