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#150 Design of Hole Punching Dies (10) Design of a Die Set for Hole Punching

Category : Shear Forming
March22, 2013

The die sets used for hole punching (perforating or piercing) are explained below.

The parts that need to be taken care in die sets are shown in Fig. 1.

Fig. 1

Regarding the size (area), it is common to select a standard die set matching with the size, etc. of the die plate.
When fabricating an original die set, the size will be equal to the plate size plus the area required for mounting the guide post. In order to reduce the weight of the die, some unnecessary parts are scraped off. If there is no particular problem with the outer periphery, it can be left as it is when cut.
The thickness (T) of the punch holder and the thickness (T1) of the die holder are determined considering the size of the plate. The lower limit can be about 30 mm.
Care should be taken about the punch holder since there is also the relationship with the spring.
Care should be taken about the relationship between the length of the guide post and the die height (shown by X in Fig. 1), particularly in the case of a structure in which the die height becomes lower after regrinding.

Fig. 2 shows the scrap dropping hole of a die holder. Several holes are punched simultaneously.
The machining of the die holder is made easy. The aim is to prevent clogging of the scrap. When there are several scrap dropping holes, as far as possible the design is made so that they can be machined using the same tool (end mill, etc.).
Considering the strength of the die plate, care should be taken so that a too large scrap dropping hole is not made.

Fig. 2

In the case of hole having a projecting part as shown in Fig. 3, the projecting part can easily get damaged if designed as in Fig. 3(a). Even if it is cumbersome, design the scrap removing hole so that the part below the projection is supported. It does not matter even if the receiving part becomes thin.

Fig. 3

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