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#144 Design of Hole Punching Dies (4) Design of the Nest of Hole Blanking Dies

Category : Shear Forming
February 8, 2013

Normally, a blanking die carries out the blanking after positioning the blank and keeping it fixed.
This positioning part is called a nest. A nest is called by various names such as "positioning", "guide", etc.

Fig. 1 shows nests using plates. They are also called plate guides.


The nest in (a) is an integral type nest. This type is typically used. The nest in the figure (b) is a divided type nest. This type is used frequently in the case of large products.
A nest is fixed using four or more screws, and are positioned using two dowel pins (knock pins). The fixing method is the same as in the case of a divided nest, in that the relationship between the screw and the dowel pin becomes difficult when the nest becomes small.
In such situations, the minimum possible method of fixing is that of carrying out both fixing and positioning using two dowel pins for one screw.

Fig. 2 is a nest using pins. When a plate is used, there is the drawback that the escape of the stripper plate becomes large.
When a pin is used, not only the escape of the stripper becomes reduced but also it is possible to make the construction of the die simple.
Since positioning using pins becomes point contacts, the positioning accuracy becomes somewhat poor compared to plate guides.

Fig. 3 shows the thinking about designing the shape of a nest.


It is not good to prepare the nest faithfully according to the product shape. Even the positioning accuracy and ease of press operation are not good.
The key aspects of the product shape are taken, and a nest is prepared by escaping corners and finely detailed parts.
In addition, foolproofing is done so that it can be entered only from one side.
Further, do not forget to take measures to make it easy to insert the blank and to provide an escape that makes it easy to take out the product after pressing.

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