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#140 Design of Blanking Dies (13) Blanking Dies with Different Constructions

Category : Shear Forming
January11, 2013
Regarding blanking dies, we have so far explained the fixed stripper construction taking the example of a very frequently used construction.
This is the construction in Fig. 1. This can be said to be the standard type of construction of a blanking die.
In this construction, the drawback can be said to be that the part being formed cannot be seen. There is also another point of concern. This is the change in the material while being processed.
The material on the die warps due to being hit by the punch. Although this does not matter much in the case of thin plates, this will become a problem in the case of thick plates.
Fig. 1

As a countermeasure for the part under formation not being visible and for the warping of the material, a blanking die with a movable stripper construction which makes it possible to use a material clamp as shown in Fig. 2 may also be used.
In this construction, the part being processed will be visible since the stripper is placed on the punch side.
Fig. 2

Since the number of components constituting the die becomes large, the cost of die preparation becomes proportionately higher. The construction as shown in Fig. 3 is also adopted for a blanking die. This type of construction is called the "inverted placement construction". The punch becomes the bottom die and the die becomes the top die. If blanking is done using this construction, since the product enters into the die, it will be necessary to discharge it. For that purpose, a component called a knock out is always necessary in the die.
The reasons for adopting this construction can be, wanting to minimize as far as possible the blanking warp, or when the push back method is used in which the material that has been processed once is pushed back. In the case of a push back, a spring is incorporated behind the knock out.
Fig. 3

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