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#023 Basics of Blanking Work (13) Shaping Work

Category : Shearing work
December18, 2009

In ordinary blanking work the cut end surface will be like that shown in Fig. 1(a). Some times it is required that this surface is a clean sheared surface (contour shape, or hole, or part of a shape). At such times, the cut end surface is cut slightly and finished in to a clean surface as shown in Fig. 1(b). This method of working is called "Shaping work.

Fig. 1

The important item in shaping work is the size of the depth of cut shown in Fig. 1 (b). The size of the depth of cut that can be removed by one operation is about 5% to 10% of the material plate thickness. For example, a rough guide to the value of this depth of cut is about 5% in the case of soft steel, 8% to 10% in the case of hard steel, and about 10% in the case of brass. When one shaping work is not sufficient, a second or a third shaping may be done.

The direction of shaping can be the upright placement method shown in Fig. 2(a) or the inclined placement method shown in Fig. 2(b).

Fig. 2 Direction of shaping

In the case of the upright placement method, the contact between the product and the die is uniform and the balance is good. In the inclined placement method, since the contact is made on the side of the fracture surface, the contact is unstable and there will be fluctuations in the way the grinding is done. Since shaping work is done in the next process step after the blanking operation is made, it basically increases the number of process steps. Further, even positioning is difficult. In addition, the problem in shaping is that the thinly ground scrap gets adhered to the die because of oil, etc., and is difficult to clean off, and hence it can cause scratches to be made on the product. In this manner, although this is a very well known process, it is used only rarely. Although this process step is included in progressive cutting works, if any mistake is made in the handling of the scrap, it can cause scratches on the products thereby causing the products to be discarded. When carrying out shaping operation in progressive blanking work, measures should be taken to make this scrap join with the scrap of ordinary blanking and remove them together.

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