Issue 30

C.J.Su et alii, Frattura ed Integrità Strutturale, 30 (2014) 502-514; DOI: 10.3221/IGF-ESIS.30.61 510 Figure 11 : The hydrostatic pressure with different pitch. a) 2.6 mm b) 3.5 mm c) 4.6 mm d) 5.7 mm Figure 12 : Stress distribution of fine blanking 1/6 in deformation zone. Fig. 13 shows the relationship between the maximum compressive stress and the convex molding quantity. It is obvious that the stress of the compressive deformation zone significantly increases along with the increasing pitch. Because under the same press, pitch that is too big will produces less hydrostatic pressure. Thus the quality of the obtained blanking off surface is relatively poor. If the BHF is increased to obtain a good cutting surface, there will be a corresponding increase in punching die load. Through many times of finite element simulations, it can be obtained that smooth surface can reach about 80% when the pitch is equal to 3.5mm, which is considered as the ideal pitch. Figure 13 : The relationship of maximum equivalent stress and convex of pouch in plate.