Design method of anti-cracking self-piercing riveting die

The invention discloses a design method of an anti-cracking self-piercing riveting die, which comprises the following steps: (1) listing all curved surfaces capable of providing material flow in the riveting process of a riveting die part, as the self-piercing riveting die has the characteristic of complete central symmetry, as shown in Figure 1, L1 is the length of a curve 1, and R2 is the lengthof a curve 2; l2 is the length of a straight line; l3 is the length of the curve; l4 is the length of a straight line; the L5-L8 and the L1-L4 are the same and symmetrical; l9 is a virtual straight line and is the total straight line length of L1-L8 in the horizontal direction; (2) assuming that the ductility of the material is I%, and assuming that the compatible ductility of the riveting die isI '%, the following calculation formula is provided: and (3) if I' is greater than I, the riveting die cannot prevent the material from cracking, and if I 'is less than I, the riveting die can prevent the material from cracki