In the production process of metal stamping parts, the punching size is too large or too small and there is a big difference with the punch size. In order to solve this problem, we should not only consider the planning size of forming punch and die, processing accuracy and blanking clearance, but also consider from the following aspects.
1. Due to the burr of metal stamping parts produced during blanking, it is necessary to study the cutting edge and check whether the blanking clearance is reasonable. It is mainly caused by the instability of stamping parts during bending. The key to solve the problem is to hold down the material before bending and prevent the stamping parts from sliding during bending, aiming at U-shaped and V-shaped bending.
2. With the increase of tensile stress, the stamping parts tend to turn over and twist. When turning over, the punching size will be smaller. The strong pressure on the material will deform the material, which will lead to the larger punching size. When the pressure is reduced, the punching size will be smaller.
3. If the end is trimmed with inclined plane or arc, the punching part is easy to overturn and smear due to the relief of blanking force, so the punching size will be larger. When the punch end is flat (no inclined plane or arc), the punching size will be smaller.