Stretch piece

There are many kinds of stretch piece. Due to its different shape, the position of deformation zone, the nature of deformation, the stress-strain state and distribution law of each part of the blank are quite different, some even in essence.

 

1. In the process of drawing, the flange part of the blank is the main deformation area, and the rest part has only a small amount of deformation, but it has to bear and transfer the tensile force, so it is the force transfer area;

 

2. The deformation zone is subjected to tangential compressive stress and radial tensile stress, resulting in tangential compression and radial elongation. When the deformation degree is large, the main deformation area is buckling and wrinkling.

 

3. The wall thickness of stretch piece is not uniform, the wall thickness at the mouth is slightly thickened, the wall thickness at the bottom is slightly thinner, and the thinning near the bottom fillet is the most serious;

 

4. The hardness of each part of stretch piece is also different. The deformation degree of the mouth is large and the cold work hardening is serious, so the hardness is high; while the deformation degree of the bottom is small, the cold work hardening is small, so the hardness is low.