1. The concept and cause of tearing

When the tensile stress of the cylinder wall exceeds the tensile strength of the material of the cylinder wall, the deep-drawn part will break at the "dangerous section" where the bottom fillet meets the cylinder wall malleable iron fittings.

mainly depends on

One aspect is the tensile stress in the force transmission zone of the cylinder wall. Another aspect is the tensile strength of the force transmission zone of the cylinder wall.

2. Factors affecting the tear

(1) The influence of sheet metal mechanical properties

(2) The influence of drawing coefficient m

(3) The influence of the corner radius of the die

(4) The influence of friction

(5) The influence of blank holder force

3. Measures to prevent cracking

Select materials with large hardening index and small yield ratio for deep drawing;

Properly increase the radius of the corners of the convex and concave dies in the drawing;

Increase the number of deep drawing;

Improve lubrication.

Practice has proved that the most prone moment of drawing cracks in the first drawing of a straight-walled cylindrical part is in the early stage of drawing.