Effect of die hole geometry on residual stress in cold drawn wires and bars

摘要

The influence of varying die semi-cone angles, parallel bearing lengths and transition radii on the material flow and residual stress in cold drawn wire and bars of C45 steel for a deformation of φ=0.255 was investigated with the aid of Finite Element Method (FEM). It was shown that material flow is influenced by both the semi-cone angle and the transition radius. The elastic energy, as a measure of the residual stress in the material after deformation, has a near linear relationship with the semi-cone angle. With a reduction of the semi-cone angle of 8° by 2°, elastic energy can be further reduced by approx. 8%. Independent of the semi-cone angle, residual stress is also reduced by appropriate selection of bearing length and transition radius. The influence of the parallel bearing on residual stress could be demonstrated and the underlying mechanism be explained.