Optimum Die Design in Drawing of Square Section Rod from Round Bar

Drawing of square section rod from round bar can be done with two die shapes. In the first die shape, deformation starts from corners of the square and in second die shape, deformation starts from sides of square. This article has compared the drawing force for both die shapes and as a result optimum die shape was determined. Due to complexity of metal flow inside the die, analyzing of actual process was difficult and upper bound approach has applied based on equivalent axisymmetric curved die. In equivalent process, in each position on the die axis, perpendicular cross sections on both actual and the equivalent die have the same area. By determining the profile of the equivalent curved die, a velocity field inside the die was presented. Then, internal, shearing and frictional powers were calculated and relative mean draw stress was estimated by equating the summation of these powers with required external power. As a final result, the die shape which required less force was introduced as optimum one