Effect of taper angle on processing load in forward extrusion

Abstract

There is actuality that forward extrusion processing is difficult when taper angle of die is less than 2°. Aim of this study is to reveal the reason why the forward extrusion processing is difficult in the case of 2°. To know the reason, we simulated forming processes with two-dimensional axisymmetric models under the same processing conditions. Each of two-dimensional axisymmetric model has different taper angles. Processing conditions are same reduction rate in area and taper angles from 25° to 2°. As a result, the smaller the taper angle, the bigger the processing load. To investigate the reason, we compared with contact pressure distributions in these angles. And then, it was revealed that the smaller the taper angle, the bigger the contact pressure distribution at the upper of taper section. When the contact pressure is large, it seems that friction force and the processing load become big. From the above, in the case of 2°, processing load is large. Therefore, depending on the machine, it is difficult to process the blank.