The Use of Rational Design in the Development of an Improved Plug Tool for the Rotary Tube Widening Process

To improve the performance of any metal forming process, a minimization in the process load parameters is needed. The used die geometry significantly affects the process performance. Several die designs were developed to increase efficiency and reduce defects. This paper investigates the effect of the widened plug profile on the tube widening process, and considers the use of the Constancy of the Ratios of successive generalized Homogeneous Strain (CRHS) increments concept for different die profiles. Five widening process parameters are considered: the axial plug load, the widening torque, the variation in temperature, the widened tube thickness, and the widened tube quality. The investigation shows that an improvement in the widening process parameters was achieved using (CRHS) plug design leading to a 25% increase in the maximum widening ratio compared to other plug designs. This was achieved at relatively low tube ends temperature and an improved quality of widened tube ends.