Design of mandrel in tube drawing process for automotive steering input shaft

Monobloc technology provides a homogeneous material along the complete tubular shaft without any discontinuity between the interconnecting tube and the stems as is found when the tubes and stems have been joined by welding. Cold tube drawing is a technique that can be applied for manufacturing of monobloc tubular shafts with several advantages such as high productivity and cost reduction. In drawing processes, the profile design of die and mandrel is the most important factor related to forming energy and deformation behavior of tubular material. The present study is concerned with the investigation about the process parameters related with tool configuration. In order to obtain successfully formed shaft without any defects, conventional straight type and terraced type of mandrels have been proposed. For both types of mandrel, FE analyses of drawing processes were carried out and a ductile fracture criterion was utilized to predict forming failure. As the results, the advanced mandrel shape, which effectively can transmit drawing force to deforming tube, was designed.