An investigation into the effect of redundant shear deformation in bar drawing

Redundant shear deformation in bar drawing results in the increase of the energy required for deformation of the material. The development of this deformation depends mainly on die angle, friction coefficient between the die and the bar, reduction percentage in cross-sectional area of the bar, mechanical properties of the material and the drawing velocity or strain rate. The main objective of this investigation is to obtain the optimum conditions for the minimum energy and consequently reducing the cost of the process. In order to achieve the objective, both experimental and numerical approaches are employed for the investigation. Two materials, copper and steel, are tested under different friction conditions, die angles and drawing velocities. The optimum die angle for bar drawing is assumed to obtain when the strain and stress distribution across the diameter of the bar becomes uniform and that the load reaches its minimum in the load-die angle curve. The numerical results verified by experimental achievements indicate that friction has significant effects on the optimum die angles. The results confirm the optimum die angles predicted by the relation available in the literature . The results also reveal that the optimum die angle slightly decreases with the increase of drawing velocity.