Thermal-mechanical model of the tube elongation process in Diescher's mill

The steady-state finite element approach is used to model the tube elongation process in Diescher's mill. The material is deformed between two rotating cone shaped rolls and a plug. The material is dragged by the rolls, moves forward and rotates. The analysis of the process is performed in the cylindrical coordinates. Tube ovalness is neglected. The material flowing in the circumferential direction is accounted for. The velocity field components in r,θ,z directions are discretized using parabolic shape functions. An iterative algorithm is employed for correction of the outer and inner free surfaces that determine the control volume. The material flow and torsion, distribution of the effective strain and temperature are computed and analysed for the tube elongation process in Diescher's mill using a parabolic plug.