Influence of Die Geometry on Drawing Force in Cold Drawing of Steel Tubes Using Numerical Simulation

In Železiarne Podbrezová, cold drawing process is the final process in production of precision seamless steel tubes. This particular technology utilizes multiple drawing sequences and intermediate annealing. From the physical point of view, it is nothing just the optimal use of plastic deformation during cold forming that grants the final tube dimensions. The drawing process itself is significantly affected by physical and metallurgical properties of the tube, the tool geometry, the lubrication, and the sequence of operations. This paper deals with the relationship between the tool geometry and the drawing force. The FEM-based numerical model of the process was prepared in DEFORM 3D in order to optimize the geometry of the die; eight die geometries were investigated in total. The numerical simulation itself considered a hot rolled hollow at Ø32 mm × 4 mm, cold drawn into Ø25 mm × 4 mm using die drawing (sinking) sequences only. Calculated drawing force showed that the change of the run-in angle of the die led to a decrease of the drawing force.