Comparison of die geometry for cold drawing of multi-rifled steel tubes

Multi-rifled tubes, i.e. tubes with multiple inner grooving are used in heat exchangers and boilers, providing favourable heat transfer conditions due to turbulent flow of cooling medium. Therefore, strict requirements are placed on the geometry of inner rifling. In production of such tubes, cold drawing with free-to-rotate rifled plug is the final drawing operation to achieve required dimensions. A Finite Element Method (FEM) based numerical model of the process was prepared in order to optimize the geometry of the die. The results of numerical simulations for two different die geometries show the difference in material flow and corresponding drawing force. The final dimensions of the tubes after drawing were compared with the customer`s requirements and a good agreement was found