Study of cold tube drawing by finite-element modelling

The potential for optimising commercial cold drawing of steel tubes by reducing the number of drawing passes whilst minimising the induced tensile residual stresses has been investigated. Modelling techniques have been used based on a commercial implicit finite-element (FE) code. The FE model takes into account the elastic-plastic response of the tube, the elastic response of the tools and the adiabatic and frictional heating effects during drawing. The model has been validated against the measured surface temperature, drawing load and mandrel reaction force. Key model outputs such as residual stresses, drawing force and temperature distribution have been predicted. In addition, an optimisation procedure has been developed based on the Cockcroft-Latham workability failure criterion to determine whether it is possible to reduce the number of drawing passes for a given size reduction. The optimisation procedure can be used to design optimum dies and mandrels for tube drawing and minimise the time and cost associated with lengthy works trials in bulk metal-forming processes. (C) 1998 Elsevier Science S.A. All rights reserved.