Theoretical analysis of extrusion of rectangular, hexagonal and octagonal composite clad rods

Composite clad rods with non-axisymmetric cross-sectional areas are commerc ially important owing to their extensive industrial applications such as in electrodes, conductors and chemical devices. For instance, in the processi ng of superconductor wire, increasing the packing density involves closely packing superconductor rods which have a hexagonal cross-section next to ea ch other inside the high purity copper tube. During extrusion process, non- uniform deformation tends to occur because the core and sleeve of a composi te clad rod is usually composed of materials with different mechanical prop erties. The first recognized paper on round-to-square drawing/extrusion wit h variable corner radius was presented by Beer et al. in 1979. In this stud y, we present a model based on upper-bound theorem to analyze the extrusion of composite clad rods with non-axisymmetric cross-section. Velocity field s for both core and sleeve are generated with the assistance of a product's cross-sectional profile functions. Products with rectangular, hexagonal an d octagonal sections are chosen as the study objects. Also discussed herein are numerical results for various process variables such as semi-die angle , reduction of area, frictional condition of die, and product shape complex ity. According to these results, the extrusion pressure and product dimensi onal change are closely related to the process variables. (C) 1999 Elsevier Science Ltd. All rights reserved.