Photoplastic studies of three-dimensional strain field in the continuous cladding process

Abstract

A great development in CONFORM (Continuous Extrusion) technology is the application of the process for the cladding or sheathing of hard or soft cores to manufacture aluminium clad steel wires or fibre optic cables, in particular, OPGW and coaxial CATV cables. There is an alarming lack of understanding of the ways in which various forming parameters, such as strain, strain rate, friction, temperature and billet dimensions affect the flow pattern and quality of the final product. A key requirement for precise analysis of the forming process is an accurate description of the three-dimensional strain distributions within the body undergoing deformation. Because of the complexity of the die geometry in the continuous cladding process, plane-strain assumptions do not apply. An experimental technique with a capability for providing generalized three-dimensional strain information is sorely needed. It is toward this goal that the method of photoplasticity is used to obtain the strain distributions in the deforming body. This paper presents the procedures of the experiment and gives the three-dimensional strain distributions in the die chamber of the continuous cladding process.