Design and development of a novel load-control dieless rod drawing system

Abstract

This paper describes the design and development of an experimental machine capable of drawing metallic rod or wire without the use of metal forming dies as used in conventional wire/rod drawing process. Conventional wire and rod forming processes have a number of drawbacks which include die wear, lubrication requirements, pre-cleaning of precursor stock and a requirement for multiple passes through dies to achieve significant reductions in diameter. Consequently, a dieless drawing system has been developed to address the aforementioned drawbacks. This novel system can effect a reduction in diameter of a metallic rod without the use of drawing dies by heating a localised area of the rod while a tensile load is applied along its longitudinal axis. The dieless drawing process was feasible through precise control of process parameters such as drawing velocity, temperature and rates of both heating and cooling. The machine operated in a closed-loop system where identification of the onset of yield in the workpiece material was used to control the process, and consequently, allow steady state dieless drawing. The machine was designed to draw both mild steel and high carbon steel rods at elevated temperatures. The results of an experimental programme carried out with the machine indicate that the dieless forming method is feasible for the production of metallic materials in wire or bar form.