A numerical simulation of temperature field in plasma-arc forming of sheet metal

摘要

Flexible forming using plasma arc (FFUPA) is a newly developed method of sheet metal forming. It makes the forming by means of thermal stress and thermal strain without mould and die, and is recognized as a promising forming method in developing new products. In this paper, the mechanism and features of FFUPA have been studied. Two basic forms of flexible forming, bending towards and away from plasma arc, have been analyzed and discussed. In order to provide the basis of simulation analysis of thermal stress and thermal strain during FFUPA, a mathematical model for heat transfer of FFUPA has been developed. Computational analysis has been performed for thermo-physical parameters of the sheet metal, scanning speeds, arc powers and cooling conditions. The influence of these factors on temperature field distribution was calculated and analyzed. The results indicate that thermo-physical parameters influence the distribution of temperature field primarily and the sheet metal with small heat transfer coefficient is easy to be formed. Within the given surface temperature of sheet metal, the higher scanning speed can perform the better forming effect. Under specified arc power, material and scanning speed, the shapeable sheet metal has a thickness limit. With the cooling system, distribution of temperature field can be adjusted and hence final shape can be controlled.