Local energy adjustment mechanism in a novel laser-enhanced plasma arc heat source

Abstract

This study aims to enhance the localized energy of the plasma arc to meet the requirement of thick metal plate welding. To achieve this, a novel hybrid heat source by coaxial arranging the laser and plasma arc was proposed, named laser-enhanced plasma arc (LPA). This special torch combines the two kind sources by a tubular tungsten electrode which the laser passes through, use laser to heat localized plasma arc to modify the energy distribution. The three-dimensional temperature field was measured to clarify the effect of laser on plasma arc energy distribution and the absorption characteristics of laser by plasma arc. The numerical simulation model was established to reveal the influence mechanism. Results show that there is a high laser absorption region in the plasma arc, and it exists obvious effects of plasma arc pressure and temperature on laser absorption rate. The location and size of the high laser absorption region change as the welding parameters because the temperature and pressure of plasma arc change. The results also substantiate that the hybrid source energy can be adjusted locally to increase the effective flame length of the plasma arc by changing the laser energy and plasma arc parameters, which is beneficial for thick metal plate welding.