Gas hydrodynamics of metal cutting by cw laser radiation in a rare gas

Abstract

A quantitative physical model of metal cutting by cw laser radiation in the absence of chemical reactions was developed. An experimental study was made of the flow of the processing gas using a geometrically similar model. The distributions of the pressure and velocity of the gas were determined at the cutting front. Simplified mathematical algorithms for the thermal problem were constructed and calculations were made of the maximum depth of the cut (kerf) and cutting speed as functions of the laser beam parameters. Possible nonsteady-state characteristics of the motion of the melt and of the cutting front were considered. A thermal mechanism was proposed for the formation of the regular rippling of the kerf, based on a balance between capillary forces and forces exerted on the melt by the gas stream in the vicinity of the upper edge of the cutting front. Simple formulas were obtained for calculating the depth and period of the ripples.