Research on the influence of the jet flow regime in the kerf on the cutting surface accuracy in WJGL

Water jet-guide laser processing technology (WJGL) has a good application prospect in the field of non-metallic materials with high brittleness and hardness for its high machining precision. However, the premise of smooth and efficient machining is to ensure that the jet can transmit light energy stably into the material. Especially in complex trajectory cutting, the jet in the channel is prone to instability, which affects the processing results. Therefore, the purpose of this paper is to construct a complex environment with sufficient turbulence of the jet in the cutting channel, and carries out a research plan with sharp corners. The forming mechanism of the machined surface was deduced by visual observation. Combined with the simulation results, the key factors of the disturbance of the jet flow pattern are obtained. It is considered that vertical angular vortices are formed at the corners due to the high-pressure gradient induced by the jet, which causes the laser energy to diverge from the water-fiber prematurely, and the processing accuracy declines. Finally, an optimization scheme is proposed to replace the straight corner with a low-curvature cross arc, which can avoid the problem of accuracy and efficiency decline caused by jet instability. After optimization, the surface quality of cutting surface is improved by 6 times.