Experiment Research And Numerical Simulation On The Low Pressure Jet Assisted Laser Drilling

The recast layer, micro cracks and thermal deformation occur in the laser processing ofceramic materials, which seriously affect the surface quality. This paper introduces the low-pressure water jet assisted laser processing technology. This new type of composite processingtechnology can prevent the formation of the recast layer molten material, and reduce theresidual stress in the micro-cracks, by means of the kinetic energy of the water jet and strongcooling effect. The main contents of the paper on this new processing method are listed asfollowed:1) First, explore and study the low-pressure jet-assisted laser machining principle.According to the law of conservation of momentum, analyze the influence of the water jetvelocity on the molten material removal mechanism, and analyze the impact of compositedrilling factors on the surface quality.2) Comprehensive experiments are conducted to study the influence rules of processparameters such as the flow rate of the water jet, laser pulse energy, laser pulse width, laserrepetition frequency, and the secondary gas pressure on the surface quality, heat-affected zoneand processing efficiency of the high brittle difficult materials Al2O3ceramic. From the three-dimensional morphology of the angle of the punch, the difference is listed compared with aconventional laser drilling. The experiences verify the feasibility of low-pressure jet assistedlaser drilling laser processing on the improvement of surface defects, and this method isexpected to solve the recast layer after laser drilling processing. And, the washing and thecooling effect can reduce the slag accumulation and solve the heat affected zone problems.3) The process parameters of the composite perforated surface quality are studied. Basedon the research, the influences of process parameters on the hole shape are studied, through theobservation and analysis of small hole section morphology changes. At the same time, thereason why the holes change from the column to the cone after joining the water jet is conducted.4) On the basis of studying the mechanism of water jet laser processing, the form of theenergy conversion in the laser water jet perforation is studied. At the same time, the lowpressure jet assisted laser punching process are simulated with computer technology. Analyzethe pore evolution of materials in the process of temperature field, and calculate the changes ofpore shape on the basis of the change of the temperature field. The pore volume is calculatedwith pore sizes under different water jet velocity. The differences are contrasted between thenumerical simulation data and the experimental values measured under the same parameters,and this paper analyzes the reasons for the difference.