Numerical Simulation And Experimental Study Of Picosecond Laser Drilling On Brass H59

Brass is a common metal in the field of electronics production,hence there is a significant engineering application value to research technologies of microhole machining.Compared with the traditional machine drilling,laser drilling has many advantages,such as bigger depth-diameter ratio,less recast layers,smoother wall of hole,cleaner surface,higher efficiency,etc.Therefore it is very important to analyze the effect of laser parameters on the quality of microhole and optimize experimental parameters.This thesis carried out an investigation for laser drilling of brass H59,including theoretical analysis,experimental study and numerical simulation.Control variable method was used to analyze the effect of laser parameters on the quality of micro-hole,and based on control variable methods,orthogonal experiment was used to obtain the optimal parameters for picosecond laser drilling of brass H59 with thickness of1 mm.The main research contents are as follows:(1)In the aspect of theoretical analysis,the law of laser machining of metallic materials was introduced;its influence of laser wavelength,material temperature,surface condition and material properties on laser energy absorption was analyzed;the difference in mechanism of interaction between long pulse laser and short pulse laser and machining of metallic materials was also elucidated;the influence of laser and metal on the laser energy absorption was discussed.Based on these theories,the coupling of electron and lattice of double-temperature model was used to research the mechanism of ablation on metal material by picosecond laser.The theory of galvanometer scanning machining was analyzed for picosecond laser drilling on brass H59.(2)In the aspect of experimental research,the influence of the parameters such as laser power,repetition frequency,element count and scanning speed on the micropore quality of H59 brass was studied based on the control variable method.Based on control variable method,considering the mutual effects of laser parameters,orthogonal experiment was used to optimize experimental parameters and parametersfrom great to small influence were recurrence frequency,laser power,scanning speed,times on the quality of microhole.Finally,the optimal parameter(laser power 49W(70%),recurrence frequency 2 MHz,times 300,scanning speed 500 mm/s)was obtained.Smoother wall of hole,cleaner surface,entry hole with 243.572 ?m,exit hole with 218.572 ?m and taper angle with 1.437°were gained with the optimized parameters.(3)In the aspect of numerical simulation,based on the theory of laser drilling and experimental research,APDL language in ANSYS and the optimal parameters were used to simulate the temperature field of laser drilling and the change of micro-hole diameter.The reason for errors was analyzed from the results of the numerical simulation and experimental research.