Experimental And Numerical Simulation Investigation Of Micro Hole On The Stainless Steel Sheet By Fiber Laser Trepanning Method

Micro holes which its diameter is less than 0.5mm are processed on the Stainless steel sheet with thickness less than 0.2mm,whether using the traditional machining, or electroforming molding method are difficult to ensure processing quality and these methods are low processing efficiency and production cost is high; laser drilling with high efficiency, non-contact, high economic efficiency, versatility, easy to realize the advantages of automation, has been widely used in micro hole machining of SMT template. but, as the market for laser drilling quality requirements continue to improve, The common method of percussion drilling has not been able to meet the quality requirements of the hole.Because laser trepanning has the advantages of minimal heat affected area,hole style with high-precision, minimal taper and minimal recast layer, So it is being used in SMT template drilling area.This paper firstly explains the laser drilling and the interaction machanism of laser and material of laser trepanning process, the main technological parameters affecting the quality of laser trepanning arediscussed. Taking the SUS304 material as the research object, the temperature field numerical simulation of the laser trepanning process is carried out by using ANSYS APDL technology,which laid foundation for the selection of laser trepanning process parameters.The simulation and analysis indicates that with the increasing of Laser cutting speed, molten pool temperature,entrance hole diameter and exit hole diameter are all decreasing, and with the increasing of Laser power and duty cycle,molten pool temperature,entrance hole diameter and exit hole diameter are all increasing. Cutting speed plays a decisive role in reducing the heat accumulation in the process of laser trepanning.And it is found that the hole style of laser trepanning process has a certain taper.Secondly, based on the simulation analysis, selecting a specification for the 30mm×30mm×0.12 mm of SUS304 material, using of fiber laser for laser trepanning experiment research. The single factor control method is used to analyze the effect of laser power ratio, duty cycle,cutting speed, repetition frequency and auxiliary pressure on the quality of drilling.The experimental results show that with the increasing of the cutting speed, the repetition frequency and the auxiliary pressure, the entrance hole diameter will decrease; with the increasing of the duty cycle, the entrance hole diameter will increase; with the increasing of the laser powe ratio, the entrance hole diameter will increase first and then decreases; with the increasing of the cutting speed, the repetitionfrequency and the auxiliary pressure, the exit hole diameter will decrease;with the increasing of the duty cycle and the laser powe ratio, the exit hole diameter will increase. At the same time,it is found that with the increasing of the cutting speed, the edges of hole recast layer(heat affected zone) will decrease, but the edges of hole will appear wavy,become rough, hole smooth degree will become worse; With the increasing of repetition frequency, laser spot overlap rate will increase,the edge of the hole will become more and more smooth, hole smooth degree will be good.And the simulation results and the experimental results are compared and analyzed, which verifies the feasibility of the simulation analysis.Last, based on the experiment of single factor controlled variable method, the orthogonal experiment on the technological parameters of laser drilling is carried out.The experimental results show that the impact of factor significant order of drilling taper is that: cutting speed> duty cycle>laser power ratio> repetition frequency> auxiliary pressure, and the optimal combination of process parameters of laser trepanning is obtained:cutting speed is 12mm/s, duty cycle is 8%, repetition frequency is1.5KHz, power ratio is 85%, auxiliary pressure is 0.8MPa. The minimal drilling taper is obtained under the optimized parameters at 0.05°, And the micro hole edge heat affected is small, hole roundness is better, and higher drilling quality is kept up.