Experimental Study On Laser Induced Cavitation Micro Blanking

For the processing of metal foil blanks at micro-scale,the use of precision die blanking methods has the problems of limited punch life,die squeeze wear,and difficulty in die centering.Laser drilling technology has problems such as ablation and absorbing layer cannot be compensated,It is proposed to use the plasma shock wave,collapse shock wave and micro-jet generated by laser-induced cavitation to replace the rigid punch to load the workpiece to achieve the blanking process;And the laser-induced cavitation has the advantages of strong controllability,high repeatability and accurate positioning,which can achieve precise alignment of the pressure action position and the die hole;at the same time,the liquid can be automatically replenished after each blanking,which can achieve continuous punching,The main work of the paper is as follows:Firstly,a high-speed camera was used to study the laser-induced cavitation micro-blanking process.The blanking process under different laser focus positions and different laser energy conditions were analyzed,Studies have shown that the laser-induced cavitation micro-blanking process is a process in which laser plasma shock wave,cavitation collapse shock wave and micro-jet are loaded together.The first blanking force of the copper foil comes from the plasma shock wave,and the second blanking force comes from the blast shock wave and micro-jet.Secondly,the ANSYS finite element analysis software was used to conduct two main mechanisms.The pulsation characteristics of laser-induced cavitation at different stages of expansion,rupture and collapse are analyzed,and compared with the results of high-speed photography,the propagation characteristics of shock waves generated by laser breakdown liquid are further studied.By establishing a simulation model of laser parameters and copper foil stress and strain distribution,the stress distribution and strain distribution of copper foil under cavitation pressure loading is explored,and the simulation results are compared with the experimental results to verify the correctness of the built simulation model.Thirdly,The influence of laser focus position(H=0?4mm),laser energy(E=10.3?50.8m J),laser action times(N =1?6times)and copper foil thickness(T=20?70?m)on the copper foil blanking were experimentally studied.It was found that with the change of laser focus position and laser energy,copper foil will undergo laser ablation,plasma ablation,plasma shock wave,collapse shock wave and micro-jet.The laser plasma shock wave will rapidly decay when propagating in water,but within a certain distance range,when the intensity of the shock wave attenuation is greater than the breaking strength of the material,the copper foil can be blanked.Subsequently,the orthogonal test was completed,and the experiment obtained the influence order of various factors on the average deformation depth of the copper foil,and obtained the optimized parameters.After observing the workpiece,the laser-induced cavitation loading and blanking of the small hole edge surface can effectively avoid ablation,and there are no obvious defects such as burrs,cracks and curling.After the observation of the blanking section,the ratio of the bright band is high,reaching 60%,and the quality of the blanking section is good.Finally,using laser-induced cavitation micro-blanking technology to punch holes with various shapes in other metal materials,the practical application prospect of laser-induced cavitation micro-blanking technology was explored.