Numerical Calculation Of Temperature And Residual Stress Field About Laser Micro Processing

Laser Micro Processing is an important processing method for micro-sized components.At present,the research work focused on advanced ultra-fast pulse laser and high-end laser manufacturing equipment,but the research on surface quality of machining was less.Laser Micro Processing belongs to the field of thermal energy processing.It mainly relies on material melting and gasification to remove materials.However,the temperature field,residual stress distribution after processing,type of crack formation and measures to suppress crack are still being explored.In this paper,micro-hole machining test,surface micromachining tests and stress tests are carried out to study the temperature field and stress field distribution of micro processing and propose measures to reduce the crack.It is important to improve the surface quality of microminiature components and has important theoretical significance and application value.Based on the above-mentioned problems,a mathematical model of micro-hole laser machining was established,and the numerical simulation of the micro-hole temperature field was carried out.Based on the Fourier heat conduction equation,the Gauss heat source model and the temperature field finite element model were established by APDL.The temperature field distribution of SUS301 stainless steel,brass and ceramic materials with different laser parameters was studied.The finite element model of surface laser micro processing temperature field was established by reciprocating motion of Gauss heat source.By analyzing the changing trend of the temperature of the four positions on the SUS301 stainless steel path and the temperature trend of the workpiece temperature along the processing path at different time,the effects of laser parameters on the temperature field of workpiece and the temperature field distribution of different materials on surface micromachining were studied.The finite element model of micro-hole laser processing stress field was established.The stress distribution in the direction of thermal expansion of the micro-hole laser processing region is studied by unidirectional and multi-directional suppression.The finite element model of the stress field of the surface micromachining was established,by analyzing the changing trend of the equivalent stress of four positions on the SUS301 stainless steel path along the processing path and the changing trend of the equivalent stress of the workpiece at different time,the effects of laser parameters on the equivalent stress of the workpiece and the distribution of equivalent stress on the laser micro processing surfaces of different materials were studied.The effects of different laser parameters on crack formation and propagation were studied.The distribution of cracks in different materials with the same laser parameters was analyzed.The mechanism of different kinds of cracks was analyzed and the suggestion of reducing the crack was proposed.In order to prove the validity of the numerical calculation,the high speed camera was used to observe the process of micro-hole laser processing.The micro-hole morphology was observed by the ultra-depth microscope.The surface morphology and crack distribution were observed by scanning electron microscope(SEM).Residual stress distribution was measured by LXRD combined stress meter.By using the secondary development function of APDL,a numerical calculation system for laser micro processing is designed,which can quickly establish the finite element model and improve the numerical calculation speed.