Study On Temperature Field Simulation In Laser Assisted Micro Milling

Micro-milling technology has played an important role in manufacturing micro-parts,especially complex structural parts,owing to its high flexibility,workpiece materials diversification,high efficiency and high machining accuracy.However,problems such as heavy tool wear,poor surface quality,low efficiency and high cost exists in the micro-milling processing of hard-to-machine materials such as superalloys,structural ceramics and composites.Laser assisted machining can improve machinability of material by locally heating the material before the cutting tool to reduce the hardness and shear strength of the workpiece material.Laser assisted micro milling technology which combines the advantages of micro milling and laser assisted machining can achieve a good machining effect with appropriate laser parameters and cutting parameters.In this paper,the thermal model and cutting model of pulsed laser assisted micro milling are built and the influence of laser parameters on the temperature distribution and the machining process are studied.The main work and achievements are as follows:(1)Based on the analysis of the heat transfer between laser and workpiece during the laser heating process,the heat transfer model is built and solved with the finite element software.The characteristics of pulsed fiber laser source are analyzed,and a pulsed laser heat source model is built(2)The influence of laser parameters such as laser spot diameter,laser scanning speed and single pulse energy on the temperature field distribution is analyzed based on the thermal model.The model have been validated using surface temperature measurements by an infrared thermography.(3)Simplify the micro-milling process and a 2-D cutting model,including the constitutive model of material,the friction model between chip and rake face,the chip forming principle and the generation of cutting heat,is built.The simulation results of laser assisted micro milling and conventional micro milling are compared with proper simulation parameters for Ti6Al4 V titanium alloy.The results show that the maximum stress decreases about 30%,the radial thrust force decreases about 57%,and the main cutting force decreases about 20%,which indicates that the laser preheating material can improve the cutting performance of the difficult-to-machine materials.