Study On Controlling Temperature And Optimizing Process Parameters Of Laser Assisted Milling In Superalloy

Nickel-based superalloy GH4698 has good comprehensive performance such as good oxidation resistance,resistance to corrosion,excellent high temperature strength and fracture toughness in the range of 500 to 800?.The superalloy is widely used in the manufacture of aircraft engine turbine disc,compressor plate,guide piece,and other important parts.However,nickel-based superalloy GH4698 is very difficult to manufacture with the small coefficient of thermal conductivity and large coefficient of friction,which leads to serious tool wear,big cutting force and low machining efficiency.Laser assisted machining(LAM)is an effective method machining difficult-to-machine materials,which uses a high power laser to focally heat a workpiece prior to removing material.At elevated temperatures,the machinability will change,resulting in reducing tool wear,improving surface finish and increasing material removal rates.This paper employs laser assisted milling technology to mill nickel-based superalloy GH4698,whose aim is to carry out simulation and experiment to research the process of milling superalloy.This paper mainly contains four aspects:According to the related theory of heat transfer,first this paper researchs the heat conduction and thermal radiation of workpiece,and then establishes the mathematical model of temperature field to accurately calculate and predict the temperature field distribution of workpiece.The finite element model about laser assisted milling GH4698 is established based on the mathematical model of temperature field,then temperature field simulation and experiment are carried out.The infrared thermometer is used to measure the temperature of the actual milling process of the workpiece,then analyse the test results and the simulation results to validate the correctness of the simulation model.The distribution of the temperature field of cutting area under different processing parameters is calculated by the difference in value between the monitoring point and cutting zone.The microstructure morphology,surface roughness,tool wear and the change rule of cutting force are researched by laser assisted milling experiment,so we can get the relationship among the process parameters,properties of materials processing and tool wear.A multi-objective optimization model is established to set milling parameters and laser parameters as optimization variables,minimum cost and maximum efficiency as the goal.We can employ genetic algorithm to optimize the model to get the best milling parameters and laser parameters.