Study On Laser Assisted Milling Of Nickel-base Superalloy K24Technology

K24is one kind of Cast superalloy which can work under very hightemperature. Its integral performance like high temperature strength, anti-oxidation,corrosion resistant, fatigue resistant and fracture toughness is better than the regularmaterials. Its working temperature can reach800°C or more, and it is the keymaterial used for the gas turbine engine parts working under high temperature.However, the machinability of K24is poor. When processing K24,the tool wearsseriously and its processing efficiency is low. One effective method to improve themachinability of difficult materials is laser assisted machining. Preheating thematerial locally can improve the material’s machinability so that can reduce toolwear and enhance processing efficiency. This paper present the simulation andexperimental study of laser assisted milling K24.The main parts of research work in this paper is state as follows:Firstly, this paper studies the mechanism of process of K24’s laser absorbingand heat arising, By comparing the simulation and experiment’s result of laserheating process, we obtain the YAG laser(wavelength1064nm) absorptivity of K24.By theoretically analyzing the physical character of K24, we figure out the mostsuitable temperature for this material to be milled using laser assisted millingmethod.Secondly, we establish the heat transferring model for finite element simulationof the process of laser assisted milling K24.Based on the model established above,we simulate the process of laser assisted milling and we obtain the temperaturedistribution of work piece. By comparing the simulation result and experimentalresult, we verified the accuracy of heat transferring model established above. Thenwe studies the law of the cutting zone’s temperature distribution affected by processparameters and supply the theoretical basis for successor experimental study. Basedon the analyzing results above, we obtain the selecting method of process parameterfor laser assisted milling.Thirdly,the experimental system used for laser assisted milling is built. Thissystem is composed of CNC milling tool, laser heating system and data collectingand analyzing system. The experimental study of laser assisted milling is executedunder this system. Consequently we verify the selection principle of the processparameters of laser assisted milling K24.We study the effect on the milling force byprocess parameters. The chip’s microstructure morphology, surface roughness,hardness and metamorphic layer reveal the machining mechanism of laser assistedmilling K24. Finally,this paper simulates and analyzes the deformation of thin-walledworkpiece machining by laser assisted milling. We establish the empirical formulaof the milling force and the preheating temperature. Then we study what is the effectof process parameter on thin-walled workpiece’s deformation. The simulation resultshows that the deformation of thin-walled workpiece is controlled within10μmwhen machined under suitable process parameter, therefore, the method of usinglaser assisted milling to machine K24thin-walled workpiece is feasible. At last westudy the effect of the way of putting the clamping device on thin-walledworkpiece’s deformation through the process of laser assisted milling, and then weverify the best way to put the clamping device to obtain the minimal workpiece’sdeformation.