Research On Laser-induced Oxidization Assisted Micro Milling Of Cemented Carbide

Cemented carbide is widely used in the cutting tools,geological mining tools,wear-resistant parts and mold industry due to its excellent properties such as high hardness,high strength and toughness.However,the machinability of the cemented carbide is poor.In order to improve tool life and surface quality,as well as to promote the application of cemented carbide,a hybrid processing technology named laser-induced oxidization assisted micro milling is proposed in this paper.Under the irradiation of pulse laser,the material ahead of the cutting region is oxidized,producing porous oxidation layer.Subsequently this layer is easily and rapidly removed by a micro cutting tool,thus the machining efficiency and tool life are improved significantly.This paper carries out the basic fundamental research on the laser-induced oxidization assisted micro milling,the main work and achievements are as follows:(1)Three-dimensional transient heat transfer model of cemented carbide under the irradiation of pulse laser is established.The temperature distribution on the YG20 cemented carbide radiated by pulse laser is analyzed.The effects of laser parameters such as power,frequency,scanning speed and spot diameter on the temperature distribution is investigated.(2)Oxidation experiments of YG20 cemented carbide material heated by an oven in the air atmosphere are carried out.The weight gain,phase identification and material microstructure under various conditions are analyzed.Based on the results of both the oxidation experiments and the temperature distribution modeling,oxidation experiments of YG20 cemented carbide material heated by pulse laser are carried out.The effects of laser parameters and atmosphere on the oxidation reaction are studied.The results show that the main oxide composition of the YG20 is CoWO4 and WO3.Porous oxide layer can be produced when laser average power is 5W or 6W and the frequency is less than 33 kHz with the fixed parameters of laser spot diameter of 0.5mm and scanning velocity of 0.5mm/s under atmospheric conditions.Material will be ablated when laser average power exceeds 6W under oxygen-enriched conditions.The auxiliary function of oxygen is not obvious.(3)A comparison of laser-induced oxidization assisted micro milling process with micro milling process in terms of cutting force,surface quality and tool life is carried out.The results show that the cutting force and the tool wear can be effectively reduced when using laser oxidization assisted micro milling.With the increase of milling length,laser-induced oxidation assisted micro milling can get better surface quality.