激光辅助金刚石车削单晶硅的温度场建模及加工试验

Temperature Field Modeling and Machining Experiment of Laser-Assisted Diamond Turning Monocrystalline Silicon

以激光辅助条件下单晶硅的金刚石车削为对象,建立了激光辅助加热的温度场模型,利用COMSOL软件模拟得到单晶硅表面及亚表面的温度场分布;结合激光辅助加热的单晶硅表面测温试验,与温度场仿真结果进行了对比验证;最后开展了单晶硅激光辅助金刚石车削试验,研究进给量和背吃刀量一定的条件下,激光功率和主轴转速对切削力、表面粗糙度、切屑形态及刀具磨损的影响。结果表明,主轴转速为2000 r/min、激光功率32~40 W时,表面温度达到脆塑转变温度,500℃以上的亚表面传热深度超过6.8μm;激光软化材料效果受功率和主轴转速共同影响,随着激光功率增加和主轴转速降低,单晶硅加工性能和表面质量提升,刀具磨损降低,但激光功率达48 W时,加工热损伤导致单晶硅表面粗糙度大幅增加;激光功率40 W、主轴转速2000 r/min条件下,单晶硅表面粗糙度最低可达3 nm。

In this paper,diamond turning of monocrystalline silicon under laser-assisted conditions is taken as the object,the temperature field model of laser-assisted heating is established,and the temperature field distribution of monocrystalline silicon surface and sub-surface is simulated by COMSOL software.The experimental results of temperature measurement and temperature field simulation of monocrystalline silicon with laser assisted heating were compared and verified.Finally,the experiments of laser-assisted diamond turning with monocrystal silicon were carried out to study the effects of laser power and spindle speed on cutting force,surface roughness,chip morphology and tool wear under the conditions of constant feed and backdraft.The results show that the surface temperature reaches the brittle-plastic transition temperature when the spindle speed is 2000 r/min,the laser power is 32-40 W,and the sub-surface heat transfer depth exceeds 6.8μm above 500℃.The effect of laser softening materials is affected by both power and spindle speed.With the increase of laser power and the decrease of spindle speed,the machining performance and surface quality of monocrystalline silicon are improved and tool wear is reduced.However,the surface roughness of monocrystalline silicon increases greatly due to the thermal damage caused by laser power up to 48 W.The minimum surface roughness of monocrystal silicon can reach 3 nm under the conditions of 40 W laser power and 2000 r/min spindle speed.