The Turning Properties Study Of Laser Assisted Turning Of 45%SiCp/Al Composites

Particle reinforced metal matrix composites(PRMMCs)have been applied to the aerospace,automobile and other fields due to the high specific strength,low thermal expansion coefficient,and superior wear.However,it is very low efficiency and high cost for traditional machining PRMMCs due to the abrasive nature of the reinforcements causing rapid tool wear.Laser assisted machining(LAM)of PRMMCs is a promising technology,then some difficult problems in this process have to be solved urgently.Systematic theoretical and experimental investigations were conducted for solving these problems in LAM of PRMMCs in this paper,which is of great significance for high efficiency machining PRMMCs and the industrial application of LAM.Based on the Fourier heat transfer theory,a finite element model(FEM)for predicting the temperature field in LAM of PRMMCs has been developed.The model has been amended by the measuring temperature tests using infrared thermal imager.The influence law of laser parameters and cutting parameters on the temperature of cutting point has been studied by FEM simulation,and the empirical formulation of laser heating zone temperature is calculated by using multiple linear regression method.It provides the basis for the selection of laser parameters.Considering the material properties in high temperature,surface quality and the appropriate working temperature for cutting tools,the cutting layer temperature field in LAM was analyzed by using the numerical simulating method.And it provides the theoretical basis for carrying out relevant experimental research.A constitutive equation of developed Johnson-Cook plasticity model was proposed to describe the deformation behavior of the Al/Si Cp metal matrix composites over a range of LAM conditions.The relationship of stress depending on strain,strain rate,and temperature has been obtained by LAM tests,and a constitutive model was developed based on the experiment data.Macroscopical and micro FEM on LAM of PRMMCs has been developed using the finite element software.The macroscopical model was utilized to predict cutting forces precisely,which is convenient to select machining parameters of LAM.Micro model was applied to study the deformation and removal mechanism of matrix and particles.It laid the foundation for the selection of 45% Si Cp /Al composite laser assisted cutting parameters.A systematic laser assisted turning tests were conducted using the established integrated system.The effect of laser heating temperature on the chip morphology and surface formation was studied and it is noted that LAM provided a bigger shear angle,a lower specific cutting energy,a bigger on the saw tooth spacing,a more uneven height of saw tooth than in conventional machining.The ANOVA method was used to evaluate the effect of processing parameters on the surface roughness.Base on the smallest surface roughness and best signal-to-noise ratio the optimal machining parameters were selected.What's more,this paper also revealed that the effect of heating temperature on the surface quality,subsurface quality and mechanical properties.The effect of laser heating temperature on the cutting forces and specific cutting energy was studied and the results indicated LAM can reduce cutting forces and specific cutting energy obviously.The optimal laser heating temperature,tool material and machining parameters were determined by studying the effect of laser heating temperature,tool materials and cutting parameters on the cutting tool life.Through studying the tool wear mechanism in LAM of 45%Si Cp/Al composite,the physical model of the tool wear in LAM of PRMMCs has been proposed and the model reveals the mechanism of tool wear reduction with laser assistance.