Reserch On Drilling With Mql Of CFRP-Ti-CFRP Stacks

Carbon fiber reinforced polymer(CFRP)/ titanium alloy(TI)laminated materials are widely used in modern aerospace industry due to their excellent mechanical / physical properties.As the main load-bearing component of aircraft structure,CFRP / Ti laminated structure often bears extreme force and thermal load in the process of aircraft flight,so the quality,efficiency and reliability of assembly and hole making are very high in the process of machining.However,due to the poor machinability,it is difficult to control the machining damage in the drilling process,especially in the three-layer CFRP-Ti-CFRP laminated structure.Therefore,how to ensure the high efficiency,high quality and high reliability of hole making is the key problem to be solved in CFRP-Ti-CFRP laminated structure.In view of the above problems,this paper uses the micro lubrication cutting method to replace the traditional dry cutting,and makes in-depth research and Discussion on the damage generation,process method and the correlation analysis between micro lubrication parameters and processing damage.(1)In order to get the rule of the influence of micro lubrication on the temperature of the laminated structure,a micro lubrication cutting finite element model of CFRP-Ti-CFRP laminated structure is established.The drilling temperature of the given position of the laminated structure is simulated and calculated.The cutting temperature of the cutting test is measured by using the infrared thermal imager.The accuracy of the simulation is verified by comparing with the simulation.The results show that the drilling temperature of traditional dry drilling at the junction of two-phase heterogeneous materials exceeds the glass transition temperature of resin,resulting in the modification and softening of resin and the decline of mechanical properties.After micro lubrication drilling,the cutting heat accumulation of laminated components is reduced,the temperature at the interface of two-phase heterogeneity is effectively controlled,and the problems of CFRP resin peeling and burn are restrained.(2)A test platform for the validation of micro lubrication drilling process of CFRP-Ti-CFRP laminate was built,and a large number of experiments were carried out.Combined with the analysis of the drilling force behavior in the experiment,the law of drilling force variation in different stages of micro lubrication drilling and traditional drilling is found.Compared with the traditional drilling,the drilling force in each stage of micro lubrication drilling is more stable and less volatile,and the peak value of drilling force is obviously lower than the traditional drilling.Excessive drilling force is one of the important factors leading to the delamination at the exit of CFRP,so the maximum drilling force is reduced,the delamination at the exit is reduced,and the quality of drilling is improved.(3)The influence of micro lubrication cutting parameters on the experimental drilling force is studied.The results show that with the increase of cutting speed and the decrease of feed rate,the drilling force decreases gradually.Therefore,the reasonable use of high speed and low feed process parameters is conducive to suppress the defects of laminated structure and improve the quality of laminated structure.(4)The difference of hole surface roughness of CFRP laminates under two kinds of drilling conditions was compared,and the relationship between the surface roughness and the process parameters such as speed and feed rate was analyzed.The results show that compared with the traditional dry drilling technology,the micro lubrication drilling technology can greatly reduce the chip erosion on the hole wall of CFRP layer,which is conducive to the chip removal and breaking of the laminated structure,so as to effectively reduce the hole wall roughness.(5)Based on the coupla function,the correlation between the micro lubrication drilling cutting force and the surface roughness and the workpiece surface hardness is quantitatively analyzed.The edge distribution function and copula function of the best variable are fitted by AIC criterion and maximum likelihood method.The correlation between cutting force and surface roughness and surface hardness is quantitatively evaluated and discussed by Kendall rank correlation coefficient.