The Research On Helical Milling Experiments Of C/E Composites

Carbon fiber/epoxy resin composites(C/E composites)have excellent properties such as high ratio of strength/density and stiffness/density,good fatigue resistance and corrosion resistance,etc.They are wildly used in manufacture of aircraft fuselages,wings and vertical fin in aerospace industry.A large number of holes are required for the assembly of aircraft fuselages and wings.However,in traditional drilling process of C/E composites,obvious material defects are often observed,such as burrs,delaminating,tearing and so on.These defects have seriously effect on material performance and fatigue life.At the same time,the tools wear seriously and the processing efficiency is low.Helical milling processing is a kind of new hole-making technique in aerospace industry,which can reduce the cutting force and cutting temperature to improve machining quality and extend tool life.This paper aims at the research of cutting force and machining damage in helical milling of C/E composites.The main research contents are as follow:The shape of un-deformed chip is analyzed according to helical milling kinematics.The milling force model of helical milling is established from the perspective of micro cutting.The milling force coefficients of side and end edge are calibrated by experiments.The milling force in helical milling process of C/E composites is predicted and compared with the experiment results.Taking the internal structure of C/E composites into consideration,the deformation of workpiece during the machining process and the change of end edge cutting thickness are analyzed.Based on the elastic foundation beam model,the axial force model is improved and verified by experiments.It is proved that the milling force model can predict the radial and axial milling force in helical milling process of C/E composites accurately.The influence of tool geometrical parameter on machining damage is studied.Helical milling experiments of C/E composites are conducted using flat end milling cutter and arc angle milling cutter with different shapes.The damage area is measured and the evaluation method is used to evaluate the burr,tearing and delamination damage.Combined with the helical milling process,the influence of tool shape on machining damage is analyzed.The tool wear of the edge and end edge is also analyzed.The effects of the velocity of the tool center,the trajectory of the tool and the cutting speed on machining damage are studied.Helical milling experiments of C/E composites are conducted with different feed speed,axial feed per orbital revolution and spindle speed.The milling forces are measured and analyzed.The burr,tearing and delamination damage is measured and evaluated.And then the effect of processing parameters on machining damage is analyzed.