Research On Drilling Force Of CFRP And Design Of PCD Tool

Carbon fiber reinforced polymer(CFRP)is used widely in aerospace,industry,transportation,civil engineering,sports goods,etc.For its high temperature resistance,corrosion resistance,high modulus,high strength,low density,creep resistance,fatigue resistance,conductivity and heat transfer.However,its characteristics of anisotropy,high hardness and low interlayer strength,make it easy to occur delamination damage,burr and tear during drilling.Among them,delamination damage is the most important failure mode,which affects the strength of CFRP.And the generation of delamination is related to drilling force.In this paper,the drilling mechanism has been explore in depth.through the combination of the mathematical model of drilling force and the performance of CFRP material,and the theoretical model of drilling force is established,and provides a theoretical basis for the structural design of PCD cutters.The specific research contents are as follows:(1)The necessary parameters in drilling are considered comprehensively: the processing parameters,such as rotational speed and feed speed;the material parameters of CFRP,such as the angle of carbon fiber laying,elastic modulus and strength in all directions;the cutting tool parameters,such as the length of the transverse edge,the length of the main cutting edge,the large front angle,the normal front angle and the normal rear angle.In addition,some scientific theories are considered comprehensively that material mechanics,fracture mechanics,contact mechanics and composite mechanics,the mechanical model is built that drilling CFRP,in order to find the optimal tool parameters whose axial force is minimal.(2)The process of PCD bit drill drilling CFRP is simulated by ABAQUS,the axial force and delamination defects in the drilling process of different drill bits were compared and analyzed,and the optimal tool structure parameters,such as drill bit front angle,back angle and cutting edge length,are solved.(3)According to the tool parameters,PCD bit drill is designed.The structure of replaceable bit is adopted,and the air-breathing passage is added inside the drill to achieve internal chip removal.(4)The experimental platform is built and the orthogonal experiments are designed in order to explore the influence of processing parameters on the axial force.The results is compared that PCD bit drill and common twist drill drilling the CFRP,the results include the axial force of drill and surface morphology,to check the drilling quality of this drill.