Study Of Drilling Force And Hole Quality In Drilling CFRP Process On Complex Helical Drill

Carbon Fiber Reinforced Plastics(CFRP)have been widely used in airplanes,communication and transportation,sport equipment and textile owing to light weight and high stiffness-to-weigh ratios,fatigue resistance,and good heat resistance.The CFRP mainly adopts riveting and bolt connection to connect the structure,which requires a large number of connecting holes which are mainly processed by drilling.A series of machining defects appear in drilling CFRP including poor quality which has a serious impact on the performance and lifespan of CFRP.Drilling force is a important factor to influence the quality of drilling,so study of drilling force and hole quality in drilling CFRP process to practical production has a important value and significance.A mathematical model of drilling force is established for complex helical drill and the experiment of drilling CFRP with complex helical drill is carried out.Finally,drilling parameters of the CFRP are optimized.The main works have been done as follows:(1)Introduce the definition and classification of CFRP and its applications in various fields.Summarize research status in drilling process at home and abroad.Analyze the characteristics of the complex helical drill and grinding principle.(2)Establish the mathematical model of drilling force for complex helical drill in consideration of characteristics of the complex helical drill point and the material properties of CFRP.(3)Grind complex helical drills with a variety of different geometries to carry out drilling experiment of CFRP.Analyze the influence of different geometric parameters and process parameters of complex helical drill on the thrust force and torque to verify the correctness of the mathematical model of drilling force.(4)Analyze the formation mechanism of the burr,tearing and delamination in the process of drilling CFRP in detail.Establish the formula between the tearing length,burr length and thrust force.At last,establish the mathematical model of the critical thrust force about delamination.(5)Optimize drilling parameters of the CFRP taking consideration of the maximum removal rate of material as the optimization target.Establish the empirical formula between the thrust force,length of burr and tearing and drilling parameters.Finally,obtain the optimal tool geometric parameters and process parameters by MATLAB.