Research On The Drilling Temperature And Hole Quality In Drilling Carbon Fiber Reinforced Composite

Carbon Fiber Reinforced Composites have been widely used in aerospace, automotive, sporting goods and other fields because of their light weight, high strength, good design, chemical corrosion resistance, excellent electrical, resistance to erosion and easy molding, etc. The common machining methods are classified into conventional machining and un-conventional machining. In conventional machining, drilling process costs above 50 percent of total cutting amount and it is the most important form of cutting process. However, Machining composite materials is a rather complex task owing to their laminated structure, anisotropy and lower coefficient of thermal conductivity, and it exhibits considerable problems in drilling process such as the easily accumulated of heat, the severely wear of drilling tools, delamination, thermal degradation, etc, which will seriously affect the durability of the tool and borehole quality.According to the difficulty of machining CFRP, the experimental studies on drilling temperature and holes quality have been carried out in this thesis. The main works of this thesis are as followed:(1) Research on the basic theory for drilling. Mainly includes the chip deformation and chip formation analysis, analysis of the basic theory and its influence factors of the cutting heat and the cutting temperature, cutting force.(2) This dissertation analysis the cutting temperature measuring methods in present and adopts embedded thermocouple method combine LabVIEW software to get the temperature signal. A measure temperature platform for drilling CFRP is built. By orthogonal test method to analyze the effects of spindle speed, feed rate, drill tool angle and tool diameter on drilling temperature. The temperature drilling empirical formula is established by the SPSS software and the verification test are carried out on drilling CFRP.(3) Research on various defects in drilling CFRP and the defect formation mechanism model are established, in order to analyze the reasons for the formation of various defects. The effect of spindle speed, feed rate, drill tool angle and tool diameter to holes quality is analyzed by using single factor experiments. By use of orthogonal array experiments based on Taguchi method, the major factors which have the greatest influence on the hole surface roughness, peel-up delamination and push-out delamination are studied to get the optimized combination of cutting parameters aiming to decrease them to minimum. The morphologies of hole’s wall is observed by SEM and the effect of drilling temperature to holes quality is also analyzed. Application of artificial neural network technology. A drilling temperature prediction model, with spindle speed, feed rate, drill tool angle and tool diameter as the input vector and drilling temperature as the target vector, is established by MATLAB neural network toolbox. Meanwhile, a hole quality prediction model, which the drilling temperature as one of input vector, is also established.