Research On The Defect Of Surface Delamination In Milling Carbon Fiber Reinforced Composite

Carbon Fiber Reinforced Composites have been widely used in aerospace,architecture,machinery,medicine,sports and other fields because of their light weight,high strength,good design,chemical corrosion resistance,excellent electrical,resistance to erosion and easy molding,etc.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 milling process such as easy accumulation of heat,the severe wear of milling tools,delamination,thermal degradation,etc,which will seriously affect the durability of the tool and milling surface quality.According to the difficulty of machining CFRP,theoretical analysis and experimental studies on the defect of the surface delamination in milling CFRP have been carried out in this thesis.The main works of this thesis are as followed:First of all,the reasons that lead to surface defects such as delamination,tearing and uneven during the milling of CFRP are analyzed.The effect of the different direction of fiber,ways of milling,cutting parameters and mills with different structural parameters on the suface delamination in milling CFRP is studied which lay a foundation for the experimental studies.Secondly,research on the effect of ways of milling and cutter structure on the suface delamination in milling CFRP.Milling experiments of CFRP are carried out for comparative analysis on the surface delamination under different ways of milling and to study the effect of the number of teeth and helical angle of milling cutter on the suface delamination.And some advices are given out on how to choose the ways of milling and mills reasonable.Thirdly,research on the effect of direction of fiber on the suface delamination in milling CFRP.According to the structure and the anisotropy of mechanical properties of CFRP,theoretical analysis of the formation of the suface delamination of different direction of fiber have been conducted,and milling experiments of CFRP are carried out to analyze the suface delamination of different direction of fiber and study the formation rule of the suface delamination of different direction of fiber.Some advices are given out on how to choose the direction of fiber reasonable.Finally,research on the effect of cutting parameters on the suface delamination in milling CFRP.Single factor analysis is used to analyze the effect of cutting speed,feed per tooth and depth of mill on the suface delamination.And by use of orthogonal experiments,the major factors which have the greatest influence on the suface delamination are studied.With the optimization objective of the suface delamination the optimal combination of cutting parameters is obtained.The suface delamination empirical formula is established by multiple linear regressions using SPSS software.Besides the effect of cutting parameters on surface roughness is researched,the effect of milling force on the surface roughness and the suface delamination is also analyzed,and the milled surface topography is observed by SEM to analyze the contacts and differences between the surface roughness and the suface delamination.