| Carbon Fiber Reinforced Polymer?CFRP?is widely used in aviatio n,aerospace,energy and other top scientific and technological fields.Most of the research focuses on the design,moulding and performance testing of composites,while few studies focus on the secondary processing theory,process and quality evaluation o f composites.In addition,the blockade of CFRP precision machining theory and technology abroad has led to the long-term backwardness of China's composite material processing technology represented by carbon fiber composites.Based on the above problems,a series of studies are carried out in this thesis.The main work and conclusions are as follows:The influence of force and drilling parameters on drilling force during CFRP drilling is analyzed.Based on orthogonal experiment,an empirical formula of drill ing force for CFRP is established.Which is Fz=424.382·n-0.07f 0.275.The results show that the feed f has a great influence on the drilling force,and the tool failure under different feed conditions is studied.The results show that the tear and burr defects are easy to occur when the feed f is less than 0.1mm/r.When the feed f is 0.1-0,2mm/r,the quality of the hole outlet is obviously improved,and the side burr and tear defects are less.Finally,the chip shape of drilling and the damage degree of cutting edge are analyzed.The formation mechanism of hole inlet and outlet defects in CFRP drilling pro cess is analyzed.The existing methods of hole quality evaluation are s?mmarized,and the evaluation factors Fd and Fs of hole quality are established.Finally,the influence of drilling parameters?feed rate,rotational speed?on the quality of the hole is studied through specific experiments.The results show that the minim?m Fd and Fs values can be obtained by feeding f=0.15-0.2mm/r and rotating speed n=8000rpm,i.e.the optim?m orifice quality can be obtained.Based on the drilling quality,the tool structure is explored.Through drilling CFRP material with large apex angle and large passivation value,the drilling defects are analyzed in detail;Investigation and comparison of drilling tools manufacturer for composite material processing at home and abroad and selection of tools from some manufacturer were carried out.The influence of passivation value of bit top angle and edge angle on drilling quality and drilling force is studied by experiments.Finally,a new tool for CFRP drilling is developed based on the above research.The tool is used to drill CFRP material,and the drilling quality is evaluated. |
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