Study On Low-frequencyvibration Drilling Of Carbonfiber Reinforced Plastic/Titaniumstacks

Stack materials composed of CFRP(Carbon Fiber Reinforced Plastic)and Titanium has been widely used in modern high-tech components of the aircraft,this materials are usually adopts bolt or rivet connection,form the laminated structure,so that they can to reduce the quality of play to the advantages of different material at the same time,make the comprehensive performance of the optimal equipment,and carbon fiber composite materials and the performance of the titanium alloy large differences lead to laminated material hole is difficult.Conventional drilling cannot effectively crush and discharge high-temperature titanium alloy cutting cuttings,resulting in surface scratches and high-temperature scald of CFRP layer.Low-frequency vibration assisted drilling can reduce axial force,cut off titanium alloy chips,reduce the damage of titanium alloy cutting on carbon fiber composites,and effectively improve the quality of drilling.Therefore,the test platform of flexible low-frequency vibration assisted drilling is built in this paper,and the test shows that flexible low-frequency vibration assisted drilling can obviously improve the drilling quality.The main research results of this paper are as follows:1.A low-frequency vibration duplicating drilling prototype is designed and manufactured,which can realize variable frequency/variable eccentric mass to achieve variable axial excitation parameters.A set of PLC control platform is designed and built to realize force and displacement feedback adjustment and achieve automation of drilling process.2.The mechanical model of low-frequency vibration assisted drilling was established,and the nonlinear average method was applied to analyze the drilling process of low-frequency vibration drilling of titanium alloy holes,illustrating the nonlinear characteristics of low-frequency vibration drilling.The amplitude-frequency characteristic curve of no-load/working state was drawn through frequency sweeping test,and the stable working area of the equipment was found to be 33-41 Hz.3.Using the designed low-frequency vibration drilling system,the drilling test of carbon fiber composite/titanium alloy laminated material was carried out through vibration measurement system,temperature measurement system and non-contact laser measurement system.The axial drilling force,exit chip temperature,chip morphology and hole diameter were analyzed.The research shows that low frequency vibration can effectively improve the drilling quality,and can reduce the drilling temperature by 29% and the drilling force by19% compared with ordinary drilling.However,unreasonable vibration intensity will further damage the carbon fiber layer,and the minimum vibration intensity is the most reasonable vibration intensity to achieve the breaking condition.