Vibration Signal Analysis And Control Of Machine In Drilling Carbon Fiber Composite Material

Carbon fiber reinforced matrix composite has the performance advantages such as:the higher strength and modulus,which make it widely used in aerospace,chemical machinery,medical equipment,sports equipment and other fields.With the complexity of parts structure,CFRP needs to be drilled,milled,grinded,and other machining.However,due to the high hardness of CFRP,especially its layer structure,it was easy to cause vibration during the drilling process,and lead the drilling surface appear significant dent and delamination defects.Therefore,the analysis and control of vibration in CFRP drilling process were particularly important.According to the phenomenon of drilling vibration,theoretical analysis and experimental research focus on the vibration drilling,drilling force and drilling quality,the main works of this thesis are as followed:(1)Based on the analysis of drilling system differential equations and the influence factors of vibration effect,including the feedback effects of drilling vibration,drilling force and hole wall roughness,and the effects of the drilling material,drilling tools,drill geometry parameters and cutting parameters on the drilling force.Study on the analysis methods of vibration signal,then designed a set of cutting vibration signal test system based on Labview virtual instrument,included data collection,calculation,analysis and waveform display.The system can achieve the elimination of trend term,filtered the signal denoising,the calculation of effective value and the power spectrum density.(2)Build the vibration and drilling force tesTiNg experimental platform,then analyse the effects factors of vibration and force.The design experiment including:Firstly,a modal test for the analysis of natural frequency;Second,tesTiNg the spindle vibration of different processing stages,in order to analysis the vibration source;Thirdly,analyze the influence of process parameters on the vibration and drilling force and the quality of drilling hole,then by the range analysis and variance analysis of orthogonal experimental results,with the optimization objective of the vibration drilling,drilling force and hole wall roughness,obtained the optimal combination of the spindle speed,feed rate,drill angle and the material.(3)Discussion of the vibration control method,analysed the active control,passive control and process parameter control strategy.Through the CFRP drilling experiment,compared the cutting performance of traditional twist drill and three blade twist drill,brazed diamond core drill,the results show that:increasing the number of cutting edge,the force of unit length was reduced,drilling vibration amplitude decreased,and the drilling force was evenly distributed on core drill can effectively control the drilling vibration.