Research On Dynamics And Optimization Of Time-varying Structure For CNC Feed Drive Mechanism

CNC feed drive system is an important part of CNC machine tool, and itsinherent properties and dynamic response relates to the operational performance ofthe whole machine tool. With the improve of cutting feed speed and feedacceleration, on the one hand inertia effect is increased remarkablely, which has astrong impact on the working performance and working life of CNC machine tooldue to resulting vibration and noise, on the other hand because of the high speed andlightweight requirements, the elastic deformation of machine tool parts has beenunavoidable, which has greatly changed the dynamic properties of traditional idealmachines. Therefore，research on the dynamic characteristics of CNC feed drivesystem has an important signification to improve the working speed, workingaccuracy and working life of CNC machine tools.But the current researches on dynamic analysis usually consider the machinetable on one fixed position (mostly on the middle position), which can’t reflect thereal time dynamic characteristics of the feed drive system in the operating process.This method will inevitably lead to the deviation of control performance and depressthe working accuracy of machine tool. Aiming at the problems of the change ofdynamic characteristics of CNC feed drive mechanism, this thesis carries out theanalysis of the dynamic characteristics of the rigid-flexible coupling system andexperiment research. The main work includes:(1) Using finite-lumped parameter method, a rigid-flexible dynamic model ofCNC feed drive system is built through the softwares of Solidworks, Patran\Nastran,and Adams.(2) The worktable position and the mass of load are changed to simulate thereal-time work condition, and the vibration module Adams/Vibration is used toanalyze the natural vibration frequencies of the model.(3) Using data acquisition instrument and model analysis software, the changerules of the natural vibration frequencies are measured which is compared with theexperiment results.(4) Use the methods of topology and parameter optimization to optimize the system structure, and contrast the results of before and after optimization.