Dynamic Analysis Of Faults In Rolling Linear Guides

Rolling linear guides are an important part of the CNC machine feed system and play a decisive role in the quality of machine tool processing.A faulty rolling linear guide system not only can affect the accuracy and quality of the workpiece with a certain amount of noise but also can damage the machine components or even cause a safety accident.The research on the fault rail system can extract the fault characteristics to prepare for the predictive maintenance and fault diagnosis.Therefore,it is very important to carry out the establishment of the rolling linear guide fault model and the fault dynamics analysis.The main research contents of the thesis include:(1)It is studied that the coupling relationship between the wear amount of the rolling linear guide and the elastic deformation of the ball.The influence of the wear on the dynamic characteristics of the rolling linear guide is analyzed.Based on the Hertz contact theory and the Archard wear model,the relationship between the running distance and the wear amount of the rolling linear guide is obtained.The static model considering the change of the wear amount is established and the influence of wear on some parameters is analyzed.A piecewise nonlinear dynamic model is established.The effects of wear on the vibration characteristics of the rolling linear guide system are analyzed using the amplitude-frequency characteristic curve,the bifurcation diagram and the waterfall diagram.(2)Dynamic analysis of the rolling linear guide system.Based on the relationship between the length of slider and the diameter of balls,the number of balls driven will be different,and the transition curve at both ends of the slider will change the elastic release amount of the ball.At the same time,considering the initial phase of the different rows of balls establish the sliding of the rolling linear guide system.The dynamic model of block horizontal motion is verified by experiments.The effects of the slider length,the change of initial phase and the type of external excitation on the vibration response curve are analyzed.The influence of the change parameters on the dynamic response amplitude is analyzed.The parameters causing the nonlinear phenomenon are discaussed.Effects about non-linearity after the slider movement are discaussed.(3)The pitting characteristics of rolling linear guides were studied.Based on the dynamic model of horizontal movement of slider in Chapter 3,two kinds of pitting models are established.The elastic release of balls will change when the ball through the pitting defect.According to the Hertz contact theory,the pitting dynamic model of the rolling linear guide is established.The Runge Kutta method is use to solve.The variation of the elastic release and internal force caused by different types of pitting defects on the linear guide are discussed.The effects of different pitting defects and different slider lengths on dynamic response are obtained by time domain,phase and spectrogram.Through the research of this paper,the rolling linear guide dynamics model with wear and pitting is established respectively,and the influence of wear amount and pitting corrosion on the vibration characteristics of the rolling linear guide system is analyzed respectively.The obvious fault characteristics can be extracted compared with no fault.It has important guiding significance to online monitoring of rolling linear guides.