Modeling lathe dynamic system in terms of estimated dampening coefficient of autocorrelation function of oscillations

Part machining on the lathes with automated tools is a complex process that depends on the properties of the lathe dynamic system. Oscillations in processing the main parts determine the dynamic quality of the lathes, quality of the surface layer and resistance of the cutting tool, therefore, it is necessary to identify the methods to control the operation mode. Increased efficiency of the process is provided by the forced cutting modes, which can lead to the deterioration of processing quality and premature wear of a cutting tool. Theoretical definition of rational cutting modes causes certain difficulties, so the experimental search for a solution to the problem is most urgent. In order to select rational cutting modes on the lathes and grinding machines, it is proposed to use the stability margin of the lathe dynamic system (DS), which should be determined from the transfer function of DS using the autocorrelation function (ACF) of oscillations. A condition for identification of the lathe DS is a preliminary identification of ACF, which can be implemented using oscillation records during cutting. Pre-filtering of oscillations is carried out to exclude low-frequency range containing frequencies caused by oscillations of lathe system elements and to save frequencies associated with the cutting process. Cut modes are assigned to the highest stability margin, which ensures high surface quality. There is an unambiguous ana-lytical relationship between the oscillation index and the damping coefficient of the ACF, which makes it possible to calculate the $\alpha$ coefficient, by the value of which it is possible to estimate the stability margin of the ET in different cutting modes and select the most appropriate one. Studying the lathe oscillations in processing high-precision parts makes it possible to control the technological mode, using the oscillation level as one of the indicators of its quality.