Research On Chatter Reliability Of Turning Processing System

As a form of common vibration of the machine tool, chatter restricts the development of high precision and efficiency of machine tool industry. Chatter also accelerates abrasion of cutter and shortens the life of tools, therefore, the reliability of turning processing system is the key of the machine tool research. With the support of NSFC of China, the chatter reliability of turning process system is studied. In this paper, the main content includes:1) The chatter mechanism of turning processing system is introduced. The mathematical model of SDOF are built and the regenerative chatter of turning processing system is defined as a kind of self-excited vibration of delayed displacement feedback, the expression of limit cutting width of turning processing system is deduced. Stability lobes diagram is given by a concrete example of machine tool. The influence of structure parameters on the stability lobes diagram is also studied. 2) Stochastic stability lobes diagram (SLD) model of turning chatter vibration is proposed while the structure's parameters obey a certain distribution. The FRF diagram and SLD, of the lathe with uncertainty parameters is shown by a example and the reliability of turning processing system is solved by Monte-Carlo method at the specific processing parameters. Compared with the result of traditional SLD, the stochastic SLD can reflect the reliability of the turning processing system.3) Aimed at solving the problem of the chatter reliability, the methods of AFOSM and fourth-moment are studied. The specific calculation of two methods are given, the samples of reliability at the specific processing parameters and the graphics of reliability with the change of processing parameters are shown by a case, and are respectively compared with the result solved by Monte-Carlo method, it is concluded that moment method is more practical than Monte-Carlo method with high precision and small computation in practical engineering.4) Aiming at solving the problem of the influence of the structure's parameters on turning processing system, the Monte-Carlo method to solve the sensitivity of turning processing system are studied. The steps of solving the sensitivity of turning processing system are given and the concept of sensitivity factor is also introduced; The partial derivatives of the random variables are shown and the meaning of values is illustrated by a case. By calculating sensitivity factor, it is concluded that the modal quality have the greatest influence on the system's reliability and the conclusion provides the basis of theory for the turning processing system.5) To solve the source of data about the lathe, the test is made to get the structure parameters which include the mean and standard deviation. Taking the Lathe CJ0625 as the experimental object, this paper introduces the experimental equipment, gives the concrete method of modal parameter identification; Using the method of component analysis to analyze collected data which is from the frequent test about x direction of lathe, and then get the structure parameters. At last. We can get the mean and standard deviation of modal parameters by observing the statistical samples.