基于驱动电机电流信号的车削颤振在线监测方法分析-analysis of on-line monitoring method of turning chatter based on current signal of driving motor.docxVIP

AbstractChatter is a self-excited vibration that occurs during machining operations and becomes a common limitation to productivity and part quality. Chatter occurrence also has several negative effects, such as excessive noise, machine tool damage, disproportionate tool wear, damage of the tooling structure and the spindle bearing. For these reasons, chatter avoidance is a topic of enormous interest for many researchers who have focused on the solutions to the problem of chatter. But most of the chatter detection methods can only be used in laboratory, and be difficult to use in practical production. Hence, in order that the on-line chatter detection technique can be applied to manufacturing production, further research need to be done.In order to realize the engineering application of chatter detection technique, a method of chatter detection based on motor current signal is proposed. By determining the experimental program, experiment design of chatter detection in NC vertical lathe was finished. The current signal monitoring experimental system was established, and a serires of experiment was completed.The response characteristics of different motor current signal to the cutting state was analyzed. Mode of spindle and feed drive system was established. Experiment was designed to identificate parameters of spindle and feed drive system. Rapid assessment method was given to judge the applicability of the proposed chatter detection based on current signal and how to choose the motor current which is more sensitive.According to the low signal to noise ratio of current signal, feature extraction was carried out in the time domain and time-fraquency domain. The feature vector of current signal used for chatter detection is constructed on the basis of empirical mode decomposition. In addition, acceleration signal of tool is taken as reference and used to compare with the results from current signal.In order to detect chatter accurately, a support vector machine is desi