| The dynamic performance of Computer Numerical Control(CNC)machine tool is an important factor affecting the comprehensive performance,which directly affects the machining efficiency and production safety of machine tool.Due to the flexibility of the numerical control processing technology and the complexity of working conditions,the dynamic performance monitoring of CNC machine tool has significantly complex characteristics.The key technology of dynamic performance monitoring of CNC turning process under multi-working conditions was researched using the complex system theory,and the results and conclusions as follows:(1)The complex origin of dynamic performance of CNC turning was analyzed from the perspective of complexity science.Cellular automata has the advantage of simulating complexity from the view of motion and evolution,On the basis of comparison and analysis of the wavelet packet decomposition energy entropy monitoring method and the deep learning of monitoring method based on large data,the fine monitoring method of turning dynamic performance under multi-working conditions was proposed based on cellular automata,and it is applied to monitor the vibration change sensitive position of turning in complex working conditions;(2)Taking the shaft parts CNC turning process system as the research object,the complex working condition model was added to the digital prototype of the process system and then the dynamic performance simulation test was carried out.The first six natural frequencies and mode shapes of the process system were obtained through the modal testing.The vibration response of shaft part turning process system under dynamic alternating load was obtained through the harmonic response test.The position and amplitude of the maximum amplitude occurring under different operating conditions were stored in the database,it finds out that the dynamic weak positions and the vibration sensitive points were concentrated on front end of spindle,the position of contact between tool holder and chuck and tail end of spindle,which provided a basis for the confirmation of monitoring objects and layout of the sensor networks of on-line monitoring;(3)In order to study the dynamic effects of complex operating parameters(spindle speed,feed rate,cutting depth,etc.)on sensitive point vibration,taking the sensitive point on the front of the spindle as the research object,Cellular Automaton(CA)model was established and the CA evolution rules were designed under the influence of process parameters.The simulation results were concluded that the maximum impact on the turning vibration is the amount of feed,relative to the spindle speed and cutting depth.The evolution trends of dynamic performance were concluded that the vibration intensity variability and the location variability of vibration sensitive points;(4)The dynamic performance monitoring system of CNC turning was developed by adopting Visual Studio2010 and MATLAB,which realized the data management function of dynamic performance simulation test in complex working conditions,CA simulation function of sensitive point location with the change of the working condition,and the experimental analysis of vibration test.The experiment of modal test and sensitive point vibration test were carried out for the NC turning process system,verifying the rationality and feasibility of the monitoring method.The modal test and sensitive point vibration test provided the data sources for regular maintance and precision improvement of machine tools,which also provided technical support for the steady state control of the performance and the healthy maintenance of the running state for the follow-up high grade CNC equipment. |
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