The Research And Application Of Remote Fault Diagnosis Technology For CNC Machine Tools

Compared with foreign advanced level, we have a large gap in the designing, manufacturing, assembly and maintenance of CNC machine tools, resulting in insufficient levels of product reliability and many failures, etc. The majority of high-end CNC machine tools rely on imports, which have seriously hampered the domestic independent development of modern manufacturing and defense industry, and thus, it is very important and necessary to improve the reliability of domestic CNC machine tools and CNC system.In order to reduce the faults of domestic CNC machine tools and improve its reliability level, we must do the best in the work of fault monitoring and diagnosis, while the reliability engineering was carried into the fault diagnosis process, to seek a breakrhrough in the theoretical and practical aspects. In this paper, in the background of the national "high-end CNC machine tools and basic manufacturing equipment" major science and technology subject "million units of CNC machine tools supporting domestic CNC system application engineering", we carried out the research of fault diagnosis technology and remote fault diagnosis system of CNC machine tools. The main contents include the following two parts:Firstly, a comprehensive diagnosis model of the fault tree was proposed, which integrated qualitative and quantitative analysis, and gathered the advantage of fault matching and status information assessment, in addition, partial failure traceability was done. It divided into three steps: ①failure matching. Fault tree was used as the main matching line, then we looked for the target fault tree node which matching the given failure symptom. All the nodes which below this node were got, and each of the end of event corresponding to the nodes were all likely to be the cause of failure, which was called failure possible set. ②Assessment of NC machine tools status. Take each event of the failure possible set as research subject, combined with the normal data of the standard knowledge base for comparison analysis, and according to the processing result of operation status information by the multi-information fusion theory, the failure possible set was reduced to just one or few causes of troubles in the collection, which was called failure determination set. ③The reliability analysis model of the k/n(G) Markov repairable system with different units was built, the calculation methods of reliability were studied using Markov processes in the model.Secondly, a remote fault analysis and diagnosis system was established, the platform for operating status data collection, transmission, storage and application of CNC machine tools was built combined with enterprise. Terminal fault diagnosis software was developed. The following processes were included: ①Studying and determining the items and formats of the necessary operating status data for monitoring the CNC machine, and the transmission and storage method of remote data. ②Developing the fault diagnosis system software. Troubleshooting and analysis was done by the application of machine running status data. The demand for project analysis, the way of input and output, working principle, the mathematical model, interface design and implementation of the programs were introduced in this part.