Research On Reliability Technology Of Machining Center And Its Functional Units

Because of the low reliability, high-grade machine tools basically depended on import for a long time, at the same time, domestic machine tools barely limited to lower-grade products. Machine tools'reliability directly effect customs'using condition and purchasing desire, so the low reliability not only greatly influence normal operation of equipment, but also increase costs of manufacturing enterprises and customs, more importantly, it effects the confidence to using domestic machine tools. Although the MTBF of domestic machine tools had increased from 200h to almost 500h in last 20 year's technology research, domestic machine tools still have a high rate failure which compared to import domestic machine tools. This paper in base of the National Major Scientific and Technological Special Project for"High-grade CNC and Basic Manufacturing Equipment", taking domestic machining center as research object, and had a deep research on reliability technology of its typical functional units. We hope this research results could promote the reliability of typical functional to increase machining center's reliability.First of all, this paper was base of some machining center's failure dates investigation, and comprehensively mastered domestic machining center's reliability present situation, the investigating result showed that the failure rate of machine tools was extremely high in the earlier using period, so we distinguished the failure stages through failure rate bathtub curve, defined the NC machine tools'early failure, confirmed the early failure period by the quantitative research of failure rate bathtub curve, then, the concept of early failure elimination technology was put forward, forming reasons and elimination mechanism were researched, at last, we made the elimination process of early failure, as well as narrated detailed the content and implementation method of early failure elimination technology.Secondly, this paper researched the early failure elimination technologies'application of NC rotary table. After find out the structure, function and performance index of NC rotary table, the theoretical analysis about NC rotary table's potential failures was the foundation to design reliability enhancement test project, testing profile's establishment and accelerate stresses'selection were mainly studies. Finally, analyzed failures occurred in reliability enhancement test, found out failure reasons and gave availably improvement measures to elimination failures, enhance the reliability as well.At last, the paper researched the reliability technology of tool magazines. Tool magazines had the highest failures in purchased components, the aim of researching its reliability technology was to validate tool magazines'reliability matched the design's need. After analyzed the GO method model of tool magazines, the weakness was found and established reliability acceptance check test method, confirmed acceptance check project, the judgment was gave which based on the test results. The application of tool magazines'reliability technology could standardized the process of purchased components acceptance check, reflected failures to suppliers, and supervised them implement quality improvement.Functional units'reliability is the foundation of the machine tools'reliability. Machine tools'reliability could effectively improve none but reliability of functional units has guarantee. The research result shows that the reliability technology of typical functional units can effectively increase and control the reliability, finally, to enhance machine tools'reliability.