Research On Reliability Evaluation With The Method Of Considering The Failure Hazard For Domestic CNC Lathes

Advanced CNC machine tools and basic manufacturing equipment is the foundation to achieve the modernization of manufacturing technology and industrial. Developing the advanced CNC machine tools and basic manufacturing equipment has the global and strategic significance. And reliability is the critical indicators to the machine tools quality. For e.g.:The domestic heavy CNC lathes'MTBF is around 300 hours which has significant gap between the imported machine tools. Improve the reliability of the domestic CNC lathes is our urgent task now.Reliability evaluation of CNC lathes was used to evaluate only one aspect of CNC lathes, and was lack of a comprehensive evaluation on the overall CNC lathes. This paper takes a series of studies on domestic CNC lathe, through the studying of the whole machine and machine subsystems which includes the hazard analysis, fault distribution model and the MTTFF distribution; we established evaluation system for the overall CNC lathes. And I researched on reliability evaluation with the method of considering the failure hazard for domestic CNC lathes.First collected a large number of a series of domestic CNC lathes reliability data. Make the fault location, model analysis according to the principle of fault classification Failure Mode Analysis. Then use the CNC Workbench system as an example to set up MTBF and MTTFF distribution model, introduced the concept of harm coefficient, and calculated the equivalent failure rate for the Workbench subsystems. Make the comprehensive evaluation of the subsystems'reliability. Classify the results of the assessment according to score values. Finally, set up the MTBF and MTTFF distribution model through model selection, parameter estimation and model testing. Calculate the equivalent failure rate for the whole CNC lathes. Make the comprehensive evaluation of the whole CNC lathes through the MTBF, MTTFF and equivalent failure rate. And classify the results of the assessment according to score values which make the evaluation more objective, scientific and rational.