FMEA analysis based comprehensive reliability allocation method for numerical control machine tool

Abstract

The invention discloses an FMEA analysis based comprehensive reliability allocation method for a numerical control machine tool, and belongs to the field of mechanical system reliability analysis. According to the method, the comprehensive reliability allocation for a system is carried out based on an FMEA three-order conversion function and a Copula function, so that the problems of a single consideration factor, only capability of regulating reliability differentiation degree of high severity or failure frequency, and the like in an existing machine tool reliability allocation method are solved; the conversion function in the method is simple in form and easy to understand and operate, covers the advantages of a conventional index conversion function and extends reliability differentiation degree regulation capability of a low interval and a medium interval of an FMEA analysis result; the method considers influence of various allocation indexes and fault correlation effects at the same time, and has the characteristics of good integrity and convenience for engineering application; and compared to a conventional method, the subsystem reliability obtained by analysis with the method is lower, the manufacturing and processing cost requirements can be better lowered, and very important engineering value is achieved.

Description

technical field [0001] The invention belongs to the field of mechanical system reliability analysis, and in particular relates to a method for comprehensively assigning reliability of numerical control machine tools based on FMEA analysis. Background technique [0002] Mechanical reliability distribution is the process of assigning the reliability index of the whole machine system to the subordinate products at all levels from top to bottom according to certain principles and methods, and finally reaches the reliability index of the whole machine system. The reliability of the mechanical system is within a certain range. The extent depends on the rationality of the reliability index allocation process at the initial stage of design; [0003] As the main equipment of the manufacturing industry, the reliability of the CNC lathe plays a key role in the development of the manufacturing industry; due to the complex structure and various failure modes of the CNC lathe, the reliabi...

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Problems solved by technology

[0003] As the main equipment of the manufacturing industry, the reliability of the CNC lathe plays a key role in the development of the manufacturing industry; due to the complex structure and various failure modes of the CNC lathe, the reliability distribution results in the early design stage are often unreasonable or insufficient in credibility phenomenon, which in turn affects the efficiency and life of machine tools; therefore, it is very important to discuss how to reasonably allocate or redistribute CNC lathes;

[0004] CNC machine tools can be regarded as a typical series system. For the reliability distribution of series systems, there are currently the average distribution method, the direct distribution method based on FMEA, the exponential conversion function distribution method based on FMEA, the comprehensive distribution method, and the fuzzy distribution method. However, different theories have their own advantages and disadvantages; for example, compared with the average distribution method based on FMEA, the index transfer function distribution method based on FMEA has enhanced the high severity and high The reliability discrimination degree of failure frequency, but in engineering practice, the severity and failure frequency of most subsystems are distributed in the middle range (FMEA evaluation value is 5-8), this method is not well applicable

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