关键词: 数控机床, 元任务, 模糊集, 可靠性分配

Abstract: Aiming at the dynamic characteristics of Computer Numerical Control(CNC)machining process, a task-based reliability allocation method based on the research limitations of existing reliability allocation of CNC machine tools was proposed by combining the phased-mission system theory and the task reliability principle. The mission section hierarchical model of CNC machine tools was established according to the actual situation of all the tasks. To analyze and research the meta task level of CNC machine tools, five important impact factors of reliability allocation including run time, importance degree, complexity degree, technical level and working condition were identified. By fully considering the suggestions of many experts and the risks in CNC machine tools research and development process, a function to decide the fuzzy truth value was defined and a way to determine the membership degree was given through fuzzy set theory. The reliability allocation indicator system, weights and fuzzy evaluation matrix of meta task were established. An example of main processing meta-task group was taken to prove the availability of the method.

Key words: CNC machine tools, meta task, fuzzy set, reliability allocation