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Fault Diagnosis System For CNC Machine Tool Based On Fault Tree Analysis

Posted on:2009-11-09Degree:MasterType:Thesis
Country:ChinaCandidate:D P DiFull Text:PDF
GTID:2121360248454327Subject:Mechanical Manufacturing and Automation
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Because each kind of different discipline new technology's mutual seepage, the traditional mechanical engineering various domains' boundary becomes fuzzy, the intelligent technology, the sensing technology, the information technology and machinery's union, has produced machine, the electricity, the fluid collection in a body's numerically-controlled machine tool, expands, the function day by day along with its application domain also because of the modern user's request, but is getting more and more complete and is formidable. After the numerically-controlled machine tool breakdown occurs, how to diagnose rapidly crashes the reason and solves the problem to make it to restore normally, is the urgent need of raising the numerically-controlled machine tool use efficiency. But, on our country existing numerical control system variety is extremely many, also has the domestically produced various grade of numerical control system, also has from various countries system,such as FANUC O-TC, O-TD systems, Simens 810,820,880 systems, Mitsubishi system, Central China numerical control and so on. Each system complex degree is irregular, the function varies, the structure style does not seek diversely. In service process, regarding such complex, synthesis system, fault diagnosis whether to follow certain rule and the method, how to catch the crux to be in many fault phenomena.In the foundation of comparing domestic and foreign numerically-controlled machine tool fault diagnosis method good and bad points', through to the CNC machine tool fault example analysis, using fault tree module parsing algorithm to Fanuc the 0i numerical control machine tool's principle of work, the breakdown phenomenon carried on the quantitative analysis to obtain has gone against the event failure probability, the bottom event structure importance, the probability importance; Uses based on the object-oriented method and the expert knowledge intelligent diagnosis method, solves the smallest cut-set with the Fussed law, the large-scale complex fault tree, decomposes into the relatively independent many sub-trees; Thus transforms the domain expert's experience knowledge as the diagnosis system's expert knowledge, to the numerically-controlled machine tool typical breakdown establishment fault tree, carries on the breakdown qualitative analysis through its smallest cut-set, has determined system's inference method. Makes the demand analysis to the CNC machine tool failure diagnosis expert system, including the functional analysis and the non-functional analysis, and makes the active flow chart to each functional module; Finally makes the pipeline type topology the system design, and applies the fault tree analytic method in the failure diagnosis expert system analysis inference mechanism. In the article elaborated the system development data management pattern, including the data storage form, the database connection, carries on management operations and so on increase deletion to the database, to be related the tool and face the object programming; Finally, introduced expert system diagnosis inference realization.The diagnosis expert system of CNC machine tool is composed knowledgebase, inference engine, database, man-machine interface, explanatory program, and diagnosis result and so on. Diagnosis knowledge, which is expressed with production rules and Object-Oriented paradigm from the knowledgebase. According to initial data that user put into database and knowledgebase, inference engine make proper diagnosis result in the end, experimentalism to validate that the CNC machine tools fault diagnosis expert system was efficacious. The method of fault diagnosis of CNC has great practicability and value of generalizing.
Keywords/Search Tags:CNC machine tools, Fault tree analysis, Minimum cut set, Expert system
PDF Full Text Request
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