Body-in-white Multistage Assembling Deviation Diagnosis Method Research Oriented To Multi-line Production Process

Production lines which are designed for producing more than300000single bodies per year are usually devised in multi-line mode to achievehigh quality with relatively low cost. Body-in-white assembly process iscomplicated and performed in multi assembly stations. In this process, partdeviation and fixture deviation couple with each other and the finalcomprehensive deviation accumulates as assembly process goes forward.Sources of deviation are numerous in this multiline manufacturingprocedure and the underlying causes for quality problems in different partsvary from each other. The capability to accurately orientate sources ofdeviation plays a key role in improving the quality of body-in-white inmulti-line manufacturing process.In this paper, Through the researches on types and characteristics ofbody-in-white multi-line production process, we establish an objectiveevaluation method of body-in-white sizes difference for multi-lineproduction process on the basis of data characteristics of key sizes. Afterintroducing the theory of "two kinds of quality diagnosis" which make acomparison between assembly quality in different levels, we perform afault diagnosis method on body-in-white assembly. Moreover, this methodis applied to define specific sources of deviation in the malfunctionedassembly system and achieve rapid diagnosis of body-in-white deviationsource. Thus we strengthen the control of the quality in multi-lineproduction process. In this paper, the main research work is as follows:（1） Quality difference evaluation method for multi-lineproduction processIn this part, the multiline mass production system with a single kind of product is studied and quality control scheme is proposed forbody-in-white production. Based on the quality requirements, qualitydifference evaluation method for multi-line production process isconstructed.（2）Multistage assembling deviation source diagnosis methodsfor multi-line production processIn order to diagnosis the multistage assembly process deviationsource of body-in-white, we first divide assembly production process intomany parts according to the position of measuring stations, such aswelded-parts, subassembly, assembly. Then the theory of "two kinds ofquality diagnosis", which evaluates different production lines andassembly levels quality to distinguish the quality responsibility at all levels,is introduced to diagnosis main deviation happens in which assembly level.So the scope of fault source lookup is narrowed.（3）Case study and verification for multistage assemblingdeviation source diagnosis schemeBased on the researches above, the method is applied to abody-in-white multi-line production process in SGMW on sizes deviationproblems of two parts named Front baffle plate and Tail beam. Deviationin assembly level is orientated rapidly and product quality is successfullyimproved. Those cases verified the effectiveness of the deviation sourcediagnosis method proposed in this paper.In this paper, we have studied the deviation of source diagnosismethod, and successfully applied it in an automobile factory to solve realworld problems. This method can be further applied for deviation sourcediagnosis in other kinds of thin-walled parts multistage assembly process.