| The BIW manufacturing dimension quality directly affects the automobile appearance and performance.Through the development of automobile manufacturing industry,the control and improvement of BIW manufacturing dimension quality become an important work for automobile manufacturing enterprises and a key point for academic circles and automobile enterprises.This article focus on the process analysis,studying a method of dimension quality analysis and improvement covers the whole stages of automobile body manufacturing which also can be used in the commissioning stage and production stage and then to improve the BIW manufacturing dimension quality and to meet the requirements of customers.In BIW manufacturing process,the statistical conditions in each period is different,the dimension quality control process needs different statistical process control theory to satisfy the needs of the BIW manufacturing process.In order to solve the problem the article presents a control method which combined the ICM(debugging capability index)and EWMA(exponential weighted moving average).In the situation of insufficient statistical samples during the commissioning stage,the measurement point which is not met the ICM index needs improvement.Through the M measurement values which has been improved to calculated the united variable(The Improved Average)and(The Improved Standard Deviation).The EWMA control chart apply to the situation of sufficient statistical samples during the production stage,the double line equation with uncertain factors is suggested and make joint variables to form intermediate variables into the equation and then realize the construction of improved EWMA control chart.Based on the combination control method and quality improvement methods and monitoring plans combined in different periods,the article present a dimension quality improvement mechanism,in order to form the basis which composed by theoretical framework and practical.This mechanism is constructed using time series combined control method the quality improvement method with three-stage,including characterizing the problems,conforming the reasons and finding/suggesting/solving procedures.The gradually run of the mechanism will be the theoretical basis of BIW manufacturing dimension quality improvement in all the producing periods.In this application,combine with the manufacturing process of Brilliance BIWs,the dimension quality improvement mechanism of BIW manufacturing in all the periods will be built through the measurement data.And then the united control method of ICM and EWMA would be testified.The evaluation results indicate the process control mechanism of BIW manufacturing dimension quality could meet the requirements in commissioning and production periods and provides a feasible method for the actual production process. |
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