Research & Application On Statistical Tolerance In Manufacturing Process Quality Control

The product quality and manufacturing accuracy has always been a weak link in the chain of the mechanical engineering for it to take part in the global market competition. The present high requirements of the high technology industry for the manufacturing precision have put the mechanical industry in China steps behind in the product quality competition. To address this, the statistical tolerance control technology plays a key role, not only for its competency in the design the product geometric design, but also for the undeniable effectiveness in the statistical quality control and test in the manufacturing process.This paper discusses the statistical tolerance control technology oriented on the part level and the fit level through the statistical method to meet the target of the quality control. The Application of the technology combined with the characteristics of the modern manufacturing technology is also discussed.The paper first describes the status quo of the statistical technology and concludes its method at home and abroad. It then shows the target, meaning and application of the research work.The paper then goes further to interpret how the statistical technology works by giving out the definition and computation method of the according statistical tolerance parameters. It sets up the entire quality system that can assess the product quality and satisfy different quality requirements through the Cp-k plane that combines various quality targets. By doing so, the decision and control of the product quality becomes more convenient, accurately and direct.After the research on the statistical tolerance technology for the part level, the fit and assemble level is then researched. And in this section, the conception, meaning and computing method of the direct process capacity index and complete process capacity index are put forward. These together with the setup of the model of the assess parameters of the fit quality and with the computation with the known statistical parameters lie the theoretical ground for the control of the target of the fit quality.To make the theory more applicable, the process that is abnormal distributed is also researched through the Monte Carlo method. The main research includes:the research of theβdistribution, the model software develop of theβdistribution parameter fitting, the quality optimization control in the real environment and the according optimization algorithm.The application of the theory above is also shown in this paper. The remote manufacturing system and all the methods, technology such as the information exchange technology and the multi-intelligent process quality control are all discussed. The intelligent integrated quality control technology based on the SPC and EPC method is especially further researched.The supporting C++ library function for the probability, the inference of the statistical process and the statistical tolerance is developed to form the integrated quality control system for the manufacturing process based on the statistical tolerance. Finally, three examples are given to illustrate the research in this paper.