Research On Variability Control Of Mechanical Product And Its Key Technologies

Because of the development of society, people's ideology has been changed. Advocating individuality is the notable character in this era. As a result, the environment enterprise locating in has been changed also, in which the product variety is the most essential requirement, and product delivery deadline and product cost are both chief competition factors. However, providing abundant variety in production will lead to cost increasing, missing product delivery deadline and so on. Therefore, the key measure of solving this contradiction would be to implement mass customization.Variability is a kind of ability of producing variety product to satisfy with market requirement. The variability of mechanical product can be divided into external product variability and internal product variability. Controlling internal product variability can provide external product variability while control product cost and its deadline of delivery effectively. However, modeling variability is an effective measure to control variability. This paper, by analyzing internal product variability in the product lifecycle, researches emphatically the methods, work logic and key technologies of variability and its control in product development, design, manufacturing process of mass customization. The key study contents are described as follows:Firstly, based on the definition of product lifecycle and the analysis of internal product variability in different lifecycle phases, two kinds of internal product variability control was identified by summarizing the variability characteristics in product development, design and manufacturing phases, namely product structure variability control and manufacturing process variability control. At the same time, variability control layers of product structure and manufacturing process were studied respectively. Then, component cell was proposed. Based on it, product family model for mass customization variability and its modeling were researched in detail.Secondly, in order to evaluate the variability of product family, process platform programming based on component cell was proposed and general product and process structure of product family used to parameter statistic and analysis was constructed as well. Then, the variability index of product family was established with the elements of type, usage amount, reuse times and product output, including part variability control index and manufacturing process variability control index.Thirdly, aiming to the issue of product structure variability control, the customization process combining variant design of product basic framework and configuration design based on product basic framework was put forward. For product basic framework variant, part information model was proposed. At the same time, mating relationship between constitutes component of product and assembly mating graph were defined as well. For the configuration design based on product basic framework, the configuration module and constraint relationship model between configuration modules were studied, and configuration design process based on product basic framework was researched as well. Fourthly, in order to establish the dimension constraint model identified by assembly mating graph, it is necessary to decompose assembly mating graph into different sub-constraint group. Therefore, dimension constraint formula of each sub-constraint group was established, In addition, the product parameter we got is always incomplete according to customer requirements and/or AACG sub-constraint group during product customization, In order to implement variant design effectively, maximum likelihood estimation method for incomplete data was proposed, and EM algorithm was adopted to simplify its operation process. So the approximative value of unknown design parameters can be worked out conveniently. It would provide support for variant design.Fifthly, aiming to the issue of manufacturing process variability control, product customization mode and corresponding manufacturing strategy are discussed and control technologies for manufacturing process variability were researched as well. Then, at product layer, the characteristic of manufacturing process changing along with product structure's changing was realized based on process platform. At part layer, variant design and NC programming were studied in detail, including NC programming for variant design, machining feature definition, designing NC subprogram base, master NC program, and production knowledge base. Then, the key technologies of NC program variant based on master NC program were discussed deeply.Finally, in terms of the above-mentioned philosophy and methods, a prototype system supporting mechanical product variability control was analyzed and designed. The key modules of it were developed and integrated based on Solid Edge 15 and VB 6.0. In the end, using a Textile Machine Co., LTD. as a case, the application and its results of each subsystem were presented. It indicated that variability analysis method, product family model for mass customization variability, index of product family variability, assembly mating graph, maximum likelihood estimation method, EM algorithm, master NC program and so on are viable and can be implemented well.In one word, variability analysis and its control of mechanical product, product family model for mass customization variability design, and key technologies to implement product structure variability control and manufacturing process variability control in this thesis establish a foundation for solving the contradiction between product variety and product cost and product delivery deadline.