Research On Mechanical Product Design Process Based On Function Flow

The product design process is the primary phase and the creative and challenging part in product lifecycle. The implementation effect of the follow-up manufacture process is directly influenced by design results that are also the major factor of controlling product cost. Along with increasing of product complexity, urging of market requirement and spreading of networked product development mode, product design theories and methods have attracted wide attention from academies and industries and become important research directions and application fields. In this dissertation, an idea for product design process based on function flow is put forward. Under computer supported network environment, the theory and methods of integration of product design process, which involves from the initial acquisition of customer requirements to the final guarantee of assembly function, are studied.The pervious research works on the product design process are summarized, and the deficiencies are analysed. The concept of function flow is proposed in the product design process according to the characters of the product design process. The product design process based on function flow is constructed in which the contents of conceptual design and detail design are included. The conceptual design phase and detail design phase are united through the function flow that means concurrent changes of functions in their forms and contents during the design process. The united design process is of importance to support design problem solving for meeting the product requirement functions.The concept of problem domain between different knowledge spaces in the design process is presented. The definition and classification of requirements and requirement functions are ascertained, and their essential relation is analysed. A method based on fuzzy set expression and entropy calculation is put forward in order to acquire effective customer requirements from customer's complicated requirement information. The abstraction principles and classification method of the customer requirement functions are established, and the corresponding matrix expression is given. By this way, the customer requirement functions, which reflect the essence of customer requirement, can be acquired.A method of space union transformation based on function matrix is brought forward in order to transform the customer requirement functions into designer requirement functions. The function-structure model of conceptual design phase is built. The product's principle structure modelling of conceptual design phase can be achieved by the IDEF0 method after the function carriers, such as principle components, function connectors, function surfaces and working principles, corresponding with different function level, have been gotten. An optimization method based on graph expression and energy flow control is built to determine whether the product's principle structure model has redundant parts or not, in order to optimize the structure and confirm its rationality.Product assembly evaluation hierarchy and assembly analysis scheme are presented for manual assembly and automatic assembly. The products design criteria are set down. The assembly cost model and quantitative efficiency evaluation have been proposed to make qualitative or quantitative analysis in order to evaluate the assemblability of product, and put forward the corresponding suggestions of the redesign or correction to ensure the assembly function of products.The general architecture of a prototype system for function-flow-based product design process under the network environment has been given to validate the ideas and methods proposed in this dissertation. By using Java, VRML, Delphi, SQL Server and Socket, four sub-modules including Customer Requirement Function Acquisition (CRFA), Designer Requirement Function Acquisition-solution-optimization (DRFA), Web-based Design for Assembly function (WebDFA) and a networked platform are developed and implemented. A practical case is used to validate the correctness...