A hybrid design support system for a die casting scheme (a temporary binding for examination purpose)

This thesis employs the knowledge and feature-based approach, fuzzy judgment technique and computer-aided method to present a hybrid design support system (HDSS) for a die casting scheme. The design of the die casting scheme includes parting scheme determination, gating configuration and process parameter definition.; A parting scheme is mainly influenced by the geometry of a die casting. Geometrical feature analysis involves detection of concave features and determination of their release directions. A ray detection method is proposed for recognizing and extracting concave features from a die casting. The minimal release direction principle and vector plane approach are proposed to solve for the release direction of the concave regions.; In the stage of parting scheme generation, the direction-shifting approach is used to generate the parting schemes. Each possible parting direction will match one or more planes as possible parting schemes based on heuristic knowledge or design rules. All possible parting schemes can be generated by shifting all of the possible parting directions.; The performance of a parting scheme is identified by multiple design rules. In order to evaluate the parting schemes, a series of evaluation models is developed by formulating design rules as satisfaction or test functions. Then the parting scheme is evaluated by the function values, each of which reflects an aspect of the performance of a parting scheme. Thus a quantitative measurement on parting scheme performance can be realized.; A fuzzy synthetic evaluation technique is proposed for the selection of process parameters. By fuzzy transform, the contribution of each discrete level and each factor can be synthetically considered. The fuzzy synthetic evaluation can give reasonable and consistent result.; In development of gating design system, a knowledge-based technique is applied. The case-based approach and feature-based CAD approach are combined to generate a gating configuration. The case-based approach is used to match the successful cases of gating configuration by case reasoning. The feature-based CAD approach is used to design a gating system under an interactive CAD environment based on casting feature and gating knowledge.