Computer-aided fixture design system for comprehensive modular fixtures

Fixture design plays an important role at the planning stage before shop-floor production. A desired fixture design can be employed to hold the workpart securely so that slippage and excessive deformation can be prevented during machining. Therefore, appropriate fixturing contributes highly to machining quality. To reduce lead time and the human effort devoted to fixture planning, computer-aided fixture design (CAFD) is required. In this paper, a CAFD system consisting of three modules, i.e. Fixture Data Management, Fixture Element Selection and Fixture Layout Design, is developed. According to fixture feature recognition and classification, a comprehensive fixture database in the Fixture Data Management module is constructed to maintain efficiently the fixture-related data. The domain of the fixture database consists of modular mechanical fixtures, modular hydraulic fixtures and modular V-blocks. After expertise extraction, suitable fixture elements can be automatically selected according to the machining conditions in the Fixture Element Selection module. Finally, by integrating previous reasoning algorithms, fixturing locations and orientations are determined. Feasible fixture layouts that meet manufacturing and inspection specifications can be generated in the Fixture Layout Design module. The prototype system is implemented under commercial CAD and database management system (DBMS) software. Comprehensive fixture databases and a rule-based knowledge base are built to provide effective data management. The paper aims to propose a systematic CAFD framework and application system to provide efficient decision support for different types of fixture planning.