Designers often need to decompose a product into functioning parts during the product design stage. This decomposition is critical for product development, as it determines the geometric configuration of parts, and has direct impact on product cost. Most decompositio n decisions are based primarily upon end-user requirements instead of product manufac turability. The resulting parts can be expensive to manufacture or are sometimes impossible to make. This thesis presents a manufacturability-driven approach which can help designers decompose bent sheet metal products into manufacturable parts.
The decomposition approach presented in this thesis takes the geometric description of an initial product design, analyzes its manufacturability, and decomposes the product into manufacturable parts. The decomposition continues until all decomposed parts are manufacturable. Near-optimal solutions are generated based on some primary concerns of design for manufacture (DFM) and design for assembly (DFA). Designers can then examine the decomposition results and decide whether they meet end-user requirements. Cut ting, bending, and assembly processes are considered as the major manufacturing processes in bent sheet metal production. Key manufacturability analyses for these process es are based upon part unfoldability, tool accessibility, and product assemblability. The final results are sent to the corresponding process planning systems and a complete production plan is generated.
A prototype system, consisting of design and decomposition modules, as well as process planners for cutting, bending and assembly, has been implemented to validate the decomposition approach. The manufacturability constraints represented in the decomposition module approximate the constraints imposed by a given manufacturing facility. A range of geometric and industrial products have been tested in the system and the results are given. We show that as the approximations of these process planners are improved, the results will also improve, without any changes to the decomposition approach.
Cheng-Hua Wang, ``Manufacturability-DrivenDecomposition for Sheet Metal Products,'' Ph.D. Thesis, The Robotics Institute, Carnegie Mellon University, September, 1997.