Using Features and Their Constraints to Aid Process Planning of Sheet Metal Parts

Abstract

Process planning is a time-consuming and tedious operation that is necessary to manufacture products. In addition, process plans must be optimized to drive machines most productively. To accomplish this goal, the authors search for plans that satisfy production feasibility requirements and time constraints. Unfortunately, this search operates in an enormous search-space that is usually impossible to navigate. Therefore, the authors use features and their corresponding heuristics to guide the search. To make the search more tractable, the authors convert some features into corresponding constraints as a priori knowledge to prune the space. The applications of these features are presented in this paper. The authors also discuss the feature interaction problems in the process planning. In this paper, the authors focus on the production of bent sheet metal parts and the machine setup. The authors have designed over forty test parts with their "parallel design" system, and the features are automatically generated as the design progresses. After the design is complete, an automatic process planning system uses the features and generates new ones to aid the production of a near-minimum manufacturing cost plan. Finally, these plans are used to produce parts on an automatic bending system.