Flexible tools for specifying design variation

Abstract

This paper describes flexible tools for specifying design variations that are based on non-uniform profile tolerance definitions. These tools specify bounds of design performance that can be used for negotiation among engineers in a collaborative design process. These specification methods allow for the capture of many different design functions that are not easily described with current tool designs. In addition, these specification methods lend themselves to efficient verification methods. Profile tolerance definitions provide the most general variation controls for complex mechanical surfaces. Common design practices and engineering standards for profile tolerances exhibit many weaknesses and limitations. We present a rationale for a complete specification approach using B-splines [1, 2] for profile tolerances, and illustrate the approach with examples. B-splines can be used to specify both uniform and non-uniform profile tolerance boundaries. Subsequently, algorithms for the evaluation of actual feature deviations and reporting methodologies for such tolerance zones are presented.