Automatic identification of aspect vectors and geometrical validation of 2.5D parts

Abstract

A part can be viewed from infinite viewpoints, but it may look 2.5D from some specific viewpoints only. Its solid model may be arbitrarily oriented in space as per the designer's convenience in positioning it in an overall assembly. However, this orientation may not be suitable for proper and economic manufacturing. A manufacturing engineer has to reorient the part in such a way that it looks a 2.5D part, if possible. Manufacturing of 2.5D parts is economic and efficient since standard machine tools, cutters and clamping devices are used. An algorithm is presented to automatically determine the machining coordinate system that is convenient for machining. The selected coordinate system specifies the approach directions (aspect vectors) for machining the part. The underlying principle of the algorithm is the generation of machined faces on a three-axis CNC vertical milling machine with a set of flat-bottomed end-milling cutters and standard clamping devices. The part can have only planar and cylindrical faces under such machining conditions. Another algorithm is presented to validate whether or not a part falls under the 2.5D domain. Both algorithms are required since the present state of feature-recognition technology is limited to 2.5D parts. There is a need for a pre-processing system that automatically determines the aspect vectors for a 2.5D part and checks whether or not the design fed to the feature-recognition system is valid.