Shunmugam M S

To automate planning activities in a computer integrated manufacturing environment, an integrated system of feature recognition and reasoning is essential. An attempt is made in the present work to develop such a system for 3D sheet metal components. Though certain part-modellers use feature-based methodology, they lack the information required for manufacturing and entire feature information is lost when converted to a neutral format such as STEP AP-203. The proposed feature recognition identifies manufacturing features in a generic manner, while feature reasoning gives the information required for manufacturing. Taking 3D model data in STEP AP-203 format as input to the feature recognition system, the central plane of the component is first generated. Further processing of faces is carried out and various features with similar manufacturing attributes are identified using a set of rules based on the topology, geometry and Boolean logic. Different types of manufacturing features such as cut, stretched, drawn and bent features as well as composite features are effectively identified irrespective of their shape. The system proposed here was tested with components taken from industry and examples available in the published literature. The proposed feature recognition system serves as input to the feature reasoning system dealt with in Part II of this work (Kannan, T.R. and Shunmugam, M.S., Processing of 3D Sheet metal components in STEP AP-203 format. Part II: feature reasoning system. Int. J. Prod. Res., 2009 (in press)).

Both feature recognition and reasoning are needed for automating manufacturing planning activities for 3D sheet metal components. The feature reasoning system proposed here generates manufacturing information (e.g. flat pattern, locations of various features, internal cuts and blank profiles, type of tools required, operation sequence, bending sequence, etc.) for the features recognized in Part I of this paper. The issues related to flat pattern developments as experienced while using commercial software have been addressed in this work. A tool selection approach that uses standard tools for single and multiple blow features in punch presses is suggested. A zigzag method for operation sequencing and a virtual bend sequencing system are included. The system has been tested with various components and the results are compatible with industrial practices.