STEP-based feature recognition from solid models having non-planar surfaces

Abstract

To enhance the interoperability of different CAD systems, 3D B-rep models should be represented in a neutral file format. Standard for exchange of product model data (STEP) is a neutral format that supports the representation of product model data from its geometrical and topological information to life cycle data. In this work, STEP-based feature recognition (FR) system is developed, which is capable of recognising the features having non-planar surfaces from solid models represented in STEP AP203 format. The considered non-planar surfaces are elementary (cylindrical, conical, spherical, toroidal) and advanced surfaces (i.e. B-spline and swept surfaces). The STEP AP203 file is accessed through Java Standard Data Access Interface (JSDAI). The recognition of considered non-uniform elementary and advanced surface features is performed by exploring the geometry and topological representation schema of the surfaces in STEP AP203 file in two phases. In the first phase, the surface and the edge-level geometrical and topological information of the considered object is extracted. In the second phase, the features with non-planar surfaces are recognised and presented as per the data needed for STEP AP224 format. Since the FR system uses STEP AP203 file as input, after recognising features, there is minimum chance of losing information from CAD model to feature representation. The developed FR system is demonstrated with a blow moulding die, which is having different non-planar elementary and advanced surfaces. The output information of the developed FR system is useful for downstream application such as automatic generation of STEP-NC programs.

Keywords:

• STEP
• feature extraction
• CAD/CAM
• geometric modelling
• JSDAI

Disclosure statement

No potential conflict of interest was reported by the authors.