Ontology-based method for automatic generation of fit tolerances

Fit tolerance is an important index for assessing the fit quality of mechanical products, and the key elements of fit tolerance-base fit system and basic deviation are manually specified by designers. For the same mechanical product design, different designers may specify different fit tolerances. First, an extended fit tolerance representation model is constructed by introducing a fit property layer. The constructed model is hierarchically organized and consists of a part layer, a fit nature layer, a datum layer and a fit type layer. The knowledge of these four layers is defined through Web Ontology Language 2 (OWL2) assertions. Secondly, a meta-ontology model for fit tolerance representation is constructed and with this meta-ontology model, a model for fit tolerance representation in computer-aided domains can be derived through its unary and binary relational terms. Based on this, the fit tolerance representation model is formalized using OWL2, and the constraint relationships between the model hierarchies are represented in Semantic Web Rule Language (SWRL) and the appropriate baseline fit system is derived by reasoning using Drools Rule Engine. Finally, the working process of the method is demonstrated through an engineering example to verify the effectiveness of the method.