Automatic Feature Recognition of Cross Holes in Hollow Cylinders

Automatic Feature Recognition (AFR) techniques provide the capabilities for translating the data of the part definition between Computer Aided Design (CAD) system and the feature needed to be determined; these techniques take a general CAD model, which is commercially available for providing an automated interface to extract and recognize the manufacturing features from the CAD model. Standard for Exchange of Product (STEP) format is an international standard for transporting geometric and non-geometric data between CAD and Computer Aided Manufacturing systems. Many researches have investigated the AFR in symmetrical features in rotational parts, but few studies have tried to recognize the cross-hole feature because of the recognition difficulty of such feature. A cross hole is recognized with existence of (B-spline Curve with Knots) string in (STEP AP203) neutral file. Cross holes might be perpendicular, offset or inclined to cylinder's axis, it also can be blind or through. Extraction of the necessary information from (STEP) file for generating the parameters of the manufacturing operation becomes a significant task. In this paper, a new approach for automatic recognition of cross hole feature in hollow cylinders is developed, This approach has been built by connecting the Visual Basic programming language (VB) to the SolidWorks software. The drawing is sent to the VB after saving it as a (STEP AP203) file. VB extracts and recognizes the cross-hole feature according to the rule-based reasoning, some case studies for demonstrating the application of this method on different cases of the cross-hole are presented.