After graduating from Northern Illinois University in 2010 with a bachelors’ in mechanical engineering, Brendan Bijonowski has pursued a career in design. In 2011 he joined the engineering ranks of Arrow Gear Company, located in Downers Grove, IL as a design engineer. His passion for the geometry of gearing and attention to detail can clearly be seen in all of his work. Bijonowski is a member of the AGMA Bevel Gear Committee, where he works on defining geometry and improving rating methods. He is also a member of the AGMA Computer Programming Committee, where he applies his experience and knowledge as a gear engineer to an evergrowing collection of technical software.
The geometry of the bevel gear is quite complicated to describe mathematically, and much of the overall surface topology of the tooth flank is dependent on the machine settings and cutting method employed. AGMA 929-A06 — Calculation of Bevel Gear Top Land and Guidance on Cutter Edge Radius — lays out a practical approach for predicting the approximate top-land thicknesses at certain points of interest — regardless of the exact machine settings that will generate the tooth form. The points of interest that AGMA 929-A06 address consist of toe, mean, heel, and point of involute lengthwise curvature. The following method expands upon the concepts described in AGMA 929-A06 to allow the user to calculate not only the top-land thickness, but the more general case as well, i.e. — normal tooth thickness anywhere along the face and profile of the bevel gear tooth. This method does not rely on any additional machine settings; only basic geometry of the cutter, blank, and teeth are required to calculate fairly accurate tooth thicknesses. The tooth thicknesses are then transformed into a point cloud describing both the convex and concave flanks in a global, Cartesian coordinate system. These points can be utilized in any modern computer-aided design software package to assist in the generation of a 3D solid model; all pertinent tooth macrogeometry can be closely simulated using this technique. A case study will be presented evaluating the accuracy of the point cloud data compared to a physical part.