Development of a computer-aided-design system of cold forward extrusion of a spur gear

In this study, a computer-aided-design system for manufacturing a spur gear in cold forward extrusion was developed under a graphical user interface environment. The influence of gear geometry such as total tooth number, profile shift coefficient, and module on deformation mechanics was investigated by the three-dimensional finite element (FE) program CAMPform3D in terms of complete formation of the teeth and the level of forming loads. From such investigations and literature survey on existing design practices, necessary rule bases including limiting extrusion ratio at the cross-section of the root and limiting ratio between extrusion ratios of the addendum and root of a gear were established and applied for process design of extrusion of solid or hollow spur gears. The developed system can provide a feasible set of gear and pinion geometries for a given input data satisfying required product capacities such as contact ratio and bending strength. Thus, design engineer can easily select the better product design depending on individual priority of the product and reduces the lead time and cost required at the initial design stage of extrusion of spur gears at practice.