A Gear Hobbing Attachment for Manual Milling Machines to Facilitate the Production of Exotic Gears for Full-Scale Working Prototypes

Abstract

This thesis aims to present the design, development, and fabrication of a gear hobbing attachment tailored for manual milling machines. The primary objective is to create a versatile, cost-effective tool that streamlines production of standard and exotic gears, with a specific focus on gears needed to create full-scale working prototypes, to test the performance of the gear train and to ready prototypes for pre-manufacture analysis. This approach seeks to replace the industry-standard prototyping method of manual indexing, which is time-consuming and error-prone, with a more efficient, reliable approach that mirrors the gear hobbing process used for industrial production.

The distinctive advantages of this gear hobbing attachment would be especially relevant for creating worm, helical, and screw gears. Because of their complex geometries, these gear types are effectively impossible to produce through conventional manual methods. Currently, producing such gears requires dedicated gear cutting machines and skilled operators, which drastically raises the cost of producing such gears for a prototype.

For startup designers and labs, while using a CNC machine with a 4th axis is a feasible option for creating certain gear components, this approach can be time-consuming and challenging to set up. It requires special CAM software packages and programming skills, along with the use of very small cutters, making it primarily viable for gears with larger modules, typically 1.5 and above. [9]

The proposed gear hobbing attachment would make the creation of production-accurate prototypes simpler, less costly and more accessible. This innovation would also make it practical to create gear aspect ratios typically unavailable in standard gear catalogs, such as large ring gears or thin worm wheels, providing greater design freedom and flexibility in prototype development.

The proposed gear hobbing attachment will consist of a spindle mounted to the bed of the manual milling machine with an AC servo motor for drive.