Machining method of large-sized cylindrical worm gears with Niemann profiles using CNC machining center

Abstract

In this paper, a machining method of large-sized cylindrical worm gears with Niemann profiles using a computer numerical control (CNC) machining center is proposed. For this study, the tooth contact pattern and transmission errors of large-sized worm gear pair with Niemann profiles are analyzed before machining of the worm and worm wheel. Next, the machining conditions of worm are determined calculating each offset distance between the worm axis and the center axis of the end mill, and then the worm is machined by swarf cutting that means machining by the side surface of the end mill. The tooth profiles of worm wheel are modeled using a 3D computer-aided design (3D-CAD) system based on the analyzed results and the worm wheel is machined by swarf cutting through a computer-aided manufacturing (CAM) process. Afterwards, the axial tooth profile of the machined worm, and the tooth surface deviations and surface roughness of the machined worm wheel are measured. Moreover, the experimental tooth contact pattern is compared with analyzed one. As a result, the validity of the proposed machining method of the large-sized worm gears with Niemann profiles using a CNC machining center was confirmed.