On the New Feedback Controlled Precision Gear-Hobbing Machine

Abstract

Based on the preliminary research of one of the authors, a new and practical feed-back controlled gear hobbing machine for fine pitch gears was built at a low cost. The average and minimum of the maximum angular position errors so far obtained with the gears hobbed by this machine is 20 sec and 11 sec, respectively, when the module is 1 and the pitch circle diameter is 72 mm. Such accuracy is obtained by virtue of the special design of the machine, which makes use of an electro-hydraulic servomechanism to correct the error of the driving worm wheel. The servomechanism is actuated by the relative displacement of the driving worm wheel and the master worm wheel as well as the signal from the cam shaped to eliminate the inherent error of the master worm wheel. This paper presents the basic analysis, the design of the machine and the experimental result.