GB191229380A - Improvements in Gear-cutting Machines. - Google Patents

Abstract

29,380. Parsons, Sir C. A., Carnegie, A. Q., and Cook, S. S. Dec. 20. [Cognate Application, 1062/13.] Gear-cutting.-The irregularities formed in the work in gear-cutting are distributed in spirals making a comparatively small angle with the plane of revolution of the work, thus destroying periodic correspondence of such irregularities with the irregularities of the master gear employed. In one arrangement, as described with reference to hobbing helical wheels, the master worm-wheel 4, Fig. 4, is connected to the table through crown teeth 27 driving a countershaft 17 mounted in bearings on the table and driving a second shaft on the table having a worm-wheel meshing with a worm 12 on a fixed or reversely-rotated central spindle. In the arrangement shown in Fig. 1, two tables are employed, one carrying the work and the other the wheel 4, relatively rotable as controlled by a similar train of gearing. In order to avoid disturbing the ratio of the change gear c calculated in the ordinary way, the added rotation given to the work is compensated by the gearing 25. In a further modification, the two tables are connected by a train of spur gearing, or by other arrangements of differential gearing. More than two tables may be employed in the above manner. The object of the invention may be attained by rotating the portion of the machine carrying the cutter through an arc around the work axis during the cutting, or by arranging the driving worm and its gearing in such a manner that the worm may move around an arc of the worm-wheel.