A Study on Numerically Controlled Machine Tools for Cutting Noncircular Gears and Their Control Method

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Recently, usefulness of noncircular gears has been recognized and the demand of them is rapidly increasing. However, the conventional design and manufacturing method have no capability of production of the noncircular gears as much as the demand. Therefore, the productive manufacturing system for noncircular gears has been strongly desired. In order to improve the productivity and accuracy of the noncircular gears, the investigators tried to increase the performance of NC gear manufacturing machines. In addition, since CAD / CAM system also plays very important roll for improvement of the productivity, a new CAD / CAM system for noncircular gears were developed.The summary of this research results are as follows : First, we converted a gear shaper and a hobbing machine into NC gear manufacturing machines which can precisely cut noncircular gears. Secondly, as an application for noncircular gears, an compensation mechanism for rotational error of worm gear was proposed and it was proved … More by using the CAD system developed by the investigators that the noncircultar gears for compensation can be easily designed and produced. The ptich curves of them were deduced from Fourier transform. This design method using Fourier Transform is very useful for design of non-uniform motion mechanism because the pitch curves designed by this method are assured that both pitch curves of the driver and follower always have closed form. The CAD system including this design method enables us to design the noncircular gears very effectively in comparison with the system using empirical design methods. In additon, as the other application of noncircular gears, a new steering mechanism for vehicles was proposed. From the result of analysis, it became clear that the noncircular gears for the steering mechanism are elliptical gears. Since the steering mechanism enables the vehicle to turn with a very small radius and the elliptical gears are suitable for productin, we can anticipate that this mechanism will be used for steering system of many kinds of vehicles. Less