| Summary: | 碩士 === 明新科技大學 === 精密機電工程研究所 === 97 === The worm gear set is one of the cross axes transmission mechanisms. Worm gear set can conquer the tooth undercutting problem, which occurs due to the small number of teeth of conventional gear sets with some special modules. Therefore, worm gear set can provide high gear ratios that spur and helical gear set could not offer. Besides, the worm gear set has a larger contact ratio which enables its loading capability.
In this research, mathematical model of a worm gear set is developed based on the theory of gearing and the technique of computer aided design. The worm is generated by an asymmetrical grinding wheel. The mathematical model of the asymmetric ZK-type worm surfaces can be obtained by simulation of the generation mechanism of the grinding wheel and worm. With the design of an oversize worm type hob cutter, the mathematical model of the worm gear surfaces can be obtained according to the oversize hob cutter and worm gear hobbing mechanism. The equation of meshing between the oversize hob cutter and the produced worm gear surfaces is also studied. Based on the developed mathematical models of the worm and worm gear, the finite element stress analysis of the worm gear set is performed. Analysis results of the asymmetric ZK-type worm gear set are compared with those of conventional symmetric ZK-type worm gear set. The analysis results are most helpful to the designer and manufacturer of the worm gear set.
Key words：Worm and worm gear set, ZK-type, Oversize hob cutter, Asymmetric tooth profile, Stress analysis.
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