A study on fatigue and dynamic performance of induction-hardened sintered powder metal gears. (Case of module 2, standard pressure angle 14.5.DEG. and contact ratio 2.172).

Abstract

A conventional skew gear pair does not change its relative position of gear axes. On the contrary, one of the axes of the gear pair offered in this paper is able to be displaced one-parametrically on the space fixed to the other gear axis. At any relative position of the gear axes, the gears rotate at a constant speed ratio. The displaceable axis gear pair has three backgrounds as follows. (i) The gear pair is potentially a power transmission element. (ii) The motion of these gears can be applied to the generating motion of gear manufacturing. (iii) The gear tooth bearing problem is based on a deflection or displacement of the gear axis in loading. This paper discusses the relative curvature of gear tooth surfaces and the motion of the tooth bearing pattern.2145Three kinds of induction-hardened sintered powder metal gears were fatigue-tested using a power circulating gear testing machine in order to elucidate the fatigue strength and failure mode. The relation between the tooth profile change and the dynamic performance in the fatigue tests of the gears were also investigated. The fatigue strengths of three kinds of gears were almost the same. The failure modes in these gears were tooth breakage at the tooth fillet, tooth breakage due to pitting near the pitch point, and destructive tooth surface failure. Except for one case of the destructive tooth surface failure, the dynamic performace changed slightly during the fatigue test since the tooth profile deterioration was small. The occurrence of the destructive tooth surface failure influenced the dynamic performance of the gear.