高強度球状黒鉛鋳鉄歯車の歯切り加工に関する基礎研究 : 第3報, ホブ切り条件について

This paper discusses the hobbing of gears made of austempered spheroidal graphite cast iron, which has recently attracted attention as a new material for gears. This iron has many advantages, such as the properties of casting parts of complicated forms easily and a high strength equivalent to that of steel, and is also an economical material. However, this cast iron is hobbed before austempering heat treatment at present, because the hobbing of the teeth of a hardened gear blank is considered to be very difficult. Yet, if the cutting of a hardened gear blank is possible, the cost will be lower because the gear can be used without performing a finishing operation on the tooth surface to remove the distortion caused by heat treatment. The following conclusions are obtained. (1) The life of the hob appears to be largely affected by the feed of the hob, and the life is longer at small feed. The influence of cutting speed is also large, as in the case of hobbed alloy steel. (2) It is observed that the teeth with greatest wear are concentrated in one area of the hob. (3) The accuracy of hobbed ADI is very good.