| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize an internal tooth member and improve quality, durability and productivity of the internal tooth member. SOLUTION: This internal tooth member has a first cylindrical part and a second cylindrical part larger in diameter than this first cylindrical part. Additionally, first and second internal teeth are respectively formed by projecting them inward in the diametrical direction on inner peripheral surfaces of the first and second cylindrical parts. As it is possible to form an engaging part by projectively forming the second internal tooth on the inner peripheral surface of the second cylindrical part, a diameter of the internal tooth member does not become large. Since a part between the second internal tooth and a recessed part 72 is not thinned in accordance with formation of the second internal tooth, it is possible to prevent growth of a crack and to improve durability of the internal tooth member. Also since no sagging is caused on an inner peripheral surface of the engaging part, it is possible to improve quality of the internal tooth member.
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