| 摘要 |
PROBLEM TO BE SOLVED: To elongate gear life longer than the life of a resin gear and reduce gear sound by molding a gear body out of resin and vapor depositing a metal film on a tooth part to be engaged with another gear. SOLUTION: This spur gear 1 used for a geared motor, an electric tool, etc., has a gear body 2 having a plurality of teeth parts 2b formed in the outer circumference of a disc flat plate 2a molded of resin, and, a hard material, for example, a metal film 3 is vapor deposited on the side surface of the teeth parts 2b of the gear body 2. The spur gear 1 is provided with the hard material in a part where teeth parts 2b of the gear are brought in contact with each other so that the abrasion of the teeth parts 2b of the gear can be reduced and the life can be elongated. Gear sound generated in the part where the teeth parts 2b of the gear are brought in contact with each other is absorbed by the gear body 2 formed of resin so as to be reduced. A thin metal plate may be stuck to the side faces of the teeth parts 2b instead of vapor depositing the metal film 3 on the gear body 2. Besides the spur gear 1, this can be applied to gears such as a helical gear and a bevel gear.
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