| 摘要 |
A cooling fan has a ring-shaped metal spacer, a boss of substantially a cylindrical shape made of a synthetic resin that is molded integrally with the spacer as an insert and lural blades that extend outwardly from the boss. A deep-drawn part is provided on an outer circumferential part of the spacer at an inside of the boss. A thickness of the boss is made large at around a front end side of the blade on which the largest stress is applied. A rib at an inner periphery of the boss at around the front end side of the blade is made thicker than the other ribs. Moreover, an interval between that rib and an adjacent rib is made narrower.
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