| 摘要 |
An injection molded resin gear 1 has a rim 6 having teeth 7 on its outer periphery, a hub 4 for receiving therein a shaft, and a web 6 connecting the rim 6 to the hub 4. The thickness (t1) of the bottom 15 of the rim 6 is smaller than the thickness (t2) of the web 5. On the side faces 8 and 8 of the web 5, annular circumferential ribs 10, 11 and 12 protruding concentrically with the rim 6 and hub 4 are formed. The relationship between the thickness (t1) of the bottom 15 of the rim 6, the thickness (t2) of the web 5 and the thickness (t3) of the circumferential rib 12 is t1<=t3<t2.
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