To reduce the deformation caused by internal stress by providing an engaging recessed or projected part to the exterior angle surface of a disk shape.
Annular engaging recessed parts 2 having a U-shaped cross section are provided to both upper and rear side surfaces of the rim 1 of a gear one by one, and annular projected parts having a U-shaped cross section are provided to the inner surface of the cavity of a mold corresponding to the recessed parts 2. After the mold is filled with a resin, cooling gas is introduced from a gas introducing passage under pressure to induce a sink in the inner peripheral surface of the rim 1. The rim 1 shrinks as the advance of cooling to be ready to deform but, since the peripheries of the engaging recessed parts 2 are rapidly cured to be mechanically engaged with the annular projected parts of the inner surface cavity, the deformation of the rim is prevented by this engaging force. This engaged unevenness is set to a position and direction capable of effectively preventing the deformation of a molded article by the mechanical engaging force, but this position and direction are appropriately selected in consideration of the shape and structure of the molded article.
HATAKEYAMA TOSHIHARU
SENOO SHINYA
WATABE JUN
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