| 摘要 |
PURPOSE:To locally thin a product and consequently embody the weight-saving of the product by a method wherein a comparatively thin walled part is formed by gradually changing the wall thickness from a film gate side along the width direction of a product and the gradually changingly forming part at the edge of a film gate is brought near to the film gate. CONSTITUTION:The injection mold consists of a fixed mold 3 and a movable mold 4 so as to form a cavity 5 at the mating mold surfaces of both the molds. The cavity 5 is a long thin plate-like space conforming with the shape of a bumper. On one edge side of the cavity 5, a film gate 6, which has thin band-like shape running longitudinally, is formed. The thickness of the cavity 5 for molding the bumper at the site, in which the film gate 6 is provided, consists of a thicker wall forming part 5A, in which the thickness starting from the film gate 6 side and running along the axial direction of the bumper is comparatively thicker, a gradually changingly forming part 5B, in which the thickness changes gradually, and a thinner wall forming part 5C, in which the thickness is thinner. The gradually changingly forming part 5B in the neighborhood of the edge of the film gate 1 is brought close to the film gate 6 so as to realize the smooth filling into the edge of the cavity 5. |
