| 摘要 |
PURPOSE: To provide a resin molded article with a fine dimensional accuracy, being light in weight, and having high strength. CONSTITUTION: This resin molded article having an annular part 2 such as a toothed wheel has a hollow part 6 formed within the annular part. The hollow part is formed within the annular part by pushing a part of the molten resin out of the cavity through the pressure of a hollow part forming fluid that is pressed in the molten resin within the cavity of the mold. On the end surface of the annular part, a pressing in part 8 of the hollow part forming fluid and an extruding part 9 of the molten resin are formed apart away from the diameter direction of the annular part, and the hollow part is divided in two directions from the pressing in part of the hollow part forming fluid within the annular part and extends in a semicircular shape to the extruding part of the molten resin or in the vicinity thereof respectively. Thus, the annular part can be a hollow structure with a thin wall thickness almost over the entire circumference. |
