| 摘要 |
PURPOSE:To contrive to manufacture a high efficient float cheaply by injection molding a synthetic resin float in which the float body having a connecting arm integrally and consisting of highly foamed core and nonfoamed outer skin. CONSTITUTION:Nonfoaming synthetic resin 6 to be used as an outer skin is injected into the cavity narrowed by a moving core 5 to the specified volume of a float body, and then foaming synthetic resin 7 is injected into this nonfoaming resin. Next, the cavity is expanded to specified volume by shifting the moving core 5, while keeping the temperature condition suitable for foaming. Hence, the expansion ratio of the foaming synthetic resin is improved. As the inside of the float body is foamed into low specific gravity and high foaming state, the float has high effeciency, and then outside liquid does not infiltrate into the float inside, because the outside skin is made of nonfoamed resin. |
