Patent ID: 7947208

Claim:
An injection-molding method for covering a plate-shaped member having a through hole extending from a front face to a rear face with a molded layer by injection-molding, the injection-molding method comprising the steps of: preparing a first die having a gate that will face the through hole and a front side cavity face that will face the front face of the plate-shaped member, a second die having a receiving face for receiving the rear face of the plate-shaped member and a pin for blocking the through hole, and a third die having a rear side cavity face that will face the rear face of the plate-shaped member; sandwiching the plate-shaped member with the first die and the second die and forming a front side cavity with the front side cavity face of the first die and the front face of the plate-shaped member; molding a front side molded layer to the front face of the plate-shaped member by injecting a molding material such as resin through the gate into the front side cavity; opening the through hole and forming a front side cavity with the rear side cavity face of the third die and the rear face of the plate-shaped member by replacing the second die with the third die; and molding a rear side molded layer to the rear face of the plate-shaped member by piercing the front side molded layer with an injection pressure injecting molding material through the gate and filling the rear side cavity with molding material by way of the through hole.