Patent ID: 7749419

Claim:
An injection-molding method for covering a front face of a plate-shaped member with a front side molded layer by injection-molding using a first die and a second die and a rear face of the plate-shaped member with a rear side molded layer by injection-molding using the first die and a third die, the injection-molding method comprising the steps of: preparing the first die having a front side cavity face provided in opposed relation to a mating face of the second die for covering the front face of the plate-shaped member, a first gate opening at the front side cavity face and extending substantially perpendicularly to the mating face of the second die, a second gate provided in such a manner as to bypass the front side cavity face and to open at a face to be mated with the second die and having a portion extending from an opening at the face to be mated with the second die substantially perpendicularly to the face to be mated with the second die, and switching means for guiding molding material to either one of the first and second gates; preparing the second die having a receiving face for receiving the rear face of the plate-shaped member; preparing the third die having a rear side cavity face for covering the rear face of the plate-shaped member, and a substantially J-shaped connecting passage opening at the rear side cavity face and at a face to be mated with the first die so as to fluidly connect the second gate to the rear side cavity face and having a portion extending from an opening at the face to be mated with the first die substantially perpendicularly to the face to be mated with the first die; 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; injecting a molding material through the first gate into the front side cavity to mold the front side molded layer; replacing the second die with the third die and thereby forming a rear side cavity with the rear side cavity face of the third die and the rear face of the plate-shaped member; and injecting a molding material from the second gate through the connecting passage into the rear side cavity to mold the rear side molded layer.