Injection molding machine for two-material molding and method of controlling the same

An injection molding machine for two-material molding comprising:

• a reversal pedestal that is provided between a movable die plate to which a movable side mold is attached and a fixed die plate to which a fixed side mold is attached and movably in a same direction as the movable die plate;
• a rotational die plate that is 180 degrees rotatable on the reversal pedestal and to which molds are attached on both sides thereof to fit with the movable side mold and the fixed side mold and define respective cavities;
• a movable die plate mold opening and closing unit that opens and closes the mold of the movable die plate;
• a rotational die plate mold opening and closing unit that opens and closes the molds of the rotational die plate;
• a mold clamping unit that mold-clamps the three sets of die plates simultaneously after mold closing;
• and
• two sets of injection units that plasticize different resin materials and injection-fill the materials, wherein
• the mold clamping unit is a hydraulic mold clamping unit that mold-clamps the three sets of die plates simultaneously,
• the movable die plate opening and closing unit is a movable die plate opening and closing unit driven by an electric motor,
• the rotational die plate opening and closing unit is a rotational die plate opening and closing unit driven by an electric motor,
• a rotating unit for the rotational die plate is a rotation driving unit driven by an electric motor attached to the reversal pedestal, and
• a positioning pin is provided to the reversal pedestal and on which the rotational die plate rotating on the reversal pedestal abuts at rotational limits thereof, the positioning pin being made to protrude so that the rotational die plate is placed face to face with an opposite die plate at a position where the rotational die plate reaches one rotational limit and at a position of another rotational limit in a returning direction thereof.