INJECTION MOLDING DEVICE

PROBLEM TO BE SOLVED: To easily perform the release of the fixation between each set of plungers and a chamber by resin with a simple structure by a method wherein the driving force of each plunger is made to be switchable so as to allow to drive the plunger by a limiting driving force, which exceeds beyond the driving force of the plunger at steady action. SOLUTION: The fixation by a resin is detected with an overload detecting sensor through the going-up of a plunger rod 5 under the condition that a torque limiting value acting to going-down side, which is a little higher than the starting torque of a motor 30, is set to a servo amplifier 32 during the downward motion of the plunger rod 5. Further, in the release mode A, in which the fixation by a resin is released within the limit of the plunger torque, the fixation of resin is released by lowering the plunger rod under the condition that the plunger torque is set to be the torque Tc lying between the plunger torque TA, at which the part of a plunger part breaks, and the starting torque TB at the lowering of the plunger. Furthermore, in the release mode B, in which the fixation by the resin is released under the condition that the limitation on the plunger torque is struck down, the fixation by the resin is forcibly released by lowering the plunger rod 5 with its maximum torque under the condition that the torque limit of the motor 30 is struck down.