Patent ID: 8715548

Claim:
A mold fastening device comprising: a fixed die plate to which a fixed metal mold is secured; a rear plate coupled to the fixed die plate by tie bars; a movable die plate to which a movable metal mold is secured, which is movably provided between the rear plate and fixed die plate; a toggle mechanism comprising a cross-head, the toggle mechanism provided between the rear plate and movable die plate and configured to move the movable die plate back and forth among a plurality of positions and to lock the fixed metal mold and movable metal mold; and a drive motor coupled to the cross-head of the toggle mechanism, configured to drive the cross-head, and configured to, at each position of the moveable die plate, be controlled to have a rate of increase or decrease of rotational speed corresponding to the position of the moveable die plate, the rate corresponding to each position being determined by multiplying a rate of increase or decrease of rotational speed at each position of the moveable die plate for a desired torque by a reciprocal of a ratio of a speed of the moveable die plate to a speed of the cross-head; wherein: a stopping position where the cross-head should be stopped is associated with at least one of the rate at which to accelerate the cross-head from the stopping position and that at which to decelerate the cross-head to the stopping position, and the cross-head is operated at an acceleration or deceleration that corresponds to the stopping position, thereby driving the drive motor at a constant output torque, regardless of the position of the movable die plate, while the lovable die plate is being accelerated or decelerated.