Patent ID: 6386853
Filing Date: 2002-05-14
Classification: B29C

Abstract:
A motor-driven injection driving apparatus for an injection molding machine, which is configured so that the rotation of an electric motor is converted into linear motion, and an injection screw is moved forward and rearward by said linear motion, comprising:a fixed frame provided with an injection cylinder in which said injection screw is fitted so as to be moved forward and rearward; a movable frame which is provided so as to be moved forward and rearward in the axial direction of the injection cylinder and which is moved to said fixed frame side together with said screw upon the injection process; first and second injection drive motors installed on said fixed frame; first and second ball screw shafts pivotally supported on both sides of said fixed frame so as to be in parallel and symmetrical with respect to the axis of said injection cylinder and so as to be rotatable, said first and second ball screw shafts extending from said fixed frame to said movable frame; first and second power transmission mechanisms for transmitting the rotational forces of said first and second injection driving motors to said first and second ball screw shafts, respectively, while reducing the speed; first and second ball screw nuts, which are provided on both sides of said movable frame and threaded on ball threads of said first and second ball screw shafts, respectively; a screw drive motor, which is mounted on said movable frame, for rotatively driving said injection screw; and a controller for synchronously rotating said first and second injection drive motors, said movable frame being moved by rotation of said first and second ball screw.