Mold clamping apparatus provided with forceful mold opening mechanism

A mold clamping apparatus provided with a strong-force mold opening mechanism, the apparatus comprising:

• a base:
• a stationary platen supporting a stationary mold and fastened to the base;
• a mold clamping mechanism disposed parallel to the stationary platen and supported by the base so as to be freely movable in an axial direction along a guideway, the mold clamping mechanism having an outer peripheral side surface extending around a periphery thereof;
• a movable platen supporting a moveable mold and disposed between the mold clamping mechanism and the stationary platen and freely movable along the guideway relative to the mold clamping mechanism, the movable platen having an outer peripheral side surface extending around a periphery thereof and being spaced apart from the mold clamping mechanism in the axial direction;
• one or more tie bars extending from the stationary platen completely through the movable platen and through the mold clamping mechanism;
• wherein the one or more tie bars each have a series of circumferential grooves, and the mold clamping mechanism has one or more half nuts movable into and out of meshing engagement with the series of circumferential groove on respective tie bars to close and open the half nuts;
• a mold opening and closing mechanism connected to move the movable platen along the one or more tie bars and the guideway;
• at least one strong-force mold opening mechanism that opens the molds only at an initial stage of mold opening, that extends across the space between the movable platen and the mold clamping mechanism, and that moves the mold clamping mechanism in the axial direction relative to the one or more tie bars to synchronize the position of each half nut with the circumferential grooves on respective tie bars, each strong-force mold opening mechanism being configured to exert a greater axial force than that exerted by the mold opening and closing mechanism, each strong-force mold opening mechanism comprising an electric motor for rotationally driving a ball screw, and a brake for braking the electric motor, attached to the outer peripheral side surface of one of the mold clamping mechanism or the movable platen, and a nut threadedly engaged with the ball screw and attached to the outer peripheral side surface of the other of the mold clamping mechanism or the movable platen;
• and
• a control unit configured to control the mold opening and closing mechanism, control the mold clamping mechanism, control opening and closing movement of each half nut, control each strong-force mold opening mechanism, and control a position of each half nut so that the half nut is synchronized with the circumferential grooves on its respective tie bar by the strong-force mold opening mechanism.