Patent ID: 7993129

Claim:
An injection molding machine comprising a moveable platen, a fixed platen, at least two tie bars arranged between the moveable platen and the fixed platen to have the moveable platen move thereon and an open-close mechanism of lock nut provided on the periphery of one end of the moveable platen to engage with the respective tie bar, wherein the open-close mechanism of lock nut comprises two pairs of lock nuts, at least one clamping unit and a pair of rods for connecting the pairs of lock nuts; the two pairs of lock nuts are provided at the same horizontal plane or the same vertical plane; a first nut of a first pair of lock nuts is connected to a first nut of a second pair of lock nuts by a first rod, a second nut of the first pair of lock nuts is connected to a second nut of the second pair of lock nuts by a second rod, wherein: the clamping unit further comprises an execution element and a pair of connecting bars for open-close action symmetrically arranged; a first end of a first connecting bar for open-close action is connected to the second nut of the first pair of lock nuts, and a first end of a second connecting bar for open-close action is connected to the first nut of the second pair of lock nuts; a second end of the first connecting bar for open-close action is connected to a second end of the second connecting bar for open-close action, and the second end of the first connecting bar for open-close action and the second end of the second connecting bar for open-close action are driven by the execution element simultaneously to open or close the first pair of lock nuts and the second pair of lock nuts simultaneously, wherein: the execution element comprises a hydraulic cylinder, a crosshead and a plurality of guide bars in parallel; the plurality of guide bars are fixed on the moveable platen; the hydraulic cylinder is fixed on the moveable platen by the plurality of guide bars; a piston rod of the hydraulic cylinder is vertically fixed at the center of the crosshead; the crosshead is movable along the axis of the plurality of guide bars; the first connecting bar for open-close action comprises a first arm and a second arm, a first end of the first arm is fixed to the second nut of the first pair of lock nuts, and a first end of the second arm of the first connecting bar is hinged to a first connecting end of the crosshead, a second end of the first arm of the first connecting bar is hinged to a second end of the second arm of the first connecting bar; and the second connecting bar for open-close action comprises a first arm and a second arm, a first end of the first arm of the second connecting bar is fixed to the first nut of the second pair of lock nuts, a first end of the second arm of the second connecting bar is hinged to a second connecting end of the crosshead, a second end of the first arm of the second connecting bar is hinged to a second end of the second arm of the second connecting bar.