| 摘要 |
A clamping mechanism, effective to press a movable platen against a fixed platen in a terminal phase of a mold-closing stroke of an injection-molding machine, comprises a series of coaxial annular pistons received with progressively larger clearances in respective inner peripheral grooves of a stationary housing linked by tie rods with the fixed platen. The pistons, which can be interconnected by elastic bolts, bear upon a mounting frame, slidable along the tie rods, supporting a pair of laterally withdrawable shutters which in their retracted position give passage to a tubular thrust member coaxially surrounding a plunger secured to that thrust member and to the movable platen. The opposite end of the plunger carries a piston head received, within the housing, in a central driving cylinder to which hydraulic fluid can be admitted from either end for advancing or retracting the movable platen in a mold-closing or a mold-opening stroke. In a forward position of the movable platen, the tubular thrust member just clears the shutters which are then moved toward each other into a working position behind that member whereupon fluid is admitted to the housing grooves for pressurizing the cascaded annular pistons to clamp the mold shut. Normally, the cascaded pistons move as a unit into and out of their clamping position; if, however, the absence of a mold or an incorrect positioning of the shutters results in overtravel, these pistons separate against the elastic force of their connecting bolts, if any, as they come at staggered intervals to rest against the end walls of their respective grooves, thereby dividing the reaction force between the housing and the several pistons.
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