Spindle drive exerting closure force in injection molding machine, includes electric motor for relative rotation of spindle and nut, with transmission unit acting on spindle

摘要

The mold platens form an axial abutment for the spindle (3) or spindle nut (4). An electric motor causes relative rotation between them (3, 4). A transmission unit (8-14) introduces closure force into the spindle through interlocking- or frictional coupling. An electric motor operates the transmission. The spindle nut is coupled to the spindle in a low-friction arrangement. The transmission unit (8-14) between spindle nut (4) and the axial abutment of the spindle, acts upon the latter. A common electric motor produces relative rotation between spindle and nut, in addition to operation of the transmission unit. The transmission includes a component (10) gripping (frictionally) or interlocking with the spindle. The piston (8) of the first cylinder (9) is supported against the spindle nut. A second cylinder has a piston of greater area, supported against the transmission component (10). A fluid line (11) connects the cylinders. This includes a holding valve (15) with a bypass line (16) and a load release valve opening to the first cylinder. A system fills the cylinders with fluid. This comprises a pump and non-return valve, which are connected to the fluid line between the first cylinder and the holding valve,. Cylinder and piston are annular and concentric with the spindle. The transmission component (10) forms the first cylinder (9). The mechanism is further detailed in accordance with the foregoing principles.