standard procedure for the hydraulic support of an electric drive

摘要

The force of an electric motor, whose rotational movement is translated into a longitudinal movement by a transmission, and the force of the piston of a hydraulic cylinder act in the longitudinal direction on an axially displaceable machine part. The force exerted by the electric motor is limited to a value at which no damage occurs to the transmission. In order to limit the force component applied by the electric motor, the desired value for the force acting on the machine part in the axial direction and the actual value of this force are used to form a control difference, which controls the sum of the force components acting on the machine part in the axial direction. The actual value of the force acting on the machine part in the axial direction and a value that takes into account the mechanical load-bearing ability of the transmission are used to form a desired value for the force acting on the piston in the axial direction. The desired value for the force acting on the piston in the axial direction and its actual value are used to form a control difference which controls one of the force components acting on the machine part in the axial direction. The control method is applied in injection molding machines with hydraulic assistance from an electric drive, in particular for the screw advance during the injection operation and/or in the holding phase.