LINEAR AND ROTARY ACTUATOR DRIVEN BY AN ELECTROMOTOR

摘要

The invention relates to a linear and rotary actuator that is driven by an electromotor, especially for reciprocating-screw plasticizers of injection molding machines. An injection unit for an injection molding machine comprises a linear actuator (3) that drives the reciprocating-screw plasticizer (2) in a lifting motion, and a rotary actuator (4) that drives the reciprocating-screw plasticizer in a rotating motion by means of an electromotor and that is coaxial to the linear actuator. A rotor (15) is rigidly linked with the reciprocating-screw plasticizer, not allowing neither lifting nor rotating motions, and is coupled with the stator of the rotary actuator via magnetic pole systems (16, 17) so as to transmit a torque. The aim of the invention is to provide an actuators that substantially reduce the inertia of masses effective during the injection stroke of the reciprocating-screw plasticizer and that do not require complicated sliding bearings that might negatively influence the transmission of torque. For this purpose, the rotor of the rotary actuator is mounted so as to be axially displaceable relative to the stator irrespective of its rotation. One of the stator- or rotor-mounted magnetic pole systems of the rotary actuator is extended relative to the other magnetic pole system corresponding to the stroke of the linear actuator while the housings (5) of the linear and the rotary actuator are firmly interlinked.