Rotor core manufacturing method, and rotor core molding system therefore

A rotor core manufacturing method for molding permanent magnets in an unmolded rotor core to provide a molded rotor core for an electric motor, wherein an unmolded rotor core comprises a shaft of the electric motor and a rotor core body having a central through-hole extending along and around a longitudinal axis of the rotor core body, magnet cavities distributed around the longitudinal axis and permanent magnets inserted in the magnet cavities, the shaft of the electric motor is arranged in the central through-hole, the magnet cavities and the central through-hole extend along the longitudinal axis between opposing first and second rotor core body ends of the rotor core body, and the magnet cavities have an opening at one or both of the first and second rotor core body ends for filling of the magnet cavities with a fluid molding material, wherein the shaft projects from the central through-hole of the rotor core body with respect to one or both of the rotor core body ends, wherein a molded rotor core comprises the rotor core body having the permanent magnets fixed in the magnet cavities by a cured molding material in the magnet cavities, and

• wherein the method comprises
• providing an unmolded rotor core;
• providing a rotor core pressure molding system having a first mold and a second mold configured and arranged, in an open configuration of the first mold and the second mold, to insert the unmolded rotor core in between the first and second molds with the first and second rotor core body ends directed along a clamping direction towards respective ones of the first and second molds, and, in a closed configuration of the first mold and the second mold, to clamp the rotor core body of the unmolded rotor core between the first and second molds for providing pressure along the clamping direction onto the clamped rotor core body by the first and second molds, and to provide a fluid molding material into the magnet cavities of the unmolded rotor core clamped between the first and second molds, wherein the first mold and the second mold are configured to receive therein the shaft that projects from the central through-hole of the rotor core body with respect to the rotor core body ends, the first mold comprises a recess or an opening therein for receiving the shaft projecting from the central through hole of the rotor core body with respect to the respective rotor core body end and the recess or the opening in the first mold is dimensioned so that the shaft does not contact the first mold to exert a force in the clamping direction when the rotor core is clamped between the first mold and the second mold, and the second mold comprises a recess or an opening therein for receiving the shaft projecting from the central through hole of the rotor core body with respect to the respective rotor core body end and the recess or the opening in the second mold is dimensioned so that the shaft does not contact the second mold to exert a force in the clamping direction when the rotor core is clamped between the first mold and the second mold;
• inserting the unmolded rotor core between the first mold and the second mold of the rotor core molding system in the open configuration of the first and second molds with the first and second rotor core body ends directed towards the respective first and second molds;
• closing the first and second molds from the open configuration to the closed configuration by moving the first and second molds towards one another to clamp the rotor core body of the unmolded rotor core with a predetermined pressure in between the first and second molds in the closed configuration;
• providing a fluid molding material into the magnet cavities of the unmolded rotor core body clamped between the first and second molds;
• letting the fluid molding material cure within the magnet cavities to provide a molded rotor core;
• opening the first and second molds to the open configuration by moving the first and second molds away from one another;
• and
• removing the molded rotor core from between the first and second molds.