Rotor for an electric machine

An electric machine comprising

• a stator,
• a rotor comprising:
• a rotor core, and
• a rotor shaft,
• wherein the rotor core is fixed on the rotor shaft, and
• wherein the rotor shaft has, at least in some regions, a non-circular cross-section so that, at least in some regions, a plurality of axially extending channels are formed between the rotor core and a lateral surface of the rotor shaft,
• wherein at least one region with the non-circular cross-section of the rotor shaft has a forging skin, wherein the forging skin is produced by radial forging without subsequent machining, so that the region with the non-circular cross-section of the rotor shaft has the forging skin, and
• a cooling circuit,
• wherein the axially extending channels of the rotor define the cooling circuit.

A method for producing a rotor comprising a rotor core and a rotor shaft, wherein the rotor core is fixed on the rotor shaft, wherein the rotor shaft has, at least in some regions, a non-circular cross-section so that, at least in some regions, a plurality of axially extending channels are formed between the rotor core and a lateral surface of the rotor shaft, the method comprising:

• providing a blank;
• rotating the blank;
• producing the at least one region with non-circular cross-section of the rotor shaft by radial forging the blank without subsequent machining, wherein the blank is not rotated in a final radial forging operation, and
• producing a forging skin on at least one region with the non-circular cross-section by radial forging without subsequent machining.