Rotor axle of a high speed permanent magnet machine

A rotor axle of a high speed permanent magnet machine including a first part and a second part, both manufactured from a magnetically non-conducting material and including an inner end and an outer end for being axially interconnected one after the other by the inner ends to constitute an integral rotor axle, the outer ends including bearing structures to fit the rotor axle with bearings, and a cylindrical and solid permanent magnet which is coaxial with the first part and the second part in between them and magnetized perpendicularly to the axial direction of the cylinder, characterized in that the inner end of the first part of the rotor axle includes a cylindrical external surface with an external thread and that the inner end of the second part includes a cylinder sleeve, of which the internal base part corresponds in shape to the cylindrical permanent magnet so as to constitute a space for the permanent magnet, and of which the internal lining has an internal thread corresponding to the external thread of the first part, so that when the first part and the second part are concentrically rotated together one after the other in the axial direction, the permanent magnet is provided in its space between the parts.