Patent ID: 6849220

Claim:
A method of manufacturing a rotor for a helical screw machine that includes a metal shaft and helical lobes mutually separated by intermediate grooves, said metal shaft having a barrel surface, comprising the steps of providing the shaft with a blind axially extending passageway; connecting the passageway with the barrel surface of the shaft by means of at least one outwardly extending channel such that said at least one channel is located generally in the middle of the mould when the shaft is inserted therein; inserting the rotor shaft into a mould that includes a barrel wall and two mutually spaced end-walls that include respective rotor shaft receiving openings, said openings embracing the rotor shaft at least in a generally sealing fashion; heating the mould and the shaft to the curing temperature of the polymer; pressing polymer forming materials into the axially extending passageway at an over pressure of at least one bar to deliver polymer-forming materials to the mould; maintaining the barrel wall of the mould at said curing temperature until the polymer has cured; and removing the rotor from the mould.