Abstract: Forming die for manufacturing screw workpieces of a tube semi-product, e.g. rotors of single-spindle pumps. The function cavity of the forming dies consists of a guide part, a forming part, and a calibrating part. The guide part of the function cavity is formed by the intersection of a cylindrical surface and a helix, the forming part is formed by the intersection of a conical surface and a helix, and the calibrating part is of the shape of the helix of the final product. A minimum length of the guide part of the function cavity is equal to the diameter of the cylindrical surface, but the minimum length of the forming part as well as the length of the calibrating part of the function cavity is equal to one lead of the helix. The ratio of the diameter of the cylindrical surface of the guide part to the diameter of the helix is at least 1.1:1.

Abstract: Apparatus for radial shaping of rotors, stators, crankshafts, spindles and the like from an elongate seamless tube where a supporting ring performing a reciprocating motion according to an adjustable stroke of a connecting rod causes by way of rollers and guiding segments a reduction and increase of the radial distance of sliding shoes with forming jaws with respect to the formed object.