Process for producing connecting member shanks, such as hinges for window and door frames, formed of cylindrical sections of different diameter, with continuous even screw thread, that is with constant pitch

A method of forming a thread convolution with uniform pitch on a shank with at least two coaxial and essentially cylindrical portions of different diameters, the thread convolution on the shank being a leading face disposed at a first angle to the central axis of the shank, said method comprising the steps of providing a blank having two coaxial and essentially cylindrical portions connected by a sloping portion with the surface inclined at said first angle to the common axis of the two cylindrical portions, rolling said blank between a rotating chaser having two coaxial thread forming surfaces radially spaced apart by a distance equaling the difference in radius of said two different diameter portions of said blank and a fixed curved chaser having two thread forming surfaces radially spaced apart by a distance equal to the difference in the radius of said two different diameter portions of said blank, the larger diameter of said rotating chaser having a larger surface speed than the smaller diameter portion of said rotating chaser and being disposed in engagement with the smaller diameter portion of said blank, and guiding said blank during said rolling by abutting said sloping surface of said blank against sloping thread forming surfaces of said rotating chaser and said fixed chaser which connect said two thread forming surfaces of said rotating chaser and said fixed chaser, respectively, and which are parallel with said sloping surface of said blank to form a continuous uniform pitch thread convolution over and between the two essentially cylindrical portions of the blank.