Adjusting apparatus for roll threading die head

An adjusting apparatus for a roll threading die head with a head body having a plurality of threading rollers located on an imaginary circle concentrical to an axis of a cylindrical workpiece to be threaded, wherein the improvement comprises eccentric bearings which rotatably support the corresponding threading rollers at opposite ends of the rollers and which are rotatable about axes eccentric with respect to the axes of rotation of the respective threading rollers, and a rotor which simultaneously rotates the eccentric bearings about their axes by the same angular displacement wherein said rotor is comprised of front and rear annular plates which are interconnected together, said front and rear annular plates including elongated grooves therein, said eccentric bearings having flanges with pivot pins extending therefrom into said grooves.