Method for producing a polygonal shaft

A method for producing the shaft, which is partially polygonal on the outer periphery, by means of radial forging comprising the following steps:

• provision of a cylindrical blank with a passage opening at least partially penetrating this blank and forming the central cavity of the blank (extruded blank closed at one end);
• clamping of the blank in the clamping head of the radial forging device so that an opening of the central cavity lies on an end face of the blank facing away from the clamping head;
• axial movement of the clamping head with the clamped blank to a first portion of the blank, axial advance of a counterhold so that a counterhold mandrel, namely an inner part and an outer part of the counterhold mandrel, axially completely penetrates the central cavity of the blank up to a defined stop, wherein the blank is preloaded via the outer part);
• radial advance of the forging hammers to the first portion of the blank);
• round forging of the first portion of the blank into a first shaft portion with a first inner diameter and a first outer diameter, wherein the blank rotates;
• radial release of the first shaft portion by the forging hammers;
• axial movement of the outer part of the counterhold mandrel in the direction towards the base of the counterhold out of the central cavity of the blank, wherein the end face of the blank is preloaded via the outer part;
• axial movement of the clamping head (10) with the clamped blank to a second portion of the blank so that an inner part lies in the region of the second portion and only partially penetrates the cavity;
• radial advance of the forging hammers to the second portion of the blank;
• round forging of the second portion of the blank into a second shaft portion with a second inner diameter and a second outer diameter, wherein the blank rotates;
• radial release of the second shaft portion by the forging hammers,
• axial movement of the inner part in the direction towards the base of the counterhold out of the central cavity of the blank, wherein the end face of the blank is still preloaded via the outer part;
• axial movement of the clamping head and counterhold with the clamped blank to the first shaft portion;
• radial advance of the forging hammers to the first shaft portion,
• polygonal forging of the first shaft portion, wherein the blank is not subjected to a rotation speed, i.e. does not rotate;
• and
• radial release of the first shaft portion by the forging hammers.