Device and method for continuously producing an at least partly hollow shaft having a varying inner and/or outer diameter

A method for continuous production of an at least partially hollow shaft with a varying internal and/or external diameter, said method comprising the steps of:

• providing a cylindrical blank having a bore, which at least partially penetrates into said blank and forms a central cavity in the blank,
• clamping the blank in a clamping head, such that an opening of the central cavity is located on an end side of the blank facing away from the clamping head,
• axially moving the clamping head with the clamped blank toward a first position of the blank such that a first portion of the blank is aligned with radial forging tools that are symmetrically disposed about a forging axis,
• axially moving a counterholder or axially moving the clamping head such that a counterholder mandrel of the counterholder axially penetrates into the central cavity in the blank up to a defined stop, wherein the counterholder mandrel has an internal part and an external part and the clamped blank is supported by the external part,
• radially advancing the forging tools in a radial working direction toward the first portion of the blank,
• forging a first shaft portion with a first internal diameter in a region of the first portion of the blank, wherein the first internal diameter is defined by an external diameter of the external part,
• radially opening the forging tools,
• axially moving the external part out of the central cavity in the blank in a direction toward a base of the counterholder, wherein an end side of the blank is supported by way of the external part,
• axially moving the clamping head with the clamped blank toward a second position of the blank such that the internal part is located in a region of a second portion of the blank and only partially penetrates into the central cavity,
• radially advancing the forging tools toward the second portion of the blank,
• forging a second shaft portion with a second internal diameter in the region of the second portion of the blank, wherein the second internal diameter is defined by an external diameter of the internal part and defining a finished shaft,
• radially opening the forging tools,
• axially moving the internal part out of the central cavity in the blank in the direction toward the base of the counterholder, wherein the end side of the blank is released from the external part,
• axially removing the blank from the clamping head.