Method and mechanical arrangement for producing a wall profile on a plastically deformable hollow body wall

A mechanical arrangement for producing a wall profile on an inside of a plastically deformable hollow body wall of a hollow body with a cavity, delimited by the hollow body wall, which is open on at least one side thus forming a cavity opening, wherein the mechanical arrangement comprises a forming device for forming the hollow body wall, the forming device comprising:

• a forming mandrel which has a forming mandrel profile and which is configured to be arranged in an interior of the cavity of the hollow body such that the forming mandrel extends with the forming mandrel profile along the hollow body wall,
• a forming die which is provided with a die opening and which is configured to be arranged on an outside of the hollow body and
• a forming drive, by which the forming die arranged on the outside of the hollow body wall can be moved with a forming movement along the hollow body wall passing through the die opening relative to the hollow body wall and relative to the forming mandrel, wherein the forming die is configured to produce the wall profile on the inside of the hollow body wall by plasticizing material of the hollow body wall due to the forming movement of the forming die, and the forming mandrel profile is reproduced on the inside of the hollow body wall as the wall profile,
• wherein the forming mandrel has a mandrel portion with an enlarged cross-section and a mandrel portion with a reduced cross-section, wherein the mandrel portion having an enlarged cross-section and the mandrel portion having a reduced cross-section each have a forming mandrel profile portion and wherein the mandrel portion having an enlarged cross-section has a cross-section oversize compared to the mandrel portion having a reduced cross-section,
• wherein the forming mandrel is configured to be arranged in the interior of the cavity of the hollow body in such a way that the forming mandrel extends, with the mandrel portion having an enlarged cross-section, at a level of a first longitudinal portion (l1) of the hollow body wall and, with the mandrel portion having a reduced cross-section, at a level of a second longitudinal portion (l2) of the hollow body wall following the first longitudinal portion (l1) of the hollow body wall along the hollow body wall, and
• wherein the forming die is movable by the forming drive during the forming movement along the hollow body wall relative to the mandrel portion having an enlarged cross-section and relative to the mandrel portion having a reduced cross-section of the forming mandrel, such that, due to the forming movement of the forming die,
• on the inside of the first longitudinal portion (l1) of the hollow body wall, the forming mandrel profile portion of the enlarged mandrel portion having an enlarged cross-section is reproduced as a first wall profile portion of the wall profile, and
• on the inside of the second longitudinal portion (l2) of the hollow body wall, the forming mandrel profile portion of the mandrel portion having a reduced cross-section is reproduced as a second wall profile portion of the wall profile.