Method and machine for making a finned body

A machine for making a finned body (12) from a blank (12′) of a high-ductility material, comprising

• a blank holding device (17) for supporting the blank (12′),
• a forming tool (18) which is mounted for rotation about a tool axis (L) and displacement transversely to the tool axis (L) and comprising a set of flat circular spaced-apart forming discs (19) centered on and disposed side by side at fixed intervals along the tool axis (L) and in planes perpendicular thereto,
• a motor for rotationally driving the forming tool (18),
• a displacement mechanism (22, 23) for relatively displacing the forming tool (18) and the blank holding device (17) transversely to the tool axis (L) during rotation of the forming tool to cause the forming tool to move cyclically over a surface of the blank (12′), and
• means for maintaining the forming discs (19) in a constant orientation and axial position relative to the blank (12′),
• wherein the displacement mechanism comprises a first hydraulic actuator (22) connected to the forming tool (18) to apply to it a displacement force (FA) directed toward a blank held by the blank holding device (17) and a second hydraulic actuator (23) connected to the forming tool (18) to apply to it an oppositely directed force (FB) which is smaller than the displacement force (FA),
• wherein the second actuator (23) is adapted to apply the oppositely directed force (FB) with a magnitude thereof added to a differential force (FC) acting on the blank wherein the sum of force (FB) and (FC) is of the same order of magnitude as the displacement force (FA), and wherein said force (FA) is many times said force (FC).