Ramped stiffener and apparatus and method for forming the same

A die tool for forming a C-section component having radiused shoulders, the die tool comprising:

• first and second outer dies, each outer die having a truncated conical portion, a flange portion, and an outer die radiused portion between the flange portion and the conical portion, the first and second outer dies being symmetrically disposed to one another along a common axis such that each flange portion is outermost, and a cylindrical outer support die located between the first and second outer dies;
• and
• first and second inner dies, each inner die comprising a disc having a substantially conical surface, a circumferential surface, and an inner die radiused portion between the conical surface and the circumferential surface, the first and second inner dies being symmetrically opposed to one another along a common axis such that the conical surfaces face outwardly, and a cylindrical inner support die located between the first and second inner dies, wherein:
• the first and second inner dies and inner support die are arranged to be disposed between the flange portions of the first and second outer dies and are spaced apart there from to define a cavity corresponding to the desired cross-section of the C-section component to be formed;
• and
• the radiused portions of the inner and outer dies have a radius of curvature that varies about the circumference of the inner and outer dies;
• the inner and outer dies are rotatable such that the radius of curvature of the radiused shoulders of the cavity varies as the dies are rotated.