| 摘要 |
A method of forming a compound curvature metal skin from a sheet metal blank comprising the steps of: •providing a blank (1) defining at least a sector of a truncated cone having a central axis of symmetry, a leading edge and a trailing edge; • providing an arcuate or annular punch (4) substantially corresponding in shape to an inner surface of the compound curvature metal skin and having an outer surface, a leading edge and an inner surface; • gripping the leading edge of the blank (1) between mating faces of a first blank holding means (6) located on a first side of the punch (4) adjacent the inner face of the punch; gripping the trailing edge of the blank (1) between mating faces of a second blank holding (8) means located on a second side of the punch (4, opposite to said first side and adjacent the outer face of the punch; • displacing the first and second blank holding means (6,8) with respect to the punch (4) in a single direction to draw the blank (1) over the punch (4) while permitting the blank (1) to flow between mating surfaces of at least one of the first and second blank holding means (6,8), comprising the steps of displacing each of the first and second blank holding means (6,8) with respect to the punch by different amounts and at different rates. |
