| 摘要 |
Aluminium panels curved in mutually orthogonal x, y and z dimensions are made by stretch forming. A former (34) for use in this process comprises a plurality of steel bars (60) extending generally in the y direction and mutually spaced apart in the x direction. The bars (60) are held in side rails (62) and (64), which are formed with holes (66) to receive the bars (60), and flexed over an intermediate rail (68). Thus each bar (60) is curved in a yz plane. The holes (66) and the seats for the bars on the intermediate rail (68) each lie on a curve in an xz plane. So located, the bars (60) combine to define an envelope which is curved in mutually orthogonal x, y and z dimensions. When an aluminium sheet is stretched over the former (34), it takes up the shape of this envelope. |
