Patent ID: 6629353
Filing Date: 2003-10-07
Classification: B21D,Y10T

Abstract:
A method for producing a dish of rounded shape, open at its top, of a weldable aluminum alloy, particularly for producing the bottom of a tank, the method comprising:(a) providing a mold having an interior face cavity that corresponds to the shape of said dish, said mold being closed at its top and open at an opposite end from said top; (b) forming a blank in the shape of a cone frustum by bending and welding a flat piece of an untempered aluminum alloy having a shape of a portion of an annulus; (c) inserting said blank completely into said mold, so that: said blank has an initial position that is concentric with said mold, an exterior frustoconical face of said blank faces said interior face of said cavity, a small base of said blank rests on said interior face of said cavity near the top of said mold, and a large base of said blank is close to said interior face of said cavity near the opening of said mold; (d) arranging a deformable pressing wall peripherally inside said blank, against an interior face of said blank and near the small base; (e) applying heat and pressure to said blank and said deformable pressing wall during a first phase, to cause: said blank and said deformable pressing wall in contact therewith to bend toward the interior face of said cavity, and said blank to progress toward the top of said mold and conform to the shape of said cavity's interior face; (f) halting progression of said blank and said deformable pressing wall toward the top of said mold, when said blank and said deformable pressing wall reach a predetermined position of conformity with said cavity; (g) applying said heat and pressure during a second phase to: mold said exterior face of said blank to the shape of said interior face of said cavity, and press said deformable pressing wall against said interior face of said blank and thereby contribute to molding said exterior face of said blank; (h) extracting said blank, which is formed into said rounded dish having an opening at the top, from the mold.