Abstract: Internal high pressure forming at present takes place by exerting a pressure between sheet metal blanks fixed by a marginal weld. It has already been proposed to deform under high internal pressure sheet metal blanks merely placed on one another in a combined clamping and sealing die. Problems arise with regards to the sealing and material flow. Thus, to overcome the aforementioned disadvantages, the invention proposes a method for forming at least one workpiece under high liquid or hydraulic pressure, in which the workpiece, during pressure build-up, is initially marginally clamped in per se known manner and in the final phase of forming to the desired final shape of the workpiece (sizing) the marginal area of the workpiece is freed.

Abstract: For shaping small radii in edge and corner regions of preformed workpieces or blanks, the invention provides for a postforming of exclusively said edge and corner regions by high liquid pressure. For performing the method an apparatus has a die part (forming insert) with expansion spaces constructed in its edge and corner regions.