Method and apparatus for making tubes

Abstract

In a method of making a tube a sheet metal blank. having opposite longitudinal flanks is placed in a die of a shaping tool. At least one of the longitudinal flanks of the sheet metal is provided with a contact projection suitable for resistance pressure welding. The blank is pressed into a U-shaped cavity of the cavity by a ram to shape the blank into a U-shaped configuration which is then shaped between an upper mold and a lower mold of a molding press into a tubular profile with the longitudinal flanks confronting one another. The upper mold has in an area of the confronting longitudinal flanks oppositely poled electrode strips which are insulated against one another. During subsequent welding operation, the contact projection on the one longitudinal flank is welded to the confronting longitudinal flank as a result of welding heat generated through introduction of an electric current via the electrode strips into the longitudinal flanks and a clamping pressure by which the upper and lower molds are held together.

Dependencies are inferred from the claim text.