An apparatus for forming a metal tubular preform in the form of an elongated metal tubular member having a substantially box-shaped cross section along an extension thereof, said apparatus comprising: a mold assembly (10), comprising a structure (12) of movable upper mold, and a second structure (14, 16) of mold; said mold structures (12, 14, 16) being cooperative to define a mold cavity (52) having a cross-sectional configuration in the form of a closed box; securing structures (26, 28) located at opposite ends of said mold cavity (52), and constructed and arranged to securely secure separate portions of the metal tubular preform (40), said structures (26) presenting , 28) securing securing surfaces (34, 36) that define an overall oval surface configuration, which is in accordance with a generally oval outer peripheral surface of the metal tubular preform (40), and a tube end hitch structure , constructed and arranged to substantially engage and seal the opposite ends of the metal tubular preform (40), said tube end engagement structure having a generally oval external surface configuration that conforms to the generically oval internal peripheral surface of the preform metallic tubular, characterized in that said second mold structure comprises a mold structure (14) infe movable rior, and a fixed mold structure (16), said movable lower mold structure (14) having an opening (42), and the fixed mold structure (16) being received inside said opening (42) , whereby the relative movement between said mobile upper mold structure (12) towards its engagement with said second mold structure (14, 16) closes said mold cavity (52), and once said cavity (52) When the mold has been closed, the movement of said mobile upper mold structure (12) with respect to said fixed mold structure (16) progressively reduces the cross-sectional area of said mold cavity (52).
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