Abstract: This invention relates to a die device for forming tube from a metal band, wherein the die comprises a long die block comprising, lengthwise and passing through it, a conduit comprising an inlet orifice of larger cross section and an outlet orifice of smaller cross section. The conduit converges from the inlet orifice towards the outlet orifice. At the level of the inlet orifice, the conduit is of a width slightly greater than that of said metal band. As the planar metal band passes through the conduit, it is formed by the interior surface, or generatrices, of the conduit into a tube of the desired configuration. Means are provided for creating tubes of differing cross-sectional shapes, such as a square, or a circular configuration. The die block is removably mounted on a carriage, which carriage is movable horizontally in front of a horizontal mandrel driven in rotation. The tube created by passage through the die block is wound around the mandrel.