The invention relates to a shaping shoulder and to a device for producing longitudinally shaped webs with an open or closed cross-section and at least one zone inside the web, in which the cross-section curves outwards. Said webs are for example tubular bags comprising longitudinal folds, tubular bags with one or more chambers formed by subdivisions in a longitudinal direction, in addition to webs that are corrugated longitudinally. The shaping shoulder consists of one or more shoulder sections (2) and a prism section (3), which combine to form a three-dimensional shaping edge (5), with zones of the prism section curving outwards. The curvature of the shaping edge sections belonging to said zones, viewed from the centre of the web towards the edge of the web, slopes in the opposite direction to the displacement of the web and the corresponding zones of the shoulder section curve away from the outlet of the tube.