Abstract: A die for co-extruding structural shapes is provided with a central cylindrical duct through which the molten polymeric material destined to constitute the central core of the structural shape flows, and a conical gap, coaxial with the central duct, into which the polymeric coating material is fed which will constitute the outer skin of the structural shape.

Abstract: An apparatus for sizing extruded plastics sections is proposed in which, in order to increase the heat transfer capacity between the hot plastics mass of the section and a cooling vehicle in a reduced space and to allow high production rates, there is interposed between metal block-type sizing gauges a cooling tank to be traversed by the section to be cooled between one sizing gauge portion and a subsequent sizing gauge portion. In this tank, which can also be placed under vacuum, the section is subjected to the action of a cooling fluid such as water or air which acts directly on its outer walls.