an apparatus for the manufacture of a thermoplastic blown film is provided having a blower head for extruding a film tube of a thermoplastic material . an annular ring is provided for blowing a cooling gas on an outside surface of the film tube to solidify the film tube . this cooling gas is directed in a flow direction parallel to a wall of the film tube . the cooling gas is drawn off the tube by means of a suction ring positioned around the tube prior to flattening the tube to form a film tube .