Abstract: In a blow-head for producing tubular film from thermoplastic molten material and comprising a housing with a central supply conduit for the molten material, distributing passages radiating from the supply conduit to a respective distributing helix of an insert member, and means for internally cooling the blown film, said cooling means comprising concentric air inlet and outlet passages extending axially of the housing and each connected to at least one inlet tube and one outlet tube, respectively, the said tubes being disposed between adjacent said radiating distributing passages and extending to the exterior of the housing, provision is made for forming the film of at least two layers having different properties by making the said insert member tubular and providing in it at least one coaxial further insert formed with further distributing helices each of which is fed with further molten material from a further supply conduit through further distributing passages, the said insert member terminating in an ann

Abstract: Apparatus for air-cooling blown tubular thermoplastic film downstream of a position where the film has already solidified comprises a ring having air outlets directed onto the tubular film, the ring comprising a plurality of blow pipes which are pivotally interconnected in pairs at adjacent ends and hinged at their other ends to holding elements which are radially adjustable with respect to the tubular film. The hinge axes at the holding elements are disposed so that the blow pipes form a uniform polygon and the lengths of the individual pipes is such that, when the holding elements are at their radially outermost adjustment, the pipes extend in an obtuse angled zig-zag line circumferentially of the tubular film.

Abstract: In a blow-head for producing tubular film from thermoplastic molten material and comrising a housing with a central supply conduit for the molten material and distributing passages radiating from the supply conduit to a respective distributing helix of an insert member, means for internally cooling the blown film comprise concentric air inlet and outlet passages extending axially of the housing and each connected to at least one inlet tube and one outlet tube, respectively, the tubes being disposed between adjacent said radiating distributing passages and extending to the exterior of the housing.