Extruder for the manufacture of a synthetic resin foil in the shape of a serpentine strip
AssigneeProost en Brandt N.V.
InventorFranciscus Elbertus Mulder
Life of this patent
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Abstract
Synthetic resin extruder comprising a rotatable extrusion head surrounded by a hollow ring rigidly secured, the interior of the ring communicating with a controllable supply of air for the head, said ring having an outer sliding face, in which are provided a number of passages equally spaced apart and closed by non-return valves having a portion projecting out of the sliding face, said face co-operating with a spring-controlled stationary shoe with a depression being provided with an air supply and the bottom of the depression co-operating with the valves to urge these into the open position.
Claims12
An extruder for the manufacture of a synthetic resin foil in the shape of a serpentine strip, said extruder comprising a rotatable extrusion head and a terminal for the controllable supply of air to the extrusion head in order to maintain a given excess pressure inside the forming strip of synthetic resin, characterized in that the rotatable extrusion head includes a hollow ring rotating with the head, the interior of said ring communicating with the air supply terminal for the head, in that an outer wall of the ring has a plurality of passages equally spaced apart in the circumferential direction and closed by non-return valves urged in the outward direction by spring force against the associated seats, said valves having a portion projecting out of the outer surface of said wall in the closed state, in that the outer surface of said wall being constructed in the form of a sliding face, with which sliding face cooperates a stationary shoe having a depression, which shoe is spring pressed against said sliding face and the edges of which shoe co-operate in sealing fashion with the sliding face, said depression being provided with an air supply terminal, and in that the shoe engages the projecting portions of those valves lying beneath the shoe in order to urge such valves into the open position, the depression covering in the circumferential direction a distance at least corresponding with the distance between two passages plus twice the diameter of said passages.
In an extruding system for synthetic resin, a rotatable extrusion head defining a circumferentially extending extrusion opening, means for feeding synthetic resin to said rotatable extrusion head to issue through said extrusion opening in the form of a tube, flattening means spaced from said rotatable extrusion head for flattening said tube whereby that section of the tube between said rotatable extrusion head and said flattening means defines a closed chamber, and inflating means for maintaining fluid pressure within said closed chamber whereby to attain a desired width of the flattened tube, the improvement wherein:
- said inflating means includes a circumferentially extending portion on said rotatable extrusion head defining a fluid manifold communicating through said rotatable extrusion head with said closed chamber, said portion presenting a circumferentially extending exterior surface provided with circumferentially spaced openings communicating with said fluid manifold, a check valve means associated with each of said openings and projecting therethrough for normally closing said openings, a nonrotatable shoe bearing upon said exterior surface and cooperable with said check valve means sequentially to open them as the extrusion head rotates with respect to said shoe, and fluid conduit means connected with said shoe for communication with said manifold through the sequentially opened check valve means to maintain said fluid pressure within said closed chamber.
Dependencies are inferred from the claim text.