Intermittent multi-layer multi-parison extrusion head
AssigneeHoover Universal, Inc.
InventorMichael Hirschberger
Life of this patent
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Abstract
A multi-layer, multi-parison extrusion head in which nearly identical parisons are extruded from each extrusion station of the head when operated in an intermittent mode. Resin passages are provided within the extrusion head for supplying each of the resins to each extrusion station with the passages configured in a manner such that the ratio of resin volume for one resin in the passages for a given extrusion station compared to the volume of a second resin in the flow passages to the same extrusion station is the same for all extrusion stations while the volumes of resins feeding each station are not equal. As a result, a relatively simple configuration of passages is provided without requiring all of the passages to be of equal length.
Claims17
An apparatus for intermittent multiple layer multiple parison extrusion comprising:
- an extrusion head;
- means forming multiple extrusion stations within said extrusion head each having a lengthwise axis with the axes of said multiple stations being arranged coplanar and parallel with one another forming a longitudinal array of said extrusion stations within said head, said stations each extruding parisons of multiple concentric layers of thermoplastic resins;
- and
- passage means within said extrusion head for feeding resins to said stations, said passage means being configured to produce substantially equal ratios of resin volume for one resin layer to another resin layer for each station while the resin volume in said passage means for each layer is not equal for all stations.
Apparatus for multiple layer extrusion of resin for producing multiple intermediate articles comprising:
- an extrusion head;
- a plurality of extrusion stations within said extrusion head and each having a lengthwise axis with the axes of each station being arranged coplanar and parallel with one another forming a longitudinal array of said extrusion stations within said head, said stations extruding multiple concentric layers of thermoplastic resins;
- individual passage means within said extrusion head for feeding each resin separately to said stations, said passage means including for each resin an inlet sprue for communication with a source of molten resin, a runner extending longitudinally through said extrusion head and gates connecting each station to said runner, the lengths of said passage means from each said inlet sprue to each said extrusion station being symmetrical relative to each said inlet sprue;
- and
- said passage means being configured to produce substantially equal ratios of resin volume for one resin layer to another resin layer for each station while the resin volume in said passage means for each layer is not equal for all stations.
Dependencies are inferred from the claim text.