Patent ID: 8496460
Filing Date: 2013-07-30
Classification: B29C,B29K,B29L

Abstract:
1. A multilayer pipe extrusion die apparatus comprising: a first flow passageway having a first cross-sectional area and extending along a first flow direction parallel to a pipe production direction, the first cross-sectional area being substantially unchanged over the length of the first flow passageway; a second flow passageway connected to the first flow passageway, the second flow passageway having a second cross-sectional area substantially the same as the first cross-sectional area of the first flow passageway and extending along a second flow direction extending radially-outward from the first flow direction of the first flow passageway; and a frusto-conical passageway extending from the second flow passageway toward a third flow passageway downstream the frusto-conical passageway, wherein the third flow passageway extends to a dispensing outlet and includes a substantially constant width over a length of the third passageway; wherein the frusto-conical passageway is configured to choke the flow of melted material flowing from the first and second flow passageways substantially proximate to the dispensing outlet, to maintain substantially constant material flow properties along the first and second flow passageways.