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Converging flow of polymer melts in extrusion dies
Author(s) -
Cogswell F. N.
Publication year - 1972
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760120111
Subject(s) - extrusion , materials science , laminar flow , pressure drop , die (integrated circuit) , volumetric flow rate , die swell , flow (mathematics) , mechanics , composite material , mechanical engineering , engineering , physics , nanotechnology
Practical extrusion processes often involve geometrically complex dies. Such dies are usually tapered, or streamlined, to achieve maximum output rate under conditions of laminar flow. These converging flows may be analysed in terms of their extensional and simple shear components to calculate the relationships between volume flow rate, pressure drop, and post extrusion swelling. The analysis can also be extended to cover the free convergence as fluid flows from a reservior into a die. Comparisons between predicted and observed data for a series of coni‐cylindrical dies suggest that using this approach the pressure drop/flow rate relationship can be predicted within ±20% and the swell ratio/flow rate relationship within ±10%. Similar treatments have been in use for the last three years in solving such complex flow problems as radial flow in injection moulding and two‐dimensional annular convergence in blow moulding dies.