Browse Prior Art Database

DIE DESIGN FOR PIPE EXTRUSION AGAINST SAGGING

IP.com Disclosure Number: IPCOM000239604D
Publication Date: 2014-Nov-18
Document File: 2 page(s) / 94K

Publishing Venue

The IP.com Prior Art Database

Abstract

The cooling of plastic pipe is done via external cooling stations in several steps along the horizontal production line. The material solidifies from the outside into the pipe material. It is important to note that that the internal surface of the material is in a molten state for a significant period of time until this also solidifies by crystallization. During the period when the material exits the die until the material solidifies at the internal surface, the molten material will flow down ward. This melt flow down the inner circumference of the pipe after it comes out of the die and before it becomes solid during pipe extrusion due to gravity force. This so called sagging effect is especially challenging for large diameter heavy wall pipe extrusion.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 57% of the total text.

Page 01 of 2

Die Design for Pipe Extrusion Against Sagging

The importance of cooling in plastics pipe extrusion was recently presented at the Antec 2014 by Weiss et all1.The cooling of plastic pipe is done via external cooling stations in several steps along the horizontal production line. The material solidifies from the outside into the pipe material. It is important to note that that the internal surface of the material is in a molten state for a significant period of time until this also solidifies by crystallization.

During the period when the material exits the die until the material solidifies at the internal surface, the molten material will flow down ward. This melt flow down the inner circumference of the pipe after it comes out of the die and before it becomes solid during pipe extrusion due to gravity force. This so called sagging effect is especially challenging for large diameter heavy wall pipe extrusion. The major sagging effect of thinner top and thicker bottom thickness can be limited via the position of the central die core. The incumbent method of correction is to position the central circular die core off-center (lower).

Graphic 1 shows sagging

1 Antec 2014 : COOLING SIMULATION FOR THE PREDICTION OF QUALITY PROPERTIES AND PRODUCTION COSTS OF SEMI-FINISHED EXTRUDED PRODUCTS LIKE PIPES; Patrick Weiss, Gregor Hiesgen, Kenny Saul and Martin Spitz, SHS plus GmbH, Oberhausen, Germany

1


Page 02 of 2

This publication solves the pipe wall thickness non-uniformity...