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Flow channel wall
DE 198 31 540 C2; EP 99 392 764.6-2301; PCT/EP 99/04528

This is our latest and most progressive solution to manufacture an adjusted wall for a flow channel. Its geometry can be fine tuned very sensitively while the process is running . We developed a totally new production technology to integrate a partial multi-walled section into the interior of a flow channel. This technique is applicable for both slit dies and annular dies. In slit dies it will slowly replace the old membrane solution using spring steel sheets which had to be welded into the body of the die. The big advantage of this new technology is that there is no longer any welding necessary. Furthermore it can be designed precisely to the special application as the number of single walls which support each other and the thickness of the single individual walls can be varied in a vide range. We decided to proof the advantages of this new technology first by designing coextrusion feed blocks and test them in close co-operation with interested customers in lab lines and in production lines.

In the field of annular dies the new Flex Ring Technology which is applicable for pipe dies, for blown film dies and for dies used in the blow molding process opens up totally new possibilities in these processes. In the field of pipe extrusion there are already some production lines which run very successfully with a Flex Ring Die. By using Flex Ring Dies the thickness differences which remain after the die has been centered in an ideal way can easily be reduced while the line is running by simply adjusting the gap of the flow channel locally limited. The same is possible with dies for the blown films. Still in the developing phase is the use of Flex Ring Dies for the blow molding process. It is the goal to vary the thickness of the parison over its circumference in order to achieve an even thickness distribution in the final product although it has very different draw ratios over its surface.

Advantageous applications for such flow channels with a flexible wall segments are:

 •    Throttles to fine tune or to adjust the flow resistance of a flow channel in single- and

       multi-layer slit dies

•    Use in coextrusion feedblocks to adjust the thickness distribution over the width of
       individual
       layers
 •    In double walled sheet dies to reduce the thickness tolerances of the upper and lower wall
 •    In profile dies to optimise the wall thickness around the profile
 •    In controlled extrusion lines where the local flow resistance is automatically changed via
      small gear drives (see also „bank measuring system" and „device and process for controlling
      the bead size in the glazing rolls")

Publications:

Groß, H.: Latest Developments Concerning Slit Dies with Integrated Flexible Membrannes. Tagungshandbuch der ANTEC 2000, Orlando, Seite 61 – 65

Groß, H.: The Flex Ring Technology Opens up New Processing Posibilities in the Field of the Blow Molding Process. Tagungshandbuch der 16. PPS-Jahrestagung, 18 – 23 Juni 2000 in Schanghai, Seite 183 -184

Groß, H.: Membrantechnik zur Mehrschichtextrusion von Platten/Folien, Rohren und Profilen. Tagungshandbuch Heilbronner Kunststoff Symposium 2000, 19. – 20 Sept. 2000, Kapitel E7

Groß, H.: The Third Generation of Membrane Dies futher Improves to Fine Tune the Mass Flow Distribution in Extrusion Dies. Tagungshandbuch der 16. PPS-Jahrestagung, 18 – 23 Juni 2000 in Shanghai, Seite 185 –186

Groß, H.: New Technology to Vary the Thickness Distribution of the Parison in Circumferential Direction during the Blow Molding Process. Tagungshandbuch bzw. CD der ANTEC 2001, 07. – 11. Mai 2001 in Dallas,

Groß, H.: New Technology to Reduce Wall thickness Tolerances in Pipes. Tagungshandbuch bzw. CD der ANTEC 2001, 07. – 11. Mai 2001 in Dallas,

Groß, H.: Flexringtechnologie eröffnet neue verfahrenstechnische Möglichkeiten in der Extrusion. Tagungshandbuch der Fachtagung „Neuigkeiten in der Extrusion“ des Süddeutschen Kunststoff Zentrums in Würzburg, 09. – 10. Mai 2001, Seite I1 – I14

Groß, H.: Neuheiten in der Extrusion: Weiterentwicklungen in der Werkzeugtechnik und bei Meßsystemen. Zeitschrift Kunststoffe, Jahrgang 91, Heft 9/2001, Seite 82 - 85

Groß, H.: Innovations in Extrusion: Further Developments in Die Technology and in Measuring Systems. Zeitschrift Kunststoffe plast europe, Vol. 91, Issue 9/2001, Page 28 - 29