Process for the extrusion of a plastic foil having small variations in thickness

US4013745A · kind A · utility

Assignee

• Dynamit Nobel GmbH · DE

Inventors

• Hans Brinkmann · Troisdorf, DE
• Gottfried Eisele
• Helmut Gormar · Weimar, DE
• Horst Pabst · Sankt Augustin, DE
• Helmut J. Putz
• Hans-Jurgen Schrick
• Uwe Sommermeyer · Troisdorf, DE

Key dates

• Filing date: May 20, 1975
• Grant date: Mar 22, 1977
• Expiry date: May 20, 1995

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02W30/62
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

A process for extruding a film having small variations in thickness by regulating the quantities fed to a worm press and by regulating the extrusion process. Marginal strips and waste products of extruded film are re-processed by returning these materials, slicing them and directly weighing them before being fed to the filling bin of the screw press. In order to regulate the quantities fed to the screw press, the weighed material per unit of time is continually subtracted from a nominal value set by a volume regulator associated with the raw material seeder devices. The filling degree of the screw press is measured as the mass pressure between the screw press and a constant volume pump such that the filling degree is maintained constant during the extrusion process.