Method for control of the thickness of extruded film

US7751923B2 · kind B2 · utility

Assignee

• Windmöller & Hölscher KG · DE

Inventors

• Lothar Koenig · Hemau, DE
• Bartholomeus Trommelen · Gronau, DE

Key dates

• Filing date: Dec 9, 2003
• Grant date: Jul 6, 2010
• Expiry date: Oct 13, 2024

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B29C2948/92923
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

A process for the automatic control of the thickness of extruded film lowers the deviations in the thickness of the film more quickly after the start of the extrusion process. The process includes the measurement of the thickness profile of the film just extruded by means of a thickness-measuring probe. The thickness-measuring probe is moved along the surface of the film substantially perpendicular to the conveying direction of the extruded film. The thickness-measuring probe records a thickness profile of the film for each measuring cycle at least over parts of the expansion of the film perpendicular to its conveying direction. While providing statistical values in relation to older measured values, the latest measured values during a predetermined time-frame at the start of the extrusion process are more heavily weighted by a computer than those measured during the normal operation.