Process for the production of hollow bodies from thermoplastic material

US5409647A · kind A · utility

Assignee

• Krupp Kautex Maschinenbau GmbH · DE

Inventors

• Erich Kiefer · Bonn, DE
• Peter Klusener · Bonn, DE

Key dates

• Filing date: Jun 13, 1991
• Grant date: Apr 25, 1995
• Expiry date: Jun 13, 2011

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B29C2948/92657
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

In that process for the production of hollow bodies from thermoplastic material by extrusion blow molding in which discontinuously extruded preforms are expanded in a blow molding mold, at least during that part of the filling phase which is typical of such a process, for an extrusion head, the distance covered by an ejection piston associated with a storage chamber and the speed at which the ejection piston is displaced within the storage chamber by the plasticised material are detected and compared by a central control and regulating device to the respective reference values. On the basis of the result of the comparison operation at least one operating parameter of the process, for example the delivery output of the extruder or the extent of the emptying strike movement of the ejection piston can then be adapted while still in the same working cycle in such a way that substantially the required preform volume is ejected.