Process and apparatus for producing hollow bodies from thermoplastic material

US4828783A · kind A · utility

Assignee

• Krupp Corpoplast Maschinenbau GmbH · DE

Inventors

• Peter Albrecht · Hamburg, DE
• Wolfgang Reymann · Hamburg, DE
• Klaus Vogel · Gondelsheim, DE
• Hermann Werner · Hamburg, DE

Key dates

• Filing date: Feb 5, 1987
• Grant date: May 9, 1989
• Expiry date: Feb 5, 2007

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B29C53/20
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

In the production of hollow bodies from oriented thermoplastic material, a cylindrical portion of a heated hollow preform is stretched, with a simultaneous reduction in the wall thickness thereof, at a starting temperature below the vitreous transition temperature of the material. A mandrel is positioned in the preform to support it during stretching, the outside diameter of the mandrel corresponding to the inside diameter of the preform. Directly before the mandrel is inserted into the preform the preform is subjected to re-alignment to adapt at least the cross-sectional shape of the mouth opening of the preform to the cross-section of the mandrel. The re-aligning operation is effected by inserting the preform into a sleeve adjoining a drawing ring for carrying out the stretching operation.