Process for producing hollow bodies from thermoplastic material

US4847032A · kind A · utility

Assignee

• Krupp Corpoplast Maschinenbau GmbH · DE

Inventors

• Peter Albrecht · Hamburg, DE
• Adolf Appel
• Karl-Heinz Balkau · Oststeinbek, DE
• Edward Clar · Hamburg, DE
• Claus Horwege · Hamburg, DE
• Wolfgang Reymann · Hamburg, DE
• Klaus Vogel · Gondelsheim, DE
• Walter Wiedenfeld · Hamburg, DE

Key dates

• Filing date: Sep 15, 1988
• Grant date: Jul 11, 1989
• Expiry date: Sep 15, 2008

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B29C55/30
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

A process for producing hollow bodies from oriented thermoplastic material wherein a cylindrical portion of a heated hollow preform which has a bottom thereon is subjected to stretching at a starting temperature which is below the vitreous transition temperature of the thermoplastic material, with the wall thickness of the preform being reduced in the stretching operation. Prior to the stretching operation the preform is heated in the portion in which the stretching effect begins, to a temperature higher than in the portion adjoining same. Stretching is preferably effected along the axis of the preform at different rates such that in the portion of the preform at which stretching begins, stretching is effected at a lower rate than in the portion adjoining same in the stretching direction.