Method for shaping workpieces from thermoplastics

US5151241A · kind A · utility

Assignee

• Max-Planck-Gesellschaft zur Föderung der Wissenschaften e.V. · US

Inventors

• Dieter Maier · Rettenberg, DE
• Harald Egner · Stuttgart, DE
• Stefan Fröhlich · Mutlangen, DE
• Jurgen Hoffmann · Untersiggenthal, CH

Key dates

• Filing date: May 22, 1991
• Grant date: Sep 29, 1992
• Expiry date: May 22, 2011

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S425/014
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

A method and device for shaping tubular workpieces from thermoplastic placs is disclosed. In the method, the workpiece to be shaped is inserted into a mold, heat is applied from the interior of the workpiece to heat the workpiece to the softening temperature of the plastic, this temperature is maintained until the workpiece assumes the shape of the mold, and the workpiece is left in the mold until it has cooled off. A flexible heating core is used to apply heat to the interior of the workpiece. The heating core has an insulating jacket with a sliding layer on its outer wall and a heating conductor winding located within the insulating jacket. A stress relief extends lengthwise in the middle of the heating core and outward of the heating core at one end. A receptacle is provided at the other end of the heating core for the stress relief.