Draw-forming of stretchable thermoplastic material into hollow articles
US4256449A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 30, 1979 |
| Grant date | Mar 17, 1981 |
| Priority date | — |
| Expiry date | Jul 30, 1999 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C51/08
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Apparatus and method for draw molding elongated hollow articles from thermoplastic material which is desirably stretch moldable plastic sheet or film. The material is draw molded on an elongated mandrel. Draw ring means are operated cooperatively with the mandrel for drawing the thermoplastic material into an elongated hollow article. Gaseous jet stream doctoring means are operated during drawing for controlling the article wall thickness. The material may be drawn through a wiper ring through which the mandrel is moved with the thermoplastic material during draw molding in combination with subjecting the outer surface of the article being drawn to the action of the doctoring jet stream from an annular orifice. Internal fluid conditioning of the mandrel, as well as alternate negative pressure within the article during molding and stripping pressure from the mandrel into the article at conclusion of molding cycle are provided for. The draw molding is effected without clamping the thermoplastic material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.