Seal for piston screws in plastics injection and extrusion apparatus
US4966539A · kind A · utility
19Cited by
9References
4Claims
0Family size
Inventor
Key dates
| Filing date | Jul 18, 1988 |
| Grant date | Oct 30, 1990 |
| Priority date | — |
| Expiry date | Jul 18, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/789
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
An extruder screw of a plastic injection molding machine has a tip seal device at its forward end. The tip seal device has a body portion and a tapering tip portion, a circumferential sealing skirt is provided between the tip portion and the body portion. During extrusion, the pressure of molding material behind the skirt compresses it radially to allow for passage of the material through an extruder nozzle. When the screw is moved forwardly after extrusion, pressure of material forwardly of the skirt increases and expands the skirt radially into contact with the extruder barrel to form a seal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.