Metering and mixing of multi-component plastics
US4865226A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 14, 1988 |
| Grant date | Sep 12, 1989 |
| Priority date | — |
| Expiry date | Apr 14, 2008 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB01F2101/2805
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method and apparatus for metering and mixing multi-component plastics, in particular polyurethane, in which two or more hydraulic piston and cylinder units (A.sub.1 and A.sub.2) for each component, operate periodically by a balanced procedure. The pressure for the second piston and cylinder unit which takes over metering is equilibrated, before the beginning of the metering procedure, with the pressure of the first piston and cylinder unit which is in the process of metering. Switching from one piston and cylinder unit to the other (e.g. from A.sub.1 to A.sub.2) takes place in such a way that metering is taken over by the second piston and cylinder units at the same time as the first piston and cylinder unit is switched off. This is achieved by providing a pilot valve which has zero overlap and inevitably releases the component stream from the first piston and cylinder unit at the same time as the other piston and cylinder unit is switched off. Pressurization and pressure equilibration are effected by a hydraulic control apparatus which is incorporated in the hydraulic loop of the volume stream and automatically equilibrates the initial pressure with the metering pressure. This p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.