| 摘要 |
Apparatus for dispensing a mixture of mutually reactive liquids, such as a hardenable plastic foam, comprises a metal housing with a plastic mixing chamber disposed in the housing and having a bore therethrough in which a purging rod reciprocates to clean reactive mixture from the bore. The reactive liquids are separately introduced into the bore through the mixing chamber via valve assemblies whose metal housings extend through the plastic mixing chamber and terminate at the bore. The purging rod retracts rearwardly into a scraper that is immediately behind the inlet openings for the liquids, the scraper being disposed in a recess in the rear of the plastic mixing chamber. The plastic mixing chamber is compressed rearwardly, so that it seals against the valve housings and the scraper. Also, the valve housings have a crush fit with the plastic of the mixing chamber, to augment the seal. Air nucleation can be provided, by feeding the air radially inwardly through the wall of the bore between the liquid inlet openings and the scraper. |
