| 摘要 |
<p>A gun (10) for mixing and dispensing plural component plastic materials, for example, polyurethane foam, is provided with a purging device operable independently of the foam mixing and dispensing mechanism. The purging device comprises a rod (68), normally positioned rearwardly of the foam component inlet orifices and mixing chamber (34), the rod being selectively actuable independently of the foam mixing and dispensing operations, by a two way air cylinder (72) controlled by the gun operator. Purging elements, for example, compressible spheres (58) or plugs of a plastic material such as styrene are fed under pressure to seat in a position rearwardly of the foam component inlet orifices and mixing chamber. Upon selective actuation of the rod (68), one of the spheres (58) is forced through the mixing chamber (34) to purge any residual foam components by a scraping action.</p> |
