| 摘要 |
Multi-station reaction injection molding apparatus, and method, are disclosed for in-place foaming of polymerizable resins in articles advanced along a production line, as for example in the manufacture of insulated appliance housings such as refrigerator cabinets. The articles are selectively diverted from a feed conveyor, one to each of a plurality of pour stations adjacent the feed conveyor. At the stations, injection of foamable resin mix is accomplished by reaction injection type molding heads which combine at least two liquid resin components. These components are suitably catalyzed to react and form a cellular or foamed polymerized resin. The liquid components are separately but continuously supplied to respective supply manifolds to which all of the heads are connected in parallel by shunting ducts. Excess unmixed liquid components are returned separately from each of the heads through recycle shunting ducts to respective recycle manifolds. Thus division of the component flows takes place among all of the heads, whereby to maintain temperature and compositional uniformity of the components as close to the point of mixing and injection as possible. Control means selectively determine the order in which each pour station injects foam mix into an article. That same control further produces a metered output of the respective components at elevated pressure sufficient to effect reaction injection mixing at the selected head, while simultaneously interrupting the flow of all components at all of the other heads. Reduction of off-ratio mixing problems, and greater uniformity of foam properties, are thus achieved. |
