摘要 |
<p>A novel multiple-plastic stream co-extruder and method, as for injection-molding cavities, in which the extruder is internally provided therewithin and therealong with a restrictor or throttle pin, rod or element that forces combined plastic material streams, formed with an interior core stream encased in outer and inner stream layers, into corresponding concentric annular flow stream layers that are ultimately split transversely in opposite directions into a cavity gated to the extruder, and with the core stream at a region of zero gradient in the transverse flow velocity profile within the extruder and cavity.</p> |