摘要 |
Developing a volume in a shooting pot reservoir (28) is achieved through the selective coupling and de-coupling of an injection piston (34) to a plunger (38). Following successive injection ( FIG. 5a ) and hold phases ( FIG. 5b ) of an injection molding process ( FIG. 5 ), the runner and channel system is partially de-compressed ( FIG. 5c ) by drawing back together, over a short distance, the plunger (38) and the injection pressure (34) as one unit. The injection piston is then mechanically de-coupled from the plunger ( FIG. 5e ), with the injection piston (34) withdrawn to essentially its final shot position, but minus a customary packing distance (8). Plastic melt (100), extruded into a shooting pot (28) positioned in front of the plunger (38), is permitted to push the plunger backwards, but now with minimal work expenditure. When the plunger again contacts ( FIG. 5f ) the injection piston (34), melt pressure now causes both units to be moved back to reach a final shot size volume. Finally, the injection piston (34) drives the plunger (38) forward to eject melt accumulated within the shooting pot (28).
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