| 摘要 |
For open bore injection molding, the apparatus includes in combination a hot bushing, a cold mold, and a thin-walled seal. The bushing is adapted to convey molten material from a hot manifold to an article formation cavity in the mold. The mold defines a bore extending into its upper surface, and a gate at the bottom of the bore which communicates with the article formation cavity. The bushing at least partially fits within, and in spaced relation to, the periphery of the bore. The bushing includes an unobstructed lumen therethrough which opens into its lower end and is generally aligned with the gate. The bushing also defines a depressed portion in its outer surface located in closely spaced, circumferential relation to the opening of the lumen into its lower end. The thin-walled seal is formed of metallic material having low thermal conductivity, and has a generally arc-shaped cross-section. Further, the seal engages the depressed portion of the outer surface of the bushing, and has a small portion compressively urged against the surfaces defining the bore when the bushing is located in the bore. The seal closes off the gap between the bushing and the mold, while at the same time minimizing the conduction of heat therebetween.
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