| 摘要 |
<p>A metering device is disclosed for use in a plastics moulding machine having a mould cavity (16), relatively movable platens (10,12) and a means (26) for feeding a plastics melt into the cavity. The metering device comprises a heated block (22) interposed between the feeding means (26) and the mould cavity (16). A cylinder (34) with a moving piston (37) is formed in the block (22). A first passage (28,32) in the block (22) connects the cylinder (34) to the feeding means (26) and a second passage (32,40) connects the cylinder (34) to the mould cavity (16). Valves (30) in the passages (28,32,40) enable the cylinder (34) to be filled by the feeding means (26) without the melt entering the mould cavity (16) and subsequently enable the desired dose of plastics melt, when ejected from the cylinder (34) by the piston (37), to flow from the cylinder (34) to the mould cavity (16) without being returned to the feeding means (26).</p> |
