| 摘要 |
<p>An extruder screw tip with an eccentric head and bevelled faces at each end of an integral neck for locating against a sleeve valve which is slightly shorter than the neck. Used esp. for injection moulding machines where reciprocation of the screw is used to fill the mould. The sleeve may be removed over the head of the tip by an axial shift when the screw is advanced sufficiently clear of the barrel, without needing to extract the screw completely and remove the sleeve over the screw root, yet the sleeve is captive when the head is in the barrel. Sleeves and/or heads can therefore be readily substd. to suit different melt characteristics or shot sizes. The melt has a clear peth past the shallow sides of the head, is less prone to blocking or delayed remelting than designs where the melt passes the head through drilled passages or surface channels. The tip is more robust than designs involving separate root, neck and head components coupled (screwed) together.</p> |
