| 摘要 |
A rotor having at least one peripheral annular channel (24) is rotatable relative to a stator surface of a surrounding stationary housing to impel material in the channel from an inlet (28) through the housing, to a circumferentially spaced outlet (36), through which plasticised (liquid) material is discharged by pressure developed by the material being impelled against a first stationary surface (34) which projects into a channel downstream of the outlet (36). A second surface (40), upstream of the outlet (36), has a clearance with the walls of the channel (24) and restrains advance of (unmelted) material (39) in the centre of the channel while permitting liquid material (25) to be dragged towards the first surface (34). The channel space (46) between the first and second surfaces (34 and 40) enables the discharge pressure to be generated in an accumulated pool (42) of the liquid material. The second surface (40) may be provided on an extension along the channel of part of the member (32) which defines the first surface or may be provided on a further member (38), which may be of various different configurations, and may act as a scraper against one channel wall. <IMAGE>
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