| 摘要 |
The present invention relates to a screw (27) for use in, for example, an injection molding machine or an extruder. The screw (27) includes a screw shaft (39) having a thread (41) spirally positioned about the screw shaft (39) so as to form a plurality of flights (43, 45, 47). The screw (27) has three zones (29, 31, 33), a feeding zone (29), a compression zone (31) and a metering zone (33), and the depth and pitch of the flights (43, 45, 47) of the screw (27) are designed based upon the material to be used in the screw (27) so that the difference in the ratio of the actual flow to the theoretical drag flow of material in the feeding zone (29) and the ratio of the actual flow to the theoretical drag flow of material in the metering zone (33) is less than 0.2, preferably less than 0.1, and more preferably less than 0.05. This design results in a screw (27) which has a balanced mass flow, and thus a constant pressure gain along the screw without pressure peaks.
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