| 摘要 |
A conveying screw comprises a long, cylindrical rotor 1 rotatable within a stator 2, and a propelling thread 5 is formed on the rotor and extends from one end of it to the other. At least two barrier threads 18-20 are also formed on the rotor, where they are located in axial sequence relative to each other. Each barrier thread is of wider pitch than the propelling thread 5, and each succeeding barrier thread (e.g. 19, 20) is of wider pitch than the barrier thread (e.g. 18, 19) that it succeeds, whereby the interaction of the combination of the propelling thread 5 and each succeeding barrier thread (e.g. 19,20) exercises a stronger mixing and/or pressurising effect upon the material being conveyed than did the combination of the propelling thread with the preceding (e.g. 18, 19) barrier thread. The barrier threads (e.g. 43, 59) may be in the form of a series of aligned barrier elements separated by small gaps (54). <IMAGE>
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