| 摘要 |
<p>A strip (2) of material used to make filter tips is processed on equipment incorporating one or more pairs of rollers (11, 12, 13, 14) placed along a set path (P) , each composed of a top roller (11, 13) with a helical thread (15) , and an anvil roller (12, 14) , by which the fibres of the strip (2) are stretched and pulled longitudinally and/or transversely; when seen in section, the profile (16) of the helical thread (15) is such that each turn presents a crest portion (17) merged with two flanks (19) by way of smooth and/ or rounded portions (20) , so that when the strip (2) of filter material is engaged by the crest portion (17) , it will not be brought into contact with sharp corner edges.</p> |
