| 摘要 |
<p>A tool which is used to make rows of perforations in a running web of paper or the like has a rotary holder and a flat blade which is removably secured to the holder so that one of its longitudinal edge faces extends beyond the periphery of the holder. Such one longitudinal edge face has a row of perforating teeth and the blade has an elastically deformable portion which extends lengthwise of the one longitudinal edge portion to enable at least some of the perforating teeth to yield if they engage a hard surface while the row of teeth bulges outwardly in the region between the ends of the one longitudinal edge face. The elastically deformable portion can have one or more rows of slots or one or more corrugations. If the elastically deformable portion has two rows of slots, the slots in the row which is nearer to the perforating teeth partially overlap the neighboring slots of the adjacent row. The elastically deformable portion contributes to longer useful life of the blade because it enables some or all of the perforating teeth to yield in response to stresses which act against the one longitudinal edge face in a direction toward the other longitudinal edge face or vice versa.</p> |
