| 摘要 |
<p>The sleeve is in the form of a metallic tube, around which paper, metal or synthetic materials in strip, film, or sheet form can be rolled up. The tube may be made as a helical strip with smooth longitudinal corrugations or ribs, such that the adjacent coil of the strip overlaps at least along its edges. Adjacent coils may overlap by half the width of each strip, so that the wall of the tube has two layers (5,6). The corrugations may have flat heads (1), and may have rectangular, trapezoidal or round cross sections.</p> |
