| 摘要 |
<p>Perforations are made in a sheet material consisting of synthetic fibres, esp. non-woven fibres, with the aid of >=1 indented blade which is heated. The blade is rotated around an axis whilst the sheet of fibrous material follows a path at right angles to this axis. In the perforating zone, the fibrous sheet is tensioned between two rollers. At least one of the rollers is supported by a device such as a jack. This is linked to the driving mechanism for the sheet, so that when the sheet is stopped, it is withdrawn out of the range of the blade. Arrangement enables the use of reinforcements of synthetic fibrous material on conventional multiwall sack machines, ensuring that when tension is applied, the sheet of non-woven synthetic fibres tears across the perforations as does the paper, etc.</p> |
