| 摘要 |
<p>The air inside a blown plastics tube which is continuously drawn as it is blown, flattened, longitudinally slit and then rolled up to form thin plastics sheet, is changed by incompletely flattened in the region where the tube is longitudinally slit so that the air within it can escape from the partly flattened tube through the slits. Pref. a controlled air gap is formed between the two sides of the partially flattened tube by two movable components which can be varied in relative position to determine the width of the gap. The cutting device, pref. two opposite cutting blades is mounted centrally between the movable components. The air is allowed to escape continuously, so that no extraction pipe needs to be mounted with inside the blowing head.</p> |
