| 摘要 |
<p>987,776. Stretching films and sheets. O. B. RASMUSSEN. Aug. 10, 1962 [Aug. 11, 19611, No. 30793/62. Headings B5A and B5B. Apparatus for the transverse stretching of film and sheet material 5, especially low pressure polyethylene or polypropylene, comprises a cross-fluted roller 6, two cross-beams 7, 8 or, alternatively rollers or rods (not shown), a pair of pulling rollers 9, 10 and a series of wheel-shaped members 11, or alternatively, ball-shaped members (not shown), which pass laterally across the film or sheet by means of an endless chain arrangement (not shown) in the direction of arrow 14. The action of the members 11 causes pressure points to repeatedly move transversely across the sheet material as the material passes through the zone, the pressure exerted being sufficient to permanently stretch longitudinally the sheet material as the material passes through the zone. Passage over the cross-fluted roller 6 causes a slight contraction of the film or sheet over the top of the flutes causing the formation of a series of short slipping lines 12 at about 45 degrees, and a slight pleating as indicated by lines 13. The wheel 11 displacing the sheet downwardly between the beams 7 and 8 causes local stretching and smoothing which spreads sideways in the direction of arrow 14 as the wheel passes across. When the wheel has passed the sheet or film returns to the original level and simultaneously, owing to the distension, a fine longitudinal pleating will be formed continuing across the beam 8. The original slipping line system now forms a dense pattern 14 which disappears together with the fine pleatings during a subsequent longitudinal stretching in known manner. In a modification, a pleating apparatus may be included following the cross-fluted roller. The apparatus is suitable for the cold-stretching of film or sheet material, especially of low-pressure polyethylene or polypropylene and for the preliminary treatment of film and sheet material which is to be used for producing fibres by splitting.</p> |
