| 摘要 |
<p>Apparatus for manufacturing a tubular film of lacunary structure, of the type in which the tubular film (2), extruded from a circular extrusion slit (1), receives a series of perforations (5, 5') disposed according to a helical path along the walls of the tubular film, the latter being for this purpose extruded by passing between two non- concentric circular rings, including an outer ring (3) constituting the outer wall of the extrusion slit and an inner ring (6), at least one of the two rings being moveable and simulated into a nutational movement about an axis colinear with the axis of the fixed ring, the movement of the moveable circular ring bringing it into permanent contact with the wall of the fixed ring at a point of contact which moves continuously around the perimeter of the fixed ring, one of the rings comprising, on its face in contact with the other ring, indentations suitable for perforating the film in the zone of contact between the two rings, and the apparatus is characterised in that the rings are disposed in such a way in relation to each other that the action of incision and perforation of the moveable ring engaging with the fixed ring is carried out immediately downstream from the extrusion slit (1) and on the film (2) which is no longer held against the wall of the fixed ring. <IMAGE></p> |
