| 摘要 |
1318927 Expanding and guiding tubular film ESSO RESEARCH & ENG CO 30 Nov 1970 [22 Dec 1969] 56711/70 Heading B5B In a process for extruding a tubular film downwardly, expanding it, and passing it over a cooling mandrel before collection, the film is externally guided during the expansion step by a plurality of concentric annular pressure zones which exhibit a decreasing pressure gradient in the downward direction. The zones are provided by means of a series of annular orifices arranged in echelon. As described, a support plate 42 carries a fixed ring 24, and this supports three movable rings 22, 26, 28, which carry annular plates 78, 80, 82 respectively. The movable rings are pressure-sealed by 0-rings 110 and are kept from binding against each other by spring-biased studs 100. Ring 24 has two camtracks 90, 92 which run diagonally round a portion of the circumference. Followers 94, 96 and 98 engage in these tracks such that rotation of any movable ring by a handle (e.g. handle 8 as shown for ring 22) causes vertical movement of that ring. Each handle may be fixed in position after adjustment, as at 118, 116. Air is fed to the rings via annulus 76. The edges of the plates 78, 80, 82 preferably lie on a straight line in use, but may lie on an arc whose sagitta does not exceed 7À5% of the length of the chord subtending the arc. In one embodiment (Fig. 2, not shown) the mandrel includes a hollow, watercooled, film-contacting annulus, and is surrounded by a cooling ring which presses the film against the annulus by pressure derived from direct contact of the outside of the film with cooling water. |
