| 摘要 |
1,025,714. Tubular films. NATIONAL DISTILLERS & CHEMICAL CORPORATION. Oct. 10, 1962 [Oct. 10, 1961], No. 38406/62. Heading B5B. Tubular thermoplastic film is made by extruding a molten thermoplastic material through a die orifice formed by two parallel slits interconnected at each end and opposing sides of the tube are held apart for separate cooling by permitting air to enter the tube through the portion of the die which is between the two slits. Both the flat sheet portion and interconnecting bead portions of the tube may be of a substantially uniform guage, or one of the flat sheet portions may be of a gauge greater than that of the other, or the bead portions may be of a gaugesubstantially greater than that of either of the flat sheet portions. In apparatus as shown, the molten thermoplastic material passes through the extruder barrel 2 into the extrusion head 1 by way of conduit 51, and into the passageway 52. Thence the flow is divided by the fluid conduit element 68, to pass upwardly around the air blade 9 (Fig. 2, not shown) and outwardly from the continuous orifice formed by the air blade 9, die. lips 5 and 6, and deckle plates 61. Air blade 9 comprises two parallel sides 9a and 9b, each having semi-circular recesses at intervals therein, the recesses in the two sides being opposite each other so as to form a series of cylindrical air blade passageways 70 (Fig. 2, not shown). A chilled fluid, e.g. refrigerated air, is introduced into the conduit element 68 and is discharged by way of the air blade passageways 70 between the two sides of the film, so as to keep them apart and urge them into surface contact with the chill rolls 25. Rolls 25 are chilled by circulation of a refrigerated liquid, e.g. water, through the conduit system 35, 24, 36 and driven by motor 31 through the chain and sprocket system 28, the film passing between the rolls 25 to the nip rolls 41, 42. By means of bolts 62, 65, die lips 5 and 6 may be moved laterally to adjust the width of either side of the film. By means of bolts 84 (Fig. 2, not shown), the deckle plate elements 61 (Fig. 2, not shown) may be moved laterally to adjust the width of either end-portion of the film.
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