| 摘要 |
1,120,075. Improvements in cooling tubular thermoplastic film. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 26 June, 1967, No. 29290/67. Heading B5B. In the manufacture of tubular thermoplastic films by extrusion of a polymer melt from an annular orifice, and cooling the extruded film with a gaseous cooling fluid supplied from a cooling ring surrounding the tube, an annular guide wall is mounted coaxially with the cooling ring, at least a portion of the guide wall being adjustable in a manner not affecting the size and position of the fluid discharge openings in the cooling ring, and adjustment means are provided for varying the position of the adjustable portion of the guide wall while maintaining the coaxial relationship thereof with the cooling ring. In one embodiment (Fig. 2) the guide wall 11 is composed of a large number of resilient trapezium shaped blade elements 28 mounted in circular arrangement, so that their non-parallel edges overlap, each blade being secured individually at its lower end to the cooling ring 19. An internally threaded ring 24 mounted on top of the cooling ring is in communication with an externally threaded adjustment ring 25, rotatable within the ring 24, and having an annular inner edge 27 against which rest the blade elements of the annular guide. Rotation of the ring 25 by means of a handle 29 causes the edge 27 to move in a vertical direction thereby allowing the blades to move outwards or inwards depending on the direction in which the ring is screwed. Cooling air supplied by a tube 16 is discharged through slits 22 and 23 in the cooling ring and flows through the annular passage between the guide wall and the surface of the tube, the annular passage comprising a restriction 17 forming a Venturi throat, the location and dimensions of which may be altered using the above apparatus. |
