| 摘要 |
1,202,961. Making tubular film; sizing dies. IMPERIAL CHEMICAL INDUSTRIES Ltd. 19 May, 1969 [17 June, 1968], No. 28681/68. Headings B5A and B5B. Apparatus for producing tubular film comprises a vacuum sizing die and a " contraction die " connected together to form a continuous passage therethrough. The vacuum die disclosed has a highly polished central passage 1 at each end of which is a ring of holes 16, 17 connected to a source of vacuum via chambers 7, 8, pipes 10, 11 and outlet 13. The centre of the passage is cooled, e.g. by water, circulated through zone 9 via pipes 14, 15. The " contraction die " has a central passage 23 accurately aligned with that of the vacuum die and which decreases in diameter towards the outlet, but which may have the walls of its final portion parallel. This die allows the tube to contract while preventing water entering the vacuum die from a cooling bath in which the whole may be submerged. The manufacture of tubes of poly- (4-methylpentene-1) is exemplified, and the taper on the contraction die for a 1 inch dia. tube of this polymer is about 0À01 inch. |
