| 摘要 |
1,208,032. Film casting apparatus. CROWN ZELLERBACH CORP. 30 April, 1968 [31 July, 1967], No. 20477/68. Heading B5B. In a casting device wherein a continuous stream of film-forming material, e.g. polyethylene, is fed from a slot 6 on to a moving casting surface 3 and a vacuum is applied to the trailing face 9 of the material, the suction pressure across the width of the material is balanced by means comprising two independent ducts 41, one at each end portion of the material, each duct being connected to a source of vacuum for withdrawing air which has infiltered behind the material at these end portions and whereby the space between the ducts is in indirect communication with the vacuum only through the end portions. A moving casting-belt may be used instead of the roller illustrated. A pad 28 may be provided to prevent ingress of air from the rear. The ducts may be provided with independent dampers 43. |
