| 摘要 |
1275253 Sizing thermoplastic tubing JAMES A JOBLING & CO Ltd 15 May 1969 [30 May 1968] 26060/68 Heading B5A [Also in Division C1] An elongate tube 13 of thermoplastic material is passed, while still in hot plastic condition, through a first gas filled zone 4 while maintaining a pressure within the tubing 10-25 inch w.g. higher than that in zone 4 and a low volume flow rate of gas through the zone, so as to control the outer configuration of the tube, and then through a second zone 5 wherein a pressure differential of less than 10 inches w.g. is maintained together with a high volume flow rate of gas through the zone, so as to cool the tube. The tube may be supported on rollers 2A, 2B, which may be of graphite. The gas flow is produced by partially evacuating each zone via outlets 18, 19 while allowing gas to enter via apertures 15, these apertures preferably being provided with shims 16 (not shown) to control the flow rate. The boxes constituting zones 4, 5 may be moved relative to each other, and the rollers 2, 2A, 2B may be moved vertically. Reference has been directed by the Comptroller to Specification 1,202,630. |
