| 摘要 |
Apparatus for making corrugated flexible tubing such as the suction hose used in a vacuum cleaner comprises an extruder which extrudes tubular plastic material with annular corrugations, followed by a higher-speed haul-off device, a heater, a cooler, and a lower speed haul-off device, all placed to act on the corrugated tube as the latter is passing over a mandrel, so that the corrugations become compressed to a close-pitched condition by the speed differential of the haul-off devices, the condition being set by the action of the heater and cooler. |
