| 摘要 |
The quantity of oil used as a heat transfer medium, is controlled continuously. It can be varied between minimum and maximum flowrates An Independent claim is included for corresponding equipment with a conventional cooling spiral (1) and pump (2) for the oil, and an electrical heating element. In the new design, a variable-speed motor (3) drives the pump and/or a proportional valve alters the quantity of oil through a cooling zone. Preferred features: A similar variant based on the foregoing method is claimed. Temperature of the circulating oil is held approximately constant by regulation of coolant quantity. The quantity of coolant for the oil used for heat transfer, is controlled as a function of oil temperature. The oil temperature is raised above the coolant temperature for the minimal flowrate during heating phases. The quantity of oil is varied by changing the speed of the pump drive, and/or by using a proportional valve. The cross section of the extruder cylinder in at least one of the heating zones, is approximately elliptical or oval. |
