| 摘要 |
A blown film process in which optimum quality film is produced by automatically controlling either the frost line position on the the tubular on blown film or the temperature in an area between the frost line and the extrusion die head. A sensing device (30) monitors the temperature in a control area between a frost line (28) and an extrusion die head (14). The signal produced is fed to a controller (32) and to a temperature reading instrument (36). The controller (32) is set to continually compare the signal received from the sensing device (30) with a pre-determined control temperature for the control area. If there is any difference between these temperatures the controller (32) operates a butterfly valve (46) which either increases or decreases the rate of flow of air from a compressor (50) to a cooling ring (52), thereby correcting the temperature in the control area to the desired control temperature at which optimum quality film is produced. <IMAGE>
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