| 摘要 |
1442661 Automatic control of temperature CROMPTON & KNOWLES CORP 10 Oct 1973 [13 Dec 1972] 47366/73 Heading G3R In order to reduce thermal inertia effects and overshooting in the control of an extruder barrel temperature, the extruder barrel 12, Fig. 2, with liner 13 is surrounded by a shell 16 of a material, e.g. aluminium, having a total heat capacity (i.e. the product of the specific heat of the material and weight) of not less than 0À5 times and not more than 1À5 times that of the barrel e.g. steel. Probes 28, 32 produce electrical output proportional to the temperature of the barrel and shell respectively. A unit 34 compares the average of the two outputs, as a measure of the instantaneous average of the two temperatures sensed; with a set value to produce an error signal. The error signal is used to selectively actuate, via a respective relay switch (R 1 ) (R 2 ) Fig. 3, (not shown), either a solenoid valve (26) controlling the supply of coolant (e.g. water) through tubes 18 in the shell, or, an electrical heating element 20 whereby to maintain the barrel temperature substantially constant within a tolerance range. More weight may be given to the barrel temperature by - (a) amplifying the barrel probe output, (b) having one or more additional barrel probes or (c) using a barrel probe having a higher output/ degree temperature than the shell probe. |
