| 摘要 |
826,008. Extrusion machines for rubber. BRITISH INSULATED CALLENDER'S CABLES Ltd. Oct. 5, 1956 [Aug. 19, 1955], No. 23959/55. Class 87(2). [Also in Group XXXV] The temperature of a rubber stock being mechanically worked is controlled by cooling the stock by a liquid medium at a temperature below its boiling point, effecting a continuous small transfer of heat from an independent source to the cooling medium, and regulating the transfer to obtain the desired temperature of the stock. In a machine for extruding rubber in which the stock is fed through a barrel 1, Fig. 1, to an extrusion die (not shown) by a screw 2 by which it is mechanically worked, a liquid cooling medium, e.g. water, is passed through groups of cooling tubes 4 within a jacket 3 surrounding the barrel 1. The stock in the barrel 1 is maintained at the desired temperature by a thermocouple 18 which controls the current supply to the element 17 of an electric heater surrounding the cooling jacket 3. A thermocouple 19, Fig. 4, maintained at the desired temperature of the stock, and the thermocouple 18 are connected to a D.C. amplifier 20 differentially so that when the thermocouples are at the same temperature there are equal currents in output coils 30, 31 which are arranged as opposed field windings of an electric motor 25. The latter is adapted to drive through reduction gearing a rheostat (not shown) connected in series with the heating element 17. As the temperature of the thermocouple 18 rises above or falls below that of the thermocouple 19 the resultant field due to the windings 30, 31 drives the motor 25 to decrease or increase the current through the rheostat. The motor 25 is oeprated intermittently the armature thereof being energized through switches 28 operated by clockwork mechanism repeatedly to remain open and closed for controlled time intervals, whereby the minimum temperature differential between the thermocouples 18, 19 required to adjust the rheostat may be varied. When it is desired to maintain different parts along the length of the barrel 1 at differing temperatures a plurality of cooling devices and surrounding heating devices may be provided.
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