Heat-exchange rolls and method of calendering and rolling including controlling the temperature of such heat exchange rolls
861,188. Electrically heated rolls. FARREL -BIRMINGHAM CO. Inc. April 17, 1959 [May, 2, 1958], No. 13135/59. Class 39 (3). [Also in Group XXXV]. A heat-exchange roll for use in calenders or rolling mills comprises one or more electrical heating coils 28a within the body of the roll 20 and a channel is provided between the roll body and the internal sleeve 28 for supporting the heaters for the passage of cooling air under pressure. The temperature of the roll can then be regulated by control of the heating current and control of the air blower. This control may be in response to thermocouples 40 provided in the body of the roll, and a circuit is described for automatically maintaining the roll at a desired temperature. The air blower inlet is shown at 29, and the direction of the air flow is reversed at the end of the channel between sleeve 28 and the roll body 20, so that the air flows back through the sleeve 28 and out through the sleeve 30. The roll is mounted at each end in a journal 26 and the leads to the heaters and thermocouples are connected to slip rings. A heat-insulating washer 33 is provided at each end of the roll body 20. Three electrical heating coils 28a are provided side by side and three thermocouples 40 are provided, equally spaced around the roll, but extending different distances into the body of the roll in order to sense the temperatures at three different locations.