Controlling heat treating furnaces.

摘要

A method and apparatus for determining the correct temperature of a heated coil of sheet material and for using said measurement to control a heat treating furnace. The method includes providing a spot of heat resistant material having a known and constant emissivity on an uneven edge of the coil, the material of the spot remaining on peaks of the uneven edge. The constant emissivity of the spot is independent of that of the edge, which edge changes and is substantially less than the true temperature of the edge. The coil is heated and the spot emits infrared energy in an amount that is substantially representative of the correct temperature of the coil. This infrared energy is sensed by an infrared detector aimed at the spot, the output of the energy being indicative of the true temperature of the edge and of the coil mass after it attains the temperature of the edge. <IMAGE>