JPS5572847A - Temperature control method for electric furnace for high-temperature tension tester - Google Patents

Abstract

PURPOSE: To exercise automatically PID control over heating zones of two layers eliminating a difference in temperature between both test pieces so that test pieces will rapidly be held at an even and high temperature, by exercising cascade control over the center heating zone of three- layer heating zones in accordance with a temperature in the center of test pieces and ambient temperature in the furnace.

CONSTITUTION: The detected temperature of center-part detection point 2 in the length direction of test piece 1 is negatively fed back to the input side of temperature compensator CO, and a detected temperature at center-part detection point 5 of heater HM for the center heating zone is also negatively fed back to the input side of temperature compensator CM to exercise cascade control over heater HM, so that test piece 1 will rapidly be held at a fixed high temperature. On the other hand, heaters HT and HB for both-side heating zones are brought under PID control through temperature compensators CT and CB, and power control circuits TT and TB according to temperature differences between detection points 2 and 4 on both sides of the test piece and detection point 3 in the center so as to eliminate the both- side temperature difference of test piece 1, so that test piece 1 will uniformly be heated. Therefore, automatic heating control is exercised to hold the test piece at an even and fixed high temperature in a short time.

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