Patent ID: 8812168

Claim:
A temperature measuring method of measuring the temperature of a steel sheet, said temperature measuring method comprising: disposing a reference plate provided with a temperature controller opposite to an objective steel sheet; directly measuring the reference plate temperature T 2 of the reference plate by a thermometer other than a radiation pyrometer; training a radiation pyrometer on the objective steel sheet at an angle such that it receives radiation energy that has been alternately reflected by the reference plate and the objective steel sheet once or twice; measuring the radiosity of the objective steel sheet by the radiation pyrometer; using a temperature obtained by converting the radiosity into a temperature of a blackbody that radiate energy equivalent to the radiosity as a radiosity temperature T g ; calculating an approximate temperature T 1 ′ of the steel sheet by using: T 1 ′=T g +K ( T g −T 2 ) (1) where K is a correction coefficient determined on the basis of the respective radiosities of the reference plate and the objective steel sheet obtained by measurement or mentioned in a literature; executing a control operation by the temperature controller to make the reference plate temperature T 2 coincide with the approximate temperature T 1 ′ of the steel sheet temperature; and using the approximate temperature T 1 ′ as the temperature of the objective steel sheet.