Abnormal measurement detection device and method for infrared radiation thermometer

A measurement abnormality detection method for an infrared radiation thermometer for measuring a casting mold comprising:

• preparing a dummy lens placed around an objective lens of the thermometer and arranged close to the objective lens and above the mold, so as to be more susceptible to adherence of contaminants emitted from the mold and thus to more contamination than the objective lens, a received light quantity measurement device, and a determination device connected to the received light quantity measurement device;
• projecting light to the dummy lens at predetermined intervals or at a predetermined timing, receiving a light reflected by the dummy lens, and measuring a received light quantity with the received light quantity measurement device;
• and
• calculating an attenuation rate of the projected light on the basis of the measured received light quantity, estimating a degree of contamination of the dummy lens on the basis of the calculated attenuation rate, and judging a necessity of warning for contamination of the objective lens on the basis of the degree of contamination of the dummy lens with the determination device.

A measurement abnormality detection method for an infrared radiation thermometer for measuring a casting mold comprising:

• preparing a thermoelectric thermometer for measuring temperature of a dummy black body point set in a cone hole existing on an inner surface of a cavity of the mold as a part having a shape absorbing infrared radiation or a part most close in shape characteristics to a black body in the mold and a determination device connected to the infrared radiation thermometer and the thermoelectric thermometer;
• measuring temperature of the dummy black body point with the infrared radiation thermometer and the thermoelectric thermometer;
• and
• obtaining the temperatures measured by the thermoelectric thermometer and by the infrared radiation thermometer, detecting measurement abnormality on the basis of a difference between these measured temperatures, and judging, when the measurement abnormality is detected, whether a defect exists in the infrared radiation thermometer or the thermoelectric thermometer on the basis of a relation between the temperatures measured by the thermoelectric thermometer and by the infrared radiation thermometer.