OVERLAPPING PLATE DETECTING DEVICE

PROBLEM TO BE SOLVED: To set a sensor in a range where it never makes contact with a detecting plate without reducing the detection precision of the sensor by setting a plurality of ultrasonic sensors close to a material load sensor, and comparing the displacement of count values of the ultrasonic sensors with a preset set value. SOLUTION: As plate thickness measuring ultrasonic sensor, upper and lower ultrasonic sensors 5W1 , 5W2 are arranged on a working side WD separated from each other with the same space on the basis of the pass line P of a carrying band, and upper and lower ultrasonic sensors 5D1 , 5D2 on a driving side DS separated from each other with the same distance. As a photoelectric material load sensor, working side and driving side material load sensors 6W, 6D are arranged on both sides of a V-shaped carrying table with a central material load sensor 6C as the top. The plate detection signals by the material load sensors 6C, 6W, 6D are inputted to a computing element to start the count of the ultrasonic sensors 5W1 , 5W2 , 5D1 , 5D2 , the count values are compared with a set value, and when the count values exceed the set value, an alarm is issued.