Induction-type thickness gauge for sheet and foil - has probe head on each side of moving workpiece, one with a temp. sensing element e.g. a thermistor

摘要

The foil and sheet thickness measuring device provides continuous measurement of a moving workpiece. The gauge consists of two probe heads, one each side of the moving sheet or foil (1). One of the heads has a small cut-out in which is placed a temp. sensing element such as a thermistor. The space is also ventilated by an air line. This draws air away from the area in the immediate vicinity of the foil. The output of the sensor (8) is a function of the foil temp. Current induced in a pick-up coil (7) from oscillations produced in an induction coil (6) is a function of the foil thickness. This current is amplified (14) and rectified (15) and a multiplier (16) compensates for the variations of temp. The multiplier output is connected to a comparator (18) to which a reference signal is applied (19). An indicator (20) shows the variation of thickness from a nominal value.