APPARATUS FOR MEASURING THICKNESS OF SOLIDIFIED CAST PIECE

摘要

PURPOSE:To provide an accurate apparatus which is operated safely in a severe environment, by attaching an electromagnetic ultrasonic wave generator and an electromagnetic ultrasonic wave receiver to a detector for the total thickness of a cast piece. CONSTITUTION:A pulse signal is conducted through a generating coil 3 by a pulse generator 8, and a pulse magnetic field as shown by an arrow 17 is generated. An electromotive force is induced on the surface of a cast piece 7 and an eddy current 18 is generated. A pulse electromagnetic force is generated by the mutual action with the pulse magnetic fields of the arrow 17. Ultrasonic wave vibration is generated on the surface of a cast piece 7 by said force. The electromagnetic ultrasonic wave generated on the surface of the cast piece 7 advances in the direction of an arrow 19 in the cast piece 7. When the wave reaches the other surface, vibration is generated on the surface of the cast piece 7. An electromotive force is generated on the surface of the cast piece 7 by the mutual action of the vibration and the magnetic field, which is generated by an exciting coil 5 excited by an exciting power source 9. Said electromotive force is amplified by an amplifier 10. A part required on the time axis is taken by a gate circuit 11 and sent to a transmitted-time measuring circuit 12. The thickness of the cast piece 7 is measured based on the time difference between the input signal from the gate circuit and the pulse output timing signal.