Inspection theory outline and sensor structure
A magnetization coil is used as an electromagnet by sending current through a magnetization coil. The magnetic field which occurred with the electromagnet is made to permeate the inside of spot welding.
The magnetic flux which occurred by the magnetic field is interrupted rapidly. It makes a detection arrangement coil generate induced electromotive force. I acquire this induced electromotive force as a detection signal.
Distribution of the amplitude permeability which the detection array coil acquired is made into a graph. This judges quantification of a nugget, and the existence of nugget.