Rizhsky Politekhnichesky Institut

Gennady N Alexeev

Vasily V Ardentov

Viktor S Fastritsky

Jury B Florinsky

Laimonis T Vingris

Viktor I Plotnikov

Leonid A Rodnevsky

A method of and apparatus for nondestructive testing of spot welds by producing in a test weld high and low frequency electromagnetic fields to induce eddy currents in the weld zone. The difference between the phase values of the resultant electromagnetic field intensities is indicative of the quality of the weld. The apparatus includes an eddy current transducer, high and low-frequency measuring channels, an indicator, and a controlled commutator for alternate connection of the eddy current transducer to the low-frequency measuring channel or to the high-frequency measuring channel. A memory unit is provided for storing the output signal of the high-frequency measuring channel, and a comparator is provided for comparing the signal stored in the memory unit with the output signal of the low-frequency measuring channel. A control unit alternately generates signals for simultaneously connecting the eddy current transducer to the high-frequency measuring channel and for storing the output signal of the high-frequency measuring channel in the memory unit, and signals for simultaneously connecting the eddy current transducer to the low-frequency measuring channel, and for comparing the signal of the low-frequency measuring channel with the signal stored in the memory unit.

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Gennady N Alexeev