Abstract: 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.

Abstract: A device for arranging ferromagnetic components a preset distance from one another including an electromagnet defining a pole gap wherein a nonuniform attractive magnetic field is formed with a gradient directed along its axis of symmetry. At least one of the pole pieces of the electromagnet is provided with a ferromagnetic rack adapted to move in the plane in which it lies. The plane of the rack is substantially normal to the direction of the magnetic field gradient. The rack includes teeth which are spaced apart in accordance with a desired preset distances between ferromagnetic componets. The device also comprises a means for feeding ferromagnetic components into the magnetic field, in the direction of its gradient.