Institut Dr. Foerster Gmbh & Co. Kg

Institut Dr. Friedrich Forster Prufgeratebau Gmbh & Co Kg

Heinrich Braun

Helmut Reitz

Helmut Schwarz

In a method for detecting near-surface defects in a test sample consisting at least partly of a ferromagnetic material, a test volume of the test sample is magnetized and scanned for the detection of magnetic leakage fields caused by defects. The test volume is magnetized by means of a magnetic constant field and simultaneously by means of a magnetic alternating field superposed on the constant field. Leakage field test devices suitable for carrying out the method are described.

Method and device for detecting near-surface defects by means of magnetic leakage flux measurement

A device for testing elongated objects, particularly wires, optionally with cross-sectional irregularities, which has a rotating test head traversed by the object and on which is provided a probe, particularly an eddy current probe, provided on rotary probe holding means and guided on circular paths about the object. For the change of the radial spacing between the object and the probe with the test head rotating, externally controllable e.g. by a sensor for irregularities, the device has a switching device with two inherently stable switching states, whereof one can correspond to a testing position near the object and another to a raised position further removed from the object and which can be rapidly set for protecting the probes.

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Reutlingen, Germany

Heinrich Braun