Nukem Limited

Mannesmann Aktiengesellschaft

Klaus Abend

Gerhard Huschelrath

Heinz Schneider

Wolfgang Bottger

Ursula Orthen

Karl Laudenbach

An instrument for testing of test pieces made of paramagnetic or diamagnetic material as well as of ferromagnetic materials above their Curie point for material defects and/or dimensional accuracy, especially for testing of tubes and slabs above 1000.degree. C. The instrument comprises an electromagnetic transducer (EMT) having magnetic pole shoes and eddy current exciting and receiving windings; and an electronic signal processing unit. The inner pole shoe is conically tapered and fabricated from individual sheets parallel to one another and insulated from each other to prevent the formation of eddy currents that would give rise to undesirable ultrasonic waves that might interfere with the testing process. The pole shoes are positioned so as to develop a magnetic field parallel to the test piece, and the eddy current exciting and receiving windings are heat-insulated with respect to the test piece.

Instrument for testing materials

A method and an instrument for testing materials using the eddy current principle, at different frequencies depending on the output quantity of a coil system, compensation values are generated being typical of interfering factors. These compensation values are subsequently superposed on the output values in order to remove the influence of the interfering factors on the measuring. In this manner with a favorable setting of the working point of an amplifier charged with the output values, an overmodulation is avoided and the dynamic range of the amplifier optimally utilized. Therefore good measuring results can be obtained even if the percentage of the interfering signals as compared to the signal controlling the detecting of defects, is relatively high.

Eddy current test method with degree of amplification selected in

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Budingen, Germany

Klaus Abend