Institut Dr. Friedrich Forster, Prufgeratebau

Institut Dr. Friedrich Forster Prufgeratebau Gmbh & Co Kg

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Peter Haberlein

Ulrich Dreher

A method and apparatus for testing an elongate product for faults and defects, which comprises a rotatable testing head which permits the elongate product to be passed coaxially therethrough and which mounts a pair of testing probes so as to permit adjustment of their operating diameter. In order to automatically adjust the positions of the probes to accommodate elongate products of different sizes, there is provided an external adjustment unit, which stops the testing head in a predetermined angular position. The adjustment unit contains an external adjustment drive and when the rotation of the testing head has stopped, the external adjustment drive is advanced into operative engagement with the adjustable mounting of the testing probes. A measuring pin is also advanced into contact with the mounting of the testing probes so as to monitor the exact position of the probes, and during the repositioning of the probes a signal from the measuring pin is fed back to a control device to assure the precise positioning of the probes.

Method and apparatus for adjusting the operating diameter of a probe in

The described rotating head effects A.C. field stray flux defect testing process using a rotating magnet yoke for high magnetizing field strength. The unit is compact and replaces a great number of conventional stationary devices in which the test article must be moved along a helical line past the magnet yoke. A speed of the rotating head of 900 revolutions per minute with an effective width of the probe support of 10 cm, achieves a testing speed of approximately 1.5 m/sec. This high testing speed makes the use of A.C. field stray flux testing at high magnetizing field strength possible from the economical point of view.

Magnet and probe mounting means on a rotating head of magnetic defect

A representative reading for the concentration of a suspension of luminous and magnetizable particles is provided in every case, even when luminous but non-magnetizable particles are also present. That is, the presence of non-magnetizable luminous particles in the suspension have no effect on the determination. A rotating wheel-like member has its lowermost portions immersed in a supply of the magnetic particle suspension in a fluid carrier. The circumferential periphery includes a permanent magnet having a gap extending continuously around the periphery and covered over by a plastic rim. As the wheel-like member rotates, the magnetic particle suspension forms a bead along the magnet gap. Ultra violet radiation directed onto the bead causes the magnetic particles to fluoresce and the degree of fluorescence is measured by photosensitive means.

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Reutlingen, Germany

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