Institut Dr. Friedrich Forster, Prufgeratebau

Institut Dr. Friedrich Forster

Ulrich Dreher

Hans Link

Helmut Reitz

A driver for oblong material having three arms carrying the driving elements which swing vertically with respect to the material path of movement. For a selected setting angle of the arms, the point of contact of a driving roller with the material is displaced such that, on the diameter of the test material becoming smaller, the point of contact is moved towards the edge of the roller. This feature has three desirable consequences: First, wear is not concentrated on a single track of the roller surface; second, the pressing-on force of the rollers is decreased with the decreasing diameter of the test material; and third, when using three rollers, the seeing angle can be adjusted such that for the narrowest approach of the rollers possible, one edge each of a roller meets with the respective edges of the other rollers in one point.

Self-centering driver for oblong material

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.

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Trochtelfingen, Germany

Ulrich Dreher