Abstract: To determine the thickness profile of rolled metal sheets by measuring the absorption of X-rays a slit diaphragm is used which is rotatable about the imaginary center axis of the X-ray tube, the rotation consisting of a reciprocating movement lying in a range of less than 36.degree.. Between the reversal points of the rotation the rotational movement takes place in steps with rest intervals lying therebetween.

Abstract: A method and apparatus are provided for controlled grinding of roller surfaces. A rotary drive rotates a roller and a grinding wheel is rotated, which has a rotation axis parallel to the axis of the roller. The rotating grinding wheel is pressed against the rotating roller at a certain position along the axis of the roller. The grinding wheel is moved along the direction of its axis. Simultaneously, the surface of the roller is tested with an eddy current test probe disposed substantially at a corresponding position along the axis of the roller as the grinding wheel, however, the eddy current test probe is staggered with respect to the grinding wheel by a suitable angle around the roller axis. The signals from the eddy current test probe are processed by an analog-digital converter and then by a digital processor.

Abstract: An electrodynamic sound converter is disclosed for the non-destructive ultrasonic testing of workpieces during relative movement of the workpiece and the testing head. The testing head has an annular electromagnet which produces a magnetic field, and a rod-shaped core extends coaxially through the electromagnet and has a tip which projects beyond the same in direction towards the workpiece to be tested. The core is axially slidable relative to the electromagnet towards and away from the workpiece and the electromagnet and the tip of the core are each independently maintained at a fixed predetermined spacing from a surface of the workpiece being tested. The tip is being biased towards the surface, and a high-frequency coil is located adjacent the tip and serves to produce electromagnetic oscillations. Various modifications are also disclosed.

Abstract: An apparatus for non-destructively testing materials by ultrasound and eddy current, which includes an ultrasound material testing device operating in conformity with the electrodynamic converter principle, and also includes an eddy current material testing device. The testing coils of both testing devices are centrally arranged with regard to each other in such a way that the workpiece regions controlled by the testing coils have an at least approximately common central axis. The apparatus furthermore includes a control device which in conformity with the energization of the coil for creating the strong magnetic field for operation of the electrodynamic converter is operable briefly alternately respectively to turn-on and turn-off the respective testing coil of the ultrasound and eddy current material testing device.

Abstract: A method of and device for ultrasonically checking a workpiece while employing an electrodynamic sound converter including a checking head and a coil adapted to be energized to create a magnetic field, according to which during the checking operation the workpiece in a continuous movement relatively is passed by the testing or checking head of the electrodynamic sound converter. The coil for generating the magnetic field is energized by an alternating current or an intermittent or alternating direct current. Furthermore, the electrodynamic sound converter in conformity with the intensity of the magnetization of the coil is switched on and off in such a way that a sound converter is switched on when the magnetization has reached a predetermined value, and is switched off as soon as the magnetization drops below another predetermined value.

Abstract: An electrodynamic sound converter which comprises a magnet adapted to generate a magnetic field and direct same onto the surface of the workpiece to be checked by the electrodynamic sound converter, and which also includes an excitation coil located between the magnet and the workpiece to be checked for generating electromagnetic oscillations. That end of the magnet core of the magnet which faces the workpiece to be checked is so designed that the magnet core decreases in cross section toward its foremost point which is closest to the surface of the workpiece to be checked, the rate of increase increasing in the direction toward the foremost point of the magnet core.