Abstract: The invention relates to an ultrasonic measuring unit for attaching to a measuring instrument. The measuring instrument is designed in such a way that the measuring instrument can be arranged on a movement axis of a machine. When the ultrasonic measuring unit is arranged on the measuring instrument, an ultrasonic measurement can be carried out by means of the ultrasonic measuring unit. The ultrasonic measuring unit comprises a tubular sleeve and an elastic carrier element. The tubular sleeve surrounds the elastic carrier element. The elastic carrier element consists of a material that conducts ultrasonic waves. At a first end of the tubular sleeve, the elastic carrier element protrudes beyond an outer edge of the tubular sleeve. The tubular sleeve and the elastic carrier element are intended to contact, in particular directly, the surface to be measured, during a probing process of the measuring instrument.

Abstract: The invention relates to a method and means for measuring the depth of cracks, using a potential probe connected to a measuring instrument and having two current terminals and additional voltage-measuring terminals (potential probe method).The object of the invention is to eliminate the separate calibration devices needed for the checks and collective measurements necessary when using known potential probes, and to make the check measurements in conjunction with the actual depth-measuring process.This problem is solvable by using a potential probe (S) as per the drawing, where at least two pairs of terminals (1+2, 3+4) having known but different spacings serve as adjustment measuring portions and are connected to an adjustment circuit (JM, UM) in a measuring-instrument microcomputer (M) and an additional pair of terminals (2, 3) having a known spacing serve as a crack-depth measuring portion and are connected to a crack-depth measuring circuit (TM) in the microcomputer.

Abstract: A method of and apparatus for measuring the layer of coating thickness of non-magnetic substances on a ferromagnetic parent material by the magneto-inductive method or of non-metallic substances on a conductive parent material by the eddy current method. This is done with the use of a probe whose coil inductance is evaluated as a criterion for the thickness of the layer to be measured. An adjustment to the geometry and the magnetic properties of the specimen are made before the first measurement. In the adjustment, at least one non-magnetic or non-conductive foil is disposed or are consecutively disposed between the probe and the surface of the coated specimen and the measured data obtained then and in the subsequent measurements are fed to a microcomputer.

Abstract: A method of measuring the thickness of test articles by pulse reflection ultrasonics, the length of time period as determined by the signal triggering the ultrasonic transmission and by an ultrasonic signal reflected at the end of the measurement path length being used to determine the distance travelled by the ultrasonics. In the method, the triggering signal for the ultrasonic transmitter is generated in phase with a measuring oscillation of a high and known frequency, whereafter the integral number of measuring oscillation pulses or waves which fit into a time period corresponding to measurement path length are counted, whereafter the measuring oscillation is so detuned that the residual measuring oscillation or wave found over and above that in the time period is reduced to zero and a correction value is derived from the amount of frequency detuning for the measurement path length resulting from the integral number of measuring oscillation pulses or waves.

Abstract: A method and device for the automatic detection and evaluation of optical crack indication on the surface of workpieces is disclosed. In such method and device, visual displays are converted into electrical bright-dark signals by the use of light sensitive device, for example, an image recording tube. The surface under observation is scanned by the light-sensitive device line by line, the width of each of which (either as individual line or groups of adjacent lines) corresponds to the maximum optical display width from which evaluation is to proceed. The bright-dark signals thus obtained from three lines or lines groups are compared. From the signal of the middle line or line group and the signals of the two other line or line groups there is formed a difference signal which is evaluated to generate an error evaluation signal of a minimum value is exceeded.