Nukem Limited

Mannesmann Aktiengesellschaft

Gerhard Huschelrath

Ewald Kowol

Klaus Abend

Herbert Diehl

Ursula Orthen

Karl Laudenbach

Heinz Schneider

Wolfgang Bottger

Roman Koch

Ursula Ruth

Ekkehard Behl

Wilfried Lein

An electrodynamic transducer head which has at least two detachably arranged probes are allocated to one pole shoe of a magnet, and are covered by a common protective plate. The transducer head can be used for non-destructive testing of workpieces using ultrasound, for which purpose a cap of the transducer head has sliding blocks which rest on the workpiece.

Electrodynamic transducer head

The subject of the invention is a device for non-destructive testing of long bodies (14) for structural faults by means of magnetizing the respective body (14). At least one magnetic field is directed onto the body (14). The structural faults in the body cause changes in the magnetic field pattern. The changes are picked up by magnetic field sensors (50, 52) arranged on or near the body surface. The respective body (14) is moved through the magnetic field, which has an inclination of preferably 45.degree. to the transportation direction (26) of the body (14). The magnetic field sensors (50, 52) are oriented transverse to the direction of the magnetic field.

Device having electromagnet for providing a magnetic field inclined with

The object of the invention is a method and a device for materials testing using the eddy-current principle. If a coil (30) is moved in relation to test specimens, magnetic alternating fields with differing frequencies are generated, these fields induce eddy-currents that cause a secondary field in the coil (30). A number of test specimens having the same structure and the same dimensions are measured. The measured values are stored. The coordinates of the center of gravity of the measured values in the complex plane are then determined. The the phase angle is determined of that axis which runs longitudinally through the field (20) formed by the measured values in the complex plane. The center of gravity is then rotated into the origin of the coordinate system and the axis into a coordinate axis. Then a threshold value envelope determining a fault boundary is placed around the field of the measured values. The threshold value curve is then displaced by the coordinates of the center of gravity and rotated by the phase angle of the axis. In later measurement of test specimens for fault detection, the measured values are directly compared with the values of the transformed threshold value envelope.

Method and device for testing for flaws with the eddy-current principle

A method and a device for non-destructive testing of ferro-magnetic bodies for structural faults by means of magnetization. The structural faults cause changes in the magnetic field which are picked up by stationary magnetic field detectors arranged close to the surface of the body, which are arranged perpendicular to the direction of magnetization of the body. The outputs of the magnetic field detectors are connected in a time-division multiplex manner to an evaluation unit. Predetermined positions of the magnetic field detectors are assigned compensation values in relation to the position of the respective weld, the compensation values being subtracted with the correct sign from the measured values produced by the magnetic field detectors. The corrected measured values obtained in this manner are subjected to a threshold value test to determine if structural faults are present. Furthermore, a lateral deviation of the weld from its original position is monitored. The compensation values are reassigned in accordance with the actual position of the weld with regard to the magnetic field detectors before the values are offset once more against the measured values.

Method and apparatus to compensate for lateral changes of a

This invention provides for the non-destructive testing of a longitudinally displaceable ferromagnetic body for structural faults. This device sends a stationary magnetic field transversely across the body of the test piece. Changes in this magnetic field, due to structural defects of the test piece, are detected by the magnetic field detectors which are placed on the periphery of the test piece in alignment with the stationary magnetic field. The changes detected by the magnetic field detectors must be processed in order to be useful. This processing requires compensation for the varying strength of the magnetic field at the surface of each different magnetic field detector, compensation for unequal sensitivities of each individual magnetic field detector in detecting structural defects, and also compensating for the tolerances of circuits which are used in the previous compensations.

Device for the non-destructive testing of ferromagnetic bodies and a

The subject of the invention is a method and a device for non-destructive testing of ferromagnetic bodies (1) for structural faults. The bodies (1) are magnetized. Structural faults cause changes in the magnetic field pattern which are measured with magnetic field detectors (6). Surface waves are generated electro-dynamically utilizing the magnetic field generated for magnetizing the body (1). Those structural faults extending up to the surface can be detected with the surface waves. To distinguish between the structural faults extending to the surface of the body at one point and those structural faults inside the body (1), it is determined whether the measured values gained both from the leakage flux and from the surface waves indicate structural faults or whether only the measured values gained from the leakage flux indicate structural faults.

Method and device for magnetic and ultrasonic testing of ferro-magnetic

The object of the invention is a device with two Hall generators (12, 14) for measuring the gradients of magnetic leakage fields in the non-destructive testing of materials. The two Hall generators (12, 14) are arranged at a distance from each other with their broad sides on a flat carrier substrate (18). They are positioned along a common line (36) with respect to which they each have the same alignment. Furthermore the two Hall generators are arranged close to the edges (40) of two opposite sides of the carrier substrate (18) that are free of connections.

Device with two generators for measuring the gradients of magnetic fields

The subject of the invention is a method and device for non-destructive testing of electrically conducting objects (10) by means of penetrating ultra-sonic waves, whereby the ultra-sonics signals are electro-dynamically generated. While being tested the object is located in a magnetic field. The probes (30, 32) arranged on diametrically opposite sides of the object (10) are set at the smallest possible constantly maintained distance from the surface. The signals used for detecting the flaw are corrected so that any variations in the thickness of the object (10) in the area of the probes (30, 32) are taken into account.

Method and device for testing electrically conducting objects by means

An electrodynamic transducer (10) is disclosed for non-destructive material testing comprising at least one internal pole shoe (16) of an electromagnet with core (12) and magnetic winding (14). The end section (18) of the internal pole shoe (16) is arranged eccentrically in relation to the center axis (29) of the core (12) and is designed to rotate with the core (12) about the center axis (29) thereof.

Electrodynamic transducer

The invention relates to a method and a device for measuring the wall thickness of bodies by means of ultrasonic pulses. The ultrasonic pulses are created in the bodies and reflected on the walls. The transit times of the ultrasonic pulses reflected on the walls are measured. The wall thickness is determined from the transit times by considering the respective sonic speed in the body. The measured signals obtained with a receiver are each compared with a threshold value that is set to a low base value (17a) at the beginning of the measurement. With each measured signal exceeding the associated threshold value (17a, 17b, 17c, 17d respectively) the threshold value is reset to the amplitude of the measured signal. The times from a specified starting time are measured up to the measured pulses that exceed the threshold values. The maximum value of the time corresponds to the transit time of the back wall echo (13).

Method for measuring the wall thicknesses of bodies by means of

A method and an apparatus for testing materials using the eddy current principle enables a better exploitation of the sensitivity of measurement. Initially, the complex values appearing during a test cycle are examined as to whether only disturbance signals, disturbance signals in connection with flaw signals, or only flaw signals are present. The complex values are selectively further processed directly if there are flaw signals only, or are further processed for disturbance signal elimination. The direct further processing as well as the further processing made after elimination of the disturbance signal comprises the determination of the type of flaw and the depth of the flaw.

Method and apparatus for separating magnetic field attributable to flaws

An electrodynamic transducer head for the non-destructive ultrasonic testing of workpieces (12) comprises an electromagnet having a magnet yoke with an external pole shoe and an internal pole shoe (10, 14) surrounded by the external pole shoe. Exciting and receiving coils (16, 18) are arranged on these pole shoes. To enable the internal pole shoe (10, 14) to be placed directly on the workpiece (12) moving relative thereto without danger, these pole shoes are provided with a protective cap (20) surrounded by a protective ring (22), the end face of the protective ring (22) turned towards the workpiece (12) projecting beyond that of the protective cap.

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

An apparatus for non-destructively testing ferromagnetic bodies to determine structural irregularities by means of magnetization of the respective object, comprises detectors for magnetic fields arranged close to the surface of the body, by which detectors any changes of behaviour of the magnetic field caused by structural irregularities can be determined. At least two stationary magnetic fields are arranged one after the other on the body that can be displaced in its longitudinal direction, the center axes of these magnetic fields being inclined toward each other at an angle. This angle is determined by the number of magnetic fields and is equal to the quotient from one hundred and eighty degrees and the number of magnetic fields. In the space between the poles of the magnetic field generators, the magnetic field detectors are stationarily arranged and in rows, each extending over a zone being equal to a body section to be tested, vertically to the shifting direction of the body. The outputs of the magnetic field detectors are connected time-multiplex to an evaluation circuit.

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Laufach-Frohnhofen, Germany

Gerhard Huschelrath