INSPECTION DEVICE FOR THE INSPECTION OF TWO-DIMENSIONALLY EXTENDING METAL OBJECTS

Abstract

An inspection device is provided for inspecting metallic objects extending in planar fashion, in particular sheets or walls. The inspection device is embodied as pipeline-impassable in particular by virtue of dispensing with at least one propulsion element that at least substantially fills an inner pipeline cross section. At least one functional unit is included for recording object information. At least one magnet unit is provided for magnetizing the object, the magnet unit including a plurality of magnets. The magnet unit has a plurality of segments each having at least one magnet, and the magnetization directions of segments adjoining one another are angled at least approximately by 90°, preferably by exactly 90°, relative to one another.

Claims

1. An inspection device for inspecting metallic objects extending in planar fashion, the inspection device being embodied as pipeline-impassable, the inspection device comprising: at least one functional unit for recording object information; at least one magnet unit provided for magnetizing the object and having a plurality of magnets, wherein the magnet unit has a plurality of segments each having at least one magnet and wherein magnetization directions of segments adjoining one another are angled at least approximately by 90°, relative to one another.

2. The inspection device as claimed in claim 1, wherein the magnet unit has magnets embodied as permanent magnets, wherein the poles (N, S) directed toward one another of two segments separated by a further segment have an identical polarity.

3. The inspection device as claimed in claim 2, wherein the segment arranged between the two segments as a vertical segment has, during operation, a magnetization direction which is directed in the direction of a surface of the object to be inspected.

4. The inspection device as claimed in claim 3, wherein the vertical segment is bounded by a focusing element toward the surface of the object to be inspected.

5. The inspection device as claimed in claim 4, wherein the focusing element is bounded by a magnet on at least three sides, the poles of the magnets that are situated on these sides having an identical polarity.

6. The inspection device as claimed in claim 1, wherein the magnet unit is positioned in a longitudinal direction parallel to the surface of the object to be inspected, and has at least one surround which is at least concomitantly formed from a magnetizable material and which bounds the magnets of the magnet unit.

7. The inspection device as claimed in claim 4, wherein the magnet unit has a sensor for recording inspection data.

8. The inspection device as claimed in claim 7, wherein the sensor is arranged in the focusing element, in a recess thereof and/or on the focusing element.

9. The inspection device as claimed in claim 1, wherein the magnet unit, in the longitudinal direction thereof, has at least three magnets arranged one behind another.

10. The inspection device as claimed in claim 1, wherein a plurality of magnet units are arranged next to one another.

11. The inspection device as claimed in claim 1, further including at least one in particular adjustable spacer which allows the magnet unit to be positionable at a distance from the surface of the object.

12. The inspection device of claim 1, wherein the inspection device is pipeline-impassable due to a lack of a propulsion element that at least substantially fills an inner pipeline cross section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Reference is now made more particularly to the drawings, which illustrate the best presently known mode of carrying out the invention and wherein similar reference char-acters indicate the same parts throughout the views.

[0026] FIG. 1 shows a spacer with a magnet unit of a device according to the invention in a perspective illustration.

[0027] FIG. 2 shows the device according to FIG. 1 in a partly cut-away view.

[0028] FIG. 3 shows a perspective illustration of a further magnet unit with sensors.

[0029] FIG. 4 shows a basic illustration of the use of an inspection device according to the invention.

[0030] FIG. 5 shows a simplified view of a magnet unit of a further device according to the invention in a partly sectional illustration.

[0031] FIG. 6 shows a magnet unit of a further inspection device according to the invention.

[0032] FIG. 7 shows a view of a magnet unit of a further object according to the invention in a sectional illustration and a perspective illustration.

[0033] FIG. 8 shows magnetic field lines in a magnet unit of an inspection device according to the invention and also an object to be inspected.

[0034] FIG. 9 shows a magnet unit of a further object according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0035] Individual technical features of the exemplary embodiments described below can also be combined in combination with exemplary embodiments described above and also the features of the independent claim and any further claims to form subjects according to the invention. In so far as is expedient, elements having an identical functional effect are provided with identical reference numerals.

[0036] FIG. 1 shows a perspective illustration of a part of a spacer 1 of an inspection device according to the invention, said spacer having a magnet unit 3. The spacer 1 comprises a housing 2, in which the magnet unit 3 is housed, said magnet unit being discernible in FIG. 3. The housing 2 is depicted such that its side directed toward the surface of the object to be inspected is illustrated facing upward in FIG. 1. A distance with respect to the object is adjusted by way of a wheel 4 mounted rotatably in a fork 6. Two sensors respectively embodied as transmitting and receiving transducers serve for generating and recording measurement signals. Illustrated at the opposite end of the spacer 1 is a further fork 8, which can be mounted on a supporting frame of an inspection device according to the invention and/or can optionally be provided with a further wheel.

[0037] The magnet unit 3 has two magnets 10, whose magnetization directions (direction north-south) run parallel or at least approximately parallel to the longitudinal direction F, corresponding to the main movement direction of the inspection device during operation, and whose north pole sides 12 face toward one another (FIG. 2). Relative to the magnet unit 3, in FIG. 2 the direction arrow is situated on the side of the surface to be inspected during operation.

[0038] At the same time, both north pole sides 12 bear against a focusing element 14. On its side situated toward the direction arrow F, a further magnet 18 goes against said focusing element with its north pole side 16 (cf. FIG. 3). This magnet has a magnetization direction which is tilted or angled by 90° with respect to the magnetization direction of the magnets 10.

[0039] In the longitudinal direction of the magnet unit running parallel to the arrow F, the magnet unit has surrounds 20 constructed from a magnetizable material, preferably a steel comprising cobalt and iron, the surrounds 20 bounding the magnets of the magnet unit 3 in such a way that they adjoin the latter at the front and back in the longitudinal direction.

[0040] The focusing element 14 is also composed of a steel comprising cobalt and iron. By virtue of the arrangement outward away from an underside 15 and in the direction toward the surface of the object to be inspected, the focusing element 14 attains flux densities of preferably 2 to 3 teslas. The magnetic flux is compressed by the magnet 18 by means of the focusing element 14 embodied as a steel element in such a way as to result in focusing of the magnetic field lines toward the object. While standard Halbach arrays are limited in terms of their maximum introduction of the magnetic field by the saturation flux density, the embodiment of the inspection device according to the invention increases the attractive force by up to a factor of at least 3 as described above. Therefore, weight and costs can be kept correspondingly low. In the exemplary embodiments in the figures, the segments of the magnet units are each formed by a magnet, which then also predefines the magnetization direction of the respective segment.

[0041] On one side of the magnet unit 3 there is an inner surround 22, which additionally shields the magnetic field of the magnet unit 3, said magnetic field already being virtually negligible anyway, in this direction.

[0042] The magnet unit according to FIG. 1 is supplementarily illustrated in FIG. 3. Such a magnet unit together with the sensors 5 forms a part of a functional unit for recording object information in the form of sensor data.

[0043] An inspection device according to the invention in accordance with FIG. 4 is provided with a handle 27, which constitutes the upper end of a guide device having a guide rod 29, by means of which guide device the inspection device can be moved by an operator 31 in the direction F along a surface of an object 32 to be inspected in the form of a metal sheet. This involves for example a lower boundary or wall of an oil store.

[0044] The functional unit of the inspection device furthermore comprises the sensors 5 and, in the further housing 33, means for signal generation and evaluation. The sensors 5 are in particular EMAT-WT sensors, i.e. sensors for the electromagnetic-acoustic measurement of the wall thicknesses of the object 32.

[0045] A magnet unit 3 of a further inspection device according to the invention having a greater number than three magnets is illustrated in FIG. 5. In the present case, focusing elements 14 are each arranged on the north pole sides of the adjacent magnets 10 and 18, respectively. A further focusing element 14′ is correspondingly bounded by south pole sides of the adjacent magnets. In addition to this, a magnet unit can have the surround 20 illustrated in FIG. 6, as already described.

[0046] FIG. 7 discloses, in the two depictions there, an alternative embodiment of a magnet unit 3. The depiction at the top right in FIG. 7 shows a perspective illustration, while a matching cross section is illustrated at the bottom left in FIG. 7. A hemispherical focusing element 14 is bounded by an integral or multipartite magnet 10, which is annular in cross section and which is in turn arranged within a surround 20. The surround 20 composed of steel in the form of a hemispherical shell serves as a magnetic return path.

[0047] The magnetic field lines that arise in a magnet unit 3 and the object 32 arranged closely beside the latter during operation are symbolized by black acute triangles in FIG. 8. A sensor 5 is present in this case, but not illustrated. In FIG. 8, the triangles are situated in the cells of a triangular grid—produced on the basis of the computational simulation of the magnetic field lines—both of the magnet unit 3 and of the wall of the object 32. The greater the gradients of the magnetic field lines in relation to direction and/or amplitude, the finer the resolution and the smaller the cells of the grid. The magnetic flux densities present in the focusing elements 14, 14′ are particularly high, symbolized by correspondingly large triangles.

[0048] A magnet unit which is particularly well suited to the use of an inspection device embodied as an autonomous handheld inspection apparatus additionally has magnets on the sides which furthermore focus the magnetic field on the focusing element 14 and intensify it in the manner described above.