WO2000052459A1

WO2000052459A1 - Device and method for non-destructive material testing

Info

Publication number: WO2000052459A1
Application number: PCT/DE2000/000480
Authority: WO
Inventors: Dieter Pöpperl; Rainer Gebhardt; Kerstin Gemmer-Berkbilek
Original assignee: Siemens Aktiengesellschaft
Priority date: 1999-03-04
Filing date: 2000-02-21
Publication date: 2000-09-08
Also published as: DE19909528A1

Abstract

The invention relates to a device for the non-destructive material testing of a component (1), comprising a piezoelectric ultrasonic transducer (10-1) and an eddy-current probe (30). The eddy-current probe (30) is positioned in relation to the ultrasonic transducer (10-1) in such a way that when the ultrasonic transducer (10-1) is coupled to the component (1) it is situated between a side (14) of the ultrasonic transducer (10-1) which faces the component (1) and the component (1) itself. The eddy-current probe (30) can also be positioned on the side (35) of the ultrasonic transducer (10-1) which faces away from the component (1). The invention also relates to a method for the non-destructive material testing of a component (1) according to which ultrasound (12) is injected into the component (1) and an eddy current is generated in said component (1). The invention also provides for an eddy-current probe (30) to be penetrated by ultrasound (12) or for an ultrasonic transducer (10-1) to be penetrated by a magnetic alternating field which generates the eddy current.

Description

description

Device and method for non-destructive material testing

The invention is in the field of non-destructive measurement and testing technology.

The invention relates to a device for non-destructive material testing of a component, with

an ultrasound test head that can be acoustically coupled to the component, comprising an ultrasound transducer, and

- An eddy current probe for eddy current testing of the component.

In a first embodiment, the invention also relates to a method for non-destructive material testing of a component, in which ultrasound is coupled into the component and eddy current is generated in the component by means of an eddy current probe.

Furthermore, in a second embodiment, the invention relates to a method for non-destructive material testing of a component, in which the component is coupled in by means of an ultrasound transducer, and eddy current is generated in the component.

In the technical article “Non-destructive measurement of the effects of corrosion on high-temperature protective layers * by G. Dibelius, HJ Kπchel and U. Reimann, VGB Kraftwerkstechnik 70 (1990), pages 762 to 768, flat eddy current probes are described that are based on a flexible Carriers are applied so that the probe can follow the curvature at the measuring point.

A flexible coil for eddy current testing is known from EP 0 228 117 A2, which is attached to a flexible substrate. The coil is attached to versatile surface Customizable. For example, it can be produced photolithographically.

It is known to increase the reliability of the test statement in a non-destructive material test by combining an eddy current test with an ultrasonic test.

Corresponding test manipulators for eddy current and ultrasound testing are known for example from DE 196 41 888 AI and from German utility model DE 297 00 027.6 U. As a result of the combined use of two different test methods, these known test manipulators require a coupling or support surface that is large in comparison to an Emzel test head, in particular if an ultrasonic transducer used to decouple ultrasound and an eddy current probe used to generate eddy current are accommodated in a common test head or in a common housing and e.g. are also rigidly connected. For this reason, the manipulators disclosed in the cited documents are not suitable for testing on strongly curved surfaces. The known combined ultrasonic and eddy current test devices are also particularly voluminous compared to an Emzelprufemπchtung, so that they can not be used for testing difficult accessible test areas on the component or only with great effort.

From the German Offenlegungsschπften DE 26 52 085 AI and DE 35 30 525 AI devices for trouble-free material testing are known, in which an existing for generating ultrasonic waves electromagnetic ultrasonic transducer m connection with an eddy current measurement technology is used. These devices have one or more coils for ultrasound testing and also a separate coil which is provided for the purpose of eddy current testing and is arranged centrally within the coils present for ultrasound measurement. The electromagnetic working used Ultrasonic transducers (EMUS, or English: EMAT) are not sufficiently precise and reliable for numerous applications, especially in the field of nuclear technology.

The invention is therefore based on the object of specifying a device and a method for the non-destructive material testing of a component, with which even more difficult to access test areas can be checked very precisely, and which can also be used on more curved surfaces of the component.

This object is achieved with respect to the above-mentioned device according to the invention in that the ultrasonic transducer is designed as a piezoelectric transducer, and

- That the eddy current probe is arranged with respect to the ultrasonic transducer in such a way that when the ultrasonic transducer is coupled to the component it comes to rest at least partially between a side of the ultrasonic transducer facing the component and the component or at least partially on the side of the ultrasonic transducer facing away from the component.

The invention is based on the following unexpected results:

a) It is possible to insonify the ultrasound generated by a piezoelectric transducer through an eddy current probe into the component to be tested, and still enable a good acoustic coupling of the transducer to the component. b) Alternatively, it is possible to couple electromagnetic waves generated to induce the eddy currents in the component through a piezoelectric transducer into the component and to enable a sufficiently precise measurement despite the distance of the eddy current probe from the component which is predetermined by the thickness of the ultrasonic transducer. With the device according to the invention it is achieved, for example, that the ultrasound emitted by the ultrasound transducer is coupled into the component at the same point on the surface of the component to which the eddy current probe is coupled. In other words: the area of the acoustic coupling to the workpiece or component at least partially corresponds to an area of electromagnetic coupling to the component. As a result, the device can advantageously be constructed in a particularly space-saving manner.

The eddy current probe and the ultrasonic test head are accommodated, for example, in a common housing and in particular are rigidly connected to one another. There can also be several eddy current probes and / or ultrasonic probes.

The side facing the component and the side of the ultrasonic transducer facing away from the component are in particular the flat sides of the ultrasonic transducer.

In addition to the ultrasound transducer, the ultrasound test head includes, for example, a lead wedge and / or an adaptation layer.

According to a particularly preferred embodiment, the eddy current probe is arranged with respect to the ultrasound transducer in such a way that when the ultrasound transducer is coupled to the component it comes to lie at least partially between a coupling surface of the ultrasound probe and the component.

For example, the ultrasonic transducer is arranged on an upper wedge surface of the leading wedge. In this case, the lower wedge surface of the lead wedge is acoustically coupled to the component, ie it forms the coupling surface. The eddy current probe then lies between the lower wedge surface and the component. The eddy current probe can, however, also be arranged between the upper wedge surface of the lead wedge and the, in particular lower, side of the ultrasonic transducer facing the component.

The ultrasound transducer is, for example, a group emitter designed as an array.

The eddy current probe preferably comprises a probe coil arrangement.

The windings (“windings *) of a coil of the probe coil arrangement are arranged, for example, in one plane and / or have a spiral shape.

The probe coil arrangement is preferably a photolithographically produced arrangement of conductor tracks.

For example, the height of the conductor tracks is less than 0.1 mm or less than 0.02 mm.

The use of photolithography makes it possible to produce particularly thin conductor tracks. This is particularly advantageous if the eddy current probe is irradiated by the ultrasound. In this case, it is achieved by means of particularly thin conductor tracks that the ultrasound experiences only a slight disturbance when passing through the probe coil arrangement, in particular only a low absorption and reflection.

The probe coil arrangement comprises, for example, at least two coils.

According to another preferred embodiment, the eddy current probe has a film in or on which the probe coil arrangement is arranged. As a result, the space requirement of the device is further reduced. In particular, the film has a thickness of less than 0.5 mm or less than 0.02 mm.

In order to facilitate the coupling of the device to an uneven component surface, the film is preferably made of flexible material.

According to a very particularly preferred embodiment, the ultrasonic test heads, i.e. in particular the ultrasonic wand and the eddy current probe can be operated at different frequencies. This has the advantage that the ultrasonic test head and the eddy current probe do not influence one another, in particular when the distance is small and in particular when accommodated in a common housing.

The frequencies preferably differ from one another by at least a factor of 2. For example, the eddy current probe is operated at an eddy current frequency whose even multiples (harmonics) do not match a resonance frequency of the ultrasound transducer or an even multiple thereof.

According to another preferred embodiment, the ultrasonic test head and the eddy current probe can be operated alternately. Mutual influencing, for example by electromagnetic induction or mechanical vibrations, can also be reliably excluded by performing the ultrasound test and the eddy current test in such a timed manner in phase opposition.

The process-related object is achieved in relation to the first embodiment according to the invention mentioned at the outset in that the eddy current probe is at least partially exposed to ultrasound. In relation to the second embodiment, the object is achieved in that the ultrasound transducer is designed as a piezoelectric transducer and is at least partially penetrated by an alternating magnetic field that generates the eddy current.

The two methods can preferably be carried out with the device according to the invention. The advantages mentioned with regard to the device apply analogously to the methods.

In both embodiments, an eddy current frequency that is different from the ultrasound frequency is preferably set.

The ultrasound frequency and the eddy current frequency differ from one another by at least a factor of 2.

In an advantageous manner, ultrasound can alternately be coupled in and eddy current can be generated.

Three exemplary embodiments of a device according to the invention are explained in more detail with reference to FIGS. 1 to 6. The figures also serve to explain the method according to the invention. It shows:

1 shows a first embodiment of a device according to the invention in a longitudinal section (“vertical section *) along the line I-I of FIG. 2,

2 shows the device of FIG. 1 in a plan view of a section along the line II-II of FIG. 1,

3 shows a second embodiment of a device according to the invention in a longitudinal section, 4 shows a third embodiment of a device according to the invention in a longitudinal section (“vertical section *) along the line IV-IV of FIG. 5,

5 shows a plan view of the device of FIGS

6 shows a cross-sectional view through the device of FIG. 4 along the line VI-VI.

In the following description - without restricting the generality of the statements made therein - it is assumed in the usual way for ultrasonic testing technology that the ultrasonic test head is “coupled” to the component to be tested and thereby lies above it. In this sense, the terms "horizontal * and" vertical * are used below.

FIG. 1 shows in a vertical section a component 1 which is subjected to a non-destructive material test. For this purpose, an ultrasonic test head 10 is acoustically coupled to the surface 2 of the component 1, which includes an ultrasonic transducer 10-1 for coupling ultrasound 12 into the component 1. The ultrasonic transducer 10-1 has a smooth cut, plane-parallel piezoelectric body and electrodes (not explicitly shown).

The side 14 of the ultrasonic transducer 10-1 facing the component 1 forms a coupling surface 10-2 with which the ultrasonic test probe 10 is coupled to the component 1 — indirectly in the example shown. An eddy current probe 30 is arranged between the coupling surface 10-2 and the surface 2 of the component 1. This consists among other things of a film 30-1 made of temperature-resistant and flexible material M and with a thickness D of less than 0.1 mm. The material M is, for example, polyamide. A probe coil arrangement 30-2 is arranged on the film 30-1 and is designed as a photolithographically produced conductor track 30-3 with a height H of less than 0.1 mm.

The height H of the conductor track 30-3 is drawn in a greatly exaggerated manner in FIG. 1 for better illustration.

The ultrasound 12 generated by the ultrasound transducer 10-1 penetrates the eddy current probe 30 below it before it penetrates into the component 1. The area of the surface 2 of the component 1 located under the ultrasonic transducer 10-1 serves both as an acoustic coupling surface and also for the penetration of an electromagnetic field (not shown) generated by the eddy current probe 30, which leads to the generation of the desired eddy current in the component 1.

Figure 2 shows the device of Figure 1 in a plan view with the ultrasonic transducer 10-1 removed (section along the line II-II). It can be seen from this that the conductor track 30-3 of the probe coil arrangement 30-2 forms a spiral or helical and planar coil. The conductor track 30-3 is contacted with a contact wire 33 at a first coil end 30-4 located at the edge of the film 30-1. It winds with a decreasing radius from turn to turn to a second coil end 30-5 located approximately in the middle of the film 30-1, from which a further contact wire 32 extends, which goes up through a bore 10-3 (see FIG. 1 ) is supplied to a control unit that is not explicitly shown.

In the second exemplary embodiment of a device according to the invention shown in FIG. 3, in contrast to the exemplary embodiment shown in FIG. 1, the eddy current probe 30 is arranged on a side 35 facing away from component 1, ie on the upper side, of the ultrasonic transducer 10-1. In the device of the second embodiment, follows the electromagnetic coupling of the eddy current probe 30 to the component 1 through the ultrasonic transducer 10-1. This means that the largest proportion of the magnetic field lines generated by the probe coil arrangement 30-2 penetrates the ultrasonic probe 10.

The ultrasound transducers 10 of FIGS. 1 to 3 are prepared for vertical insonification in pulse-echo operation.

FIG. 4 shows a further exemplary embodiment in which the ultrasound test head 10 and the eddy current probe 30 are arranged in a common housing 10-4 and are firmly connected to one another therein. The ultrasonic transducer 10-1 is enclosed on the side 35 facing away from the component 1 by a damping body 10-5 made of cork. With the side 14 facing the component, the ultrasound transducer 10-1 is coupled via a matching layer 10-6 (λ / 4 layer) to a leading wedge 10-7 made of plexiglass and penetrated by the coupled ultrasound 12.

FIGS. 5 and 6 show the device shown in FIG. 4 in a vertical section in a plan view of the ultrasonic test head (FIG. 5) with the housing 10-4 unlocked and the damping body 10-5 removed or in a horizontal section (FIG. 6) along the Line VI-VI of the

Figure 4. It can be seen from Figure 5 that the leading wedge 10-7 is divided into two wedges by an acoustic separating layer 10-8 made of cork. The ultrasound transducer 10-1 is also designed in several parts in this embodiment. It consists of an ultrasonic transmitter 10-1T, which is acoustically coupled to one of the partial wedges, and an ultrasonic receiver 10-1R, which is acoustically coupled to the other partial wedge. Due to this configuration of the leading wedge 10-7 and the ultrasonic transducer 10-1, the illustrated ultrasonic probe 10 is particularly suitable for a transmit / receive operation. FIG. 6 shows that the probe coil arrangement 30-2 in the third exemplary embodiment comprises a first coil 30-2A and a second coil 30-2B, which can be operated, for example, in a differential circuit (not shown). When the ultrasonic transmitter 10-1T is coupled to the component 1, the first coil 30-2A comes to lie between the latter and the component 1. In an equivalent manner, the second coil 30-2B then lies under the ultrasound receiver 10-1R. The conductor tracks 30-3 of the largely planar probe coil arrangement 30-2 of the eddy current probe 30 are contacted via contact wires 32, 33, 44, 45. The contact wires 32, 44, which originate from the coil ends not located at the edge of the film 30-1, are guided via horizontally running grooves 10-9, 10-10 to the vertical bore 10-3, which passes through the separating layer 10-8 runs above, and through which these contact wires 32, 44 are guided to the outside. The grooves 10-9, 10-10 are milled on the underside of the leading wedge 10-7.

The turns of the coils 30-2A, 30-2B are essentially rectangular in shape with the width and length of the rectangle decreasing from turn to turn.

In FIG. 4, the conductor tracks 30-3 of the probe coil arrangement 30-2 — in contrast to FIGS. 1 and 3 — are not shown at an excessive height, so that they cannot be seen there. The probe coil arrangement 30-2 is arranged between the film 30-1 and the lead wedge 10-7. In order to protect the film 30-1 from abrasion and dirt, it is covered with a protective layer 30-6 which lies directly on the surface 2 of the component 1.

Instead of between the component 1 and the leading wedge 10-7, the eddy current probe 30, in particular the film 30-1 with the probe coil arrangement 30-2, could also be arranged between the ultrasonic transducer 10-1 and the leading wedge 10-7. It could also be attached to the side 35 of the ultrasonic transducer 10-1 facing away from the component 1. The ultrasonic transducer 10-1 is operated at an ultrasonic frequency in the range from 1 MHz to 15 MHz, for example at 2 MHz. The eddy current probe 30 is electrically excited with an eddy current frequency from the interval of 50 kHz and 900 kHz, for example 600 kHz.

Instead of the two coils 30-2A, 30-2B, three or more coils can be provided in any arrangement.

Claims

claims

1. Device for non-destructive material testing of a component (1), with - an ultrasonic test head (10) that can be acoustically coupled to the component (1), comprising an ultrasonic transducer (10-1), and - an eddy current probe (30) for eddy current testing of the component (1 ), characterized in that the ultrasound transducer (10-1) is designed as a piezoelectric transducer, and that the eddy current probe (30) is arranged with respect to the ultrasound transducer (10-1) in such a way that when the ultrasound transducer (10 -1) at least partially between a side (14) of the ultrasonic transducer (10-1) facing the component (1) and the component (1) or at least partially on the side (35) of the ultrasonic transducer (10-) facing away from the component (1) 1) comes to rest.

2. Apparatus according to claim 1, characterized in that the eddy current probe (30) is arranged with respect to the ultrasonic transducer (10-1) such that it is at least partially between a coupling surface when the ultrasonic transducer (10-1) is coupled to the component (1) (10-2) of the ultrasonic test head (10) and the component (1) comes to rest.

3. Apparatus according to claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t that the eddy current probe (30) comprises a probe coil arrangement (30-2).

4. The device according to claim 3, characterized in that the probe coil arrangement (30-2) is a photolithographically produced arrangement of conductor tracks (30-3).

5. Apparatus according to claim 4, d a d u r c h g e k e n n z e i c h n e t that the height (H) of the conductor tracks (30-3) is less than 0.1 mm.

6. Device according to one of claims 3 to 5, so that the probe coil arrangement (30-2) comprises at least 2 coils.

7. Device according to one of claims 3 to 6, that the eddy current probe (30) has a film (30-1) in or on which the probe coil arrangement (30-2) is arranged.

8. The device according to claim 7, d a d u r c h g e k e n n z e i c h n e t that the film (30-1) has a thickness (D) of less than 0.5 mm.

9. Apparatus according to claim 7 or 8, d a d u r c h g e k e n n z e i c h n e t that the film (30-1) consists of flexible material (M).

10. Device according to one of claims 1 to 9, so that the ultrasonic test head (10) and the eddy current probe (30) can be operated at different frequencies.

11. The device as claimed in claim 10, so that the frequencies differ from one another by at least a factor of two.

12. Device according to one of claims 1 to 11, characterized in that the ultrasonic test head (10) and the eddy current probe (30) can be operated alternately.

13. A method for non-destructive material testing of a component (1), in which ultrasound (12) is coupled into the component (1) and an eddy current probe (30) is used to generate eddy current in the component (1), characterized in that the eddy current probe (30) at least is partially transmitted through the ultrasound (12).

14. Method for non-destructive material testing of a component (1), in which an ultrasonic transducer (10-

1) Ultrasound (12) is coupled into the component (1) and eddy current is generated in the component (1), characterized in that the ultrasound transducer (10-1) is designed as a piezoelectric transducer and at least partially from an alternating magnetic field generating the eddy current is penetrated.

15. The method according to claim 13 or 14, d a d u r c h g e k e n n z e i c h n e t that an eddy current frequency different from the ultrasonic frequency is set.

16. The method according to claim 15, so that the ultrasonic frequency and the eddy current frequency differ from one another by at least a factor of 2.

17. The method according to any one of claims 13 to 16, d a d u r c h g e k e n n z e i c h n e t that alternately coupled ultrasound (12) and eddy current is generated.