WO2017174391A1

WO2017174391A1 - Ultrasonic probe and ultrasonic inspection system

Info

Publication number: WO2017174391A1
Application number: PCT/EP2017/057227
Authority: WO
Inventors: Michael Schmeisser; Michael Kronenbitter
Original assignee: Institut Dr. Foerster Gmbh & Co. Kg
Priority date: 2016-04-04
Filing date: 2017-03-27
Publication date: 2017-10-12
Also published as: EP3440458A1; RU2018136368A3; JP7122973B2; KR102339444B1; RU2732102C2; CN109196349A; DE102016205548A1; KR20180128053A; JP2019516093A; RU2018136368A

Abstract

The invention relates to a probe (100) for an ultrasonic inspection system for nondestructive material inspection during movement of a test object relative to the probe in an inspection direction, comprising a probe housing (110), which defines a longitudinal direction (L) in the inspection direction and a transverse direction (Q) perpendicular to the inspection direction, and a plurality of transmitting-receiving units (150-1, 150-2, 150-3). Each transmitting-receiving unit has a transmitter element (T1, T2, T3) and an associated receiver element (R1, R2, R3) and defines an effective inspection width (PB1, PB2, PB3) in the transverse direction (Q) in such a way that, during movement of the test object relative to the probe in the inspection direction, an inspection track having the effective inspection width can be inspected by means of the transmitting-receiving unit. The transmitting-receiving units are arranged in at least two rows (155-1, 155-2) which are consecutive in the longitudinal direction (L) and extend in the transverse direction (Q). Transmitting-receiving units from different rows are mutually offset in the transverse direction (Q) in such a way that receiver elements (R1, R2, R3) of mutually offset transmitting-receiving units overlap each other in an overlapping region (U1-2, U2-3) such that the totality of the transmitting-receiving units continuously covers an effective probe inspection width (PKPB). All the transmitting-receiving units are mounted in the probe housing (110). All the transmitter elements (T1, T2, T3) are electrically connected to a common transmitter connection element (AT) of the probe.

Description

Ultrasonic testing head and ultrasonic testing system

Field of application and state of the art

The invention relates to a test head for an ultrasonic testing system for non-destructive material testing with relative movement of a test object relative to the test head along a test direction.

The ultrasonic test is an acoustic method for finding material defects, so-called discontinuities, as well as for determining component dimensions by means of ultrasound. It belongs to the nondestructive testing methods. In non-destructive material testing with ultrasound (US) the sound is transmitted via a coupling medium, eg. B. a liquid layer, transferred from the probe to the DUT. The transmission of the ultrasound waves carrying the information about the state of the test specimen from the test specimen to the receiving test head generally also takes place via the same coupling medium. For transmitting and receiving the ultrasonic waves or the ultrasonic pulses separate transmit and Empfangsprüfköpfe can be used. Test head is here understood to mean the handling unit in which one or more ultrasonic transducers are installed. The ultrasonic transducer itself is the element that converts the electrical signal into a sound signal (acoustic signal) or a sound signal into an electrical signal. Most of the sound-emitting and sound-receiving ultrasonic transducers are combined in a probe. If it concerns separate transmitters and receivers, one also speaks of transceiver probes or SE probes. These are e.g. then preferred when a high Nahaufslösungsvermögen is required. If you send and receive with the same ultrasonic transducer, you are talking about pulse echo probes.

Transceiver probes (SE probes) are used, for example, in the ultrasonic testing of heavy plates. These typically have typical widths of 1 m to 5 m, typical lengths of 3 m to 30 m and typical thicknesses of 5 mm to 150 mm. The article "Operational Experience with a New Full-Plate Ultrasonic Testing System" by A. Weber et al., DGZfP Annual Conference 2013 - DL2.B.2, pages 1 to 8 describes a whole-plate ultrasonic testing system, which is located in a rolling mill immediately behind the cooling bed in the A total of 76 individually pneumatically actuated probe holders are installed in the ultrasonic testing system described above, using SE probes with a nominal frequency of 5 MHz, and the multiple oscillators used have a width of 50 mm and are divided 4 times 304 test channels to be processed individually Probe brackets are installed in two inspection carriages arranged one behind the other in the test direction and offset by a test head width in the transverse direction. As a result, a complete surface inspection (100% test) is achieved after specifying the article.

A known four-way split transmitter-receiver probe has within a rectangular in cross-section Prüfkopfgehäuses a row with four immediately adjacent receiver elements and a single transmitter element which extends over the entire covered by the receiver elements width. For example, reference errors of class FBH-3 (Fiat Bottom Hole with 3 mm diameter) can be detected with high reliability. However, there is an increasing demand, for example in heavy plate testing, for smaller defects, e.g. FBH-2 or FBH-1, 2, with high reliability detect.

The published patent application DE 195 33 466 A1 discloses an ultrasonic test head for non-destructive material testing, which has a plurality of pulse-echo ultrasonic transducers which are arranged with their transmitting / receiving surfaces in a first plane in at least two parallel rows from each other by a gap offset from one another in that each gap between ultrasonic transducers in a row is covered by an ultrasonic transducer of another row. This creates a test head with a large test width, which has a largely constant sensitivity over the entire test width. The published patent application DE 34 42 751 A1 discloses an ultrasonic testing system for sheets with several adjustable to the sheet probes, which are provided in rows transversely to the conveying direction of the sheet and in the conveying direction in several rows in a row with overlap. Each probe has a transmitter and a receiver.

The published patent application DE 196 42 072 A1 discloses composite probe devices having a plurality of local oscillators arranged in a zigzag manner on both sides of a common transmitter oscillator. The transmitting and receiving oscillators are constructed with a common piezoelectric plate, with one of their electrodes being subjected to a division. The local oscillators of different rows partially overlap in the lateral direction, so that a complete test over the entire length covered by the transmitter oscillator is possible. The published patent application DE 10 2008 002 859 A1 discloses a device for non-destructive testing of flat objects by means of ultrasound, the device using matrix phased array probes.

OBJECT AND SOLUTION It is an object of the invention to provide e.g. suitable for use in a ultrasonic heavy plate test suitable test head, which allows easy handling and easy installation in the test system gapless testing large test widths with high reliability, even for small defects in the test specimen.

To achieve this object, the invention provides a test head with the features of claim 1. Advantageous developments are specified in the dependent claims. The wording of all claims is incorporated herein by reference.

The test head has a test head housing which defines a longitudinal direction and a transverse direction orthogonal thereto. The longitudinal direction is that direction which is aligned during operation as parallel as possible to the test direction. The transverse direction is perpendicular to the longitudinal direction and thus in test mode as perpendicular as possible to the test direction. The test head has a plurality of transceiver units, so that it is an ultrasonic Mehrfachprüfkopf. Each of the transceiver units has a transmitter element and an associated receiver element. As a result, an effective test width is defined in the transverse direction in such a way that a test track with the effective test width can be tested during relative movement of the test object relative to the test head along the test direction by the transceiver. The effective test width is usually somewhat smaller than the physical extension of the transceiver unit in the transverse direction, since the sensitivity of the transceiver unit usually drops sharply near the lateral ends, so that effectively only a slightly smaller test width can be used. The transceiver units are arranged in at least two rows lying one behind the other in the longitudinal direction, which each extend in the transverse direction. Transceiver units of different rows are offset from one another in the transverse direction in such a way that receiver elements of mutually offset transceiver units overlap one another in an overlapping area in such a way that the entirety of the transceiver units covers an effective test head test width without any gaps. All transceiver units are arranged in the test head housing.

Furthermore, it is provided that all transmitter elements are electrically connected to a common transmitter connection element of the probe. The transmitter elements are so electrically connected to each other and can be easily controlled synchronously by a common signal. The synchronicity of the transmission signals is thus already given by the test head structure and does not have to be ensured by complicated electronics. Although more than two rows each with one or more transceiver units can be provided, the transceiver units are preferably arranged in exactly two consecutive rows in the longitudinal direction ,

Due to the common arrangement of all transceiver units in the test head housing, it is possible to bring the transceiver units in the production of the probe exactly in their intended positions within the test housing and also to determine the relative positioning of the transceiver units with each other exactly. The geometric arrangement of the transceiver units within the Prüfkopfgehäuses is usually determined by means of support elements and permanently fixed spatially by introducing a suitable potting compound, such as an epoxy resin, and protected against ingress of the coupling agent.

Although a mutual overlap of effective test widths of individual transceiver units could also be achieved in that the transceiver units each installed in a separate Prüfkopfgehäuse and the Einzelprüfköpfe thus obtained are then offset from each other in two or more rows within a Prüfkopfhalters. Corresponding tests have shown, however, that it can be difficult with this combination of several individual probes, to set the required coupling gap precisely enough for each probe separately within the probe holder. On the other hand, if all the transceiver units are located within the same test head housing, the relative arrangement of the transceiver units can be precisely fixed to one another already during the production of the test head, so that the adjustment of the coupling gap for all transceiver units when the test head is installed in the test head holder can be done together quickly and accurately. This ensures a direct comparability of the signal amplitudes of reference errors of all transceiver units of the probe.

By the mutual overlapping in the transverse direction of staggered transceiver units in the overlapping areas, it can be ensured that only the area of the theoretically available test width is used by each transceiver unit in which a sufficiently high sensitivity is present. The width of the mutual overlap is expediently chosen so that the areas with sensitivity drop in the immediate vicinity of the lateral edges of the transceiver units overlap each other so that a significant drop in sensitivity between transversely adjacent transceiver units avoided or significantly reduced over conventional, arranged only in a row multiple oscillators. In some embodiments, the overlap regions have a width of at least 10% of the effective test width of the individual transceiver units, wherein the width of the overlap regions is preferably in the range of 20% to 30% of the effective test width. By adhering to these limits, on the one hand, it can be ensured that the overlap is sufficiently large to prevent significant sensitivity drops in overlapping areas. On the other hand, it can be achieved by not selecting the overlapping areas too broadly so that the required overall test width of the test head (effective test head test width) can be achieved with relatively few individual transceiver units.

In some embodiments, the arrangement is selected such that there is a spacing between a number of adjacent transceiver units which is more than 30% or more than 50% of the effective test width of a transceiver unit. Thus, it can be ensured that no or only a few basically usable test width is "given away".

The transmitter elements and the receiver elements preferably each have a e.g. rectangular plate of piezoelectric material, which acts as a sound-emitting ultrasonic transducer at the transmitter element and as a sound-receiving ultrasonic transducer at the receiver element. These plates are separate elements, which are each provided with electrical contacts. In preferred embodiments, these plates or plates are inclined relative to each other, so that there is a mirror-symmetrical trained to a parting plane roof shape. The parting plane extends in the transverse direction. A roof angle may e.g. 6 °, but possibly also more or less.

Preferably, located in the parting plane (plane of symmetry of the roof assembly) between the ultrasonic transducers, a partition of an ultrasonic damping material. This is used, inter alia, the acoustic decoupling of transmitter element and receiver element of a transceiver unit, so that the sound transmission can be done only indirectly via the coupled in the test operation specimen material. The partition can also serve the electrical decoupling of the ultrasonic transducer on the transmitting side and the receiving side. Advantages of the new concept can already be utilized if only two transceiver units are offset transversely relative to one another within the test head housing and are or are arranged longitudinally in two different rows. Much more transceiver units can also be integrated, for example five to ten transceiver units. In preferred embodiments, however, it is provided that exactly three or exactly four or exactly five transceiver units are arranged in the Prüfkopfgehäuse, wherein a first and a third transceiver adjacent to each other in a first row and a second transceiver symmetrically offset to the gap first and third transceiver unit is arranged in a second row. If four transceiver units are provided, the fourth transceiver unit is preferably arranged in the second row with transverse spacing from the second transceiver unit. An optionally present fifth transceiver unit can be arranged in the first row.

When optimizing the number, the dimensions and the distribution of transceiver units, it should be taken into account on the one hand that the individual signal amplitude of a receiver is higher for a given size error, the smaller the effective test width or the larger the ratio between the defect size and the effective test width. In that regard, a higher number of transceiver units, e.g. six to ten or more, be favorable in terms of large signal amplitudes. On the other hand, the number of transceiver units also increases the technological outlay for the correctly positioned accommodation and the corresponding test electronics and the evaluation. If, in contrast, only two transceiver units are arranged one after the other in two rows, then it may be the case that the individual effective test widths must become relatively large, as a result of which the signal amplitude may not be sufficiently high, in particular for small defects. Therefore, a number of exactly three or exactly four or exactly five transceiver units in the probe is currently considered favorable.

The transceiver units arranged in different rows can all have the same orientation of their transmitter elements and receiver elements with respect to the longitudinal direction or test direction. For example, all transmitter units can radiate in the same direction obliquely forward or obliquely backwards (viewed in the test direction). In some embodiments, on the other hand, provision is made for the transceiver units of the test head to be distributed in a first row and in a second row, with the transmitter elements arranged in different rows arranged transceiver units facing each other in the central region of the probe (viewed in the longitudinal direction) are and the plates of the transmitter elements due to the Roof shape are so inclined relative to each other that the transmitter elements radiate due to the roof angle in opposite oblique directions each from the inside out. As a result, a better acoustic decoupling of the transceiver units located in different rows can be achieved solely on the basis of the main emission directions facing away from one another. It is possible to design the test head housing so that the mutually offset transceiver units each have adapted subsections of the test head housing into which they can be fitted. This could lead to a complex outer contour of the Prüfkopfgehäuses with corners and inner angles. Preferably, the Prüfkopfgehäuse has a rectangular cross-sectional shape. In particular, the test head housing may be sized and shaped to conform to the test head housings of conventional multi-split multiple oscillators in cross-sectional shape and dimension so that probes according to the claimed invention can readily be replaced in exchange for conventional multi-split multiple oscillators. It would also be possible to electrically connect some receiver elements or all receiver elements and connect them to a common receiver connection element. Preferably, however, it is provided that each of the receiver elements is electrically connected to a separate receiver connection element of the probe. Thus, an accurate assignment of individual error signals to a location or a narrow test track in the transverse direction is possible, whereby the localizability of errors in the transverse direction can be refined.

The transmitter connection element and the receiver connection elements can be housed in a common connector housing, so that the electrical connection of the probe after mounting in the probe holder is very easy and possibly also requires the use in existing test systems no adaptation of the wiring.

Preferably, located between the transmitter element and the receiver element for acoustic decoupling a partition wall (sound dam) made of an ultrasonic damping material, such as cork, foam or the like. In some embodiments, it is alternatively or additionally provided that at least one partition made of an ultrasound-damping material, for example cork, is arranged between transceiver units which are adjacent in a row. As a result, crosstalk in the transverse direction can be reduced or avoided. If two or more transceivers are arranged side-by-side in a row, they may have a common divider which encloses the transmitter elements and the receiver elements of the transceivers. Receiving units acoustically decoupled from each other. As a result, the production costs for the acoustic decoupling can be reduced.

For acoustic optimization of the test head, each transceiver unit can be assigned a damping body, which is located opposite that side of the test head which is to be brought into sound-conducting contact with the test object surface. Although a separate damping body can be provided for each transceiver unit, the test head housing preferably has a single damping body, which acts as a damping body of all transceiver units. As a result, among other things, the production is simplified. The invention also relates to an ultrasonic testing system for non-destructive testing of a test piece under relative movement of the test piece relative to the test head along a test direction, wherein the ultrasonic test system has one or more of the test heads according to the invention. The ultrasonic testing system may in particular be an ultrasonic heavy plate testing system. Brief description of the drawings

Further advantages and aspects of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are explained below with reference to the figures.

Fig. 1 shows an ultrasonic probe according to an embodiment of the invention in a plan view from the active side of the probe;

Fig. 2 shows a sectional view of the test head of Figure 1 in an installed state within a Prüfkopfhalters.

Fig. 3 shows a schematic plan view of an embodiment with another arrangement of sound-insulating partitions; Fig. 4 shows a schematic plan view of a further embodiment with another arrangement of sound-insulating partitions; and

5 shows a sectional view of a variant of the embodiment shown in FIG. 2 with a different sequence of transmitter elements and receiver elements. Detailed description of the embodiments

The schematic Fig. 1 shows a test head 100 according to an embodiment of the invention in a plan view of the active side of the probe, so that side with which the probe is brought into the vicinity of the surface of a test specimen to be tested. Fig. 2 shows a sectional view. The test head is intended for use in a fully automatic ultrasonic heavy plate test system in which a plurality of nominally identical probes are used. The test head preferably operates at a nominal frequency of about 4 or 5 MHz and combines in the example three sound-emitting and three sound-receiving ultrasonic transducers, so that it is a transceiver probe (SE probe).

The test head has a preferably milled metallic Prüfkopfgehäuse 1 10, which has a substantially rectangular cross-sectional shape in the plane of Fig. 1, wherein the width in the transverse direction Q is more than twice as long as the length in the longitudinal direction L. In the example, the case Width in transverse direction about 65 mm, while the perpendicular measured length is about 24 mm to 25 mm. On the side of the active surface 120, the test head housing is open (see Fig. 2). At the back of the active surface opposite the test head housing is closed except for passages for electrical lines.

As the schematic Fig. 2 shows, the test head 100 is used when setting up the test facility in a probe holder 200, which is fastened together with a plurality of nominally identical probe holder on a surface test car of the test system. The probe holder 200 carries on its side facing the specimen 290 a so-called wear sole 210 in the form of a solid plate made of a wear-resistant material, such as stainless steel with carbide inserts and / or a hardened steel material. For the test, the test head holders are delivered in the direction of the test piece 290 so that the wear soles come into contact with the test piece surface 292 and slide thereon as the test piece moves in the test direction 295 relative to the test head holder. The test head is installed in the test head holder such that the longitudinal direction L of the test head runs as parallel as possible to the test direction 295. The orthogonal to the longitudinal direction and transverse direction extending high direction H is then as perpendicular as possible to the specimen surface. Typical test speeds in test mode after adjusting all test head holders are usually e.g. be between 0.5 m / s and 1 m / s.

The wear sole 210 has a rectangular cutout or a recess 215, which extends from the contact surface 212 to the inside goes through and in the longitudinal direction L and transverse direction Q is dimensioned so that the test head 100 can be introduced with a small side clearance from the interior of the probe holder into the recess. At the rear end of the test head, ie on the side facing away from the active surface 120, there is a support plate 220, which serves for the attachment and vertical alignment of the test head in the test head holder 200. When installing the probe in the probe holder of the probe is positioned so that between the flat active surface 210 of the probe and that plane which is formed by the contact surface 212 of the wear sole 210, a so-called coupling gap SP as constant thickness over the width of the probe remains , The thickness D is often on the order of about 0.25 mm to 0.35 mm. In test mode, this gap fills with the coupling fluid, usually water. The exact, not wedge-shaped adjustment of the coupling gap, in particular in the longitudinal direction is an essential prerequisite for reliable ultrasonic testing.

The test head 100 is designed to have a relatively uniform high sensitivity over its entire effective test head width PKPB without major local delays in sensitivity. For this purpose, three nominally identical transceiver units are arranged in the housing interior enclosed by the test head housing in the example case, namely a first transceiver unit 150-1, a second transceiver unit 150-2 and a third transceiver unit 150-3. Each of the transceiver units comprises a single transmitter element T1, T2 or T3 and a single, the transmitter element associated receiver element R1, R2, R3. The transmitter elements and the receiver elements each have a thin rectangular plate of piezoelectric material, which acts as a sound emitting ultrasonic transducer at the transmitter element and as a sound-receiving ultrasonic transducer at the receiver element. Contacts on the front and back are present, but not shown. The rectangular plates extend parallel to each other in the transverse direction Q and are inclined relative to each other, so that there is a mirror-symmetrical trained to a parting plane roof shape, eg with a roof angle of, for example, 6 °. (Figure 2). In the parting plane (symmetry plane of the roof arrangement) runs between the ultrasonic transducers a partition wall 152-1 made of an ultrasound-damping material. The partition wall, which is preferably made of a cork material, serves for the acoustic decoupling of transmitter element and receiver element of a transceiver unit, so that the sound transmission can take place only indirectly via the test object material coupled in the test mode. The partition also serves the electrical decoupling of the ultrasonic transducer on the transmitting side and the receiving side. The sequence of transmitter element and receiver element of a transceiver unit in the test direction can also be the reverse of the illustrated sequence. Examples are explained in connection with FIG. 5

Above the transceiver elements, a single damping body 260 is inserted in the interior of the rear-side closed test head housing 110, which serves as rear-side sound damping for all transceiver units. The free volumes of the housing interior between the transmitter elements, the receiver elements and partitions is filled up to the level of the active surface 120 with a potting compound made of plastic, so that the electrically operated elements of the probe are sealed watertight. Each of the transceiver units has a transversely measured effective width PB1, etc. which is slightly (about 10% to 20%) less than the physical extent of the transmitter element T1 and the transceiver element R1 in the transverse direction. To illustrate the effective test width of the first transceiver 150-1, Figure 1 shows a curve E1 representing a typical signal amplitude curve over the length of the element measured in transverse direction Q with respect to a reference error FBH-2. The signal amplitude is a measure of the sensitivity. Characteristic of this sensitivity curve is a relatively broad plateau of relatively high recoverable signal amplitude symmetrical to the center of the transceiver with a flat local sensitivity drop in the center of the element, two local maxima M1, M2 closer to the outer edges of the element, and a steep decrease in sensitivity close to the ends in the transverse direction. The effective check width PB1 may, for example, be defined to denote that region in which the signal amplitude is reduced by e.g. 4 dB lower than in the local maxima. The other transceiver units have respective effective test widths PB2, PB3. The effective test widths may be e.g. at 20 mm or more. When the specimen 290 moves relative to the test head along the test direction 295, a test track is scanned by each of the transceiver units whose width (in the transverse direction) corresponds to the effective test width of the respective transceiver unit.

The transceiver units are arranged relative to one another such that their effective test widths and the three transversal scan tracks sensed by the transceiver units partially overlap so that scanning across the entire test head test width can be done with high sensitivity. For this purpose, the transceiver units are arranged in two straight rows 155-1, 155-2 arranged one behind the other in the longitudinal direction L, each extending in the transverse direction Q. The first transceiver 152-1 and the third transceiver 152-3 are in the first row 155-1 at a mutual distance DQ in the transverse direction Q mounted so that the dividing planes between the respective transmitter elements T1, T3 and the receiver elements R1, R3 coincide or aligned. The distance DQ measured in the transverse direction Q between the two transceiver units of the same row is between 40% and 60% of the respective width of the transceiver units in this direction.

The second transceiver unit 150-2 is arranged in the second row 155-2, that is offset in the longitudinal direction relative to the first and third transceiver unit. The second transceiver unit is located symmetrically to the other transceiver units so that the gap between the transceiver units of the first row is completely covered. The second transceiver unit 152-2 extends on both sides in the transverse direction so far that an outer portion in the longitudinal direction is behind an outer portion of the transceiver units located in the first row. It is thereby achieved that the transceiver units of different rows (first row, second row) in the transverse direction Q are offset from one another in such a way that the receiver elements of staggered transceiver units and also the test tracks scanned by these transceiver units in an overlap area U 1 -2 or U2-3 overlap so that the entirety of the transceiver covers the effective Prüfkopf- check width PKPB gapless and without significant sensitivity drop. The width of the overlapping areas U 1 -2 and U2-3 measured in the transverse direction Q is approximately 15% to 20% of the effective test width PB1, PB2, PB3 of the individual transceiver units. This ensures, on the one hand, that the specimen can be tested with high sensitivity even in the overlap region, and, on the other hand, with a relatively small number of only three transceiver units, the entire effective probe test width can be covered. FIG. 1 clearly shows that all transmitter elements T1, T2 and T3 of the test head 100 are connected to a common transmitter connection element AT of the test head. From each receiver element R1, R2 and R3, a separate electrical line leads to a separate receiver connection element AR1, AR2, AR3. The transmitter terminal AT and the receiver terminals AR1, AR2 and AR3 are housed in a common plug housing (multiple plug), so that the probe can be conveniently connected to the ultrasonic electronics of the ultrasonic inspection system by connecting to the corresponding socket.

There are different possibilities for the acoustic and electrical decoupling of transmitter elements and receiver elements. In the embodiment of Figures 1 and 2 Each transceiver has its own partition 152-1 between transmitter element and receiver element. The partitions are not connected to each other. In the embodiment of the test head 300 in Fig. 3, there is a common partition wall 352 for the two in the same row (first row) arranged transceiver units. The production can be simplified. In the embodiment of a test head 400 in FIG. 4, there is a transverse partition 452 between the first row transceiver units and the second row transceiver unit. Furthermore, there are further longitudinal walls on the narrow sides of the transceiver unit. In particular, partitions are arranged on the mutually facing sides of the transceiver units of the first row, so that a possible crosstalk within the probe is even better suppressed than in embodiments without such partitions.

In the embodiments of FIGS. 1 to 4, the transmitter elements T1, T2, etc. of the various transceiver units are each arranged such that all transmitter elements lie in a mutually parallel, obliquely opposite to the LQ plane planes, so that all transmitter elements of in Longitudinal L L consecutive rows due to the inclination in the same direction radiate. The emission direction of the three transmitter elements T1, T2 and T3 of the embodiment of FIG. 1 would therefore radiate obliquely forward in this direction when the probe is moving in the longitudinal direction L (upward in FIG. 1).

FIG. 5 shows a variant of the embodiment shown in FIGS. 1 and 2 in a sectional view analogous to FIG. 2. For clarity, the same reference numerals will be used. The only difference from the variant of FIG. 2 is that the transmitter elements T1 and T2 of the mutually parallel rows one behind the other transceiver units are not in mutually parallel planes, but are placed obliquely against each other. The same applies to the receiver elements R1, R2. As a result, it is achieved, inter alia, that the transmitter elements T1, T2 of the transceiver units in the longitudinal direction immediately following one another are remote from the sound-radiating surfaces and adjoin one another in each case in the overlapping regions. Due to the opposite inclination, the main radiation directions (double arrows) are oriented so that the transmitter elements transmit the ultrasound from inside to outside. The main emission directions thus have opposite components in the longitudinal direction. This can be compared to the z. B. shown in Fig. 1, a further improved acoustic decoupling of lying in different rows transmitter elements can be achieved. The transmitter elements can thus at the two-row arrangements each, seen in the longitudinal direction, be arranged in the central region of the probe and sound due to their inclination due to the roof angle to both sides to the outside (in the longitudinal direction).

Corresponding modifications are also possible in the embodiments of FIGS. 3 and 4. Thus, for example, in the variant derived from FIG. 3, the arrangement of transmitter elements T2 and receiver elements R2 can be exchanged so that the transmitter element T2 directly adjoins the transmitter elements T1 and T3 of the two transmitter-receiver units of the other row. Also in the arrangement of FIG. 4, a corresponding modification may be provided, so that the transmitter element T2 is directly adjacent to the partition wall 442, while the receiver element R2 is externally, d. H. near the probe housing.

The ultrasonic test is based on the fact that sound waves propagate at different speeds in different media. They are partially reflected at interfaces of different wave impedance. As the difference in the wave impedance increases, so does the reflected component. Changes in the acoustic properties at interfaces in the region of a defect or defect in the interior of the test specimen to be tested reflect the sound pulse emitted by the transmitter element and send it to the receiver element in the test head. As errors (or discontinuities) come e.g. Voids (cavities), inclusions, cracks or other separations in the structure into consideration. In the pulse-echo method, the elapsed time between transmission and reception is measured. Based on the measured time difference, a signal can be generated. This signal can be used to determine the location of a discontinuity and the size of the fault or discontinuity by comparing it to a replacement reflector (eg a flat bottom hole (FBH), a groove or a transverse bore) , related to the candidate and documented in various ways, immediately or later.

Experiments with conventional quad split transceiver probes have shown that for replacement reflectors down to class FBH-3 (3mm diameter flat bottom bore) they can have sufficient sensitivity over the entire effective probe test width. However, it was found that the detection of reference errors with FBH-2 or smaller is often not sufficiently reproducible. This limitation of sensitivity is attributed, inter alia, to the areas of lower sensitivity at the junctions between receiver elements adjacent in a row. Due to the novel arrangement of transceiver units within the probe with overlapping Test tracks or effective test widths according to the embodiments of the present invention, reference errors class FBH-2 or smaller (eg down to FBH-1, 2 or FBH-1 or less) can now be detected with good reproducibility.

Claims

claims

1 . Test head (100) for an ultrasonic testing system for non-destructive material testing with relative movement of a test object (290) opposite the test head along a test direction (295) with:

a test head housing (110) which defines a longitudinal direction (L) in the test direction and a transverse direction (Q) perpendicular to the test direction; and

a plurality of transceiver units (150-1, 150-2, 150-3), each transceiver unit having a transmitter element (T1, T2, T3) and an associated separate receiver element (R1, R2, R3) and transversely (Q ) defines an effective test width (PB1, PB2, PB3) in such a way that during relative movement of the test object relative to the test head along the test direction by the transceiver unit, a test track with the effective test width can be tested, wherein

the transceiver units are arranged in at least two rows (155-1, 155-2) running one behind the other in the longitudinal direction (L) and extending transversely (Q); Transceiver units of different rows in the transverse direction (Q) are offset from one another in such a way that receiver elements (R1, R2, R3) of mutually offset transceiver units in an overlap region (U1 -2, U2-3) overlap each other, so that the totality of Transmitter / receiver units fully covers an effective test head test width (PKPB);

all transceiver units are arranged in the test head housing (110), and all transmitter elements (T1, T2, T3) are electrically connected to a common transmitter connection element (AT) of the test head.

2. Test head according to claim 1, characterized in that the overlapping regions (U1 -2, U2-3) in the transverse direction have a width of at least 10% of the effective test width (PB1, PB2, PB3), wherein the width of the overlapping regions preferably in the range from 20% to 30% of the effective test width.

3. Test head according to claim 1 or 2, characterized in that between in a row (155-1) adjacent transceiver units (150-1, 150-2), a distance (DQ), which is more than 30% of the effective test width (PB1, PB2, PB3) of a transceiver unit.

4. Probe according to one of the preceding claims, characterized in that the transmitter elements (T1, T2, T3) and the receiver elements (T1, T2, T3) each comprise a plate of piezoelectric material, wherein the plates of a transmitting Receiving unit are inclined relative to each other, so that there is a mirror-symmetrically formed to a parting plane roof shape, preferably in the parting plane between the plates, a partition wall (152-1) extends from an ultrasound-damping material.

5. Probe according to one of the preceding claims, characterized in that in the Prüfkopfgehäuse (1 10) exactly three or exactly four transceiver units (150-1, 150-2, 150-3) are arranged, wherein a first and a third Transceiver unit side by side in a first row (155-1) and a second transceiver unit (150-2) symmetrically offset from the first and the third transceiver unit in a second row (155-2) is arranged.

6. Probe according to one of claims 4 or 5, characterized in that transmitting-receiving units (150-1, 150-2, 150-3) distributed in a first row (155-1) and in a second row (155-2 ), wherein the transmitter elements arranged in different rows transmit-receive units facing each other are arranged in the central region of the probe and the plates of the transmitter elements are so inclined relative to each other due to the roof shape that the transmitter elements due to the roof angle in operation in opposite oblique directions each radiate outward.

7. Test head according to one of the preceding claims, characterized in that the test head housing (1 10) has a rectangular cross-sectional shape.

8. Probe according to one of the preceding claims, characterized in that each of the receiver elements (R1, R3, R3) is electrically connected to a separate receiver connection element (AR1, AR2, AR3) of the probe.

9. Probe according to one of the preceding claims, characterized in that the transmitter connection element (AT) and the receiver connection elements (AR1, AR2, AR3) are accommodated in a common connector housing.

10. Probe according to one of the preceding claims, characterized in that in the test head housing (1 10) a single damping body (260) is arranged, which acts as a damping body of all transceiver units.

1 1. Test head according to one of the preceding claims, characterized in that the test head has at least one partition made of an ultrasound-damping material, which is arranged between adjacent in a row transceiver units.

12. Ultrasonic testing system for non-destructive testing of a test piece under relative movement of the test piece relative to the test head along a test direction, wherein the ultrasonic test system comprises one or more of the probes according to one of the preceding claims.