WO2011045201A1

WO2011045201A1 - Device for non-destructive inspection of the interior of components and transducer for the same having improved ultrasonic coupling

Info

Publication number: WO2011045201A1
Application number: PCT/EP2010/064799
Authority: WO
Inventors: Julian Theobald; Stefan Holl; Klaus Krämer
Original assignee: Institut für Akustomikroskopie Dr. Krämer GmbH
Priority date: 2009-10-15
Filing date: 2010-10-05
Publication date: 2011-04-21
Also published as: DE102009044254A1

Abstract

The invention relates to a device for non-destructive inspection of the interior of components (2). A liquid coupling medium is provided between the component (2) and a free end (12a) of the at least one transducer (12). A displacement device (9) is provided for inspecting the entire component (2), displacing the at least one transducer (12) in a serpentine manner over the component (2) substantially along a first movement direction (20a) and along a second movement direction (20b) opposite the first movement direction (20a) in the liquid coupling medium (8). The at least one transducer (12) has an extension (27a, 27b) in the direction of the first movement direction (20a) and in the direction of the second movement direction (20b) for reducing turbulence.

Description

DEVICE FOR NON-DESTRUCTIVE INSPECTION OF THE INTERIOR OF COMPONENTS AND TRANSDUCERS THEREFORE WITH IMPROVED ULTRASOUND COUPLING

The present invention relates to a device for nondestructive inspection of the interior of components. The device comprises an ultrasonic arrangement with at least one transducer which is assigned to the component. Between the components and a free end of the at least one transducer, a liquid coupling medium is provided. For the inspection of the entire component, a traversing device is provided, which moves the at least one transducer in a meandering manner substantially along a first direction of movement and along a second, opposite to the first direction of movement, in the liquid coupling medium on the component.

The invention also relates to a transducer. The transducer is suitable for trouble-free inspection of the interior of components. The transducer has a free end from which can be emitted from ultrasonic waves and from which an echo of the emitted ultrasonic waves can be received.

German patent application DE 10 2006 032 431 A1 discloses a method for detecting mechanical defects in a semiconductor material consisting of a rod piece. The semiconductor material has at least one flat surface and a thickness of 1 cm to 100 cm measured perpendicular to this surface. In the method, the flat surface of the rod piece is ratcheted with at least one transducer which is coupled via a liquid coupling medium to the flat surface of the rod piece.

The unpublished German patent application DE 10 2008 002 832.0 discloses a method and a device for the non-destructive detection of defects in the interior of semiconductor material. The semiconductor material has a

Length, a cross-sectional area and along the length-oriented lateral surface. An ultrasonic arrangement is associated with the semiconductor material. Likewise, a device for generating a relative movement between the ultrasonic arrangement and along the length L of the lateral surface of the semiconductor material is provided.

U.S. Patent 4,170,144 discloses an apparatus for scanning a material. With the device it is possible to determine changes in the thickness or elastic constants in the interior of a material. This involves moving a transducer over the surface of the material. Based on the ultrasound echo scattered back from the material, it is possible to conclude the changes in thickness or elastic constants. The ultrasonic waves emanating from the transducer are coupled via a coupling medium to the component to be examined. U.S. Patent Application 2007/001215 A1 discloses a method and apparatus for coupling ultrasound between a transducer and an object. A scanning element is attached to an ultrasound transducer to thereby form an integral component with the transducer. In this case, the ultrasound emitting surface of the transducer is arranged in a liquid-filled chamber in an upper chamber. The ultrasound transducer is thereby moved relative to the object to be scanned.

International Patent Application WO 02/40987 discloses a method and apparatus for acoustic, microscopic examination of flat substrates. The substrates to be examined are transferred to a wet cell, in which the ultrasound is coupled.

The prior art does not address the problem that occurs at higher scanning speeds. If the transducer is moved at a higher speed in the liquid coupling medium, turbulences form or bubbles adhere to the free end of the transducer, which can lead to a falsification of the measurement result. To avoid this, it is only possible in the prior art to make the scan speed of the transducer not too large. The maximum speed, with which the transducer can be moved in the liquid coupling medium, so far is one meter per second.

The invention has for its object to provide a device for non-destructive inspection of the interior of components, with which it is possible in a shorter time and trouble-free to inspect the interior of a component nondestructive.

The above object is achieved by an apparatus comprising the features of claim 1.

A further object of the invention is to transform a transducer for nondestructive inspection of the interior of a component in such a way that higher traversing speeds in the coupling medium are possible with the transducer, without impairing the inspection quality and the image recording carried out with the transducer.

The above object is achieved by a transducer comprising the features of claim 6. In order to inspect the entire component, it is necessary to meander the transducer in the apparatus for nondestructive inspection of the interior of components meandering over the surface of the component. In this case, the entire surface of the component with the at least one transducer is scanned meandering. In this case, the transducer is guided over the surface of the component in a first direction of movement and in a second direction of movement. In this case, the first direction of movement is opposite to the second direction of movement. The transducer according to the invention is designed such that it has formed an extension pointing in the direction of the first movement direction and in the direction of the second movement direction. The extension is designed such that it during the movement of the

Transducers in liquid coupling medium minimizes the turbulence occurring. The extensions of the at least one transducer have a height. When using the at least one transducer, the extensions immerse at least half of the height in the liquid coupling medium. Each of the extensions has a length and a maximum width. The length is greater than the maximum width. The maximum width is at least equal to the diameter of the transducer at the free end of the transducer.

The extensions of the transducer have the same shape both in the first direction of movement and in the second direction of movement. Preferably, the extensions have the shape of an isosceles triangle. The two legs meet in the direction of movement at an acute angle to each other. The apex of the isosceles triangle, where the legs meet at an angle, is a rounded tip.

For an advantageous and non-destructive inspection of the interior of components, a transducer is used that carries an element that has two opposing extensions formed. The transducer has a free end which delivers the ultrasonic waves required for non-destructive inspection of the component and which receives echo of the ultrasonic waves from the component to be examined. The extensions of the element fastened to the transducer have in the first direction of movement and in the second direction of movement when the transducer is in use. It should be noted that the first direction of movement is opposite to the second direction of movement.

The extensions of the element, which is attached to the transducer, have at least one height, one length and a maximum width. The length is greater than the maximum width. The maximum width is at least equal to a diameter of the at least one transducer at the free end of the at least one transducer. The transducers used are piezoelectric transducers for ultrasound examinations of the components. The transducers convert an electrical voltage into an ultrasonic signal and vice versa. This is done with the help of a piezo element. Piezo elements are materials which change their shape when an electrical voltage is applied. Conversely, mechanical pressure, which can be generated by the echo, causes a piezoelectric element to cause the piezoelectric element to generate an electrical voltage. These effects are exploited by a transducer. In a transducer is a piezo element that is made of zinc oxide (ZnO). If an electrical voltage is applied to the transducer, the piezoelectric element deforms due to the properties described. If the electrical voltage is applied at a certain frequency, the deformation of the piezo element in the transducer also takes place at a frequency at which acoustic waves are generated. Depending on the shape and size of the piezo element and the material, ultrasonic signals with different frequency or bandwidth are generated. These acoustic waves or ultrasonic waves are focused in the transducer and focused through a series of lenses and filters. The generated ultrasonic waves leave the transducer via another lens (calotte) on the underside or at the free end of the transducer. For the generation of an image on the component to be inspected, use is made of the reversal of the piezoelectric effect. If a reflected ultrasonic signal (echo) hits the transducer, these ultrasonic waves are directed to the active element inside the transducer. The ultrasonic waves cause a deformation of the piezoelectric element there. The piezo element converts the deformation into a corresponding electrical voltage. From the height and type of electrical voltage, the ultrasound image is generated by the component to be examined.

In the following, embodiments of the device according to the invention and the transducer according to the invention and their advantages are explained in more detail with reference to the attached figures.

FIG. 1 shows a schematic view of a device for nondestructive detection or inspection of defects in the interior of components. Figure 2 shows a schematic view of the structure of a transducer for the delivery and reception of ultrasonic waves.

FIG. 3 shows a schematic view of how a component to be examined is scanned meander-shaped with a transducer.

FIG. 4 shows an illustration of a transducer according to the prior art

Technology.

Figure 5 shows a perspective view of a transducer according to the present invention.

FIG. 6 shows the illustration of the turbulence and blistering in the

Movement of a Transducers in liquid coupling medium according to the prior art.

Figure 7 shows an enlarged view of the transducer during movement in liquid coupling medium according to the prior art.

FIG. 8 shows a view of the prior art transducer during movement at the point of reversal of the meandering scanning structure.

Figure 9 shows an image taken with the prior art transducer in which defects in the image are discernible.

FIG. 10 shows a representation of the movement of the invention

Transducers in the liquid coupling medium. Figure 1 1 shows a schematic plan view of the transducer according to the present invention.

FIG. 12 shows a schematic side view of the transducer in association with the inspecting component.

For identical or equivalent elements of the invention, identical reference numerals are used. Furthermore, for the sake of clarity, only reference Chen in the individual figures, which are required for the description of the respective figure.

FIG. 1 shows a schematic view of an arrangement 1 for nondestructive inspection of components 2. The arrangement 1 described in FIG. 1 is state of the art. With the arrangement 1 components 2 can be examined with any cross-section Q. The component 2 to be examined is positioned in a container 6 that is filled with a liquid coupling medium 8. In the illustration shown here, the device 10 for non-destructive inspection of the component 2 has a plurality of transducers 12. Ultrasonic signals are emitted by the transducers 12 and coupled to the component 2 via the coupling medium 8. The double arrow 9 indicates that the plurality of transducers 12 are moved along the component 2 to be examined in order thereby to detect the entire component 2 and to generate a corresponding image of the interior of the component 2 from the ultrasound echo returning from the component 2. The plurality of transducers 12 are accordingly moved along the surface 2 a of the component 2. During the process of the transducer 12, these submerge into the liquid coupling medium 8.

FIG. 2 shows the embodiment of a transducer 12 which is used to generate an ultrasound image. The transducer 12 has a connection 7, via which it can be connected to other components 2 of the arrangement 1. About this connection 7 z. B. led the electrical connections. Furthermore, this connection 7 also represents the mechanical connection. At the lower end of the transducer 12, the active element 14 is provided. The active element 14 is the piezo element with which the sound waves are generated and which receives the sound waves coming back from the component 2 and correspondingly converts them into electrical signals. Furthermore, a plurality of electrodes 1 1 are provided, which are responsible for the corresponding conversion of the signals. The voltages are supplied to the transducer 12 via a plurality of electrical leads 17 or the voltages for the corresponding conversion are dissipated by the transducers 12. Likewise, an electrical circuit 18 is provided which is suitable for the conversion of the ultrasonic waves in electrical signals is responsible. Likewise, the application of the electrical voltage to the corresponding active element 14 is controlled via the electrical circuit 18. The electrical leads 17, the electrical circuit 18 and the active element 14 are accommodated in a housing 19. On the housing inner wall is an additional tube 16, which supports the active element 14. The housing 19 is closed by an end plate 13 and thus forms the free end 12 a of the transducer 12. Inside the housing 19, at least the lines 17 are surrounded by a filling 15. This filling 15 diffusely attenuates the emitted ultrasonic signals. The end plate 13 is the free end 12a of the transducer 12 and is located between the lens and the coupling medium 8. Further, the end plate 13 protects the transducer 12 from damage.

Figure 3 shows the schematic representation of how the component 2 is scanned with the transducer 12. The transducer 12 is guided in a meandering manner over the surface 2a of the component 2. The meandering movement of the transducer 12 is thus composed of a first direction of movement 20a and a second direction of movement 20b. In this case, the first movement direction 20a is parallel to the second movement direction 20b and the second movement direction 20b is opposite to the first movement direction 20a. At reversal points 22, the transducer 12 is transferred from the first direction of movement 20a in the second direction of movement 20b. Thus, it is possible to scan the entire surface 2 a of the component 2 with the transducer 12 and thus to acquire an ultrasound image from an inner region of the component 2.

FIG. 4 shows a transducer 12, as used in accordance with the prior art. As already mentioned in the description of FIG. 2, the transducer 12 is connected to a carrier 24 via the connection 7. The transducer 12 has a substantially cylindrical shape according to the prior art. From the free end 12a of the transducer 12, the ultrasonic signals required for the non-destructive examination of the component 2 are emitted and the ultrasound signals required for the image display receive. The free end 12a and a part of the transducer 12 thus immerse into the liquid coupling medium 8.

FIG. 5 shows the embodiment according to the invention of the transducer 12 in the region of the free end 12a. In the cylindrical portion of the transducer 12, an element 27 is attached. The element 27 has two opposite extensions 27a and 27b. In use of the transducer 12 according to the invention, the first extension 27a in the first direction of movement 20a and the second extension 27b in the second direction of movement 20b.

FIG. 6 shows a representation of the transducer 12 according to the prior art as it is guided in the liquid coupling medium 8 via the component 2 (not shown here). The transducer 12 is guided along the first direction of movement 20a. As can be seen clearly from FIG. 6, considerable turbulence 30 and increased bubble formation 31 occur in the coupling medium 8. The turbulence 30 and the bubble formation 31 are caused by the movement of the transducer 12 in the coupling medium 8. The higher the speed of the transducer 12 in the first direction of movement 20a or the second direction of movement 20b, the greater the turbulence 30 and the bubble formation 31.

FIG. 7 shows an enlarged view of the transducer 12, which is guided along the direction of movement 20a by the coupling medium 8. As can be clearly seen in FIG. 7, the movement of the transducer results

12 a reinforced bubble formation 31 in the coupling medium 8. In addition, due to the rapid movement of the transducer 12 in the coupling medium 8, a portion of the liquid rises on the transducer 12 and thus leads to considerable turbulence 30 in the coupling medium 8. FIG. 8 shows the free end 12a of the transducer 12 during the movement in the coupling medium 8. Precisely at the point of reversal 22 between the first direction of movement 20a and the second direction of movement 20b, an increased blistering 31 occurs. Likewise, at the turning point 22, considerable turbulence 30 occurs. This is easily conceivable, since at the turning point 22 the speed of the transducer 12 in the first direction of movement 20a must be reduced and the transducer 12 at the reversal point 22 must be accelerated again in the second direction of movement 20b to a certain speed. FIG. 8 shows the situation that an air bubble adheres to the free end 12a of the transducer 12. FIG. 9 shows an ultrasound image 33 from the interior of the component 2. It can be clearly seen that the image has a plurality of black stripes 35 which contain no image information. These black stripes 35 are due to the fact that in the prior art transducer 12, just at the reversal point 22, air bubbles adhere to the free end 12a of the transducer. The air or air bubbles that adhere to the free end 12a of the transducer 12 completely reflect the ultrasound. Thus, fragment-wise line failures 35 result at the acoustic image at the locations.

FIG. 10 shows the transducer 12 according to the invention with the element 27 fastened to the transducer 12, which is suitable for reducing the turbulence during the movement in liquid coupling medium 8. The element 27 has a first extension 27a and a second extension 27b. Through these extensions 27a, 27b, it is possible that even at high scanning speeds of up to about 1.5 meters per second, the turbulences 30 and also the blistering 31 in the coupling medium 8 are reduced. FIG. 11 shows a plan view of the transducer 12 according to the invention with the element 27 reducing the turbulence 30. The element 27 has a first extension 27a and a second extension 27b. The first extension 27a is in the direction of movement 20a and the second extension 27b is aligned in the direction of movement 20b. Each of the extensions 27a and 27b has a width B and a length L. The length L is greater than the width B of the

Extension 27a or 27b. Likewise, the two extensions 27a and 27b are formed such that their width B is at least equal to the diameter D of the transducer 12. The extensions 27a and 27b of the element 27 both have the same shape. The shape of the extensions 27a and 27b is an isosceles Triangle. The legs 28 of each of the extensions 27a or 27b include an acute angle a. The tips 29 of the extensions 27a and 27b are rounded.

FIG. 12 shows a side view of the transducer 12 with the element 27, which ensures a reduction of turbulence formation during the process of the transducer 12 in the coupling medium 8. The element 27 is attached to the transducer 12 such that the free end 12a of the transducer 12 projects beyond the element 27. The free end 12 a of the transducer 12 is arranged opposite to the component 2, of which it is necessary to inspect the interior of the component 2. The transducer 12 dives so far into the coupling medium 8, that at least the line 8a of the liquid coupling medium 8 to half of the height H of the element 27 extends. Since the element 27 with the two extensions 27a and 27b forms a flow-optimized form of the transducer 12, turbulences 30 as well as air bubbles and the wave formation in the coupling medium 8 are thereby significantly reduced. Due to the embodiment of the transducer 12 according to the invention, it is possible to increase the maximum scanning speed with an ultrasound microscope from 1 meter per second to 1.5 meters per second. With the ultrasonic microscope, a maximum magnification of 250x can be achieved. A minimum scanning field of 500 μιτι to 500 μιτι is possible. The transducer 12 emits sound frequencies in the range of 1 MHz to 1000 MHz. The transducer 12 with the element 27 according to the invention for the reduction of turbulence 30 and wave formation in the coupling medium 8 can be used in a wide variety of ultrasound microscopes.

The invention has been described with reference to a preferred embodiment. However, it will be apparent to those skilled in the art that modifications or changes may be made to the invention without departing from the scope of the following claims. It is obvious to a person skilled in the art that the turbulence-reducing element 27 can have modifications which likewise achieve the effect of the turbulences 30 are significantly reduced during the movement of the transducer 12 in the coupling medium 8.

Claims

Claims:

1 . Device for nondestructive inspection of the interior of components (2), in particular with an ultrasound assembly (10), with at least one transducer (12) associated with the component (2), between the component (2) and a free end (12a ) of the at least one transducer (12) a liquid coupling medium (8) is provided, that for the inspection of the entire component (2) a traversing device (9) is provided, the meandering the at least one transducer (12) substantially along a first direction of movement ( 20a) and along a second, the first direction of movement (20a) opposite direction of movement (20b) in the liquid coupling medium (8) on the component (2) moves, characterized in that the at least one transducer (12) in the direction of the first direction of movement (20a ) and in the direction of the second movement direction (20b) each have a during the movement in the liquid coupling medium (8) turbulence reducing projection (27a, 27b) is.

2. Device according to claim 1, wherein the extensions (27a, 27b) of the at least one transducer (12) have a height (H) and that when using the at least one transducer (12) the extensions (27a, 27b) at least half of Immerse height (H) in the liquid coupling medium (8).

3. A device according to any one of claims 1 and 2, wherein each of the extensions (27a, 27b) has a length (L) and a maximum width (B), the length (L) is greater than the maximum width (B) and that the maximum width (B) is at least equal to a diameter (D) of the at least one transducer (12) at the free end (12a) of the transducer (12).

4. Device according to one of claims 1 to 3, wherein each of the extensions (27a, 27b) has the same shape.

A device according to claim 4, wherein the shape is an isosceles triangle and the two legs (28) enclose an acute angle (cc) in the direction of movement (20a 20b) and form a rounded tip (29).

6. Transducer (12) for nondestructive inspection of the interior of components (2), wherein the transducer (12) has a free end (12 a) from which the ultrasonic waves can be emitted and an echo of the emitted ultrasonic waves can be received, characterized in that an element (27) which has two opposite extensions (27a, 27b) is fastened to the transducer (12).

7. Transducer according to claim 6, wherein the extensions (27a, 27b) of the element (12) have at least one height (H), a length (L) and a maximum width (B), wherein the length (L) is greater than the maximum width (B) and wherein the maximum width (B) is at least equal to a diameter (D) of the at least one transducer (12) at the free end (1 2a) of the transducer (12).

8. Transducer according to claims 6 to 7, wherein the element (27) with the two extensions (27a, 27b) is arranged on the transducer (12) such that the free end (12a) of the transducer (12) the element (27 ) surmounted.

A transducer according to claims 6 to 8, wherein each of the projections (27a, 27b) has the same shape.

10. Transducer according to claim 9, wherein the shape is an isosceles triangle and the two legs (28) form an acute angle (cc) and form a rounded tip (29).