FR3093185A1 - Ultrasonic testing device and method - Google Patents

Abstract

A device for transmitting ultrasonic monitoring of a wall (10) having two opposed surfaces (12, 14), said device comprising: an ultrasonic transmitter (16) adapted to emit an ultrasonic signal through said wall (10) when it is applied against one (12) of said opposing surfaces; an ultrasonic receiver (18) adapted to be applied against the other (14) of said opposite surfaces to the right of said transmitter (16) to receive said ultrasonic signal; and, a processor (54) for comparing the ultrasonic signal received by said receiver (18) with respect to a reference signal. Said transmitter (16) and said receiver (18) further comprise magnetic devices (24, 24 ') to be able to cause the attraction of said transmitter (16) and said receiver (18) through said wall (10), and of so as to be able to simultaneously drive said transmitter (16) and said receiver (18) in sliding movement respectively against said opposite surfaces (12, 14). Figure to be published with the abstract: Fig. 3

Description

Device and method of ultrasonic testing

The present invention relates to a device for ultrasonic inspection of a wall having two opposite surfaces.

A field of application envisaged is in particular, but not exclusively, that of the control of walls made of composite material.

Known ultrasonic inspection devices operating by reflection make it possible to detect defects in compactness or discontinuity present in particular in metal parts. The principle is to implement, thanks to an ultrasonic source applied against a surface of the part, a beam of ultrasonic waves through the part and to collect the ultrasonic signals reflected on the opposite surface of the part, at the level of said source, which this time plays the role of receiver. If the metal part contains a defect, a fraction of the ultrasonic energy will reflect off the defect and an additional signal will appear at the source.

These devices use as a source of ultrasonic vibrations a transducer, which comprises a piezoelectric ceramic element that provides a mechanical vibration when subjected to an electric current. Conversely, the ceramic element is able to provide an electrical signal in response to mechanical stress. In this way, the translator is not only able to generate ultrasonic vibration beams, but also to collect the reflected signals so that they can then be processed.

Other known ultrasonic control devices require the implementation of two identical translators, one playing the role of transmitter, the other the role of receiver. The transmitter is applied to one of the surfaces of the part, while the receiver is applied to the other surface coaxially in line with the transmitter. Usually, the transmitter and the receiver are respectively installed at the ends of the branches of a fork, so as to be maintained coaxially. Also, such a device makes it possible in particular to control the edges of the room.

The implementation of such ultrasonic control devices is then impossible to control the parts of parts remote from the edges and more generally the large structures.

Also, a problem which arises and which the present invention aims to solve is to provide an ultrasonic inspection device in transmission which makes it possible to easily inspect parts with a large surface area.

With the aim of solving this problem, it is proposed, according to a first object, an ultrasonic control device in transmission of a wall having two opposite surfaces, said device comprising:
- a portable ultrasonic transmitter adapted to emit an ultrasonic signal through said wall when it is applied against one of said opposite surfaces;
- a portable ultrasonic receiver adapted to be applied against the other of said surfaces opposite to the right of said transmitter to receive said ultrasonic signal; and,
- a processing unit for comparing the ultrasonic signal received by said receiver with a reference signal, and for evaluating the presence of a defect inside said wall as a function of the difference of the signals; said transmitter and said receiver further comprise magnetic devices to be able to cause the attraction of said transmitter and said receiver towards each other through said wall, while said transmitter and said receiver are mechanically free from each other another, and so as to be able to simultaneously drive said emitter and said receiver in sliding motion respectively against said opposite surfaces.

Thus, a characteristic of the invention lies in the implementation of the magnetic devices to be able to maintain the transmitter and the receiver coaxially thanks to the magnetic attraction forces which are exerted between the two through the wall. In this way, there is no need to resort to a U-shaped mechanical element to maintain transmitter and receiver, one opposite the other, and moreover, the control device according to the invention can be put in works to control walls whose opposite surfaces are inaccessible with a fork whose branches are respectively equipped with a transmitter and a receiver. This is the case with the vessel walls, for example. The transmitter can thus be driven in translation against one of the walls, while the receiver, thanks to the magnetic attraction forces, is itself driven in translation against the other wall and remains in line with the transmitter. The control of the wall can thus be carried out by scanning the latter. Also, the control device according to the invention makes it possible to detect defects of compactness or discontinuity in non-magnetic materials, for example composite materials, and in particular the defects of wind turbine blades made of this type of material. As regards the reference signal, it is preferably an audible signal received from the receiver when the wall is defect-free.

Surprisingly, and contrary to what one might expect, the magnetic field induced by the magnetic devices does not disturb the ultrasonic signals passing through the wall.

According to a particularly advantageous embodiment of the invention, said magnetic devices comprise two permanent magnets mounted respectively on said generator and on said receiver. Thus, the transmitter has a first permanent magnet, while the receiver has a second permanent magnet. Each permanent magnet has a north magnetic pole and a south magnetic pole. Also, the permanent magnets of the receiver and the transmitter are oriented so that they attract each other through the wall, in other words, by orienting a south pole towards a north pole. Also, permanent neodymium magnets are implemented to achieve maximum attraction.

Also, according to a variant embodiment, the magnetic devices comprise two electromagnets. In particular, they make it possible to vary the intensity of the magnetic field according to the roughness of the surfaces of the wall and its thickness. The implementation of electromagnets can also solve a safety problem related to pinching or crushing.

According to another mode of implementation, the receiver and the transmitter respectively comprise a plurality of magnets. The plurality of magnets are adjusted so as to obtain a well-determined angular position of the transmitter and the receiver. For example, each plurality of magnets has three magnets.

Preferably, said permanent magnets have an annular shape. In this way, the two magnets of the receiver and the transmitter fit perfectly coaxially on either side of the wall. Furthermore, the two ring-shaped permanent magnets are identical, both in size and in their magnetic properties.

According to a particularly advantageous embodiment of the invention, said transmitter comprises an ultrasonic translator operating in transmission. Thus, the ultrasonic transducer operating in transmission comprises a piezoelectric ceramic element suitable for converting an electric signal into an ultrasonic wave.

Advantageously, said ultrasonic transducer operating in emission is installed coaxially inside one of said ring-shaped permanent magnets. Thus, the ultrasonic transducer, of cylindrical symmetry, is installed in the center of the ring-shaped permanent magnet, and it is able to generate a mechanical wave through the wall, which propagates along the axis of symmetry of the magnet. .

Preferably, said receiver comprises an ultrasonic translator operating in reception. Also, the ultrasonic transducer operating in reception comprises a piezoelectric ceramic element which allows the conversion of an ultrasonic wave into an electrical signal.

Furthermore, said ultrasonic transducer operating in reception is preferably installed coaxially inside the other of said ring-shaped permanent magnets. In this way, the two ring-shaped permanent magnets fit in line with each other, on either side of the wall, coaxially, so that the ultrasonic transducer operating in reception extends coaxially with the ultrasonic transducer operating in emission on the other side of the wall. The movement of the ultrasonic transmitter against the surface simultaneously causes the movement of the ultrasonic receiver against the other surface thanks to the two permanent magnets. And in this way, the two ultrasonic translators remain coaxial.

According to a particular embodiment of the invention, said ultrasonic transducer is kept centered inside said annular-shaped permanent magnet by means of an annular centering ring. The centering ring is for example made of a polymer material.

According to a particularly advantageous embodiment of the invention, said transmitter and said receiver respectively have an application surface equipped with running gear. In this way, the frictional forces of the receiver and the transmitter against their respective opposite surfaces are reduced. Therefore, the receiver follows the movements of the transmitter without delay and the signals are not disturbed during the movement.

Preferably, the running gear comprises balls. These balls make it possible to further reduce the frictional resistance of the movement of the receiver and the transmitter on the corresponding surfaces.

According to another aspect, there is proposed a method of ultrasonic testing of a wall having two opposite surfaces by means of a device of the type described above. This method includes the following steps:
- Said emitter is applied against one of said opposite surfaces;
- Said receiver is applied against the other of said surfaces opposite to the right of said transmitter so that said transmitter and said receiver are attracted towards each other through said wall; and,
- said transmitter is driven in sliding motion against said one of said opposite surfaces, said receiver being simultaneously driven in sliding motion against the other of said opposite surfaces, while the ultrasonic signal received by said receiver is compared with a reference signal , in order to be able to evaluate the presence of a defect inside said wall as a function of the difference of the signals.
In this way, by driving the transmitter continuously against the surface, the receiver is itself driven parallel and simultaneously against the opposite surface. Hence, thanks to the processing unit, the ultrasound signal received is displayed on a display screen, and a defect in the wall is detected during scanning by examining the attenuation of the received signal with respect to the reference signal.
is a schematic perspective view from below of an element of the control device according to the invention;
is a schematic perspective view from above of the element represented in the figure [Fig.1];
is a schematic view in partial axial section of the control device according to the invention;
is a block diagram of the control device according to the invention; and,
is an implementation flowchart of the control device according to the invention.

The figure is a partial schematic view of a control device according to the invention implemented on either side of a wall made of non-magnetic material, and in this case of a composite material 10. This wall 10 has a first surface 12 opposite a second surface 14. The control device thus comprises a portable ultrasonic transmitter 16 applied to the first surface 12 of the wall 10 and facing it, a portable ultrasonic receiver 18 applied opposite to the second surface 14.

The portable ultrasonic transmitter 16 comprises a first support 20 and a first ultrasonic translator 22 adapted to operate in transmission. The first ultrasonic transducer 22 is of cylindrical symmetry of revolution and comes directly into contact with the first surface 12 of the wall 10. Furthermore, the ultrasonic transmitter 16 further comprises a first annular permanent magnet 24 extending around the first transducer 22 in the vicinity of the first surface 12.

The first support 20 comprises a first annular base 26 of axial symmetry of axis A and having a support face 25 opposite a free face 27. Also, the first support 20 comprises a first sleeve 28 having a low-cut end 30, fitted inside the annular base 26. The low-cut end 30 defines a shoulder and it is inserted inside the annular base 26 to a depth substantially equal to half the thickness of the annular base 26. so, the necked end 30 and the annular base 26 together define an annular space 34 inside which is housed the first annular permanent magnet 24. Also, the annular base 26 has an internal flange 35 extending in the extension of the bearing surface 25 and allowing the first annular permanent magnet 24 to be held in engagement between the turned end 30 and precisely the internal collar 35. This internal collar 35 has a thickness minimum force to obtain a maximum magnetic attraction force of the annular permanent magnet 24, as will be explained below.

The annular base 26 further comprises adjustable support elements 36 making it possible to facilitate the movement of the ultrasonic transmitter 16 to the first surface 12 of the wall 10 as will be explained below.

Thus, the adjustable support elements 36 are mounted axially in the thickness of the annular base 26. They comprise a pad 38 in which is imprisoned a ball 40 capable of coming to extend substantially projecting from the support face. 25 of the first annular base 26. Also, the shoe 38 is connected to a screw 42 passing through a nut 44 secured to the free face of the first annular base 26 so as to be able to adjust the axial position of the shoe 38.

Also, we will refer to the figures and [Fig.2] illustrating in perspective respectively in bottom view and in top view the first support 20. It will be observed in the figure [Fig.1] that the first annular base 26 has an octagonal outer shape and that the pads 38 equipped with their ball 40 are regularly distributed around the first annular permanent magnet 24. The figure [Fig.2] illustrates the opposite, the screws 42 extending through the nuts 44 and projecting from the free face 27 of the base 26. There is also the first sleeve 28.

Thus, thanks to the eight screws 42, the axial position of the pads 38 is adjusted in the thickness of the first octagonal annular base 26, so that their balls 40 extend substantially projecting from the bearing face 25 and come tangent to the same plane substantially parallel to the bearing face 25.

In addition, we see in Fig. that the first sleeve 28 has a radial orifice 46 making it possible to maintain the first ultrasonic transducer 22 in the axial position.

With regard more specifically to the first ultrasonic transducer 22, illustrated in FIG. 3, it comprises a first cylindrical casing of revolution 48 having a first active end 50, forming a sole, opposite a first free end 52. The cylindrical casing of revolution 48 is equipped, inside at the level of the active end 50, with a piezoelectric element, not shown. The cylindrical casing is then engaged inside the sleeve 28 so that the active end 50 can come into contact against the first surface 12 of the wall 10. Also, the cylindrical casing 48 is held in a fixed position with respect to to the sleeve 28 by means of a screw, not shown, engaged in the radial orifice 46 which is shown exclusively in the figure .

According to another mode of implementation, not shown, the cylindrical casing of the ultrasonic transducer is slidably mounted inside the sleeve and it is connected thereto by means of a return spring so that the active end forming sole remains in permanent contact with the first surface during the movement of the transmitter on the surface. This mode of implementation is particularly suitable when the surface to be checked is not perfectly flat.

Also, it will be observed that the first ultrasonic transducer 22 is then installed inside the first sleeve 28 so that its active end 50 comes flush with the mean plane coming tangent to the balls 40 of the pads 38.

On the other hand, the first annular permanent magnet 24 is installed in the annular space 34 in engagement between the necked end 30 of the first sleeve of revolution 48 and the collar 35 so as to be kept substantially set back from the bearing face 25 of the first octagonal annular base 26. Therefore, the first annular permanent magnet 24 does not come into direct contact with the first surface 12.

As regards the portable ultrasonic receiver 18, applied to the second surface 14 of the wall 10, it comprises a second support 20' identical in all respects to the first support 20. The second support 20' comprises a second octagonal annular base 26' of axial symmetry and having a second bearing face 25' opposite a second free face 27'. Also, the second support 20' comprises a second sleeve 28' having a second low-cut end 30' fitted inside the second octagonal annular base 26'.

On the other hand, the ultrasonic receiver 18 comprises a second ultrasonic translator 22′ adapted to operate, itself, in reception. This second ultrasonic transducer 22', of cylindrical symmetry of revolution, comes directly into contact with the second surface 14 of the wall 10. Furthermore, the ultrasonic receiver 18 further comprises a second annular permanent magnet 24' extending around the second translator 22' installed in the second annular space 34' engaged between the second necked end 30' of the second sleeve of revolution 28' and the second collar 35'. In this way, the second annular permanent magnet 24' is kept substantially set back from the second bearing surface 25' of the second octagonal annular base 26'.

Furthermore, the two annular permanent magnets 24, 24' are oriented, as regards their polarity, in opposite directions with respect to their support 20, 20', so as to be able to attract each other when the ultrasonic transmitter 16 and ultrasonic receiver 18 are fitted on either side of wall 10 as shown in Figure 3.

The second octagonal annular base 26' is equipped with second adjustable support elements 36' mounted axially in the thickness of the second octagonal annular base 26'. They comprise a second shoe 38' in which is imprisoned a second ball 40' capable of coming to extend substantially projecting from the second bearing face 25'. Also, the second pad 38' is connected to a second screw 42' passing through a second nut 44' integral with the second free face of the second octagonal annular base 26' so as to be able to adjust the axial position of the second pad 38'.

As for the second ultrasonic transducer 22', it comprises a second cylindrical housing of revolution 48' having a second active end 50' opposite a second free end 52'. The second cylindrical housing of revolution 48' is equipped, inside at the level of the second active end 50', with a piezoelectric element, not shown. The cylindrical casing is then engaged inside the second sleeve 28' so that the active end 50' can come into contact against the second surface 14 of the wall 10. Also, the second cylindrical casing 48' is held in a fixed position with respect to the second sleeve 28' thanks to a screw, not shown, in a manner analogous to the first cylindrical casing 48.

Also, it will be observed that the second ultrasonic translator 22' is then installed inside the second sleeve 28' so that its active end 50' comes flush with the mean plane coming tangent to the second balls 40' of the second pads 38' .

Also, the two annular permanent magnets 24, 24' are neodymium magnets, powerful enough for the transmitter 16 and the receiver 18 to be able to exert forces on each other allowing them, not only to maintain themselves in position fixed respectively against the first 12 and second 14 surfaces when they are at rest, while the ultrasonic translators 22, 22' extend coaxially, but also, to remain in line with each other, when one or the other of the receiver 18 and the transmitter 16 is driven in translation. In other words, if the transmitter 16 is for example driven in translation against the first surface 12 of the wall 10, the receiver 18 will be driven in parallel in translation, and facing the transmitter 16, on the second surface 14. The translators ultrasound 22, 22' will remain coaxial.

We will now refer to Fig. showing the wall 10 in perspective, and schematically with respect to FIG. 3], the transmitter 16 and the receiver 18 facing each other, respectively applied against the first surface 12 and the second surface 14. Also, the transmitter 16 and the receiver 18 are connected to a control device 54, or ultrasonic station, respectively via a power supply cable 56 and a reception cable 58. The control device 54, or ultrasonic station, includes a processing unit and a display screen making it possible to visualize the ultrasonic signal detected by receiver 18.

Thus, in accordance with the control method according to the invention, and according to the flowchart of FIG. , in a first step 60, the transmitter 16 is applied against the first surface 12 then in a second consecutive step 62, the receiver 18 is applied against the second opposite surface 14, and this, in line with the transmitter 16 so as to that the transmitter 16 and the receiver 18 are attracted towards each other through the wall 10. Also, thanks to the control device 54, or ultrasonic station, the transmitter 16 is supplied and more particularly the first ultrasonic translator 22, for example at a frequency of 4 MHz, while the signal received by the second ultrasonic translator 22' is recorded on the other side. According to a third step 64, the transmitter 16 is driven in a sliding movement against the first surface 12, and the receiver 18 is then simultaneously driven in a sliding movement against the second opposite surface 14. This sliding movement is made easier, both that of the transmitter 16 than the receiver 18, thanks to the balls 40, 40'. Advantageously, a scrupulous scanning of the wall portion 10 to be checked is carried out.

Also, thanks to the processing unit, according to a fourth step 66, the ultrasonic signal received by the receiver 18 is compared with a reference signal, in order to be able to evaluate the presence of defects inside the wall 10 by depending on the signal difference. This reference signal is for example established in a wall portion that is known to be free of any defect, discontinuity or lack of compactness. Indeed, when the wall has an internal defect, by definition not visible from the outside, the ultrasonic wave which passes through it is significantly disturbed compared to a portion of the wall free of defect.

Claims (11)

Device for ultrasonic monitoring in transmission of a wall (10) having two opposite surfaces (12, 14), said device comprising:
- a portable ultrasonic transmitter (16) adapted to emit an ultrasonic signal through said wall (10) when it is applied against one (12) of said opposite surfaces;
- a portable ultrasonic receiver (18) adapted to be applied against the other (14) of said opposite surfaces in line with said transmitter (16) to receive said ultrasonic signal; and,
- a processing unit (54) for comparing the ultrasonic signal received by said receiver (18) with a reference signal, and for evaluating the presence of a defect inside said wall (10) as a function of the difference signals;
characterized in that said transmitter (16) and said receiver (18) further comprise magnetic devices (24, 24') to be able to cause said transmitter (16) and said receiver (18) to be attracted towards each other another through said wall (10), while said transmitter (16) and said receiver (18) are mechanically free from each other, and so as to be able to simultaneously drive said transmitter (16) and said receiver (18 ) in sliding motion respectively against said opposite surfaces (12, 14). Control device according to Claim 1, characterized in that the said magnetic devices (24, 24') comprise two permanent magnets mounted respectively on the said transmitter (16) and on the said receiver (18). Control device according to Claim 2, characterized in that the said permanent magnets (24, 24') have an annular shape. Control device according to any one of Claims 1 to 3, characterized in that the said transmitter (16) comprises an ultrasonic translator (22) operating in transmission. Control device according to Claims 3 and 4, characterized in that the said ultrasonic translator (22) operating in emission is installed coaxially inside one of the said permanent magnets (24) of annular shape. Control device according to any one of Claims 1 to 5, characterized in that the said receiver (18) comprises an ultrasonic translator (22') operating in reception. Control device according to Claims 3 and 6, characterized in that the said ultrasonic translator (22') operating in reception is installed coaxially inside the other of the said ring-shaped permanent magnets (24'). Control device according to Claims 5 or 7, characterized in that the said ultrasonic transducer (22, 22') is kept centered inside the said annular-shaped permanent magnet (24, 24') by means of a centering ring. annular. Control device according to any one of Claims 1 to 8, characterized in that the said transmitter (16) and the said receiver (18) respectively have an application surface equipped with rolling members (40, 40'). Control device according to Claim 9, characterized in that the said rolling members comprise balls (40, 40'). Method of ultrasonic testing in transmission of a wall (10) having two opposite surfaces (12, 14) by means of a device according to any one of Claims 1 to 10, characterized in that it comprises the following steps:
- said emitter (16) is applied against one (12) of said opposite surfaces;
- said receiver (18) is applied against the other (14) of said surfaces opposite to the right of said transmitter (16) so that said transmitter (16) and said receiver (18) are attracted towards each other through said wall; and,
- said transmitter (16) is driven in sliding motion against said one (12) of said opposing surfaces, said receiver (18) being simultaneously driven in sliding motion against the other (14) of said opposing surfaces, while the signal is compared ultrasound received by said receiver (18) with respect to a reference signal, in order to be able to assess the presence of a defect inside said wall (10) as a function of the difference of the signals.