FR3030046A3 - METHOD AND DEVICE FOR INSPECTING A LINK, IN PARTICULAR A SOLDERED OR GLUE LINK BETWEEN TWO MATERIALS - Google Patents

Abstract

The present invention relates to a method of inspecting a connection between two materials by waves emitted by an ultrasound element. The method comprises a step of injecting a viscous gel, except water, into a hollow column disposed between the connection to be inspected and the ultrasound element, so that the waves pass between the element and the connection to through the gel filling the hollow column. The present invention also relates to a sensor and an ultrasonic system for inspecting a connection between two materials. Application: automotive domain

Description

FIELD OF THE INVENTION The present invention relates to a method and a device for inspecting a connection between two materials, in particular a welded connection or a glued connection. It applies in particular, but not exclusively, to the field of the automobile. A general problem of welding assembly is to check the quality of the welded connections without altering them, as well as to check the health of the materials in the vicinity of these connections. A known solution is ultrasonic testing, especially in an industrial environment. But since ultrasound is poorly transmitted in the air, rather complex techniques must be deployed to perform this type of control. Indeed, a connection between two elements, whether of plastic elements or sheet metal, may not have a uniform surface to the right of the connection, as is the case for example on welded points of an automobile body: the electrodes deform the two assembly surfaces, this deformation being called "indentation". Thus, air pockets may appear between the connection to be inspected and the ultrasonic sensor, attenuating the wave transmission. This is a disadvantage that the present invention proposes to solve. In order to overcome this problem, US patent application 2007/0282546 A1 discloses an ultrasound control device having a water column closed at one of its two ends by an ultrasonic sensor and closed at its other end. by a deformable membrane. Water under pressure in the column preforms the membrane, so that it has a convex shape on its outer face to the water column. The convex face of the membrane is attached to a coupling gel and then brought into contact with the point to be inspected: the complex complex formed by the water column, the deformable membrane and the gel film constitute an adapting interface. indentations, that is to say preventing the appearance of air pockets between the sensor and the connection to inspect. A disadvantage of such a solution is that, in the case of welded spots, welding sparking at the moment may leave peaks of solidified material on the indentation edges. During the check, the operator must file these peaks to prevent them from piercing the membrane. In the case where the membrane bursts, the water in the column is emptied. The operator must then disassemble the sensor, that is to say the water column and its threaded ring, to change the membrane and fill the water column. Moreover, the detection of the peaks proves to be delicate and, even if a systematic filing operation is envisaged, this operation does not guarantee to preserve the membrane against aggressions of the sheet: it tends to wear out naturally by deformation under the pressure that is exerted on it so that it marries the surface of the connection to control. It is therefore necessary to regularly stop the industrial process to replace the membrane. This again is a disadvantage that the present invention proposes to solve.

The object of the invention is in particular to solve the aforementioned drawbacks, so that it is no longer necessary to interrupt the inspection process regularly. To this end, the subject of the invention is a method of inspecting a connection between two materials by waves emitted by an ultrasound element. The method comprises a step of injecting a viscous gel, except water, into a hollow column disposed between the connection to be inspected and the ultrasound element, so that the waves pass between the element and the connection to through the gel filling the hollow column.

In one embodiment where the connection to be inspected may be a substantially point-to-point connection and where the injection step may be preceded by a step of placing the ultrasound element and the hollow column opposite said connection. , the injection step can advantageously be completed when the viscous gel (141) overflows out of the hollow column in contact with the connection to be inspected. The injection step can then be followed by a wave emission step by the ultrasound element to the connection to be inspected through the gel in the hollow column and a reception step by the ultrasound element. echoes of said waves on the element to be inspected through the gel in the hollow column.

The injection step may moreover be completed when the point link to be inspected is entirely covered by gel having overflowed from the hollow column. In another embodiment in which the connection to be inspected may be a substantially linear link and where the injection step may be preceded by a step of placing the ultrasound element and the hollow column opposite a portion of said bond, the injection step may advantageously be followed, since the viscous gel overflows out of the column in contact with the bond to be inspected, by a step of scanning the linear bond, the injection step that can continue simultaneously. The injection and scanning steps can then be completed simultaneously, once the inspection is complete.

The present invention also relates to an ultrasonic sensor for inspecting a bond between two materials. The sensor comprises a hollow column open at each of its two ends and an ultrasonic element integrally disposed at one of the two ends of the hollow column, so as to emit waves through said column. The column comprises at least one orifice, in addition to its two ends, for injecting a viscous gel into the hollow column. The present invention further relates to an ultrasonic system for inspecting a bond between two materials. The system comprises at least one tray capable of containing a viscous gel, an ultrasonic sensor as described above, at least one pump capable of taking gel from the tank and injecting it into the injection orifice in the hollow column. said sensor, as well as at least one pump driving device, including hardware and software means for adjusting the flow rate and the amount of gel injected into the column.

The main advantage of the present invention is that it allows complete automation of the control, without requiring any operator to hold the sensor.

Other features and advantages of the invention will be apparent from the following description given with reference to the accompanying drawings which show: FIG. 1, by an architecture diagram, an embodiment of a system according to the invention for controlling the quality of a welded connection; FIGS. 2a, 2b, 2c and 2d, by schematic views of profile and from above, an example of a sensor and implementation of a method according to the invention; Figures 3a and 3b, by schematic views of profile and from above, alternative embodiments of a method according to the invention; FIGS. 4a, 4b and 4c, by schematic views from above, other examples of sensors according to the invention; FIGS. 5a and 5b, by architecture diagrams, of other exemplary embodiments of systems according to the invention; FIGS. 6a and 6b, by schematic views of profile and from above, still other alternative embodiments of a method according to the invention, particularly suitable for dynamic inspection; FIGS. 7a, 7b, 8a and 8b, by schematic views of profile and from above, still other examples of sensors according to the invention, particularly adapted to dynamic inspection.

FIG. 1 illustrates an exemplary embodiment of a system 1 according to the invention for controlling the quality of a welded connection LS of a car body. Unless otherwise stated in the remainder of the present application, it will be assumed that the link LS is a soldered point, that is to say a point link. The exemplary embodiment includes an electronic control device 3030046 5 11. The device 11 makes it possible in particular to drive a pumping device 12 for pumping a viscous coupling gel 141 contained in two tanks 14, via a three-way valve 16, in order to inject it into a hollow cylindrical column. 151 of height H and of diameter D, this column itself forming part of an ultrasonic sensor 15, via an injection orifice 1511. For the purposes of the present invention, the term "hollow column" must be understood to mean any structural element hollow capable of containing a liquid, whatever its shape and the material of which it is made. Disposed by one of its two open ends opposite the link LS 10 to be controlled, the column 151 is thus filled with gel 141 until the gel 141 overflows out of the column 151, as will be explained in more detail in FIG. following the present application. The ultrasonic sensor 15 further comprises an ultrasonic element 152 disposed at the other end of the two ends of the column 151. It may be for example a piezoelectric element.

Controlled by the device 11, the ultrasound element 152 is arranged to emit ultrasonic waves on the link LS and to receive their echoes through the column 151 filled with the viscous gel 141. In the present embodiment, the The column is cylindrical, but any other form of column capable of conveying ultrasonic waves and their echoes could be suitable without departing from the principles of the present invention. Once the control is completed, the device 11 can record the results of the control in a database 16. In an industrial environment, the system 1 can then move to another welded connection, not shown in FIG. 1: the sensor 15 can advantageously be moved automatically over this other link to be controlled. The system 1 can be equipped with a single or two coupling gel tanks, the presence of two bins advantageously allowing maintenance personnel to switch the gel sample from one tray to another and thus change a tray empty without having to stop the industrial control process. FIG. 2a illustrates, by a profile view surmounting a view from above, the sensor 15 according to the invention before being placed in position opposite the link LS and before filling the column 151. In the present example 3030046 6 embodiment , the sensor 15 has a cylindrical shape, however other forms can be envisaged depending on the shape of the connection to inspect.

FIG. 2b illustrates, again by a profile view surmounting a view from above, the sensor 15 according to the invention placed in position opposite the link LS and during the filling of the column 151.

FIG. 2c illustrates, again with a profile view surmounting a view from above, the sensor 15 according to the invention placed in position opposite the link LS with the column 151 filled to the point of overflow. The gel injection is interrupted as soon as it overflows out of the column 151, so that a gel ring is formed on the link LS when the column 151 is placed opposite the link LS, by compression on the link LS of the gel volume having effectively overflowed out of the column 151. Of this volume of gel having effectively overflowed out of the column 151 depends the diameter of the ring formed by compression on the link LS. It is in this configuration that the ultrasound element 152 can carry out the actual control, that is, transmit the waves on the link LS and receive their echoes. Indeed, it is in this configuration only that there is more air between the element 152 and the LS link, and the waves can be transmitted efficiently.

FIG. 2d illustrates, again by a profile view surmounting a view from above, the sensor 15 according to the invention after the end of the control, the sensor 15 having been set back from the link LS in order to be moved towards Another link to be controlled, not shown in the figure. The gel 141 does not have the same acoustic characteristics as water. However, the Applicant has been able to verify that the differences have no significant effect on the reliability of the measurements, which make it possible to detect the presence of inclusions or sinkholes. Indeed, measurements with a membrane sensor according to the prior art, namely a General Electric brand sensor (trademark) piezoelectric mono-element of 4 millimeters in diameter with a column and a hard membrane, have been carried out once with his column filled with water and another time with his column filled with coupling gel. These measurements show similar echograms on 3 different supports: a ceramic wedge, a welded point on corrugated steel sheets and a welded point on non-compliant steel sheets.

Depending on the H / D ratio, the viscosity of the gel 141 will have to be adjusted, in particular so that the gel 141 is sufficiently viscous so that it does not flow from the column 151 between two controls, that is to say when the lower part of the sensor 15 is free, as illustrated by FIGS. 2b and 2d. The optimum viscosity varies from sensor to sensor depending on the shape of its column, including its dimensions in the horizontal plane. Advantageously, the viscosity can be easily adapted by using a water-soluble gel initially having a very high viscosity. It is then sufficient to dilute it with more or less water to reduce its viscosity and adapt it to the shape of the column. Manufacturers such as SOFRANEL and General Electric (registered trademarks) offer this type of gel in their catalogs. It should be noted that a gel injection 141 by the single injection port 1511 constitutes an asymmetrical injection into the column 151. This asymmetry could result in a bad distribution of the gel 141 on the surface of the link LS to be controlled. With a low or medium pressure injection of the gel 141 into the orifice 1511, the downward thrust of said gel will be more on the side of the injection port 1511, with the risk illustrated by FIG. 3a: the risk to run out of gel on the surface of the LS link to be controlled, on the opposite side to the injection orifice 1511. Conversely, with a high pressure injection of the gel 141 into the orifice 1511, the gel is projected horizontally opposite the injection port 1511, and the downward thrust of said gel is more on the opposite side to the injection port, with the risk illustrated by FIG. 3b: the risk to run out of gel on the surface of the link LS to be checked, on the side of the injection orifice 1511. If the injection pressure of the gel 141 has an impact on its distribution on the surface of the link LS to be controlled , the risk of running out of gel in some places also depends on other factors such as the viscosity of the gel 141, the space between the sensor 15 of the LS link to control, or the H / D ratio. The higher the H / D ratio, the less the asymmetry has an impact on the distribution of the gel 141 on the surface of the LS link. The value D depends on the sensor used and therefore the characteristics of the link to be controlled, while the height H must logically remain relatively constant from one sensor to the other, not only to ensure the delay line function, but also for reasons of height congestion of the sensor. Thus, in order to limit the risk of poor distribution of the gel 141 on the surface of the link LS to be tested, several injection orifices may also be provided, as illustrated by FIGS. 4a, 4b and 4c which illustrate sensors 41, 42 and 43 respectively, having 2, 3 and 4 injection ports respectively, arranged symmetrically around the sensor. If the distribution of the injection orifices is relatively simple on a circular section sensor, it will be more complex on a non-cylindrical section sensor. In general, the determination of the number and the position of the gel injection orifices in the column will have to be the subject of a rheological study. With sensors with several gel injection orifices, such as the sensors 41, 42 and 43, it is possible to act in addition on another factor to control the homogeneous distribution of the gel on the surface of the connection to be controlled: the differences in speed and gel outlet pressure at each injection port. For this purpose, several architectures are possible, as illustrated by Figures 5a and 5b.

For example, as illustrated by FIG. 5a in the case of the sensor 41, each of the two injection orifices 4111 and 4112 can be associated with a dedicated pump for regulating the flow of the gel, namely a pump 421 and a pump. 422 respectively: each of the two pumps 3030046 9 421 and 422 draws gel 141 in one of the tanks 14, an electronic device not shown in the figure controlling the flow rate of the pumps 421 and 422 to obtain the expected speeds and gel pressures 141 at each of the two injection points 4111 and 4112.

For example, as illustrated in FIG. 5b, a single pump 52 may be driven by an electronic device not shown in the figure, with separation of the gel 141 at its outlet in two flows: one flow for each of the injection orifices 4111 and 4112. The speed and pressure at each of the injection ports 4111 and 4112 can be managed by means of flow regulators 171 and 172 positioned on each injection line.

The dynamic control of a link is understood as a scanning or a displacement of a sensor opposite the link, for example in the case where the sensor does not cover the entire link. This type of scanning can for example be envisaged on continuous linear links 20 or assimilated as such, such as for example a bead of glue or a weld bead. FIGS. 6a and 6b illustrate the sensor 15 sweeping the welded connection LS, which is here not a specific connection but a linear connection, FIG. 6a in the case of an injection of the low-pressure gel 141 in FIG. orifice 1511 and FIG. 6b in the case of an injection of the gel 141 at higher pressure in the orifice 1511. Compared with FIGS. 3a and 3b respectively, which illustrate the static inspection of the welded connection LS in the the same conditions of injection of the gel 141 as FIGS. 6a and 6b respectively, it is noted that the gel 141 is not distributed in the same way on the surface of the link LS according to whether there is displacement of the sensor 15 This is mainly due to the adhesion of the gel 141 to the LS bond to be controlled, as well as to the viscosity of the gel 141 itself. The levers for controlling the distribution of the gel 141 on the surface of the LS link to be controlled are generally the same as in the case of the static control, namely the number and the distribution of the injection ports of the gel 141, the pressure management potentially differentiated between 3030046 10 different injection or the choice of architecture according to Figure 5a or 5b. A difference however lies in the choice of the control parameters, which must take into account the displacement of the sensor 15, in particular its direction and its speed of displacement, as well as the fact that the gel injection 141 is done continuously on the entire duration of the scan. Two additional parameters can be used to control the distribution of the gel 141 on the surface of the LS link to be controlled, in particular to orient the exit of the gel 141 at the end of the column 151 towards the front of the sensor 15 relative to its direction. of displacement.

First of all, it is possible to act on the height of the injection orifice (s) of the gel 141 in the column 151, as illustrated by FIGS. 7a and 7b which, by comparing them with FIGS. 2a and 6b which respectively illustrate the height A of the injection orifice 1511 of the preceding figures and a dynamic control, to understand the effect of the height of the injection orifice. Indeed, Figures 7a and 7b illustrate an embodiment of a sensor 15 'comprising an ultrasonic element 152' and a column 151 ', the height A' of a single injection port 1511 'being strictly less than A By comparing FIG. 7b to FIG. 6b, it can clearly be seen that reducing the height of the injection orifice in the column makes it possible to orient the gel 141 better towards the front of the sensor relative to its direction of movement. Then, as illustrated by FIGS. 8a and 8b, it is possible to act on the inclination of the injection orifice, so as to send the gel not only towards the front of the sensor but also towards the bottom of the column, intensifying 25 the asymmetry, but ensuring that there is always enough gel towards the front of the sensor, between the latter and the LS link to control. Indeed, FIGS. 8a and 8b illustrate an exemplary embodiment of a sensor 15 "comprising an ultrasound element 152" and a column 151 ", the height A" of a single injection orifice 1511 "being equal to A ' but the orifice 1511 "being inclined at an angle p. in relation to the horizontal plane. Comparing FIG. 8b to FIG. 7b, it can clearly be seen that tilting down the injection orifice makes it possible to orient the gel 141 even further towards the front of the sensor relative to its direction of movement.

As previously explained, the main advantage of the present invention is its easy maintainability, without occasional change of membrane or filling of a water column. But the invention described above still has the advantage that its implementation is simple and inexpensive: pumps and valves for dispensing the gel are simple and reliable devices, the gel itself is a consumable customary field of the welding. In addition, it is possible to determine at industrial sites by simple successive tests the effective viscosity of the gel for a given sensor, depending on the diameter of its column in particular, without having to carry out theoretical calculations beforehand. Indeed, the optimal gel-water mixture to have the right viscosity is achievable very simply, from a single viscous gel. A single gel reference is therefore sufficient. Finally, in the case of a double tray of gel, it is possible to fill the tanks without stopping the production line. The present invention finds a particularly advantageous application on the production lines of automobile bodies, but it is also applicable to any field in which dots or cords gluing or welding are implemented: boiler, aeronautical, naval, furniture , rail, household appliances, etc.

Claims (8)

REVENDICATIONS1. A method for inspecting a bond (LS) between two materials by waves emitted by an ultrasound element (152), characterized in that it comprises a step of injecting a viscous gel (141), except for the water, in a hollow column (151) disposed between the connection to be inspected and the ultrasonic element, so that the waves pass between the element and the bond through the gel filling the hollow column. 2. Method according to claim 1, characterized in that the link (LS) to be inspected being a substantially point-specific connection and the injection step being preceded by a step of placing the ultrasound element (152). and the hollow column (151) facing said connection, the injection step is completed when the viscous gel (141) protrudes out of the hollow column in contact with the connection to be inspected. 3. Method according to claim 2, characterized in that the injection step is followed by: a wave emission step by the ultrasound element (152) to the link (LS) to be inspected through the gel (141) in the hollow column (151), and; a step of receiving by the ultrasound element echoes of said waves on the element to be inspected through the gel in the hollow column. 4. Method according to claim 2, characterized in that the injection step is completed when the point link (LS) to be inspected is entirely covered by gel (141) having overflowed the hollow column (151). 5. Method according to claim 1, characterized in that, the connection (LS) to be inspected being a substantially linear connection and the injection step being preceded by a step of placing the ultrasound element (152). and the hollow column (151) facing a part of said connection, the injection step is followed, as soon as the viscous gel (141) overflows out of the column in contact with the connection to be inspected, by a step of scanning the linear link, the injection step continuing simultaneously. 6. A method according to claim 5, characterized in that the injection and scanning steps terminate simultaneously, as soon as the inspection is complete. An ultrasonic sensor (15) for inspecting a link (LS) between two materials, the sensor comprising: a hollow column (151) open at each of its two ends; an ultrasound element (152) integrally disposed at one end of the hollow column for emitting waves through said column; The sensor being characterized in that the column comprises at least one orifice (1511), in addition to its two ends, for injecting a viscous gel (141) into the hollow column. 8. Ultrasonic system (1) for inspecting a link (LS) between two materials, the system being characterized in that it comprises: at least one tray (14) adapted to contain a viscous gel (141); an ultrasonic sensor (15) according to the preceding claim; at least one pump (12) capable of taking gel from the tank and injecting it into the injection port in the hollow column of said sensor; at least one device (11) for controlling the pump, including hardware and software means for adjusting the flow rate and the amount of gel injected into the column.