Probe holder device for automated ultrasonic testing

Abstract

The invention relates to a probe holder adapted to carry an ultrasonic probe for carrying out an ultrasonic inspection of a part to be inspected, the probe holder (100, 200) comprising a lower part (102, 202) and an upper part (101, 201), the lower part being configured to carry the ultrasonic probe and the upper part comprising a connection interface (110) configured for connecting the probe holder, according to a complete connection of the connection interface, to an effector capable of moving the probe holder in space in programmed positions, and comprising compliances in the upper and lower parts.

Description

Title of the invention: Probe-holding device for automated ultrasonic testing Technical field

[0001] The invention belongs to the field of non-destructive testing.

[0002] More particularly, but not exclusively, the invention belongs to the field of ultrasonic testing of complex composite parts of large dimensions, particularly in the aeronautical field, such as stiffened panels or spars. Prior art

[0003] Non-destructive testing of a composite material structure can be carried out by ultrasound. This technique makes it possible, in particular, to detect and quantify defects that are not visible from the surface of the part.

[0004] By way of non-limiting example, the defects that can be detected and quantified in terms of extent are delaminations, the presence of porosities, resin shortages or drying or fiber breaks, including in thick parts.

[0005] The automation of this control, where an ultrasonic probe is moved by a robotic device, makes it possible, by knowing the precise position of the probe relative to the part, to obtain a map of the material health, after computer processing of the information received from the ultrasonic probe and thus, in particular, to precisely locate these defects.

[0006] The ultrasonic probe, remote from the inspected part, comprises at least one emitter, most often in the form of a piezoelectric element which in an emitter configuration is capable of generating a mechanical stress in a frequency range of the order of one megahertz (106 s1) acting on an external surface of the part, thus generating a wave which propagates in the part.

[0007] Each defect encountered in the structure of the part generates reflections and diffusions of this wave. Thus, by capturing the signal modified by its propagation in the part, either by means of another piezoelectric element or the same piezoelectric element but configured as a sensor, it is possible, knowing the modes of propagation, reflection and diffusion of the ultrasonic waves in the material constituting the part subject to inspection, to draw up a map of the heterogeneities and more particularly of the defects present in the part in importance, extent and location.

[0008] Ultrasonic testing techniques are known to those skilled in the art and are particularly described in their principles with regard to composite materials. for example in the document “Ultrasonic C-Scan inspection of composite materials” A. Fahr et al. Engineering Journal of Qatar University, Vol. 5 1992, pp 201-222.

[0009] In order for the acoustic pressure generated by the piezoelectric element acting as a transmitter to be transmitted into the inspected material and not simply reflected by the surface of the part, a coupling means between the transmitter and the surface of the part is necessary. The same applies to the element used as a sensor. This coupling achieves, as it were, an acoustic impedance matching between the face of the piezoelectric element and the surface of the part.

[0010] Thus, a coupling layer is interposed between a piezoelectric element, acting as an emitter or sensor, and the surface of the part. According to the prior art, this coupling layer is generally in the form of a liquid or gel.

[0011] According to examples of implementation, the acoustic coupling layer is produced by immersing the part, by a jet of water between the part and the sensor, by a gel either deposited directly on the part or included in a shoe attached to the piezoelectric element optionally comprising a film of water between the part and the piezoelectric element or its shoe, without these examples being limiting.

[0012] Whatever the coupling technology, the realization of reliable measurements requires that the distance between the piezoelectric element and the surface of the part, that is to say the thickness of the coupling layer, be kept within a relatively tight tolerance, of the order of ± 0.5 mm, as well as the orientation of the probe relative to the surface of the part, which in general must be contained within a range of ± 2°.

[0013] For automated control where the probe is moved by robotic means relative to the part, the programming of the trajectories imposed by the robot on the probe is carried out from a CAD file of the part.

[0014] However, the actual part, while dimensionally correct, may deviate significantly from the shapes defined in the CAD file.

[0015] Furthermore, the positioning of the actual part in the robot space does not correspond perfectly to the positioning considered during the programming of the trajectories.

[0016] More particularly, on a part of complex shape and large dimension, these deviations, although small, are sufficient so that locally the position of the probe relative to the part and as programmed, deviates significantly from the positioning and orientation tolerances ensuring control under good conditions. Summary of the invention

[0017] The invention aims to resolve the drawbacks of the prior art and relates to this end to a probe holder adapted to carry an ultrasonic probe for carrying out an ultrasonic inspection of a part to be inspected, the probe holder comprising a part in lower and an upper portion, the lower portion being configured to carry the ultrasonic probe and the upper portion comprising a connection interface configured for connecting the probe holder, according to a complete connection of the connection interface, to an effector capable of moving the probe holder in space in programmed positions, wherein:

[0018] the upper part is linked to the connection interface by an upper compliance device configured to allow limited movement with an upper elastic return of the upper part relative to the connection interface along at least one translation axis;

[0019] the lower part is linked to the upper part by a lower compliance device configured to allow angular movements along at least two intersecting axes of rotation of the lower part relative to the upper part;

[0020] the lower part comprises at least two rolling elements (125) of diameter di and d2, the position of the ultrasonic probe being fixed relative to said rolling elements, which are configured to come into contact with the part to be controlled to define a distance and an orientation of the ultrasonic probe relative to at least one surface of the part to be controlled; and

[0021] characterized in that at least one of the secant axes of rotation is distant by a value respectively less than or equal to di and less than or equal to d2 relative to the axes of rotation of each of the at least two rolling elements.

[0022] Thus the probe holder makes it possible to keep the probe in a configuration of distance and orientation with respect to the surface of the part suitable for carrying out the inspection in good conditions even in the event of a difference between the programmed points of the effector and the actual position of the surface.

[0023] More particularly, the distribution of the translational and rotational compliances between the upper part and the lower part as well as the positioning as close as possible to the surface of the part to be controlled of at least one rotational compliance makes it possible to ensure the maintenance of a constant distance between the ultrasonic probe and the surface to be controlled independently of the deviations between the programmed points and trajectories and the actual position of the part to be controlled in the space of the effector.

[0024] The invention can be implemented according to the embodiments and variants set out below, which are to be considered individually or in any technically effective combination. Brief description of the drawings Fig.l

[0025] [Fig.l] shows in a perspective view a first example of the embodiment of a probe holder Fig.2

[0026] [Fig.2] shows in perspective a second example of embodiment of a probe holder; Fig.3

[0027] [Fig.3] shows figure 3A an example of the embodiment of the lower part of a carrier- probe for controlling a concave ray, figure 3B an example of the lower part of a probe holder for controlling a convex ray. Description of the embodiments

[0028] [Fig.l] according to an exemplary embodiment of the probe holder (100) adapted to the control of a stiffener, the latter comprises an upper part (101) and a lower part (102).

[0029] The upper part (101) comprises a connection interface (110) adapted for gripping the probe holder by an effector, for example an anthropomorphic robot or a gantry, and for ensuring a complete connection of the probe holder with this effector, for example by means of a clamp.

[0030] The lower part (102) carries an ultrasonic probe (150) adapted, in this example, to carry out an ultrasonic inspection on a face of a stiffener (191) extending substantially perpendicular to a skin (192), during a movement (195) of the probe holder relative to the part to be inspected (191, 192), this movement being carried out by means of the effector according to a programmed trajectory while the part to be inspected as well as at least the lower part (102) of the probe holder are immersed in a pool.

[0031] The ultrasonic probe is linked to the lower part (102) of the probe holder by a mechanism providing rotational compliances along at least two intersecting axes, which, according to this exemplary embodiment, comprise a first axis (121) substantially parallel to the face of the stiffener (191) and perpendicular to the skin (191), and a second axis (122) substantially parallel to the face of the stiffener (191) and parallel to the skin (191).

[0032] The skin (192) is here shown in place but may have one or two relatively high radius curvatures as in the case of a fuselage panel or wing of an aircraft.

[0033] The lower part also comprises 2 rollers (125) of diameter di=d2=d capable of rolling on the skin (192) during the control and thus ensuring the positioning relative to this skin of the ultrasound probe (150).

[0034] According to one embodiment (not shown) the lower part could comprise a pair of additional rollers bearing on the face of the stiffener (191) to be controlled, in this case the first rollers (125) would be replaced by balls capable of rolling on the surface of the skin.

[0035] These rolling elements, rollers and / or balls, define a position of the ultrasonic probe (150) in the lower part of the probe holder, and being in contact with at least one surface of the part to be checked, ensure precise positioning of the ultrasonic probe relative to the part.

[0036] The axes of rotation (121, 122) of the lower compliance are located as close as possible to the guide surfaces of the ultrasonic probe, i.e. the surfaces subject to ultrasonic testing and the surfaces with which the rolling elements are in contact. Thus, an axis of rotation is distant from the axis of a roller or the center of a ball by a distance equal to or less than d where d is the diameter of the rolling element.

[0037] The upper part (101) of the probe holder comprises an elastic compliance device connecting the lower part (102) of the probe holder to the connection interface (110). Said compliance device allows limited translational movement along at least one axis (111, 112). In the case of [Fig.l], the compliance device acts along two translation directions (111, 112).

[0038] [Fig.2] according to another exemplary embodiment suitable for controlling a flat panel or curved, the probe holder (200) comprises a connection interface (110), in an upper part (201), an ultrasonic probe (250) for controlling a surface of the panel, two rolling elements in the form of rollers (225) capable of rolling on the surface to be controlled of the panel and whose diameter is adapted to the curvatures thereof.

[0039] A lower part comprises compliances along two intersecting rotation axes (221, 222), located as close as possible to the surface to be controlled.

[0040] The upper part (201) comprises a translational compliance mechanism along an axis (212)

[0041] In the two embodiments [Fig.l] and [Fig.2] the angular movements around the compliance axes (121, 122, 221, 222) are of the order of ± 10°.

[0042] When inspecting a part, the lower part (102, 202) of the probe holder is immersed.

[0043] Advantageously, the upper part comprises one or more compliance indicators (141, 142, 242). These compliance indicators make it possible to visualize the position of the compliance devices according to the different compliance directions of the upper part and thus to visually check, during the execution of a trajectory corresponding to a movement program of an ultrasonic inspection, that these relative movements of the probe holder with respect to the connection interface remain within the limits of the movements authorized by these compliances and, consequently, that the ultrasonic probe remains in good contact with the surfaces of the part being inspected.

[0044] [Fig.3] shows different configuration of lower parts associated with a part upper as shown [Fig.l] for the control of different forms of surfaces to be controlled.

[0045] For example, figure 3A for control in a concave radius (301) comprising two sets of perpendicular rollers (325, 326) and 3 axes (321, 322, 323) of angular compliance.

[0046] Figure 3B for the control of a convex ray.

Claims

Claims

1. Probe holder adapted to carry an ultrasonic probe for carrying out an ultrasonic inspection of a part to be inspected, the probe holder (100, 200) comprising a lower part (102, 202) and an upper part (101, 201), the lower part being configured to carry the ultrasonic probe and the upper part comprising a connection interface (110) configured for the connection of the probe holder, according to a complete connection of the connection interface, to an effector capable of moving the probe holder in space in programmed positions, wherein: the upper part (101, 201) is linked to the connection interface (110) by an upper compliance device configured to allow limited movement with an upper elastic return of the upper part relative to the connection interface along at least one axis (111, 112, 212) of translation; the lower part (102, 202) is linked to the upper part by a lower compliance device configured to allow angular movements along at least two intersecting rotation axes (121, 122, 221, 222, 321, 322, 323) of the lower part relative to the upper part; the lower part comprises at least two rolling elements (125, 225, 325, 326) of diameter di and d2, the position of the ultrasonic probe being fixed relative to said rolling elements, which are configured to come into contact with the part to be controlled to define a distance and an orientation of the ultrasonic probe relative to at least one surface of the part to be controlled; and characterized in that at least one of the intersecting axes of rotation is distant by a value respectively less than or equal to di and less than or equal to d2 relative to the axes of rotation of each of the at least two rolling elements.

Images