SYSTEM AND METHOD FOR AUTOMATIC VERIFICATION OF THE RESPONSE OF A DEVELOPMENT FOR PERFORMING AN INTELLIGENCE PROCEDURE

Description

technical field

[0001] The present invention relates to non-destructive methods for verifying and sanctioning the conformity of dye penetrant testing chains.

[0002] Dye penetrant testing aims to detect cracks on the surface of a part in a non-destructive way by covering its surface with a penetrating, colored or fluorescent liquid, then observing the resurgence of the liquid from the cracks.

[0003] The present invention aims to constitute a system and its method for the validation of dye penetrant chains in a non-destructive and particularly repeatable manner, in which one guards against the variability of human analyses, and which allows the traceability of successive responses of the dye penetrant chains. Previous techniques

[0004] We know of methods for validating dye penetrant testing chains which consist of passing a standard piece (for example, "PSM-5P" or "PSM-SP-TAM" gauges) through the dye penetrant testing chain and deducing a penalty based on its response.

[0005] Current methods leave the responsibility for the sanction to an operator whose mission is to visually and qualitatively compare the calibration block coming out of the penetrant testing line with a reference image, which may possibly vary depending on his interpretation.

[0006] An approach aimed at controlling this process leads to periodic verification of the size of visible cracks in dye penetrant testing, which must not deviate.

[0007] This drift can be fixed, for example, at a threshold of thirty percent relative to the values ​​observed on a calibration block.

[0008] This validation step allows for the authorization of series production by dye penetrant testing.

[0009] In current methods, the human factor is therefore a potential source of variability, whereas the validation of the penetrant testing chain must be systematically respected to ensure process conformity and thus the quality of the penalties applied to the parts inspected using this method. This approach is crucial for series production.

[0010] Furthermore, the repeatability and accuracy of the operator's assessment can vary since they are based on a qualitative analysis made by the operator's eye.

[0011] Visual assessment does not allow for the archiving of all the data used to determine the calibration, which would enable traceability of the calibration process. This includes, for example, recording data such as numerical information, as the human eye cannot perform this function. Document EP 1 780 534 A1 discloses an automated system for validating the conformity of a penetrant testing chain's response by analyzing a cracked penetrant test specimen from said chain. This system comprises the cracked penetrant test specimen from said chain, a positioning base for the penetrant test specimen, an ultraviolet lighting device, and a camera with a lens directed at the positioning base. Description of the invention

[0012] The invention aims to overcome at least some of the aforementioned drawbacks and to propose a system for validating the response of a penetrant testing chain capable of combining the advantages of repeatability, stability and reliability for its implementation, while allowing traceability of the establishment of the sanction.

[0013] In view of the foregoing, the invention relates to an automatic validation system for the conformity of response of a penetrant testing chain by the digital analysis of a penetrant test specimen with cracks from said penetrant testing chain, said system comprising a housing surrounding all the elements of the system, a positioning base for the penetrant test specimen, at least two ultraviolet lighting devices positioned on either side of the positioning base so as to be able to illuminate it with ultraviolet light, an electronic board, a motorized linear guide controlled by the electronic board and adapted to be able to move and hold in position the positioning base in the housing, a monochrome camera having a lens directed towards the positioning base.

[0014] Preferably, said two ultraviolet lighting devices are inclined with respect to the vertical at an angle between fifty-four and sixty-six degrees.

[0015] For example, the camera is at a distance from the positioning base of less than twenty centimeters and the camera has a seventy-five millimeter lens coupled with an optical extension ring, adapted to provide an optical acquisition accuracy of less than ten micrometers.

[0016] Advantageously, the housing is equipped with a door and a door closure sensor coupled to the electronic board.

[0017] According to the invention, each lighting device comprises a light-emitting diode.

[0018] The invention also relates to a validation method for implementing a validation system as defined above, the method comprising the following steps: the placement on the positioning base of a penetrant standard piece having cracks and coming from said penetrant chain, the focused targeting of the camera on the cracks by the actuation of the motorized linear guide, the illumination of the cracks, the digital acquisition of an image of the cracks by means of the camera, the recording of said image, the measurement of the main dimensions of each crack, the dimensional comparison of the measurements to reference values, the validation of the response.

[0019] Advantageously, the duration of illumination of the cracks is approximately equal to the duration of acquisition of the image of the cracks; this makes it possible to avoid drifts due to heating of the lighting devices.

[0020] The method may further include a preliminary step in which the system is subjected to a reference calibration by monitoring and calibration using two different types of reference targets, one of which is a counterbored target adapted to calibrate the positioning provided by the positioning base and the accuracy of the measurements, and the other is a USAF1951 type target used to test intensity, dimension and area measurements.

[0021] Preferably, a preliminary step is planned, in which the system undergoes a reference calibration from a referencing carried out on the basis of an initial response from the penetrant chain.

[0022] The invention also relates to a method having a final step of archiving the image, measurements and the sanction. Brief description of the drawings

[0023] The invention will be better understood upon detailed study of an embodiment taken by way of non-limiting example and illustrated by the accompanying drawings, in which: [ Fig 1 ] represents a penetrant testing chain validation system according to the invention, in perspective view. Fig 2 ] represents the counterbored target in front view. Fig 3 [ ] represents a crack on the counterbored target in front view. ] Fig 4 ] represents the steps in the dye penetrant testing chain validation process. Detailed description

[0024] There Figure 1 illustrates system 1 of the invention, which allows automatic validation of the response conformity of a penetrant testing chain by the analysis of a penetrant test reference piece with cracks from said penetrant testing chain.

[0025] The system 1 comprises a housing 2, a positioning base 3 for the penetrating calibration piece 13, at least two lighting devices 4, an electronic card located in a computer station, a motorized linear guide 6 controlled by the electronic card and adapted to be able to move and hold in position the positioning base 3 in the housing 2, a monochrome camera 10 having a lens directed towards the positioning base 3.

[0026] A power supply 5 provides electrical power to the components, including the lighting device 4, the guide 6, and the electronic board.

[0027] A disconnect switch 9 can be provided to easily cut off the power supply and stop the process.

[0028] The housing 2 surrounds all the elements of system 1 so that they can be placed in darkness to protect observation from stray lighting.

[0029] Advantageously, the housing 2 is equipped with a door so that it can be opened and closed before and after each implementation of the process described below.

[0030] The housing 2 can be equipped with a door closure sensor 8 coupled to the electronic board to authorize or not the implementation of the process in case of a door closure failure.

[0031] The electronic card can be coupled to a computer allowing image processing, display and archiving of images from shots and responses.

[0032] The two lighting devices 4 are positioned on either side of the positioning base 3 and overhanging it so as to be able to illuminate it with downward lighting, which provides a localized, orientable and tiltable flux, with homogeneity on either side of the positioning base 3.

[0033] They illuminate with ultraviolet light, more specifically with an ultraviolet spectrum centered on the wavelength of three hundred and sixty-five nanometers for optimal response of the penetrant used for dye penetrant testing.

[0034] Each lighting device 4 includes a light-emitting diode, which makes the lighting operational instantly, avoiding warm-up time and providing a stable luminous flux, i.e., one whose power hardly varies over time.

[0035] Preferably, the two ultraviolet lighting devices 4 are inclined with respect to the vertical at an angle between fifty-four and sixty-six degrees.

[0036] This tilt of the spotlights defines the angle of light incidence on the positioning base 3 which gives the highest signal-to-noise ratio in the tested tilt range between thirty and seventy degrees.

[0037] It is necessary to have an angle of inclination greater than forty-five degrees.

[0038] The best positioning is achieved with an angle of inclination of around sixty degrees.

[0039] The camera 10 is preferably at a distance from the positioning base 3 of less than twenty centimeters and the camera 10 has a seventy-five millimeter lens 11 coupled with an optical extension ring, adapted to provide an optical acquisition accuracy of less than ten micrometers.

[0040] A 12 bandpass filter can be provided to further increase this acquisition accuracy.

[0041] As illustrated by the Figure 2, the penetrant calibration piece is for example covered with a counterbored target 13 which includes a body 14 having standard and / or normalized dimensions, and five holes 15 allowing the process to target five critical areas of the wedge containing indications which are decisive to the sanction of the penetrant chain.

[0042] System 1 will illuminate all areas, as illustrated by the Figure 2 , then analyze, measure and sanction these five zones of the calibration hold independently, for example with progress zone by zone.

[0043] As illustrated by the Figure 2 , the penetrant standard piece is for example a shim which has a body 14 having standard and / or normalized dimensions, and the process targets five critical areas of the shim containing indications which are decisive to the sanction of the penetrant chain.

[0044] System 1 illuminates all areas, as illustrated by the Figure 2, then analyzes, measures and sanctions autonomously these five zones 15 of the calibration hold, for example with a zone-by-zone advancement.

[0045] The wedge, for example, has 16 cracks such as those illustrated by the Figure 3 , constituting star-shaped indications for system 1.

[0046] The indications 16 are for example of decreasing diameters from top to bottom, with the dimension of the largest reaching up to six point three millimeters, and on average five millimeters in diameter for all the star cracks 16 before adding a positioning margin to this diameter.

[0047] Different gauge blocks with different dimensions can be used for the indications 16.

[0048] They are therefore unique and a reference must be made each time the cleat is changed.

[0049] For verification programs to be able to give a sanction after inspection, they must also be linked to requirements, which depend on the characteristics of the initial gauge block, the performance of the penetrant testing chain on the day of calibration, and the assessment of the level of penetrant testing after analysis of the penetrant block.

[0050] The implementation process is illustrated by the Figure 4 makes these steps particularly repeatable compared to known methods, thanks to the following steps: A first step E1 involves placing a test specimen with cracks 16, originating from the aforementioned penetrant testing chain, onto the positioning base 3; a step E2 involves focusing the camera 10 onto the cracks 16 by actuating the motorized linear guide 6; a step E3 involves illuminating the cracks 16; a step E4 involves digitally acquiring an image of the cracks 16 using the camera 10 and the electronic board; and a step E5 consists of: recording the image, measuring the principal dimensions of each crack 16, comparing the measurements to reference values, and validating the response. is being implemented.

[0051] Guide 6 is coupled with a calibration protocol for the positioning of the positioning base 3 in order to ensure the correct mechanical positioning of the PSM-5P wedge in system 1.

[0052] This calibration protocol is similar to traditional protocols used for industrial machines with mechanical movement, with the desired positioning accuracy corresponding to the regulatory requirements set.

[0053] Advantageously, the illumination time of cracks 16 in step E3 is substantially equal to the image acquisition time of cracks 16.

[0054] Indeed, a slight heating of the lighting systems 4 was observed, even though they include a light-emitting diode emitter which minimizes the heat emitted.

[0055] This heat shifts the frequency peak of the ultraviolet emission spectrum by a few nanometers over time, following a logarithmic trend.

[0056] It is important to note that this phenomenon remains imperceptible to the eye and difficult to detect unless a sufficiently sensitive device such as an image capture cell or an appropriate sensor is used.

[0057] As a result of this phenomenon, the fluorescence of the penetrant, sensitive to a wavelength centered at three hundred and sixty-five nanometers, becomes less intense despite the constant power of the illumination.

[0058] To overcome this effect, the lighting can be activated in stage E3 for a very short duration of "flash" type synchronized only with the duration of image acquisition, which avoids heating of the light-emitting diode emitter and keeps the wavelength at which the maximum energy value is emitted constant, thus giving an optimal and stable signal.

[0059] At step E4, image acquisition is optimized through a two-dimensional matrix analysis in which only the wedge installed on the positioning base 3 is observed in length and width.

[0060] Monochrome acquisition is done with a single color observed by a greyscale analysis, which improves the accuracy of the observations.

[0061] The 15 zones are on the order of ten millimeters by ten millimeters around each star 16 of the wedge, which requires a matrix of two thousand pixels by two thousand pixels.

[0062] The distance between the camera and the wedge is preferably less than twenty centimeters.

[0063] The acquisition accuracy is less than ten micrometers to properly quantify and sanction the fifth indication 16, namely the smallest, because its maximum diametrical dimension can go down to four hundred micrometers, even though on average it is generally about one millimeter in diameter.

[0064] To achieve an accuracy of ten micrometers or better, it is advantageous to sample on at least two pixels, which gives a resolution of five micrometers per pixel.

[0065] Sampling is optimal on four pixels, which gives a resolution of two and a half micrometers per pixel.

[0066] In regular use of the installation, system 1 aims to automatically confirm the sanction corresponding to a good level of response of the penetrant chain by comparing the analysis of a PSM-5P shim passed through the chain with that serving as the initial reference.

[0067] This initial reference was obtained with the same PSM-5P shim whose response was recorded during the initial validation of the chain for its commissioning based on a penetrant test response deemed satisfactory by the person responsible for the implementation of the installation.

[0068] Preferably, a preliminary step is implemented, in which system 1 is subjected to a reference calibration from a referencing carried out on the basis of an initial response from the penetrant chain.

[0069] The implementation process of system 1 may further include an upstream step in which system 1 is subjected to a reference calibration by monitoring and calibration using two reference targets of different types.

[0070] One of the two reference targets is a counterbored target 13 adapted to calibrate the positioning provided by the positioning base 3 and the accuracy of the measurements.

[0071] This counterbore target 13 allows verification of the correct mechanical positioning of the PSM-5P wedge in system 1 and the correct calibration of the measurement of the diameters of the circular indications 16 by means of an algorithm provided in the electronic board and under ultraviolet lighting.

[0072] The checks using the counterbore target 13 therefore make it possible to ensure the absence of drift in the mechanics and kinematics of system 1, but also an exact measurement of the stars 16 revealed in response to the penetrant, because the counterbore target 13 allows an adequate quantification of the star indications on the PSM-5P wedge regardless of their geometry and size, their signature varying according to the rather round shape without branches for the smallest star 16, and strongly marked branches for the first star, with a scale factor close to twenty between these two stars.

[0073] The other of the two reference targets is a USAF1951 type target ©< used to test intensity, size and area measurements.

[0074] Using this standard target as a resolution target allows for intensity calculation (signal / noise ratio) as well as the evaluation of the number of pixels, and verification ensures the stability of the calculated values.

[0075] Thanks to the two targets, we thus obtain a system 1 which makes it possible to avoid the possible intrinsic drifts of system 1, and this thanks, in addition, to a monitoring of the mechanical positioning of the wedges, a monitoring of the optical capture means, and a monitoring of the image processing algorithm and editing of the automatic sanction provided in the electronic card.

[0076] The general technical standard specifying the penetrant testing process allows thirty percent annual variability on the measurements of the diameter values ​​of the indications observed on a wedge, system 1 allowing this measurement to be carried out automatically on a daily basis.

[0077] System 1 has an intrinsic maximum variability of the order of two percent, that is to say of the order of measurement uncertainty, which is satisfactory to declare it capable.

[0078] The sanction of the response of the penetrant chain can be based solely on the diameter measurements of the stars 16 of the wedge, after thresholding on the grey levels, without necessarily having to take into account the histogram of the distribution of the grey levels or the number of pixels for the sanction of conformity of the response of the penetrant chain, and the histogram of the grey levels and the number of pixels can however continue to be monitored as an indication in order to allow control and control with more precision and responsiveness of possible drifts of the penetrant chain over time.

[0079] The process may include a final step of archiving the image, measurements and the sanction.

[0080] Unlike known methods, system 1 therefore allows the recording of images of the five zones as well as the values ​​of the inspection, which allows for total and reliable traceability, since it is digital.

Claims

1. System (1) for automatically validating the response compliance of a penetrant testing line by the numerical analysis of a reference test specimen with cracks undergoing dye penetrant testing coming from said penetrant testing line, said system (1) including said reference test specimen with cracks undergoing dye penetrant testing coming from said penetrant testing line, a casing (2) surrounding all the elements of the system (1), a positioning base (3) for the reference test specimen undergoing dye penetrant testing, at least two ultraviolet lighting devices (4) positioned on either side of the positioning base (3) so as to be able to illuminate it with ultraviolet light, an electronic board, a motorised linear guide (6) controlled by the electronic board and suitable for being able to move the positioning base and hold said positioning base (3) in position in the casing (2), and a monochrome camera (10) having a lens directed towards the positioning base (3), wherein each lighting device (4) includes a light-emitting diode.

2. System (1) according to claim 1, wherein said two ultraviolet lighting devices (4) are inclined with respect to the vertical by an angle of between fifty-four and sixty-six degrees.

3. System (1) according to either one of claims 1 and 2, wherein the camera (10) is preferentially at a distance from the positioning base (3) of less than twenty centimetres and the camera (10) has a lens (11) of sixty-five millimetres coupled with an optical extension ring, adapted to provide an optical acquisition precision of less than ten micrometres.

4. System (1) according to any one of the preceding claims, wherein the casing (2) is provided with a door and a door-closure sensor (8) coupled to the electronic card.

5. Method for validating the response compliance of a penetrant testing line for implementing a system according to any one of claims 1 to 4, including the following steps: - placing (E1) on the positioning base (3) a penetrant-testing reference test specimen including cracks (16) and coming from said penetrant testing line, - targeting (E2) the camera (10) in a focused manner on the cracks (16) by actuating the motorised linear guide (6), - illuminating (E3) the cracks (16), - digitally acquiring (E4) an image of the cracks (16) by means of the camera (10), - recording said image, - measuring the main dimensions of each crack (16), - dimensionally comparing the measurements with reference values, - sanctioning the response.

6. Method according to claim 5, wherein the duration of illumination of the cracks (16) is substantially equal to the duration of acquisition of the image of the cracks (16).

7. Method according to any one of claims 5 and 6, furthermore including a prior step in which the system (1) is the subject of a reference standardisation by monitoring and calibration using two reference test patterns of different types, one of which is a test pattern with countersinks (13) adapted to standardise the positioning provided by the positioning base (3) and the precision of the measurements, and the other is a test pattern of the USAF1951©) type used for testing intensity, dimension and surface measurements.

8. Method according to any one of claims 5 to 7, furthermore including a prior step in which the system (1) is the subject of reference standardisation using a referencing implemented on the basis of an initial response of the penetrant testing line.

9. Method according to any one of claims 5 to 8, furthermore including a final step of archiving the image, the measurements and the sanction.