Fluorescent penetrant detection method under white light condition

Abstract

The invention discloses a fluorescent penetrant detection method under a white light condition, and aims to solve the problems that when the ambient light illuminance is between 20Lx and 500Lx, a darkroom needs to be additionally built or lighting equipment needs to be added in the existing detection technology, and the correlation between parameters and sensitivity is fuzzy. The method comprises the following steps: firstly, establishing a white light illuminance-black light intensity-minimum recognizable defect size quantification correlation model, and then carrying out the steps of workpiece pretreatment, illuminance measurement and parameter initial determination, sensitivity test block verification, personnel qualification assessment, real-time parameter monitoring, remeasurement exception handling and the like. And accurate detection of the surface defects of the product in the illumination interval is realized. The method does not need additional equipment, quantifies the incidence relation between the detection parameters and the sensitivity, remarkably improves the detection efficiency and the result reliability, and is particularly suitable for scenes such as field operation and large-scale structure field detection.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing techniques, and more specifically, to a fluorescence penetrant testing method under white light conditions. Background Technology

[0002] Penetrant testing, as one of the five conventional non-destructive testing methods, plays an irreplaceable role in industrial production. According to relevant non-destructive testing standards, dye penetrant testing requires a minimum visible light illuminance of greater than 500 Lx on the surface of the workpiece being inspected, while fluorescent penetrant testing requires an ambient light illuminance of no more than 20 Lx. However, there are currently no applicable standards when the ambient light illuminance is between 20 Lx and 500 Lx.

[0003] To meet testing requirements, existing technologies require additional technical means to adjust lighting conditions: for example, using multi-point lighting equipment to increase illuminance to above 500 Lx for dye penetrant testing, or building a darkroom to reduce illuminance to below 20 Lx for fluorescence penetrant testing. However, in scenarios such as field operations and on-site inspection of large structures, the above-mentioned technical means suffer from problems such as inconvenient equipment portability, high setup costs, and low testing efficiency, and may even be impossible to implement due to site limitations.

[0004] Further analysis revealed that the core flaw in existing fluorescence penetrant testing methods lies in the lack of quantification regarding the correlation between detection parameters and sensitivity: it only vaguely mentions that defects can be clearly detected under a certain black light intensity, without clarifying the correspondence between black light intensity and the minimum identifiable defect size under different white light illuminance. This leads to the detection process relying on operator experience, highly random parameter settings, and difficulty in guaranteeing the repeatability and reliability of detection results, thus limiting the widespread application of this technology in standardized industrial testing scenarios. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies, such as fuzzy correlation between light and black light and sensitivity, poor environmental adaptability, and reliance on human experience. It provides a fluorescence penetration detection method under white light conditions, which achieves accurate and efficient detection in the 20Lx to 500Lx light range by establishing a quantitative correlation model and optimizing the detection process.

[0006] To achieve the above objectives, the present invention provides a fluorescence penetrant detection method under white light conditions, comprising the following steps: S1. When the ambient light intensity is between 20Lx and 500Lx, a quantitative correlation model between white light intensity and black light intensity is established to determine whether the yellow-green fluorescence generated by the fluorescent penetrant under a specific black light intensity can be effectively observed, thereby discovering product surface defects. S2, Pre-treatment of the surface of the workpiece to be inspected to remove oil, rust and coating impurities; S3. Using a white light illuminance meter, measure the ambient white light illuminance values ​​at various points on the workpiece surface and record the illuminance value corresponding to the point with the highest illuminance. ; S4. Determine the target detection sensitivity D based on the detection requirements, and calculate the minimum required black light intensity using the aforementioned correlation model. ; S5. Place a standard sensitivity test block of the same material as the workpiece at the point of highest illuminance. After operating according to the preset fluorescence penetrant testing standard, adjust the black light lamp power to ensure that the measured black light intensity is ≥ By observing the test block with a high-sensitivity CCD camera, if the defect corresponding to the target sensitivity can be clearly identified, the current situation can be determined. - For effective detection parameters; S6 performs formal inspection of the workpiece under effective detection parameter conditions, while simultaneously monitoring illuminance and black light intensity in real time. S7. After the test is completed, retest the parameters and process the test results according to the parameter deviation.

[0007] Furthermore, in step S1, the core formula of the association model is: ,in The smallest identifiable defect size, in mm. Black light intensity, measured in μW / cm² 2 , White light illuminance, measured in lux (Lx).

[0008] Furthermore, in step S2, the workpiece pretreatment adopts an ultrasonic cleaning combined with alcohol wiping process, wherein the ultrasonic cleaning power is 100-300W and the cleaning time is 5-30min, and the alcohol wiping uses industrial alcohol with a concentration of ≥95%.

[0009] Furthermore, in step S4, the standard sensitivity test block is the NACE standard test block, which contains artificial cracks of different widths from 0.05mm to 0.5mm; the high-sensitivity CCD camera has a resolution of ≥12 million pixels and is equipped with a 520-560nm yellow-green fluorescent filter.

[0010] Furthermore, in step S4, a measurement range of 0-5000 μW / cm is used. 2 The black light intensity value was measured at a distance of 150 mm from the standard sensitivity test block using a black light intensity meter.

[0011] Furthermore, in step S6, dual sensors are used for real-time monitoring. The white light illuminance sensor records the illuminance data of the workpiece surface every 1-2 minutes, and the black light intensity sensor records the black light intensity data of the detection area every 3-5 minutes. When the illuminance > Or black light intensity < If the white light intensity fluctuates significantly in a short period of time, the detection should be immediately paused and the parameters adjusted. In scenarios such as on-site inspection of large structures, the white light intensity is greatly affected by natural conditions and may fluctuate significantly in a short period of time. If the recording interval is too long (e.g., 5 minutes / time), the window period for parameter exceeding the limit will be missed, resulting in invalid detection data during this period. Therefore, high-frequency recording of 1-2 minutes can capture the dynamic changes in white light intensity in real time, avoiding problems that are not detected in time due to sudden increases in ambient light. The black light intensity is directly controlled by the black light lamp power, and the black light lamp is a fixed device in the detection scenario, with relatively stable power output and no natural environmental interference, so it will not fluctuate significantly in a short period of time. If the same high-frequency recording as white light is used (e.g., 1-2 minutes / time), it will lead to data redundancy, increase the workload of parameter verification for operators, and reduce detection efficiency. Therefore, a recording interval of 3-5 minutes can reduce redundant operations and balance parameter stability and detection process efficiency while ensuring the effectiveness of monitoring.

[0012] Furthermore, when the retest parameters are abnormal in step S7, they shall be handled according to the following rules: (1) If the parameter deviation is ≤10%, the appropriate black light intensity shall be recalculated through the correlation model, and the black light power shall be adjusted before the standard sensitivity test block is verified. If the target sensitivity defect can be clearly identified, the original test result shall be deemed valid; (2) If the parameter deviation is >10%, steps S2-S5 shall be executed again to re-inspect the workpiece throughout the entire process.

[0013] Furthermore, the process also includes a qualification verification step for testing personnel: all personnel involved in the testing must, under valid testing parameters, independently identify the defect corresponding to the target sensitivity on the standard sensitivity test block using a high-sensitivity CCD camera. Only those who can identify the defect accurately three times consecutively are allowed to participate in the workpiece testing. Those who fail to identify the defect accurately must undergo retraining and reassessment.

[0014] The beneficial effects of this invention are: (1) Filling the gap in illumination range technology and improving scene adaptability. For the illumination range of 20Lx to 500Lx that is not covered by the existing standard, there is no need to build a darkroom or carry multiple lighting equipment. Fluorescence penetration detection can be carried out directly. It is perfectly adapted to the scene where it is inconvenient to adjust the ambient light, such as field operations and on-site inspection of large storage tanks / ship decks. It solves the pain points of traditional technology equipment being difficult to carry, having high construction costs, and being limited in detection.

[0015] (2) Quantify the correlation of parameters and reduce the dependence on experience. A correlation model of white light illuminance-black light intensity-minimum identifiable defect size is constructed through a large number of controlled variable experiments. The formula replaces the traditional empirical parameter setting. The required black light intensity can be accurately calculated according to the target detection sensitivity, reducing the repeatability error of the detection results and greatly reducing the dependence on the operator's experience, thus meeting the standardized industrial detection needs.

[0016] (3) Optimize the whole process quality control to ensure the reliability of detection and introduce multi-stage quantitative quality control methods: In the pretreatment stage, the cleanliness is quantified by oil-soluble red fluorescent reagent to avoid impurities interfering with defect identification; in the detection, dual sensors are used to monitor parameters in real time, and adjustments are immediately paused when abnormal; during retesting, the deviation is graded and processed to ensure that the parameters of the whole process are controllable and reduce the false negative rate. Detailed Implementation

[0017] The specific embodiments of the present invention will be described in further detail below with reference to specific examples. These examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0018] To keep the embodiments concise, only the parts related to the present invention are schematically shown in the embodiments, and they do not represent the actual structure of the product. In addition, to make the embodiments concise and easy to understand, only one of the components with the same structure or function in the embodiments is schematically drawn, or only one of them is marked.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, specific implementation methods of the present invention will be described below. Obviously, those skilled in the art can obtain other similar structural products and other implementation methods based on this embodiment without any creative effort.

[0020] 1. Core Principles This method is applicable to scenarios with ambient light intensity between 20Lx and 500Lx. Its core lies in determining whether the yellow-green fluorescence generated by the fluorescent penetrant under a specific black light intensity can be effectively observed by quantifying the correlation between white light intensity, black light intensity and detection sensitivity. This allows for the accurate detection of product surface defects without the need to build an additional darkroom or add multiple lighting devices.

[0021] 2. Key Technology: Three-dimensional correlation model of illumination-black light-sensitivity White light illuminance was collected through numerous controlled variable experiments. Black light intensity Minimum identifiable defect size Specifically, a quantitative correlation model is established for the three core parameters of detection sensitivity, as detailed below: (1) Experimental data collection Variable control: White light illuminance range 20Lx-500Lx, with 20Lx intervals, for a total of 25 gradients; Black light intensity range 500μW / cm². 2 -3000μW / cm 2 100 μW / cm interval 2There are 26 gradients in total; the NACE standard sensitivity test block is used, containing artificial cracks of different widths from 0.05mm to 0.5mm.

[0022] Data recording: For each white light illuminance-black light intensity combination, the minimum identifiable crack width (D) was recorded using a high-sensitivity CCD camera with a resolution ≥12 million pixels and equipped with a 520-560nm yellow-green fluorescent filter observation block. A total of 25×26=650 sets of valid data were obtained.

[0023] (2) Construction of the association model Based on experimental data, a formula for calculating the minimum identifiable defect size was obtained through multiple linear regression analysis: ,in The smallest identifiable defect size, in mm. Black light intensity, measured in μW / cm² 2 , White light illuminance, in Lx, formula goodness of fit R 2 ≥0.92, error ≤5%.

[0024] (3) Generation of parameter quick lookup table Based on the above formula, a quick reference table of illumination-black light-sensitivity parameters is generated for rapid on-site determination of detection parameters.

[0025] 3. Detection Methods and Procedures Step 1: Workpiece pretreatment and cleaning Pre-treatment of the workpiece surface to be inspected: remove impurities such as oil, rust, and coatings, use ultrasonic cleaning at 300W power for 5 minutes, and then wipe with alcohol to ensure that there are no residues on the surface.

[0026] Step 2: White light illuminance measurement and initial parameter determination Using a high-precision white light illuminance meter with a range of 0-1000 Lx and an accuracy of ±2%, the illuminance at various points on the workpiece surface was measured, and the points with the highest illuminance were recorded. ; Determine the target sensitivity based on the detection requirements, and calculate the minimum required black light intensity using a parameter lookup table or formula. .

[0027] Step 3: Sensitivity test block verification test At the point of highest illuminance recorded in step 2, place a standard sensitivity test block with the same material as the workpiece. According to the proposed fluorescence penetrant detection standard, apply the fluorescence penetrant to the test block, let it stand for 5-10 minutes, remove the excess penetrant, apply the developer, and let it stand for 3-5 minutes. Using a black light intensity meter, with a measurement range of 0-5000 μW / cm 2 With an accuracy of ±3%, the black light intensity was measured at a distance of 150mm from the test block, and the black light power was gradually adjusted to... ≥ ; If the defect corresponding to the target sensitivity can be clearly identified by observing the test block with a CCD camera, such as a crack with D=0.1mm, then the current parameters ( , Effective; if unidentifiable, calculate the required additional black light intensity using the formula, increasing by 500 μW / cm². 2 Retest until the defect is visible.

[0028] Step 4: Verification of testing personnel qualifications All personnel involved in the inspection must independently identify the target sensitivity defects by observing the test block through a CCD camera under the illumination-black light parameters determined in step 3. If a person fails to accurately identify a defect three times in a row, they must be retrained and re-examined before they can participate in testing.

[0029] Step 5: Formal workpiece inspection and real-time parameter monitoring exist ≤ , ≥ Under these conditions, the workpiece is subjected to fluorescence penetrant testing according to the standard procedure; During the inspection, dual sensors are used for real-time monitoring: the white light illuminance sensor records the illuminance of the workpiece surface every 2 minutes, and the black light intensity sensor records the black light intensity of the inspection area every 5 minutes. If the parameters exceed the range, the inspection is immediately paused and adjusted.

[0030] Step 6: Retesting and Anomaly Handling After the test is completed, the highest illuminance and black light intensity of the workpiece surface are retested. If the parameters do not exceed the effective range of step 3, the test result is deemed valid. If during the retest > or < : If the parameter deviation is ≤10%, such as If the value exceeds the recorded value but is ≤550Lx, the required black light intensity is recalculated using the correlation formula. After adjustment, the test block is verified. If the defect is visible, the test result is valid. If the parameter deviation is > 10%, repeat steps 2-5 to perform a full-process re-inspection of the workpiece.

[0031] Finally, the method described in this application is merely a preferred embodiment and is not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A fluorescence penetrant detection method under white light conditions, characterized in that, Includes the following steps: S1. When the ambient light intensity is between 20Lx and 500Lx, a quantitative correlation model between white light intensity and black light intensity is established to determine whether the yellow-green fluorescence generated by the fluorescent penetrant under a specific black light intensity can be effectively observed, thereby discovering product surface defects. S2, Pre-treatment of the surface of the workpiece to be inspected to remove oil, rust and coating impurities; S3. Using a white light illuminance meter, measure the ambient white light illuminance values ​​at various points on the workpiece surface and record the illuminance value corresponding to the point with the highest illuminance. ; S4. Determine the target detection sensitivity D based on the detection requirements, and calculate the minimum required black light intensity using the aforementioned correlation model. ; S5. Place a standard sensitivity test block of the same material as the workpiece at the point of highest illuminance. After operating according to the preset fluorescence penetrant testing standard, adjust the black light power to ensure that the measured black light intensity is ≥ By observing the test block with a high-sensitivity CCD camera, if the defect corresponding to the target sensitivity can be clearly identified, the current situation can be determined. - For effective detection parameters; S6 performs formal inspection of the workpiece under effective detection parameter conditions, while simultaneously monitoring illuminance and black light intensity in real time. S7. After the test is completed, retest the parameters and process the test results according to the parameter deviation.

2. The fluorescence penetrant detection method under white light conditions according to claim 1, characterized in that, In step S1, the core formula of the association model is: ,in The smallest identifiable defect size, in mm. Black light intensity, measured in μW / cm² 2 , White light illuminance, measured in lux (Lx).

3. The fluorescence penetrant detection method under white light conditions according to claim 1, characterized in that, In step S2, the workpiece pretreatment adopts an ultrasonic cleaning combined with alcohol wiping process, wherein the ultrasonic cleaning power is 100-300W and the cleaning time is 5-30min, and the alcohol wiping uses industrial alcohol with a concentration of ≥95%.

4. The fluorescence penetrant detection method under white light conditions according to claim 1, characterized in that, In step S4, the standard sensitivity test block is the NACE standard test block, which contains artificial cracks of different widths from 0.05mm to 0.5mm; the high-sensitivity CCD camera has a resolution of ≥12 million pixels and is equipped with a 520-560nm yellow-green fluorescent filter.

5. The fluorescence penetrant detection method under white light conditions according to claim 1, characterized in that, Step S4 uses a measurement range of 0-5000 μW / cm 2 The black light intensity value was measured at a distance of 150 mm from the standard sensitivity test block using a black light intensity meter.

6. The fluorescence penetrant detection method under white light conditions according to claim 1, characterized in that, In step S6, dual sensors are used for real-time monitoring. The white light illuminance sensor records the illuminance data of the workpiece surface every 1-2 minutes, and the black light intensity sensor records the black light intensity data of the detection area every 3-5 minutes. When the illuminance > Or black light intensity < If this occurs, immediately pause the detection and adjust the parameters.

7. The fluorescence penetrant detection method under white light conditions according to claim 1, characterized in that, When the retest parameters are abnormal in step S7, the following rules shall be followed: (1) If the parameter deviation is ≤10%, the appropriate black light intensity shall be recalculated through the correlation model, and the black light power shall be adjusted before the standard sensitivity test block is verified. If the target sensitivity defect can be clearly identified, the original test result shall be deemed valid; (2) If the parameter deviation is >10%, steps S2-S5 shall be executed again to re-inspect the workpiece throughout the entire process.

8. The fluorescence penetrant detection method under white light conditions according to claim 1, characterized in that, It also includes a qualification verification step for testing personnel: all personnel involved in the testing must, under effective testing parameter conditions, independently identify the defect corresponding to the target sensitivity on the standard sensitivity test block using a high-sensitivity CCD camera. Only those who can identify the defect accurately three times in a row can participate in the workpiece testing. Those who fail to identify the defect accurately must undergo retraining and reassessment.

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