Penetration detection method for workpiece defects

Abstract

The invention discloses a penetration detection method for workpiece defects. The penetration detection method comprises the following steps: pre-cleaning and drying a workpiece; a penetrant is sprayed on the surface of the dried workpiece according to a preset path and a preset included angle, so that the surface of the workpiece is wetted by the penetrant, and the condition is kept for preset time; spraying, cleaning and drying the redundant penetrant on the surface of the workpiece; developing agent application is carried out on the dried workpiece, so that a defect image is displayed on the defect part of the workpiece; a defect image displayed on the workpiece is observed and recorded. According to the invention, the detection efficiency and sensitivity of workpiece defect detection can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of penetrant flaw detection, and in particular to a penetrant flaw detection method for workpiece defects. Background Art

[0002] During the production process, stainless steel workpieces may develop defects such as thermal cracks, stress corrosion cracks, pores, and slag inclusions, which can affect their performance. Penetrant testing is a nondestructive testing method for detecting open surface defects in non-porous materials. After a penetrant is applied to the workpiece surface, it penetrates into the open defects due to capillary action. Excess penetrant is then removed from the workpiece surface, dried, and a developer is applied. The developer, under capillary action, absorbs the penetrant from the defect onto the workpiece surface, revealing traces of the penetrant at the defect site and thereby detecting the morphological characteristics and distribution of the defect.

[0003] During penetrant testing, the application of the penetrant directly affects its uniform penetration and adsorption. After the penetrant wets the workpiece surface, excess penetrant in the inspected area is wiped away with a cloth or paper dipped in detergent. Over-cleaning during the wiping process can remove penetrant that has already penetrated the defect, resulting in missed detection of shallow and wide defects. Insufficient cleaning during the wiping process can make it difficult to distinguish the penetrant traces at the defect, also leading to missed detection and misjudgment of defects. Especially for underwater oil production forgings, a layer of high-hardness alloy steel is usually laser-clad for protection. The surface state of the workpiece prepared by the laser cladding process is relatively rough, affecting the uniform penetration and adsorption of the penetrant. Moreover, manual inspection is prone to misjudging or missing the penetration behavior of the penetrant at the laser cladding interface. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for penetrant detection of workpiece defects, which can improve the detection efficiency and sensitivity of workpiece defect detection.

[0005] In order to solve the above problems, the present invention discloses a method for penetrant detection of workpiece defects, comprising the following steps:

[0006] Pre-clean and dry the workpiece;

[0007] Spraying a penetrant on the dried surface of the workpiece along a preset path and at a preset angle, so that the penetrant wets the surface of the workpiece, and maintaining the penetrant for a preset time;

[0008] Spray cleaning and drying excess penetrant on the surface of the workpiece;

[0009] applying a developer to the dried workpiece so that a defective portion of the workpiece displays a defect image;

[0010] Observe and record the defect image displayed on the workpiece.

[0011] As an improvement of the above technical solution, the preset path is a reciprocating scanning path or a spiral scanning path; the preset angle is the angle between the penetrant injection direction and the workpiece surface, and the preset angle is 80° to 100°;

[0012] The aperture of the nozzle for spraying the penetrant is 0.5 mm to 2.0 mm, the distance between the nozzle and the surface of the workpiece is 15 cm to 30 cm, the spraying pressure is 0.2 MPa to 0.5 MPa, and the spraying speed is 0.1 m / s to 0.5 m / s.

[0013] As an improvement of the above technical solution, the preset time for the penetrant to wet the surface of the workpiece is 10 minutes to 30 minutes.

[0014] As an improvement to the above technical solution, after an interval of 5 to 10 minutes, the contact angle of the penetrant is detected, and if the contact angle is ≥10°, a second spraying of the penetrant is performed.

[0015] As an improvement of the above technical solution, the penetrant is a self-emulsifying penetrant;

[0016] The surface of the workpiece after spraying the penetrant is cleaned.

[0017] As an improvement of the above technical solution, the penetrant is a post-emulsification penetrant;

[0018] Cleaning excess penetrant from the workpiece surface comprises the following steps:

[0019] Pre-cleaning the surface of the workpiece after spraying the penetrant;

[0020] Apply emulsifier to the pre-cleaned workpiece surface and keep it for a preset time;

[0021] Clean the workpiece after applying the emulsifier.

[0022] As an improvement of the above technical solution, the method of applying the emulsifier includes immersing the workpiece in the emulsifier, or pouring the emulsifier onto the surface of the workpiece;

[0023] The emulsification time of the emulsifier is 1 min to 10 min, and the emulsification temperature of the emulsifier is 20° C. to 40° C.;

[0024] The HLB value of the emulsifier is 10-15, and the concentration of the emulsifier is 3%-10%.

[0025] As an improvement to the above technical solution, spray cleaning is performed on the workpiece surface after the emulsifier is applied using a preset path and a preset angle;

[0026] The preset path is a reciprocating scanning path or a spiral scanning path; the preset angle is the angle between the water jet direction and the workpiece surface, and the preset angle is 10° to 30°;

[0027] The distance between the water spraying nozzle and the surface of the workpiece is 20 cm to 40 cm, the spraying pressure is 0.1 MPa to 0.25 MPa, and the spraying speed is 0.1 m / s to 0.5 m / s.

[0028] As an improvement to the above technical solution, a developer is applied to the dried workpiece to form a developer film layer of a preset thickness;

[0029] The method of applying the developer includes spraying the developer uniformly on the surface of the workpiece, or immersing the workpiece in the developer.

[0030] The thickness of the developer film layer is 0.05 mm to 0.2 mm.

[0031] As an improvement of the above technical solution, the penetrant includes the following raw materials in parts by mass: 70 to 85 parts of deionized water, 2 to 7 parts of dye, 7 to 12 parts of surfactant, 20 to 40 parts of viscosity regulator, and 0.1 to 5 parts of functional additive; wherein the surfactant includes dodecylbenzene sulfonate and fatty alcohol polyoxyethylene ether, and the mass ratio of dodecylbenzene sulfonate and fatty alcohol polyoxyethylene ether is 1:(1.1 to 3); the viscosity regulator includes hydroxypropyl distarch phosphate and 1,2-propylene glycol, and the mass ratio of hydroxypropyl distarch phosphate and 1,2-propylene glycol is 1:(0.2 to 0.9).

[0032] The implementation of the present invention has the following beneficial effects:

[0033] In the penetrant testing method provided by the present invention, the penetrant spraying at a preset path and angle can achieve uniform penetration and wetting of the workpiece surface by the penetrant. The spray cleaning can improve the accuracy of penetrant removal and avoid defect omission caused by over-cleaning or insufficient cleaning. Finally, combined with the application of the developer, a clear and accurate defect image is obtained. Through the preset program of penetrant spraying, penetrant cleaning, and developer application, the present invention achieves efficient, high-sensitivity, and continuous detection of workpiece surface defects, reducing labor costs and repeated testing or waste losses caused by human error, meeting the needs of large-scale production, and is particularly suitable for defect detection of laser cladding workpieces. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0035] The present invention provides a method for penetrant detection of workpiece defects, comprising the following steps:

[0036] S1. Pre-clean and dry the workpiece.

[0037] The surface condition of a workpiece greatly affects the quality of penetrant testing. Rust, scale, paint, oil, and other contaminants on the workpiece surface can prevent the penetrant from penetrating into defects and even clog open defects on the workpiece surface, resulting in missed defects. Weld spatter, iron filings, and fiber on the workpiece surface can create false indications, leading to misjudgment of defects. Therefore, before spraying the penetrant, the workpiece surface should be thoroughly cleaned and pretreated to remove impurities such as oil, dust, and rust to improve surface cleanliness and roughness and enhance the adhesion of the penetrant to the surface. Cleaning with a detergent or detergent is usually recommended. If there are impurities on the surface of the test area that are difficult to clean, a stainless steel wire brush or grinding wheel can be used to remove them if necessary. After removal, cleaning with a detergent or other detergent can be performed.

[0038] S2. Automatically spray the penetrant on the surface of the dried workpiece along a preset path and at a preset angle, so that the penetrant wets the surface of the workpiece and maintains the wetness for a preset time.

[0039] In one embodiment, the preset path is a reciprocating scanning path or a spiral scanning path. The trajectory of the penetrant spray head is precisely planned based on the shape, size, and surface characteristics of the workpiece to ensure that the penetrant covers the entire inspection area and avoid omissions or local overspray. For planar workpieces, a parallel reciprocating scanning path can be used; for workpieces with complex shapes such as curved surfaces, a spiral scanning path can be used, with flexible path planning based on the contours. Automatically spraying the penetrant along the preset path can improve the uniformity and stability of the penetrant spray, achieving excellent penetrant wetting, especially for complex workpieces. In one embodiment, the preset angle is the angle between the penetrant spray direction and the workpiece surface. The preset angle is between 80° and 100°, with exemplary examples being 82°, 85°, 88°, 90°, 95°, or 98°, but not limited thereto. A suitable spraying angle allows the penetrant to better adhere to and spread on the workpiece surface. Generally, a spraying angle perpendicular to the surface to be inspected allows the droplets to fall vertically, reducing splashing and runoff on the surface and promoting uniform distribution. However, for some objects with special structures or inclined surfaces, the spraying angle needs to be adjusted according to the actual situation to ensure that the penetrant can be fully covered and evenly adhered.

[0040] It is understandable that the spraying effect can be further improved by matching appropriate penetrant spraying parameters. Among them, the aperture of the nozzle for spraying the penetrant is 0.5mm~2.0mm, the spraying speed is 0.1m / s~0.5m / s, the distance between the nozzle and the workpiece surface is 15cm~30cm, and the spraying pressure is 0.2MPa~0.5MPa. Generally speaking, a smaller nozzle aperture combined with appropriate pressure can produce smaller and more uniformly sized droplets, making the penetrant more evenly distributed on the surface being tested. When the surface opening of the defect is narrow and fine, and conventional penetration methods make it difficult for the penetrant to fully penetrate the defect, pressurization can be used to help the penetrant overcome resistance and better enter the interior of the defect, thereby improving the sensitivity and reliability of detection. In addition, for some workpieces with complex pore structures or tiny cracks inside, pressurized penetration also helps the penetrant penetrate deeper, so that potential defects can be more accurately detected. The specific spraying pressure can be determined based on factors such as the material, structure, defect type, and penetrant characteristics of the workpiece. For example, for thinner metal sheets, the spraying pressure can be appropriately reduced to avoid adverse effects such as deformation of the sheet; for thick-walled castings or ceramic materials, a relatively large spraying pressure can enable the penetrant to penetrate effectively.

[0041] In one embodiment, the preset time for the penetrant to wet the workpiece surface is 10 to 30 minutes, exemplified by, but not limited to, 14, 16, 18, 20, 24, or 28 minutes. A shorter wetting time may prevent the penetrant from fully penetrating the defect, affecting inspection effectiveness. A longer wetting time may result in excessive adsorption of the penetrant in non-defective areas, increasing the difficulty of subsequent cleaning and imaging, and also reducing inspection efficiency. The specific wetting time can be adjusted based on the defect content of the workpiece.

[0042] In a preferred embodiment, the contact angle of the penetrant is measured after an interval of 5 to 10 minutes. If the contact angle is ≥10°, a second spray of penetrant is performed. This timely measurement and second spray can compensate for insufficient wettability caused by factors such as surface contamination and penetrant volatilization, ensuring that the workpiece surface maintains good wettability throughout the entire inspection process.

[0043] Penetrants are mainly composed of solvents, dyes, surfactants, cosolvents, plasticizers, etc. Currently, a large number of banned or restricted substances are still present in commercially available penetrants, which not only endanger operator health but also pollute the environment through the discharge of waste liquids. Furthermore, for workpieces with rough surfaces, uneven coverage of the penetrant is likely to occur. After the penetrant has been wetted, more rigorous emulsification is necessary to completely clean the excess penetrant from the rough surface. However, excessive emulsification time can lead to the penetrant in the defects being mistakenly cleaned. Therefore, the present invention also provides a penetrant, particularly for workpieces with rough surfaces, to ensure the reliability of penetrant testing.

[0044] In one embodiment, the penetrant comprises the following raw materials in parts by weight: 70-85 parts deionized water, 2-7 parts dye, 7-12 parts surfactant, 20-40 parts viscosity modifier, and 0.1-5 parts functional additive. The surfactant comprises dodecylbenzene sulfonate and fatty alcohol polyoxyethylene ether, with the mass ratio of dodecylbenzene sulfonate to fatty alcohol polyoxyethylene ether being 1:1.1-3. The viscosity modifier comprises hydroxypropyl distarch phosphate and 1,2-propylene glycol, with the mass ratio of hydroxypropyl distarch phosphate to 1,2-propylene glycol being 1:0.2-0.9.

[0045] In addition, the dye can be one or more of amaranth, orpiment red, Congo red, carmine, and rose bengal. Functional additives can include, but are not limited to, rust inhibitors, cosolvents, and the like. Functional additives can be selected from conventional functional additives in the art.

[0046] The preparation method of the penetrant includes the following steps: adding dye to deionized water, stirring until completely dissolved, the stirring speed is 400r / min~600r / min, and the stirring time is 3h~4h, then adding surfactant, viscosity regulator and functional additive, and continuing stirring for 20min~40min to obtain the penetrant.

[0047] The penetrant provided by the present invention is a surfactant obtained by compounding dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether, which improves the spreading ability and capillary climbing height of the penetrant, and the penetrant has high wetting performance on the rough detection surface of the workpiece. The viscosity regulator obtained by compounding propyl distarch phosphate and 1,2-propylene glycol can adjust the viscosity of the penetrant to prevent the penetrant from being stratified when standing. Through the joint action of the surfactant and the viscosity regulator, the surface tension is adjusted, the penetrant is easy to penetrate and easy to clean, the time difference between penetration emulsification and imaging is short, the imaging is fast and the imaging is clear. In summary, by using the penetrant of the present application, the detection of defects can reach a sensitivity of more than level 2, the wettability on the rough surface is good and easy to clean, significantly enhances the detection accuracy, and reduces the error.

[0048] S3. Spray clean the excess penetrant on the workpiece surface and dry it.

[0049] If the penetrant is self-emulsifying, cleaning the excess penetrant involves spraying the workpiece surface after application. Self-emulsifying penetrants do not require a separate emulsification step; they can be directly sprayed with water. There is no separate emulsification time; the cleaning time determines the emulsification effect of the penetrant.

[0050] If the penetrant is a post-emulsified penetrant, cleaning of excess penetrant includes the following steps:

[0051] S31. Pre-clean the workpiece surface after spraying the penetrant.

[0052] After the penetrant is wetted, if an emulsifier is used directly for emulsification, a thick surface of the penetrant will require a large amount of emulsifier to complete the reaction, increasing costs. In addition, the emulsifier cannot evenly cover the thick penetrant film layer, and localized penetrant residue will create background noise, leading to an increased misjudgment rate. In one embodiment, the pre-cleaning can be performed using a spray pressure of 0.1MPa to 0.15MPa.

[0053] S32: applying an emulsifier to the pre-cleaned workpiece surface and maintaining the emulsifier for a preset time.

[0054] Specifically, the emulsifier application method includes immersing the workpiece in the emulsifier, or pouring the emulsifier onto the surface of the workpiece.

[0055] In one embodiment, the emulsification time of the emulsifier is 1 to 10 minutes. This emulsification time is a key factor in precisely controlling emulsification. If the emulsification time is too short, the penetrant will not be fully emulsified, hindering subsequent cleaning. If the emulsification time is too long, the penetrant will be over-emulsified, affecting detection sensitivity. The specific emulsification time depends on the type of penetrant, the surface condition of the workpiece, and the properties of the emulsifier. For materials with a rough surface, the emulsification time needs to be appropriately extended; for materials with a smooth surface, the emulsification time can be relatively short. In one embodiment, the emulsification temperature of the emulsifier is 20°C to 40°C. Temperature has a significant impact on the emulsification process. Appropriately increasing the temperature can reduce the viscosity of the penetrant and emulsifier, accelerate the mixing speed of the emulsifier and penetrant, and facilitate the emulsification process. However, excessively high temperatures may cause changes in the properties of the penetrant and emulsifier, affecting the emulsification effect. By controlling the emulsification temperature within an appropriate range, the activity of the emulsifier and the performance of the penetrant are relatively stable, achieving a better emulsification effect.

[0056] In one embodiment, the HLB value of the emulsifier is 10-15. An emulsifier with an appropriate HLB value is selected to ensure a good emulsification effect. In one embodiment, the concentration of the emulsifier is 3% to 10%. The concentration of the emulsifier has a significant impact on the emulsification effect. If the concentration is too low, the penetrant cannot be fully emulsified, making it difficult to remove excess penetrant, affecting the test results. If the concentration is too high, over-emulsification may occur, causing the active ingredients in the penetrant to be encapsulated by the emulsifier, reducing the penetrant's ability to penetrate the defect. It is understood that the emulsifier can be selected from commercially available emulsifiers commonly used in the field.

[0057] S33, cleaning the workpiece after the emulsifier is applied.

[0058] In one embodiment, spray cleaning is performed on the workpiece surface after the emulsifier is applied, using a preset path and a preset angle.

[0059] Specifically, the preset path is a reciprocating scanning path or a spiral scanning path; the preset angle is the angle between the water spray direction and the workpiece surface, and the preset angle is 10° to 30°; the distance between the water spray nozzle and the workpiece surface is 20cm to 40cm, the spray pressure is 0.1MPa to 0.25MPa, and the spray speed is 0.1m / s to 0.5m / s. Compared with using a clean, non-linting cloth to lightly dip the emulsifier and then wipe, the spray cleaning method of the present invention can effectively control the removal effect of the penetrant and avoid errors caused by manual operation.

[0060] S4. Applying a developer to the dried workpiece to display a defect image on the defective portion of the workpiece.

[0061] Specifically, a developer is applied to the dried workpiece to form a developer film layer of a predetermined thickness. In one embodiment, the thickness of the developer film layer is 0.05 mm to 0.2 mm. A developer film layer that is too thick will result in a blurred background, affecting defect identification; a developer film layer that is too thin may not fully absorb the penetrant, resulting in unclear defect display. Generally speaking, the thickness of the developer film layer formed by a dry powder developer is 0.05 mm to 0.1 mm, and the thickness of the developer film layer formed by a wet developer is 0.1 mm to 0.2 mm.

[0062] The developer application method includes spraying the developer evenly onto the workpiece surface or immersing the workpiece in the developer. The spraying method involves using a spray gun to evenly spray the developer onto the workpiece surface. The spray volume and coverage are controlled by adjusting the nozzle size, pressure, and speed of the developer spray gun. Generally, the nozzle aperture for spraying the developer is 1 mm to 2 mm, the spray pressure is 0.2 MPa to 0.3 MPa, and the spray speed is 3 cm / s to 5 cm / s. During spraying, maintain a distance of ≥ 300 mm from the workpiece surface and move at a uniform speed to ensure uniform coverage of the developer. Preferably, the distance from the workpiece surface during spraying is 400 mm to 800 mm. Angle spraying can improve the developer's appearance. In a preferred embodiment, the developer spray direction maintains a 30° to 40° angle with the workpiece surface. The dip coating method involves completely immersing the workpiece in the developer, allowing the developer to fully adhere to the workpiece surface. The immersion time depends on the workpiece material, surface condition, and developer type, and is generally 1 to 3 minutes. After immersion, slowly remove the workpiece, allowing excess developer to drip back into the container. It should be understood that the developer can be any commercially available developer commonly used in the art.

[0063] In addition, after applying the developer, the workpiece needs to be dried to form a clear developed image. The drying method can be natural drying, hot air drying or infrared drying, etc. During natural drying, the workpiece is placed in a well-ventilated and dust-free environment. The drying time depends on the ambient temperature and humidity, and generally takes 10 minutes to 30 minutes. During hot air drying, the workpiece is placed in a drying oven with a drying temperature of ≤70°C. Preferably, the drying temperature is 40°C to 60°C, and the drying time is 5 minutes to 15 minutes. During infrared drying, the infrared lamp is placed 15cm to 20cm away from the surface of the workpiece, and the irradiation time is 3 minutes to 10 minutes. Infrared drying has the advantages of fast drying speed and high efficiency.

[0064] S5. Observe and record the defect image displayed on the workpiece.

[0065] It is understood that defect images are generally identified by the human eye after image acquisition, or they can be identified with the assistance of a computer, using image processing and pattern recognition technology to analyze and process the acquired images. Algorithms are used to extract feature information from the image and compare it with a preset defect feature model to achieve automatic defect identification.

[0066] Among them, the width and length of the defect can be distinguished by image recognition to determine the specific size data, and the depth detection of the defect can be assisted by X-ray or ultrasonic flaw detection devices.

[0067] It is understandable that the material of the workpiece detected by the penetration detection method of the present invention can be metal, or other non-porous materials that are inert to the penetrating material (such as castings, forgings, welded parts, ceramics, etc.), but it is not limited to this. In particular, the penetration detection method provided by the present invention can be used for penetration detection of laser-clad wear-resistant belts, which has high reliability and good removability of the penetrant. During the drilling process, the drill pipe is in direct contact with the well wall or casing, and repeated friction and collision cause rapid wear, which greatly shortens the service life of the drill pipe. For this reason, traditional steel drill pipe joints are usually laser-clad with a layer of high-hardness alloy steel wear-resistant belt to protect the drill pipe joint, reduce drilling costs, and improve drilling efficiency.

[0068] The surface state of the workpiece prepared by the laser cladding process is relatively rough, and there may be tiny pores, unevenness or tiny welding defects, which affect the uniform penetration and adsorption of the penetrant, resulting in inaccurate detection results. In addition, the bonding interface between the cladding layer and the substrate is also relatively complex, and there may be areas with loose bonding. The penetration behavior of the penetrant at the interface is difficult to accurately judge, and manual inspection is prone to misjudgment or omission. Moreover, the wear-resistant belt is usually composed of a variety of alloy elements, and its chemical composition and physical properties are different from those of the substrate material. Different materials have different adsorption, penetration and residual characteristics of the penetrant. The thermal expansion coefficients of the materials are different. During the detection process, temperature changes may cause tiny gaps or stresses between the cladding layer and the substrate, affecting the repeatability and reliability of the penetration test.

[0069] Defects found in laser-clad hardbanding include pores, cracks, and lack of fusion. Each defect type has distinct shapes, sizes, and distributions, resulting in varying penetration and visualization effects on penetrants, complicating detection. Some of these tiny defects, such as microcracks, can be micrometers wide. Conventional penetrant testing methods hinder their full penetration and hinder their clear visualization during imaging, making them easily missed.

[0070] In addition, in the existing penetration testing methods, it is difficult to completely remove the penetrant and developer residues on the rough surface of the laser-clad wear-resistant belt. Especially in complex surface structures and tiny pores, the residual substances may have an adverse effect on the performance of the wear-resistant belt, such as causing corrosion and reducing wear resistance. In the process of removing the residual substances, if the method used is inappropriate, it may cause damage to the surface of the wear-resistant belt, affecting its performance and life.

[0071] The penetration testing method of the present invention uses fully automated testing to quickly and continuously detect defects in laser-clad wear-resistant belts according to preset procedures, without the need for frequent manual operations. This greatly shortens the testing time of a single workpiece, reduces labor costs and repeated testing or waste losses due to human errors, enables batch testing, significantly improves overall testing efficiency, and meets the needs of large-scale production.

[0072] First, the penetrant testing method of the present invention enhances detection accuracy and consistency. Through precise mechanical movement and parameter control, the automated testing equipment ensures that every step of the penetrant testing process, such as penetrant spraying, emulsification time control, cleaning, and imaging, is accurately executed according to the set standards. This reduces detection errors caused by human factors, improves the accuracy and consistency of test results, and makes the test data more reliable.

[0073] Secondly, the penetrant testing method of the present invention enables real-time monitoring and data management. The automated testing system, equipped with sensors and image acquisition equipment, monitors the testing process in real time, promptly identifying defects on the wear-resistant belt surface and enabling precise location and quantitative analysis of these defects. Furthermore, the system automatically records test data and images, facilitating product quality traceability and analysis, and providing a basis for optimizing the laser cladding process.

[0074] Thirdly, the penetrant testing method of the present invention can reduce manual labor intensity and safety costs. Fully automated testing reduces manual involvement and the labor intensity of operators, a particularly significant advantage when testing large or complex laser-clad wear-resistant belts. The penetrant has low toxicity and volatility, posing minimal health risks to operators during the testing process while also reducing environmental pollution. This is of great significance for testing laser-clad wear-resistant belts in various working environments, meeting the requirements of modern industry for safe production and environmental protection.

[0075] The present invention will be further described below with specific embodiments:

[0076] Example 1

[0077] This embodiment provides a method for penetrant detection of workpiece defects, comprising the following steps:

[0078] S1. Pre-clean and dry the workpiece.

[0079] S2. Spraying the penetrant on the dried workpiece surface along a preset path and at a preset angle so that the penetrant wets the workpiece surface and maintains the wetted state for a preset time.

[0080] The penetrant is automatically sprayed in a spiral scanning path. The preset angle is the angle between the penetrant spraying direction and the workpiece surface. The preset angle is 90°. The aperture of the nozzle for spraying the penetrant is 1mm, the spraying speed is 0.2m / s, and the distance between the nozzle and the workpiece surface is 20cm.

[0081] The preset time for the penetrant to wet the workpiece surface is 20 minutes.

[0082] S3. Spray clean the excess penetrant on the workpiece surface and dry it.

[0083] Cleaning of excess penetrant involves the following steps:

[0084] S31. Pre-clean the workpiece surface after spraying the penetrant.

[0085] Spraying was performed at a spraying pressure of 0.1 MPa.

[0086] S32: applying an emulsifier to the pre-cleaned workpiece surface and maintaining the emulsifier for a preset time.

[0087] The workpiece is immersed in the emulsifier, the emulsification time of the emulsifier is 5 minutes, and the emulsification temperature of the emulsifier is 30°C.

[0088] S33, cleaning the workpiece after the emulsifier is applied.

[0089] The angle between the water spray direction and the workpiece surface is 30°, the distance between the water spraying nozzle and the workpiece surface is 40 cm, the spraying pressure is 0.15 MPa, and the spraying speed is 0.3 m / s.

[0090] S4. Applying a developer to the dried workpiece to display a defect image on the defective portion of the workpiece.

[0091] The wet developer was automatically sprayed on the surface of the workpiece. The distance between the nozzle and the workpiece surface was 500 mm. The angle between the developer spray direction and the workpiece surface was 35°. The thickness of the developer film layer was 0.15 mm. The developer was then dried in hot air at 50°C for 10 minutes.

[0092] S5. Observe and record the defect image displayed on the workpiece.

[0093] The penetrant, emulsifier and developer all adopt DPT-5 flaw detection agent produced by Shanghai Xinmeida Flaw Detection Equipment Co., Ltd.

[0094] Example 2

[0095] This embodiment provides a method for penetrant detection of workpiece defects. The difference between this method and embodiment 1 is that after the penetrant is sprayed for 8 minutes, the contact angle of the penetrant is detected. If the contact angle is ≥10°, the penetrant is sprayed a second time.

[0096] The rest are the same as in Example 1.

[0097] Example 3

[0098] This embodiment provides a penetrant detection method for workpiece defects. This method differs from Example 2 in that the penetrant comprises the following raw materials in parts by weight: 80 parts deionized water, 3 parts dye, 8 parts surfactant, 25 parts viscosity modifier, and 3 parts functional additive. The surfactant comprises dodecylbenzene sulfonate and fatty alcohol polyoxyethylene ether, with the mass ratio of dodecylbenzene sulfonate to fatty alcohol polyoxyethylene ether being 1:1. The viscosity modifier comprises hydroxypropyl distarch phosphate and 1,2-propylene glycol, with the mass ratio of hydroxypropyl distarch phosphate to 1,2-propylene glycol being 1:1.

[0099] The rest are the same as in Example 2.

[0100] Example 4

[0101] This embodiment provides a method for penetrant testing of workpiece defects, which differs from embodiment 3 in that the mass ratio of dodecylbenzenesulfonate to fatty alcohol polyoxyethylene ether is 1:1.5, and the mass ratio of hydroxypropyl distarch phosphate to 1,2-propylene glycol is 1:0.5.

[0102] The rest are the same as in Example 2.

[0103] Comparative Example 1

[0104] This embodiment provides a method for penetrant detection of workpiece defects, comprising the following steps:

[0105] S1. Pre-clean and dry the workpiece.

[0106] S2. Manually spray the penetrant on the dried workpiece surface to allow the penetrant to wet the workpiece surface and maintain it for 20 minutes.

[0107] S3. Clean the excess penetrant on the surface of the workpiece.

[0108] First, wipe it roughly with a cloth to remove most of the excess penetrant on the surface of the workpiece, then apply the emulsifier evenly to the penetrant on the surface of the workpiece by manual spraying, and finally wipe the surface of the workpiece clean with a clean cloth.

[0109] S4. Applying a developer to the dried workpiece to display a defect image on the defective portion of the workpiece.

[0110] The wet developer was manually sprayed on the surface of the workpiece to form a developer film with a thickness of 0.15 mm, and then dried in hot air at 50° C. for 10 minutes.

[0111] S5. Observe and record the defect image displayed on the workpiece.

[0112] The penetrant, emulsifier and developer all adopt DPT-5 flaw detection agent produced by Shanghai Xinmeida Flaw Detection Equipment Co., Ltd.

[0113] According to GB / T 18851.1-2024 "Nondestructive Testing Penetrant Testing", the workpieces obtained by the penetrant testing method of Examples 1 to 4 and Comparative Example 1 were tested, and the results are shown in the following table:

[0114]

[0115] The above is a preferred embodiment of the invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for penetrant detection of workpiece defects, characterized in that: The following steps are involved: Pre-clean and dry the workpiece; Spraying a penetrant on the dried surface of the workpiece along a preset path and at a preset angle, so that the penetrant wets the surface of the workpiece, and maintaining the penetrant for a preset time; Spray cleaning and drying excess penetrant on the surface of the workpiece; applying a developer to the dried workpiece so that a defective portion of the workpiece displays a defect image; Observe and record the defect image displayed on the workpiece.

2. The method for penetrant detection of workpiece defects according to claim 1, wherein: The preset path is a reciprocating scanning path or a spiral scanning path; the preset angle is the angle between the penetrant injection direction and the workpiece surface, and the preset angle is 80° to 100°; The aperture of the nozzle for spraying the penetrant is 0.5 mm to 2.0 mm, the distance between the nozzle and the surface of the workpiece is 15 cm to 30 cm, the spraying pressure is 0.2 MPa to 0.5 MPa, and the spraying speed is 0.1 m / s to 0.5 m / s.

3. The method for penetrant detection of workpiece defects according to claim 1, wherein: The preset time for the penetrant to wet the surface of the workpiece is 10 minutes to 30 minutes.

4. The method for penetrant detection of workpiece defects according to claim 1, wherein: After an interval of 5 to 10 minutes, the contact angle of the penetrant is measured. If the contact angle is ≥10°, a second spraying of the penetrant is performed.

5. The method for penetrant detection of workpiece defects according to claim 1, wherein: The penetrant is a self-emulsifying penetrant; The surface of the workpiece after spraying the penetrant is cleaned.

6. The method for penetrant detection of workpiece defects according to claim 1, wherein: The penetrant is a post-emulsifying penetrant; Cleaning excess penetrant from the workpiece surface comprises the following steps: Pre-cleaning the surface of the workpiece after spraying the penetrant; Apply emulsifier to the pre-cleaned workpiece surface and keep it for a preset time; Clean the workpiece after applying the emulsifier.

7. The method for penetrant detection of workpiece defects according to claim 6, wherein: The emulsifier application method includes immersing the workpiece in the emulsifier, or pouring the emulsifier onto the surface of the workpiece; The emulsification time of the emulsifier is 1 min to 10 min, and the emulsification temperature of the emulsifier is 20° C. to 40° C.; The HLB value of the emulsifier is 10-15, and the concentration of the emulsifier is 3%-10%.

8. The method for penetrant detection of workpiece defects according to claim 6, wherein: Spray cleaning is performed on the workpiece surface after the emulsifier is applied using a preset path and a preset angle; The preset path is a reciprocating scanning path or a spiral scanning path; the preset angle is the angle between the water jet direction and the workpiece surface, and the preset angle is 10° to 30°; The distance between the water spraying nozzle and the surface of the workpiece is 20 cm to 40 cm, the spraying pressure is 0.1 MPa to 0.25 MPa, and the spraying speed is 0.1 m / s to 0.5 m / s.

9. The method for penetrant detection of workpiece defects according to claim 1, wherein: Applying a developer to the dried workpiece to form a developer film layer of a preset thickness; The method of applying the developer includes spraying the developer uniformly on the surface of the workpiece, or immersing the workpiece in the developer. The thickness of the developer film layer is 0.05 mm to 0.2 mm.

10. The method for penetrant detection of workpiece defects according to claim 1, wherein: The penetrant includes the following raw materials in parts by mass: 70 to 85 parts of deionized water, 2 to 7 parts of dye, 7 to 12 parts of surfactant, 20 to 40 parts of viscosity regulator, and 0.1 to 5 parts of functional additive; wherein the surfactant includes dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether, and the mass ratio of dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether is 1:(1.1 to 3); the viscosity regulator includes hydroxypropyl distarch phosphate and 1,2-propylene glycol, and the mass ratio of hydroxypropyl distarch phosphate and 1,2-propylene glycol is 1:(0.2 to 0.9).

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