A system for measuring the depth of localized corrosion defects

Abstract

This utility model discloses a system for measuring the depth of localized corrosion defects, comprising: a grating module mounted on a fixed housing, which includes a measuring grating with adjustable grating scale; a structured light scanner located above the grating module, used to generate a structured light source passing through the grating surface formed by the measuring grating so that the structured light source illuminates the measuring area containing pitting defects, and scans the measuring area along at least two planar directions; and an information processing module used to obtain point cloud data in at least two planar directions to determine the depth of the target pitting defect.

Description

Technical Field

[0001] This utility model relates to the field of corrosion defect detection technology, and in particular to a system for measuring the depth of local corrosion defects. Background Technology

[0002] Stainless steel possesses excellent corrosion resistance, making it a popular material for many critical equipment and pipelines in the chlor-alkali chemical industry. However, in chlorine-containing environments, stainless steel surfaces are prone to pitting corrosion, especially at welds and seals. Because most pits are very small, measuring their size is difficult, and they are often obscured by corrosion products, remaining undetected until the equipment has perforated. Since various products of the chlor-alkali industry are highly toxic, explosive, and corrosive, severe pitting corrosion leading to leaks can cause serious injuries and significant economic losses. Therefore, timely detection of even minute pitting on chlor-alkali equipment and prevention of its further development can eliminate the risk of perforation and leakage, possessing significant economic value and practical importance.

[0003] Currently, the detection of pitting corrosion mainly relies on manual visual inspection. Traditional detection methods are costly, highly dependent on manual labor, and inefficient, making them unsuitable for large-scale application in chlor-alkali chemical environments. They also pose certain safety risks and operational difficulties. Because pitting defects typically manifest as localized small holes or pits, their uneven distribution and small size (<1mm) often lead to them being overlooked or missed by traditional detection methods.

[0004] Meanwhile, existing detection methods include magnetic flux leakage, pulsed eddy current, and ultrasonic guided wave nondestructive testing, but these methods are all focused on qualitative analysis, and there is still a lack of feasible means for quantitative analysis of pitting defects. Moreover, current research on surface defect detection based on structured light is still at the level of a simple task of detecting defects on the surface of textureless objects using traditional two-dimensional machine vision algorithms, and accurate measurement of the depth of pitting defects cannot be achieved.

[0005] In summary, the current technology needs to provide an efficient, accurate, and reliable quantitative analysis scheme for pitting corrosion defects, which is an urgent problem to be solved. Utility Model Content

[0006] The purpose of this invention is to propose an efficient, accurate, and reliable quantitative analysis scheme for pitting corrosion defect detection.

[0007] To address the aforementioned technical problems, this utility model provides a system for measuring the depth of localized corrosion defects, comprising: a grating module mounted on a fixed housing, including a measuring grating with adjustable grating scale; a structured light scanner located above the grating module, used to generate a structured light source passing through the grating surface formed by the measuring grating so that the structured light source illuminates the measurement area containing pitting defects, and scans the measurement area along at least two planar directions; and an information processing module used to obtain point cloud data in at least two planar directions to determine the depth of the target pitting defect.

[0008] Preferably, the fixed housing is a cylindrical structure, and the measuring grating is a circular grating, which is installed on the radial section of the internal space of the cylindrical fixed housing.

[0009] Preferably, the scale of the measuring grating is adjusted using a grating adjustment member disposed on the outer wall of the cylindrical fixed housing.

[0010] Preferably, the grating module includes a circular grating with at least two scales.

[0011] Preferably, the grating module includes three circular gratings with different scale levels, the scales of the three circular gratings being 1 / 10, 1 / 50, and 1 / 100 respectively.

[0012] Preferably, the structured light scanner is located directly above the geometric center of the grating surface.

[0013] Preferably, the bottom end of the cylindrical fixed housing is provided with an opening, and the top end of the cylindrical fixed housing is constructed with a through hole, so that the structured light scanner is confined directly above the grating module by passing through the through hole.

[0014] Preferably, the edge of the through hole also has a snap-fit ​​assembly for fixing the structured light scanner.

[0015] Preferably, the system further includes a two-dimensional image acquisition module, which is used to acquire an image containing complete target pitting defect planar information, wherein the two-dimensional image acquisition module has a white light source to provide a light source for acquiring the two-dimensional image.

[0016] Preferably, the white light source is an annular white light source, wherein the annular white light source is installed on the annular area between the through hole in the top of the cylindrical fixed housing and the side wall of the fixed housing.

[0017] Preferably, the projection surface of the structural light source is parallel to the plane of the measurement area and the grating surface.

[0018] Preferably, the at least two planar directions are perpendicular to each other.

[0019] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0020] This invention proposes a system for measuring the depth of localized corrosion defects. The system employs a combination of two-dimensional imaging and unidirectional parallel-line structured light scanning, significantly reducing the computational load of three-dimensional imaging and dimensional measurement processes while improving the speed of pitting depth detection. Compared to traditional manual inspection or other machine vision inspection methods, this invention enhances the detection capability of three-dimensional defects on object surfaces, overcomes the influence of ambient light on defect detection, and eliminates the need for complete scanning and imaging of the entire test plane, saving multiple steps such as post-imaging point cloud editing, smoothing, stitching, and optimization, thus enabling rapid measurement of pitting. Furthermore, this invention can be widely applied to non-contact, non-destructive testing and measurement of corrosion defects in equipment in the petroleum and chemical industries, with no requirements on the material of the inspected equipment or the environment in which it is located, effectively improving the accuracy of defect detection and the efficiency of automated inspection.

[0021] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of this invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used in conjunction with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic diagram of the overall structure of a system for measuring the depth of localized corrosion defects according to an embodiment of this application.

[0024] Figure 2 This is an example of the imaging effect of a two-dimensional image in a system for measuring the depth of localized corrosion defects according to an embodiment of this application.

[0025] Figure 3 This is a schematic diagram of the structure of the structured light projection part in the system for measuring the depth of localized corrosion defects according to an embodiment of this application.

[0026] Figure 4 This is a schematic diagram of a system for measuring the depth of localized corrosion defects according to an embodiment of this application, in which the measurement area is scanned along at least two planar directions. Detailed Implementation

[0027] The following detailed description of the embodiments of this utility model, in conjunction with the accompanying drawings, will provide a thorough understanding of how this utility model uses technical means to solve technical problems and achieve technical effects, enabling its implementation. It should be noted that, provided there is no conflict, the various embodiments and features within them can be combined with each other, and all resulting technical solutions are within the protection scope of this utility model.

[0028] Furthermore, the steps illustrated in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although a logical order is shown in the flowcharts, in some cases the steps shown or described may be performed in a different order than that shown here.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0030] To address the problems mentioned above, this invention provides a system for measuring the depth of localized corrosion defects. This system utilizes the difference in reflected light from an illumination source between a stainless steel pit and its surrounding surface to form a rapid pitting identification scheme based on white light illumination, and measures the pitting depth using single-line structured light scanning.

[0031] Example 1

[0032] Figure 1 This is a schematic diagram of the overall structure of a system for measuring the depth of localized corrosion defects according to an embodiment of this application. The following references... Figure 1 The overall structure and function of the system for measuring the depth of local corrosion defects (also known as the "defect depth measurement system") described in the embodiments of this utility model are explained.

[0033] like Figure 1 As shown in the embodiment of this utility model, the defect depth measurement system includes at least: a two-dimensional image acquisition module, a fixed housing, a grating module, a structured light scanner, and an information processing module.

[0034] In this embodiment of the invention, the area to be measured is a device wall containing a pitting defect, and the image acquisition field of view is a preset area of ​​a preset size. The wall can be either an inner wall or an outer wall.

[0035] The two-dimensional image acquisition module is used to acquire images containing complete planar information of the target pitting defect, denoted as a two-dimensional image of the pitting defect. In this embodiment of the invention, the image acquisition field of view in the two-dimensional image acquisition module needs to include the complete morphology of all tested target pitting defects within a preset area, see [link to relevant documentation]. Figure 2 (b) Figure 2 (c)

[0036] The mounting housing is a cylindrical structure, positioned directly above the area being measured (i.e., the area being scanned). A grating module is mounted on the cylindrical mounting housing. The grating module also includes a measuring grating with adjustable scale, capable of forming a corresponding grating surface with multiple grating slits distributed on it. In one embodiment, the scale level of the measuring grating can be determined based on the size of the pitting opening region indicated in a two-dimensional image of the pitting defect.

[0037] Furthermore, the structured light scanner is located above the grating module. The structured light scanner generates a structured light source that passes through the grating surface formed by the measurement grating, allowing the structured light source to illuminate the measurement area containing pitting defects through the grating gaps. Then, the structured light scanner scans the measurement area along at least two planar directions to obtain point cloud data containing the depth feature information of the target pitting defects for each planar direction. See the schematic diagram of the scanning scene. Figure 4 (a) Figure 4 (b). The structured light source generated is a unidirectional parallel line structured light.

[0038] In this embodiment of the invention, the information processing module is used to acquire point cloud data from at least two planar directions obtained from the structured light scanner, so as to use the point cloud data to determine the depth measurement value of the target pitting defect.

[0039] Furthermore, the information processing module is also used to determine the installation position of the structured light scanner based on the pitting area indicated in the acquired two-dimensional image of the pitting defect, so that the structured light scanner is positioned directly above any pitting area within the preset area range. Therefore, in this embodiment of the invention, the range of the scanned area is smaller than the preset area range because it only contains one pitting area.

[0040] Traditional structured light 3D inspection methods lack recognition capabilities, requiring a comprehensive scan of the entire surface to be measured. After scanning, the point cloud needs editing and smoothing, followed by manual location of corrosion defects based on the processed image, and then depth measurement of the target corrosion defect. However, this invention eliminates the need for manual location of corrosion defects from scanned images. Instead, it actively identifies the location of corrosion defects by taking a 2D image, then only scans and measures the area containing the defect, eliminating the need for a complete scan and imaging of the entire surface. This simplifies the multiple steps of post-imaging point cloud editing, smoothing, stitching, and optimization, enabling rapid measurement of pitting corrosion.

[0041] Example 2

[0042] Based on the defect depth measurement system provided in Embodiment 1, the specific structure, function, and application scenarios of the defect depth measurement system described in this embodiment of the present invention will be further explained below.

[0043] The two-dimensional image acquisition module includes a white light source and a camera. The white light source provides the light source for capturing two-dimensional images of pitting defects.

[0044] In one embodiment, the white light source is a ring-shaped white light source. The light intensity of the ring-shaped white light source is adjustable.

[0045] During the process of capturing two-dimensional images of pitting defects using a two-dimensional image acquisition module, the power supply of the white light source is turned on, and the illumination source is projected onto the tested area of ​​the corroded surface. This illumination source is a white light ring light source with N ≥ 50 pcs; the inner diameter of the light source ring is ≤ 6 cm; the white light output power is ≥ 4.5 W; the illumination working distance is 180–400 mm; and the color temperature index of the white light source is adjustable from 6500 K to 7000 K.

[0046] After the surface of the area to be tested is illuminated, a camera is used to capture a two-dimensional image of the pitting defect, so that image processing technology can be used to identify the opening size of the target pitting area in the two-dimensional image of the pitting defect. Figure 2 (a) Figure 2 (b) The pitting imaging results of stainless steel before and after white light excitation are shown respectively. For those skilled in the art, identifying the size of a specific area from an image is a relatively mature technology, and this utility model will not elaborate on this.

[0047] Furthermore, the grating module includes: a measurement grating with adjustable scale. In this embodiment of the invention, as... Figure 3 As shown, the measuring grating is a circular grating. This circular grating is mounted on the radial section of the internal space of the cylindrical fixed housing.

[0048] In this embodiment of the invention, the scale level of the measuring grating (i.e., the distribution density of the grating slits) can be adjusted using a grating adjustment component (e.g., a button or knob) located on the outer wall of the cylindrical fixed housing (e.g., stepless adjustment or adjustment with interval steps). See [link to relevant documentation]. Figure 2 .

[0049] In one embodiment, the size of the pitting opening region is negatively correlated with the grating scale level.

[0050] Therefore, this invention proposes a structured light projection structure with adjustable grating scale. The grating scale level selected for depth measurement varies depending on the size of the pitting. For relatively large pits, a denser grating is used for projection; for relatively small pits, a sparser grating is used.

[0051] To achieve better scanning results, the structured light scanner described in this embodiment is located directly above the geometric center of the grating surface. (See [link]). Figure 4 (a) Figure 4 (b)

[0052] Furthermore, the bottom of the cylindrical fixed housing is provided with an opening, and the top of the cylindrical fixed housing is constructed with a through hole, so that the structured light scanner is confined directly above the grating module by passing through the through hole.

[0053] In addition, the defect depth measurement system described in this embodiment of the invention further includes a clip assembly (not shown) for fixing the structured light scanner. The clip assembly is disposed at the edge of the aforementioned through hole. This clip assembly is used to fix the structured light scanner directly above the grating module.

[0054] Furthermore, the structured light scanner includes a scanner and a scanner housing. The scanner is located within the internal space of the scanner housing. The scanner housing has a cylindrical structure, and its outer diameter matches the diameter of the aforementioned through-hole, allowing for a seamless, sealed fixation of the structured light scanner to the cylindrical housing via a snap-fit ​​assembly. The bottom of the scanner housing has an opening, allowing the structured light generated by the scanner to pass through the bottom of the scanner housing and enter the internal space of the cylindrical housing, thereby passing through the grating surface inside the cylindrical housing and reaching the measured area corresponding to a pitted area.

[0055] Furthermore, in order to optimize the structure of the entire defect depth measurement system, such as Figure 3 As shown, the aforementioned annular white light source is installed on the annular area between the through hole at the top of the cylindrical fixed housing and the side wall of the housing.

[0056] After adjusting the grating scale, the structured light source is projected and the measurement area is scanned. In this embodiment of the invention, the wavelengths of the structured light source are 650nm, 520nm, and 450nm, the power of the structured light source is ≥100W, the operating voltage is ≤5.5V, and the operating current is <500mA.

[0057] Furthermore, in this embodiment of the invention, the projection surface of the structural light source is parallel to the plane of the measurement area and the grating surface.

[0058] Since the projection surface of the structured light source is parallel to the plane of the stainless steel to be measured, when the structured light scans to the pitted area being measured, the linear structured light is deformed, and this deformation varies with the depth of pitting.

[0059] The structured light scanner then scans the measurement area along at least two planar directions. These at least two planar directions are perpendicular to each other. That is, among the at least two planar directions scanned, there are two mutually perpendicular planar directions.

[0060] like Figure 4 As shown in (a), the structured light source generated by the structured light scanner scans along the first plane direction (x direction) until the scanning range includes the complete target pitting defect; then, as... Figure 4 As shown in (b), the structured light generated by the structured light scanner continues to scan along the second plane direction (y direction) until the scanning range contains the complete current target pitting defect; thus, after scanning in both the X and Y directions, point cloud data containing the current target pitting defect region is obtained, so as to obtain the depth measurement result of the target pitting based on the point cloud data in the two scanning directions.

[0061] In one embodiment, the maximum Z-coordinate value in the point cloud data from the two scanning directions can be used as the measurement result.

[0062] Therefore, traditional structured light detection methods use cross-line lasers to scan all surfaces in the area under test and then image them. This process requires multiple steps, such as editing, smoothing, stitching, and optimization, to achieve three-dimensional reconstruction of the entire plane, which is time-consuming. However, this invention uses unidirectional parallel line structured light to scan the identified pitting areas sequentially in the X and Y directions. After scanning, the z values ​​corresponding to the X and Y directions are extracted immediately, and the maximum value is taken as the depth measurement value of the pitting pit. This method is time-efficient and has a fast measurement speed.

[0063] Example 3

[0064] Based on the defect depth measurement system provided in Embodiment 2, the specific structure, function and application scenarios of the defect depth measurement system described in this embodiment of the present invention will be further explained below.

[0065] In this embodiment of the invention, the grating module includes a circular grating with at least two scales.

[0066] In one specific embodiment, the grating used for measurement has at least three scale levels. In this case, the grating module may include three circular gratings, each with a different scale level.

[0067] In one embodiment, the scales of the three circular gratings are 1 / 10, 1 / 50, and 1 / 100, respectively.

[0068] This invention features a grating projection structure with three levels, with line densities of 1 / 100, 1 / 50, and 1 / 10, respectively. The levels can be adjusted using buttons and knobs. The adjusted grating and structured light source are designed coaxially.

[0069] This invention discloses a system for measuring the depth of localized corrosion defects. The system employs a combination of two-dimensional imaging and unidirectional parallel-line structured light scanning, significantly reducing the computational load of three-dimensional imaging and dimensional measurement processes while improving the speed of pitting depth detection. Compared to traditional manual inspection or other machine vision inspection methods, this invention enhances the detection capability of three-dimensional defects on object surfaces, overcomes the influence of ambient light on defect detection, and eliminates the need for complete scanning and imaging of the entire test plane, saving multiple steps such as post-imaging point cloud editing, smoothing, stitching, and optimization, thus enabling rapid measurement of pitting. Furthermore, this invention can be widely applied to non-contact, non-destructive testing and measurement of corrosion defects in equipment in the petroleum and chemical industries, without requiring specific materials or environmental conditions, effectively improving the accuracy and efficiency of defect detection and automated testing.

[0070] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

[0071] In the description of this utility model, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In addition, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0072] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0073] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0074] The phrase "an embodiment" or "an embodiment" used in this specification means that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Therefore, the phrase "an embodiment" or "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0075] Although the embodiments disclosed in this utility model are as described above, the content is merely for the purpose of facilitating understanding of this utility model and is not intended to limit this utility model. Any person skilled in the art to which this utility model pertains may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this utility model; however, the scope of patent protection of this utility model shall still be determined by the scope defined in the appended claims.

Claims

1. A system for measuring the depth of localized corrosion defects, characterized in that, include: A grating module mounted on a fixed housing includes a measuring grating with adjustable grating scale. A structured light scanner, located above the grating module, is used to generate a structured light source that passes through the grating surface formed by the measuring grating so that the structured light source illuminates the measuring area containing pitting defects and scans the measuring area along at least two planar directions. The information processing module is used to obtain point cloud data in at least two planar directions to determine the depth of the target pitting defect.

2. The system of claim 1, wherein, The fixed housing is a cylindrical structure, and the measuring grating is a circular grating, which is installed on the radial section of the internal space of the cylindrical fixed housing.

3. The system of claim 2, wherein, The scale of the measuring grating is adjusted using a grating adjustment element located on the outer wall of the cylindrical fixed housing.

4. The system of claim 3, wherein, The grating module includes a circular grating with at least two scales.

5. The system of claim 4, wherein, The grating module includes three circular gratings with different scale levels, the scales of which are 1 / 10, 1 / 50, and 1 / 100 respectively.

6. The system according to any one of claims 2 to 5, characterized in that, The structured light scanner is located directly above the geometric center of the grating surface.

7. The system of claim 6, wherein, The bottom end of the cylindrical fixed housing is provided with an opening, and the top end of the cylindrical fixed housing is provided with a through hole, so that the structured light scanner is confined directly above the grating module by passing through the through hole.

8. The system of claim 7, wherein, The edge of the through hole also has a snap-fit ​​assembly for fixing the structured light scanner.

9. The system of claim 7 or 8, wherein, The system also includes: A two-dimensional image acquisition module is used to acquire images containing complete planar information of target pitting defects. The two-dimensional image acquisition module is equipped with a white light source to provide a light source for acquiring two-dimensional images.

10. The system of claim 9, wherein, The white light source is a ring-shaped white light source, wherein the ring-shaped white light source is installed on the ring-shaped area between the through hole in the top of the cylindrical fixed housing and the side wall of the fixed housing.

11. The system of any one of claims 1-5, wherein, The projection surface of the structured light source is parallel to the plane of the measurement area and the grating surface.

12. The system of any one of claims 1-5, wherein, The at least two planar directions are perpendicular to each other.

Images