Positioning device and method for roller eddy current detection micro-damage part

Abstract

The invention discloses a positioning device and method for a roller eddy current testing micro-damage part, and belongs to the technical field of roller nondestructive testing. The positioning device comprises a positioning frame, a reference marking assembly and an angle distance adjusting mechanism; wherein the positioning frame is used for being aligned with a to-be-detected area on the surface of a roller, the reference mark assembly is arranged on the positioning frame and used for forming recognizable reference mark points in eddy current detection, and the angle distance adjusting mechanism is installed at the reference position of the positioning frame. And the marking module is used for accurately marking according to the calculated azimuth angle of the slightly damaged part relative to the reference position and the actual distance. Stable and recognizable reference mark points are formed on the positioning frame through the reference mark assembly, the positioning precision is improved to the millimeter level from the centimeter level in the prior art in combination with a geometric transformation algorithm, the entity position of a slightly damaged part can be accurately locked, accurate sampling target points are provided for subsequent metallographic analysis, and the accuracy of metallographic analysis is improved. And errors and resource waste caused by blind sampling are avoided.

Description

Technical Field

[0001] This invention relates to the field of non-destructive testing technology for rolls, and in particular to a positioning device and method for eddy current testing of micro-damaged parts of rolls. Background Technology

[0002] As a core component in metallurgical steel rolling production, the surface quality of rolling rolls directly determines the dimensional accuracy, surface finish, and internal quality of rolled products. The service condition of rolling rolls directly affects the operating efficiency and product qualification rate of the entire production line. During long-term service, rolling rolls must withstand complex alternating loads, severe thermal shocks, continuous rolling forces, and high-speed friction and wear with the workpiece, which makes their surfaces prone to micro-cracks, soft spots, spalling, oxide scale, and other minor damage (hereinafter collectively referred to as micro-damaged areas).

[0003] These micro-damaged areas are typically on the micrometer to millimeter scale, making them difficult to identify with the naked eye, but they pose a significant threat: if not detected and properly addressed in time, these micro-damaged areas will rapidly expand during subsequent rolling processes, causing serious malfunctions such as localized roll breakage and large-area spalling. This not only leads to the scrapping of the roll but may also cause production interruptions, resulting in substantial economic losses for the company. Furthermore, the nature of the micro-damaged areas (such as crack depth, soft spot hardness, and degree of oxidation) directly determines the roll repair plan; therefore, accurately determining the nature of the micro-damage is a crucial step in roll maintenance.

[0004] Eddy current testing technology has become one of the mainstream technologies for detecting surface defects in rolls due to its advantages such as fast detection speed, high sensitivity, no need for coupling agent, and non-contact detection. However, existing eddy current testing technology has significant technical bottlenecks, making it difficult to meet the precise positioning requirements in actual production: Eddy current testing systems can only generate planar unfolded diagrams or three-dimensional schematic diagrams of the roll, and can only provide the approximate area of ​​the minor damage (usually with an error of several centimeters to tens of centimeters). They cannot accurately map the minor damage signals in the test diagram to the actual surface of the roll, making it impossible for inspectors to directly locate the specific location of the minor damage.

[0005] Since the micro-damaged parts are invisible to the naked eye, conventional auxiliary methods such as surface wave detection and penetrant detection are also difficult to accurately identify their specific locations. This leads to the need to grind the surface of the roll over a large area during subsequent metallographic analysis sampling, which not only results in low sampling efficiency but also causes excessive wear on the roll and shortens its service life. If the sampling position is inaccurate, it will also lead to distorted metallographic analysis results and make it impossible to accurately determine the nature of the micro-damage.

[0006] Therefore, developing a simple, easy-to-operate, and highly accurate method to achieve precise correlation between micro-destructive signals and physical locations, and to provide accurate sampling locations for metallographic analysis, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0007] To address the technical problems of traditional eddy current testing's inability to accurately locate the physical surface of a roll and the difficulty in sampling for metallographic analysis, this invention provides a positioning device and method for micro-damage areas in eddy current testing of rolls. This device precisely maps abnormal signals from the eddy current test image onto the actual surface of the roll. Through magnetic powder paste imaging and geometric relationship calculations, the precise location of the micro-damage is calibrated. This provides an accurate sampling location for subsequent metallographic testing, facilitating accurate determination of the nature of the micro-damage and avoiding resource waste caused by indiscriminate grinding.

[0008] The technical solution adopted by the positioning device and method for detecting micro-damage parts of rolls using eddy current detection in this invention is as follows: A positioning device for micro-damaged parts in eddy current testing of rolls includes a positioning frame, a reference mark assembly, and an angle and distance adjustment mechanism. The positioning frame is used to align the area to be tested on the roll surface. The reference mark assembly is set on the positioning frame to form identifiable reference mark points during eddy current testing. The angle and distance adjustment mechanism is installed at the reference position of the positioning frame to accurately mark the micro-damaged parts based on the calculated azimuth angle and actual distance of the micro-damaged parts relative to the reference position.

[0009] A further improvement of the technical solution of the present invention is that the positioning frame is a polygonal frame structure and the material of the positioning frame is non-magnetic metal.

[0010] A further improvement of the technical solution of the present invention is that: the reference position of the positioning frame is the geometric center of the positioning frame, the edge of the positioning frame is provided with scale markings and positioning structure, which are used to make the edge of the positioning frame parallel to the axis of the roll or at a preset angle, and the back of the positioning frame is provided with a fixing component.

[0011] A further improvement of the technical solution of the present invention is that: the reference mark assembly includes multiple reference mark units, which are evenly distributed in the edge area of ​​the positioning frame; each reference mark unit is a through hole opened on the positioning frame, the through hole is filled with magnetic powder marker, and a wear-resistant coating is provided in the through hole.

[0012] A further improvement of the technical solution of the present invention is that: the number of reference mark units is four, which are respectively set at the four corners of the positioning frame, the inner diameter of the through hole is 4-6mm, and the magnetic powder mark is magnetic powder paste conforming to GB / T-15822 standard.

[0013] A further improvement of the technical solution of the present invention is that: the angle distance adjustment mechanism includes an angle adjustment component for adjusting the direction of the mark to the azimuth angle; wherein, the angle adjustment component includes a pointer that can rotate 360°, and the pointer is provided with a guide structure for guiding the application of the mark.

[0014] A further improvement of the technical solution of the present invention is that: the guide structure is a longitudinal gap opened in the middle of the pointer, the width of the longitudinal gap is 1.5-2.5mm, and at the same time, scale lines are set on the pointer along the length direction of the pointer.

[0015] A method for locating micro-damaged parts in eddy current detection of rolling mill rolls includes the following steps: S1. Based on the roll inspection map generated by the eddy current detection system, determine the approximate area of ​​the minor damage part; S2. Install the positioning device in the general area and form reference marker points using the reference marker assembly; S3. Start the eddy current testing system for re-inspection and obtain the test image containing the reference marker points and the micro-damage signal; S4. Based on the relative positional relationship between the micro-damage signal and the reference marker in the detection image, calculate the azimuth angle and actual distance of the micro-damage part relative to the reference position of the positioning frame through geometric transformation; S5. Adjust to the azimuth angle using the angle and distance adjustment mechanism, and mark along the azimuth angle according to the actual distance to obtain the physical location of the micro-damaged part; S6. Eddy current re-inspection: Mark the physical location of the obtained micro-damage area with magnetic paste. When the eddy current abnormality display of the micro-damage area is covered by the marked magnetic paste signal, it indicates that the marking is accurate.

[0016] A further improvement of the above technical solution of the present invention is that: in step S4, the geometric transformation includes a coordinate system rotation and translation model and a scaling conversion. The actual distance calculation formula is: d=d0 / S0*S, where d0 is the pixel distance between the micro-loss signal and the reference position in the detection image, S0 is the distance between the two horizontally displayed magnetic powder markers in the detection image, and S is the actual distance between the two horizontal through holes.

[0017] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows: This invention forms stable and identifiable reference marker points on the positioning frame through a reference marker component. Combined with a geometric transformation algorithm, it establishes a precise mapping relationship between the coordinates of the eddy current detection map and the coordinates of the roll entity, improving the positioning accuracy from the centimeter level of existing technologies to the millimeter level. It can accurately lock the physical position of the micro-damaged parts, providing accurate sampling targets for subsequent metallographic analysis and avoiding errors and resource waste caused by blind sampling.

[0018] This invention combines the high sensitivity of eddy current detection with the intuitiveness of magnetic particle imaging. Eddy current detection is responsible for efficiently capturing micro-damage signals, while magnetic particle marking is responsible for providing a stable reference and clear physical markings. The two work together to ensure the effective identification of micro-damage signals and achieve accurate calibration of physical positions, thereby improving the reliability of detection and positioning. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a positioning device for detecting micro-damage parts of a roll using eddy current detection according to the present invention; Figure 2 This is a schematic diagram of the pointer structure of a positioning device for detecting minor damage in roll eddy currents, according to the present invention.

[0020] In the attached diagram: 1. Positioning bracket; 2. Through hole; 3. Pointer; 4. Gap. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of this invention.

[0022] like Figure 1-2 As shown, this embodiment provides a positioning device for detecting minor damage in roll eddy currents, including a positioning frame 1, a reference mark assembly, and an angle and distance adjustment mechanism.

[0023] In this embodiment, the positioning frame 1 adopts a polygonal frame structure, preferably a square frame, and is made of non-magnetic metal, which will not cause magnetic interference to the eddy current detection field. The side length of the frame is designed to be 100mm (which can be flexibly adjusted to 80mm or 120mm according to the curvature of the roll surface: 80mm for small diameter rolls and 120mm for large diameter rolls), and the thickness of the frame is 6mm.

[0024] The positioning frame 1 has a fixing component on its back. In this embodiment, the fixing component can be a vacuum adsorption component located at the geometric center of the positioning frame 1, which fixes the positioning frame 1 to the roll.

[0025] In this embodiment, the reference marking assembly includes four reference marking units, which are evenly distributed at the four corners of the square positioning frame 1. Each reference marking unit is a through hole 2 opened on the positioning frame 1. The inner diameter of the through hole 2 is 5mm, and the through hole 2 is filled with magnetic powder marking material. The inner wall of the through hole 2 is smoothed to facilitate the filling of magnetic powder marking material and subsequent cleaning.

[0026] The magnetic powder markers filling the through hole 2 can be high-resolution magnetic powder paste conforming to the GB / T-15822-2005 standard for magnetic particle testing. This magnetic powder paste has good adhesion and anti-detachment properties and will not easily fall off or spread during the roll rotation and eddy current testing process.

[0027] In this embodiment, the angle distance adjustment mechanism is installed at the geometric center of the positioning frame 1. The angle distance adjustment mechanism includes an angle adjustment component for adjusting the direction of the mark to the azimuth angle. The angle adjustment component includes a pointer 3 that can rotate 360°. The pointer 3 is made of stainless steel, and a longitudinal gap 4 with a width of 2mm is opened in the middle of the pointer 3 along its length direction to guide the application of magnetic powder paste and ensure the straightness and accuracy of the mark. At the same time, scale lines are engraved on the pointer 3 along its length direction.

[0028] Example 2 This embodiment provides a method for locating micro-damaged parts in eddy current detection of rolling mill rolls, including the following steps: S1. Preliminary positioning: Based on the roll 3D inspection image generated by the eddy current detection system, the approximate area of ​​suspected soft spot signals is determined through the system's built-in coordinate positioning function.

[0029] S2. Installation of positioning equipment and formation of reference marks: Use a lint-free cloth soaked in anhydrous ethanol to wipe the approximate area of ​​the initial positioning and the surface of the roll within a 50mm radius around it to remove grinding fluid residue, iron filings, dust, oxide scale and other contaminants; after wiping, let it air dry for 5 minutes to ensure that there is no residual liquid on the surface; attach Example 1 to the approximate area of ​​the roll surface and firmly fix Example 1 with the fixing components on the back; fill the through holes 2 at the four corners of the positioning frame 1 with high-resolution magnetic powder paste to form four uniform and clear reference marks, which are marked as points A, B, C and D respectively.

[0030] S3. Eddy Current Re-inspection and Image Acquisition: Start the eddy current detection system, set the re-inspection parameters to be consistent with the initial inspection, drive the roll to rotate slowly, and simultaneously control the eddy current probe to move at a constant speed along the roll axis to perform a full-coverage scan of the area where Example 1 is located, acquiring a two-dimensional detection image containing four reference marker points A, B, C, and D, and the soft spot micro-loss signal (denoted as point P). This detection image must clearly show the signal peak value and the contour of the micro-loss signal at each reference marker point to ensure the accuracy of subsequent measurements.

[0031] S4. Geometric Calculation and Parameter Determination: Open the detection image obtained in S3 using image analysis software (such as ImageJ). Establish a two-dimensional rectangular coordinate system with the geometric center O of the positioning frame as the origin, where the X-axis is parallel to one set of opposite sides of the positioning frame, and the Y-axis is parallel to another set of opposite sides. Use the distance measurement tool of the image analysis software to measure the pixel distance between the micro-damage signal point P in the detection image and the four reference marker points A, B, C, and D. Measure the angle between the line connecting point P and the origin O and the positive direction of the X-axis. Calculate the azimuth angle and actual distance of the micro-damage part relative to the reference position of the positioning frame through geometric transformation.

[0032] S5. Precise marking: Adjust the angle to the included angle in S4 through the angle and distance adjustment mechanism, and then find the position obtained according to step S4 through the longitudinal gap 4 in the middle of the pointer 3. Apply magnetic powder paste to this position. This marking point is the calculated physical position of the micro-damaged part.

[0033] S6. Eddy current re-inspection: Mark the physical location of the obtained micro-damage area with magnetic powder paste. When the eddy current abnormality display of the micro-damage area is covered by the marked magnetic powder paste signal, it indicates that the marking is accurate. Prepare a sample at the marked location, take pictures with a metallographic microscope on site, and perform metallographic analysis.

[0034] In the above embodiments, a positioning device and method for eddy current detection of micro-damaged parts in rolls are provided. This invention forms stable and identifiable reference marker points on the positioning frame using a reference marker component. Combined with a geometric transformation algorithm, a precise mapping relationship is established between the coordinates of the eddy current detection image and the coordinates of the roll entity, improving the positioning accuracy from the centimeter level of existing technologies to the millimeter level. This enables precise locking of the physical location of the micro-damaged parts, providing accurate sampling targets for subsequent metallographic analysis and avoiding errors and resource waste caused by blind sampling. This invention combines the high sensitivity of eddy current detection with the intuitiveness of magnetic particle imaging. Eddy current detection efficiently captures micro-damaged signals, while magnetic particle marking provides a stable reference and clear physical markers. Their synergistic effect ensures effective identification of micro-damaged signals and achieves precise calibration of the physical location, improving the reliability of detection and positioning.

[0035] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the inventive concept should fall within the protection scope of the present invention. All technical contents for which protection is sought in this invention are fully described in the claims.

Claims

1. A positioning device for detecting minor damage in roll eddy currents, characterized in that: It includes a positioning frame (1), a reference mark assembly and an angle and distance adjustment mechanism; wherein, the positioning frame (1) is used to align the area to be inspected on the surface of the roll, the reference mark assembly is set on the positioning frame (1) and is used to form identifiable reference mark points in eddy current detection, and the angle and distance adjustment mechanism is installed at the reference position of the positioning frame (1) and is used to accurately mark the area based on the calculated azimuth angle and actual distance of the micro-damaged part relative to the reference position.

2. The positioning device for detecting micro-damage parts in eddy current testing of rolls according to claim 1, characterized in that: The positioning frame (1) is a polygonal frame structure, and the material of the positioning frame (1) is non-magnetic metal.

3. A positioning device for detecting micro-damaged areas of a roll by eddy current according to claim 1, wherein: The reference position of the positioning frame (1) is the geometric center of the positioning frame (1). The edge of the positioning frame (1) is provided with scale markings and positioning structures to make the edge of the positioning frame (1) parallel to the axis of the roll or at a preset angle. The back of the positioning frame (1) is provided with fixing components.

4. A positioning device for detecting micro-damaged areas of a roll by eddy current according to claim 1, wherein: The reference marking assembly includes multiple reference marking units, which are evenly distributed in the edge area of ​​the positioning frame (1); each reference marking unit is a through hole (2) opened on the positioning frame (1), the through hole (2) is filled with magnetic powder marking material, and the through hole (2) is provided with a wear-resistant coating.

5. A device for locating microdamage sites in a roll for eddy current testing according to claim 4, characterized in that: The number of reference marking units is four, which are respectively set at the four corners of the positioning frame (1). The inner diameter of the through hole (2) is 4-6mm, and the magnetic powder marking material is magnetic powder paste conforming to GB / T-15822 standard.

6. A positioning device for detecting micro-damaged areas of a roll by eddy current according to claim 1, wherein: The angle distance adjustment mechanism includes an angle adjustment component for adjusting the direction of the marker to the azimuth angle; wherein, the angle adjustment component includes a pointer (3) that can rotate 360°, and the pointer (3) has a guide structure for guiding the application of the marker.

7. A positioning device for detecting micro-damaged areas of a roll by eddy current according to claim 1, wherein: The guide structure is a longitudinal gap (4) opened in the middle of the pointer (3), the width of the longitudinal gap (4) is 1.5-2.5mm, and at the same time, the pointer (3) is provided with scale lines along the length direction of the pointer (3).

8. A method for positioning a micro defect site of a rolling mill roll by eddy current testing, characterized by Using the positioning device according to any one of claims 1-7 includes the following steps: S1. Based on the roll inspection map generated by the eddy current detection system, determine the approximate area of ​​the minor damage part; S2. Install the positioning device in the general area and form reference marker points using the reference marker assembly; S3. Start the eddy current testing system for re-inspection and obtain the test image containing the reference marker points and the micro-damage signal; S4. Based on the relative positional relationship between the micro-damage signal and the reference marker in the detection image, calculate the azimuth angle and actual distance of the micro-damage part relative to the reference position of the positioning frame (1) through geometric transformation; S5. Adjust to the azimuth angle using the angle and distance adjustment mechanism, and mark along the azimuth angle at the actual distance to obtain the physical location of the micro-damaged part; S6. Eddy current re-inspection: Mark the physical location of the obtained micro-damage area with magnetic paste. When the eddy current abnormality display of the micro-damage area is covered by the marked magnetic paste signal, it indicates that the marking is accurate.

9. A method for locating micro-damaged parts in eddy current detection of rolls according to claim 8, characterized in that: In step S4, the geometric transformation includes a coordinate system rotation and translation model and a scaling conversion. The actual distance calculation formula is: d=d0 / S0*S, where d0 is the pixel distance between the micro-loss signal in the detection image and the reference position, S0 is the distance between the two horizontally displayed magnetic powder markers in the detection image, and S is the actual distance between the two horizontal through holes (2).

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