In-situ welding repair method for cracks of titanium alloy casing support plate by laser

Abstract

The invention discloses a repair welding method, belongs to the technical field of case support plate crack repair, and particularly relates to an in-situ repair welding method for titanium alloy case support plate cracks through laser. Comprising the steps that crack detection and cleaning are conducted on the air inlet casing, a gas protection limiting tool is designed and installed, laser welding is adopted for repairing, nondestructive testing and size rechecking are conducted after repairing, and the tool comprises an anti-deformation sealing plate, a locking screw, a sealing plug device and an air inlet protection sealing device; the two anti-deformation sealing plates are installed on the upper face and the lower face of the air inlet casing correspondingly and fixed through the locking screws, the three sealing plug devices are connected with the air inlet casing, the air inlet protection sealing device is connected with the air inlet casing, accurate positioning and inert gas protection can be provided in the welding process, and oxidation and deformation are prevented. The method is high in repairing precision, small in heat affected zone, excellent in weld joint quality, suitable for crack repairing of the thin-wall welding assembly, and especially suitable for an air inlet casing made of a JG1101 material.

Description

Technical Field

[0001] This invention discloses a welding repair method, belonging to the field of crack repair technology for casing support plates, specifically involving a laser-based in-situ welding repair method for cracks in titanium alloy casing support plates. Background Technology

[0002] The intake casing typically consists of several parts, including the intake port, intake duct, internal components, and exhaust port. The intake port is the inlet to the intake casing and needs good aerodynamic performance to ensure stable and uniform airflow. The intake duct is the main body of the intake casing and needs sufficient strength and rigidity to withstand the impact and vibration of high-speed airflow. Internal components include the intake filter, regulating valve, and fuel injectors, which regulate and process the intake airflow to meet the engine's requirements under different operating conditions. The exhaust port is the outlet to the intake casing and needs to have certain aerodynamic performance to ensure smooth discharge of the intake air.

[0003] The main function of the intake casing is to prevent external impurities from entering the engine and to regulate the intake airflow to meet the engine's needs under different operating conditions. Specifically, the intake casing needs to have the following functions: 1. Air filtration: An air filter is installed inside the intake casing to filter out impurities and particulate matter in the air, ensuring the cleanliness of the engine interior.

[0004] 2. Adjusting intake airflow: The regulating valve and fuel injectors inside the intake casing can adjust and process the intake airflow to meet the engine's needs under different operating conditions.

[0005] 3. Reduce airflow noise: The internal structural design of the intake casing can reduce airflow noise, improving engine efficiency and comfort.

[0006] 4. Improve engine performance: The structure and design of the intake casing can improve engine performance and reliability, and reduce malfunctions and damage.

[0007] The air intake casing is a crucial component of an aero-engine, typically a thin-walled welded structure. It operates under high temperatures, high pressures, and vibration loads, making it prone to fatigue cracks. Traditional repair methods, such as argon arc welding and brazing, suffer from high heat input, severe deformation, and low repair precision. This is especially problematic for high-strength materials like JG1101, where repairs often result in secondary cracks or performance degradation.

[0008] Laser welding technology boasts advantages such as concentrated energy, a small heat-affected zone, and high precision, and is increasingly being applied to the repair of high-precision components. However, laser welding places extremely high demands on tooling positioning and gas protection, especially on complex curved surfaces. Insufficient protection can easily lead to defects such as oxidation and porosity. Therefore, there is an urgent need for a specialized tooling and process method suitable for repairing intake casing cracks. Summary of the Invention

[0009] Purpose of the invention: To provide a laser-based in-situ welding repair method for cracks in titanium alloy casing support plates, thereby solving the aforementioned problems.

[0010] Technical solution: A laser-assisted in-situ welding repair method for cracks in titanium alloy casing support plates, the welding repair method comprising: Step S1: Inspect, mark, and clean the intake casing for cracks; Step S2: Design and manufacture a gas protection limit fixture that matches the curved surface of the casing; Step S3: Install the tooling and ensure that the limit switch and the air circuit are sealed; Step S4: Repair the cracked area using laser welding technology; Step S5: Perform non-destructive testing and dimensional verification on the repaired area.

[0011] In a further embodiment, the crack detection includes at least one of penetrant testing, eddy current testing, or ultrasonic testing.

[0012] In a further embodiment, the gas protection limiting fixture includes a limiting module, a gas circuit system, and a sealing structure, wherein the limiting module conforms to the curved surface of the inner or outer wall of the casing.

[0013] In a further embodiment, the gas path system includes an inlet, an outlet, and a gas distribution chamber for providing inert gas protection during the welding process.

[0014] In a further embodiment, the parameters of the laser welding process include: laser power of 800-2000W, welding speed of 0.5-2m / min, spot diameter of 0.2-0.6mm, and shielding gas flow rate of 10-20L / min.

[0015] In a further embodiment, the protective gas is one or a mixture of argon and helium.

[0016] In a further embodiment, the nondestructive testing includes at least one of X-ray inspection, penetrant testing, or magnetic particle testing.

[0017] In a further embodiment, the nondestructive testing includes the following steps: S51. Preprocessing and 3D model registration; S52. Initial screening and localization of non-destructive testing based on eddy current or ultrasound; S53, Targeted X-ray fine inspection and 3D reconstruction; S54, Multimodal data fusion and defect quantification analysis algorithm; S55. Comprehensive quality assessment and report generation.

[0018] In a further embodiment, the gas protection limiting fixture includes: an anti-deformation sealing plate, a locking screw, a sealing plug device, and an air inlet protection sealing device; The anti-deformation sealing plate has two pieces, which are respectively installed on the upper and lower sides of the air intake casing and fixed by the locking screw. The sealing plug device has three sets and is connected to the air intake casing. The air intake protection sealing device is connected to the air intake casing.

[0019] The present invention has the following beneficial effects: 1. The tooling and the casing surface are perfectly aligned, with precise positioning to prevent misalignment during welding; 2. Integrated gas path system to achieve localized, efficient gas protection and prevent oxidation; 3. Laser welding has low heat input, reduces the heat-affected zone, and avoids degradation of the base material properties; 4. The repaired weld is of high quality, requiring minimal post-processing, thus saving time and costs; 5. Applicable to the repair of various thin-walled structural components, with strong versatility. Attached Figure Description

[0020] Figure 1 This is a flowchart of the method of the present invention.

[0021] Figure 2 This is a flowchart of the non-destructive testing method of the present invention.

[0022] Figure 3 This is a schematic diagram of the gas protection limiting tooling of the present invention.

[0023] Reference numerals: 1. Intake casing; 2. Anti-deformation sealing plate; 3. Locking screw; 4. Sealing plug device; 5. Intake protection sealing device. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0027] A laser-assisted in-situ welding repair method for cracks in titanium alloy casing support plates, such as... Figure 1 As shown, the welding repair method includes: Step S1: Inspect, mark, and clean the intake casing for cracks; Step S2: Design and manufacture a gas protection limit fixture that matches the curved surface of the casing; Step S3: Install the tooling and ensure that the limit switch and the air circuit are sealed; Step S4: Repair the cracked area using laser welding technology; Step S5: Perform non-destructive testing and dimensional verification on the repaired area.

[0028] Specifically, the repair process for cracks in the intake casing of a certain type of aircraft engine is as follows: Inspection and cleaning: Penetrant testing was used to confirm the location of the crack, the cracked area was cleaned by mechanical grinding, and a V-shaped bevel was prepared; Tooling design and processing: The tooling is designed based on the 3D scanning data, processed using 316 stainless steel, and integrated with argon gas path; Tooling installation: Secure the tooling to the inside of the housing with bolts and check for airtightness; Laser welding: using an IPG fiber laser, power 1200W, speed 1m / min, spot size 0.4mm, argon gas protection; Inspection: After welding, X-ray inspection and dimensional measurement are performed to confirm that there are no defects and the dimensions are qualified.

[0029] In one embodiment, the crack detection includes at least one of penetrant testing, eddy current testing, or ultrasonic testing.

[0030] In one embodiment, the gas protection limiting fixture includes a limiting module, a gas circuit system, and a sealing structure, wherein the limiting module conforms to the curved surface of the inner or outer wall of the casing.

[0031] In one embodiment, the gas path system includes an inlet, an outlet, and a gas distribution chamber for providing inert gas protection during the welding process.

[0032] In one embodiment, the parameters of the laser welding process include: laser power of 800-2000W, welding speed of 0.5-2m / min, spot diameter of 0.2-0.6mm, and shielding gas flow rate of 10-20L / min.

[0033] In one embodiment, the protective gas is one or a mixture of argon and helium.

[0034] In one embodiment, the nondestructive testing includes at least one of X-ray inspection, penetrant testing, or magnetic particle testing.

[0035] In one embodiment, such as Figure 2 As shown, the non-destructive testing includes the following steps: S51: Preprocessing and 3D Model Registration High-precision three-dimensional point cloud data of the repair area and surrounding area of ​​the intake casing to be inspected are obtained using a 3D laser scanner or structured light scanner.

[0036] Reconstruct the point cloud data into a triangular mesh patch model (STL format).

[0037] In computer-aided inspection (CAI) software, the reconstructed 3D model is automatically registered with the original CAD model of the intake casing to establish a precise coordinate system for the "virtual workpiece," providing a benchmark for subsequent robot path planning and inspection data mapping.

[0038] S52: Initial screening and localization of non-destructive testing based on eddy current or ultrasound Testing equipment: A multi-axis linkage industrial robot equipped with a high-frequency eddy current probe or a water immersion ultrasonic focusing probe is used.

[0039] Path planning: Based on the registration model established in S1, a dense rasterized scanning path is automatically generated on the surface of the repair area to ensure full coverage without omissions.

[0040] Automated scanning: The robot moves strictly according to the planned path, and the probe collects data at a constant height above the surface (or maintains a constant lift using laser ranging). The collected data includes: impedance (amplitude and phase) of eddy current signals or A-scan signals (amplitude-time) of ultrasound.

[0041] Data generation: The acquired signals are processed to generate a C-scan map (two-dimensional plane contour map) of the repaired area. For eddy currents, the C-scan map reflects changes in conductivity or impedance caused by defects; for ultrasound, the C-scan map reflects the amplitude of the defect echo at a specific depth.

[0042] Preliminary Defect Identification and Localization: By setting a threshold (e.g., signal-to-noise ratio SNR>3:1), the C-scan image is preliminarily analyzed to automatically identify abnormal signal regions (Regions of Interest, ROIs). The system records the precise center coordinates (X, Y) and approximate range of each ROI in the robot coordinate system (i.e., the registered CAD coordinate system).

[0043] S53: Targeted X-ray fine inspection and 3D reconstruction Inspection equipment: Employs a microfocus X-ray source and a flat panel detector, which are also held by an industrial robot, forming a dual-robot collaborative system (one robot holds the workpiece / X-ray source, and the other robot holds the detector) or a single robot drives the workpiece to rotate precisely on a turntable.

[0044] Targeted localization: Based on the ROI coordinate list provided in step S2, the system automatically plans the X-ray detection path. Instead of aimless imaging of the entire area, it precisely targets and irradiates each suspicious area. This greatly improves detection efficiency and reduces unnecessary radiation exposure.

[0045] Image Acquisition: For each ROI, data is acquired using computed tomography (CT) or digital radiography (DR) with multi-angle projection. For CT, the workpiece is rotated 360° or 180°+ fan-angle within the ROI area, acquiring hundreds to thousands of two-dimensional projection images. For DR, projections are taken at at least two different angles (e.g., 0° and 90° or ±45°).

[0046] 3D Reconstruction and Extraction: Filtered back-projection algorithms or iterative reconstruction algorithms (such as SART and SIRT algorithms) are applied to reconstruct the acquired projection images, obtaining local 3D CT volumetric data (Voxel Data) of the ROI region. This volumetric data clearly shows the true morphology of the defect in 3D space.

[0047] S54: Multimodal Data Fusion and Defect Quantification Analysis Algorithm This is the core innovation of the present invention: fusing and analyzing the preliminary data from S2 with the refined data from S3.

[0048] Data registration: The local 3D CT volume data reconstructed in S3 is accurately mapped to the corresponding position in the global 3D CAD model established in S1 through feature point matching or coordinate transformation.

[0049] Defect-accurate extraction algorithm: For 3D CT volume data, the region growing algorithm or level set algorithm is used for defect segmentation.

[0050] Region growth: Using points in the volume data whose gray values ​​are significantly different from those of the matrix material (e.g., pores are black with low gray values) as seed points, growth is performed within a 26-neighborhood according to a preset gray threshold range, until the entire connected defect region is traversed.

[0051] Level set: Treat the defect boundary as a zero level set function, and solve the partial differential equation to make the surface evolve to the position of the maximum image gradient (i.e. the defect edge), which can better handle defects with complex shapes.

[0052] 3D Defect Quantization: For each segmented defect entity, a series of quantization parameters are calculated: Volume: The number of voxels occupied by the defects is directly counted and multiplied by the physical volume of a single voxel.

[0053] Equivalent diameter: Calculate the diameter of a sphere with the same volume as the defect.

[0054] Morphology factor: (surface area * 2) / (4π * volume), used to determine the shape of defects. The closer to 1, the smoother (e.g., pores), and the larger the value, the more irregular (e.g., cracks, lack of fusion).

[0055] Thinnest cross-sectional dimension: Calculates the minimum span of the defect in different directions to assess its maximum weakening effect on structural strength.

[0056] Spatial location and depth: Accurately calculate the distance of the defect from the nearest surface.

[0057] Data fusion decision: The eddy current / ultrasonic signal characteristics (such as impedance change and echo amplitude) of the ROI in S2 are correlated with the three-dimensional quantization parameters of the defects extracted in S3. Machine learning algorithms (such as support vector machine SVM, random forest) or rule-based expert systems are used to automatically identify the defect type (such as porosity, cracks, and inclusions) and assess its hazard level.

[0058] S5: Comprehensive Quality Assessment and Report Generation The system automatically interprets all quantified defects based on preset acceptance criteria (such as NAS, ASTM, or self-developed enterprise standards).

[0059] The acceptance criteria are not just "present / absent", but a comprehensive evaluation based on multiple dimensions such as the type, size, quantity, location (whether in a high-stress area), and distribution density of defects.

[0060] Finally, the system generates an automated inspection report with pictures and text, including: the defect location highlighted on the 3D CAD model, a quantitative data table for each defect, a CT slice image of the defect, a 3D rendering, and the final pass / fail conclusion and recommendations (e.g., allow use, require secondary repair, scrap).

[0061] More specifically, this invention describes the specific process of nondestructive testing: S1: Secure the repaired casing to the inspection fixture. Scan the entire casing using a blue light scanner to obtain point cloud data. Register the point cloud with the casing's CAD model using an optimal fitting algorithm, achieving a registration accuracy better than 0.05mm.

[0062] S2: The robot holds an eddy current probe and scans the surface of the repair area with a grid resolution of 0.5mm x 0.5mm. The detection frequency is set to 2MHz to optimize the response to microcracks in the surface cladding layer. Impedance data is collected to generate a C-scan map. The algorithm automatically identifies three anomalous regions (ROI1, ROI2, ROI3) with a signal-to-noise ratio exceeding 4.0 and records their center coordinates.

[0063] S3: Transfer the receiver to the CT rotary stage. Based on the coordinates provided in S2, the system automatically controls the rotary stage to rotate ROI1 to the optimal magnification position between the X-ray source and the detector. Set the X-ray source voltage to 180kV and the current to 200μA. Perform a 360° rotation and acquire 1440 projection images. Apply the FDK filtered backprojection algorithm to reconstruct the three-dimensional volume data of the ROI1 region, with a voxel size of 20μm.

[0064] S4: Perform the following algorithm flow on the volume data of ROI1: Preprocessing: Nonlocal mean filtering algorithm is used to reduce image noise while preserving edges.

[0065] Segmentation: Using the region growing algorithm, with a grayscale threshold range of [0, 12000] (background is 0, substrate material grayscale is about 30000), three independent defect entities were successfully segmented.

[0066] Quantification: Calculate parameters for each defect. Take the largest Defect #1 as an example: volume = 0.015 mm³, equivalent diameter = 0.30 mm, shape factor = 1.2 (approx. spherical), thickness at the thinnest part = 0.25 mm, and the closest distance to the surface = 0.80 mm. Considering its spherical shape and high gray-scale contrast, the algorithm determines it as a pore.

[0067] Fusion: Review the eddy current signal at this position in S2, which shows a weak phase shift, consistent with the characteristics of a pore. According to the preset acceptance criteria (an equivalent diameter of a single pore < 0.4 mm is acceptable), Defect #1 is determined to be qualified.

[0068] S5: Repeat S3 and S4 for ROI2 and ROI3. ROI2 is determined to be a small inclusion with a qualified size. After CT inspection of ROI3, it is found that its eddy current anomaly is actually a pseudo-signal caused by a geometric structure mutation and is not a real defect, so it is excluded.

[0069] The system automatically generates a report with the conclusion that the quality of the repaired area of the intake casing meets the acceptance criteria and is approved for release.

[0070] Compared with the prior art, the non-destructive testing of the present invention has the following remarkable advantages: Comprehensive and accurate: Combining the high sensitivity of eddy current / ultrasound to surface / subsurface defects with the intuitive three-dimensional visualization ability of X-ray CT for internal defects, it realizes "no dead angle" detection of defects in the repaired area.

[0071] Efficient and targeted: Using the preliminary screening results to guide the refined inspection, making the time-consuming CT inspection only target suspicious areas, the overall inspection efficiency is increased by more than 50%, and the radiation dose is significantly reduced.

[0072] Objective quantification: Through advanced image processing algorithms, convert defects from abstract image signals into precise three-dimensional quantification parameters, eliminating the influence of human subjective factors, and the judgment results are consistent and reliable.

[0073] Intelligent decision-making: Adopting data fusion and machine learning algorithms, it can not only detect defects, but also automatically identify the types of defects and evaluate their risks, providing in-depth decision-making support for engineers.

[0074] Digital twin: All detection data are associated with the CAD model, forming a "quality digital twin" of the repaired casing, providing valuable data assets for full life cycle management.

[0075] In one embodiment, as Figure 3 shown, the gas protection limit tooling includes: an anti-deformation sealing plate, a locking screw, a sealing plug device, and an intake protection sealing device; The anti-deformation sealing plate has two pieces, which are respectively installed on the upper and lower sides of the air intake casing and fixed by the locking screw. The sealing plug device has three sets and is connected to the air intake casing. The air intake protection sealing device is connected to the air intake casing.

[0076] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for in-situ laser welding repair of cracks in titanium alloy casing support plates, characterized in that, The welding repair method includes: Step S1: Inspect, mark, and clean the intake casing for cracks; Step S2: Design and manufacture a gas protection limit fixture that matches the curved surface of the casing; Step S3: Install the tooling and ensure that the limit switch and the air circuit are sealed; Step S4: Repair the cracked area using laser welding technology; Step S5: Perform non-destructive testing and dimensional verification on the repaired area.

2. The laser-assisted in-situ welding repair method for cracks in titanium alloy casing support plates according to claim 1, characterized in that, The crack detection includes at least one of penetrant testing, eddy current testing, or ultrasonic testing.

3. The laser-assisted in-situ welding repair method for cracks in titanium alloy casing support plates according to claim 1, characterized in that, The gas protection limiting fixture includes a limiting module, a gas circuit system, and a sealing structure. The limiting module is fitted to the curved surface of the inner or outer wall of the casing.

4. The laser-assisted in-situ welding repair method for cracks in titanium alloy casing support plates according to claim 1, characterized in that, The gas path system includes an inlet, an outlet, and a gas distribution chamber, which are used to provide inert gas protection during the welding process.

5. The laser-assisted in-situ welding repair method for cracks in titanium alloy casing support plates according to claim 1, characterized in that, The parameters of the laser welding process include: laser power 800-2000W, welding speed 0.5-2m / min, spot diameter 0.2-0.6mm, and shielding gas flow rate 10-20L / min.

6. The laser-assisted in-situ welding repair method for cracks in titanium alloy casing support plates according to claim 5, characterized in that, The protective gas is one or a mixture of argon and helium.

7. The laser-assisted in-situ welding repair method for cracks in titanium alloy casing support plates according to claim 1, characterized in that, The non-destructive testing includes at least one of X-ray inspection, penetrant testing, or magnetic particle testing.

8. The laser-assisted in-situ welding repair method for cracks in titanium alloy casing support plates according to claim 7, characterized in that, The non-destructive testing includes the following steps: S51. Preprocessing and 3D model registration; S52. Initial screening and localization of non-destructive testing based on eddy current or ultrasound; S53, Targeted X-ray fine inspection and 3D reconstruction; S54, Multimodal data fusion and defect quantification analysis algorithm; S55. Comprehensive quality assessment and report generation.

9. The laser-assisted in-situ welding repair method for cracks in titanium alloy casing support plates according to claim 1, characterized in that, The gas protection limit fixture includes: an anti-deformation sealing plate, a locking screw, a sealing plug device, and an air inlet protection sealing device; The anti-deformation sealing plate has two pieces, which are respectively installed on the upper and lower sides of the air intake casing and fixed by the locking screw. The sealing plug device has three sets and is connected to the air intake casing. The air intake protection sealing device is connected to the air intake casing.

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