A device and method for repairing cracks in nickel-based single crystal turbine blades

Abstract

The present invention provides a device and method for repairing cracks in a nickel-based single-crystal turbine blade. The device comprises a laser cladding device, a low-temperature circulating liquid cooling device, and a blade clamping device. The laser cladding device comprises a laser, a laser cladding head, a robotic arm, a powder feeder, and an argon gas bottle. The laser cladding head is mounted at the end of the robotic arm, the laser cladding head is connected to the laser, the powder feeder is connected to the laser cladding head, and the argon gas bottle is connected to the powder feeder. The low-temperature circulating liquid cooling device comprises a circulating cooler and a cooling box, the cooling box is connected to the circulating cooler, and the blade clamping device is fixed within the cooling box. The present invention precisely controls the morphology of the molten pool and its solidification conditions during the laser cladding repair of cracks in a single-crystal turbine blade, promotes the epitaxial growth of columnar dendrites, and enables a complete single-crystal structure to be obtained in the repair area, thereby achieving the repair of cracks in the nickel-based single-crystal turbine blade and ensuring the service performance of the repaired blade.

Description

Technical Field

[0001] The present invention relates to the technical field of laser additive repair and remanufacturing, and in particular to a device and method for repairing cracks in a nickel-based single crystal turbine blade. Background Art

[0002] Nickel-based single-crystal turbine blades are used in advanced aircraft engines to improve operating temperatures and thrust-to-weight ratios. The microstructure of nickel-based single-crystal turbine blades features directional columnar dendrites growing along the blade body, resulting in an overall single-grain structure. This complex manufacturing process results in low yields, leading to high prices. Over extended service life under harsh operating conditions of high temperature, high pressure, and high stress, single-crystal turbine blades often develop defects such as tip wear, thermal barrier coating delamination, and ablation, which reduce aircraft engine performance and even endanger operational safety. Longitudinal cracks in single-crystal turbine blades are the most detrimental, severely reducing their service life and leading to premature replacement. This significantly increases aircraft engine maintenance and operating costs, while also reducing aircraft readiness. Repairing cracks in nickel-based single-crystal turbine blades, allowing them to be reused, not only extends their service life, conserves valuable metal materials, but also reduces aircraft engine maintenance costs, generating significant economic benefits.

[0003] Currently, there are a variety of process methods for blade repair, including arc welding, electron beam welding and laser cladding. The repair process steps mainly include: blade cleaning, defect measurement, defect repair, machining allowance and polishing inspection. Among them, laser cladding technology has the greatest potential. Laser cladding technology uses a high-energy laser beam to form a tiny molten pool in a local area, thereby achieving near-net-shape repair of single-crystal blades. However, for the repair of blade cracks in single-crystal turbine blades, laser cladding repair often faces the problem of inconsistent orientation between the laser beam and the blade, and the epitaxial growth direction of the columnar crystals in the molten pool is difficult to accurately control. The repair area often forms grains with disordered orientation, making it difficult to obtain a single crystal structure, resulting in repair failure. How to control the molten pool solidification conditions during the laser cladding repair of nickel-based single-crystal turbine blade cracks so that the repair area is continuous and complete with epitaxial columnar dendrites that are consistent with the orientation of the substrate is the key technical bottleneck for the successful laser cladding repair of nickel-based single-crystal turbine blade cracks. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for repairing cracks in a nickel-based single-crystal turbine blade body, accurately control the morphology of the molten pool and its solidification conditions during laser cladding repair of cracks in a single-crystal turbine blade body, promote the epitaxial growth of columnar dendrites, so that a complete single crystal structure can be obtained in the repair area, thereby realizing the repair of cracks in a nickel-based single-crystal turbine blade body and ensuring the service performance of the blade after repair.

[0005] According to one object of the present invention, the present invention provides a device for repairing cracks in a nickel-based single-crystal turbine blade, comprising a laser cladding device, a low-temperature circulating liquid cooling device and a blade clamping device, wherein the laser cladding device comprises a laser, a laser cladding head, a robotic arm, a powder feeder and an argon gas bottle, wherein the laser cladding head is mounted at the end of the robotic arm, the laser cladding head is connected to the laser, the powder feeder is connected to the laser cladding head, and the argon gas bottle is connected to the powder feeder; the low-temperature circulating liquid cooling device comprises a circulating cooler and a cooling box, the cooling box is connected to the circulating cooler, and the blade clamping device is fixed in the cooling box.

[0006] Furthermore, the laser, the powder feeder and the robotic arm are respectively connected to a computer.

[0007] Furthermore, the laser cladding head is in an initial posture vertically downward.

[0008] Furthermore, the powder feeder contains nickel-based single crystal powder material.

[0009] Furthermore, the argon gas cylinder is filled with 99.999% high-purity argon gas.

[0010] Furthermore, the cooling box is provided with a liquid inlet and a liquid outlet, and the liquid inlet and the liquid outlet of the cooling box are respectively connected to the circulating cooler through pipelines.

[0011] Furthermore, the output power of the laser is 0-1000W, the diameter of the laser is 0.5mm-2mm, the modulated pulse output frequency of the laser is 0-50Hz, the duty cycle of the laser is 15%-100%, the moving speed is 0-10mm / s, and the coaxial powder feeding rate is 1 g / min.

[0012] Furthermore, the temperature of the coolant in the low-temperature circulating liquid cooling device is -30°C±10°C, and the continuous flow rate of the coolant is 0-10 L / min.

[0013] According to another object of the present invention, the present invention provides a method for repairing cracks in a nickel-based single crystal turbine blade, comprising the following steps:

[0014] S1, laser cladding repair of nickel-based single-crystal turbine blades. Before repairing blade cracks, the blades are polished to remove thermal barrier coating materials, rust, and oil stains, and then ultrasonically cleaned and cleaned with acetone.

[0015] S2, detect cracks on the blade body and perform slight beveling on the cracks;

[0016] S3, after the blade clamping device fastens the single crystal turbine blade, the nickel-based single crystal turbine blade to be repaired is clamped on the low-temperature circulating cooling device; the lower end of the blade is immersed in the low-temperature coolant to continuously provide cooling to the blade;

[0017] S4, adjusting the clamping posture of the nickel-based single crystal turbine blade, maintaining the angle between the nickel-based single crystal turbine blade and the laser cladding head within the range of 0-45°, and aligning the focus of the laser cladding to the starting position of the crack repair, that is, the lowest point of the single crystal blade blade crack;

[0018] S5, the low-temperature circulating liquid cooling device circulates the output of low-temperature coolant and starts laser repair;

[0019] S6, according to the distribution of the crack, the repair path of the laser cladding head is formulated, and the repair path gradually moves from the starting position of the crack, that is, the lowest point, to the highest point of the crack;

[0020] S7: During the repair process, the laser cladding head periodically swings around the laser focus in a backward posture, thereby changing the morphology of the molten pool and the crystal growth behavior on the solidification interface. After the laser repair process is completed, the crack repair area of ​​the nickel-based single crystal turbine blade is lightly polished to remove the excess, and the entire repair process is finally completed.

[0021] Furthermore, in S2, the depth of the groove is 1 / 4-1 / 2 of the thickness of the blade body, and the ratio of the groove width to the groove depth is 0.8:1.0; in S7, the angle range of the laser cladding head swing is 1°-10°, and the frequency of the periodic swing is 0-20 times / minute.

[0022] The technical solution of the present invention couples the control of laser cladding process parameters, the angle between the laser cladding head and the blade body, and the auxiliary temperature gradient to regulate the process parameters, thereby precisely controlling the morphology of the molten pool and its solidification conditions during the laser cladding repair of single-crystal turbine blade body cracks, promoting the epitaxial growth of columnar dendrites, so that a complete single crystal structure can be obtained in the repair area, thereby realizing the repair of nickel-based single-crystal turbine blade body cracks and ensuring the service performance of the repaired blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 It is a structural diagram of an embodiment of the present invention;

[0025] Figure 2 Schematic diagram of the machined groove of a crack in a single crystal blade according to an embodiment of the present invention;

[0026] Figure 3 It is a schematic diagram of the structure of the embodiment of the present invention when used;

[0027] Figure 4 It is another structural diagram when the embodiment of the present invention is used.

[0028] In the figure, 1. Laser, 2. Laser cladding head, 3. Robotic arm, 4. Computer, 5. Powder feeder, 6. Argon cylinder, 7. Circulating cooler, 8. Cooling box, 9. Liquid inlet, 10. Liquid outlet, 11. Blade clamping device, 12. Single crystal turbine blade, 13. Crack. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as limiting the present invention.

[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a communication between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0032] Example 1

[0033] like Figures 1-4 As shown,

[0034] A device for repairing cracks in a nickel-based single-crystal turbine blade body includes a laser cladding device, a low-temperature circulating liquid cooling device, and a blade clamping device. The laser cladding device includes a laser 1, a laser cladding head 2, a robotic arm 3, a computer 4, a powder feeder 5, and a matching argon gas cylinder 6. The laser 1, the powder feeder 5, and the robotic arm 3 are respectively connected to the computer 4, which controls the operation of each component of the entire device.

[0035] The laser cladding head 2 is mounted on the end of a robotic arm 3, which drives the laser cladding head 2 to move and maintain the laser cladding head 2 in an initial vertically downward position. In this embodiment, the initial position of the laser cladding head 2 is vertical, that is, the laser cladding head 2 maintains a vertically downward position.

[0036] The powder feeder 5 is connected to the laser cladding head 2, and the argon bottle 6 is connected to the powder feeder 5. The powder feeder 5 is filled with powder material used for laser cladding. The powder material selected for laser cladding in this embodiment is the same as the material of the nickel-based single crystal blade to be repaired. High-purity argon (99.999%) is used to protect the laser cladding repair process, and the pure argon is stored in the argon bottle 6.

[0037] The laser cladding head 2 is connected to the laser 1. In this embodiment, the output power of the laser 1 is 0-1000W. The diameter of the laser spot is adjusted according to the width of the crack, generally ranging from 0.5mm to 2mm. The pulse output frequency of the laser modulation is 0-50Hz, the duty cycle is 15%-100%, the movement speed is 0-10mm / s, and the coaxial powder feeding rate is 1g / min.

[0038] The low-temperature circulating liquid cooling device includes a circulating cooler 7 and a cooling box 8. The cooling box 8 is provided with a liquid inlet 9 and a liquid outlet 10. The liquid inlet 9 and the liquid outlet 10 of the cooling box 8 are respectively connected to the circulating cooler 7 through pipelines. The coolant prepared by the circulating cooler 7 circulates continuously in the cooling box 8.

[0039] The coolant used in the low-temperature circulating liquid cooling device is a single liquid substance such as ethanol, ethylene glycol, water, etc., or a mixture of multiple liquids.

[0040] The blade clamping device 11 is fixed in the cooling box 8. The blade can be clamped by the blade clamping device 11. The low-temperature circulating liquid cooling device can continuously cool the coolant to -30℃±10℃ and circulate it into the blade clamping device 11 with a continuous flow rate of 0-10L / min.

[0041] The present invention provides a method for repairing cracks in a nickel-based single crystal turbine blade, comprising the following steps:

[0042] Before starting laser cladding to repair the cracks on the blade body of the nickel-based single-crystal turbine blade, the blade body of the single-crystal turbine blade is polished to remove the thermal barrier coating material and possible rust and oil stains, and is then ultrasonically cleaned and cleaned with acetone.

[0043] Next, the crack 13 of the blade body is detected and the crack is slightly beveled using machining methods including CNC milling, such as Figure 2 The depth of the groove is 1 / 4-1 / 2 of the blade body thickness, and the ratio of the groove width to the groove depth is 0.8:1.0, which is between 1mm and 2mm.

[0044] After the blade clamping device 11 fastens the single crystal turbine blade 12, the nickel-based single crystal turbine blade to be repaired is clamped on the low-temperature circulating cooling device. The lower end of the blade is immersed in the low-temperature coolant, thereby continuously cooling the blade.

[0045] Adjust the clamping posture of the nickel-based single crystal turbine blade to ensure that the angle between the nickel-based single crystal turbine blade and the laser cladding head 2 is kept in the range of 0-45°, and the focus of the laser cladding is aligned with the starting position of the crack repair (i.e., the lowest point of the single crystal blade crack), as shown in the figure. Figure 3 and Figure 4 shown.

[0046] The low-temperature circulating cooling pump begins circulating low-temperature coolant at a flow rate of 0-10L / min. Laser repair begins when the blade temperature of the nickel-based single-crystal turbine blade drops to a certain temperature, typically below zero, such as -20°C.

[0047] Based on the distribution of the cracks, a repair path for laser cladding head 2 is developed. This repair path typically moves from the crack's starting point (lowest point) to the crack's highest point. Laser 1 output power is 0-1000W, and the spot diameter is adjusted based on the crack width, typically between 0.5mm and 2mm. The laser modulation pulse output frequency is 0-50Hz, the duty cycle is 15%-100%, the travel speed is 0-10mm / s, and the coaxial powder feed rate is 1g / min.

[0048] During the repair process, the laser cladding head 2 periodically oscillates around the laser focal point in a backward-tilted position, altering the molten pool morphology and the crystal growth behavior at the solidification interface. The oscillation angle ranges from 1° to 10°, with a frequency of 0-20 cycles per minute. After the laser repair process is complete, the cracked area of ​​the nickel-based single-crystal turbine blade is lightly polished to remove excess material, completing the repair process.

[0049] The present invention couples and controls the laser cladding process parameters, the angle between the cladding head and the blade body, and the auxiliary temperature gradient to regulate the process parameters, thereby accurately controlling the morphology of the molten pool and its solidification conditions during the laser cladding repair of single-crystal turbine blade body cracks, promoting the epitaxial growth of columnar dendrites, so that a complete single crystal structure can be obtained in the repair area, thereby realizing the repair of nickel-based single-crystal turbine blade body cracks and ensuring the service performance of the repaired blade.

[0050] The present invention solves the key technical bottleneck that currently makes it difficult to repair cracks in single-crystal turbine blades, and achieves a completely single-crystal structure in the repair area; it has a simple structure, is easy to adjust, and uses a digitalized process, which is conducive to reducing labor and achieving automation, and has good robustness; the process method has good versatility and can be conveniently used to repair other similar single-crystal / oriented-crystal parts or structural components.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for repairing cracks in a nickel-based single crystal turbine blade, characterized in that: The steps include: S1, laser cladding repair of nickel-based single crystal turbine blades. Before repairing the blade cracks, the blades of the nickel-based single crystal turbine blades are polished to remove thermal barrier coating materials, rust and oil stains, and then ultrasonically cleaned and cleaned with acetone. S2, detect cracks on the blade body of nickel-based single crystal turbine blades and perform groove processing on the cracks; the groove depth is 1 / 4-1 / 2 of the blade body thickness, and the ratio of groove width to groove depth is 0.8:1.0; S3, after the blade clamping device has fastened the nickel-based single-crystal turbine blade, the nickel-based single-crystal turbine blade to be repaired is clamped on a low-temperature circulating cooling device; the lower end of the nickel-based single-crystal turbine blade is immersed in a low-temperature coolant to continuously cool the nickel-based single-crystal turbine blade; the low-temperature circulating cooling device includes a circulating cooler and a cooling box, the cooling box is connected to the circulating cooler, and the blade clamping device is fixed in the cooling box; S4, adjusting the clamping posture of the nickel-based single crystal turbine blade, maintaining the angle between the nickel-based single crystal turbine blade and the laser cladding head within the range of 0-45°, and aligning the focus of the laser cladding to the starting position of the crack repair, that is, the lowest point of the crack on the nickel-based single crystal turbine blade; S5, the low-temperature circulating cooling device circulates and outputs low-temperature coolant, and laser repair begins; the temperature of the coolant in the low-temperature circulating cooling device is -30℃±10℃, and the continuous flow rate of the coolant is 0-10L / min; S6, according to the distribution of the crack, the repair path of the laser cladding head is formulated, and the repair path gradually moves from the starting position of the crack, that is, the lowest point, to the highest point of the crack; During the repair process, the laser cladding head periodically oscillates in a backward-leaning position around the laser focus, thereby changing the morphology of the molten pool and the crystal growth behavior on the solidification interface. After the laser repair process is completed, the crack repair area of ​​the nickel-based single-crystal turbine blade is lightly polished to remove the excess, completing the entire repair process. The laser cladding head oscillates at an angle of 1°-10° and at a frequency of 0-20 times / minute.

2. The method for repairing cracks in a nickel-based single crystal turbine blade according to claim 1, characterized in that: The output power of the laser is 0-1000W, the diameter of the laser is 0.5mm-2mm, the modulated pulse output frequency of the laser is 0-50Hz, the duty cycle of the laser is 15%-100%, the moving speed is 0-10mm / s, and the coaxial powder feeding rate is 1 g / min.

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