Method and processing tool for repairing wear of an aeroengine aluminium alloy blade

Abstract

The application discloses a kind of repair method and processing tool for aero-engine aluminum alloy blade wear, belong to aero-engine maintenance process technical field.It provides a kind of repair method and processing tool that can effectively carry out additive repair to wear serious aluminum alloy blade.The repair method is first repaired the two end journal parts of aero-engine aluminum alloy blade wear by at least twice laser melting additive repair procedure, then each journal is mechanically integrated to specified size, then it is rounded and nondestructive testing, finally, vibration fatigue test is carried out on the aero-engine aluminum alloy blade that passes detection to complete the repair work, wherein the parameter requirement of vibration fatigue test is σ-1=80MPa, 300Hz, and the cycle is 1x107.The processing tool includes support connection assembly, support frame and fixed structure, and the aero-engine aluminum alloy blade is detachably arranged on the support frame through the fixed structure, and the support frame is fixed to the machining center through the support connection assembly.

Description

Technical Field

[0001] This invention relates to a repair method, and more particularly to a repair method for worn aluminum alloy blades in aero-engines, belonging to the field of aero-engine repair and maintenance technology. This invention also relates to a machining fixture for the aforementioned repair method. Background Technology

[0002] Aluminum alloys, due to their low hardness, light weight, and high strength, are widely used in the manufacture of adjustable blades for aero-engine intake casings. During operation, the repeated relative motion of the blades under pressure causes journal wear, and dimensional deviations lead to the decommissioning of numerous blades. Traditional welding processes for repairing aluminum alloy blades result in significant deformation and low weld strength, while spray coating repairs suffer from low bonding strength and are prone to detachment. Therefore, blade repair requires the purchase of a large number of new blades for replacement, resulting in high repair costs. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for repairing wear of aluminum alloy blades for aero-engines that can effectively perform additive repair on severely worn aluminum alloy blades, and a machining tooling for the repair method.

[0004] The technical solution adopted to solve the above-mentioned technical problems is: a repair method for worn aluminum alloy blades of aero-engines. The repair method first repairs the worn journal ends of the aero-engine aluminum alloy blades through at least two laser melting additive repair processes. Then, each journal is machined to the specified dimensions. Next, it is rounded and subjected to non-destructive testing. Finally, the qualified aero-engine aluminum alloy blades undergo vibration fatigue testing to complete the repair work.

[0005] The parameters for the vibration fatigue test are σ-1 = 80 MPa, 300 Hz, and 1 × 10⁷ cycles.

[0006] Furthermore, before performing laser additive repair, comparative experiments were conducted to determine that the repair material used in laser additive repair was 2A14 aluminum alloy powder.

[0007] The preferred method described above is to first use machining fixtures to set pin holes on the journals at both ends of the aero-engine aluminum alloy blades on a machining center before repairing the worn journals. This provides a positioning reference for the subsequent machining after laser additive repair.

[0008] The runout of the ejector pin holes on both ends of the journal is less than 0.005 mm.

[0009] Furthermore, during laser melting additive repair, the subsequent repair pass of two adjacent additive repair passes is performed after the journal surface repaired in the previous repair pass has cooled. During each repair pass, an inclined laser head is used to add aluminum alloy material to achieve overlapping coverage at the rounded corners of the blade journal.

[0010] The preferred method for the above scheme is as follows: laser power 2100W; powder feeding rate 2g / min; scanning speed 5mm / s; defocusing amount -1mm; protective gas flow rate 17L / min; powder feeding gas flow rate 6L / min.

[0011] Furthermore, during the overall machining process, the surface to be repaired by additive manufacturing is turned and ground to the dimensions shown in the drawing using a lathe and a grinding machine respectively with top clamping. The allowable deviation of the surface is no more than 0.02 mm, and the surface roughness is Ra0.8.

[0012] A machining fixture for the repair method, the machining fixture comprising a support connection assembly, a support frame and a fixing structure, wherein the aero-engine aluminum alloy blade is detachably arranged on the support frame via the fixing structure, and the support frame is detachably fixed to the machining center via the support connection assembly.

[0013] Furthermore, the support connection assembly includes a clamping outer cylindrical shaft, which is fixedly connected to the support frame via its top end.

[0014] In a preferred embodiment of the above solution, the support frame includes a U-shaped support frame, the fixing structure is arranged at the top of the two vertical sides of the U-shaped support frame, and the U-shaped support frame is supported at the top of the clamping outer cylindrical shaft by its horizontal side.

[0015] Furthermore, the fixing structure includes fixing grooves provided at the top of the two vertical sides of the U-shaped support frame and two sets of fixing components. Each set of fixing components includes at least one hinge screw and a set of clamping blocks. The clamping blocks in each set are movably hinged to the top of the corresponding vertical side of the U-shaped support frame by the corresponding hinge screws.

[0016] The two journals of the aero-engine aluminum alloy blade are respectively fixed in corresponding grooves and, with the cooperation of corresponding clamping blocks, are detachably fixed on the U-shaped support frame with the inner surface of the vertical edge where the large end of the aero-engine aluminum alloy blade is located as the reference.

[0017] The beneficial effects of this invention are as follows: The technical solution provided in this application first repairs the worn end journals of the aero-engine aluminum alloy blades through at least two laser melting additive repair processes. Then, each journal is machined to the specified dimensions using machinery. Next, it is rounded and non-destructive tested. Finally, the qualified aero-engine aluminum alloy blades are subjected to a vibration fatigue test to complete the repair work. The parameters for the vibration fatigue test are σ-1 = 80 MPa, 300 Hz, and 1 × 10⁷ cycles. This solves the technical problems of large deformation and low weld strength when using fusion welding to repair aluminum alloy blades in the prior art, and low bonding strength and easy detachment when using spraying. The aluminum alloy blades modified using the technical solution provided in this application not only ensure the bonding strength at the repair site but also have small deformation, which can effectively reduce the blade downtime rate. Furthermore, the overall machining by machinery with tooling can ensure that the dimensions of the repaired blades meet the requirements of relevant standards. Attached Figure Description

[0018] Figure 1 This is a front view of the machining tooling of the present invention;

[0019] Figure 2 for Figure 1 Side view.

[0020] The components in the diagram are labeled as follows: 1. Support connection assembly; 2. Support frame; 3. Fixing structure; 4. Vertical side; 5. Horizontal side; 6. Fixing groove; 7. Fixing component; 8. Hinge screw; 9. Clamping block; 10. Aluminum alloy blade of aircraft engine; 11. Journal; 12. Inner surface of vertical side. Detailed Implementation

[0021] like Figure 1 , Figure 2 The invention illustrates a method for effectively repairing severely worn aluminum alloy blades in aero-engines using additive manufacturing, along with a machining fixture for the repair method. The repair method first repairs the worn journal ends of the aero-engine aluminum alloy blade through at least two laser melting additive manufacturing processes. Then, each journal is machined to the specified dimensions. Next, it is rounded and subjected to non-destructive testing. Finally, the qualified aero-engine aluminum alloy blade undergoes a vibration fatigue test to complete the repair work.

[0022] The vibration fatigue test parameters are required to be σ₁ = 80 MPa, 300 Hz, and 1 × 10⁷ cycles. The machining fixture includes a support connection assembly 1, a support frame 2, and a fixing structure 3. The aero-engine aluminum alloy blade is detachably mounted on the support frame 2 via the fixing structure 3, and the support frame 2 is fixed to the machining center via the support connection assembly 1. The technical solution provided in this application first repairs the worn journal ends of the aero-engine aluminum alloy blade through at least two laser melting additive repair processes. Then, each journal is machined to the specified dimensions, followed by rounding and non-destructive testing. Finally, a vibration fatigue test is performed on the qualified aero-engine aluminum alloy blade to complete the repair work. The vibration fatigue test parameters are required to be σ₁ = 80 MPa, 300 Hz, and 1 × 10⁷ cycles. This solves the technical problems of large deformation and low weld strength when repairing aluminum alloy blades using fusion welding, and low bonding strength and easy detachment when using spraying. The aluminum alloy blade modified with the technical solution provided in this application not only ensures the bonding strength of the repaired area, but also has small deformation, which can effectively reduce the downtime rate of the blade. Furthermore, the overall processing by machinery with the help of tooling can also ensure that the shape and size of the repaired blade meet the requirements of relevant standards.

[0023] In the above embodiments, in order to improve the bonding strength between the additive part and the substrate in laser additive repair, and to ensure that the dimensional and positional dimensions meet the requirements during processing, this application first determines through comparative experiments that the repair material used in laser additive repair is 2A14 aluminum alloy powder. Correspondingly, before repairing the worn journal portion of the aero-engine aluminum alloy blade, a machining fixture is used to set pin holes on the journals at both ends of the aero-engine aluminum alloy blade on a machining center, providing a positioning reference for the subsequent machining after laser additive repair. The runout of the pin holes on the journals at both ends is less than 0.005 mm. At this time, the support connection assembly 1 in the above machining fixture includes a clamping outer cylindrical shaft, which is fixedly connected to the support frame 2 through its top end. The support frame 2 includes a U-shaped support frame, and the fixing structure 3 is arranged on the top of the two vertical sides 4 of the U-shaped support frame. The U-shaped support frame is supported on the top end of the clamping outer cylindrical shaft through its horizontal side 5. The fixing structure 3 includes fixing grooves 6 and two sets of fixing components 7, each set of fixing components 7 including at least one hinge screw 8 and a set of clamping blocks 9. Each set of clamping blocks 9 is movably hinged to the top of the corresponding vertical side 4 of the U-shaped support frame by the corresponding hinge screw 8. The two journals 11 of the aero-engine aluminum alloy blade 10 are detachably fixed to the U-shaped support frame by the corresponding fixing grooves 6 and the corresponding clamping blocks 9, with the inner surface 12 of the vertical side where the large end of the aero-engine aluminum alloy blade is located as the reference. In this way, during the overall machining, the surface of the additive repair can be turned and ground to the drawing size by using a lathe and a grinding machine with top clamping method. The allowable deviation of the surface is no more than 0.02mm, and the surface roughness is Ra0.8.

[0024] Accordingly, as part of laser additive repair, in this application, during laser melting additive repair, the subsequent repair pass of two adjacent additive repair passes is performed after the journal surface repaired in the previous repair pass has cooled. During each repair pass, an inclined laser head is used to add aluminum alloy material, achieving overlapping coverage at the rounded corners of the blade journal. The parameters for laser additive repair are: laser power 2100W; powder feed rate 2g / min; scanning speed 5mm / s; defocusing amount -1mm; protective gas flow rate 17L / min; powder feed gas flow rate 6L / min.

[0025] In summary, by adopting the technical solution provided in this application, and fully utilizing the mature technology of laser additive aluminum alloy manufacturing, combined with its high strength and small deformation characteristics, the phenomenon of blade downtime caused by uneven wear can be eliminated, increasing the blade repair rate to 100% and saving approximately 2,000 yuan in repair costs per blade. Furthermore, repairing aluminum alloy blades using this process can shorten the overall repair cycle from approximately one month to half a month, significantly improving repair efficiency, enhancing blade repair quality, and reducing downtime and scrap rates. Specific Implementation

[0027] The purpose of this application is to eliminate the current situation where blades are out of service due to wear and dimensional deviations in the blade journal. It provides a laser additive repair method for worn aluminum alloy blade journals in aero-engines, improving repair quality and reducing blade repair costs.

[0028] The technical solution of this application is as follows:

[0029] Step 1: Powder Selection and Sample Verification Before Repair (including tensile testing, metallographic testing, and hardness testing). In principle, the powder selected should be of the same or similar grade as the base material (2A70 forged aluminum) or have better performance. Since journal wear is mainly affected by surface roughness and material hardness, and roughness is primarily ensured through machining, we selected aluminum alloy powders of the same series, such as 2024 and 2A14, as well as hard alloy powders with higher hardness, such as AlSi10Mg and HSAl-6, for comparative testing. Additive manufacturing effect analysis, combined with metallographic, tensile strength, and additive manufacturing effect factors, showed that 2A14 had the best overall performance. Therefore, 2A14 aluminum alloy powder was selected for laser additive repair.

[0030] Step 2: Design a special tooling for alignment and machine-install pin holes. The tooling design should be based on the actual structural characteristics of the part to rigidly constrain the risk dimensions, control the deformation to a minimum, and ensure that the adjustment at both ends of the journal is less than 0.005mm.

[0031] Step 3: Using laser additive manufacturing technology, a single layer of additive manufacturing is applied to the journal surface. After cooling, additive manufacturing is performed again to reduce the heat-affected zone. Since aluminum alloy has a low absorption rate for 1064nm YAG laser light, an inclined laser cladding head is used to additively manufacture the aluminum alloy material, overlapping and covering the inverted radius of the adjustable blade journal, thus achieving additive repair of the worn area of ​​the journal. Parameter settings: Laser power 2100W; powder feed rate 2g / min; scanning speed 5mm / s; defocusing amount -1mm; protective gas flow rate 17L / min; powder feed gas flow rate 6L / min.

[0032] Step 4: Perform turning and external cylindrical grinding on the additive surface to restore the dimensions shown in the drawing. The allowable deviation is no more than 0.02 mm, and the surface roughness is Ra 0.8.

[0033] Step 5: Use clamps to round off the blade, smoothing the transition area between the journal and the blade.

[0034] Step 6: Perform non-destructive testing on the blades (fluorescent or X-ray inspection) to check for cracks.

[0035] Step 7: Take the repaired parts and conduct a vibration fatigue test at σ-1 = 80MPa, 300Hz, and 1×107 cycles. After passing the test, the parts can be put into use.

[0036] After loading the fixture into the machining center chuck, install the matching plug at the large end. Then load the pressure block onto the fixture, placing a 0.5-2mm shim between the pressure block and the fixture. Do not load any parts in this step. Flatten surface A of the fixture, then enlarge the holes at both the large and small ends ΦB. After loading the blade into the fixture, machine the center holes at both ends according to the drawing. After the fixture is corrected, the fixture should be disassembled only after each batch of parts has been machined. Local defects are disregarded during runout inspection, and the large end plug must not be loosened.

Claims

1. A method for repairing wear on aluminum alloy blades of aero engines, characterized in that: The repair method first repairs the worn journal ends of the aero-engine aluminum alloy blade through at least two laser melting additive repair processes. Then, each journal is machined to the specified dimensions. Next, it is rounded and non-destructive tested. Finally, the qualified aero-engine aluminum alloy blade is subjected to a vibration fatigue test to complete the repair work. Among them, the parameter requirements for vibration fatigue testing are σ -1 80 MPa, 300 Hz, 1 × 10⁻⁶ cycles 7 , During laser melting additive repair, the subsequent repair pass is performed after the journal surface repaired in the previous pass has cooled. Each repair pass uses a tilted laser head to add aluminum alloy material, achieving overlapping coverage at the rounded corners of the blade journal. The parameters for laser melting additive repair are as follows: laser power 2100 W; powder feed rate 2 g / min; scanning speed 5 mm / s; defocusing amount -1 mm; protective gas flow rate 17 L / min; powder feed gas flow rate 6 L / min. During the overall machining process, the surface of the additive repair is turned and ground to the dimensions shown in the drawing using both a lathe and a grinding machine with a clamping method. The allowable deviation of the machined surface is no more than 0.02 mm, and the surface roughness is Ra0.

8.

2. The repair method for worn aluminum alloy blades of aero-engines according to claim 1, characterized in that: Before performing laser melting additive repair, comparative experiments were conducted to determine that the repair material used in laser melting additive repair was 2A14 aluminum alloy powder.

3. The repair method for worn aluminum alloy blades of aero engines according to claim 1 or 2, characterized in that: Before repairing the worn journal sections of the aero-engine aluminum alloy blades, a machining fixture is used to set pin holes on the journals at both ends of the aero-engine aluminum alloy blades on a machining center. This provides a positioning reference for the subsequent overall mechanical machining after laser melting additive repair is completed. The runout of the ejector pin holes on both ends of the journal is less than 0.005 mm.

4. The repair method for worn aluminum alloy blades of aero-engines according to claim 3, characterized in that: The machining fixture includes a support connection assembly (1), a support frame (2), and a fixing structure (3). The aero-engine aluminum alloy blade is detachably arranged on the support frame (2) through the fixing structure (3). The support frame (2) is detachably fixed to the machining center through the support connection assembly (1).

5. The repair method for worn aluminum alloy blades of aero engines according to claim 4, characterized in that: The support connection assembly (1) includes a clamping outer cylindrical shaft, which is fixedly connected to the support frame (2) through its top end.

6. The repair method for worn aluminum alloy blades of aero-engines according to claim 5, characterized in that: The support frame (2) includes a U-shaped support frame, the fixing structure (3) is arranged on the top of the two vertical sides (4) of the U-shaped support frame, and the U-shaped support frame is supported on the top of the clamping outer cylindrical shaft by its horizontal side (5).

7. The repair method for worn aluminum alloy blades of aero-engines according to claim 6, characterized in that: The fixing structure (3) includes fixing grooves (6) set on the top of the two vertical sides of the U-shaped support frame and two sets of fixing components (7). Each set of fixing components (7) includes at least one hinge screw (8) and a set of clamping blocks (9). Each set of clamping blocks (9) is movably hinged to the top of the corresponding vertical side (4) of the U-shaped support frame by the corresponding hinge screw (8).

Images