An additive repair method for clutch drive shaft platform based on laser cladding technology

Abstract

This invention discloses an additive repair method for a clutch drive shaft platform based on laser cladding technology, comprising: preheating the clutch drive shaft and Fe-5 iron-based powder before welding; using Fe-5 iron-based powder to perform laser melting additive manufacturing on the worn area of ​​the clutch drive shaft with no machining allowance; and subjecting the laser-melted additively manufactured clutch drive shaft to slow cooling after welding and supplementary machining, thus completing the clutch drive shaft repair. This invention transforms subtractive repair into additive repair, selecting Fe-5 iron-based powder as the additive repair powder, so that after laser cladding, its surface hardness reaches or exceeds that of the original carburized substrate surface, allowing direct cladding on the original clutch drive shaft platform, restoring the clutch drive shaft, which cannot be repaired by grinding, to its original process level. Simultaneously, the wear resistance of the repaired platform is verified through fretting wear testing.

Description

Technical Field

[0001] This invention belongs to the field of additive repair technology for remanufacturing of aerospace transmission equipment. More specifically, this invention relates to an additive repair method for a clutch drive shaft platform based on laser cladding technology. Background Technology

[0002] The M17 series helicopter engine is connected to the main gearbox using a roller-type free-travel clutch. This type of clutch is a commonly used one-way power transmission mechanism, its function being to allow the engine to drive the rotor without the rotor driving the engine. When the engine is stopped or the helicopter is in autorotation mode, it ensures that the rotor is disengaged from the engine, allowing the rotor to rotate freely. For helicopters with multiple engines, the shutdown of any one engine will not affect the operation of the other engines and rotor. Figure 1 As shown, due to the impact during startup and the fretting wear during use, indentations and wear appear at the contact point between the clutch rollers and the clutch drive shaft. When the wear exceeds the process specifications, it will reduce the transmission performance of the clutch and thus affect flight safety.

[0003] For clutch drive shaft platforms with excessive wear, grinding the platform has been a long-standing solution during repairs. However, for main reducers that have undergone multiple overhauls, the drive shaft platform dimensions are nearing their lower limit, making further grinding impossible. Therefore, there is an urgent need to explore a reasonable additive manufacturing method to repair platforms that have been repaired multiple times and have no grinding margin left. Summary of the Invention

[0004] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0005] To achieve these and other advantages according to the present invention, an additive repair method for a clutch drive shaft platform based on laser cladding technology is provided, comprising the following steps: Step 1: Preheat the clutch drive shaft and Fe-5 iron-based powder before welding; Step 2: Using Fe-5 iron-based powder, laser melting additive manufacturing is performed on the worn area of ​​the clutch drive shaft where there is no machining allowance; Step 3: After laser melting additive manufacturing, the clutch drive shaft is slowly cooled after welding and further processed to complete the clutch drive shaft repair.

[0006] Preferably, in step one, the specific method for preheating the clutch drive shaft before welding includes: heating the clutch drive shaft in the furnace to 100℃~150℃ and holding it at that temperature for 30 minutes; The specific method for preheating Fe-5 iron-based powder before welding includes: placing Fe-5 iron-based powder in a powder feeding tank, heating it to 100℃~150℃ with the tank, and holding it at that temperature for 30 minutes.

[0007] Preferably, in step two, the Fe-5 iron-based powder comprises, by mass percentage: 0.40-0.45% C powder, 13-15% Cr powder, 0.3-0.6% Si powder, 0.15-0.30% Mn powder, and the balance being Fe powder.

[0008] Preferably, in step two, the hardness of the Fe-5 iron-based powder is 62HRC~67HRC.

[0009] Preferably, in step two, when performing laser melting additive manufacturing on the worn area of ​​the clutch drive shaft with no machining allowance, the laser power is set to 300~400W, the scanning speed is 6~8mm / s, the powder trough width is 6mm, the powder feeding rate is 0.20~0.40 rpm, the track spacing is 0.35~0.5mm, the single layer height is 0.4mm, and the single track width is 0.7~1mm.

[0010] Preferably, in step two, when laser melting additive manufacturing is performed on the worn area of ​​the clutch drive shaft, the effective additive depth is no more than 0.15 mm, and the thickness of a single laser cladding layer is 0.3~0.5 mm.

[0011] Preferably, in step three, the specific method for slow cooling of the clutch drive shaft after welding includes: placing the clutch drive shaft in an electric oven at a temperature of 130℃~150℃ after welding, keeping it warm for 2 hours, turning off the oven power, and cooling it with the oven.

[0012] Preferably, in step three, after the laser-melted additive manufacturing of the clutch drive shaft is slow-cooled after welding, it also includes machining and shaping.

[0013] Preferably, in step three, after the clutch drive shaft repair is completed, the pressure calculation is performed on the unrepaired clutch drive shaft and the repaired clutch drive shaft to determine whether the surface strength of the additive location of the repaired clutch drive shaft meets the usage requirements.

[0014] Preferably, the specific method for performing pressure calculations on the unrepaired clutch drive shaft includes: S1. Calculate the load F acting on the clutch drive shaft of a single-engine unit: F = P / v in, P For single-engine power,P = W / t , t For time, W To do work for the engine; v For the engine linear velocity, v = πDn , n Engine speed, D This is the circumference of the contact point between the engine and the clutch drive shaft; The clutch drive shaft comprises 16 platforms, and the load on each platform is... F 1= F / 16; S2. Calculate the pressure applied to the clutch drive shaft. p 1: p 1= F 1 / S in, p 1 represents the pressure exerted by a single engine on the clutch drive shaft. S S = (This is the contact area between the engine and the clutch drive shaft.) l × b , l This refers to the contact length between the engine and the clutch drive shaft. b The contact width between the engine and the clutch drive shaft, where , R This represents the equivalent radius of curvature, i.e., the roller radius. l Indicates the effective length of the roller. E * This represents the combined elastic modulus of the cylindrical roller in contact with the clutch platform, where, , E 1. E 2 represents the elastic modulus of the roller and clutch drive shaft platform, respectively. v 1. v 2 represents the Poisson's ratio of the roller and the clutch drive shaft, respectively; The specific method for performing pressure calculations on the repaired clutch drive shaft includes: setting a test load. F 2. Apply load to the repaired cladding layer, based on the area of ​​the crater. S 2. Calculation F 2. Pressure failure test pressure under test load p 2, that is p 2= F 2 / S 2; like p 2≥ p 1. The surface strength of the additive location of the repaired clutch drive shaft meets the usage requirements.

[0015] The present invention has at least the following beneficial effects: The present invention proposes an additive repair method based on laser cladding technology, which restores a platform that cannot be repaired by grinding to its original process level, thereby achieving the goal of reducing costs and increasing efficiency. At the same time, the wear resistance of the repaired platform is verified by fretting wear test.

[0016] This invention improves the repair process of the clutch drive shaft platform, transforming subtractive repair into additive repair, which aligns with the remanufacturing repair concept. It restores scrapped parts with no machining margin to the original technical level through additive repair, thereby reducing costs, increasing efficiency, and achieving sustainable development.

[0017] Based on the material and operating conditions of the drive shaft, this invention selects Fe-5 iron-based powder as the additive repair powder, so that after laser cladding, its surface hardness reaches or exceeds that of the original carburized surface of the substrate, and can be directly clad on the original clutch drive shaft platform, simplifying the process.

[0018] Because the additive material is relatively small and a symmetrical alternating cladding method is used, deformation is easier to control. After the excess material is removed by machining after cladding, there is no need to consider additional chemical or heat treatment, which will not affect the original infiltrated layer. At the same time, its micro-motion wear resistance meets the requirements for use.

[0019] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the wear of the clutch drive shaft platform; Figure 2 This is a schematic diagram of the additive repair method for the clutch drive shaft platform based on laser cladding technology according to the present invention. Figure 3 A schematic diagram of the cladding test piece being fabricated; Figure 4 This is a 200X metallographic image of a section of a cladding specimen after laser cladding according to the method in Example 1. Figure 5 This is a 200X metallographic image of a section of a cladding specimen after laser cladding according to the method in Example 1. Figure 6 This is a 200X metallographic image of a section of a cladding specimen after laser cladding according to the method in Example 1. Figure 7 A 200X magnified image of the destructive force test of the cladding specimen under a 5kg load. Figure 8 A 200X magnified image of the destructive force test of the cladding specimen under a 10kg load. Figure 9 A 200X magnified image of the destructive force test of the cladding specimen under a 20kg load. Figure 10 A 200X magnified image of the destructive force test of the cladding specimen under a 60kg load. Figure 11 1000X magnified image of the destructive force test of the central area of ​​the cladding specimen under a 60kg load; Figure 12 1000X magnified image of the destructive force test of 60kg load on the edge area of ​​the cladding specimen. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0022] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof. Example 1 like Figure 2 As shown, this embodiment provides an additive repair method for a clutch drive shaft platform based on laser cladding technology, including the following steps: Step 1: Heat the clutch drive shaft to 150℃ in the furnace and hold for 30 minutes; place Fe-5 iron-based powder in a powder feeding jar and heat it to 150℃ in the jar, and hold for 30 minutes; wherein, the Fe-5 iron-based powder comprises, by mass percentage: 0.45% C powder, 15% Cr powder, 0.6% Si powder, 0.3% Mn powder, and the balance being Fe powder; Step 2: Set the laser power to 400W, scanning speed to 6mm / s, powder trough width to 6mm, powder feeding rate to 0.40 rpm, track spacing to 0.5mm, single layer height to 0.4mm, and single track width to 1mm, and perform laser melting additive manufacturing on the clutch drive shaft platform with no machining allowance. Step 3: After laser cladding is completed, place the clutch drive shaft in an electric oven at 150℃ and keep it warm for 2 hours. Then turn off the oven power and let it cool with the oven. The clutch drive shaft platform repair is now complete.

[0023] In this embodiment, the thickness of a single laser cladding layer is approximately 0.5 mm, while the effective additive depth requirement is no greater than 0.15 mm. This embodiment has sufficient processing allowance to meet production and processing requirements, so single-layer cladding can fully meet the repair requirements.

[0024] Example 2 An additive repair method for a clutch drive shaft platform based on laser cladding technology includes the following steps: Step 1: Heat the clutch drive shaft to 150℃ in the furnace and hold for 30 minutes; place Fe-5 iron-based powder in a powder feeding jar and heat it to 150℃ in the jar, and hold for 30 minutes; wherein, the Fe-5 iron-based powder comprises, by mass percentage: 0.45% C powder, 15% Cr powder, 0.6% Si powder, 0.3% Mn powder, and the balance being Fe powder; Step 2: Set the laser power to 300W, scanning speed to 8mm / s, powder trough width to 6mm, powder feeding rate to 0.20 rpm, track spacing to 0.35mm, single layer height to 0.3mm, and single track width to 0.7mm, and perform laser melting additive manufacturing on the clutch drive shaft platform with no machining allowance. Step 3: After laser cladding is completed, place the clutch drive shaft in an electric oven at 150℃ and keep it warm for 2 hours. Then turn off the oven power and let it cool with the oven. The clutch drive shaft platform repair is now complete.

[0025] Example 3 An additive repair method for a clutch drive shaft platform based on laser cladding technology includes the following steps: Step 1: Heat the clutch drive shaft to 150℃ in the furnace and hold for 30 minutes; place Fe-5 iron-based powder in a powder feeding jar and heat it to 150℃ in the jar, and hold for 30 minutes; wherein, the Fe-5 iron-based powder comprises, by mass percentage: 0.45% C powder, 15% Cr powder, 0.6% Si powder, 0.3% Mn powder, and the balance being Fe powder; Step 2: Set the laser power to 350W, scanning speed to 8mm / s, powder trough width to 6mm, powder feeding rate to 0.20 rpm, track spacing to 0.35mm, single layer height to 0.3mm, and single track width to 0.7mm, and perform laser melting additive manufacturing on the clutch drive shaft platform with no machining allowance. Step 3: After laser cladding is completed, place the clutch drive shaft in an electric oven at 150℃ and keep it warm for 2 hours. Then turn off the oven power and let it cool with the oven. The clutch drive shaft platform repair is now complete.

[0026] Example 4 An additive repair method for a clutch drive shaft platform based on laser cladding technology includes the following steps: Step 1: Heat the clutch drive shaft to 150℃ in the furnace and hold for 30 minutes; place Fe-5 iron-based powder in a powder feeding jar and heat it to 150℃ in the jar, and hold for 30 minutes; wherein, the Fe-5 iron-based powder comprises, by mass percentage: 0.45% C powder, 15% Cr powder, 0.6% Si powder, 0.3% Mn powder, and the balance being Fe powder; Step 2: Set the laser power to 350W, scanning speed to 8mm / s, powder trough width to 6mm, powder feeding rate to 0.30 rpm, track spacing to 0.35mm, single layer height to 0.3mm, and single track width to 0.7mm. Perform laser melting additive manufacturing on the wear area of ​​the clutch drive shaft platform with no machining allowance. Step 3: After laser cladding is completed, place the clutch drive shaft in an electric oven at 150℃ and keep it warm for 2 hours. Then turn off the oven power and let it cool with the oven. The clutch drive shaft platform repair is now complete.

[0027] In Example 2, the laser cladding parameters had relatively low power, resulting in insufficient powder melting and localized areas where the powder was not completely melted. This led to a noticeably rougher surface after cladding, with high porosity and low bonding strength. In Examples 3 and 4, the increased laser cladding power largely eliminated the localized areas of unmelted powder, but the localized thickness after cladding was insufficient, preventing the edges from being polished during supplementary processing. In Example 1, to increase the cladding layer thickness, the powder feeding speed was increased, the scanning speed was reduced, and the power was appropriately increased to ensure complete powder melting.

[0028] Hardness tests were performed on the method of Example 1 using cladding test pieces. The cladding test pieces were grooved in the center (0.2 mm deep, 5 mm wide), stacked in single layers, and then pressed... Figure 3 The sample was fabricated as shown, and no cracks were observed during X-ray inspection. The laser cladding method was the same as in Example 1. Two samples were randomly selected for microhardness testing. The test data showed that the microhardness of the matrix material was 340.667 HV1 and 359.667 HV1 (corresponding to Rockwell hardness of approximately 37 HRC and 39 HRC), and the microhardness of the heat-affected zone was 300 HV1 and 301 HV1 (corresponding to Rockwell hardness of approximately 31.5 HRC), which were 11.9% and 16.3% lower than that of the matrix, respectively. The microhardness of the additive region was 815 HV1 and 829 HV1, corresponding to Rockwell hardness of approximately 65 HRC, which meets the technical requirement of surface hardness ≥ HRC61 or HV721 specified for the clutch drive shaft. Specific test data are shown in Table 1.

[0029] surface Microhardness test results (HV1) of 12Cr2Ni4A (Fe-5) process specimens. according to Figure 3The prepared mechanical property test specimens were 2.5 mm thick, with a groove in the middle, 0.5 mm deep and 5 mm wide. The tensile strength was taken as the average of the tensile strengths of three specimens under the same test conditions. Tensile tests were performed on the unwelded and welded specimens, and the test data are detailed in Table 2. The test data showed that the tensile strength of the original unwelded specimen was 1004.3 MPa, and the tensile strength after welding was 909.3 MPa.

[0030] Table 2 Strength test results of 12Cr2Ni4A (Fe-5) process specimens Metallographic examination was performed on the prepared test pieces, such as... Figures 4-6 As shown in the metallographic micrograph, no defects such as pores, inclusions, or cracks were found on the sample, indicating that the sample clad with Fe-5 powder meets the process requirements.

[0031] The clutch drive shaft platform is used to transmit the engine's input speed and power. During operation, this surface is primarily subjected to pressure. A metallographic microhardness test was conducted using a gradually increasing load method to perform a pressure failure test. Measurements of the indentation diameters for the 5kg, 10kg, 20kg, and 60kg pressure failure tests are shown in [reference needed]. Figures 7-10 A magnified view of the indentation diameter measurement from the 60kg pressure failure test is shown below. Figures 11-12 As shown, no microcracks were observed in the center and rounded corners of the 60kg specimen when examined under a 1000X microscope. This indicates that the specimen's resistance to compressive stress meets the standards.

[0032] By calculating the pressure on the clutch drive shaft platform and comparing it with the pressure test results of Fe-5 test pieces, it is determined whether the samples prepared by the process method of this invention meet the actual pressure requirements. Based on the relationship between parameters such as power and speed, the load transmitted by the clutch drive shaft platform is calculated, and the pressure on each platform is calculated. The engine is assumed to have a maximum emergency power of 2400 hp, which is converted to a power of 1764 kW. The relevant calculation process is as follows: S1. Calculate the load acting on the clutch drive shaft of a single-engine unit. F : F = P / v in, P For single-engine power, P = W / t t represents time, W represents engine power, and the calculated power is 1764kW. The applied load... F The value is 24955.49471 N; v For the engine linear velocity, v = πDnThe calculated result is 70.68583575 m / s. n The engine speed is 15000 rpm / min. D The circumference of the contact point between the engine and the clutch drive shaft is 90mm, and π is 3.1415927. The clutch drive shaft comprises 16 platforms, and the load on each platform is... F 1= F / 16, the calculated result is 1559.718419N; S2. Calculate the pressure exerted by the clutch drive shaft platform. p 1: p 1= F 1 / S in, p 1 represents the pressure exerted by a single engine on the clutch drive shaft, calculated to be 530.4 MPa. S This refers to the contact area between the engine and the clutch drive shaft. S = l × b , l This refers to the contact length between the engine and the clutch drive shaft. b The contact width between the engine and the clutch drive shaft, where , R This represents the equivalent radius of curvature, i.e., the roller radius, with a value of 0.00625m. l This indicates the effective length of the roller, with a value of 0.0195m. E * This represents the combined elastic modulus of the cylindrical roller in contact with the clutch platform, where, , E 1. E 2 represents the elastic modulus of the roller and clutch drive shaft platform, respectively. v 1. v 2 represents the Poisson's ratio of the roller and the clutch drive shaft, respectively. The elastic modulus of 12Cr2Ni4A is 190GPa~210GPa, and we take 200GPa. The elastic modulus of GCr15A is 206GPa~212GPa, and we take 209GPa. The Poisson's ratio of 12Cr2Ni4A is 0.28~0.30, and we take 0.29. The Poisson's ratio of GCr15A is 0.30~0.31, and we take 0.30.

[0033] Calculation results show that the pressure borne by the Fe-5 specimen under a 60kg load is approximately 8065.8MPa, and the pressure of the pressure failure test is approximately 15.21 times the maximum pressure when a single platform is working. The pressure failure test results show that the surface strength of the additive manufacturing using Fe-5 iron-based alloy powder laser cladding meets the requirements for use.

[0034] Table 3 Pressure of Fe5 specimens in destructive testing Wear resistance verification tests were conducted on laser-clad and unclad substrate samples using a fretting wear testing machine. The test design used a cylindrical roller as the upper sample and a square sample block as the lower sample. The contact stress between the wear pairs was controlled by adjusting the loading pressure and the effective length of the cylindrical roller to maintain consistency with the working pressure of the clutch drive shaft platform. The fretting frequency was set to 20Hz, the displacement amplitude to 200μm, and the number of fretting cycles to 5×10⁻⁶. 4 Next, a micro-motion abrasion resistance test was conducted under ambient temperature and atmospheric conditions. An optical 3D surface profilometer (SuperView W1-Pro) was used to measure the three-dimensional morphology of the wear tracks, obtaining data on the three-dimensional contour, wear depth, and wear volume. Comparison of the wear results revealed that the wear depth and wear amount of the clad sample were slightly smaller than those of the substrate sample, indicating that the abrasion resistance after cladding additive manufacturing was essentially the same as or even improved compared to the original substrate, meeting the usage standards.

[0035] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0036] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for additive repair of a clutch drive shaft platform based on laser cladding technology, characterized in that, Includes the following steps: Step 1: Preheat the clutch drive shaft and Fe-5 iron-based powder before welding; Step 2: Using Fe-5 iron-based powder, laser melting additive manufacturing is performed on the worn area of ​​the clutch drive shaft where there is no machining allowance; Step 3: After laser melting additive manufacturing, the clutch drive shaft is subjected to slow cooling after welding and additional processing. The repair of the clutch drive shaft is now complete. In step one, the specific method for preheating the clutch drive shaft before welding includes: heating the clutch drive shaft in the furnace to 100℃~150℃ and holding it at that temperature for 30 minutes. The specific method for preheating Fe-5 iron-based powder before welding includes: placing Fe-5 iron-based powder in a powder feeding tank, heating it to 100℃~150℃ with the tank, and holding it at that temperature for 30 minutes. In step two, the Fe-5 iron-based powder comprises, by mass percentage: 0.40-0.45% C powder, 13-15% Cr powder, 0.3-0.6% Si powder, 0.15-0.30% Mn powder, and the balance being Fe powder. In step two, when performing laser melting additive manufacturing on the worn area of ​​the clutch drive shaft with no machining allowance, the laser power is set to 300~400W, the scanning speed to 6~8mm / s, the powder trough width to 6mm, the powder feeding rate to 0.20~0.40 rpm, the track spacing to 0.35~0.5mm, the single layer height to 0.4mm, and the single track width to 0.7~1mm. In step three, after the clutch drive shaft repair is completed, it also includes performing a pressure calculation on the unrepaired clutch drive shaft and the repaired clutch drive shaft to determine whether the surface strength of the additive location of the repaired clutch drive shaft meets the usage requirements. The specific methods for performing pressure calculations on the unrepaired clutch drive shaft include: S1. Calculate the load acting on the clutch drive shaft of a single-engine unit. F : F = P / v in, P For single-engine power, P = W / t , t For time, W To do work for the engine; v For the engine linear velocity, v = πDn , n Engine speed, D This is the circumference of the contact point between the engine and the clutch drive shaft; The clutch drive shaft comprises 16 platforms, and the load on each platform is... F 1= F / 16; S2. Calculate the pressure applied to the clutch drive shaft. p 1: p 1= F 1 / S in, p 1 represents the pressure exerted by a single engine on the clutch drive shaft. S S = (This is the contact area between the engine and the clutch drive shaft.) l × b , l This refers to the contact length between the engine and the clutch drive shaft. b The contact width between the engine and the clutch drive shaft, where , R This represents the equivalent radius of curvature, i.e., the roller radius. l Indicates the effective length of the roller. E * This represents the combined elastic modulus of the cylindrical roller in contact with the clutch platform, where, , E 1. E 2 represents the elastic modulus of the roller and clutch drive shaft platform, respectively. v 1. v 2 represents the Poisson's ratio of the roller and the clutch drive shaft, respectively; The specific method for performing pressure calculations on the repaired clutch drive shaft includes: setting a test load. F 2. Apply load to the repaired cladding layer, based on the area of ​​the crater. S 2. Calculation F 2. Pressure failure test pressure under test load p 2, that is p 2= F 2 / S 2; like p 2≥ p 1. The surface strength of the additive location on the repaired clutch drive shaft meets the usage requirements; In step two, the hardness of the Fe-5 iron-based powder is 62HRC~67HRC; In step two, when laser melting additive manufacturing is performed on the worn area of ​​the clutch drive shaft, the effective additive depth is no more than 0.15 mm, and the thickness of a single laser cladding layer is 0.3~0.5 mm. In step three, the specific method for slow cooling of the worn area of ​​the clutch drive shaft after welding includes: after welding, placing the clutch drive shaft in an electric oven at a temperature of 130℃~150℃, keeping it warm for 2 hours, turning off the oven power, and cooling it with the oven.

2. The additive repair method for the clutch drive shaft platform based on laser cladding technology as described in claim 1, characterized in that, In step three, after the laser-melted additive manufacturing process involves slow cooling of the clutch drive shaft after welding, machining and shaping are also performed.

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