Clutch retainer precise additive repair method based on laser cladding technology

Abstract

The invention discloses a precise additive repairing method for a clutch retainer based on a laser cladding technology. The precise additive repairing method comprises the steps that the clutch retainer and 30CrMnSiA powder are preheated before welding; a laser cladding technology is adopted to carry out laser cladding on the worn part of the clutch retainer, and symmetric cladding is adopted in the circumferential direction to repair the wear; after laser cladding is completed, the clutch retainer is subjected to postwelding slow cooling; and performing laser shock peening and machining shaping on the surface of the clutch retainer subjected to additive repairing, and checking whether the surface is qualified or not to obtain the repaired clutch retainer. According to the method, remanufacturing additive repair of the clutch retainer is achieved, the additive process is optimized and improved, and workpiece deformation is further weakened by adopting symmetric cladding and uniform stress distribution in the circumferential direction. The workpiece deformation problem is solved from the two aspects of the additive method and the additive process, the surface hardness of the workpiece is recovered, and meanwhile the deformation problem caused by traditional heat treatment surface treatment is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of remanufacturing of aviation parts. More specifically, the present invention relates to a precise additive repair method for a clutch cage based on laser cladding technology. Background Technique

[0002] The clutch cage is installed on a certain type of main reducer clutch assembly. Its planar structure is as Figure 2 shown. The clutch cage is an important part of the clutch assembly of this type of reducer. Its main function is to position 16 clutch rollers through the pockets of the cage, and under the action of the shift lever and spring, push the clutch rollers towards the high position of the clutch driving shaft platform. During service, due to vibration and friction, the ФГ surface (the position mating with the clutch driving shaft) of the clutch cage is locally worn, resulting in out-of-tolerance mating dimensions and the performance of the part not meeting the technical requirements, affecting the normal operation of the main reducer. It is difficult to purchase Russian-made equipment aviation materials, so independent maintenance support is very crucial and urgent. Against this background, an additive repair process method for the clutch cage based on laser cladding technology emerged. Summary of the Invention

[0003] In order to achieve these and other advantages according to the present invention, there is provided a precise additive repair method for a clutch cage based on laser cladding technology, including the following steps: Step 1: Preheat the worn part of the clutch cage and the 30CrMnSiA powder before welding; Step 2: Use the 30CrMnSiA powder and adopt laser cladding technology to perform laser cladding on the worn part of the clutch cage, and carry out symmetric cladding in the circumferential direction to repair the wear; Step 3: After the laser cladding is completed, perform slow cooling after welding on the clutch cage; Step 4: Perform laser shock peening on the surface of the clutch cage after additive repair, machine and shape it, and after inspecting whether it is qualified, obtain the repaired clutch cage.

[0004] Preferably, in Step 1, the specific method for preheating the clutch cage before welding includes: heating the clutch cage in the furnace to 100°C - 150°C and holding for 20 - 40 minutes.

[0005] Preferably, in Step 1, the specific method for preheating the 30CrMnSiA powder before welding includes: placing the 30CrMnSiA powder in the powder feeding tank and heating the tank to 100°C - 150°C and holding for 20 - 40 minutes.

[0006] Preferably, in the first step, the 30CrMnSiA powder comprises: by mass percentage, 0.28% - 0.35% C powder, 0.80% - 1.10% Mn powder, 0.90% - 1.20% Si powder, 0.80% - 1.10% Cr powder, 0 - 0.4% Ni powder, and the balance Fe powder.

[0007] Preferably, in the second step, the specific method of laser cladding on the worn part of the clutch cage by laser cladding technology includes: using 30CrMnSiA powder, and performing melting repair on the worn part of the clutch cage when the laser power is 300 - 500 W, the scanning speed is 6 - 12 mm / s, and the powder feeding rate is 2 - 4 g / min.

[0008] Preferably, in the third step, the specific method of slow cooling after welding includes: after welding, placing the clutch cage in an electric oven at a temperature of 200°C - 220°C, keeping it warm for 2 h, turning off the power of the electric oven, and cooling it in the furnace.

[0009] Preferably, in the fourth step, the specific method of laser shock peening on the surface after additive repair of the clutch cage includes: setting the laser power to 6 J, the spot diameter to 2.2 mm, performing laser shock peening on the surface after additive repair, and the number of shock times is 1 time.

[0010] Preferably, in order to test the bonding strength between the cladding layer obtained by precision additive repair of the clutch cage based on laser cladding technology and the clutch cage, specimens are prepared and welded and cladded on the surface of the specimens according to the methods of the first step to the fourth step. Tensile tests are carried out on the specimens after welding and cladding, the tensile strength of the welded and cladded specimens is measured, and the fracture position is observed.

[0011] Preferably, the specimen is in a dumbbell-shaped sheet structure, with a thickness of 2.5 mm, prepared by wire cutting, and the burrs are removed with sandpaper. The specimen is grooved in the middle, with a depth of 1.25 mm and a width of 5 mm.

[0012] Preferably, in order to make the hardness of the body and the cladding layer of the specimen after welding and cladding reach the technical index requirement of HRC≥48.5, quenching + low-temperature tempering is also carried out on the specimen after welding and cladding. The specific method of quenching + low-temperature tempering includes: heating the specimen after welding and cladding to 890°C ± 10°C, keeping it warm for 30 min, quenching in oil at 10 - 70°C, heating to 230°C ± 10°C, keeping it warm for 30 min, and tempering in oil at 10 - 70°C.

[0013] The present invention has at least the following beneficial effects: 1. The present invention proposes an additive repair process based on laser cladding technology, realizing remanufacturing additive repair, improving the independent support ability of a certain type of main reducer clutch cage, and breaking the dilemma of unable to purchase spare parts.

[0014] 2. The present invention proposes a wear defect marking method based on three - coordinate inspection, realizing precise additive manufacturing, solving the deformation problem caused by a large amount of additive manufacturing, and at the same time optimizing and improving the additive manufacturing process. By adopting symmetric cladding in the circumferential direction and uniform stress distribution, the deformation of the workpiece is further weakened. Solving the workpiece deformation problem from two aspects of the additive manufacturing method and the additive manufacturing process has practical reference significance for subsequent research.

[0015] 3. The present invention proposes a symmetric laser shock peening technology for the additive part, restoring the surface hardness of the workpiece and at the same time solving the deformation problem caused by traditional heat treatment surface treatment, which is worthy of reference for subsequent research.

[0016] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will also be understood by those skilled in the art through the research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the flow chart of the precise additive repair method of the clutch cage based on laser cladding technology provided by the present invention; Figure 2 is the structural schematic diagram of the clutch cage that needs to be repaired by laser cladding in the present invention; Figure 3 is the 200X metallographic micrograph of 30CrMnSiA laser cladding in Example 1; Figure 4 is the structural schematic diagram of the mechanical property test specimen made; Figure 5 is the physical drawing of the tensile test after cladding of the mechanical property test specimen. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The following further describes the present invention in detail with reference to the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0019] It should be understood that terms such as "having", "comprising" and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations. Example 1 As Figure 1 shown, this embodiment provides a precise additive repair method of a clutch cage based on laser cladding technology, including the following steps: Step 1: First, mark the additive parts by combining coordinate measuring machine (CMM) scanning and differential measurement; preheat the clutch cage and 30CrMnSiA powder before welding respectively. Heat the clutch cage in the furnace to 150°C and hold for 30 minutes; place the 30CrMnSiA powder in the powder feeder and heat it together with the feeder to 150°C and hold for 30 minutes. Among them, the 30CrMnSiA powder includes: by mass percentage, 0.35% C powder, 1.10% Mn powder, 1.20% Si powder, 1.10% Cr powder, 0.4% Ni powder and the balance Fe powder; Step 2: Use 30CrMnSiA powder and adopt laser cladding technology to perform laser cladding on the worn part of the clutch cage. Symmetric cladding is carried out in the circumferential direction to repair the wear. The laser power is 450W, the scanning speed is 8mm / s, and the powder feeding rate is 3g / min; Step 3: After laser cladding is completed, place the clutch cage in an electric oven at a temperature of 220°C, hold for 2 hours, turn off the power of the electric oven, and cool it in the furnace; Step 4: Set the laser power to 6J, the spot diameter to 2.2mm, perform laser shock peening on the surface after additive repair, the number of shock times is 1 time. After machining, shaping and inspection for qualification, the repaired clutch cage is obtained.

[0020] Example 2 A precise additive repair method for a clutch cage based on laser cladding technology, comprising the following steps: Step 1: First, mark the additive parts by combining coordinate measuring machine (CMM) scanning and differential measurement; preheat the clutch cage and 30CrMnSiA powder before welding respectively. Heat the clutch cage in the furnace to 150°C and hold for 30 minutes; place the 30CrMnSiA powder in the powder feeder and heat it together with the feeder to 150°C and hold for 30 minutes. Among them, the 30CrMnSiA powder includes: by mass percentage, 0.35% C powder, 1.10% Mn powder, 1.20% Si powder, 1.10% Cr powder, 0.4% Ni powder and the balance Fe powder; Step 2: Use 30CrMnSiA powder and adopt laser cladding technology to perform laser cladding on the worn part of the clutch cage. Symmetric cladding is carried out in the circumferential direction to repair the wear. The laser power is 350W, the scanning speed is 6mm / s, and the powder feeding rate is 2g / min; Step 3: After laser cladding is completed, place the clutch cage in an electric oven at a temperature of 220°C, hold for 2 hours, turn off the power of the electric oven, and cool it in the furnace; Step 4: Set the laser power to 6 J, the spot diameter to 2.2 mm, perform laser shock peening on the surface after additive repair, with the number of shock times being 1 time. After machining, shaping and inspecting for qualification, the repaired clutch cage is obtained.

[0021] Example 3 A precise additive repair method for a clutch cage based on laser cladding technology, comprising the following steps: Step 1: First, mark the additive part by combining coordinate measuring machine scanning and differential measurement; preheat the clutch cage and 30CrMnSiA powder before welding respectively. Heat the clutch cage in the furnace to 150 °C and keep it warm for 30 min; place the 30CrMnSiA powder in the powder feeding tank and heat it in the tank to 150 °C and keep it warm for 30 min; wherein, the 30CrMnSiA powder comprises: by mass percentage, 0.35% C powder, 1.10% Mn powder, 1.20% Si powder, 1.10% Cr powder, 0.4% Ni powder and the balance Fe powder; Step 2: Use 30CrMnSiA powder and adopt laser cladding technology to perform laser cladding on the worn part of the clutch cage, and perform symmetric cladding in the circumferential direction to repair the wear. The laser power is 500 W, the scanning speed is 10 mm / s, and the powder feeding rate is 4 g / min; Step 3: After laser cladding is completed, place the clutch cage in an electric oven at a temperature of 220 °C, keep it warm for 2 h, turn off the power of the electric oven, and cool it with the furnace; Step 4: Set the laser power to 6 J, the spot diameter to 2.2 mm, perform laser shock peening on the surface after additive repair, with the number of shock times being 1 time. After machining, shaping and inspecting for qualification, the repaired clutch cage is obtained.

[0022] Repair the clutch cage according to the repair methods of Examples 1 - 3. The overlap rate at the cladding part in Example 1 is 45%, the hardness of the weld layer is 46.9 HRC, and the tensile strength is 642 MPa; the overlap rate at the cladding part in Example 2 is 35%, the hardness of the weld layer is 46.1 HRC, and the tensile strength is 598 MPa; the overlap rate at the cladding part in Example 3 is 50%, the hardness of the weld layer is 47.3 HRC, and the tensile strength is 651 MPa.

[0023] According to the performance test results of Embodiment 1 - Embodiment 3, and based on the particularity of the repair of this type of clutch cage (only local additive manufacturing is required, and the welding layer is relatively thin. Therefore, when the laser power reaches the state of melting the powder, the smaller the powder feeding rate, the less heat transfer is generated, and the smaller the thermal deformation. Considering the results of Embodiment 1 - Embodiment 3 comprehensively, when the power is 350W, the powder melting is not sufficient, and its bonding force is weak, resulting in a lower tensile strength. The performance test results of 450W and 500W are not much different, but the powder feeding rate in Embodiment 1 is low, and the generated heat is small. Considering from the perspective of small deformation, the laser cladding parameters of Embodiment 1 are the optimal laser cladding parameters.

[0024] Manufacture mechanical property test specimens as shown in Figure 4 with a thickness of 2.5mm. All specimens are prepared by wire cutting and the burrs are removed with sandpaper. The cladding specimens are grooved in the middle with a depth of 1.25mm and a width of 5mm. The tensile strength is the average value of the tensile strengths of 2 to 3 specimens under the same test conditions.

[0025] Treat the specimens using the additive repair method of Embodiment 1, that is, perform additive repair on the prepared specimens according to the precise additive repair method of the clutch cage based on laser cladding technology in Embodiment 1. Test the hardness of the annealed specimens and those after quenching + low-temperature tempering respectively. The heat treatment system is: heat to 890°C ± 10°C, hold for 30min, quench in oil at 10 - 70°C, heat to 230°C ± 10°C, hold for 30min, and temper in oil at 10 - 70°C to obtain Table 1 and Table 2: Table 1 Hardness of the annealed process specimens (HV 0.5 ) Table 2 Hardness test of the specimens with the quenching + low-temperature tempering process (HV 0.5 ) The data shows that the specimens after quenching + low-temperature tempering have reached the hardness index of the clutch cage.

[0026] Conduct metallographic inspection on the specimens made by laser cladding. The metallographic diagram is as shown in Figure 3 No defects such as pores, inclusions, and cracks are found, meeting the technical requirements.

[0027] After heat treatment, tensile specimens were made. The test data are shown in Table 3. Tensile tests were conducted on unwelded and welded specimens. The welded specimens were simulated for welding repair according to the precise additive repair method for clutch retainer based on laser cladding technology in Example 1. The test data are shown in Table 3. The tensile strength of the welded specimens is basically consistent with that of the parent material, and the fracture positions are all in the parent material, indicating that the strength of the welded part is close to or reaches the strength of the parent material. (Heat treatment system: heating to 890℃±10℃, keeping warm for 30min, quenching in oil at 10~70℃; heating to 230℃±10℃, keeping warm for 30min, tempering in oil at 10~70℃) Table 3 Strength test results of 30CrMnSiA process test pieces like Figure 5 As shown in the figure, the fracture of the tensile test piece is random, some are close to the joint position, and some are in the middle of the sample. The fracture position of the welding test piece is not at the welding position, which means that the ductility of the welding area is consistent with that of the matrix, and the tensile process can produce deformation along with the matrix. Combined with the test data of the quenching + low temperature tempering state test piece, it is shown that the strength of the welded joint is close to or reaches the strength of the parent material.

[0028] After the bonding strength test, the process parts were used for process verification. Before cladding, the roundness and concentricity of the clutch retainer surface A, surface B, and surface C (surface to be repaired) and the flatness of the end surface T were checked by three-coordinate scanning. The inspection results are shown in Table 4. The inspection results of the geometric tolerances of each surface after cladding are shown in Table 5. It was found that the inspection data of each part basically did not change, indicating that the laser cladding precision additive method proposed by the present invention basically did not produce deformation.

[0029] Table 4 Check of shape and position tolerance before cladding Table 5: Check of geometric tolerance after cladding After heat treatment, the shape and position tolerances of each surface were checked. From the data analysis in Table 6, the data of each part changed greatly, especially the roundness of surface A increased from about 0.067mm before heat treatment to 0.15mm. The shape and position tolerances of other parts also changed to varying degrees. Analysis showed that the large shape and position tolerances were caused by the internal stress generated by the heat difference during the second heat treatment.

[0030] Table 6 Geometric tolerance inspection after heat treatment Considering that the clutch cage has a relatively complex squirrel-cage structure and the actual situation of severe deformation during the re-heat treatment of the process parts, based on this problem, the present invention uses the method of laser shock peening to increase the surface hardness, and the laser shock peening only strengthens the cladding part, and other parts are not affected. The hardness test of the test piece was carried out by laser shock peening (6J laser shock, spot diameter 2.2mm, shock 1 time), and the results are shown in Table 7. The hardness meets the technical index requirements.

[0031] Table 7 Hardness Test of Laser Shock Peening for Process Test Pieces After the shock strengthening, it was found that there was a slight deformation on the strengthened surface. Combining with the technical characteristics of the shock strengthening, it was analyzed that the slight deformation was mainly caused by the irregularity of the cladding layer and the difference in the distribution of surface tensile and compressive stresses after laser shock peening. Aiming at the problem of uneven distribution of surface tensile and compressive stresses, the present invention adopts the method of symmetric cladding and symmetric laser shock peening to make the distribution of surface tensile and compressive stresses balanced, and the deformation problem is solved.

[0032] The equipment quantities and processing scales described here are used to simplify the description of the present invention. The applications, modifications, and variations of the present invention are obvious to those skilled in the art.

[0033] Although the embodiments of the present invention have been disclosed above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional 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 the illustrated examples described here.

Claims

1. A precise additive repair method for a clutch cage based on laser cladding technology, characterized in that It includes the following steps: Step 1: Preheat the clutch cage and 30CrMnSiA powder before welding; Step 2: Use 30CrMnSiA powder and adopt laser cladding technology to perform laser cladding on the worn part of the clutch cage, and perform symmetric cladding in the circumferential direction to repair the wear; Step 3: After the laser cladding is completed, perform slow cooling of the clutch cage after welding; Step 4: Perform laser shock peening on the surface of the clutch cage after additive repair, perform machining and shaping, and check whether it is qualified to obtain the repaired clutch cage.

2. The precise additive repair method for the clutch cage based on the laser cladding technology according to claim 1, characterized in that In the above Step 1, the specific method for preheating the clutch cage before welding includes: heating the clutch cage in the furnace to 100°C - 150°C and holding for 20 - 40 minutes.

3. The precise additive repair method for the clutch cage based on the laser cladding technology according to claim 1, wherein In the above Step 1, the specific method for preheating the 30CrMnSiA powder before welding includes: placing the 30CrMnSiA powder in the powder feeding tank and heating it in the tank to 100°C - 150°C and holding for 20 - 40 minutes.

4. The precise additive repair method for the clutch cage based on the laser cladding technology according to claim 1, wherein In the above Step 1, the 30CrMnSiA powder includes: by mass percentage, 0.28% - 0.35% C powder, 0.80% - 1.10% Mn powder, 0.90% - 1.20% Si powder, 0.80% - 1.10% Cr powder, 0 - 0.4% Ni powder and the balance Fe powder.

5. The precise additive repair method for the clutch cage based on the laser cladding technology according to claim 1, wherein In the above Step 2, the specific method for performing laser cladding on the worn part of the clutch cage by using laser cladding technology includes: using 30CrMnSiA powder to perform melting repair on the worn part of the clutch cage when the laser power is 300 - 500W, the scanning speed is 6 - 12mm / s, and the powder feeding rate is 2 - 4g / min.

6. The precise additive repair method for the clutch cage based on the laser cladding technology according to claim 1, characterized in that, In the above Step 3, the specific method for slow cooling after welding includes: after welding, place the clutch cage in an electric oven at a temperature of 200°C - 220°C, hold for 2 hours, turn off the power of the electric oven, and cool with the furnace.

7. The precise additive repair method for the clutch cage based on the laser cladding technology according to claim 1, characterized in that In the above Step 4, the specific method for performing laser shock peening on the surface of the clutch cage after additive repair includes: set the laser power to 6J, the spot diameter to 2.2mm, perform laser shock peening on the surface after additive repair, and the number of shock times is 1 time.

8. The precise additive repair method for the clutch cage based on the laser cladding technology according to claim 1, characterized in that, In order to test the bonding strength between the cladding layer obtained by the precise additive repair method of the clutch cage based on laser cladding technology and the clutch cage, prepare test pieces and perform welding cladding on the surface of the test pieces according to the methods of Step 1 to Step 4, perform a tensile test on the welded and clad test pieces, measure the tensile strength of the clad welding test pieces, and observe the fracture position.

9. The precise additive repair method for the clutch cage based on the laser cladding technology according to claim 8, characterized in that, The test piece has a dumbbell-shaped sheet structure, with a thickness of 2.5mm, is prepared by wire cutting, and the burrs are removed with sandpaper. The test piece is grooved in the middle, with a depth of 1.25mm and a width of 5mm.

10. The precise additive repair method for the clutch cage based on the laser cladding technology according to claim 8, characterized in that, In order to meet the technical index requirements that the hardness of the substrate and the cladding layer of the test piece after welding cladding reaches HRC ≥ 48.5, it also includes quenching + low-temperature tempering of the test piece after welding cladding. The specific method of performing quenching + low-temperature tempering includes: heating the test piece of welding cladding to 890°C ± 10°C, holding for 30 min, quenching in oil at 10 - 70°C, heating to 230°C ± 10°C, holding for 30 min, and tempering in oil at 10 - 70°C.

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