Machining process of bearing outer ring

Abstract

The application relates to the field of bearing machining, and particularly discloses a machining process for a bearing outer ring, which comprises the following steps: S1. pretreatment; S2. surface nanocrystallization treatment; S3. rough grinding; S4. fine grinding; S5. superfinishing; and S6. cleaning. The surface nanocrystallization treatment is added before grinding, the raceway surface layer is subjected to severe plastic deformation through high-speed projectile impact, a gradient nanocrystalline structure layer which is gradually changed from the surface nanocrystalline to the coarse grain in the center is formed, the structure layer can improve the surface hardness and strength, reduce the subsequent grinding force and grinding heat, inhibit thermal damage and organizational phase change, deep stable residual compressive stress is introduced into the surface layer, the tensile stress generated during grinding is offset, the raceway is finally in a beneficial compressive stress state, and therefore, a high-hardness and low-damage high-quality surface layer is obtained, and the bearing matching precision, running stability and service reliability are improved.

Description

Technical Field

[0001] This application relates to the field of bearing processing, and more specifically, it relates to a processing technology for the outer ring of a bearing. Background Technology

[0002] As a core component of mechanical transmission systems, bearings are widely used in automobiles, machine tools, construction machinery, aerospace and other fields. The outer ring of the bearing is the bearing track for the balls and the assembly reference for the cage. The dimensional accuracy of its raceway, surface quality, internal hole form and position tolerances and end face flatness directly affect the contact state between the balls and the outer ring, the fit clearance between the cage and the outer ring, and thus determine the bearing's friction characteristics, vibration noise, load-bearing capacity and fatigue life.

[0003] Currently, the machining process for bearing outer rings generally includes: forging blank preparation - turning forming - heat treatment (quenching + low temperature tempering) - grinding (rough grinding, fine grinding of raceways and end faces) - ultra-precision grinding. In this process, raceway grinding is mostly carried out using abrasive wheel grinding. The grinding heat generated during the grinding process can easily cause thermal damage and phase transformation of the raceway surface, and introduce residual tensile stress. This will reduce the surface hardness and wear resistance of the raceway, induce early wear, and directly affect the bearing's fitting accuracy, operational stability and service reliability, which needs to be improved. Summary of the Invention

[0004] In order to improve the machining process of bearing outer rings, the grinding heat generated during the grinding process can easily cause thermal damage and phase transformation of the raceway surface, and introduce residual tensile stress, thereby reducing the surface hardness and wear resistance of the raceway and inducing early wear. This application provides a machining process for bearing outer rings.

[0005] The technical solution for machining the outer ring of a bearing provided in this application is as follows:

[0006] A machining process for a bearing outer ring includes the following steps:

[0007] S1. Pretreatment: The outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted, and then the sandblasted outer ring is placed in a water-based cleaning solution at 60-75℃ and ultrasonically cleaned for 15-20 minutes, and then dried at 80-100℃ for 15-25 minutes.

[0008] S2. Surface nano-treatment: The pretreated bearing outer ring is fixed on a surface mechanical grinding equipment, with the bearing outer ring raceway surface facing the processing head. GCr15 steel balls with a diameter of 1-3mm are used as projectiles to impact the raceway surface at a speed of 40-50m / s. The feed speed of the processing head is 300-500mm / min, and the angle between the projectile impact direction and the normal of the raceway surface is 0°-45°. The treatment time is 10-30min.

[0009] S3. Rough grinding: The raceway is rough ground using a CBN grinding wheel with ceramic bond. The grit size of the CBN grinding wheel is 80 / 100-120 / 140, the grinding wheel linear speed is 60-80m / s, the workpiece rotation speed is 100-300rpm, and the radial feed rate is 0.01-0.02mm / stroke.

[0010] S4. Fine grinding: The raceway after rough grinding is finely ground using a CBN grinding wheel with resin bond. The grit size of the CBN grinding wheel is 170 / 200-230 / 270, the grinding wheel linear speed is 80-120m / s, the workpiece rotation speed is 200-500rpm, the radial feed is 0.002-0.005mm / stroke, and spark-free finishing is performed.

[0011] S5. Ultra-precision machining: Using silicon carbide oilstone with a particle size of W5-W10, the raceway surface of the finely ground bearing outer ring is subjected to ultra-precision machining for 2-5 minutes under a pressure of 0.1-0.3MPa and an oscillation frequency of 500-1000 times / min.

[0012] S6. Cleaning: Place the ultra-finely ground bearing outer ring in the first cleaning tank and ultrasonically clean it for 3-5 minutes in an alkaline cleaning solution at 50-60℃. Then transfer the bearing outer ring to the second cleaning tank and ultrasonically rinse it for 2-3 minutes in flowing deionized water at 50-60℃. Finally, transfer the bearing outer ring to the third cleaning tank and ultrasonically clean it for 1-2 minutes in deionized water at room temperature with 0.1-0.3wt% short-term rust inhibitor added. After cleaning, dry it at 60-80℃ for 20-30 minutes.

[0013] By adopting the above technical solution, a surface nano-treatment process is introduced before grinding. The raceway surface is repeatedly impacted by high-speed shot, which induces severe plastic deformation on the surface layer, thereby forming a gradient nanocrystalline structure layer with a gradient transition from surface nanocrystals to coarse grains in the core. The gradient nanocrystalline structure layer has extremely high hardness and strength, which enhances the material's resistance to grinding. This reduces the grinding force and grinding heat generated during subsequent rough and fine grinding, and inhibits the generation of thermal damage and phase transformation. On the other hand, the nano-treatment process pre-forms stable and deep residual compressive stress on the surface layer, which can offset the harmful tensile stress generated by subsequent grinding. This makes the final raceway surface layer stable in a beneficial compressive stress state or an extremely low tensile stress level, resulting in a high-hardness and low-damage high-quality working surface layer, which improves the bearing's fitting accuracy, operational stability and service reliability.

[0014] Preferably, the water-based cleaning solution comprises the following components: 3-5 wt% amphoteric surfactant, 1-2 wt% glycerol, 0.5-1.5 wt% urea, and the balance being deionized water.

[0015] By adopting the above technical solution, urea can undergo hydrolysis and generate active nitrogen species under the combined action of ultrasound and heating. At the same time, glycerol may decompose in the hot spot of local high temperature and high pressure generated by ultrasonic cavitation, providing active carbon species. Under the stirring and impact provided by the ultrasonic cavitation effect, these active nitrogen and active carbon can be adsorbed and slightly penetrated into the highly active roller surface after sandblasting. In the subsequent surface nano-sizing treatment, these penetrated nitrogen and carbon atoms, as interstitial atoms, can become dislocation pinning centers, promoting dislocation entanglement and recombination, thereby driving grain refinement more efficiently. This helps to obtain a gradient nanocrystalline structure layer with finer and more uniform grains under the same process parameters.

[0016] Preferably, in step S1, the sandblasted bearing outer ring is immersed in a water-based cleaning solution and ultrasonically cleaned at room temperature for 3-5 minutes. Then, the cleaning solution is heated to 60-75°C at a rate of 1-2°C / min and ultrasonically cleaned at a constant temperature for 15-20 minutes. Next, the bearing outer ring is transferred to another tank of deionized water at room temperature and ultrasonically cleaned for 2-3 minutes. Finally, the bearing outer ring is transferred to a drying oven filled with nitrogen and dried at 80-100°C for 15-25 minutes.

[0017] By adopting the above technical solution, the cavitation effect of ultrasound and the wetting effect of surfactant are used to remove the abrasive dust and most of the loose contaminants remaining after sandblasting, providing a clean base for subsequent chemical reactions and avoiding the contaminants from being sintered on the metal surface at high temperatures.

[0018] By raising the temperature, the cleaning fluid and the workpiece can reach the target temperature evenly and synchronously, avoiding thermal shock and uneven surface reaction caused by direct immersion in hot liquid or rapid heating.

[0019] In the isothermal range, continuous ultrasound provides the thermal energy to sustain the reaction and ensures the uniform distribution and renewal of active reactive substances (such as urea decomposition products) on the workpiece surface through cavitation stirring.

[0020] After constant temperature activation, the workpiece is transferred to room temperature deionized water for ultrasonic rinsing, which can instantly terminate the chemical reaction on the surface and prevent excessive reaction. At the same time, the temperature difference and ultrasound work together to wash away unreacted substances and by-products on the surface, obtaining a pure activated surface and preventing stains from forming after drying.

[0021] The final drying is carried out under nitrogen protection to isolate oxygen and ensure that the fresh metal surface with high chemical activity obtained from the above process is not oxidized during the drying process. This allows the workpiece to be transferred to the next surface nano-treatment process in the best state of high activity and no oxidation.

[0022] Preferably, the amphoteric surfactant is a mixture of cocamidopropyl betaine and disodium lauroyl amphoteric diacetate in a mass ratio of 3:2.

[0023] By adopting the above technical solution, cocamidopropyl betaine provides excellent wetting, penetration and emulsifying degreasing capabilities, which can quickly break down and remove grease and organic contaminants from the workpiece surface. Disodium lauroamphodiacetate has extremely strong dispersing and suspending capabilities, which can prevent secondary deposition of solid particles such as abrasive dust and metal shavings peeled off from the workpiece surface. The combination of the two achieves efficient and simultaneous removal and stable suspension of complex dirt (oil stains and solid particles), ensuring that an ultra-clean surface without visible particle residue can be obtained in the room temperature cleaning stage, laying a cleaner physical foundation for subsequent chemical activation.

[0024] Preferably, in step S1, the outer ring of the bearing, after being quenched and tempered at low temperature, is placed in liquid nitrogen at -196°C for 1-3 hours, then allowed to return to room temperature in air before being sandblasted cleaned.

[0025] By adopting the above technical solution, cryogenic treatment drives the transformation of retained austenite to martensite and promotes the precipitation of dispersed fine carbides in the matrix, thereby improving the overall hardness, dimensional stability, and matrix strength of the material. This treatment also introduces crystal defects such as high-density dislocations and twins, so that during the subsequent sandblasting process, the impact energy can be more concentrated on driving the proliferation and interaction of pre-existing defects on the surface, forming a pre-activated layer of high-density dislocations, rather than being largely absorbed by the plastic deformation of the matrix. Thus, under the same surface nano-sizing process parameters, it can more efficiently promote dislocation entanglement and grain boundary reorganization, obtaining a gradient nanocrystalline reinforced layer with finer grains, greater thickness, and more uniform structure. While maintaining high dimensional stability, it improves the contact fatigue strength and wear resistance of the raceway surface, thereby extending the service life of the bearing.

[0026] Preferably, in step S1, the sandblasting cleaning step is as follows: using cast steel shot with a diameter of 0.3-0.6 mm, sandblasting the raceway area of ​​the bearing outer ring after quenching and low-temperature tempering heat treatment for 2-5 minutes under a pressure of 0.5-0.7 MPa; then using white corundum of 80-120 mesh, sandblasting the non-raceway area of ​​the bearing outer ring after quenching and low-temperature tempering heat treatment for 2-5 minutes under a pressure of 0.3-0.4 MPa.

[0027] By adopting the above technical solutions, using relatively soft but plastically formable cast steel shot, combined with high pressure, to sandblast the raceway area can effectively clean the surface and introduce beneficial plastic deformation and residual compressive stress into the raceway surface layer. This reduces the deformation resistance during the nano-sizing process and promotes the formation of a thicker and more uniform nanocrystalline layer, thereby improving the fatigue resistance and wear resistance of the raceway. Using high-hardness white corundum, combined with lower pressure, to sandblast the non-raceway area can efficiently remove oxide scale and contaminants, while avoiding the introduction of excessive residual stress or surface roughening. This ensures the dimensional stability of the non-raceway area and prevents deformation or stress concentration caused by improper sandblasting.

[0028] Preferably, the alkaline cleaning solution comprises the following components: 1-2.5 wt% silicate, 0.5-1.5 wt% nonionic surfactant and 0.05-0.1 wt% benzotriazole, with the balance being water.

[0029] By adopting the above technical solutions, silicates can provide a suitable alkaline environment and corrosion inhibition, effectively removing oil stains, grinding debris, and machining residues while avoiding corrosion and pitting on the bearing outer ring surface. Nonionic surfactants have excellent wetting, penetration, and decontamination capabilities, and can quickly remove oil stains and impurities adhering to the bearing outer ring surface, ensuring thorough cleaning. Benzotriazole, as a metal corrosion inhibitor, can form a dense protective film on the bearing outer ring surface, inhibiting oxidation and rust during cleaning and drying, and improving the surface cleanliness and appearance quality of the workpiece. This cleaning solution achieves efficient cleaning while also having good corrosion inhibition and rust prevention effects, providing a stable and clean surface condition for the subsequent assembly and service of the bearing.

[0030] Preferably, the nonionic surfactant is a fatty alcohol polyoxyethylene ether.

[0031] By adopting the above technical solution, fatty alcohol polyoxyethylene ether has good alkali resistance, emulsification and dispersibility and detergency. It can effectively remove grinding oil, metal shavings and processing residues from the outer ring surface of the bearing. At the same time, the foaming amount is moderate, it is easy to rinse and will not leave residues on the raceway surface, ensuring the cleanliness of the surface after cleaning. It does not corrode the steel material of the bearing outer ring and has good compatibility with silicates and benzotriazole, which synergistically improve the overall performance of the cleaning solution.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. Before grinding, a surface nano-treatment is added. The surface of the raceway undergoes severe plastic deformation due to the impact of high-speed shot, forming a gradient nanocrystalline structure layer that transitions from surface nanocrystals to coarse grains in the core. This structure layer can improve surface hardness and strength, reduce subsequent grinding force and grinding heat, inhibit thermal damage and phase transformation, and introduce deep stable residual compressive stress into the surface layer to offset the tensile stress generated by grinding. This ensures that the raceway is ultimately in a beneficial compressive stress state, thereby obtaining a high-hardness and low-damage high-quality surface layer, improving bearing fit accuracy, operational stability and service reliability.

[0034] 2. This application uses a water-based cleaning solution composed of urea, glycerol and amphoteric surfactant. Under the combined action of ultrasound and heating, urea hydrolyzes to produce active nitrogen species, and glycerol decomposes in the ultrasonic cavitation hot spot to produce active carbon species. The stirring and impacting action of ultrasonic cavitation causes the two active species to be adsorbed and slightly penetrate into the highly active roller surface after sandblasting. In the subsequent surface nano-sizing treatment, the penetrated nitrogen and carbon atoms act as interstitial atoms to form dislocation pinning centers, promoting dislocation entanglement and recombination, which can drive grain refinement more efficiently and obtain a finer and more uniform gradient nanocrystalline structure layer under the same process parameters.

[0035] 3. Through programmed control of room temperature ultrasonic cleaning, heating activation, rapid cooling rinsing termination, and inert atmosphere drying, the surface of the bearing outer ring is precisely activated. Detailed Implementation

[0036] The present application will be further described in detail below with reference to the embodiments.

[0037] Information Bearing outer ring Material: GCr15SiMn steel, quenched + low temperature tempered, hardness: HRC 60-65 CBN grinding wheel with vitrified bond CBN abrasive concentration: 150%, hardness grade: K grade, organization number: 8 CBN grinding wheel with resin bond CBN abrasive concentration: 100%, hardness grade: L grade Cast steel shot Hardness: HRC 45-50 White corundum Al203 content > 95% Silicate Sodium metasilicate Short-term rust inhibitor Ammonium octoate

[0038] It should be noted that wt% refers to weight percentage.

[0039] Unless otherwise specified, all raw materials used in the following embodiments are commercially available.

[0040] Example 1

[0041] This application discloses a machining process for the outer ring of a bearing, including the following steps:

[0042] S1. Pretreatment: The outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted. The sandblasting steps are as follows: using cast steel shot with a diameter of 0.3-0.6 mm, the raceway area of ​​the outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted for 5 min under a pressure of 0.5 MPa. Then, using white corundum of 80-120 mesh, the non-raceway area of ​​the outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted for 5 min under a pressure of 0.3 MPa. Afterwards, the sandblasted outer ring of the bearing is placed in a water-based cleaning solution at 60℃. The water-based cleaning solution is a deionized aqueous solution containing 5 wt% amphoteric surfactant, wherein the amphoteric surfactant is a mixture of cocamidopropyl betaine and disodium lauroyl amphoteric diacetate with a mass ratio of 3:2. The ultrasonic cleaning is performed at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm² for 20 min, and then dried at 80℃ for 25 min.

[0043] S2. Surface nano-treatment: The pretreated bearing outer ring is fixed on a surface mechanical grinding equipment, with the raceway surface of the bearing outer ring facing the processing head. GCr15 steel balls with a diameter of 1-3mm are used as projectiles to impact the raceway surface at a speed of 40m / s. The feed speed of the processing head is 300mm / min, and the angle between the impact direction of the projectiles and the normal of the raceway surface is 0°. The treatment lasts for 30min.

[0044] S3. Rough grinding: The raceway is rough ground using a CBN grinding wheel with ceramic bond. The grit size of the CBN grinding wheel is 80 / 100-120 / 140, the grinding wheel linear speed is 60m / s, the workpiece rotation speed is 100rpm, and the radial feed rate is 0.01mm / stroke.

[0045] S4. Fine grinding: The raceway after rough grinding is finely ground using a CBN grinding wheel with resin bond. The grit size of the CBN grinding wheel is 170 / 200-230 / 270, the grinding wheel linear speed is 80m / s, the workpiece rotation speed is 200rpm, the radial feed is 0.002mm / stroke, and spark-free finishing is performed.

[0046] S5. Ultra-precision machining: Using silicon carbide oilstone with a particle size of W5-W10, the raceway surface of the finely ground bearing outer ring is subjected to ultra-precision machining for 5 minutes under a pressure of 0.1MPa and an oscillation frequency of 500 times / min.

[0047] S6. Cleaning: Place the ultra-finely ground bearing outer ring in the first cleaning tank and ultrasonically clean it for 5 minutes at 40 kHz and 1.2 W / cm² power density in an alkaline cleaning solution at 50 ℃. The alkaline cleaning solution includes the following components: 1 wt% silicate, 0.5 wt% nonionic surfactant, and 0.05 wt% benzotriazole, with the balance being water. The nonionic surfactant is fatty alcohol polyoxyethylene ether. Then, transfer the bearing outer ring to the second cleaning tank and ultrasonically rinse it for 3 minutes at 40 kHz and 0.6 W / cm² power density in flowing deionized water at 50 ℃. Finally, transfer the bearing outer ring to the third cleaning tank and ultrasonically clean it for 2 minutes at 40 kHz and 0.6 W / cm² power density in deionized water with 0.1 wt% short-term rust inhibitor added at room temperature. After cleaning, dry it at 60 ℃ for 30 minutes.

[0048] Example 2

[0049] This application discloses a machining process for the outer ring of a bearing, including the following steps:

[0050] S1. Pretreatment: The outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted. The sandblasting steps are as follows: using cast steel shot with a diameter of 0.3-0.6 mm, the raceway area of ​​the outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted for 2 minutes under a pressure of 0.7 MPa. Then, using white corundum of 80-120 mesh, the non-raceway area of ​​the outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted for 2 minutes under a pressure of 0.4 MPa. Afterwards, the sandblasted outer ring of the bearing is placed in a water-based cleaning solution at 75℃. The water-based cleaning solution is a deionized aqueous solution containing 5 wt% amphoteric surfactant, wherein the amphoteric surfactant is a mixture of cocamidopropyl betaine and disodium lauroyl amphoteric diacetate with a mass ratio of 3:2. The ultrasonic cleaning is performed at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm² for 15 minutes, and then dried at 100℃ for 15 minutes.

[0051] S2. Surface nano-treatment: The pretreated bearing outer ring is fixed on a surface mechanical grinding equipment, with the bearing outer ring raceway surface facing the processing head. GCr15 steel balls with a diameter of 1-3mm are used as projectiles to impact the raceway surface at a speed of 50m / s. The feed speed of the processing head is 500mm / min, and the angle between the projectile impact direction and the normal of the raceway surface is 45°. The treatment lasts for 10min.

[0052] S3. Rough grinding: The raceway is rough ground using a CBN grinding wheel with ceramic bond. The grit size of the CBN grinding wheel is 80 / 100-120 / 140, the grinding wheel linear speed is 80m / s, the workpiece rotation speed is 300rpm, and the radial feed rate is 0.02mm / stroke.

[0053] S4. Fine grinding: The raceway after rough grinding is finely ground using a CBN grinding wheel with resin bond. The grit size of the CBN grinding wheel is 170 / 200-230 / 270, the grinding wheel linear speed is 120m / s, the workpiece rotation speed is 500rpm, the radial feed is 0.005mm / stroke, and spark-free finishing is performed.

[0054] S5. Ultra-precision machining: Using silicon carbide oilstone with a particle size of W5-W10, the raceway surface of the finely ground bearing outer ring is subjected to ultra-precision machining for 2 minutes under a pressure of 0.3MPa and an oscillation frequency of 1000 times / min.

[0055] S6. Cleaning: Place the ultra-finely ground bearing outer ring in the first cleaning tank and ultrasonically clean it for 3 minutes at 40 kHz and 1.2 W / cm² power density in an alkaline cleaning solution at 60 ℃. The alkaline cleaning solution includes the following components: 2.5 wt% silicate, 1.5 wt% nonionic surfactant, and 0.1 wt% benzotriazole, with the balance being water. The nonionic surfactant is fatty alcohol polyoxyethylene ether. Then, transfer the bearing outer ring to the second cleaning tank and ultrasonically rinse it for 2 minutes at 40 kHz and 0.6 W / cm² power density in flowing deionized water at 60 ℃. Finally, transfer the bearing outer ring to the third cleaning tank and ultrasonically clean it for 1 minute at 40 kHz and 0.6 W / cm² power density in deionized water with 0.3 wt% short-term rust inhibitor added at room temperature. After cleaning, dry it at 80 ℃ for 20 minutes.

[0056] Example 3

[0057] This application discloses a machining process for the outer ring of a bearing, including the following steps:

[0058] S1. Pretreatment: The outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted. The sandblasting steps are as follows: using cast steel shot with a diameter of 0.3-0.6 mm, the raceway area of ​​the outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted for 4 min under a pressure of 0.6 MPa. Then, using white corundum of 80-120 mesh, the non-raceway area of ​​the outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted for 4 min under a pressure of 0.3 MPa. Afterwards, the sandblasted outer ring of the bearing is placed in a water-based cleaning solution at 70℃. The water-based cleaning solution is a deionized aqueous solution containing 5 wt% amphoteric surfactant, wherein the amphoteric surfactant is a mixture of cocamidopropyl betaine and disodium lauroyl amphoteric diacetate with a mass ratio of 3:2. The ultrasonic cleaning is performed at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm² for 18 min, and then dried at 90℃ for 20 min.

[0059] S2. Surface nano-treatment: The pretreated bearing outer ring is fixed on a surface mechanical grinding equipment, with the raceway surface of the bearing outer ring facing the processing head. GCr15 steel balls with a diameter of 1-3mm are used as projectiles to impact the raceway surface at a speed of 45m / s. The feed speed of the processing head is 400mm / min, and the angle between the impact direction of the projectiles and the normal of the raceway surface is 30°. The treatment lasts for 20min.

[0060] S3. Rough grinding: The raceway is rough ground using a CBN grinding wheel with ceramic bond. The grit size of the CBN grinding wheel is 80 / 100-120 / 140, the grinding wheel linear speed is 70m / s, the workpiece rotation speed is 200rpm, and the radial feed rate is 0.02mm / stroke.

[0061] S4. Fine grinding: The raceway after rough grinding is finely ground using a CBN grinding wheel with resin bond. The grit size of the CBN grinding wheel is 170 / 200-230 / 270, the grinding wheel linear speed is 100m / s, the workpiece rotation speed is 350rpm, the radial feed is 0.004mm / stroke, and spark-free finishing is performed.

[0062] S5. Ultra-precision machining: Using silicon carbide oilstone with a particle size of W5-W10, the raceway surface of the finely ground bearing outer ring is subjected to ultra-precision machining for 4 minutes under a pressure of 0.2MPa and an oscillation frequency of 800 times / min.

[0063] S6. Cleaning: Place the ultra-finely ground bearing outer ring in the first cleaning tank and ultrasonically clean it for 4 minutes at 40 kHz and 1.2 W / cm² power density in an alkaline cleaning solution at 55 ℃. The alkaline cleaning solution includes the following components: 2 wt% silicate, 1 wt% nonionic surfactant, and 0.08 wt% benzotriazole, with the balance being water. The nonionic surfactant is fatty alcohol polyoxyethylene ether. Then, transfer the bearing outer ring to the second cleaning tank and ultrasonically rinse it for 3 minutes at 40 kHz and 0.6 W / cm² power density in flowing deionized water at 55 ℃. Finally, transfer the bearing outer ring to the third cleaning tank and ultrasonically clean it for 2 minutes at 40 kHz and 0.6 W / cm² power density in deionized water with 0.2 wt% short-term rust inhibitor added at room temperature. After cleaning, dry it at 70 ℃ for 25 minutes.

[0064] Example 4

[0065] The difference from Example 1 is that the composition of the water-based cleaning solution is different. The water-based cleaning solution includes the following components: 3 wt% amphoteric surfactant, 1 wt% glycerol, 0.5 wt% urea, and the balance is deionized water. The amphoteric surfactant is a mixture of cocamidopropyl betaine and disodium lauroyl amphoteric diacetate in a mass ratio of 3:2.

[0066] Example 5

[0067] The difference from Example 4 is that the method of step S1 is different.

[0068] S1. Pretreatment: The outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted. The sandblasting steps are as follows: using cast steel shot with a diameter of 0.3-0.6mm, the raceway area of ​​the outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted for 5 minutes under a pressure of 0.5MPa. Then, using white corundum of 80-120 mesh, the non-raceway area of ​​the outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted for 5 minutes under a pressure of 0.3MPa.

[0069] The sandblasted bearing outer ring was then immersed in a water-based cleaning solution and ultrasonically cleaned for 3 minutes at room temperature with an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². The cleaning solution was then heated to 60 ℃ at a rate of 1 ℃ / min and ultrasonically cleaned at a constant temperature with an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm² for 20 minutes. The bearing outer ring was then transferred to another tank of room temperature deionized water and ultrasonically cleaned for 2 minutes with an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². Finally, the bearing outer ring was transferred to a nitrogen-filled drying oven and dried at 80 ℃ for 25 minutes.

[0070] Example 6

[0071] The difference from Example 1 is that the method of step S1 is different.

[0072] S1. Pretreatment: The bearing outer ring, after quenching and low-temperature tempering heat treatment, is placed in liquid nitrogen at -196℃ and held for 1 hour. It is then allowed to return to room temperature in air before sandblasting. The sandblasting process involves: using cast steel shot with a diameter of 0.3-0.6mm, sandblasting the raceway area of ​​the quenched and low-temperature tempered bearing outer ring at a pressure of 0.5MPa for 5 minutes; then using 80-120 mesh white corundum, sandblasting the quenched and low-temperature tempered bearing outer ring at a pressure of 0.3MPa. The non-raceway area of ​​the outer ring of the bearing after treatment was sandblasted for 5 minutes. Then, the sandblasted outer ring of the bearing was placed in a water-based cleaning solution at 60°C. The water-based cleaning solution was a deionized aqueous solution containing 5 wt% amphoteric surfactant, wherein the amphoteric surfactant was a mixture of cocamidopropyl betaine and disodium lauroyl amphoteric diacetate in a mass ratio of 3:2. The ultrasonic cleaning was performed for 20 minutes at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm², and then dried at 80°C for 25 minutes.

[0073] Example 7

[0074] This application discloses a machining process for the outer ring of a bearing, including the following steps:

[0075] S1. Pretreatment: The bearing outer ring after quenching and low-temperature tempering heat treatment is placed in liquid nitrogen at -196℃ and kept at that temperature for 1 hour. Then it is restored to room temperature in air and then sandblasted. The sandblasting steps are as follows: using cast steel shot with a diameter of 0.3-0.6mm, the raceway area of ​​the bearing outer ring after quenching and low-temperature tempering heat treatment is sandblasted for 5 minutes under a pressure of 0.5MPa. Then, using white corundum of 80-120 mesh, the non-raceway area of ​​the bearing outer ring after quenching and low-temperature tempering heat treatment is sandblasted for 5 minutes under a pressure of 0.3MPa.

[0076] The sandblasted bearing outer ring was then immersed in a water-based cleaning solution, which consisted of the following components: 3 wt% amphoteric surfactant, 1 wt% glycerol, 0.5 wt% urea, and the remainder being deionized water. The amphoteric surfactant was a mixture of cocamidopropyl betaine and disodium lauroyl amphoteric diacetate in a mass ratio of 3:2. The mixture was ultrasonically cleaned for 3 minutes at room temperature, with an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². Then, the cleaning solution was heated to 60 ℃ at a rate of 1 ℃ / min, and ultrasonically cleaned at a constant temperature for 20 minutes at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². The bearing outer ring was then transferred to another tank of deionized water at room temperature and ultrasonically cleaned for 2 minutes at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². Finally, the bearing outer ring was transferred to a nitrogen-filled drying oven and dried at 80 ℃ for 25 minutes.

[0077] S2. Surface nano-treatment: The pretreated bearing outer ring is fixed on a surface mechanical grinding equipment, with the raceway surface of the bearing outer ring facing the processing head. GCr15 steel balls with a diameter of 1-3mm are used as projectiles to impact the raceway surface at a speed of 40m / s. The feed speed of the processing head is 300mm / min, and the angle between the impact direction of the projectiles and the normal of the raceway surface is 0°. The treatment lasts for 30min.

[0078] S3. Rough grinding: The raceway is rough ground using a CBN grinding wheel with ceramic bond. The grit size of the CBN grinding wheel is 80 / 100-120 / 140, the grinding wheel linear speed is 60m / s, the workpiece rotation speed is 100rpm, and the radial feed rate is 0.01mm / stroke.

[0079] S4. Fine grinding: The raceway after rough grinding is finely ground using a CBN grinding wheel with resin bond. The grit size of the CBN grinding wheel is 170 / 200-230 / 270, the grinding wheel linear speed is 80m / s, the workpiece rotation speed is 200rpm, the radial feed is 0.002mm / stroke, and spark-free finishing is performed.

[0080] S5. Ultra-precision machining: Using silicon carbide oilstone with a particle size of W5-W10, the raceway surface of the finely ground bearing outer ring is subjected to ultra-precision machining for 5 minutes under a pressure of 0.1MPa and an oscillation frequency of 500 times / min.

[0081] S6. Cleaning: Place the ultra-finely ground bearing outer ring in the first cleaning tank and ultrasonically clean it for 5 minutes at a frequency of 40 kHz and a power density of 1.2 W / cm² in an alkaline cleaning solution at a temperature of 50 ℃. The alkaline cleaning solution includes the following components: 1 wt% silicate, 0.5 wt% nonionic surfactant, and 0.05 wt% benzotriazole, with the balance being water. The nonionic surfactant is fatty alcohol polyoxyethylene ether. Then, transfer the bearing outer ring to the second cleaning tank and ultrasonically rinse it for 3 minutes at a frequency of 40 kHz and a power density of 0.6 W / cm² in flowing deionized water at a temperature of 50 ℃. Finally, transfer the bearing outer ring to the third cleaning tank and ultrasonically clean it for 2 minutes at a frequency of 40 kHz and a power density of 0.6 W / cm² in deionized water with 0.1 wt% short-term rust inhibitor added at room temperature. After cleaning, dry it at 60 ℃ for 30 minutes.

[0082] Example 8

[0083] This application discloses a machining process for the outer ring of a bearing, including the following steps:

[0084] S1. Pretreatment: The bearing outer ring after quenching and low-temperature tempering heat treatment is placed in liquid nitrogen at -196℃ and kept at that temperature for 3 hours. Then it is restored to room temperature in air and then sandblasted. The sandblasting steps are as follows: using cast steel shot with a diameter of 0.3-0.6mm, the raceway area of ​​the bearing outer ring after quenching and low-temperature tempering heat treatment is sandblasted for 2 minutes under a pressure of 0.7MPa. Then, using white corundum of 80-120 mesh, the non-raceway area of ​​the bearing outer ring after quenching and low-temperature tempering heat treatment is sandblasted for 2 minutes under a pressure of 0.4MPa.

[0085] The sandblasted bearing outer ring was then immersed in a water-based cleaning solution, which consisted of the following components: 5 wt% amphoteric surfactant, 2 wt% glycerol, 1.5 wt% urea, and the remainder being deionized water. The amphoteric surfactant was a mixture of cocamidopropyl betaine and disodium lauroyl amphoteric diacetate in a mass ratio of 3:2. The mixture was ultrasonically cleaned for 5 minutes at room temperature, at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². Then, the cleaning solution was heated to 75 ℃ at a rate of 2 ℃ / min, and ultrasonically cleaned at a constant temperature for 15 minutes at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². The bearing outer ring was then transferred to another tank of deionized water at room temperature and ultrasonically cleaned for 3 minutes at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². Finally, the bearing outer ring was transferred to a nitrogen-filled drying oven and dried at 100 ℃ for 15 minutes.

[0086] S2. Surface nano-treatment: The pretreated bearing outer ring is fixed on a surface mechanical grinding equipment, with the bearing outer ring raceway surface facing the processing head. GCr15 steel balls with a diameter of 1-3mm are used as projectiles to impact the raceway surface at a speed of 50m / s. The feed speed of the processing head is 500mm / min, and the angle between the projectile impact direction and the normal of the raceway surface is 45°. The treatment lasts for 10min.

[0087] S3. Rough grinding: The raceway is rough ground using a CBN grinding wheel with ceramic bond. The grit size of the CBN grinding wheel is 80 / 100-120 / 140, the grinding wheel linear speed is 80m / s, the workpiece rotation speed is 300rpm, and the radial feed rate is 0.02mm / stroke.

[0088] S4. Fine grinding: The raceway after rough grinding is finely ground using a CBN grinding wheel with resin bond. The grit size of the CBN grinding wheel is 170 / 200-230 / 270, the grinding wheel linear speed is 120m / s, the workpiece rotation speed is 500rpm, the radial feed is 0.005mm / stroke, and spark-free finishing is performed.

[0089] S5. Ultra-precision machining: Using silicon carbide oilstone with a particle size of W5-W10, the raceway surface of the finely ground bearing outer ring is subjected to ultra-precision machining for 2 minutes under a pressure of 0.3MPa and an oscillation frequency of 1000 times / min.

[0090] S6. Cleaning: Place the ultra-finely ground bearing outer ring in the first cleaning tank and ultrasonically clean it for 3 minutes at 40 kHz and 1.2 W / cm² power density in an alkaline cleaning solution at 60 ℃. The alkaline cleaning solution includes the following components: 2.5 wt% silicate, 1.5 wt% nonionic surfactant, and 0.1 wt% benzotriazole, with the balance being water. The nonionic surfactant is fatty alcohol polyoxyethylene ether. Then, transfer the bearing outer ring to the second cleaning tank and ultrasonically rinse it for 2 minutes at 40 kHz and 0.6 W / cm² power density in flowing deionized water at 60 ℃. Finally, transfer the bearing outer ring to the third cleaning tank and ultrasonically clean it for 1 minute at 40 kHz and 0.6 W / cm² power density in deionized water with 0.3 wt% short-term rust inhibitor added at room temperature. After cleaning, dry it at 80 ℃ for 20 minutes.

[0091] Example 9

[0092] This application discloses a machining process for the outer ring of a bearing, including the following steps:

[0093] S1. Pretreatment: The bearing outer ring after quenching and low-temperature tempering heat treatment is placed in liquid nitrogen at -196℃ and kept at that temperature for 2 hours. Then it is restored to room temperature in air and then sandblasted. The sandblasting steps are as follows: using cast steel shot with a diameter of 0.3-0.6mm, the raceway area of ​​the bearing outer ring after quenching and low-temperature tempering heat treatment is sandblasted for 4 minutes under a pressure of 0.6MPa. Then, using white corundum of 80-120 mesh, the non-raceway area of ​​the bearing outer ring after quenching and low-temperature tempering heat treatment is sandblasted for 4 minutes under a pressure of 0.3MPa.

[0094] The sandblasted bearing outer ring was then immersed in a water-based cleaning solution, which consisted of the following components: 4 wt% amphoteric surfactant, 1.5 wt% glycerol, 1 wt% urea, and the remainder being deionized water. The amphoteric surfactant was a mixture of cocamidopropyl betaine and disodium lauroyl amphoteric diacetate in a mass ratio of 3:2. The solution was ultrasonically cleaned for 3-5 minutes at room temperature, with an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². Then, the cleaning solution was heated to 70 ℃ at a rate of 1 ℃ / min, and ultrasonically cleaned at a constant temperature for 18 minutes at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². The bearing outer ring was then transferred to another tank of room temperature deionized water and ultrasonically cleaned for 2 minutes at an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². Finally, the bearing outer ring was transferred to a nitrogen-filled drying oven and dried at 90 ℃ for 20 minutes.

[0095] S2. Surface nano-treatment: The pretreated bearing outer ring is fixed on a surface mechanical grinding equipment, with the raceway surface of the bearing outer ring facing the processing head. GCr15 steel balls with a diameter of 1-3mm are used as projectiles to impact the raceway surface at a speed of 45m / s. The feed speed of the processing head is 400mm / min, and the angle between the impact direction of the projectiles and the normal of the raceway surface is 30°. The treatment lasts for 20min.

[0096] S3. Rough grinding: The raceway is rough ground using a CBN grinding wheel with ceramic bond. The grit size of the CBN grinding wheel is 80 / 100-120 / 140, the grinding wheel linear speed is 70m / s, the workpiece rotation speed is 200rpm, and the radial feed rate is 0.02mm / stroke.

[0097] S4. Fine grinding: The raceway after rough grinding is finely ground using a CBN grinding wheel with resin bond. The grit size of the CBN grinding wheel is 170 / 200-230 / 270, the grinding wheel linear speed is 100m / s, the workpiece rotation speed is 350rpm, the radial feed is 0.004mm / stroke, and spark-free finishing is performed.

[0098] S5. Ultra-precision machining: Using silicon carbide oilstone with a particle size of W5-W10, the raceway surface of the finely ground bearing outer ring is subjected to ultra-precision machining for 4 minutes under a pressure of 0.2MPa and an oscillation frequency of 800 times / min.

[0099] S6. Cleaning: Place the ultra-finely ground bearing outer ring in the first cleaning tank and ultrasonically clean it for 4 minutes at 40 kHz and 1.2 W / cm² power density in an alkaline cleaning solution at 55 ℃. The alkaline cleaning solution includes the following components: 2 wt% silicate, 1 wt% nonionic surfactant, and 0.08 wt% benzotriazole, with the balance being water. The nonionic surfactant is fatty alcohol polyoxyethylene ether. Then, transfer the bearing outer ring to the second cleaning tank and ultrasonically rinse it for 3 minutes at 40 kHz and 0.6 W / cm² power density in flowing deionized water at 55 ℃. Finally, transfer the bearing outer ring to the third cleaning tank and ultrasonically clean it for 2 minutes at 40 kHz and 0.6 W / cm² power density in deionized water with 0.2 wt% short-term rust inhibitor added at room temperature. After cleaning, dry it at 70 ℃ for 25 minutes.

[0100] Example 10

[0101] The difference from Example 1 is that the method of step S1 is different.

[0102] S1. Pretreatment: The outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted. The sandblasting steps are as follows: using cast steel shot with a diameter of 0.3-0.6mm, the raceway area of ​​the outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted for 5 minutes under a pressure of 0.5MPa. Then, using white corundum of 80-120 mesh, the non-raceway area of ​​the outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted for 5 minutes under a pressure of 0.3MPa.

[0103] The sandblasted bearing outer ring was then immersed in a water-based cleaning solution and ultrasonically cleaned for 3 minutes at room temperature with an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². The cleaning solution was then heated to 60 ℃ at a rate of 1 ℃ / min and ultrasonically cleaned at a constant temperature with an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm² for 20 minutes. The bearing outer ring was then transferred to another tank of room temperature deionized water and ultrasonically cleaned for 2 minutes with an ultrasonic frequency of 40 kHz and a power density of 1.0 W / cm². Finally, the bearing outer ring was transferred to a nitrogen-filled drying oven and dried at 80 ℃ for 25 minutes.

[0104] Comparative Example 1

[0105] The difference from Example 1 is that step S2 is omitted, serving as a blank control group.

[0106] Performance testing

[0107] (1) Wear resistance test: Examples 1-10 and Comparative Example 1 were tested according to the standard GB / T 12444-2006 "Metallic Materials Wear Test Method Test Ring-Block Sliding Wear Test". A standard GCr15 steel ring (hardness 62±1HRC) was used as the wear test piece. 10mm×10mm×5mm test blocks were cut from the outer ring raceway of the bearings in Examples 1-10 and Comparative Example 1 as the test samples. The test load was 200N, the sliding speed was 0.5m / s, and the total sliding distance was 1600m. The L-AN32 total loss system was used for drip lubrication. The volume wear was recorded. Each set of data was tested 3 times and the average value was taken. The test results are shown in Table 1 below.

[0108] (2) Hardness test: Examples 1-10 and Comparative Example 1 were tested according to standard GB / T 4340.1-2024 "Metallic materials Vickers hardness test - Part 1: Test method". On the cross section of the sample perpendicular to the raceway surface, a micro Vickers hardness tester was used with a test force of 0.9807 N (100 gf) to test point by point from about 20 μm below the surface. Within a depth of 150 μm from the surface, the test was conducted densely at intervals of 20 μm. Then the interval was increased to 50 μm until the hardness value tended to stabilize. The holding time was 15 s. The hardness of the three effective test points closest to the surface was taken and the average value was calculated as the representative value of surface hardness (HV0.1). Each group of samples was tested at least three radial sections with a mutual interval of 120°. The average value of the results was taken. The test results are shown in Table 1 below.

[0109] Table 1 Performance Test Results

[0110] Volume wear (mm³) Surface hardness (HV0.1) Example 1 4.14 876 Example 2 4.07 886 Example 3 4.01 897 Example 4 3.28 920 Example 5 2.94 939 Example 6 2.68 981 Example 7 1.87 1063 Example 8 1.79 1075 Example 9 1.68 1082 Example 10 4.03 885 Comparative Example 1 6.78 782

[0111] In conclusion, the following conclusions can be drawn:

[0112] 1. As can be seen from Examples 1-3 and Comparative Example 1 and Table 1, introducing a surface nano-treatment process before grinding can improve the surface hardness and wear resistance of the bearing outer ring. The reason may be that the repeated impact of high-speed shot on the raceway surface induces severe plastic deformation on the surface layer, thereby forming a gradient nanocrystalline structure layer that transitions from surface nanocrystals to coarse grains in the core. The gradient nanocrystalline structure layer has extremely high hardness and strength, which enhances the material's ability to resist grinding, thereby reducing the grinding force and grinding heat generated during subsequent rough and fine grinding, and inhibiting the generation of thermal damage and phase transformation. On the other hand, the nano-treatment process pre-forms stable and deep residual compressive stress on the surface layer, which can offset the harmful tensile stress generated by subsequent grinding, so that the final raceway surface layer is stabilized in a beneficial compressive stress state or an extremely low tensile stress level, resulting in a high-hardness and low-damage high-quality working surface layer.

[0113] 2. As can be seen from Examples 1 and 4 and Table 1, using a water-based cleaning solution containing glycerol and urea is beneficial to improving the surface hardness and wear resistance of the bearing outer ring. The reason may be that urea can undergo hydrolysis and generate active nitrogen species under the combined action of ultrasound and heating. At the same time, glycerol may decompose in the hot spot of local high temperature and high pressure generated by ultrasonic cavitation, providing active carbon species. Under the stirring and impact provided by the ultrasonic cavitation effect, these active nitrogen and active carbon can be adsorbed and slightly penetrate into the highly active raceway surface after sandblasting. In the subsequent surface nano-sizing treatment, these penetrated nitrogen and carbon atoms, as interstitial atoms, can become dislocation pinning centers, promote dislocation entanglement and recombination, thereby driving grain refinement more efficiently and forming a finer and more uniform gradient nanocrystalline structure layer under the same process conditions.

[0114] 3. Combining Examples 1, 4, 5, and 10 with Table 1, it can be seen that the programmed control of room temperature ultrasonic cleaning - heating activation - rapid cooling rinsing termination - inert atmosphere drying can further optimize the surface hardness and wear resistance of the bearing outer ring. The reason may be that: room temperature ultrasonic cleaning uses cavitation and wetting to remove sandblasting residues, avoiding the sintering of contaminants at high temperatures in the future; gradient heating ensures that the workpiece and cleaning solution are heated evenly, preventing thermal shock and ensuring uniform surface reaction; the constant temperature ultrasonic section maintains the reaction temperature and mass transfer, promoting the uniform adsorption and penetration of active nitrogen and carbon species on the surface; after activation, it is immediately transferred to room temperature deionized water ultrasonic rinsing, which can quickly terminate the reaction, prevent over-treatment, and use temperature difference and ultrasound to remove residues in synergy; drying under nitrogen protection can isolate oxygen, maintain the high chemical activity of the surface layer, avoid oxidation, and ensure that the workpiece enters the subsequent nano-processing process with a clean and activated surface.

[0115] 4. As can be seen from Examples 1 and 6 and Table 1, cryogenic treatment of the bearing outer ring before sandblasting can improve the surface hardness and wear resistance of the bearing outer ring. The reason may be that cryogenic treatment drives the transformation of residual austenite to martensite and promotes the precipitation of dispersed fine carbides in the matrix, which improves the overall hardness, dimensional stability and matrix strength of the material. At the same time, this treatment introduces crystal defects such as high-density dislocations and twins, so that in the subsequent sandblasting process, the impact energy can be more concentrated on driving the proliferation and interaction of pre-existing defects on the surface to form a pre-activated layer of high-density dislocations, rather than being absorbed by the plastic deformation of the matrix. Thus, under the same surface nano-sizing process parameters, it can more efficiently promote dislocation entanglement and grain boundary reorganization, and obtain a gradient nanocrystalline reinforced layer with finer grains, greater thickness and more uniform structure, while maintaining high dimensional stability and improving the wear resistance of the raceway surface.

[0116] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A machining process for a bearing outer ring, characterized in that, Includes the following steps: S1. Pretreatment: The outer ring of the bearing after quenching and low-temperature tempering heat treatment is sandblasted. Then, the sandblasted outer ring is immersed in a water-based cleaning solution and ultrasonically cleaned at room temperature for 3-5 minutes. Then, the cleaning solution is heated to 60-75℃ at a rate of 1-2℃ / min and ultrasonically cleaned at a constant temperature for 15-20 minutes. The outer ring of the bearing is then transferred to another tank of deionized water at room temperature and ultrasonically cleaned for 2-3 minutes. Finally, the outer ring of the bearing is transferred to a drying oven filled with nitrogen and dried at 80-100℃ for 15-25 minutes. The water-based cleaning solution includes the following components: 3-5wt% amphoteric surfactant, 1-2wt% glycerol, 0.5-1.5wt% urea, and the balance is deionized water. S2. Surface nano-treatment: The pretreated bearing outer ring is fixed on a surface mechanical grinding equipment, with the bearing outer ring raceway surface facing the processing head. GCr15 steel balls with a diameter of 1-3mm are used as projectiles to impact the raceway surface at a speed of 40-50m / s. The feed speed of the processing head is 300-500mm / min, and the angle between the projectile impact direction and the normal of the raceway surface is 0°-45°. The treatment time is 10-30min. S3. Rough grinding: The raceway is rough ground using a CBN grinding wheel with ceramic bond. The grit size of the CBN grinding wheel is 80 / 100-120 / 140, the grinding wheel linear speed is 60-80m / s, the workpiece rotation speed is 100-300rpm, and the radial feed rate is 0.01-0.02mm / stroke. S4. Fine grinding: The raceway after rough grinding is finely ground using a CBN grinding wheel with resin bond. The grit size of the CBN grinding wheel is 170 / 200-230 / 270, the grinding wheel linear speed is 80-120m / s, the workpiece rotation speed is 200-500rpm, the radial feed is 0.002-0.005mm / stroke, and spark-free finishing is performed. S5. Ultra-precision machining: Using silicon carbide oilstone with a particle size of W5-W10, the raceway surface of the finely ground bearing outer ring is subjected to ultra-precision machining for 2-5 minutes under a pressure of 0.1-0.3MPa and an oscillation frequency of 500-1000 times / min. S6. Cleaning: Place the ultra-finely ground bearing outer ring in the first cleaning tank and ultrasonically clean it for 3-5 minutes in an alkaline cleaning solution at 50-60℃. Then transfer the bearing outer ring to the second cleaning tank and ultrasonically rinse it for 2-3 minutes in flowing deionized water at 50-60℃. Finally, transfer the bearing outer ring to the third cleaning tank and ultrasonically clean it for 1-2 minutes in deionized water at room temperature with 0.1-0.3wt% short-term rust inhibitor added. After cleaning, dry it at 60-80℃ for 20-30 minutes.

2. The machining process of the bearing outer ring according to claim 1, characterized in that: The amphoteric surfactant is a mixture of cocamidopropyl betaine and disodium lauroyl amphoteric diacetate in a mass ratio of 3:

2.

3. The machining process of the bearing outer ring according to claim 1, characterized in that: In step S1, the outer ring of the bearing, after being quenched and tempered at low temperature, is placed in liquid nitrogen at -196°C and kept at that temperature for 1-3 hours. Then, it is allowed to return to room temperature in the air before being sandblasted cleaned.

4. The machining process of the bearing outer ring according to claim 3, characterized in that: In step S1, the sandblasting cleaning process is as follows: using cast steel shot with a diameter of 0.3-0.6 mm, sandblasting the raceway area of ​​the bearing outer ring after quenching and low-temperature tempering heat treatment for 2-5 minutes under a pressure of 0.5-0.7 MPa; then using white corundum of 80-120 mesh, sandblasting the non-raceway area of ​​the bearing outer ring after quenching and low-temperature tempering heat treatment for 2-5 minutes under a pressure of 0.3-0.4 MPa.

5. The machining process of the bearing outer ring according to claim 1, characterized in that: The alkaline cleaning solution comprises the following components: 1-2.5 wt% silicate, 0.5-1.5 wt% nonionic surfactant and 0.05-0.1 wt% benzotriazole, with the balance being water.

6. The machining process of the bearing outer ring according to claim 5, characterized in that: The nonionic surfactant is a fatty alcohol polyoxyethylene ether.