Needle bearing surface strengthening treatment method

Abstract

The invention discloses a needle bearing surface strengthening treatment method, which relates to the field of needle bearings, and comprises the following steps: S1, a pretreatment stage; s2, surface strengthening core process: selecting a heavy-load working condition strengthening route or a precise / thin-wall bearing strengthening route according to the service working condition of the needle bearing; and S3, a post-treatment finishing stage. According to the method, multiple technologies such as heat treatment (carburizing and quenching and gas nitriding), mechanical strengthening (shot blasting) and surface coating (PVD-TiN and DLC) are systematically combined, and a multi-dimensional strengthening system is formed. All the processes cooperate with one another, so that the surface of the bearing has high hardness, fatigue resistance, low friction and corrosion resistance at the same time, the performance limitation of a single process is broken through, the comprehensive performance of the needle bearing is remarkably improved, meanwhile, a targeted strengthening scheme is customized according to different service conditions of the needle bearing, and the service life of the needle bearing is prolonged. And the high-performance requirements of the needle bearing under different working conditions are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of needle bearing, in particular to a needle bearing surface strengthening treatment method. BACKGROUND

[0002] As a key component in mechanical equipment, the performance of needle bearing directly affects the operation reliability and service life of the equipment. In practical applications, needle bearings often face complex working conditions such as heavy load, high speed, strong corrosion, etc., which puts high requirements on the hardness, wear resistance, fatigue resistance and corrosion resistance of the bearing surface.

[0003] At present, the common needle bearing surface strengthening treatment method mostly adopts a single technology, such as carburizing quenching, gas nitriding, shot peening or surface coating, etc. However, the single process has obvious limitations: carburizing quenching can improve the surface hardness, but the corrosion resistance is poor; gas nitriding can improve the wear resistance, but the bearing size is prone to slight deformation after treatment; shot peening can enhance the fatigue resistance, but the improvement of hardness and corrosion resistance is limited; surface coating has the functions of reducing friction and preventing corrosion, but the bonding force between the coating and the substrate is insufficient, and the coating peeling phenomenon is easy to occur. Therefore, the existing treatment method is difficult to meet the high performance requirements of needle bearings under complex working conditions. SUMMARY

[0004] The purpose of the present application is to provide a needle bearing surface strengthening treatment method to solve the problems raised in the background art.

[0005] To achieve the above purpose, the present application provides the following technical scheme: a needle bearing surface strengthening treatment method, comprising the following steps:

[0006] S1, pretreatment stage: using a three-tank ultrasonic cleaning machine to sequentially clean the needle bearing with an alkaline water-based cleaning agent, ultrasonic oil removal, deionized water rinsing and acetone or ethanol dehydration; placing the cleaned bearing in a vacuum drying oven for vacuum drying and surface activation;

[0007] S2, surface strengthening core process: according to the service conditions of the needle bearing, selecting a heavy load condition strengthening route or a precision / thin-walled bearing strengthening route;

[0008] S3, post-treatment finishing stage: chemically and mechanically polishing the bearing after strengthening treatment, and conducting full-item quality detection.

[0009] Preferably, the heavy load condition strengthening route specifically includes:

[0010] A1, low-pressure vacuum carburizing quenching: the bearing is placed in a vacuum carburizing furnace, heated to 930℃ at a rate of 10℃ / min, pulse type C3H8 and Ar mixed gas is introduced, the carbon potential is controlled at 1.2%-1.4%, the cycle operation of strong penetration 15min+diffusion 10min is carried out for 8 times; when quenching, enter the gas quenching chamber, cool with 2MPa nitrogen, the cooling rate is ≥50℃ / s to 150℃; the tempering stage is at 180℃±5℃ for 2h;

[0011] A2, numerical control shot peening: using numerical control turret peening machine, using cast steel shot, the jet speed is 80-100m / s, the coverage is controlled by Almen test piece, the arc height value is 0.3-0.5mm, the coverage is ≥98%, the jet angle is 45°-60° alternate jet;

[0012] A3, PVD-TiN coating deposition: in a multi-arc ion plating machine, first perform Ar⁺ ion flow bombardment cleaning, then perform coating deposition, Ti target arc flow 80-100A, N2 flow 50-80sccm, substrate bias -100V, temperature 180-200℃ for 90min.

[0013] Preferably, the precise / thin-wall bearing strengthening route specifically includes:

[0014] B1, low-temperature ion nitriding: the bearing is placed in a direct current plasma nitriding furnace, heated to 560℃ at a rate of 5℃ / min, ammonia flow 200sccm, furnace pressure 300Pa; during the nitriding stage, pulse duty ratio 40%-60%, voltage 500-600V, temperature 15h; during the cooling stage, cool down to below 150℃ under nitrogen protection;

[0015] B2, magnetron sputtering DLC coating: using a non-equilibrium magnetron sputtering coating machine, first perform sand blasting roughening treatment, then perform coating deposition, C target power 300W, Ar flow 30sccm, substrate bias -200V, temperature ≤150℃, deposition 120min.

[0016] Preferably, in the pretreatment stage, the concentration of alkaline water-based cleaning agent is 5%-8%, the temperature is 60-70℃, the ultrasonic cleaning time is 10-15min; the limit vacuum degree of the vacuum drying box is ≤10Pa, the small bearings are kept at 80-100℃ for 30min, and the large bearings are kept for 60min, the vacuum degree is maintained below 5Pa.

[0017] Preferably, after low-pressure vacuum carburizing quenching, the carburizing layer depth needs to reach 0.8-1.0mm, the surface layer martensite level is ≤3; after the numerical control shot peening, the surface layer residual compressive stress needs to reach -600±100MPa; the PVD-TiN coating thickness needs to reach 2.0-2.5μm, the adhesion needs to meet 1mm spacing without peeling through the grid method.

[0018] Preferably, after low-temperature ion nitriding, the white layer is less than or equal to 5 microns in metallographic detection, the compound layer is continuous and uniform, and the substrate has no obvious decarburization; the hardness of the magnetron sputtering DLC coating needs to reach HV greater than or equal to 2500, and the friction coefficient is less than or equal to 0.08.

[0019] Preferably, the chemical mechanical polishing adopts a double-sided polishing machine, the polishing liquid is 5% SiO2 nano slurry with pH = 10, the pressure of small bearings is controlled at 0.2-0.3 MPa, the pressure of large bearings is 0.5-0.8 MPa, and the polishing time is 15-30 minutes, and the final surface roughness Ra is less than or equal to 0.15 microns.

[0020] Preferably, the whole project quality detection includes: detecting the size accuracy by a three-coordinate measuring machine, which needs to meet the GB / T307.1 tolerance grade IT3-IT5; detecting the surface hardness by a Vickers microhardness tester, the carburized layer is greater than or equal to 600 HV, and the nitrided layer is greater than or equal to 850 HV; detecting the coating adhesion by a scratch method, the critical load is greater than or equal to 8 N, and there is no coating peeling; testing the fatigue life by a rotary bending fatigue testing machine, the average life is greater than or equal to 5*10 6

[0021] Preferably, it also includes a process control step: using an RFID tag to trace each bearing throughout the whole process, recording the furnace number, process parameters and detection data; establishing an SPC control chart to monitor the key process parameters; automatically triggering the rework process for batches with excessive differences, and the rework limit is 2 times.

[0022] Compared with the prior art, the beneficial effects of the present application are:

[0023] 1. In the present application, heat treatment (carburizing and quenching, gas nitriding), mechanical strengthening (shot peening) and surface coating (PVD-TiN, DLC) and other processes are systematically combined to form a multi-dimensional strengthening system. Each process cooperates with each other, so that the bearing surface simultaneously obtains high hardness, fatigue resistance, low friction and corrosion resistance, breaking through the performance limitations of single process, and significantly improving the comprehensive performance of the needle bearing.

[0024] 2. In the present application, according to different service conditions (heavy load, high precision, high speed corrosion, etc.) of the needle bearing, a targeted strengthening scheme is customized. For example, for heavy load working conditions, "carburizing and quenching + shot peening + TiN coating" is adopted, and for precision thin-walled bearings, "ion nitriding + DLC coating" is adopted, realizing deep coupling of process parameters and actual working conditions, and maximizing the strengthening effect through accurate matching of "material - process - performance", meeting the high performance requirements of needle bearings under different working conditions.

[0025] ​3、The strict quality detection link and process control points are arranged in the whole processing flow in the application. The SPC control chart is established to monitor the key process parameters, such as the carburized layer depth CPK≥1.33; the RFID tag is used to trace each bearing in the whole flow, and the furnace number, process parameters, detection data and other information are recorded, and the storage period is up to 10 years; the rework flow is automatically triggered for the out-of-tolerance batch (limited to 2 times), and the waste gas and waste liquid are treated by taking environmental protection measures, so that the stability, traceability and environmental protection of the production process are ensured, and the product quality and production efficiency are effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The process flow chart of the needle bearing surface strengthening treatment method is shown in the application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0028] Embodiment: Refer to Figure 1 The needle bearing surface strengthening treatment method comprises the following steps:

[0029] I. Pretreatment stage: cleanliness and surface activation treatment.

[0030] (1) Ultrasonic cleaning of oil (key pretreatment process), specifically:

[0031] 1. The equipment and tooling adopt a three-tank ultrasonic cleaning machine (frequency 40 kHz, configured with a hanging net-shaped tooling basket with a pore diameter ≥5 mm), to ensure that the bearings have no stacking dead angle.

[0032] 2. Process steps: first tank (oil removal): inject 5%-8% alkaline water-based cleaning agent (temperature 60-70℃), ultrasonic cleaning for 10-15 minutes, to remove mineral oil, processing liquid and other impurities.

[0033] Second tank (rinsing): replace the deionized water, ultrasonic rinsing for 5 minutes, to remove the residual cleaning agent.

[0034] Third tank (dehydration): use acetone or ethanol, ultrasonic treatment for 3 minutes, to replace the water on the bearing surface.

[0035] Quality control: after drying, wipe the surface with a white cotton cloth, without oil stains remaining; through the contact angle measuring instrument, the surface contact angle needs to be <30° (hydrophilicity meets the standard).

[0036] (II) Vacuum drying and surface activation, in particular:

[0037] 1. Equipment vacuum drying oven (limiting vacuum degree ≤ 10 Pa), equipped with temperature automatic control system.

[0038] 2. Process parameters: small bearings: 80-100℃ for 30 minutes, vacuum degree maintained below 5 Pa.

[0039] Large bearings: same temperature for 60 minutes, ensure complete evaporation of internal pore moisture.

[0040] Operation points After drying, immediately transfer to the next process to avoid secondary surface contamination (interval time ≤ 15 minutes).

[0041] II. Surface strengthening core process: customized processing route according to working conditions.

[0042] (I) Strengthening route for heavy load working conditions (suitable for 20CrMnTi and other carburizing steels), in particular:

[0043] 1. Low-pressure vacuum carburizing and quenching (improve surface hardness and wear resistance), including:

[0044] Equipment: vacuum carburizing furnace (limiting vacuum degree 10⁻³ Pa, equipped with high-pressure gas quenching system);

[0045] Process parameters: heating stage: 10℃ / min to 930℃, vacuum degree 50 Pa;

[0046] Carburizing stage: pulse type C3H8 (propane) + Ar mixed gas (flow ratio 1:5) is introduced, carbon potential 1.2%-1.4%, strong penetration 15min + diffusion 10min, cycle 8 times;

[0047] Quenching stage: directly transfer to gas quenching chamber, 2MPa nitrogen cooling (cooling rate ≥ 50℃ / s to 150℃);

[0048] Tempering stage: 180℃±5℃ for 2h, air cooling to room temperature;

[0049] Detection standard: carburized layer depth 0.8-1.0mm (metallographic method), surface martensite level ≤ 3 (GB / T22562).

[0050] 2. Numerical control shot peening strengthening (anti-fatigue core process), including:

[0051] Equipment: numerical control rotary table shot peening machine (with shot recycling and circulating system);

[0052] Process parameters: Projectile: cast steel shot (S110, hardness 40-50HRC), injection speed 80-100m / s;

[0053] Coverage: controlled by Almen test piece (N type), arc height value 0.3-0.5mm, coverage rate ≥98% under microscope observation;

[0054] Injection angle: 45°-60° alternate injection, single bearing processing time 30-60s (calculated according to surface area);

[0055] Stress detection: X-ray diffractometer measurement, surface residual compressive stress needs to reach -600±100MPa.

[0056] 3. PVD-TiN coating deposition (wear-resistant and corrosion-resistant superposition), wherein:

[0057] Equipment: multi-arc ion plating machine (equipped with 4 or more Ti targets);

[0058] Process steps: ion bombardment cleaning: Ar+ ion flow (voltage 800V) treatment for 10 minutes to remove surface oxide film;

[0059] Coating deposition: Ti target arc flow 80-100A, N2 flow 50-80sccm, substrate bias -100V, 180-200℃ for 90 minutes;

[0060] Quality index: coating thickness 2.0-2.5μm (measured by coulomb method), grid method to detect the bonding force (ISO 2409, 1mm spacing without peeling).

[0061] (II) Strengthening route for precision / thin-walled bearings (suitable for GCr15 bearing steel), specifically:

[0062] 1. Low-temperature ion nitriding (low-deformation strengthening), wherein:

[0063] Equipment: direct current plasma nitriding furnace (pulse power, frequency 1-10kHz).

[0064] Process parameters: temperature rising stage: 5℃ / min to 560℃, ammonia flow 200sccm, furnace pressure 300Pa.

[0065] Nitriding stage: pulse duty cycle 40%-60%, voltage 500-600V, holding time 15h (nitriding layer depth 0.3-0.4mm).

[0066] Cooling stage: nitrogen protection furnace cooling to below 150℃.

[0067] Organizational requirements: metallographic detection white layer ≤5 μm, compound layer continuous and uniform, substrate without obvious decarburization.

[0068] 2. Magnetron sputtering DLC coating (super-lubrication treatment), wherein:

[0069] Equipment: non-equilibrium magnetron sputtering coating machine (equipped with C target).

[0070] Process steps: sandblasting roughening: 50-100 μm Al2O3 sand particles (0.3 MPa pressure) treatment for 10 s, to enhance the adhesion of the coating.

[0071] Coating deposition: C target power 300 W, Ar flow rate 30 sccm, substrate bias -200 V, temperature ≤150℃, deposition for 120 minutes.

[0072] Performance indicators: hardness HV≥2500, friction coefficient (ball-on-disc test) ≤0.08 (in the presence of lubricating grease).

[0073] III. Post-processing finishing stage: precision recovery and quality verification.

[0074] (1) Chemical mechanical polishing (dimensional accuracy control), specifically:

[0075] 1. Equipment: double-sided polishing machine (speed difference 10-15 rpm).

[0076] 2. Process parameters: polishing liquid: 5% SiO2 nano slurry (pH=10).

[0077] Pressure control: small bearings 0.2-0.3 MPa, large bearings 0.5-0.8 MPa.

[0078] Time: 15-30 minutes, final surface roughness Ra≤0.15 μm (stylus profilometer detection).

[0079] (2) Full project quality testing.

[0080] Detection item Detection method Acceptance criteria Dimensional accuracy Three-coordinate measuring machine Comply with GB / T 307.1 tolerance grade IT3-IT5 Surface hardness Vickers microhardness tester (0.3 kg load) Carburized layer ≥ 600HV, nitrided layer ≥ 850HV Coating adhesion Scratch method (load 10N) Critical load ≥ 8N, no coating peeling Fatigue life Rotary bending fatigue testing machine Mean life ≥ 5 x 10 6 times (1.5 times rated load) Salt spray corrosion resistance NSS neutral salt spray chamber (GB / T 10125) 48h no red rust (coating process must be tested)

[0081] IV. Process route decision and process control.

[0082] (1) Working condition adaptation matrix.

[0083] Service conditions Core process combination Key control parameters Typical application scenarios Heavy load + impact Carburizing and quenching → shot peening → TiN coating Carburized layer depth ≥ 0.8mm, shot peening coverage rate 98% Engineering machinery, mining machinery High precision + low speed Ion nitriding → DLC coating Nitriding temperature ≤ 580℃, coating thickness 1-2μm Precision instruments, medical equipment High speed + corrosion Low temperature nitriding → magnetron sputtering TiN coating Coating friction coefficient ≤ 0.25, salt spray ≥ 72h Aerospace, marine equipment

[0084] (2) Key points of production process control:

[0085] 1. Traceability system: each bearing is pasted with an RFID tag, recording furnace number, process parameters, and detection data (storage period 10 years).

[0086] 2. Abnormal processing: Establish SPC control chart (such as carburizing layer depth CPK≥1.33), out-of-tolerance batch triggers rework (limited to 2 times).

[0087] 3. Environmental protection measures: carburizing waste gas is treated by catalytic combustion (VOC removal rate≥95%), waste acid liquid is discharged after neutralization and precipitation (pH 6-9).

[0088] Through the above-mentioned whole process control, the surface hardness, fatigue resistance and corrosion resistance of the needle bearing can be systematically improved, the performance index achievement rate under different working conditions is≥99%, and the first-time inspection qualified rate of the key working procedure is≥95%. In actual production, the process parameters need to be adjusted according to the characteristics of the equipment, and it is suggested to establish a process database for continuous optimization.

[0089] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for surface strengthening treatment of needle roller bearings, characterized in that, Includes the following steps: S1. Pretreatment stage: The needle roller bearing is subjected to ultrasonic degreasing with alkaline water-based cleaning agent, rinsing with deionized water and dehydration with acetone or ethanol in sequence using a three-tank ultrasonic cleaner; the cleaned bearing is then placed in a vacuum drying oven for vacuum drying and surface activation. S2. Surface strengthening core process: Select the strengthening route for heavy load conditions or the strengthening route for precision / thin wall bearings according to the service conditions of the needle roller bearing. S3. Post-processing finishing stage: The reinforced bearings are chemically and mechanically polished and then pass the full-item quality inspection.

2. The surface strengthening treatment method for needle roller bearings according to claim 1, characterized in that: The enhancement strategy for heavy-load conditions includes: A1. Low-pressure vacuum carburizing and quenching: Place the bearing in a vacuum carburizing furnace and heat it to 930℃ at a rate of 10℃ / min. Pulse-introduce a mixture of C3H8 and Ar gas, control the carbon potential at 1.2%-1.4%, and perform a cycle of strong carburizing for 15min + diffusion for 10min, for a total of 8 cycles. During quenching, transfer it to a gas quenching chamber and cool it with 2MPa nitrogen gas at a cooling rate of ≥50℃ / s to 150℃. During the tempering stage, hold it at 180℃±5℃ for 2h. A2. CNC shot peening strengthening: CNC rotary table shot peening machine is used, cast steel shot is used, the blasting speed is 80-100m / s, the coverage is controlled by Almen test pieces, the arc height value is 0.3-0.5mm, the coverage is ≥98%, and the blasting angle is 45°-60° alternating blasting. A3. PVD-TiN Coating Deposition: In a multi-arc ion plating machine, Ar⁺ ion current bombardment cleaning is performed first, followed by coating deposition. The Ti target arc current is 80-100A, the N2 flow rate is 50-80sccm, the substrate bias voltage is -100V, and the temperature is maintained at 180-200℃ for 90 minutes.

3. The surface strengthening treatment method for needle roller bearings according to claim 1, characterized in that: The reinforcement routes for precision / thin-wall bearings include: B1. Low-temperature ion nitriding: Place the bearing in a DC plasma nitriding furnace and heat it to 560°C at a rate of 5°C / min. The ammonia flow rate is 200 sccm and the furnace pressure is 300 Pa. During the nitriding stage, the pulse duty cycle is 40%-60% and the voltage is 500-600 V. The temperature is held for 15 hours. During the cooling stage, the bearing is cooled to below 150°C under nitrogen protection. B2. Magnetron sputtering DLC ​​coating: Using an unbalanced magnetron sputtering coating machine, the coating is first roughened by sandblasting, and then deposited. The target power is 300W, the Ar flow rate is 30sccm, the substrate bias is -200V, the temperature is ≤150℃, and the deposition time is 120 minutes.

4. The surface strengthening treatment method for needle roller bearings according to claim 2, characterized in that: During the pretreatment stage, the concentration of alkaline water-based cleaning agent is 5%-8%, the temperature is 60-70℃, and the ultrasonic cleaning time is 10-15 minutes; the ultimate vacuum degree of the vacuum drying oven is ≤10Pa, small bearings are kept at 80-100℃ for 30 minutes, large bearings are kept at 60 minutes, and the vacuum degree is maintained below 5Pa.

5. The surface strengthening treatment method for needle roller bearings according to claim 4, characterized in that: After low-pressure vacuum carburizing and quenching, the carburized layer depth needs to reach 0.8-1.0 mm, and the surface martensite level ≤ 3; after CNC shot peening, the surface residual compressive stress needs to reach -600±100 MPa; the PVD-TiN coating thickness needs to reach 2.0-2.5 μm, and the adhesion strength tested by cross-cut test needs to meet the requirement of no peeling at a 1 mm interval.

6. The surface strengthening treatment method for needle roller bearings according to claim 1, characterized in that: After low-temperature ion nitriding, metallographic examination shows that the bright white layer is ≤5μm, the compound layer is continuous and uniform, and the substrate shows no obvious decarburization; the hardness of the magnetron sputtered DLC coating needs to reach HV≥2500 and the coefficient of friction ≤0.

08.

7. The surface strengthening treatment method for needle roller bearings according to claim 1, characterized in that: Chemical mechanical polishing uses a double-sided polishing machine, with a polishing slurry of 5% SiO2 nano-slurry, pH=10. The pressure is controlled at 0.2-0.3MPa for small bearings and 0.5-0.8MPa for large bearings. The polishing time is 15-30 minutes, and the final surface roughness Ra≤0.15μm.

8. The surface strengthening treatment method for needle roller bearings according to claim 3, characterized in that: The comprehensive quality inspection includes: dimensional accuracy testing using a coordinate measuring machine (CMM) to ensure it meets GB / T307.1 tolerance grades IT3-IT5; surface hardness testing using a Vickers microhardness tester, with carburized layers ≥600HV and nitrided layers ≥850HV; coating adhesion testing using the scratch test, with a critical load ≥8N and no coating peeling; and fatigue life testing using a rotary bending fatigue tester, with an average life ≥5×10⁻⁶. 6 The salt spray corrosion resistance test was conducted in an NSS neutral salt spray chamber, and no red rust was observed after 48 hours.

9. A surface strengthening treatment method for needle roller bearings according to claim 8, characterized in that: It also includes process control steps: using RFID tags to trace each bearing throughout the entire process, recording furnace number, process parameters, and test data; establishing SPC control charts to monitor key process parameters; and automatically triggering rework processes for batches that exceed tolerances, with a limit of 2 reworks.

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