Production method of front and rear ring bearing inner rings
阅读说明：本技术 前后环轴承内圈生产方法 (Production method of front and rear ring bearing inner rings ) 是由 孙小丛 高黛华 夏国顺 张必泉 李文喜 于 2019-10-16 设计创作，主要内容包括：一种前后环轴承内圈生产方法,用于前后环轴承新材料新工艺应用及生产固化。轴承内圈采用熔模精密铸造合金钢基材经熔模精密铸造成形,轴承沟道采用激光熔敷纳米合金粉材料,经数控车铣复合中心加工及数控成形磨削后,整体采用镀黑锌处理,盐雾试验需达到200小时。本发明采用精密熔模精密铸造工艺,可有效提高轴承内圈尺寸精度和表面粗糙度,以及材料利用率；轴承沟道的熔敷采用高机械性能、高耐磨性、防锈蚀的合金纳米粉,采用全自动大功率、大光斑激光熔覆设备,通过激光熔覆,可控制薄壁件熔覆变形量,减小后序加工余量,提高加工效率；将轴承内圈的工艺流程固化后,可使产品质量的稳定性、使用寿命和装备作战时间大幅度提高。(A method for producing inner rings of front and rear ring bearings is used for new process application, production and solidification of new materials of the front and rear ring bearings. The bearing inner ring is formed by precision investment casting of an alloy steel base material, precision investment casting is carried out, a bearing channel is formed by laser deposition of a nano alloy powder material, after numerical control turning and milling composite center machining and numerical control forming grinding, the whole bearing is treated by black zinc plating, and a salt spray test needs to reach 200 hours. The precision investment casting process is adopted, so that the dimensional precision and the surface roughness of the bearing inner ring and the material utilization rate can be effectively improved; the deposition of the bearing channel adopts the alloy nano powder with high mechanical property, high wear resistance and corrosion resistance, adopts full-automatic high-power and large-spot laser deposition equipment, and can control the deposition deformation of the thin-walled workpiece through laser deposition, reduce the subsequent machining allowance and improve the machining efficiency; after the process flow of the bearing inner ring is solidified, the stability of the product quality, the service life and the equipment fighting time can be greatly improved.)
1. A production method of a front ring bearing inner ring and a rear ring bearing inner ring is characterized in that: the bearing inner ring is formed by precision investment casting of an alloy steel base material, precision investment casting is carried out, a bearing channel is formed by laser deposition of a nano alloy powder material, after numerical control turning and milling composite center machining and numerical control forming grinding, the whole bearing is treated by black zinc plating, and a salt spray test needs to reach 200 hours.
2. The method for producing inner races of front and rear ring bearings according to claim 1, wherein: the alloy steel base material for precision investment casting of the bearing inner ring is ZG32MnMo, and comprises the following components: 0.27-0.35 percent of C, 0.2-0.8 percent of Si, 0.9-1.2 percent of Mn, 0.20-0.30 percent of Mo, and less than or equal to 0.03 percent of P and S; the mechanical properties are as follows: the upper yield strength ReH is more than or equal to 392MPa, the tensile strength Rm is more than or equal to 686MPa, the elongation percentage A% after fracture is more than or equal to 15%, the reduction of area Z% is more than or equal to 30%, the impact absorption power Aku1 is more than or equal to 27, and the hardness is more than or equal to HB 217.
3. The method for producing inner races of front and rear ring bearings according to claim 1, wherein: the investment precision casting comprises the procedures of aluminum mould manufacturing, wax mould manufacturing, shell mould manufacturing and subsequent drying, roasting, pouring and solidifying; the manufacturing of the aluminum mould adopts a leaning and joining process to improve the deformation of the collapsed side of a casting finished product, adopts chamfer smooth transition to reduce stress concentration, adopts small holes with the diameter of 6 mm-8 m at the thicker part to reduce shrinkage cavity and sand hole of the casting finished product, adopts a shaping tool to correct the casting finished product after forming, and finally adopts shot blasting treatment to improve the surface roughness of the casting finished product; the wax mold is manufactured by adopting K512 wax material with extremely high dimensional precision, stable linear shrinkage rate and good surface smoothness of a casting, and the wax mold is formed by an aluminum mould and a die-casting production line; the shell mold manufacturing and forming process adopts mold release agent to degrease the wax mold, and the surface of the wax mold is dipped with refractory coating which is made of high-alumina refractory material AL2O3More than or equal to 50 percent, scattering bottom sand outside the wax pattern coating, using zircon powder and zircon sand, using mullite sand and mullite powder for a surface layer, and ensuring the fire resistance to be more than 1750 ℃; naturally drying the shell before hardening, drying the shell after chemical hardening, soaking the surface of the wax mould with refractory paint and sanding, and chemically hardening, and forming a six-layer shell with the thickness of 8mm after five times of hardening and drying; standing the shell mold for more than 2-4 h for continuous hardening to ensure that the shell mold has enough wet strength, and dewaxing the lost melting mold (dewaxing) by using hot water at 85-95 ℃; roasting the shell after dewaxing, and removing water, residual wax materials and saponified substances in the shell by using a natural gas furnace, wherein the roasting temperature is 850-980 ℃, and the heat preservation time is 0.5-2 h; the casting process comprises the steps of furnace charge preparation, alloy smelting, shell casting, solidification, shelling, piece dropping, gate grinding, cleaning, appearance size detection, furnace cooling at the temperature of 20-30 ℃ for converting annealing heat treatment into austenite, performing shot blasting and sand blasting treatment on the casting to remove residual sand and oxide skin on the surface of the finished casting, mechanically correcting the appearance of the finished casting by using a tool clamp and a hydraulic machine,the method adopts fluorescent magnetic powder inspection to detect surface cracks of the finished casting product and X-ray inspection to detect shrinkage cavity and loosening defects in the finished casting product, and adopts an antirust liquid immersion method for antirust treatment to ensure that the casting product is not rusted in the stock state.
4. The method for producing inner races of front and rear ring bearings according to claim 1, wherein: the bearing channel laser cladding nano alloy powder adopts a pneumatic or hydraulic automatic chuck to clamp an investment precision casting forming casting, the chuck drives the casting to rotate, a laser head is fixed on a chuck mechanical arm, the nano alloy powder and a base material of a bearing inner ring channel are quickly melted by utilizing a high-energy density laser beam through powder feeding of an automatic powder feeder and laser beam heating, so that the nano alloy powder is quickly solidified on the surface of the base material to form an alloy layer with completely different components and performances from the base material; the laser cladding power is 2.5KW, the scanning speed is 21mm/s, the thread pitch of a cladding spiral track is 2.4mm, the inclination angle of a clamping chuck is 5-10 degrees, the inclination angle of a powder feeder nozzle relative to a machining center line is 45 degrees, the thickness of a cladding layer is 0.5mm, the total thickness of the cladding layer is 1.2-1.3mm, the thickness of the cladding layer is required to be uniform, the unevenness is less than or equal to 0.2, and the uniformity, no pores and no cracks of the structure performance and the hardness HRC51-56 on the surface of a bearing channel are ensured.
5. The method for producing inner races of front and rear ring bearings according to claim 1, wherein: the numerical control turning and milling combined center processing of the bearing inner ring is to clamp a casting at one time on one device in a turning and milling mode, so that the outer diameter, the inner diameter and the end face of the casting are achieved, and a step face, a drilling hole and a reaming hole are milled.
6. The method for producing inner races of front and rear ring bearings according to claim 1, wherein: the numerical control forming and grinding of the bearing inner ring is to form a casting by using a diamond pen to trim a grinding wheel, electromagnetically and centerless clamp a fixed plane, position the outer diameter of a floating supporting block, position at one time and sequentially grind and form two channels.
7. The method for producing inner races of front and rear ring bearings according to claim 1, wherein: the black zinc plating treatment process of the bearing inner ring comprises the following steps:
(a) stress relief: tempering treatment is carried out before black zinc plating, the tempering furnace is heated to 140 +/-10 ℃, and the temperature is kept for 5 hours to eliminate the bearing
Stress of the inner ring;
(b) alkali liquor deoiling: the bearing inner ring is cleaned by alkali liquor, the alkali liquor has no influence on the coating binding force of the bearing inner ring, grease and slight rust on the surface of the bearing inner ring are removed mainly by means of the chemical action (saponification action) of alkali, and the coated surface is enabled to be slightly rusted
Purifying;
(c) acid washing and activating: pickling with hydrochloric acid to remove rust and oxide film on the surface of the bearing inner ring and to make the surface in an activated state;
(d) black zinc plating: adopting a zincate galvanizing process and using ZN-265 additive to obtain a plating layer more than or equal to 8 um;
(e) a light emitting procedure: soaking the bearing inner ring in 40-60 g/L nitric acid solution at room temperature for 3-10 s, and performing bright dipping treatment on the black zinc plated bearing inner ring to improve the brightness of a coating of the bearing inner ring;
(f) black passivation procedure: passivating for 30-120 s to form a layer of chromate passivation film with fine structure and corrosion resistance which can be improved by 7-10 times on the surface of the galvanized layer;
(g) rinsing: performing multi-stage dynamic countercurrent rinsing to remove stains on the surface of the bearing inner ring;
(h) a drying procedure: the hot water washing temperature before drying is not more than 60 ℃, then the mixture is put into a dryer, the temperature is 50-60 ℃, and the temperature is kept for 30 min;
(i) a dehydrogenation step: and after drying, putting the bearing inner ring into a drying box, and removing hydrogen at the temperature of 140 +/-10 ℃ for more than or equal to 5h to reduce the hydrogen brittleness of the bearing inner ring.
Technical Field
The invention relates to the technical field of bearing manufacturing, in particular to a novel process application and a production curing method of a front ring bearing and a rear ring bearing.
Background
The front ring bearing and the rear ring bearing are used for automatically conveying guide rail bearings of the artillery unit, and can realize the functions of steering, translation, bearing and the like, so that the armored vehicle can realize automation, unmanned operation and the like during shooting.
The front ring bearing and the rear ring bearing comprise a transmission front ring and a transmission rear ring, and are respectively composed of an inner ring, an outer ring and a rolling body of the front ring and the rear ring, wherein the rolling body is a standard purchased part, the outer ring is a simple thin-wall ring part, the production operation efficiency is very high, but the inner ring structures of the front ring and the rear ring are special and complex, and a lot of problems exist in the production process and mainly exist as follows:
(1) inner ring material problem: the inner ring material is forged by low-carbon alloy steel, and the blank formability of a forged piece is poor, so that the subsequent machining difficulty and the machining amount are very large, the weight of the blank exceeds 9kg, the weight of a finally machined part is 1.8kg, the material utilization rate is only 20%, and the machining working hour exceeds 40 hours.
(2) The welding problem of the inner ring raceway is as follows: because the inner ring simultaneously bears support and rolling, the bearing raceway is designed as same as the bearing raceway, a layer of material with higher carbon content needs to be welded on the low-carbon alloy steel as the material of the inner ring and is quenched, the welding adopts a build-up welding process, the build-up welding has large heat productivity and long time, so the fusion temperature is quickly raised, the deformation of the inner ring is serious, the yield is very low, the rejection rate can be reduced only by adopting a method of increasing the structural weight of a part blank, but the consequences that the subsequent working procedure has large processing amount and the processing quality is difficult to ensure are caused in turn.
(3) The production process of the inner rings of the front ring and the rear ring adopts the traditional process layout and production organization mode at present, but the material transfer, the process connection and the processing information are still manually operated and recorded, the processing equipment still adopts single-person single-machine operation, the production efficiency is very low, the process quality is unstable, the capacity is less than about 20 parts (640 sets) per month, and the requirement of the modern industrial development can not be met far.
(4) The existing investment casting technology has various defects: the liquid metal is not filled in the cavity, so that the meat deficiency and cold shut of the casting are caused, gaps, depressions, scabs and toad skins (orange peels) which are not completely fused are formed on the casting, a plurality of uneven bulges are formed on the surface of the casting, the inner surface and the outer surface of the casting are locally swelled to form irregular bulges, a plurality of scattered or dense small spurs and iron spurs (cucumber spurs) appear on the surface of the casting, and redundant smooth metal particle iron beans are arranged at the grooves or the corners of the casting.
(5) The existing electrogalvanizing technology has the defects that: the bubbling, the peeling and the coating fluffing are easy to occur, mainly because the part is not thoroughly treated before plating, has impurities such as oil stain and the like, the current is too large, or the bath solution has impurities, or the content of certain medicine in the passivation bath is too low. The white zinc plating salt spray test is generally carried out for 24 hours, and the color zinc plating salt spray test is carried out for 72 hours.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for producing inner rings of front and rear ring bearings so as to shorten the production period of the inner rings of the front and rear ring bearings and prolong the service life of the inner rings of the front and rear ring bearings.
In order to achieve the purpose, the bearing inner ring is formed by precision investment casting of an alloy steel base material, laser deposition of a nano alloy powder material is adopted in a bearing channel, black zinc plating treatment is adopted integrally after numerical control turning and milling composite center machining and numerical control forming grinding, and a salt spray test needs to be carried out for 200 hours.
The alloy steel base material for precision investment casting of the bearing inner ring is ZG32MnMo, and comprises the following components: 0.27-0.35 percent of C, 0.2-0.8 percent of Si, 0.9-1.2 percent of Mn, 0.20-0.30 percent of Mo, and less than or equal to 0.03 percent of P and S; the mechanical properties are as follows: the upper yield strength ReH is more than or equal to 392MPa, the tensile strength Rm is more than or equal to 686MPa, the elongation percentage A% after fracture is more than or equal to 15%, the reduction of area Z% is more than or equal to 30%, the impact absorption power Aku1 is more than or equal to 27, and the hardness is more than or equal to HB 217.
The investment precision casting comprises the procedures of aluminum mould manufacturing, wax mould manufacturing, shell mould manufacturing and subsequent drying, roasting, pouring and solidifying; the manufacturing of the aluminum mould adopts a leaning and joining process to improve the deformation of the collapsed side of a casting finished product, adopts chamfer smooth transition to reduce stress concentration, adopts small holes with the diameter of 6 mm-8 m at the thicker part to reduce shrinkage cavity and sand hole of the casting finished product, adopts a shaping tool to correct the casting finished product after forming, and finally adopts shot blasting treatment to improve the surface roughness of the casting finished product; the wax mold is manufactured by adopting K512 wax material with extremely high dimensional precision, stable linear shrinkage rate and good surface smoothness of a casting, and the wax mold is formed by an aluminum mould and a die-casting production line; the shell mold manufacturing and forming process adopts mold release agent to degrease the wax mold, and the surface of the wax mold is dipped with refractory coating which is made of high-alumina refractory material AL2O3More than or equal to 50 percent, scattering bottom sand outside the wax pattern coating, using zircon powder and zircon sand, using mullite sand and mullite powder for a surface layer, and ensuring the fire resistance to be more than 1750 ℃; naturally drying the shell before hardening, drying the shell after chemical hardening, soaking the surface of the wax mould with refractory paint and sanding, and chemically hardening, and forming a six-layer shell with the thickness of 8mm after five times of hardening and drying; standing the shell mold for more than 2-4 h for continuous hardening to ensure that the shell mold has enough wet strength, and dewaxing the lost melting mold (dewaxing) by using hot water at 85-95 ℃; roasting the shell after dewaxing, and removing water, residual wax materials and saponified substances in the shell by using a natural gas furnace, wherein the roasting temperature is 850-980 ℃, and the heat preservation time is 0.5-2 h; the casting process comprises the steps of furnace charge preparation, alloy smelting, shell casting, solidification, shelling, piece dropping, gate grinding, cleaning and appearance size detection, furnace cooling at the temperature of 20-30 ℃ for converting annealing heat treatment into austenite, performing shot blasting and sand blasting treatment on the casting to remove residual sand and oxide skin on the surface of the finished casting product, mechanically correcting the appearance of the finished casting product by using a tool clamp and a hydraulic machine, detecting cracks on the surface of the finished casting product by using fluorescent magnetic powder flaw detection, detecting shrinkage and loosening defects in the finished casting product by using X-ray flaw detection, and performing rust prevention treatment by using an antirust liquid immersion method to ensure that the stock state of the casting product is not rusted.
The bearing channel laser cladding nano alloy powder adopts a pneumatic or hydraulic automatic chuck to clamp an investment precision casting forming casting, the chuck drives the casting to rotate, a laser head is fixed on a chuck mechanical arm, the nano alloy powder and a base material of a bearing inner ring channel are quickly melted by utilizing a high-energy density laser beam through powder feeding of an automatic powder feeder and laser beam heating, so that the nano alloy powder is quickly solidified on the surface of the base material to form an alloy layer with completely different components and performances from the base material; the laser cladding power is 2.5KW, the scanning speed is 21mm/s, the thread pitch of a cladding spiral track is 2.4mm, the inclination angle of a clamping chuck is 5-10 degrees, the inclination angle of a powder feeder nozzle relative to a machining center line is 45 degrees, the thickness of a cladding layer is 0.5mm, the total thickness of the cladding layer is 1.2-1.3mm, the thickness of the cladding layer is required to be uniform, the unevenness is less than or equal to 0.2, and the uniformity, no pores and no cracks of the structure performance and the hardness HRC51-56 on the surface of a bearing channel are ensured.
The numerical control turning and milling combined center processing of the bearing inner ring is to clamp a casting at one time on one device in a turning and milling mode, so that the outer diameter, the inner diameter and the end face of the casting are achieved, and a step face, a drilling hole and a reaming hole are milled.
The numerical control forming and grinding of the bearing inner ring is to form a casting by using a diamond pen to trim a grinding wheel, electromagnetically and centerless clamp a fixed plane, position the outer diameter of a floating supporting block, position at one time and sequentially grind and form two channels.
The black zinc plating treatment process of the bearing inner ring comprises the following steps:
(a) stress relief: tempering treatment is carried out before black zinc plating, the tempering furnace is heated to 140 +/-10 ℃, and the temperature is kept for 5 hours to eliminate the bearing
Stress of the inner ring;
(b) alkali liquor deoiling: the bearing inner ring is cleaned by alkali liquor, the alkali liquor has no influence on the coating binding force of the bearing inner ring, grease and slight rust on the surface of the bearing inner ring are removed mainly by means of the chemical action (saponification action) of alkali, and the coated surface is enabled to be slightly rusted
Purifying;
(c) acid washing and activating: pickling with hydrochloric acid to remove rust and oxide film on the surface of the bearing inner ring and to make the surface in an activated state;
(d) black zinc plating: adopting a zincate galvanizing process and using ZN-265 additive to obtain a plating layer more than or equal to 8 um;
(e) a light emitting procedure: soaking the bearing inner ring in 40-60 g/L nitric acid solution at room temperature for 3-10 s, and performing bright dipping treatment on the black zinc plated bearing inner ring to improve the brightness of a coating of the bearing inner ring;
(f) black passivation procedure: passivating for 30-120 s to form a layer of chromate passivation film with fine structure and corrosion resistance which can be improved by 7-10 times on the surface of the galvanized layer;
(g) rinsing: performing multi-stage dynamic countercurrent rinsing to remove stains on the surface of the bearing inner ring;
(h) a drying procedure: the hot water washing temperature before drying is not more than 60 ℃, then the mixture is put into a dryer, the temperature is 50-60 ℃, and the temperature is kept for 30 min;
(i) a dehydrogenation step: and after drying, putting the bearing inner ring into a drying box, and removing hydrogen at the temperature of 140 +/-10 ℃ for more than or equal to 5h to reduce the hydrogen brittleness of the bearing inner ring.
Compared with the prior art, the invention has the following advantages:
(1) by adopting a precise investment casting process, the dimensional precision and the surface roughness of the bearing inner ring and the material utilization rate can be effectively improved.
(2) The bearing channel is deposited by using the alloy nano powder with high mechanical property, high wear resistance and corrosion resistance, full-automatic high-power large-spot laser cladding equipment is adopted, and the cladding deformation of the thin-walled workpiece can be controlled by laser cladding, so that the subsequent machining allowance is reduced, and the machining efficiency is improved.
(3) After the process flow of the bearing inner ring is solidified, the stability of the product quality, the service life and the equipment operation time can be greatly improved, so that the maintenance time and the cost are reduced, the surface roughness of a casting is improved, the deformation of the product is controlled to be less than or equal to 0.05, and the material cost and the processing cost are reduced by about 60 percent.
Detailed Description
The invention adopts investment precision casting alloy steel base material to be formed by investment precision casting so as to obtain a casting with higher dimensional precision and surface finish, the bearing channel adopts laser deposited nano alloy powder material, after numerical control turning and milling composite center processing and numerical control forming grinding, the whole body adopts black zinc plating treatment, and the salt spray test needs 200 hours to improve the long-term corrosion resistance in the bearing.
The alloy steel base material for precision investment casting of the bearing inner ring is ZG32MnMo, and comprises the following components: 0.27-0.35 percent of C, 0.2-0.8 percent of Si, 0.9-1.2 percent of Mn, 0.20-0.30 percent of Mo, and less than or equal to 0.03 percent of P and S; the mechanical properties are as follows: the upper yield strength ReH is more than or equal to 392MPa, the tensile strength Rm is more than or equal to 686MPa, the elongation percentage A% after fracture is more than or equal to 15%, the reduction of area Z% is more than or equal to 30%, the impact absorption power Aku1 is more than or equal to 27, and the hardness is more than or equal to HB 217.
The investment precision casting comprises the procedures of aluminum mould manufacturing, wax mould manufacturing, shell mould manufacturing and subsequent drying, roasting, pouring and solidifying; the manufacturing of the aluminum mould adopts a leaning and joining process to improve the deformation of the collapsed side of a casting finished product, adopts chamfer smooth transition to reduce stress concentration, adopts small holes with the diameter of 6 mm-8 m at the thicker part to reduce shrinkage cavity and sand hole of the casting finished product, adopts a shaping tool to correct the casting finished product after forming, and finally adopts shot blasting treatment to improve the surface roughness of the casting finished product; the wax mold is manufactured by adopting K512 wax material with extremely high dimensional precision, stable linear shrinkage rate and good surface smoothness of a casting, and the wax mold is formed by an aluminum mould and a die-casting production line; the shell mold manufacturing and forming process adopts mold release agent to degrease the wax mold, and the surface of the wax mold is dipped with refractory coating which is made of high-alumina refractory material AL2O3More than or equal to 50 percent, scattering bottom sand outside the wax pattern coating, using zircon powder and zircon sand, using mullite sand and mullite powder for a surface layer, and ensuring the fire resistance to be more than 1750 ℃; naturally drying the shell before hardening, drying the shell after chemical hardening, soaking the surface of the wax mould with refractory paint and sanding, and chemically hardening, and forming a six-layer shell with the thickness of 8mm after five times of hardening and drying; standing the shell mold for more than 2-4 h for continuous hardening to ensure that the shell mold has enough wet strength, and dewaxing the lost melting mold (dewaxing) by using hot water at 85-95 ℃; roasting the shell after dewaxing, and removing water, residual wax materials and saponified substances in the shell by using a natural gas furnace, wherein the roasting temperature is 850-980 ℃, and the heat preservation time is 0.5-2 h; the casting process comprises the steps of furnace charge preparation, alloy smelting, shell casting, solidification, shelling, piece falling, gate grinding, cleaning, appearance size detection and annealing heat treatmentThe temperature of the austenite is changed into + 20-30 ℃, furnace cooling is carried out, shot blasting and sand blasting are carried out on the casting to remove residual sand and oxide skin on the surface of the finished casting, a tool clamp and a hydraulic machine are adopted to mechanically correct the appearance of the finished casting, fluorescent magnetic powder flaw detection is adopted to detect cracks on the surface of the finished casting, X-ray flaw detection is adopted to detect shrinkage cavity and loose defects in the finished casting, and an antirust liquid immersion method is adopted for antirust treatment to ensure that the inventory state of the casting is not rusted.
The bearing channel laser cladding nano alloy powder adopts a pneumatic or hydraulic automatic chuck to clamp an investment precision casting forming casting, the chuck drives the casting to rotate, a laser head is fixed on a chuck mechanical arm, the nano alloy powder and a base material of a bearing inner ring channel are quickly melted by utilizing a high-energy density laser beam through powder feeding of an automatic powder feeder and laser beam heating, so that the nano alloy powder is quickly solidified on the surface of the base material to form an alloy layer with completely different components and performances from the base material; the laser cladding power is 2.5KW, the scanning speed is 21mm/s, the thread pitch of a cladding spiral track is 2.4mm, the inclination angle of a clamping chuck is 5-10 degrees, the inclination angle of a powder feeder nozzle relative to a machining center line is 45 degrees, the thickness of a cladding layer is 0.5mm, the total thickness of the cladding layer is 1.2-1.3mm, the thickness of the cladding layer is required to be uniform, the unevenness is less than or equal to 0.2, and the uniformity, no pores and no cracks of the structure performance and the hardness HRC51-56 on the surface of a bearing channel are ensured.
The numerical control turning and milling combined center processing of the bearing inner ring is to clamp a casting at one time on one device in a turning and milling mode, so that the outer diameter, the inner diameter and the end face of the casting are achieved, and a step face, a drilling hole and a reaming hole are milled. The numerical control forming and grinding of the bearing inner ring is to form a casting by using a diamond pen to trim a grinding wheel, electromagnetically and centerless clamp a fixed plane, position the outer diameter of a floating supporting block, position for one time, and sequentially grind and form two channels.
The black zinc plating treatment process of the bearing inner ring comprises the following steps:
(a) stress relief: tempering treatment is carried out before black zinc plating, the tempering furnace is heated to 140 +/-10 ℃, and the temperature is kept for 5 hours to eliminate the bearing
Stress of the inner ring;
(b) alkali liquor deoiling: the bearing inner ring is cleaned by alkali liquor, the alkali liquor has no influence on the coating binding force of the bearing inner ring, grease and slight rust on the surface of the bearing inner ring are removed mainly by means of the chemical action (saponification action) of alkali, and the coated surface is enabled to be slightly rusted
Purifying;
(c) acid washing and activating: pickling with hydrochloric acid to remove rust and oxide film on the surface of the bearing inner ring and to make the surface in an activated state;
(d) black zinc plating: adopting a zincate galvanizing process and using ZN-265 additive to obtain a plating layer more than or equal to 8 um;
(e) a light emitting procedure: soaking the bearing inner ring in 40-60 g/L nitric acid solution at room temperature for 3-10 s, and performing bright dipping treatment on the black zinc plated bearing inner ring to improve the brightness of a coating of the bearing inner ring;
(f) black passivation procedure: passivating for 30-120 s to form a layer of chromate passivation film with fine structure and corrosion resistance which can be improved by 7-10 times on the surface of the galvanized layer;
(g) rinsing: performing multi-stage dynamic countercurrent rinsing to remove stains on the surface of the bearing inner ring;
(h) a drying procedure: the hot water washing temperature before drying is not more than 60 ℃, then the mixture is put into a dryer, the temperature is 50-60 ℃, and the temperature is kept for 30 min;
(i) a dehydrogenation step: and after drying, putting the bearing inner ring into a drying box, and removing hydrogen at the temperature of 140 +/-10 ℃ for more than or equal to 5h to reduce the hydrogen brittleness of the bearing inner ring.