Ultra-thin and ultra-fine grain size phosphating process for bearing ring

Abstract

The invention relates to a phosphating technology, in particular to an ultra-thin and ultra-fine grain size phosphating process for a bearing ring, which comprises the following steps: degreasing and cleaning; rinsing with hot water for the first time; rinsing with hot water for the second time; carrying out phosphating treatment; performing ultrasonic water rinsing; coating oil; and inspecting the parts. Wherein the acidity of the bearing ring phosphating solution is as follows: the total acidity is 45-70, the free acidity is 7-12, and the acid ratio is 5.5-7.0. In addition, in order to optimize the phosphating performance of the product, the phosphating temperature and time of the bearing ring are adjusted. According to the invention, the grain size of phosphating crystals can be refined, so that a phosphating film is more compact and complete, the adhesive capacity is higher, and the binding force and the corrosion resistance are stronger; the thickness of the phosphating film is reduced and is adjusted to 1-3 microns from original 6 microns; the influence of phosphorization on the surface roughness of the bearing ring raceway and the large flange is improved, and the surface contour characteristics of the bearing ring raceway are not influenced. The phosphating process provided by the invention is simple and scientific in process flow and convenient for automatic production, and the phosphating quality and the production efficiency are greatly improved.

Description

Technical Field

[0001] The present invention relates to phosphating technology, and specifically to an ultra-thin and ultra-fine grain size phosphating process for bearing rings. Background Art

[0002] Phosphating treatment refers to a surface chemical treatment method in which the metal surface comes into contact with an acidic solution containing dihydrogen phosphate, undergoes a chemical reaction, and forms a stable insoluble inorganic compound film layer on the metal surface. The formed film is called a phosphating film. The phosphating treatment process for bearing rings is an anti-corrosion technology in which the bearing rings undergo a chemical reaction in a phosphating solution at a certain temperature to form a phosphating film with high adhesion, density, integrity, bonding force, and corrosion resistance, thereby reducing the frictional wear between the inner and outer rings and the rolling elements of the bearing during operation, reducing the corrosion of the inner and outer rings of the bearing caused by the external environment, and improving the service life of the bearing.

[0003] The level of the total acidity of the phosphating solution determines the reaction rate of phosphating film formation and the quality of the film; increasing the total acidity can accelerate the deposition rate of the phosphating film, making the phosphating film layer thin and dense; however, when the total acidity is too high, a powdery ash hanging phenomenon will occur on the surface of the phosphating film; when the total acidity is low, it will affect the deposition rate and corrosion resistance of phosphating film formation; when the free acidity is too high, the formation of the phosphating film will be slow, the film layer crystals will be thick, loose, and the corrosion resistance will be low; when the free acidity is too low, the obtained phosphating film will be very thin, or even no phosphating film can be obtained. The acid ratio is the ratio of the total acidity to the free acidity. The larger the acid ratio, the thicker the phosphating film and the coarser the crystals; the smaller the acid ratio, the thinner the phosphating film and the finer the crystals, but the precipitation increases.

[0004] With the development of technology, the requirements for product precision are getting higher and higher. In the original phosphating process, the total acidity and free acidity of the used phosphating solution are relatively high, resulting in a powdery ash hanging phenomenon on the surface of the phosphating film, and also resulting in a thick, loose, and reduced corrosion resistance of the formed phosphating film layer. Compared with the current technical requirements, the product surface is relatively rough and the adhesion of the phosphating layer is poor. When the phosphating film on the raceway surface falls off, the roughness value of the raceway surface increases, and at the same time, it will also damage the contour shape of the raceway, change the contact state between the raceway and the roller, make the bearing operation force unbalanced, increase friction, generate heat, and cause hot axle faults. In addition, a large amount of falling phosphating film causes lubricating grease pollution, reducing its lubricating performance and also exacerbating the occurrence of hot axle faults. Summary of the Invention

[0005] Aiming at the problems existing in the background art, the purpose of the present invention is to propose an ultra-thin and ultra-fine grain size phosphating process for bearing rings, the process flow of which is simple and scientific, can effectively improve the phosphating quality and production efficiency, and is convenient for automated production.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: A phosphating process for ultra-thin and ultra-fine grain size of a bearing ring comprises the following steps: Step S1, degreasing and cleaning to remove oil stains on the surface of the bearing ring; Step S2, first hot water rinsing; using circulating tap water, the temperature is 68°C~87°C, and the time is 1.5min~3.5min; Step S3, second hot water rinsing; using circulating tap water, the temperature is 78°C ~ 92°C, the time is 1.5min ~ 3.5min; Step S4, phosphating treatment; the phosphating bath temperature is 93°C to 100°C, the total phosphating acidity is 45 to 70 points, the free acidity is 7 to 12 points, and the acid ratio is 5.5 to 7.0; the phosphating time is 160s to 320s; Step S5, ultrasonic water rinsing; Step S6, oiling: oiling all surfaces of the parts; Step S7: parts inspection.

[0007] In step S1, the degreasing cleaning temperature is 30° C. to 42° C., the effective content of the metal cleaning agent is 1.3% to 3.2%, and the time is 1.5 min to 3.5 min.

[0008] In step S4, the mass proportion of the phosphating solution is: 2-8 parts of phosphoric acid, 1-10 parts of Marif salt, 2-8 parts of sodium nitrate, 0.5-5 parts of zinc nitrate, 3-5 parts of nickel nitrate, 1-4 parts of sodium nitrite, 0.5-6 parts of hydrogen peroxide, and 45-60 parts of softened water.

[0009] In step S4, the total acidity of the phosphating solution is 57 points, the free acidity is 9 points, and the acid ratio is 6.2.

[0010] In step S5, the ultrasonic water rinsing uses circulating tap water with a temperature of 38° C. to 62° C. and a time of 1.5 min to 3.5 min.

[0011] Beneficial effects of the present invention: 1) Compared with the traditional phosphating solution, the total acidity and free acidity of the phosphating solution are reduced, making the ratio of the phosphating solution more scientific. After the phosphating solution is improved, the phosphating quality is significantly improved, the phosphating film is denser and more complete, the adhesion ability is higher, the bonding force and corrosion resistance are stronger; after phosphating, the surface roughness of the bearing ring raceway and the large rib is no more than 0.5 microns, the surface is fine, and the phosphating film thickness can reach 1~3 microns, which meets the operation requirements of the bearing.

[0012] 2) The present invention controls the temperature of the phosphating solution before and during phosphating, thereby avoiding the problem of reduced phosphating speed and low phosphating quality due to the decrease in temperature of the phosphating solution as the processing time goes by.

[0013] 3) The phosphating process flow of the inner and outer rings of the bearing provided by the present invention adds more cleaning steps compared with other traditional processes, avoiding the problems that part of the surface cannot form a film or the film forming quality is not high due to fingerprints and oil stains. Moreover, it is simpler and more scientific, can be combined with an automated processing line to achieve large-scale production on an assembly line, improve production efficiency, reduce the workload of operators, and lower labor and material costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a flowchart of the present invention.

[0015] Figure 2 is the phosphating film observed under a microscope magnified 500 times of the phosphating product obtained by the original process.

[0016] Figure 3 is the phosphating film observed under a microscope magnified 500 times of the phosphating product obtained in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The present invention will be further described in detail below with reference to the accompanying drawings of the specification and specific embodiments.

[0018] The total acidity and free acidity of the phosphating solution used in the original phosphating process are relatively high, resulting in powdery ash hanging on the surface of the phosphating film, and the formed phosphating film layer is thick, loose, and the corrosion resistance is reduced, greatly affecting the quality of the phosphating film after film formation. The original phosphating process parameters are shown in Table 1.

[0019] Table 1:

[0020] The present invention provides an ultra-thin and ultra-fine grain size phosphating process for bearing rings, wherein the mass ratio of the phosphating solution is: phosphoric acid 2 - 8, Mazu salt 1 - 10, sodium nitrate 2 - 8, zinc nitrate 0.5 - 5, nickel nitrate 3 - 5, sodium nitrite 1 - 4, hydrogen peroxide 0.5 - 6, softened water 45 - 60; the acidity of the phosphating solution for bearing rings is: the total acidity is 45 - 70 points, the free acidity is 7 - 12 points, and the acid ratio is 5.5 - 7.0, which is lower than the total acidity and free acidity of the traditional phosphating solution. The phosphating process parameters of the present invention are shown in Table 2.

[0021] Table 2:

[0022] As Figure 1 shown, an ultra-thin and ultra-fine grain size phosphating process for bearing rings provided by the present invention includes the following steps: Step S1, degreasing and cleaning to remove the oil stains on the surface of the bearing ring; Step S2, the first hot water rinse; using circulating tap water, with a temperature of 68°C to 87°C and a time of 1.5 min to 3.5 min; Step S3, the second hot water rinse; using circulating tap water, with a temperature of 78°C to 92°C and a time of 1.5 min to 3.5 min; Step S4, phosphating treatment; the temperature of the phosphating bath is 93°C to 100°C, and the phosphating time is 160 s to 320 s; Step S5, ultrasonic water rinse; Step S6, oil coating; all surfaces of the parts are coated with oil; Step S7, part inspection.

[0023] In the said Step S1, the temperature of the degreasing and cleaning is 30°C to 42°C, the effective content of the metal cleaning agent (weak alkaline degreasing agent) is 1.3% to 3.2%, and the time is 1.5 min to 3.5 min.

[0024] In the said Step S5, the ultrasonic water rinse uses circulating tap water, with a temperature of 38°C to 62°C and a time of 1.5 min to 3.5 min. Example 1:

[0025] The total acidity of the phosphating solution used in the example is 57 points, the free acidity is 9 points, and the acid ratio is 6.2.

[0026] The specific implementation steps are as follows: Place the inner and outer rings of the bearing to be phosphated on the phosphating rack in a point - contact or line - contact manner. The surface of the ring should be free of obvious oil stains and rust. Then place the parts in a metal cleaning agent with a temperature of 35°C and an effective content of 2.5% for degreasing and cleaning; after degreasing and cleaning, place them in circulating hot tap water at 80°C and 85°C respectively for rinsing for 2.5 minutes. Detect that the temperature of the phosphating bath is 98°C, and then place the bearing rings in the phosphating bath at 98°C for phosphating for 4 minutes; after phosphating is completed, place the bearing rings in circulating tap water at 50°C for ultrasonic cleaning for 2.5 minutes; after cleaning, fully coat the surface of the parts with oil, and then conduct an inspection of the phosphating quality.

[0027] According to the improved phosphating process, through the phosphating treatment of multiple batches of rings, it can be proved that the present invention can make the phosphating crystal grains finer, the phosphating film more dense and complete, with higher adhesion ability, stronger bonding force and corrosion resistance. At the same time, the thickness of the phosphating film becomes thinner, adjusted from the original 6 microns to 1 - 3 microns; it improves the influence of phosphating on the surface roughness of the raceway and large flanges of the bearing rings, reducing the surface roughness Ra from about 1.0 microns caused by the original process to Ra≈0.5 microns; it does not damage the original good profile characteristics of the raceway surface of the rings. The comparison between the phosphating products obtained by the original process and the products obtained by using the process described in the present invention is as Figure 2 、Figure 3 as shown

[0028] In summary, the ultra-thin and ultra-fine grain phosphating process for bearing rings proposed by the present invention is more scientific and more suitable for the phosphating requirements of bearing rings.

[0029] The parts not detailed in the present invention are prior art.

Claims

1. An ultra-thin and ultra-fine grain phosphating process for bearing rings, characterized in that: It includes the following steps: Step S1, degreasing and cleaning to remove the oil stain on the surface of the bearing ring; Step S2, the first hot water rinse; Using circulating tap water, with a temperature of 68°C to 87°C and a time of 1.5 min to 3.5 min; Step S3, the second hot water rinse; using circulating tap water, with a temperature of 78°C to 92°C and a time of 1.5 min to 3.5 min; Step S4, phosphating treatment; the temperature of the phosphating bath is 93°C to 100°C, the total phosphating acidity is 45 to 70 points, the free acidity is 7 to 12 points, and the acid ratio is 5.5 to 7.0; the phosphating time is 160 s to 320 s; Step S5, ultrasonic water rinse; Step S6, oil coating; all surfaces of the parts are coated with oil; Step S7, part inspection.

2. The ultra-thin and ultra-fine grain size phosphating process for a bearing race as claimed in claim 1, wherein: In the said Step S1, the temperature of the degreasing and cleaning is 28°C to 42°C, the effective content of the metal cleaning agent is 1.3% to 3.2%, and the time is 1.5 min to 3.5 min.

3. The ultra-thin and ultra-fine grain size phosphating process for a bearing race as claimed in claim 1, characterized in that: In the said Step S4, the mass fraction ratio range of the phosphating solution is: phosphoric acid 2 to 8, manganese phosphate 1 to 10, sodium nitrate 2 to 8, zinc nitrate 0.5 to 5, nickel nitrate 3 to 5, sodium nitrite 1 to 4, hydrogen peroxide 0.5 to 6, softened water 45 to 60.

4. The ultra-thin and ultra-fine grain size phosphating process for a bearing race as claimed in claim 1, characterized in that: In the said Step S4, the total acidity of the phosphating solution is 57 points, the free acidity is 9 points, and the acid ratio is 6.

2.

5. The ultra-thin and ultra-fine grain phosphating process for a bearing race as claimed in claim 1, characterized in that: In the said Step S5, the ultrasonic water rinse uses circulating tap water, with a temperature of 38°C to 62°C and a time of 1.5 min to 3.5 min.

Images