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How Can the Surface of KOYO Bearing Steel be Strengthened

Source: FAG bearings  Tags: News

The bearing steel used by many bearing companies is not good enough, or even some low-quality bearing steel, which leads to low bearing products. The production enterprises like KOYO bearings are different. The bearing steels used are all of the best quality. . However, we have to tell you how to make KOYO bearing steel surface strengthen.

The working surface and core of bearing parts are quite different in terms of state, structure and performance requirements, and the overall heat treatment often makes it impossible to take into account, and the potential of the material is not fully realized. The application of material surface strengthening technology can not only solve the difference between the structure and requirements of the surface and the core, but also make the surface further obtain some special working performance to meet the working surface of KOYO bearings working under specific conditions. Performance requirements. This is very meaningful in the development of modern science and technology. Traditional surface strengthening methods belong to the category of heat treatment.

The laser, electron beam, ion beam and other surface strengthening methods developed in modern times not only apply some high-tech to the surface strengthening of materials, but also exceed the scope of traditional heat treatment in the process, forming a new technical field. Therefore, the current surface strengthening technology can form a variety of classification methods from different angles, according to the physical and chemical process of surface strengthening technology, it can be roughly divided into five categories: surface deformation strengthening, surface heat treatment strengthening, chemical heat treatment strengthening, surface metallurgy strengthening 3. Surface film reinforcement.   ERIC BEARING LTD can offer  KOYO L68149 / L68110 tapered roller bearings , if you interested , pls click here to learn more : 

1. Chemical heat treatment strengthening

The method of using solid-state diffusion infiltration of an element to change the chemical composition of the metal surface layer to achieve surface strengthening is called chemical heat treatment strengthening, also known as diffusion heat treatment. Including boronizing, metalizing, carburizing and carbonitriding, nitriding and nitrocarburizing, sulfurizing and nitrocarburizing, chromizing, aluminizing and chromium aluminum siliconizing, graphitizing and so on , A wide variety and different characteristics. Infiltrate the element or dissolve into the matrix metal to form a solid solution, or combine with other metal elements to form a compound. In short, the infiltration element can change the chemical composition of the surface layer, and can obtain different phase structures. The treatment process of carburized KOYO bearing steel parts and the surface nitriding strengthening treatment of needle roller KOYO bearing sleeves belong to this kind of strengthening method.

2. Surface deformation strengthening

The metal surface layer is plastically deformed by a mechanical method to form a hardened layer with high hardness and high strength. This surface strengthening method is called surface deformation strengthening, also known as work hardening. Including shot blasting, sand blasting, cold extrusion, rolling, cold rolling and impact, explosion impact strengthening, etc. The characteristics of these methods are: the enhanced layer dislocation density is increased, the subcrystalline structure is refined, so that the hardness and strength are improved, and the surface roughness value is reduced, which can significantly improve the surface fatigue strength of the part and reduce the sensitivity of fatigue notch. This strengthening method has a simple process and a significant effect. There is no obvious boundary between the hardened layer and the substrate, the structure is coherent, and it is not easy to fall off during use. Most of its methods have been applied in the KOYO bearing industry: the surface impact strengthening of rolling elements is the application of this type of method, and precision rolling has become a new method for processing and strengthening ferrules.

3. Surface heat treatment strengthening

The use of solid phase transformation to quench the surface layer of the part by rapid heating is called surface heat treatment, commonly known as surface quenching. Including flame heating quenching, high (medium) frequency induction heating quenching, laser heating or electron beam heating quenching, etc. The characteristics of these methods are: local heating and quenching of the surface, small deformation of the workpiece; fast heating speed, high production efficiency; short heating time, surface oxidation decarburization is very slight. This method is particularly effective in improving the wear resistance and fatigue strength of large and extra large KOYO bearing parts that bear a certain impact load.

4. Surface metallurgy strengthening

The surface strengthening treatment technology that utilizes the remelting and solidification of the metal on the surface of the workpiece to obtain the desired composition or structure is called surface metallurgy strengthening. Including surface auto-dissolving alloy or composite powder coating, surface melting crystallization or amorphous treatment, surface alloying and other methods. It is characterized by rapid heating with high energy density to melt the metal surface layer or the alloying material coated on the metal surface, and then solidify by cooling itself to obtain a special structure or a specific performance strengthening layer. This special structure may be a refined crystal structure, or it may be a supersaturated phase, a metastable phase, or even an amorphous structure, depending on the process parameters and methods of surface metallurgy. Rolling KOYO bearing industry has done laser heating strengthening research on the working surface of micro KOYO bearing, and the effect is good.

5. Surface film reinforcement

Machining process of koyo deep groove ball bearing ring

Although there are many types of deep groove ball bearings, their structural types, tolerance levels, material selection, and processing methods are different, but their basic manufacturing processes include the following:

1. Deep groove ball bearing parts manufacturing-bearing parts inspection-bearing parts demagnetization, cleaning, rust prevention-bearing assembly-deep groove ball bearing finished product inspection-deep groove ball bearing finished demagnetization, cleaning-bearing finished oiled packaging bucket finished product storage .

2. Rings are an important part of deep groove ball bearings. Due to the variety of deep groove ball bearings, the ring size, structure, manufacturing equipment and process methods of different types of deep groove ball bearings are different. And because of the many processing procedures of the ferrule, the complex technology and the high precision requirements, the processing quality of the ferrule has an important impact on the accuracy, service life and performance of the deep groove ball bearing.

3. The raw material for the manufacture of ferrules is cylindrical bar material or tube material. At present, according to different molding processes, deep groove ball bearing ferrules generally have the following manufacturing processes.

(1) (Bar) blanking-forging-annealing (or normalizing-turning (cold roll forming)-heat treatment quenching, tempering-grinding-parts inspection-demagnetization, cleaning-submitting for assembly.

(2) (Bar stock, tube stock) blanking-cold rolling forming-heat treatment quenching, tempering-grinding-parts inspection-demagnetization, cleaning-submitting for assembly.

(3) (Pipe) blanking-turning forming-heat treatment quenching, tempering-grinding-parts inspection-demagnetization, cleaning-submission and assembly

(4) (bar stock) blanking-cold (warm) extrusion molding-turning-heat treatment quenching, tempering-grinding-parts inspection-demagnetization, cleaning-submission and assembly

4. Ferrule forming method: At present, in the processing of ferrules, there are mainly the following forming methods: forging forming, turning forming, cold rolling expansion forming and cold (warm) extrusion forming.

(1) Forging

Through the forging process, the internal defects of the metal can be eliminated, the metal structure can be improved, the metal flow line can be distributed reasonably, and the metal tightness is good. The forging forming process is widely used in the deep groove ball bearing forming process. It can complete the processing from small products with an inner diameter of ~20mm to extra large products with an outer diameter of 5000mm.

(2) Cold roll forming

The cold rolling process is an advanced process method that can improve the material utilization rate, improve the density of the metal structure, and maintain the linearity of the metal flow. It is a chipless processing method. In theory, the cold rolled products can be directly heat-treated and ground without turning. At present, the cold rolling process is mainly used in small and medium-sized deep groove ball deep groove ball bearings. The main process is: forging rough (circular)-turning (excluding groove)-rolling (groove and chamfering) diameter- Softly grind both ends. When using the cold rolling process and the forging process, the accuracy of the product is affected not only by the accuracy of the equipment, but also by the accuracy of the forming mold.

(3) Turning forming:

The traditional turning forming technology in the deep groove ball bearing industry is to use a special lathe and complete the forming process using a centralized process method. However, due to the difficulty of adjusting the equipment used in this method, the low precision of the machine tool, and the low utilization rate of materials, this process method is being eliminated.

The advantages of KOYO bearings and the characteristics of quenched and tempered steel

1. The advantages of KOYO bearings:

(1) Abrasion resistance-because the ceramic material is an inert material, it is more resistant to corrosion and wear;

(2) Long life and wear resistance-the fatigue life of all ceramic KOYO bearings is expected to be 10-50 times longer than that of KOYO bearings. The life of hybrid ceramic KOYO bearings is also about 3-5 times longer than that of KOYO bearings;

(2) High speed and acceleration ability-can be operated under the condition of dn value exceeding 3 million, and slip, wear and heat can be reduced;

(4) High temperature resistance-all ceramic KOYO bearings can be in 500. Working at temperatures above C;

(5) High rigidity-due to the high elastic modulus of ceramic materials, its rigidity is 15-20% greater than ordinary steel KOYO bearings;

(6) Very little lubrication is required-the friction coefficient of ceramic materials is low, and the ceramic KOYO bearings with oil lubrication are used. In the case where the lubricating oil is thinned or lean, the lubricating ability is still not lower than the traditional tradition of steel KOYO bearings. Lubricant

(7) Low torque-According to the structure, the torque of ceramic KOYO bearings is reduced by about 1/3;

2. Characteristics of quenched and tempered steel:

(1) Medium hardenable steel:

The oil quenching of this type of steel is directly from 40 to 60n, m. Commonly used steel types are chromium molybdenum steel and chromium manganese steel. Common grades are 35 (jrMn, 42CrMo, 35L: rMnV, 40CrMn, 35CrMnSi, 30CrMnsi, 35 (: rMnTi, 40crMnTi, 40crNi, etc.), chromium-molybdenum steel has high hardenability, high temperature strength and good structural stability, eliminating the return Fire brittleness and other characteristics, 42CrMo is used to manufacture quenched and tempered parts with high strength and large cross-section, such as gears, turbo-generator main shafts, connecting rods under heavy load, etc., and can also be manufactured below 5 (:) o ℃ Long-term working parts; chromium-manganese steel has high hardenability and strength, and the toughness has not been reduced. 30(: rMnsi is a high-strength steel with good weldability. It is used to manufacture compression plates for high-pressure blowers and high-speed load grinding wheel shafts. And other important parts.

(2) High hardenability steel:

The critical diameter of this type of steel is 60~100 mm. Common material grades are 30Mn2MoW, 40CrMnMo, 30 (: rNi3, 37CrNi3, 40CrNiMc), 45CrNiMov, 25cr2Ni4w, etc. 40crMnMo is a commonly used high hardenability steel, which has the characteristics of low tempering brittleness and small overheating tendency. Large-area, high-strength and high-toughness parts, such as the axles of large heavy-duty vehicles.

(3) Low hardenability steel:

It is generally used to manufacture small and unimportant parts; chromium steel has better hardenability, higher tempering stability than carbon steel, wide quenching temperature, not easy to overheat, and small tendency to deform and crack, so it is widely used; The function of manganese steel is similar to that of chromium steel. Manganese greatly reduces the critical cooling rate of steel and improves the strength and hardness of steel. Boron in boron steel significantly improves the hardenability of the steel, its performance is close to 40Cr, and the critical diameter of oil quenching In the range of 20-30mm, it is often used as automobile half shaft, worm, spline shaft, etc.