Quenching the surface layer of parts by means of solid-state phase transformation and 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 and high production efficiency; The heating time is short, and the surface oxidation decarburization is very slight.
The importance of Grease in NSK Tapered Roller Bearing Maintenance
The metal surface layer is plastically deformed by mechanical methods 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. Cold blast, blast, blast, blast, etc. The characteristics of these methods are: the strengthening layer dislocation density increases and the sub crystal structure is refined, so as to improve its hardness and strength and reduce the surface roughness value, which can significantly improve the surface fatigue strength of parts and reduce the sensitivity of fatigue notch. The importance of Grease in NSK Tapered Roller Bearing Maintenance
This strengthening method has the advantages of simple process and remarkable effect. There is no obvious boundary between the hardened layer and the matrix, the structure is coherent, and it is not easy to fall off in use. Most of its methods have been applied in the bearing industry:
the surface impact strengthening of rolling element is the application of this kind of method, and precision rolling has become a new ferrule processing and strengthening method.The importance of Grease in NSK Tapered Roller Bearing Maintenance
The evaporation (degree) of fag bearing grease indicates the degree of volatilization of grease oil when the grease is used for a long time under high temperature conditions. The smaller the evaporation, the better. The evaporation of grease mainly depends on the properties and fraction composition of lubricating oil.
Oxidation stability refers to the ability of lubricating grease to resist the action of heat and oxygen and keep its properties from permanent change when it is stored for a long time or used at high temperature for a long time.
Due to oxidation, the content of free alkali is often reduced or the content of free organic acid is increased, the dropping point is reduced, the appearance color is darker, there is a strange odor, the consistency, strength limit and similar viscosity are reduced, and corrosive products and substances that destroy the structure of lubricating grease are generated, resulting in the separation of soap and oil.
Therefore, in the long-term storage of lubricating grease, it should be stored in a dry and ventilated environment to prevent sunlight exposure, and the changes of free alkali or free organic acid, corrosivity and other items should be checked regularly to ensure its quality and performance.The importance of Grease in NSK Tapered Roller Bearing Maintenance
When checking fag bearings, never expose needle roller one-way bearings to pollutants or moisture. If the work is interrupted, the machine shall be covered with oil paper, plastic sheet or similar materials.The importance of Grease in NSK Tapered Roller Bearing Maintenance
If it is possible to clean the unshaded needle roller one-way bearing without disassembly, clean it with a brush coated with white spirit, and then wipe it dry with a piece of lint free cloth or blow it dry with compressed air (be careful not to let the fag bearing assembly start rotation).
Do not clean the fag bearing with dense cover or dust-proof; Just wipe the outer surface. If the needle roller one-way bearing is damaged, it needs to be replaced.The importance of Grease in NSK Tapered Roller Bearing Maintenance
In order to judge whether the NSK tapered roller bearing disassembled can be used, it is necessary to check after the bearing is cleaned. Check the state of raceway surface, rolling surface and mating surface, the wear condition of persistence frame, the increase of bearing clearance and the damage of irrelevant dimensional accuracy drop, which are abnormal. For non separable small ball bearings, use one hand to check the support of the inner ring and rotate the outer ring to confirm whether it is fluent.The importance of Grease in NSK Tapered Roller Bearing Maintenance
Bearing maintenance: bearing cleaning: when disassembling the lower NSK tapered roller bearing for maintenance, first record the appearance of the bearing, confirm the residual amount of smoothing agent, and wash the bearing after sampling the smoothing agent used for inspection. As a cleaning agent, gasoline and kerosene are commonly used.
Outside the bearing industry, the use of this kind of grease is large, and the bearings of high-speed wire rod mill account for about 70% of the total grease.
Because that kind of grease uses the lithium white with soft fiber and light and difficult to filter as the thickener, and uses mineral oil as the basic oil, it is difficult to know the requirements of low-grade bearings outside the feet to reduce the vibration value. Another benefit is that it has good pumping performance. As a cleaning agent, gasoline and kerosene are commonly used.
Whether it is mechanical fatliquoring or manual fatliquoring, it is simple and difficult to do. Moreover, the grease is cheap and can greatly reduce the cost of NSK tapered roller bearings. However, due to the use of mineral basic oil, this kind of grease is making great achievements in some physical and chemical objectives other than rust removal and rust prevention.
If the bearing life can only reach 200 hours, the linear guide rail is a common problem. There is no problem when the starting and running torque is tested at – 20 ℃. The service temperature of this kind of grease is generally – 20 ~ 120 ℃.
When it is used at a high temperature above 150 ℃, the phenomenon of rapid evaporation and severe flow of basic oil will appear, which will greatly shorten the service life of the bearing.The importance of Grease in NSK Tapered Roller Bearing Maintenance
1. The oil bath of the bearing is smooth
Oil bath smoothing is a common smoothing method in bearings, which is suitable for the smoothing of low and medium speed bearings. The NSK tapered roller bearing is partially immersed in the groove, and the smooth oil is brought up by the rotating bearing parts, and then flows back to the oil groove. The oil level should be slightly lower than the center of the low rolling element.
2. The oil dripping of the bearing is smooth
Smooth oil dripping is suitable for NSK tapered roller bearing parts requiring quantitative supply of smooth oil. The amount of oil dripping should be one drop every 3-8 seconds. Excessive oil will increase the bearing temperature.
3. The circulating oil of the bearing is smooth
Use the oil pump to deliver the filtered oil to the bearing parts. The smooth oil after passing through NSK tapered roller bearings is filtered and cooled before use. Because the circulating oil can take away certain heat and cool the bearing, this method is actually used for bearing parts with high speed.
4. spray smoothness of bearings
Oil mist is generated by mixing the dry shrinkage air with the smooth oil through the sprayer, and the airflow can effectively cool the bearing and avoid impurity invasion in the radial bearing. This method is suitable for the smoothing of high-speed and low-temperature bearing parts.
5. The radial of the bearing is smooth
Use the oil pump to inject the low-pressure oil into the NSK tapered roller bearing through the nozzle, and the oil injected into the bearing flows into the oil groove through the other end of the bearing. When the bearing rotates at a high speed, the rolling element and the maintenance frame also cause air flow around at a relatively high rotation speed.
It is difficult to send the smooth oil to the bearing in an individual smooth way. At this time, the smooth oil must be sprayed into the bearing in the way of low-pressure radiation, and the position of the nozzle should be placed between the inner ring and the center of the maintenance frame.