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1. Requirements for installation surface and installati […]
1. Requirements for installation surface and installation environment
If foreign materials such as iron filings, burrs, dust, etc. enter the SKF bearing, the SKF bearing will generate noise and vibration during operation, and may even damage the raceway and rolling elements. Therefore, before installing SKF bearings, you must ensure that the installation surface and the installation environment are clean.
2. SKF bearings must be cleaned before installation
SKF bearing surface is coated with anti-rust oil, you must carefully clean with clean gasoline or kerosene, and then apply clean high-quality or high-speed high-temperature lubricating grease before installation and use. The effect of cleanliness on SKF bearing life and vibration noise is very large. But we have to remind you in particular: the fully enclosed SKF bearings do not need to be cleaned and refueled.
3, the choice of grease
Lubrication has a very important effect on the operation and life of SKF bearings. Here is a brief introduction to the general principles of grease selection. Lubricating greases are made of base oil, thickeners and additives. The performance of different types and different types of lubricating greases of the same type is very different. The allowable rotation limits are different. Be careful when choosing. The performance of the grease is mainly determined by the base oil. Generally, low viscosity base oil is suitable for low temperature and high speed, and high viscosity is suitable for high temperature and high load. Thickener is also related to lubricating performance, the water resistance of thickener determines the water resistance of grease. In principle, greases of different brands cannot be mixed, and even greases of the same thickener can cause bad effects due to different additives.
4, the addition of grease
When lubricating, the more grease is applied, the better. This is a common misconception. Too much grease in the SKF bearing and SKF bearing chamber will cause excessive stirring of the grease, resulting in extremely high temperatures. The amount of lubricant filled in SKF bearings is appropriate to fill 1/2 to 1/3 of the internal space of SKF bearings, and should be reduced to 1/3 at high speeds.
5. Installation and disassembly of SKF bearings
Do not directly hammer the SKF bearing end face and non-stressed surface during installation. Use a pressure block, sleeve or other installation tool to make the SKF bearing evenly stressed. Do not install it through the driving force of the rolling element. If the installation surface is coated with lubricating oil, the installation will be smoother. If the interference is large, the SKF bearing should be placed in mineral oil and heated to 80 ~ 90 ℃ as soon as possible. The oil temperature should be strictly controlled not to exceed 100 ℃ to prevent the tempering effect from reducing the hardness and affecting the size recovery. When disassembly is difficult, it is recommended that you use the disassembly tool to pull out and carefully spray hot oil on the inner ring. The heat will expand the SKF bearing inner ring, making it easier to fall off.
6, the choice of SKF bearing radial clearance
Not all SKF bearings require a minimum working clearance, you must choose the appropriate clearance according to the conditions. In the national standard 4604-93, the radial clearance of rolling SKF bearings is divided into five groups -2 groups, 0 groups, 3 groups, 4 groups, and 5 groups. The clearance values are from small to large, and 0 group is the standard clearance. The basic radial clearance group is suitable for general operating conditions, conventional temperatures and commonly used interference fits; SKF bearings that work under special conditions such as high temperature, high speed, low noise, and low friction should use large radial clearance; For precision spindles, SKF bearings for machine tool spindles, etc., smaller radial clearances should be used; for roller SKF bearings, a small amount of working clearance can be maintained. In addition, there is no clearance for the separated SKF bearings; in the end, the working clearance of the SKF imported bearings after installation is smaller than the original clearance before installation, because the SKF bearings must withstand a certain load of rotation, and SKF bearings cooperate And the amount of elastic deformation caused by the load.
SKF bearings can be divided into sliding SKF bearings and rolling SKF bearings according to the specific structure and working nature. As the name implies, the sliding SKF bearing is a flat SKF bearing with a large contact area, so the degree of wear will be relatively large, that is, the coefficient of friction is large. Therefore, sliding SKF bearings require special materials, anti-friction is its biggest feature. The characteristics of rolling SKF bearings are different from sliding. It converts the sliding friction between the shaft seat and the shaft into rolling friction, which will reduce losses. Then use the interaction of inner and outer rings, rolling elements and cage to complete the work.
Whether it is a rolling SKF bearing or a sliding SKF imported bearing, although their working principles are different, their functions are the same, all to reduce the mechanical load friction coefficient generated during the mechanical power transmission process and to support the rotating body of the machine.
SKF bearings are a kind of precision components, widely used in various fields, divided into many types according to structure or type, and the most common classification according to friction properties are rolling bearings and sliding bearings, which are also different. Obviously, the rolling bearing has less frictional resistance than the sliding bearing, and it starts quickly and has high efficiency. This is the biggest advantage of the rolling bearing compared to the sliding bearing. However, it also has the disadvantage that its size is large and its shock absorption capacity is weak. When it runs at a high speed, it has a short life span and long-term use will also produce a large abnormal noise. The most essential difference between SKF rolling bearings and sliding bearings is that rolling bearings are in surface contact, while sliding bearings are in point contact. Rolling bearings have a large contact surface, simple structure, easy operation and easy disassembly; sliding bearings have high requirements for lubrication.