[Guide] Bearings are very precise parts. The maintenance and maintenance of bearings directly determines the safety and service life of the motor. Any motor manufacturer should pay special attention to the performance compliance of the bearing. On the one hand, it should make a choice on the choice of bearing model. On the other hand, it should evaluate and control the tolerance of the parts and components that cooperate with the bearing.
For mechanical and electrical faults of motors, bearings are components that are directly related to both problems. Ms.'s statistics and analysis of faulty motors over the years have found that the two types of faults are basically positively correlated. If the motor performance is better Can not ignore any links related to it, experience tells us that for motor products, the selection of bearings is very important, it is necessary to maintain and maintain the bearings well.
Bearings are very precise parts. The maintenance and maintenance of bearings directly determines the safety and service life of the motor. Any motor manufacturer should pay special attention to the performance compliance of the bearing. On the one hand, it should make a choice on the choice of bearing model. On the other hand, it should evaluate and control the tolerance of the parts and components that cooperate with the bearing.
The role and type of bearing cage
A bearing cage, also called a bearing retainer, refers to a bearing part that partially wraps all or part of the rolling elements and moves with it to isolate the rolling elements. It usually also guides and holds the rolling elements in the bearings.
The cage plays a role of isolating the rolling elements and preventing the rolling elements from falling down in the rolling bearings, guiding and driving the rolling elements to rotate. The first damaged part of a bearing is often a cage. The cage can be said to be a "rib" of the bearing. The rolling elements are evenly and orderly distributed, allowing the rolling elements to move freely and evenly between the inner and outer rings. The load acts on the inner ring and the outer ring at a constant speed. Damage to the cage causes the rolling elements to become stuck or its surface to be corroded to make the rolling elements fail to rotate, which can easily shorten the service life of the bearings, increase noise, and even damage them.
The types of cage materials include low carbon steel stainless steel cages, bakelite, nylon cages, brass, bronze and aluminum alloy cages.
● Steel cages are stamped and solid; steel plates or steel forgings are used; this cage has high strength and lighter material; it is mostly used for deep groove ball bearings, spherical roller bearings and most tapered roller bearings, generally not Affected by mineral oil-based or alkaline oil-based lubricants of rolling bearings; but this kind of cage is susceptible to rust by the influence of water and water vapor; the operating temperature of the cage can reach 300 ° C.
● Brass cages are also available in stamping and solid. Stampings are only suitable for small and medium-sized bearings; the materials include brass plates, brass castings or brass forgings; they are equivalent to steel stamping cages, but their density is relatively small and the limit speed High; the cage is not affected by lubricants, including synthetic oils and greases; but brass cages can not be used above 300 ℃ (operating temperature below 300 ℃), not suitable for ammonia cooling, because ammonia will Cause seasonal cracking of brass;
● Polyamide cage is a solid cage (injection molding method); due to the advantages of polyamide nylon material with high elasticity and light weight, this cage has very good sliding and self-lubricating properties. It is especially suitable for situations with vibration shock stress or high acceleration and deceleration, or when the inner and outer rings of the bearing are inclined to each other; but the polyamide nylon cage may be affected by special lubrication; it cannot be used in vacuum because it will be dehydrated It becomes brittle; its working temperature is lower than -40 ° C to 120 ° C. If the temperature is too low, nylon will lose its elasticity.
Why is the bearing cage damaged?
● Insufficient bearing lubrication. Lubricating oil or grease is dried up and not added in time (maintenance); this is the most common fault in motor failures. Some are because the motor manufacturer does not fully understand the operating conditions of the motor. The selected grease does not meet the requirements. The motor used by the customer failed to replenish grease as required.
● The impact load of the bearing. The intense vibration in the impact load produces the impact of the rolling elements on the cage. This problem is more common in motors supporting ball mills. In order to avoid this problem, many motor manufacturers have basically solved the problem after replacing ball bearings with column bearings.
● Bearing cleanliness. Due to improper protection during the assembly or use of the motor, dust enters, causing serious friction between the rolling elements and the cage, which damages the cage.
● Installation problems. Bearings are installed incorrectly and the cage is damaged during installation. Ms. has seen the fact that the bearing is directly pressed on the cage during the press-fitting process of the bearing, and the final result is a batch noise of the motor. This kind of problem exists in many motor factories. It is recommended that bearing manufacturers communicate with bearing customers on a regular basis. Through necessary and reasonable tooling design and supplementation, similar problems will be much less.
● Bearing creep phenomenon. When the interference amount of the mating surface is insufficient, the load point moves to the surrounding direction due to sliding, which results in the phenomenon that the relative position of the ferrule relative to the axis or the housing is shifted in the circumferential direction, which is also the problem of running circles. For better motor manufacturers, the machining precision of bearing positions and bearing chamber diameters is high, which makes the bearings in excellent running condition after assembly, which also guarantees the service life of the bearings.
● Abnormal load on the bearing cage. Due to problems such as incomplete installation, tilt, and excessive interference, it is easy to reduce bearing clearance, increase friction and heat, and cause the bearing surface to soften and cause abnormal peeling. With the expansion of the spalling, the spalling foreign matter enters the pocket of the cage, which causes the cage to block operation and generate additional load, which exacerbates the wear of the cage. Such a deteriorating cyclic effect is likely to cause the cage to break. The end result is Bearings fall apart.
● Defective bearing cage material. The cage itself has cracks, foreign objects, shrinkage holes, air bubbles, and riveting defects. Missing nails, pad nails, or gaps on the joint surface of the two halves of the cage, and severe rivet injuries may cause the cage to break. This is a quality problem of the bearing itself, but it is almost impossible for the bearing manufacturer to regulate the production.
● Other reasons. If the coupling is misaligned during the installation and use of the motor, the bearing will be skewed and the force will be uneven; the belt installation will be too tight; environmental problems, etc. may damage the bearing or the cage.
Record nuber Gangdong ICP NO :17115209