During the use of rolling bearings, due to their own quality and external conditions, their bearing capacity, rotation accuracy and anti-friction performance will change. When the performance index of the bearing is lower than the use requirements and cannot work normally, it is called bearing damage. Or failure, once the bearing is damaged and other unexpected situations, there will be various abnormal phenomena such as machine and equipment stop, function damage and so on.
If the bearing is broken, we must first analyze the cause of the failure, and then find a solution. Therefore, it is necessary to investigate and deal with the reasons in the short term and take corresponding measures.
The factors that cause the bearing to become old and bad are mostly caused by improper use of the bearing? The following is an explanation of the factors that cause the bearing to be damaged frequently. China Bearing Network shares the following:
Bearings are lossy parts, they will definitely be damaged as long as they are used, but only after a certain amount of accumulation will they appear. That is to say, they will not be damaged until a certain amount. Of course, the damage of rolling bearings is more complicated than that of general mechanical parts. The damage of rolling bearings is characterized by many manifestations and complex reasons. In addition to the inherent factors of bearing design and manufacture, most of the damage of bearings is due to improper use, such as: suitable type selection cloth, unreasonable support design, improper installation, It is caused by external factors such as poor lubrication and poor sealing. The following 8 points are the main factors for bearing failure:
1. Metal corrosion occurs. If there is a lack of lubrication, it is easy to be oxidized by the air and rusted. To prevent the rust of the bearing, do not use blisters. The bearings are made of stainless steel, but they are also afraid of water. When handling the bearing by hand, fully wash off the sweat on the hands, and apply high-quality mineral oil before operating, especially in the rainy season and summer, pay special attention to rust prevention.
The specific reasons for the natural corrosion and wear of bearings are mainly as follows:
①Oxidation wear. The tiny peaks and valleys on the friction surface squeeze each other, causing the brittle surface to gradually fall off and wear. The tiny peaks and valleys on the surface of the relative motion of the bearing are synthesized with the oxidation in the air to form a brittle oxide that is not firmly bonded to the base metal. The oxide is easy to fall off during friction, and the wear that occurs is called oxidation wear.
②Friction heat and wear. When the bearing works under the condition of high speed and heavy load and poor lubrication, the peaks and valleys of the surface will generate high temperature due to friction, the hardness and wear resistance of the contact points will decrease, and even adhesion and tearing will occur. This kind of wear is called frictional heat wear.
③ Hard particle wear. If the bearing is in relative motion. The moving surface of the bearing is unevenly organized, and there are hard particles, or impurities such as sand, friction and chips fall into the moving surface of the bearing. During the relative motion of the bearing, the hard particles or impurities will scratch the surface of the bearing or even form grooves. This type of wear is called hard-grain wear.
④ Pitting wear. Gears, bearings and other rolling contact surfaces are periodically subjected to a large contact pressure in the relative process. After a long period of time, the metal surface is fatigued, causing tiny cracks and erosion on the bearing surface. This kind of wear is called pitting wear.
Causes rust or corrosion, wear caused by chemical corrosion. The bearing surface is corroded by acid, alkali, salt liquid or harmful gas. The wear process is accelerated, which is called wear caused by chemical corrosion.
Corrosion damage due to temporary contact with liquids such as water, acid, alkali, salt, or harmful gases: non-moving bearings on equipment. Damage caused by rust or corrosion is called corrosion damage.
2. The bearing load is too large or improperly used. When using it, the load of the bearing cannot be exceeded. Like a car, it may be that the load is too heavy, which will easily damage the bearing. Therefore, the truck has more problems than the car, which is caused by many parts that cannot withstand it.
3. The bearing clearance is too small. The front wheel of the car is a slant-push bearing, and the clearance needs to be adjusted. If it is too loose, it will cause abnormal noise, deflection, and wheel shaking. If it is too tight, it will accelerate the wear. Both are bad. Check the ball surface for burrs, scratches and cracks. Whether the radial clearance and axial clearance of the old bearing are qualified, generally only the radial clearance is measured. For new bearings, first check that the bearing type is correct. Refer to Table 1 for the radial clearance standards of rolling bearings. For example: Model 6318 deep groove ball bearing, the inner diameter of the bearing is 90mm, the radial clearance range is 0.016 ~ 0.046mm, and the maximum wear amount of the bearing can also be found to be 0.25mm.
Table 1
4. Use inferior bearings. The production of bearings is produced by some small factories. The production process cannot meet the requirements, the accuracy of the shaft or bearing box is poor, and the bearing steel is not processed before pressing. Therefore, the produced bearings are not durable.
5. Reckless driving may also cause the car bearing to be damaged, but this reason is a bit far-fetched. Because if you drive carelessly, other parts will be damaged before the bearing.
6. Poor installation. To install the bearing is to follow the installation steps of the bearing, do not install and disassemble brutally. Whether the bearing is installed correctly is related to the service life of the bearing, so everyone must pay attention to it. When installing the bearing, avoid holding it directly by hand, because the sweat on the hand may also cause rust, and do not ignore the small links. When the bearing is installed, the most important thing is not to allow strong stamping, not to hit the bearing directly with a hammer, not for fear of being smashed, but for fear of being smashed and deformed, and the bearing cannot be used if it is deformed. Also, it is not allowed to transmit pressure through the rolling elements.
7. Foreign body intrusion. Use special tools as much as possible, and try to avoid the use of cloth and short fibers, so as to prevent fine fibers from entering the bearing and causing unnecessary damage. For another example, when installing the bearing, the staff used the copper rod knocking method, which is easy to cause uneven axial force on the bearing, resulting in deformation of the cage, damage to the rolling elements, and increased clearance. The copper powder flies into the bearing cage, which is easy to cause bearing failure. Also, during use
8. The hardness caused by abnormally high temperature, the metallographic structure or chemical composition of the metal changes, which reduces the wear resistance and hardness of the bearing surface and accelerates the wear process. This kind of wear is called wear caused by high temperature action. Wear caused by high temperature action. When the bearing is temporarily operated at a high temperature.
9. Too much oil in the bearing and the box will cause the bearing rolling element to slip, causing the rolling element to change from rolling friction to sliding friction, and damage the bearing rolling element. Due to the excessive amount of bearing oil, the free space in the bearing box is small, and the running of the bearing The temperature will rise, the degree of grease will decrease, the lubricating oil film of the rolling element will become thinner, and the lubricating conditions will be poor, which will easily cause abnormal noise of the bearing, slip on the surface, and shorten the life of the bearing. Generally, there is a bearing oil chamber on the side of the motor end cover. According to the speed of the motor, the oil filling amount of the bearing chamber can be implemented according to the following standards: when the motor speed is less than 1500r/min, the oil filling amount is 2/3 of the bearing chamber volume. When the speed is between 1500 and 3000r/min, it is 1/2 of the bearing chamber volume. When the speed is more than 3000r/min, it should be less than or equal to 1/3 of the bearing volume. In the actual working process, for the bearings running at high temperature and high speed, the bearings with sealing surfaces should be used as little as possible, the oil storage capacity of the motor oil cap should be increased, and the oil nozzles should be installed to improve the operating life of the motor bearings.
10. For bearings with insulating design on the outer ring, care should be taken to ensure that the insulation is intact. If the bearing insulation is damaged during installation, the very thin bearing oil film will be broken down by the shaft voltage. After the oil film is broken down, not only the lubrication conditions of the rolling elements will be bad, but also the electric sparks generated will cause electrical corrosion to the rolling elements of the bearing, causing rolling elements. The surface is not smooth, which accelerates the wear of the bearing.
Bearing wear can be repaired in this way. The solution is: it is necessary to re-study the conditions of use or re-select the bearing, observe the clearance and check the machining accuracy between the shaft and the bearing strip, check the design around the bearing, and study and check the installation method, lubricant and lubrication method.
Bearing wear can be repaired in this way/step
1. Do the preparatory work, that is, the dismantling of the equipment, to ensure sufficient construction space and a safe working environment;
2. Preliminary cleaning of the shaft surface, that is, wipe clean the oil stains on the bearing position and the surface of the positioning surface, and remove high points, burrs, rust layers, etc., use 99.7% anhydrous ethanol to clean the bearing position surface to ensure that there is no dirt, to dry;
3. Wipe the inner and outer surfaces of the mold clean, and wipe a thin layer of SD7000 mold release agent on the inner surface of the mold, discharge chute, bolts, bolt holes, positioning pins, and positioning pin holes, the thinner the better, dry for use;
4. The material SD7101H is blended in strict accordance with the proportion to volume ratio of 2:1, the blending is sufficient and there is no color difference, and the blended material is quickly applied to the surface of the bearing position;
5. Quickly install the mold in place, fasten the bolts and install the positioning pins. In the process of installing the mold, pay attention to observe the mold to avoid the axial movement of the mold, and use a rubber hammer to hit the mold in the circumferential direction during the process of tightening the mold to make the material distribution more uniform and avoid the deformation of the mold;
6. Material curing: when the ambient temperature is 24 °C, it is recommended to remove the mold for no less than 4 hours; when the ambient temperature is below 24 °C, it is recommended to use an iodine tungsten lamp to heat for no less than 3 hours;
7. Be careful when dismantling the mold to avoid material damage or falling off during the disassembly process. After the mold is disassembled, use a saw blade or a cutting blade to remove the excess material extruded from the discharge chute, and at the same time grind it below the overall surface;
8. Assembling parts: When assembling parts, it is recommended to apply a thin layer of mold release agent to the mating surface of the parts in advance, and apply a thin layer of material to the bearing surface, and install them quickly in strict accordance with the assembly process.