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Basic knowledge of bearing knowledge you don't know

Basic knowledge of bearing knowledge you don't know

2022-09-30

1. Precautions before installation


1. Check the bearing for quality problems. Whether the rotation is flexible, carefully check whether there are defects on the surface of the bearing parts, such as indentations, burns, cracks, etc. It is strictly forbidden to install parts with quality problems.


2. Ensure that the installation site is clean and prevent foreign objects from entering the bearing.


3. Make sure the bearing is clean, and do not install the bearing without cleaning.


4. Ensure the sealing quality. Carefully check whether the model, specification and size of the seal are suitable, whether there is any defect or quality problem, whether the relevant accessories are complete, and whether the matching is reasonable.

2. Precautions during installation


1. To avoid hard installation and impact, it is necessary to ensure that the bearing is installed lightly. The bearing and the seat hole are matched with a small gap. Under normal conditions, the end face should be installed in the positive position. The hole surface is damaged or even scrapped.


2. The installation of the inner sleeve of the spherical roller bearing must be heated by induction and should not exceed 120 °C. It is strictly forbidden to disassemble and disassemble the bearing by heating with an open flame.


3. When it is not easy to install, find out the reason, take reasonable measures after eliminating the problem, and repair it in time when it is found that there are problems such as deformation of parts, and ask to modify the drawings if necessary.


4. Inject sufficient and clean grease strictly as required.


When unqualified parts such as seals and glands are found during installation, they must be scrapped or repaired strictly to ensure that the assembly quality meets the quality requirements.

Bearing structure composition and common materials


Bearings are more reliable in use and easy to use and maintain. Let me explain to you the relevant knowledge below, I hope it will help you.


Question 1: The structure of the bearing? and structural components?


Answer 2: The structure of the bearing consists of the following parts:


1. Outer ring - installed in the bearing seat hole, generally does not rotate


2. Inner ring - mounted on the journal and rotates with the shaft


3. Rolling element - the core component of the bearing


4. Cage - evenly space the rolling elements to avoid friction


Spherical roller bearing structure: The bearing is generally composed of an inner ring, an outer ring, rolling elements and a cage. The inner ring is mounted on the journal (called the shaft ring in the thrust bearing), and the fit is tight; the outer ring is mounted in the bearing hole of the machine seat or part, and the fit is usually loose. There are raceways on the inner and outer rings. When the inner and outer rings rotate relative to each other, the rolling elements will roll along the raceways. The function of the cage is to evenly space the rolling elements. In order to meet certain application requirements, some bearings can have no inner ring or outer ring, or have dust-proof, sealing ring and other structures.


Monitoring of bearing working condition and material property requirements


1. Morphological characteristics of abrasive particles under normal conditions


During the running-in period and the normal operation period of the bearing, the size of the abrasive particles produced is generally 0.01-0.015mm, and some metal powder is mixed. The amount of abrasive debris generated during the running-in period of the new bearing is higher than that in the normal operation period, and the amount of abrasive debris and metal powder will be significantly reduced after entering the normal operation period. Abrasive fragments are microscopically thin and short in shape with irregular cross-sections.


2. Morphological characteristics of faulty abrasive particles


The main failure mode of spherical roller bearings is fatigue pitting. The size of abrasive fragments formed by rolling fatigue and spalling is generally 0.025 to 0.05 mm. Sometimes there are larger sized pieces mixed with some metal powder. Ball bearing abrasive debris generally takes the form of roughly circular, radially separated rose petals; raceway abrasive debris takes the form of roughly circular surface crushing; roller bearing abrasive debris Usually in the form of a curled rectangle with a length equal to 2 to 3 times the width; the abrasive fragments of the raceway are generally in the form of irregular rectangles.


Four conditions for bearing storage


Bearings are precision bearings with a special structure. Special care is also required when storing it. The accuracy and quality of bearings can only be maintained in a suitable environment.


1. The bearing should be stored in a clean and dry environment, and the temperature and humidity should be controlled during handling and storage. The temperature and humidity should be within an acceptable fixed range and should be more than 30cm away from the ground.


2. Some bearings have a certain shelf life. For example, for a bearing with a dust cover and an oil seal, when stored for a period of time, the starting torque of the bearing will be larger than that of a new bearing. At the same time, because the lubricating performance of the grease will be destroyed after a long period of storage, the bearing should be checked regularly. maintenance.


3. To ensure the normal and reliable operation of the bearing, sufficient lubrication must be applied to prevent direct metal contact between the rolling elements, raceways and cages, resulting in wear and corrosion of the bearing surface. Therefore, in various applications, the selection of appropriate lubricants and lubrication methods is extremely important, and at the same time, correct maintenance is also required.


The actual choice of lubricant is mainly based on operating conditions, ie: temperature range and rotational speed as well as surrounding environmental influences. If reliable lubrication can be ensured, when the amount of lubricant used in the bearing is the smallest, its operating temperature will be increased, but at the same time when it plays other functions, such as sealing or heat dissipation, the amount will be increased. Therefore, when installing the bearing, it is generally necessary to fill the remaining space of the spherical roller bearing with grease, and control 1/3-1/2 of the remaining space of the bearing box, which is easy to generate high temperature.

(Longteng, a great power in the world, Dragon out of the East, Tengda world, Longteng three types of spherical roller bearings, Liu Xingbang CA CC E MB MA)


Four stages of bearing failure development


Check the bearings that have been dismantled during the regular maintenance of the equipment, the running inspection and the replacement of peripheral parts, so as to judge whether it can be used again or whether it is good or bad.


In the initial stage, the noise is normal, the temperature is normal, can be measured by ultrasonic, vibration peak energy, acoustic emission, the bearing outer ring is defective, the total vibration is relatively small, there is no discrete bearing fault frequency peak, and the remaining life is greater than 10%.


The second stage, the noise is slightly increased, the temperature is normal, the ultrasonic, acoustic emission, the vibration peak energy is greatly increased, the bearing outer ring is defective, the total vibration is slightly increased (the total vibration acceleration and the total vibration speed) logarithmic The bearing failure frequency can be clearly seen on the scale spectrum, which is rarely seen on the linear scale spectrum, the noise level is significantly improved, and the remaining life is 5%.


Stage 3, audible noise, slightly elevated temperature, very high ultrasound, acoustic emission, vibration peak energy, faulty bearing outer ring, large increase in total vibration acceleration and total vibration velocity, in linear scale The frequency spectrum clearly shows that the bearing fault frequency and its harmonics and sidebands, the vibration spectrum noise level is significantly improved, and the remaining life is less than 1%.


The fourth stage, the intensity of the noise changes, the temperature rises significantly, the ultrasonic, acoustic emission, the vibration peak energy increases rapidly, and then gradually decreases, the bearing outer ring is in the fault state before the damage, the total vibration velocity and the total vibration displacement Significantly increased, the total amount of vibration acceleration decreased, the lower failure frequency of the spherical roller bearing dominated the vibration peak, the noise level in the vibration spectrum was very high, and the remaining life was less than 0.2%.


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