After the bearing is installed, add the specified lubricant, and then perform a test run to check whether there is noise and the temperature of the bearing.
The test run should be carried out under partial load conditions. In the case of a large speed range, it should be run at medium and low speeds.
In any case, spherical roller bearings should not be started under no-load conditions and accelerated to high-speed operation, because the rolling parts may slide on the bearing raceway, damage the raceway, and the cage may also be subjected to impermissible pressure. Under normal circumstances, the bearing will emit a uniform "grunt" sound.
The bearing whistling or piercing sound indicates insufficient lubrication.
The uneven rumbling or thumping sound from the bearing is mostly due to the presence of debris in the bearing or the bearing being damaged during installation.
The bearing temperature rises immediately after starting, which is normal.
For example, in the case of grease lubrication, the bearing temperature will not drop until the grease is evenly distributed inside the bearing, after which the equilibrium temperature will be reached.
Abnormal high temperature or continuous temperature rise indicates that there may be too much lubricant inside the bearing, or the bearing has undergone radial or axial deformation, or the clearance is too small. Other reasons include improper manufacture or installation of related components, or excessive friction of seals.
During the test run or just after the test run, the seals should be checked to see if it is working properly, and the oil level of the lubricating equipment and the oil tank should also be checked. It may also be necessary to take a sample of lubricant to determine whether the inside of the bearing is contaminated or whether the components inside the bearing are worn.
Affect bearing life
Use factors and internal factors
There may be many factors that affect the service life of spherical roller bearings, which can be further explained from the use factors and internal factors.
The use factor mainly refers to whether the installation adjustment, use and maintenance, maintenance and repair meet the technical requirements.
According to the technical requirements for installation, use, maintenance and maintenance of spherical roller bearings, monitor and inspect the load, speed, working temperature, vibration, noise and lubrication conditions of the bearing in operation, and find the cause immediately if the abnormality is found. Adjust to make it back to normal.
Installation conditions are one of the most important factors in the use of factors. Bearings often change due to improper installation, resulting in changes in the stress state between the various parts of the complete set of bearings. The bearing runs in an abnormal state and ends its service life early.
The large or small force applied when installing the bearing will affect the performance and life of the bearing, and will also cause damage to the bearing. The following are four tips that need to be paid attention to in the process of applying force:
1. The applied force should be stable and uniform, without impact. This requires the use of oil pressure or tools that can apply a smooth pull or pressure. When hammering is really necessary, it must be passed through a softer copper sleeve, etc. The falling metal is cushioned, and the striking force is as gentle as possible. It is best to use a copper rod or copper hammer for hammering.
2. The application of force should continue until the work is completed. For example, when the bearing is installed, the application of force should be stopped when the bearing has just been installed in the correct position to ensure that the end face of the ring (washer) abuts against the end face of the seat hole or the shoulder of the shaft. It's too tight to fit in place.
3. The resultant force of the applied force passes through the axis of the bearing as much as possible, which requires that the force application point is uniform, symmetrical and stable, and the force is applied through a spherical surface or parallel to the axis.
4. Avoid applying force through the rolling elements, which requires applying force through the inner ring when assembling and disassembling the inner ring (shaft ring), and applying force through the outer ring when assembling and disassembling the outer ring.
As long as the force applied during the assembly and disassembly of the bearing should be stable and even, there should be no impact, and the force should continue until the work is completed. Then there will be no damage to the bearing during installation.
The metallurgical quality of spherical roller bearing materials used to be the main factor affecting the early failure of spherical roller bearings. With the progress of metallurgical technology (such as vacuum degassing of bearing steel, etc.), the quality of raw materials has been improved.
The proportion of raw material quality factors in bearing failure analysis has dropped significantly, but it is still one of the main factors affecting bearing failure. The proper selection of materials is still a factor that must be considered in bearing failure analysis.
The manufacture of spherical roller bearings generally involves multiple processes such as forging, heat treatment, turning, grinding and assembly. The rationality, advancement and stability of each processing technology will also affect the life of the bearing.
Among them, the heat treatment and grinding processes that affect the quality of the finished bearing are often more directly related to the failure of the bearing. In recent years, studies on the deteriorating layer of the bearing working surface have shown that the grinding process is closely related to the bearing surface quality.
The main task of the service life analysis of spherical roller bearings is to find out the main factors causing bearing failure based on a large number of background materials, analysis data and failure modes, so as to propose improvement measures to extend the service life of the bearing and avoid Sudden early failure of the bearing occurred.
Spherical roller bearing vibration can be divided into three types according to the vibration direction:
1. Radial vibration Vibration in the radial plane of the bearing ring.
2. Axial vibration Vibration along the axis of the bearing.
3. Angular vibration The oscillation of the radial plane of the ring relative to the diameter.
According to the generation mechanism, the vibration of spherical roller bearings can be divided into the following three types:
1. Natural vibration of bearing structure
(1) Regard the outer ring as a natural vibration caused by an elastic body.
(2) The outer ring is regarded as the natural vibration caused by the steel body.
(3) The steel ball is regarded as the natural vibration of the steel body.
2. Forced vibration
(1) Rolling elements pass through vibration Vibration caused by rolling elements periodically passing through the load line of action when the bearing is running.
(2) Vibration caused by manufacturing errors of bearing parts.
3. Shock and vibration
When there are defects such as scratches, burrs, rust spots, pitting, peeling pits and dust on the surface of the raceway of the ring or the surface of the rolling elements, the bearing will excite pulse-shaped vibration. The period of the pulse is inversely proportional to the speed, and the amplitude is related to the size of the defect.
The vibration of spherical roller bearings is often the result of the above-mentioned various types of vibration. A large number of experimental studies have shown that the waviness of the surface of bearing parts is the main factor causing bearing vibration under normal bearing operation.
