Technical requirements for Timken non-standard bearing
With the development of science and technology, the rotating speed of machine tool spindle is higher and higher, and the speed range is larger and larger. Therefore, the requirements for the stability of bearing high-speed operation are higher and higher. The temperature rise of machine tool spindle bearing is an important factor to limit the bearing speed.
Generally, the correct selection of non-standard bearing type, tolerance grade, configuration mode, clearance (preload), lubricant and lubrication mode can improve the high-speed performance of rolling bearing to a certain extent.Technical requirements for Timken non-standard bearing
Technical requirements for Timken bearing of main shaft
2. Service life and bearing capacity:
For general machine tools, the service life of the spindle assembly mainly refers to the service life of maintaining the spindle accuracy. Therefore, the accuracy maintenance performance of the bearing is required to meet the requirements of the service life of the spindle assembly. For heavy machine tools or power cutting machine tools, the bearing capacity of non-standard bearings should be considered first.
Rolling bearings make precision parts, so it is required to be cautious when using them. Since high-performance bearings are used, if they are not used properly, they can not achieve the expected performance effect. Therefore, the following matters should be paid attention to when using bearings:Technical requirements for Timken non-standard bearing
Technical requirements for Timken non-standard bearing
Keep non-standard bearings and their surroundings clean. Even if the small dust invisible to the naked eye enters the bearing, it will increase the wear, vibration and noise of the bearing.
When using and installing, it shall be careful. It is not allowed to punch with force, directly knock the bearing with a hammer, and transfer pressure through the rolling body.Technical requirements for Timken non-standard bearing
Use proper and accurate installation tools, try to use special tools, and try to avoid using cloth and short fiber.Technical requirements for Timken non-standard bearing
To prevent the corrosion of Timken bearing, when taking the bearing directly by hand, fully wash the sweat from your hands and apply high-quality mineral oil
The inner diameter and outer diameter of rolling bearings are manufactured according to standard tolerances. The fit tightness of bearing inner ring and shaft, outer ring and seat hole can only be realized by controlling the tolerance of journal and seat hole. The matching of non-standard bearing inner ring and shaft adopts base hole system, and the matching of bearing outer ring and seat hole adopts machine shaft system.
To correctly select the fit, you must know the actual load conditions, working temperature and other requirements of Timken bearing, which is actually very difficult. Therefore, in most cases, the matching is selected according to the use of fine grinding.Technical requirements for Timken non-standard bearing
The win-win amount between the ferrule and the shaft or shell depends on the load. The heavier load adopts the larger win-win amount, and the lighter load adopts the smaller win-win amount.Technical requirements for Timken non-standard bearing
Damage state: the so-called wear is the wear of raceway surface or rolling surface, roller end face, shaft ring surface and concave surface of cage caused by friction.
Cause: development caused by foreign matter intrusion, rust and electric corrosion. Poor lubrication. Slippage caused by irregular movement of rolling elements.
Measures: improve the sealing device. Clean the bearing housing. Fully filter the lubricating oil. Check the lubricant and lubrication method. Prevent non-linearity.
Micro vibration wear
Damage state: wear caused by relatively repeated small sliding between the two contact surfaces occurs on the contact part between the raceway surface and the rolling element. Due to the occurrence of reddish brown and black wear powder, it is also called micro vibration wear corrosion.
Cause: poor lubrication. Small amplitude rocking motion. Insufficient interference.
Action: use proper lubricant. Preload. Check the interference. Apply lubricant to the mating surface
Pseudo Brinell indentation
Damage state: the so-called creep refers to the relative sliding between the mating surfaces when there is a gap on the mating surface of Timken bearing. In terms of the mating surface with creep, the mating surface presents a bright or dark mirror surface, and sometimes the page is damaged and worn.
Cause: insufficient interference or clearance fit. The fixing sleeve is not tightened enough.
Measures: check the interference and implement anti rotation measures. Tighten the set sleeve properly. Study the accuracy of shaft and bearing housing. Axial preloading. The side of the raceway wheel is fastened. Bond the mating surface. Apply to the mating surface? Lubricant.
burn
Damage state: the raceway wheel, rolling element and cage are heated sharply during rotation until they change color, soften, deposit and damage.
Cause: poor lubrication. Excessive load (excessive preloading). Excessive speed. The clearance is too small. Intrusion of water and foreign matters. The accuracy of shaft and bearing box is poor and the deflection of shaft is large.
Measures: study lubricants and lubrication methods. Correct the selection of bearings. Study fit, bearing clearance and preloading. Improve the sealing device. Check the accuracy of the shaft and bearing housing. Improve installation methods.
Electroerosion
Damage state: the so-called electric erosion refers to the phenomenon that when the current flows in the contact part between the bearing raceway wheel and the rolling body, sparks are sent out through the thin lubricating oil film, and local melting and concave convex appear on its surface.
Cause: ground potential difference between outer ring and inner ring.
Measures: when setting the circuit, the current should not flow through the bearing part. Insulate the bearings.Technical requirements for Timken non-standard bearing
Rust and corrosion
Damage state: the rust and corrosion of bearings include pit rust, overall rust and corrosion on the surface of raceway wheel and rolling element.
Cause: invasion of water and corrosive substances (paint, gas, etc.). Improper lubricant. Water droplets are attached due to the condensation of water vapor. Stop when it is hot and wet. Poor rust prevention during transportation. Improper storage status. Improper use.Technical requirements for Timken non-standard bearing
Measures: improve the sealing device. Study lubrication methods. Rust prevention measures during shutdown. Improve storage methods. Pay attention when using.Technical requirements for Timken non-standard bearing
Installation scar
Damage state: axial linear scars on the raceway surface and rolling surface during installation and disassembly
Cause: the inner ring and outer ring during installation and disassembly are inclined, and the impact load during disassembly.Technical requirements for Timken non-standard bearing
Measures: use appropriate tools and press to prevent impact load. Centering between each other during installation.Technical requirements for Timken non-standard bearing
Discoloration
Temperature change and roller cage damage due to lubricant and reaction.
Cause: poor lubrication. Reaction with lubricant causes hot oil immersion. The temperature rises greatly.Technical requirements for Timken non-standard bearing
Measures: improve lubrication methods.Technical requirements for Timken non-standard bearing
It can be seen from the above that the axial clearance of Timken bearings with adjustable or non adjustable clearance shall be adjusted during assembly (but some bearings with non adjustable clearance do not need to leave axial clearance) to compensate for the thermal elongation of the shaft when the temperature rises, so as to ensure the normal operation of the thrust ball bearing body. Technical requirements for Timken non-standard bearing
If the axial clearance is too small, it will make the bearing difficult to rotate, heat, and even make the bearing body stuck or damaged; If the axial clearance is too large, it will cause abnormal sound during operation, and even cause serious vibration or damage to the cage.Technical requirements for Timken non-standard bearing
Power operation, starting from no-load and low speed, slowly increase to the rated operation under the specified conditions. During the test run, the inspection items are whether there is abnormal sound, temperature change of railway bearing, leakage or discoloration of lubricant, etc.
If any abnormality is found, stop the operation immediately, check the machinery, and remove the bearing for inspection if necessary.Technical requirements for Timken non-standard bearing
The bearing temperature can generally be inferred from the external temperature of the bearing seat. However, it is more accurate to directly measure the temperature of the bearing outer ring by using the oil hole. Technical requirements for Timken non-standard bearing
The bearing temperature rises gradually from the beginning of operation, and the temperature is usually stable after 1 ~ 2 hours. If ina bearing is not installed properly, the temperature will rise sharply, resulting in abnormal high temperature.Technical requirements for Timken non-standard bearing
The reasons are too much lubricant, too small bearing clearance, poor installation, excessive friction of sealing device, etc. In the case of high-speed rotation, the wrong selection of railway bearing structure and lubrication mode is also the reason.
The rotation of the bearing is checked with a stethoscope, and there are strong metal noise, abnormal sound, irregular sound and other abnormalities. The reasons are poor lubrication, poor accuracy of shaft or bearing seat, bearing damage, foreign matter intrusion, etc.Technical requirements for Timken non-standard bearing
There are two kinds of lubricants commonly used in rolling bearings: lubricating oil and grease. When the circumferential speed of the shaft is less than 4-5m / s, or the parts on the vehicle that cannot be lubricated with lubricating oil, they shall be lubricated with grease. Technical requirements for Timken non-standard bearing
The advantage of grease lubrication is that the sealing structure is simple, the grease is not easy to lose, and it is not affected by temperature. Adding grease once can be used for a long time.
The advantage of lubricating oil lubrication is low friction resistance and heat dissipation. It is mainly used for railway bearings with high speed and high working environment temperature. The brand of lubricating oil shall be selected according to the requirements of the vehicle manual, and shall be replaced in time after the vehicle maintenance cycle. Technical requirements for Timken non-standard bearing
After discharging the old oil, the mechanism shall be cleaned before adding new oil. The oil shall be added to the specified marking line or flush with the oil filler (depending on the specific structure and requirements of the vehicle), and no more oil shall be added.Technical requirements for Timken non-standard bearing
Bearing is an important mechanical component. Whether the performance of a mechanical equipment can be brought into full play depends on whether the lubrication of the bearing is appropriate. It can be said that lubrication is a necessary condition to ensure the normal operation of INA Bearing. Technical requirements for Timken non-standard bearing
It plays an important role in improving the bearing capacity and service life of railway bearing. No matter what form of lubrication is adopted, lubrication can play the following roles in the bearing:Technical requirements for Timken non-standard bearing
(1) Reduce the friction between metals and slow down their wear.
(2) The formation of oil film increases the contact area and reduces the contact stress.Technical requirements for Timken non-standard bearing
(3) Ensure that the bearing can operate normally for a long time under high-frequency contact stress and prolong the fatigue life,
(4) Eliminate friction heat, reduce the temperature of bearing working surface and prevent burns.
(5) It can prevent dust, rust and corrosion.
Therefore, proper lubrication is very important for the normal operation of INA Bearing. The lubrication design of railway bearings mainly includes the determination of reasonable lubrication methods, the correct selection of lubricants, the quantitative calculation of lubricant dosage and the determination of oil change cycle.Technical requirements for Timken non-standard bearing
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