High temperature often indicates that NTN bearing is in abnormal condition. High temperature is also harmful to the lubricant of the bearing. Sometimes bearing Ntn Ball Screw Bearings overheating can be attributed to the lubricant of the bearing.
If the temperature of the bearing exceeds 125 ℃ for a long time, the service life of the ball screw bearing can be reduced. The causes of high temperature bearings include insufficient or excessive lubrication and lubricant. It contains impurities, excessive load, bearing ring damage, insufficient clearance, high friction caused by oil seal, etc.
Compared with ordinary mechanical parts, the precision of ball screw Ntn Ball Screw Bearings bearing is higher, so care should be taken when using it.
1. Keep NTN bearings and their surroundings clean.
2. Be careful when using: if the bearing is carelessly impacted, the bearing will be damaged, indentation, fracture and so on.
3. Use appropriate tools.
4. Pay attention to the rust prevention of the bearing. Avoid using in wet places, and wear gloves to prevent sweat.
5. Users should be familiar with bearings.
Lubricating oil lubrication has the advantages of low friction resistance and heat dissipation. It is mainly used for high-speed ball Ntn Ball Screw Bearings screw bearings and NTN bearings with high working environment temperature.
The brand of lubricating oil shall be selected according to the Ntn Ball Screw Bearings requirements of the vehicle manual, and shall be replaced in time after the vehicle maintenance cycle. 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.
The lubrication interval has a simple premise: keep the equipment running reasonably under the condition that the ball screw bearing does not stop running due to drying and collapse. This is a fixed concept of prevention. However, we must maintain a balance between lubrication hunger and excessive lubrication.
Traditionally, lubrication planning is based on time. Equipment suppliers usually make lubrication plans according to the operation time. Moreover, equipment suppliers Ntn Ball Screw Bearings often add guidance on the amount of lubricating oil in their maintenance planning process.
It is very common to change lubricating oil for a short time, and more lubricating grease is often added. If the staff is required to change the lubricating oil every two to three weeks, add one ounce of grease each time. From the beginning, these suggestions led to their establishment on unknown factors that have no practical significance.
From the fact that peeling, indentation, corrosion, crack and wear will be reflected in the Ntn Ball Screw Bearings vibration measurement of the bearing, the vibration of NTN bearing is very sensitive to the damage of the bearing.
Therefore, the vibration of angular contact ball bearing can be measured by using a special Ntn Ball Screw Bearings bearing vibration meter (frequency analyzer, etc.), and the specific abnormal situation can not be inferred by frequency division.
Because the measured values are different due to the service Ntn Ball Screw Bearings conditions of the bearing or the installation position of the sensor, it is necessary to analyze and compare the measured values of each machine in advance to determine the judgment standard.
Because NTN bearing will emit abnormal sound and irregular sound even if there is slight peeling and other damage, it can be distinguished by sound detector. The sound detector is used to check the rolling sound and sound quality of angular contact ball bearing in operation, which plays the role of prevention in advance.
If the oil hole can be used to directly measure the temperature of the bearing outer ring, it is more Ntn Ball Screw Bearings appropriate. Generally, the temperature of NTN bearing can be inferred from the temperature outside the bearing chamber.
If the lubrication and installation parts are appropriate, the bearing temperature will rise sharply and abnormal high temperature will occur. At this time, the operation must be stopped and necessary preventive measures must be taken.
Usually, the temperature of the bearing rises slowly with the start of operation and reaches a stable state after 1-2 hours. The normal temperature of angular contact ball bearing varies with the heat capacity, heat dissipation, speed and load of the machine.
If necessary, the thermal sensor can be used to monitor the working temperature of the bearing at any time, and automatically alarm or stop when the temperature exceeds the specified value to prevent the occurrence of combustion shaft accident.
The assembly of NTN bearing is the basic operation in fitter’s assembly and repair, and the adjustment and pre tightening of clearance is an important link in the assembly of rolling bearing.
Accurately grasping the process concept of clearance adjustment and pre tightening and correctly using this process method in the assembly work is the guarantee of the quality of bearing assembly work.
The clearance of NTN bearing refers to the large amount of movement made by the other ring along the radial or axial direction when one ring is fixed, so the clearance is divided into radial clearance and axial clearance. When assembling angular contact ball bearings, the clearance should not be too large or too small.
Too large clearance will reduce the number of rolling elements bearing load at the same time and increase the load of a single rolling element, so as to reduce the rotation accuracy and service life of the bearing; If the clearance is too small, the friction will increase,
the heat generated will increase, and the wear will be intensified, which can also reduce the service life of the bearing. Therefore, the clearance of bearings should be strictly controlled and adjusted during assembly.
Pre tightening is to give an axial force to the inner ring or outer ring during bearing assembly to eliminate the bearing clearance and make the initial deformation at the contact between the rolling element and the inner and outer rings.
Preloading can improve the stiffness and rotation accuracy of the bearing in the working state. Most bearings with large load and high rotation accuracy requirements work in the state of no clearance or even a small amount of interference.
In this case, it is necessary to preload the bearing during assembly. The clearance adjustment and pre tightening are usually completed by making appropriate axial relative displacement of the inner ring to the outer ring. From the above technological concepts,
it is not difficult to see that the bearing capacity and rotation accuracy of the bearing can be improved and the service life of the bearing can be improved by adjusting the clearance of the diagonal contact ball bearing. But at the same time,
it will aggravate the friction of NTN bearing and increase the calorific value. Therefore, good lubrication and heat dissipation must be ensured when adjusting the clearance or preload.
If the adjustment is improper or the lubrication is poor, the bearing wear will be intensified and the service life will be reduced. To correctly adjust and pre tighten the bearing clearance, pay attention to the following problems.