Reasons for affecting the circularity of the inner ring of a rolling bearing

1. The circularity of the inner ring of the rolling bearing is an important quality index, which directly affects the working accuracy, stability and service life of the bearing. Grinding is usually a semi-finishing or finishing process of the inner ring channel, which plays a decisive role in the roundness of the inner ring channel. The roundness of the inner ring channel grinding depends on the accuracy and dynamics of the grinding process system. In addition to the characteristics, it is also closely related to the process parameters of the grinding. The former has been valued by many scholars and has carried out a lot of research, which has greatly improved the roundness of the inner ring of the grinding inner ring. With the improvement of the precision of the grinding process system and the improvement of the dynamic characteristics, the grinding process parameters become the main factors affecting the roundness. Therefore, the influence of the grinding process parameters on the roundness is studied, and the process parameters are ensured to ensure the bearing channel. The grinding roundness and the optimization of the process parameters for grinding the bearing channel are of great significance.

2. The inner ring of the bearing is usually cut into the grinding mode by variable feed rate. The grinding cycle can be divided into four stages: rapid approach, coarse feed, fine feed and no feed grinding. The main factors affecting the roundness of the grinding bearing channel can be summarized as: (1) the accuracy of the process system during the grinding process, which depends on the accuracy of the grinding machine and the positioning principle of the fixture, structural parameters and accuracy: (2) the process system Dynamic characteristics, especially the balance of the grinding wheel: During the dressing and grinding process, the grinding wheel is unbalanced, which will cause forced vibration. The relative position of the dresser and the grinding wheel and the relative position of the workpiece and the grinding wheel during grinding are different due to the dressing of the grinding wheel. And the difference in the stiffness of the process system in these two different cases makes the surface of the workpiece caused by vibration not round: the grinding process parameters will affect the contact stiffness between the grinding wheel and the workpiece, the wear process of the grinding wheel and the damping characteristics of the vibration of the process system. Therefore, the vibration characteristics of the grinding process are affected, which is ultimately reflected in the geometry (ie roundness) and other surface quality of the grinding workpiece: (3) The original error of the workpiece caused by the elastic deformation of the process system: analysis of the grinding cycle workpiece The variation law of geometric shape error shows that the geometric error of the workpiece after grinding is mainly determined by the stiffness of the process system and grinding. Cutting process parameters, grinding wheel wear speed and original workpiece error? Considering the above influencing factors, when the stiffness and dynamic characteristics of the process system are constant (especially the grinding wheel must be well balanced), the roundness error of the grinding workpiece depends mainly on the grinding process parameters, so the roundness test data can be passed. The stepwise regression modeling, selecting important parameters from multiple process parameters, and gradually introducing regression equations, to establish an optimal regression equation for the relationship between grinding roundness and process parameters.

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Bearing speed limit index

In the general bearing model table, there will be a speed limit indicator. What does it mean?

When the bearing exceeds a certain operating speed, it will begin to generate uncontrolled internal heat.

The speed limit varies with bearing type, size, lubrication system, bearing internal design, and operating load. In addition, the speed limit will vary depending on the type of composite seal used (depending on the speed of the seal contact zone).

The term "speed limit" generally refers to the estimated speed, the number of revolutions per minute at which the bearing will remain operational.

The limit speeds for grease lubrication and oil lubrication are given in the general dimensions table. This value is based on bearings that are mounted on a horizontal shaft, suitable for lubrication operation, and light loads.

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Some knowledge of bearing heating failure

Bearing consultation to form a knowledge of bearing heating failure

The bearing is a fixed part of the machine and is the main body of the machine. Its function is basically to maintain the center position of the shaft and the mechanism for controlling the movement. Bearings play a decisive role in any machine. If there are no imported bearings, the machine will not work.

Many users have reported that when using bearings, the failure of bearing heating is the most common, and this failure will also affect the life and performance of the bearing. So how is this failure formed? Below, is the knowledge that is summarized for everyone.

1. The oil level is too low and the lubricant is lost from the oil seal;

2. The grease in the bearing housing is completely filled or the oil level is too high. This can lead to excessive lubrication, high temperature or oil leakage;

3. The contact type (friction) oil seal is too dry or the spring is too tight;

4. The inner hole of the bearing box is not round; the bearing box is twisted and deformed; the bearing surface is not flat; the inner diameter of the box hole is too small;

5. The contact type (friction) oil seal is too dry or the spring is too tight.

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Type of needle bearing

Type of needle bearing:

In addition to the catalogue, it can be used for general engineering bearings, such as: open drawn cup needle roller bearings (1), closed cup needle roller bearings (2), needle roller bearings with inner ring (3) and Inner ring needle roller bearings (4) SKF can also supply various types of needle roller bearings, 1, needle roller cage assembly 2, non-ribbed needle roller bearings 3, self-aligning needle roller bearings 4, combined needle roller / ball Bearing 5, combined needle roller / thrust ball bearing 6, combined needle roller / cylindrical roller thrust bearing

Drawn cup needle roller bearings

The drawn cup needle roller bearings are needle bearings with a thin stamped outer ring. Its main features are low cross-section height and high load carrying capacity. Mainly used for bearing arrangements that are compact, inexpensive, and the bore of the bearing housing cannot be used as the raceway for the needle roller cage assembly. The bearing and bearing housing must be installed in an interference fit. If the axial positioning function such as the box shoulder and the stop ring can be omitted, the inner hole of the bearing housing can be made extremely simple and economical.

The drawn cup needle roller bearings mounted on the shaft end are open on both sides (1) and closed on one side (2). The base end face of the closed stamped outer ring can withstand small axial guiding forces.

Drawn cup needle roller bearings generally do not have an inner ring. In the case where the journal cannot be hardened and ground, the inner ring listed in the table can be used.

The hardened steel outer ring of the drawn cup needle roller bearing is inseparable from the needle roller cage assembly. The free space to store the lubricant can extend the relubrication interval. Bearings are generally designed in a single row. Except for the wider series of bearings 1522, 1622, 2030, 2538 and 3038, they are equipped with two needle retainer assemblies. The outer ring of the bearing has a lubrication hole. All single row drawn cup needle roller bearings with a shaft diameter greater than or equal to 7 mm can be equipped with an outer ring with a lubrication hole (code suffix AS1), depending on the user's needs.

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Problems that should be paid attention to when using variable speed INA self-aligning ball bearings

1. Understand the shape and connection dimensions of the variable speed drive INA self-aligning ball bearing.
2. Variable speed drive INA self-aligning ball bearings can be placed horizontally or vertically or tilted. Can be rotated forward and backward. Positive and negative input and output power.
3, variable speed drive INA self-aligning ball bearings regardless of the installation method, and its couplings have size requirements.
Recommended:
The inner ring hole d and the shaft are matched by H7/h6;
The pin hole do of the middle ring and the transmission are matched by H7/r6;
The outer ring D and the housing are matched by H8/h7;
The gear is matched with the hole on the output shaft by a clearance fit, and the gap is 0.2~0.5mm.
4. Axial positioning of the variable speed drive INA self-aligning ball bearing: After any three turns of the ring are axially positioned, the other two axes do not need to be axially positioned.
5. Positioning in the direction of rotation; both the outer ring and the inner ring are flat key positions. The middle circle is positioned by the drive.
6. Variable speed drive INA self-aligning ball bearings can withstand small external forces in the radial direction, but should not withstand large working loads.
7. Transmission ratio is the transmission ratio according to the first installation method. If other installation methods are used, the gear ratio should be calculated.
8. At the rated speed (1500 rpm), select the variable speed drive INA self-aligning ball bearing model according to the transmission ratio and the required power (Kw).
9. When based on the working torque, the model number should be selected accordingly.
10. The selection of the reducer model should be consistent with the model of the variable speed drive INA self-aligning ball bearing.

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Vibration and temperature check of SKF needle roller bearings in operation

SKF needle roller bearings are sensitive to bearing damage. For example, peeling, indentation, rust, cracks, wear, etc. are reflected in the bearing vibration measurement. Therefore, by using a special SKF needle bearing vibration measuring device (frequency analyzer) Etc.) The magnitude of the vibration can be measured, and the specific situation of the abnormality cannot be inferred by the frequency division. The measured values ​​vary depending on the conditions of use of the bearing or the mounting position of the sensor. Therefore, it is necessary to analyze and compare the measured values ​​of each machine in advance to determine the judgment standard.
Second, the temperature of SKF needle roller bearings
The temperature of the SKF needle roller bearing is generally estimated by the temperature outside the bearing. If the oil hole can directly measure the outer ring temperature of the SKF needle bearing, it is more suitable.
Normally, the temperature of the SKF needle roller bearing rises slowly as the bearing starts to run, and reaches a steady state after 1-2 hours. The normal temperature of SKF needle roller bearings varies with the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are suitable, the SKF needle roller bearing temperature will rise sharply and abnormal temperature will occur. At this time, it is necessary to stop the operation and take necessary precautions.
The thermal sensor can be used to monitor the working temperature of the SKF needle roller bearing at any time, and automatically alarm or stop the occurrence of the burning shaft accident when the temperature exceeds the specified value.
The high temperature often indicates that the SKF needle roller bearing is in an abnormal condition. High temperatures are also harmful to the lubricant of the bearing. Sometimes bearing overheating can be attributed to the lubricant of SKF needle roller bearings. If the bearing is rotated for a long time at a temperature exceeding 125 °C, the life of the SKF needle bearing will be reduced. Causes of high temperature bearings include: insufficient lubrication or excessive lubrication, lubricants. Contains impurities, excessive load, bearing damage, insufficient clearance, and high friction caused by oil seals.

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INA imported bearings damage regular maintenance measures

Rolling bearings, if there is no choice of mistakes can be used correctly, can be used for a long time before the life of INA bearings, in this case, the damage state is peeling.
On the other hand, there are accidental early damage, and early damage that cannot be used, as the cause of the early damage, there is insufficient consideration of the use of scare lubrication, and further foreign matter intrusion, error and shaft of INA imported bearing assembly The deflection is large, and the research on the shaft and the bearing housing is not enough. It can be said that these reasons overlap with each other.
Therefore, in order to fully understand the machine used in the bearing, the conditions of use, and the structure of the outer ring of the INA bearing, if the situation before and after the accident can be clarified, combined with the damage of the bearing and various reasons, it can be prevented. The same kind of accident happened again.
The equipment is inspected regularly, the operation inspection and the bearings removed during the replacement of the peripheral parts are inspected, and the second time is judged whether it can be used again or the use condition is better or worse. The bearings and appearance of the INA bearings that have been removed should be carefully investigated and recorded. In order to clarify and investigate the remaining amount of lubricant, the bearings should be cleaned well after sampling.
Next, check the condition of the raceway surface, the rolling surface and the mating surface, and the wear state of the cage, etc., for damage and abnormality.
Judging whether INA imported bearings can be used again, it is necessary to consider the degree of bearing damage, machine performance, importance, operating conditions, inspection cycle, etc. If the bearing is found to be damaged or abnormal, the contents of the injury section will be identified and the countermeasures will be developed. In addition, the inspection results, if there are the following defects, the bearings can no longer be used, need to replace the new INA bearings.
a. Cracks and fragments appear in any of the inner and outer rings, rolling elements, and cages.
b. Any one of the inner and outer rings and the rolling elements are peeled off.
c. The raceway surface, ribs, and rolling elements are significantly khocked.
d. The cage is worn out or the rivets are loose.
e. The raceway surface, rolling elements are rusted and flawed.
f. There are significant indentations and marks on the rolling surface and rolling elements.
g. Creep on the inner diameter of the inner ring or the outer diameter of the outer ring.
h. Superheated and discolored.
i. Grease seal bearing seals and dust caps are damaged.

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