The working environment and the performance of the miniature ball bearings

The miniature ball bearings is composed of an inner, outer ring, rolling body (ball, roller or needle roller and cage) is composed of four parts, in addition to maintain the reactor, the rest are composed of bearing steel. When the bearings, bearing inner, outer ring, rolling bearing body bear the high frequency, stress function. Bearing working conditions are very complicated. Load concentration in a small area of the rolling body. Theory for the ball, in a point; and the roller is in a line, and the rolling body and the ring contact area is very small (a point / line contact), so the bearing parts in the work, the rolling body and the ring surface per unit area to bear great pressure in general, up to 1500 - 5000N/mm2; Series radial ball bearings rotation, but also bear the role of centrifugal force, the force increases as the speed increases; a rolling body and a ferrule exists not only rolling, and sliding, so there is friction between the roller and ring. The comprehensive role in the above several stress, fatigue strength of low position on the surface of ring or rolling of the first fatigue crack, finally forms the fatigue spalling, the bearing failure. Bearing normal damage form is the contact fatigue damage, common and plastic deformation, indentation, wear, cracks etc.

Check the flanged ball bearing quality of four points

First, turn tone with a stethoscope to check flanged ball bearing, a metallic noise, strong noise, irregular, abnormal sound. Due to poor lubrication, shaft or housing poor accuracy, bearing damage, foreign intrusion etc..

Second, the bearing temperature, generally according to the external temperature of the bearing seat to speculate. But the direct measurement of the bearing outer ring with oil hole temperature more accurately. Thrust Ball Bearings temperature, from a running start rising, usually 1~2 hours after the temperature stability. Bad if the bearings are mounted, the temperature will rise sharply, abnormal high temperature. The reason such as excessive lubricant, the self aligning ball bearing clearance is too small, poor installation, sealing device too much friction. High speed rotating occasions, lubrication structure, choice is also the cause of the error.
Guide roller, guide, slider, linear bearings, miniature ball bearings series of deep groove ball bearing series needle roller (roller) bearings, thrust ball bearings

Third, small machinery can be rotated by hand, to confirm whether the rotation is smooth. Check the project caused by foreign body, scars, indentation running sluggish, due to poor installation, mounting process arising out of the bad moment is not stable, because the clearance is too small, installation error, sealing caused by friction force is too large and so on. If there is no anomaly can begin power operation.

Fourth, large machinery can not be manually rotated, so the no-load starting immediately after power cut, mechanical idling, check whether the vibration, noise, rotating parts are in contact and so on, confirmed no abnormal, into the dynamic operation.

Double row ball slewing bearingand shaft installation inspection method

In general, tight interference fit the installation of double row ball slewing bearing must be close to the shaft shoulder. Test method: (1) the light method. The lamp alignment Koyo bearings and shaft shoulder, see the leakage judgment. If no leakage, installation is correct; if the light evenly along the shaft shoulder around, the bearing and shaft shoulder is not close, with the pressure bearing close; if partial leakage, the bearing installation tilt, can be hand hammer, brass or percussion bearing inner ring sleeve, is slowly. (2) to test the feeler gauge. Feeler gauge thickness shall be 0. 03mm began. Test, test in several in the bearing inner ring end face and shoulder the entire circumference, if there is a gap and very uniform, indicating that miniature ball bearings is not installed in place to deal with bearing, double row self-aligning ball bearing inner ring of pressure it tightly against the shoulder; if the increased pressure is not tight, the Journal fillet positions fillet is too large, the bearing is stuck, should be trimmed journal fillet, make its become smaller; if it is found that the end surface of the inner ring and the bearing shoulder thickness gauge individual parts can pass, not at this time must be removed, to be repaired, re install.

The principle of  lubricating bearings and three row roller slewing bearing are basically the same, only the bearing working condition is bad, its performance can achieve effective lubrication depends to a large extent on the bearing.‍

Tapered roller bearings and high speed bearing installation

Bearings must be installed in a dry, clean environment conditions. Before installation should check carefully with the axis and the shell surface, convex shoulder end, grooves and connecting surface processing quality. All mating surfaces connected, must be carefully cleaned and remove the burrs, not casting surface must except sand net residual.

Bearing installation should be preceded with petrol or kerosene to clean, dry after use, and ensure good lubrication, bearing the general use of grease, oil lubrication can be applied. With grease lubrication, should be used without impurities, oxidation, rust, extreme pressure properties of high quality lubricating grease. Amount of grease filled bearings and mobile crane bearing  box volume of 30%-60%, not too much. With grease has been filled with good sealing structure of double row tapered roller bearings and water pump bearings, users can directly use, no further cleaning.

Bearing installation, must be applied equally in the circumference of ferrule end face pressure, will press into the ring, not directly strike the bearing end face want first tool, so as not to damage the bearing. Small amount of interference in the case, can suppress at room temperature with the sleeve bearing ring face, beating with a hammer sleeve, through the sleeve will be pressed into the ring balance. If the high-volume installation,high speed bearing use of hydraulic machine. Indentation, should ensure the outer end face and shoulder shell surface, the inner end face and shoulder axis end pressing, does not allow a gap.

When the amount of interference is large, can be installed using oil bath heating or inductor heating method of bearing, the heating temperature range of 80 ℃ -100 ℃, the maximum should not exceed 120 ℃. At the same time, the application of nuts or other fastening bearing appropriate methods to prevent the bearing cooling, the width direction of contraction and between the ring and a shaft shoulder generation gap.

Single row tapered roller bearing installation of the final clearance should be adjusted. Clearance value should be used according to different conditions and with the amount of interference to determine the size and specific. When necessary, should be tested to determine. Double row tapered roller bearings and water pump bearing factory has adjusted well clearance, no further adjustment during installation.

Bearings should be installed after the rotation test, first hand rotation shaft or bearing box, without exception, they have no power to load, low speed operation, and then gradually increase as the functioning of the rotation speed and load, and to detect noise, vibration and temperature, abnormal, should stop and check. Test normal operation before delivery.‍

mounting of flanged ball bearing

The flanged ball bearing ‍is bearing the rotating spindle and shaft parts, which bear radial or axial load, and the load transfer to the bearing seat, the bearing seat fixed in the frame or support.

The bearing classification bearings into plain and rolling element bearings two categories. 

1.sliding bearing. By the integral bearing seat and the shaft sleeve or split bearing seat and the bearing. Sliding bearing according to the loading direction is divided into radial bearing, thrust bearing and a radial thrust bearing; according to the lubrication state of friction surface is not entirely lubricating bearings (the lubricating grease, oil or oil lubrication of the general sliding bearing, bearing, nylon bearing) and liquid lubrication bearing (hydraulic friction bearing). 

2.Rolling bearing. The outer ring, inner ring, rolling body and holder, fixed in the shell hole machine or to open the bearing seat. Rolling bearings according to the loading direction is divided into radial bearing, thrust bearing and thrust bearing.

General assembly sliding bearing comprises a sliding bearing, bearing, nylon bearing assembly method, check the bearing clearance, bearing the pressing force adjustment. Fluid friction bearing assembly saw mill installation.‍

Effect of temperature on bearing life

Bearing in the work,self aligning bearings its size may be changed by changing the structure of the material. This transformation was affected by temperature, time and stress.

In order to avoid the dimensional change not allowed due to changes in material structure in the work, bearing materials must go through a special heat treatment.

According to the different types of bearings, bearing in standard harden ability and induction quenching heat treatment of steel, the recommended maximum working temperature is between 120 to 200 degrees. There is a direct relationship betweenthe maximum operating temperature and the heat treatment process can be achieved.agricultural bearings If the normal working temperature higher than the highest temperature of someapplication suggestions, bearing should choose stable series high. If the bearing of continuous working in high temperature, load capacity of the bearing may need tomake adjustments.

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Influence of bearing structure on the vibration and noise(two).

4 holder of sound

Keep the free vibration of frame and the rolling body or ring phase impact will send this noise in the bearings rotate process. It may appear in all kinds of bearing, but itssound pressure level is not too high and the low frequency. Full complement cylindrical roller bearing Its characteristic is:

A. stamping cage and plastic holder can be generated

B. either oil or grease will appear.

C. when the outer ring bearing the bending moment is most likely to occur.

D. radial clearance large easily.

Because the cage pocket clearance and the holder and the ring gap is inevitable in bearing product to exist, self aligning bearing

‍thus completely eliminate cage sound is very difficult, but can reduce the assembly error, gap optimum and cage movement to improve.

Another cage special sound is due to the holder and the other bearing parts leading between the rubbing surfaces caused maintain self-excited vibration and noise frame.Stamping of deep groove ball bearing retainer is thin, curved in the radial and axial in-plane stiffness is low, the overall stability is poor, will the bearings rotate at high speed due to bending deformation caused by self-excited vibration, "beep".

When the bearing under a radial load and oil poor performance situation, at the beginning of operation "Kacha, Kacha hear noise", which is mainly due to the rolling body left in the load zone, noise suddenly accelerated and cage collision by rolling,the sound of impact can not be avoided but with running for a period of time will disappear.

To prevent the holder noise measures are as follows:

A. cage revolution motion stability, should as far as possible by the ring guide way and pay attention to guide the full lubrication, give the improvement of bearing structure of high speed conditions, the L type roller guide holder is changed to Z type ring ribguide holder.

B. bearings rotate at high speed, bearing pocket clearance of the cage vibration amplitude is much larger than the pocket hole cage vibration amplitude gap is small,so the pocket clearance value is very important.

C. should pay attention to reduce the radial clearance.

D. try to improve manufacturing precision frame maintain, improve the surface quality of the holder, helps to reduce body roll and keep the noise frame collision or friction.

E. actively adopt advanced cleaning technology, cleaning effective parts and the setof products, improving the cleanliness of bearing.

5 by rolling vibration

When the operation of the bearing under a radial load, its internal only a plurality ofrolling load, due to the ferrule elastic contact constitute the "spring" supporting therolling body in the radial load line generates periodic oscillation, and the shaft centerwill therefore vertically moving or moving horizontally, and causes noise. This kind of vibration is called rolling through the vibration, especially in low speed when the more obvious.

And the amplitude is related to bearing type, radial load, radial clearance and ballnumber. Usually the smaller amplitude, if the amplitude is large when the harm, this is often the minish preload appropriate axial clearance or to reduce.‍