Low vibration bearing applications

Low vibration bearing applications

    1 Vibration from the bearing by the production error 

Inner and outer ring raceway and the rolling surface of the rolling bearing in the circumferential direction have different degrees of wavy machining marks - waviness, it is extremely important factors bearing vibration and noise induced by the rotation axis of the shaft occurred Imperative eccentric motion . Since the vibration waviness formed by machining marks caused, no radial clearance for bearings or axial load is applied, among other bearings Ball bearings inside out will occur, in addition to the raceway waviness of the wave number many bearings when subjected to radial load will occur.

Due to the above-described rolling bearing surface waviness caused by manufacturing considerations, wish to control its impact on bearing vibration, and only by improving the rolling surface machining accuracy and reduce the raceway surface shape error to be resolved. Modern level of technology, which has made progress, but not completely eliminate a major source of the vibration and noise. It should be noted not only factor bearing manufacture, and installation of the factors and conditions rigid bearing shaft and housing, are likely to make the raceway surface of the bearing to produce waviness, their impact is often greater than the impact of manufacturing considerations, it is bearing users must address the issue.

2 in the shaft and housing bore shape and position accuracy

Bad shape and position accuracy of the shaft and housing bore, after its bearing mounting ring deflection occurs, the vibration caused by low-frequency vibration so than natural rolling bearing surface waviness caused bigger.

2.1. Effect of the mounting surface geometric errors

Bearing raceway roundness 2μm generally about mounting surface shape error is greater than 2μm- generally having from 2 to 10 waves waviness, when the bearing ring with interference fit onto this surface, raceway there may be 2 to 10 conform waviness, while higher than the operating speed of 2 to 10 times the vibration occurs.

If there is a tight fit or splines and keys near the journal bearing is installed, it may lead to bearing raceways waviness appears. The mounting surface in the axial direction or not straight abutments chamfer radius is too large, it will have a similar ferrule similar vibration and noise caused by the deformation. Therefore, as in the mounting surface inspection found that the above situation, the need for repair or replacement by desirable to match the quality of the parts.

2.2 ferrule and positioning abutments are not perpendicular impact

When locating bearing ring and install parts of the shoulder block is not vertical, as it is moving in the circumferential direction of fit, distorting the ring, the raceway becomes oval, its roundness error about the gap between the collar and the mounting surface twice.

2.3 Effect of excessive clamping force

Practice has proved that the outer deformation easily susceptible to excessive clamping force. The outer ring and housing bore is generally clearance fit, with two end caps axial positioning and clamping to prevent fretting abrasion. When the cover is too thin, the shape and position error, the clamping force is too large, or the clamping force of the bolts uneven outer ring will have a great distortion. Since the clamping ring distortion caused by large deformation, vibration and noise caused also significant, we must ensure that the required accuracy of the end cap, uniform and moderately tighten the bolts to reduce the deformation of the outer ring due to the clamp.

2.4 with the bearing mounting surface too loose

Bearing mounting surface with too loose, in case of a rotating ring and the mounting surface (usually axis) between the ferrule with respect to the radial movement of the mounting surface may occur, thus changing the balance, centrifugal force excitation occurs elastic vibration, axial clamping even be, but still rings in the thermal expansion of "creep" mode tends to radial imbalance.

If the fixed ring with the mounting surface (usually a housing bore) between too loose, the weight of the shaft system would make it easier for ring deformation, the emergence of various roundness, axial clamping them if such modification would aggravated and fixed down, when the bearing on the operation of this modification of the elastic vibration excitation. In addition, if mating surface between the outer ring and housing bore is too loose, it is easy to obtain a large bearing clearance, - that will increase the alternating elastic vibration. Therefore, to avoid such vibration occurs, the bearing can not fit too loose.

2.5 Effect of the coaxial error

Geometric deviation concentricity error and the rolling surface of the bearing, shaft and housing bore concentricity and vertical degree and its related shoulder block, but usually the latter dominated, bearing itself relative error is much smaller. For ball bearings, concentricity error affect their basic rotation error significantly and thereby generate vibration and rotational speed related.