Installation instructions for precision bearings

I Abstract: (1) the roundness of the shaft and hole and vertical shoulder according to the corresponding precision bearings to requirements. To guarantee the higher actual tie effect, shaft and hole matched with a bearing surface, the roughness should be as small as possible. On the surface with implementation of surface strengthening measures such as sandblasting, precision plunger slightly larger diameter plug a hole, it is beneficial to improve the matching accuracy.

1. requirements of precision bearings for matching parts

Because of the precision of precision bearings within 1 m, so the matched parts (shaft, bearing, end cover, ring etc.) have very high dimensional accuracy and shape accuracy, especially fitting accuracy should be controlled in the same level and bearing, it is extremely important, but also the most easily neglected.

We must also pay attention to match parts of precision bearings if not up to the above requirements, often make precise bearing times bigger than the error occurred in the original bearing after installation, even more than 10 times the error, completely not the precision bearings, the reason is the error matching parts are often not simply superposed on the bearing, but by the different magnification after added.

2. coordination of precision bearings

In order to ensure that the bearing does not produce too much deformation after installation, it must be done:

(1) the roundness of the shaft and the seat hole and the verticality of the shoulder should be in accordance with the relative accuracy of the bearing.

(2) it is necessary to accurately calculate the interference fit of the rotating rings, and also to accurately calculate the proper fit of the fixed rings.

The rotating ring of burning of interference within the possible range should be made smaller. As long as the guarantee of working temperature under the influence of thermal expansion, and the highest speed under the influence of centrifugal force, without causing tight fit creeping or sliding on the surface. The fixed rings depending on load size and bearing size, or with minimal clearance extraction fit, too loose or too tight is not conducive to precise shape.

(3) bearing such as running under the condition of high speed and high working temperature, should pay special attention to the support of rotating rings can not be too loose, to prevent vibration of eccentric, and with the fixed ring can not appear the gap, to prevent the ring distortion under load and vibration excitation.

(4) to take the fixed ring with little surplus condition is matched both have very high surface shape accuracy and smaller roughness, otherwise difficult to install and remove the cause is more difficult, in addition, also need to consider the influence of spindle thermal elongation.

(5) the use of duplex angular contact ball bearings, bearing a much lighter, with the amount of interference such as too large, its internal axial preload will be significantly larger, causing adverse effects. The use of double row cylindrical roller bearing, tapered roller bearing spindle spindle, the load relatively large, so the interference is relatively large.

3., improve the actual matching accuracy method

In order to improve the actual bearing fit precision during installation, must use the measurement methods and tools do not make the bearing deformation, precision measurement of the bearing inner hole and the outer circle with the surface of the actual size, the measurement items related to the inner and outer diameters of all be measured, and made a comprehensive Analysis on the measured data, the according to the bearing precision matching shaft and hole mounting parts size. The distribution of shaft and hole in the actual measurement of the corresponding size and geometry, should be carried out in temperature conditions and measurement of bearing under the same.

The roughness of the shaft and seat bore to the bearing shall be as small as possible in order to ensure a high practical fit.

In the measurement, should be in the outer circle and the inner hole of the bearing, and the corresponding surface of shaft and hole on both sides in the near assembly chamfer, respectively to two groups can show the maximum deviation direction mark, so that in the actual assembly, so that the maximum deviation match two party at the same position. In this assembly, both of deviation to partially offset.

Make two sets of directional signs, is the deviation compensation can be considered, their rotational accuracy even supported at both ends has increased, and between the two bearing seat hole and trunnion coaxiality error on both ends are partially eliminated. On the surface with the introduction of surface hardening measures, such as sandblasting, precision plunger diameter the plug a hole, it is beneficial to improve the matching accuracy.