precision precision bearings

After the installation of precision precision bearings
1. Improve The Accuracy

After bearing installed in the host, as measured radially spindle runout, bearing slidably found each measurement value turn have some change; continuous composite bearing measurements can be found after a certain number of revolutions after the change It will be approximately repeated. This change is a measure of the degree of precision rotation cycle indicators, approximately repeated changes in the number of revolutions required on behalf of the rotation cycle accuracy “quasi-periodic”, the magnitude of the change in the quasi-periodic large amplitude, rotation accuracy is poor circulation .

If properly pre-load on the spindle, the speed gradually increased to the oil-bearing close to the operating speed to implement bearing “run-in” effect, can improve the accuracy of spindle rotation cycle.

2. One way to improve the accuracy of bearing

Factory trial precision instruments, spindle 6202 / P2 type bearings and its accuracy still can not meet the requirements, after making the bold and the journal in which the raceway to replace the inner ring, steel ball and waxy Density Measurement to size every three groups, each taking the ball closer spacing of 120 ° apart, due to the reduction of a heavy machined surface, but also reduce the weight of a mating surface, while improving the rigidity of the shaft-bearing system, and the maximum and minimum three three close grain balls equally spaced, and improve the accuracy of the rotation axis, so the instrument meets the accuracy requirements.

3. Install accuracy Comprehensive Verification Method

After the angular contact ball bearings into the spindle mounting accuracy of the calibration sequence is as follows (in shaft diameter is lathe 60-100mm example):

(1) measurement of the shaft and the bearing hole size to determine with precision bearings, with the following requirements:

Take the inner ring and the shaft interference fit, the amount of interference 0 ~ + 4μm (at light load, when precision is 0); take the outer ring and the bearing hole gap with the clearance amount 0 ~ + 6μm (but at the free end of the bearing when using angular contact ball bearings, but also increase the gap); the surface of the shaft and housing bore roundness error in 2μm or less parallel end surfaces of the bearing cage used in 2μm or less, the inner shaft shoulder end of the end face of foreign beating 2μm or less; retaining shoulder on the housing bore axis beating 4μm or less; cover the face of the front end of the spindle axis beating 4μm or less.

(2) fixed to the front end of the bearing mounted on the shaft

After bearing thoroughly cleaned with a clean cleaning kerosene, grease lubrication, the first containing 3% to 5% of the grease into the bearing organic solvents for degreasing, and then quantitative grease gun grease filled within the bearing (accounting bearing space volume of 10% to 15%); heating the bearing temperature elevation 20 ~ 30 ℃, hydraulic press bearing onto the shaft; the adapter sleeve bears on the shaft and a suitable pressure against the end face of the bearing are axially the spring scale tape volumes on the bearing outer ring, the pre-load starting torque measurement method prescribed check whether there is a significant change (even if the bearing is correct, but to keep fit or deformed frame, preload there; Location changes possible).

(3) bearing – axle assembly mounted seat hole

Heated seat hole so warm 20 ~ 30 ℃, with continuous gentle pressure bearing – axle assembly mounted housing bore; adjust front cover, the amount of fastening the front cover is 0.02 ~ 0.05μm, to the outer face of the bearing housing reference, dial indicator table header conflict on the journal surface, the axis of rotation measured beating error of 10μm the following requirements; dial indicator positioned on the shaft, the first table in the back seat contradict the interior surface, the axis of rotation front and rear seat to measure the bearing bore concentricity.

(4) The free end of the bearing may be selectively placed in a position offset bias, install the rear bearing support position, as much as possible to offset the roundness and concentricity deviation deviation between each other.

4. tapered bore double row cylindrical roller bearing installation

When installing NN3000K series double row tapered bore cylindrical roller bearings, we must pay attention to the inner diameter of the bearing and taper shaft fit correctly in the case of low-volume production of usable coloring contact method validation, but in the production of large quantities , preferably with a precision taper gauge check.

In the bearing mounted on a tapered shaft, the inner ring should be transferred to the appropriate position in the axial direction, so that the radial clearance close to zero.