For NTN import precision rolling bearing installation and test methods

NTN import bearings after installation in the host, such as the measurement of rolling bearing spindle radial runout, can be found that the each measured value of a certain change; Continuous measurement, can be found that after a certain number of revolution, this change will approximately duplicated. Measure for cyclic rotation accuracy degree of the change, change the approximately duplicated the revolution, on behalf of cyclic rotation accuracy 'cycle', the value of the amplitude changed in quasi cycle, is the cycle rotation accuracy is poor. Such as the proper preload on NTN bearing spindle, the higher speed step by step to near work speed, on bearing the 'break-in' effect, can improve the circulation of the spindle rotation accuracy. Measuring the size of the shaft and bearing hole, to determine with precision of the bearing, cooperate with requirements as follows: take the interference fit, inner ring on the shaft interference was 0 ~ + 4 microns ( At light load, high precision of 0) ; Outer ring and bearing hole clearance fit, the interval 0 ~ + 6 microns ( But on the free end bearing with angular contact ball bearing, still can increase the clearance) ; Shaft and hole surface roundness error in under 2 microns, bearing the face of baffle used parallelism in under 2 microns, shaft shoulder end foreign face beat in under 2 microns; Axis bearing hole block shoulder to beat under 4 microns; Spindle axis inside the front cover end face beat under 4 microns. Fixed end NTN import bearings on the shaft before installation: will the kerosene used to clean the bearing with clean thoroughly clean, for grease lubrication, the first containing 3% ~ 5% of organic solvent injection bearing grease for degreasing, cleaning and quantitative grease oil gun will fill in the bearing inner ( Accounts for 10% ~ 15%) of the bearing space volume ; Heat bearing the heat up 20 ~ 30 ℃, using hydraulic press the bearing into shaft end; Will set casing pressure on the shaft and with appropriate pressure against bearing face makes its axial positioning; The lace will spring balance volume on the bearing outer ring, use the method of measuring start torque check is the preload of the regulation for substantial changes ( Even if the bearing is correct, but due to cooperate or cage, the deformation of the preload is also has the potential to change) 。 Will import bearings - Shaft assembly into the hole: heating holes make up 20 ~ 30 ℃, with a continuous gentle pressure of bearing - Shaft assembly into a hole; Adjust the front cover, make the front cover of fastening is 0. 02 ~ 0. 5 microns to bearing outer end face as a benchmark, the dial gauge meter resistance on shaft neck surface, will beat measuring the rotation axis, request error under 10 microns; Will be located on the shaft, dial gauge meter resistance in the back seat hole surface, the axis of rotation to measure before and after bearing hole of the alignment. Put free end bearing selectively may offset the position of the deviation, after installed on the bearing support position, offset each other as much as possible of roundness error and axiality deviation. NTN bearing inspection to be carried out under astigmatism lamp, appearance, cracks and other parts of the bearing for careful observation. 1, all kinds of machinery, such as abrasion, cut and bruised, crushed, can cause adverse bearing installation, causing partial load and stress concentration, caused by rotation precision and service life. 2, rust, black and pitting, the latter two are easy to store water and dirt of defects, most likely to develop into rust. The rust is cause the installation of non-performing, early wear and fatigue of pollution sources, serious corrosion will make the rolling bearing damaged. 3, all kinds of crack, crack, such as raw materials, forging, heat treatment of crack crack and grinding cracks, the crack in the process of bearing after operation, will become a source of stress concentration and is expanding fast, cause bearing is broken, and great influence on bearing life and job security. In fact, for important use of rolling bearings, bearing factory has been to 100% of their component parts magnetic or radiographic inspection. 4, peeling and folding, the two defects of local combined with matrix metal not firm, and its surroundings often exist in different degrees decarburization or poor phenomenon, carbon material easy caving, the indented or abrasion, on imports NTN bearing life and accuracy very unfavorable. 5, maintains a riveting or welding quality, mainly to see whether it has offset the rivet head, skew, relaxation, lack of meat, or 'double eyelid, correct the position of the welding, solder joint is too big or too small, for welding not firm or excessive cause jam phenomenon of roller.