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The set sleeve is an accessory of the inner tapered hole bearing, which can ensure the stable operation of the supporting bearing and long service life. NTN bearing is the basic requirement. To achieve this goal, the set sleeve product must achieve high precision. The following four technical accuracy are important:
The national standard stipulates that the dimension section below the inner diameter of KD0 bearing with large value is about 1 / 2 of the large clearance value of the bearing standard group, which is equivalent to the large clearance value of C2 precision. Therefore, it is not feasible for the national standard qualified tightening sleeve products to be used in the matching of precision grade high load bearings.
Through the actual measurement of imported high-precision and high price tight fag bearing fixed sleeve products and the application effect in the domestic compressor industry, it is concluded that KD0 ≤ 0.005 can be called high precision and can meet the performance requirements of high-precision and large load supporting bearings. This value is about 5 to 12 times higher than the average calculation of each size section of the national standard tolerance.
The national standard is expressed by △ d1mp – △ d3mp. The allowable deviation of different size segments from + 0.018-0.09 is the upper deviation. It is required that the cone angle difference of the tightening sleeve can only be large but not small, that is, the large end must be matched and contacted, and the small end of the cone can have a little clearance. If the taper hole is not matched well, the matched self-aligning roller bearing will cause the stress condition of a single row of rollers, unstable operation, large vibration, loud noise and easy to loosen, The service life of the bearing is short, and the cone angle difference of the high-precision tightening sleeve should also be ≤ 0.005 to ensure that the mating contact area is not less than 90%.
that is, the positional tolerance of the shaped ina bearing is good, and the cylindricity accuracy is good. The national standard does not stipulate that any single section size is qualified within the tolerance range, which leads to the lax control of the straightness of the outer conical surface, especially the grinding of the outer conical surface, the straightness of the blank itself is poor, and the grinding wheel correction is poor, The straightness of the surface is very poor, and general enterprises do not have profiler inspection, so this project has great problems in the products of China’s tight sleeve industry, which seriously affects the matching accuracy and stability, and also leads to poor bearing performance.
The supporting bearing compresses the end face of the bearing inner sleeve through the axial movement of the locking nut, so as to tighten the taper between the tightening sleeve and the inner hole of the bearing, so as to fix the bearing on the rotating shaft. Therefore, the thread matching between the bearing nut and the tightening bushing must be better, which should meet the national standard requirements of ordinary threads.
To sum up, if the above four conditions are met, the other technical conditions must also meet the requirements of NSK bearing to the national standard. Only the high-precision setting sleeve and withdrawal bushing products can give full play to the performance and service life of the bearing.