High precision bearing setting and unloading bushing can be maximized

The fixing sleeve is an accessory of the inner cone hole bearing, which can ensure the stable operation of the supporting bearing and the longest life is the basic requirement. To achieve this goal, the fixing sleeve product must achieve high precision. The following four technical accuracy is the most important:

1.The radial runout of the outer cone of the bushing inside the hole (that is, the wall thickness difference KD0) should be high precision, otherwise the rotation shaft can not run smoothly due to the centrifugal force generated by the eccentricity, the vibration is large, the noise is large, the wall thickness difference is "0" is the ideal state. The national standard stipulates that the size segment below the maximum bearing diameter of KD0 is about 1/2 of the maximum clearance value of the bearing standard group, which is equivalent to the maximum clearance value of C2 precision. Therefore, the national standard qualified tight sleeve products are not suitable for precision bearing with large load.

Through the measurement of imported high-precision high-price tight set products, as well as the application effect in the domestic compressor industry, it is concluded that KD0≤0.005 can be called high precision, which can meet the performance requirements of high-precision large-load supporting bearings. This value is 5 times to 12 times higher than the national standard maximum tolerance of each size segment of the average calculation.

2, tight set cone Angle difference must be better

National standard with △D1mp-△d3mp said, different size segment allowance from +0.018-0.09 is the deviation requirements of the fixed set of cone Angle difference can only be large and not small, that is, the big end must be with contact, the small end of the cone can be a little clearance, the taper hole is not good, supporting the aligning roller bearing will cause a single row of roller stress condition, unstable operation, large vibration, Loud noise, easy loosening, bearing life is short, the cone Angle difference of high precision tight sleeve should also be less than 0.005, to ensure that the contact area is not less than 90%.

3.The straightness of the outer cone and the inner hole surface of the tight sleeve is better, that is, the shape and position tolerance is better, and the cylindricity accuracy is better. The national standard does not specify any single section size within the tolerance range is qualified, which is the result of the loose control of the straightness of the outer cone surface, especially the grinding of the outer cone into grinding, the blank itself is not straight, and the grinding wheel is not corrected well. Surface straightness is very poor, and general enterprises have no contour instrument inspection, so this project in our tight-fixing industry product problems are very big, seriously affect the supporting precision and stability of the matching, also causes the bearing performance is not good.

4.Screw locking performance of the set

The matching bearing is to squeeze the inner sleeve end face of the bearing through the axial movement of the locking nut to make the tightening sleeve and the inner taper of the bearing hole tighten, so as to achieve the purpose of fixing the bearing on the rotating shaft, so the bearing nut must be well matched with the screw thread of the tightening bushing, which should meet the national standard requirements of ordinary thread.

In summary, to achieve the above four conditions, the rest of the technical conditions must also meet the national standard requirements of the tight sleeve to calculate high-precision products, only high-precision tight sleeve and discharge bushing products to maximize the performance and life of the bearing.