The precision of the rolling bearing design

The precision of the rolling bearing design mainly includes the size of the rolling bearing manufacturing precision, position tolerances, surface roughness, etc. 1, the tolerance grade according to the basic dimension tolerance and its outer ring rolling bearing rotating accuracy is divided into five: its name and code from low to high respectively o-level/PO, senior/P6 / P6x levels, precision/P5, ultra-precision/P4 and the most sophisticated level/P2 ( GB / T272 - 1993). 。 Anyone who is a common bearing, generally not marked on the bearing type tolerance grade code ( GB307. 3 - 1984). 。 2, poor tolerance zone whatever size of male belt is decided by two factors: the tolerance band width and the position of the tolerance zone. Tolerance zone of rolling bearings is no exception, the tolerance zone is shown in figure 1. Figure 1 bearing inner diameter tolerance zone figure low bearing inner and outer diameter of the tolerance zone is characterized by: all tolerance zone are one-way offset below the zero line, the upper deviation is 0, the deviation of negative. 3, rolling bearing the basic size and tolerance of 1) Basic dimensions: refers to the basic size of rolling bearings of rolling bearing inside diameter d, diameter d and B bearing width. 2) Bearing dimension: the bearing inner and outer are based on thin-walled structure, manufacture and easy deformation, when stored in but after assembly can be correct. To facilitate the manufacture, the certain deformation is allowed. In order to ensure the bearings with the combination of a property, limited by only inner and outer ring in the average diameter of the single plane, namely with the bearing size. 3) Size manufacturing tolerance: the national standard of bearing inside diameter and outside diameter size tolerance for the two kinds of regulations, provisions of the inner and outer diameter is the size of the deviation, the maximum and the minimum allowed by the single inside and outside diameter deviation, its purpose is to limit the deformation; Second, the provisions of the inner and outer diameter of the actual size of the mean value of the maximum and the minimum deviation, the single plane average inner and outer diameter deviation, the purpose is to fit for bearings. Both should comply with the national standard. 4) The rotating precision of rolling bearings: refers to the bearing inner and outer circle of the radial run-out tolerance; Bearing inner and outer ring of the end face runout tolerance of inner hole axis. 4, bearing tolerance zone marked example: known bearing the basic dimensions as shown in figure 2. According to the actual working condition using E ( Is equivalent to/P6) Centripetal bearing, try to draw shaft bearing hole tolerance zone and mark the size. Figure 25, precision grades of rolling bearing are considered in the choice of the following: 1) Machine function rotation accuracy of bearing parts. Generally such selection: low/PO: used in common institutions of rotation accuracy is not high. Low/P6, P4 and P5: used in the institutions of high rotating accuracy is higher or speed. Low/P2: used for high precision, high speed precision components. 2) Speed of high and low: high speed, as the same as that of rotation of the bearing fit or hole may beat along with the beat of bearing, is bound to cause rotation is not smooth, vibration and noise. Therefore, high speed, should choose high precision bearings. 3) Structure choice: belongs to the category of the mechanical parts. Main shaft for force analysis, determine the type of bearing ( To the heart, thrust, the centripetal force) , bearing the basic size ( Inside diameter, outside diameter, bearing width) 。 4) Bearing with the precision of the calculation: bearing is selected according to working condition; To match the bearing of the shaft, bearing the needed precision design: including cooperate with determine the nature of, the determination of form tolerance, the determination of surface roughness, etc. This part is solved by interchangeability.