For the selection of the fixed end of the motor bearing support (referred to as the fixed ), the following factors should be considered: (1) The precision control requirements of the driven equipment; (2) The load nature of the motor drive; (3) Bearing or bearing combination Must be able to withstand a certain axial force. Combining the design elements of the above three aspects, in small and medium-sized motors, deep groove ball bearings are more often used as the first choice for motor fixed end bearings.
Deep groove ball bearings are the most commonly used rolling bearings. When using deep groove ball bearings, the structure of the motor bearing support system is very simple, and the maintenance is also convenient. Deep groove ball bearings are mainly used to bear radial loads, but when the radial clearance of the bearings is increased, they have the characteristics of angular contact ball bearings and can bear combined radial and axial loads; thrust balls are not suitable for high speeds When used as a bearing, it can also be used to bear pure axial load. Compared with other types of bearings with the same specifications and dimensions as deep groove ball bearings, this type of bearing has the advantages of small friction coefficient and high limit speed, but the disadvantage is that it is not resistant to impact and is not suitable for heavy loads.
After the deep groove ball bearing is installed on the shaft, within the range of the axial clearance of the bearing, the radial fit of the shaft or the housing in both directions can be limited. In the radial direction, the bearing and the shaft adopt an interference fit, and the bearing and the end cover bearing chamber or shell adopt a small interference fit. The ultimate goal of choosing this fit is to ensure that the working clearance of the bearing is zero or slightly during the operation of the motor. Negative, so the running performance of the bearing is better. In the axial direction, the axial cooperation between the locating bearing and the associated parts should be determined in combination with the specific conditions of the non-locating bearing system. The inner ring of the bearing is limited by the bearing position limit step (shaft shoulder) on the shaft and the bearing retaining ring, and the outer ring of the bearing is controlled by the tolerance of the bearing and the bearing chamber, the height of the notch of the inner and outer covers of the bearing, and the length of the bearing chamber.
(1) When the floating end chooses a separable bearing with inner and outer rings, the outer rings of the bearings at both ends adopt axial clearance-free fit.
(2) When the non-separable bearing is selected for the floating end, a certain length of axial clearance is reserved between the outer ring of the bearing and the seam of the bearing cover, and the fit between the outer ring and the bearing chamber is not easy to be too tight.
(3) When the motor has no clear positioning end and floating end, deep groove ball bearings are generally used at both ends, and the cooperation relationship between the outer ring of the limit bearing and the inner cover is stuck, and there is an axial gap between the outer cover and the outer cover; Or there is no axial clearance between the outer ring of the bearing at both ends and the outer cover of the bearing, and there is an axial clearance between the inner cover and the inner cover.
The above matching relationship is a relatively reasonable relationship based on theoretical analysis. The actual bearing configuration should match the operating conditions of the motor, including specific parameters such as clearance, heat resistance, and accuracy in the selection of motor bearings, as well as bearings. The radial fit relationship with the bearing chamber, etc.
It should be noted that the above analysis is only for horizontally installed motors, but for vertically installed motors, there must be specific requirements in terms of the selection of bearings and the related matching relationship.
Post time: Mar-15-2023