Motor fixed end bearing Fixed end bearings use radial bearings capable of carrying combined (radial and axial) loads. These bearings include: deep groove ball bearings, double row or paired single row angular contact ball bearings, self-aligning ball bearings, spherical roller bearings, matched tapered roller bearings, NUP type cylindrical roller bearings or with HJ angular rings NJ type cylindrical roller bearings. For the selection of the fixed end of the motor bearing support (referred to as the fixed end of the motor), the following factors should be considered: (1) Accuracy control requirements of the dragged equipment; (2) The nature of the load driven by the motor; (3) The 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. Motor floating end bearing The floating end of the motor is also called the free end, which is relative to the fixed end; in general, the floating end is selected at the non-driving end, but the motor load requirements are relatively high, and the axial matching size requirements with the load equipment are not very high In this case, the floating terminal will be selected as the driving terminal. When the motor bearing support system is a double fulcrum and double bearing structure, when the radial load requirement is large, the driving end is also used as the floating end, especially for low-voltage, high-power and high-voltage motors, the cylindrical roller bearing at the floating end can meet the radial load requirements. higher load requirements. The rollers of cylindrical roller bearings are in line contact or trimmed line contact with the raceway, and have a large radial load capacity, which is more suitable for bearing heavy loads and impact loads. The inner ring or outer ring can be separated for easy installation and disassembly. This series of bearings has a small friction coefficient and is suitable for the operating conditions of high speed and limit speed close to deep groove ball bearings. The N-type and NU-type cylindrical roller bearings commonly used in motors can move axially between the inner and outer rings of the bearing, and can adapt to changes in the relative position of the shaft and the housing caused by thermal expansion or installation errors, and can be used as free end support. However, the bearing has high requirements on the processing of the shaft or the bearing chamber hole, and the relative deviation of the axis of the inner and outer rings after the bearing is installed must be strictly controlled to avoid contact stress concentration. Compared with the fixed end bearing, in order to meet the axial displacement requirements of the rotor part during the operation of the motor, the axial clearance requirements between the outer ring of the bearing and the inner and outer covers of the bearing are different according to the selection of the bearing. (1) When the floating end adopts a bearing with separable inner and outer rings, for a two-bearing structure motor, the fixed end is selected at the non-driving end; the outer ring of the fixed end and the floating end bearing and the inner and outer covers of the bearing are all axially free of clearance Cooperate. (2) When non-separable bearings are used at the floating end, that is, both ends of the small and medium-sized motors are relatively ball bearing structures. The ring should be limited, and there is an axial gap between the outer ring and the inner and outer cover of the bearing; at the same time, in order to ensure the axial matching displacement requirements during the operation of the motor, the radial fit between the outer ring of the bearing and the bearing chamber should not be too tight. The actual bearing configuration should match the operating conditions of the motor, including specific parameters such as clearance, heat resistance, precision, etc. in the selection of motor bearings, as well as the radial fit relationship between the bearing and the bearing chamber.