The installation method of the motor bearing and the preparation work before installation

The environment of the motor bearing installation The bearing installation should be carried out in a dry and dust-free room as far as possible, and should be far away from metal processing or other equipment that generates metal chips and dust. When bearings must be installed in an unprotected environment (a situation often encountered in larger motor bearings), appropriate measures must be taken to protect the bearings and related components from dust or moisture contamination until the installation is complete. Preparation of the bearing Since the bearing has been rust-proofed and packaged, do not open the package before installation. In addition, the anti-rust oil coated on the bearing has good lubrication performance. For general-purpose bearings or bearings filled with grease, it can be used directly without cleaning. But for instrument bearings or bearings used for high-speed rotation, clean cleaning oil should be used to wash away the anti-rust oil. At this time, the bearing is easy to rust, so it should not be left for a long time. Preparation of installation tools The tools used during installation should be mainly wooden or light metal products, avoid using other things that are prone to debris; keep the tools clean. Inspection of shaft and housing Clean the shaft and housing to confirm that there are no scars or burrs left by machining. If any, use oil stone or fine sandpaper to remove. Abrasives (SiC, Al2O3, etc.) molding sand, cutting chips, etc. must never be inside the shell. Secondly, check whether the size, shape and processing quality of the shaft and the housing conform to the drawings. As shown in Figure 1 and Figure 2, measure the shaft diameter and housing bore at several locations. Also carefully inspect the fillet size of the bearing and the housing and the verticality of the shoulder. In order to make it easier to assemble the bearing and reduce the impact, before installing the bearing, the mating surfaces of the shaft and the housing that have passed the inspection should be coated with mechanical oil. Classification of bearing installation methods The installation method of bearings differs depending on the bearing type and matching conditions. Since generally shaft rotation is used, the inner ring and outer ring can adopt interference fit and clearance fit respectively, and when the outer ring rotates, the outer ring adopts interference fit. When adopting interference fit, the bearing installation methods can be divided into the following types, as shown in the figure below. The most general method is to install the bearing after cooling it with dry ice. At this time, the moisture in the air will condense on the bearing, so it is necessary to take appropriate anti-rust measures. Outer ring interference fit press installation, cold shrink installation, press installation, suitable for the installation of hot sleeves of NMB miniature bearings with low interference Suitable for bearings with large interference or large bearing inner rings with interference fit. Bearings with tapered bores are installed on tapered shafts with sleeves. Cylindrical bore bearings. Cylindrical bore bearings. Press-in installation. Press-in installation generally uses a press or bolts. With nuts, a hand hammer can be used to install when necessary. When the bearing is installed on the shaft with an interference fit of the inner ring, pressure must be applied to the inner ring of the bearing; when the bearing is installed on the outer ring with an interference fit of the outer ring, pressure must be applied to the outer ring of the bearing; When the rings are interference fit, a backing plate should be used to ensure that the pressure can be applied to the inner and outer rings of the bearing at the same time. The hot-sleeve installation heats the bearing, expands it and then installs it on the shaft. The hot-sleeve method can avoid unnecessary external force on the bearing and complete the installation in a short time. There are two main heating methods: oil bath heating and electric induction heating. The advantages of electric induction heating: 1) Clean and pollution-free; 2) Timing and constant temperature; 3) Simple operation. After the bearing is heated to the desired temperature (below 120°C), take the bearing out and quickly put it on the shaft. The bearing will shrink as it cools. Sometimes there will be a gap between the shaft shoulder and the end face of the bearing. Therefore, you need to use tools to The bearing is pressed towards the shoulder. When installing the outer ring with an interference fit to install the outer ring on the bearing box, for small bearings, the outer ring can be pressed in at room temperature. When the interference is large, press in by heating the bearing box or cooling the outer ring. When dry ice or other coolants are used, the moisture in the air will condense on the bearings, and corresponding anti-rust measures must be taken. Bearings with dust cover or sealing ring, because the pre-filled grease or sealing ring material has a certain temperature limit, the heating temperature should not exceed 80 ℃, and the oil bath heating method cannot be used. When heating the bearing, it should be ensured that the bearing is heated evenly and will not cause local overheating.