Before installing bearings, they should be cleaned with gasoline or kerosene, dried before use, and well lubricated. Bearings are generally lubricated with grease or oil. When using grease lubrication, lubricating grease with superior properties such as impurity free, antioxidant, rust proof, and extreme pressure should be selected. The filling amount of lubricating grease should be 30% -60% of the volume of cylindrical roller bearings and bearing boxes, and should not be too much. The double row cylindrical roller bearing with sealing structure and the water pump shaft connecting bearing have been filled with lubricating grease, and can be used directly by users and cannot be cleaned again.
When installing bearings, equal pressure must be applied on the circumference of the ring end face to press the ring in. It is not allowed to directly hit the bearing end face with tools such as a hammer to avoid damaging the bearing. In the case of small interference, a sleeve can be used to press the end face of the bearing ring at room temperature, and a hammer can be used to strike the sleeve. The ring can be evenly pressed in through the sleeve. If installed in large quantities, hydraulic presses can be used. When pressing in, it should be ensured that the outer ring end face is tightly pressed against the outer shell shoulder end face, and the inner ring end face is tightly pressed against the shaft shoulder end face without any gap. The installation of bearings must be carried out under dry and clean environmental conditions. Before installation, the mating surface of the shaft and casing, the end face of the shoulder, the groove, and the machining quality of the connecting surface should be carefully checked. All mating connection surfaces must be carefully cleaned and deburred, and the unprocessed surface of the casting must be cleaned of molding sand. When the interference is large, oil bath heating or inductor heating of the bearing can be used for installation. The heating temperature range is 80 ℃ -100 ℃, and the high temperature cannot exceed 120 ℃. At the same time, nuts or other appropriate methods should be used to tighten the bearings to prevent the width contraction of the bearings after cooling, resulting in a gap between the collar and the shaft shoulder.
After the installation of the bearing, the clearance should be adjusted. The clearance value should be determined specifically based on different operating conditions and the size of the interference fit. If necessary, experiments should be conducted to determine. The clearance of the double row cylindrical roller bearing and the water pump shaft connecting bearing has been adjusted at the factory, and there is no need to adjust them during installation. After the installation of bearings, a rotation test should be conducted. Firstly, it should be used to rotate the shaft or bearing box. If there are no abnormalities, power should be used for no-load and low-speed operation. Then, the rotation speed and load should be gradually increased according to the operation situation, and noise, vibration, and temperature rise should be detected. If any abnormalities are found, the operation should be stopped and checked. Only after the operation test is normal can it be delivered for use. Contact fatigue failure is one of the common failure modes of various imported bearings, which is caused by the repeated action of cyclic contact stress on the surface of imported bearings. The contact fatigue spalling on the surface of bearing parts is a process of fatigue crack initiation, propagation, and propagation. The initial contact fatigue crack first arises from the large orthogonal shear stress below the contact surface, and then extends to the surface to form pitting or small flake like spalling, the former being called pitting corrosion or pitting spalling; The latter is called shallow peeling. If the initial crack occurs in the junction area between the hardened layer and the core, causing early peeling of the hardened layer, it is called peeling of the hardened layer. It is one of the common failure modes on various bearing surfaces. The relative sliding friction between bearing parts leads to continuous loss of surface metal, which is called sliding friction loss. Continuous wear will cause changes in the size and shape of the parts, increase bearing clearance, and deteriorate the working surface morphology, resulting in a loss of rotational accuracy and the inability of cylindrical roller bearings to function properly. The forms of sliding wear can be divided into abrasive wear, adhesive wear, corrosive wear, and fretting wear, among which the common ones are abrasive wear and adhesive wear.
