Analysis of other factors that aggravate fretting wear
* : * : admin * : 2023-03-15 * : 13
3. Analysis of other factors that aggravate fretting wear
3.1 There is no relative rotation between the needle roller and the inner and outer raceways
The fretting wear trace of the needle bearing is usually the equidistant indentation (as shown in Figure 2). This is because when the transmission is running in the upper gear, the needle, the gear inner hole and the shaft rotate together, the needle does not rotate, and the needle does not rotate relative to the gear inner hole and the outer diameter of the shaft. At this time, the relative position of the needle roller and the circumferential direction of the gear inner hole or the outer diameter of the shaft remains unchanged, and only the axial reciprocating movement occurs, so the equidistant indentation occurs. Through the method of opening the needle roller bearing cage or dividing the cage into two halves, the radial unsymmetrical force and the imbalance of gravity and centrifugal force can be realized, thus forcing the needle roller to rotate relative to the gear inner hole or the outer diameter of the shaft, and avoiding the fretting wear caused by long-term axial friction at the same position. This method is also one of the measures often used to solve the fretting wear of needle roller bearings in engineering.

3.2 Resonance with shaft vibration
Due to machining error and assembly error, the shaft itself will produce eccentric vibration during the working process. If the frequency of this vibration is the same or close to the vibration frequency of the fretting process, they are very likely to produce resonance. Once resonance occurs, the fretting wear of needle roller bearing will be significantly aggravated. By improving the straightness machining accuracy and assembly coaxiality accuracy of the shaft, the amplitude of the shaft itself can be effectively reduced, thus weakening the resonance.
The fretting wear is one of the common failure forms of needle roller bearings. Through the analysis of the fretting wear mechanism of needle roller bearings, the main influencing factors of fretting wear are found. Based on the analysis of the action principle of various influencing factors of fretting wear, several preventive measures to avoid fretting wear are proposed from the design aspect. Among these preventive measures, improving the lubrication structure to achieve full lubrication and using the open or split cage to achieve the relative rotation of the needle and the inner and outer raceways are often used and effective measures in engineering. Reducing the fretting displacement of needle roller bearings is a new measure based on the research of fretting wear mechanism, which provides a new idea for the follow-up design and the analysis and solution of market problems. With the further study of fretting wear mechanism and more engineering practice, more and better optimization measures will be found and proposed to completely avoid the occurrence of fretting wear.