Papers by Author: Long Chen

Abstract: Experiments were carried out to investigate the tribological properties of spherical plain bearings with copper grid composite liners filled PTFE under two contact pressures(40MPa,60MPa), four oscillating frequencies (1.2Hz, 1.8Hz, 2.4Hz, 3.0Hz) and two swinging conditions. With the help of SEM, EDS and Three-dimensional morphology profiler, the wear mechanism was analyzed. The results indicate the coefficients and wear depths under tilt swinging condition are higher than those of swivel swinging. While the friction temperature show the contrary trend. The research discovers that the friction temperature has a great influence on tribological properties of spherical plain bearings. The analysis demonstrates that the main wear mechanisms are the adhesive and abrasive wear under the two swinging conditions and extrusive wear exist also.

Abstract: The friction and wear behaviors of three kinds of spherical plain bearings with PTFE fabric composite liners were investigated by a high oscillating frequency and heavy load tribo-tester. Dry sliding tests were carried out at different oscillating frequencies. With the help of SEM and EDS, the differences of worn surfaces of the three spherical bearings were investigated. The results indicate that the fiber woven with PTFE effects the friction and wear characteristics of bearing, the tribological properties of bearing with Kevlar/PTFE fiber woven liner is the best in the three kinds of bearing. The abrasive wear are appeared on the surface of wore liners of bearingⅠ,while bearingⅡappeared normal wear, bearing III showed serious adhesive wear and abrasive wear.

Abstract: The friction and wear behaviors of three kinds of spherical plain bearings with PTFE woven liners were investigated by a high oscillating frequency and heavy load tribo-tester. Dry sliding tests were carried out at an oscillating frequency of 1.2Hz and four different loads. With the help of SEM and EDS, the differences of worn surfaces of the three kinds were investigated. The results indicate that the wear depth and friction temperature for the three kinds of bearings show increasing trend with the increasing of load, while the friction coefficient is the opposite. The comprehensive performance of bearing II is the best in the whole course of experiment, while the bearing III is the worst. The adhesive and abrasive wear mechanisms are appeared on the surface of liners. The quality of boning influences the tribological property of the spherical plain bearing.

Abstract: The working principle and performance characteristics of a self-made oscillation tribo-tester were introduced. Under different oscillation frequency and pressure conditions, the friction coefficient and linear wear of spherical plain bearings with polytetrafluoroethylene (PTFE) woven liner were investigated. By using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), the wear mechanism of the spherical plain bearing was analyzed. The results indicate that with the oscillation frequency increases, the friction coefficient of spherical plain bearings decreased while the wear loss increased. In the high frequency of 4.8Hz, the reduction ranges of the friction coefficient is not obvious with the contact pressure increased, but the effect of contact pressure on the wear of the spherical plain bearing is great. During the experiment, adhesive wear, abrasive wear and spalling wear took place on the surfaces of woven liners.

Abstract: Based on the information poor system theory, the grey bootstrap method is employed to estimate the uncertainty of the rolling bearing friction torque. The data series are obtained via the experimental investigation of the friction torque of the rolling bearings under the condition of different rotational speeds. And the results show that the mean of the dynamic fluctuant range (MDFR) of the friction torque increases with the rotational speed of the rolling bearing, revealing the new dynamic performance of the rolling bearing friction torque as a data series.

Abstract: The information entropy theory is applied to evaluate the uncertainty of the rolling bearing friction torque. The data series are obtained via the experimental investigation on the friction torque of the rolling bearings under the condition of different rotational speeds. And the result shows that the information entropy of the friction torque increases with the rotational speed of the rolling bearing, revealing the new dynamic performance of the rolling bearing friction torque as a data series.

Abstract: Based on the FEM and the relative software ANSYS, the analysis of slewing bearings with negative clearance was presented. In this paper, the stress distribution of slewing bearings under condition of different loads has been studied. The clearance has been changed by altering the ball diameter, thus the relationship between the contact stress of the inner/outer raceway and balls and the clearance has been received. Subsequently, compared to the calculation results based on some theoretical models from others, the reliability of the FEM can be verified

Abstract: This paper deals with fretting wear of blade bearings considering working conditions. The cause of fretting wear in blade bearing is analyzed and an improvement is proposed to evaluate the design of the bearing in the paper. Result from the test proves that the method of controlling fretting wear is satisfactory. Reference value of clearance in blade bearing can be obtained from the test result.

Abstract: The thin film can improve the surface performance of rolling bearings to reduce friction, vibration and noise and to increase the operating life of rolling bearings. This paper proposes a novel method for improving the surface performance of rolling bearings. This method is characterized by adding nanoparticles to the superfinishing liquid to form the nanofilm on the surface of the raceway by means of the special superfinishing technique. The experimental investigation proves that using this method, the fatigue life of the rolling bearing is obviously higher than that of the normal bearing. Surface topography photos of the Scanning Electron Microscope show that the thin film still exists after the fatigue test in 300 hours. Because of low cost, this method can be widely used in the production of rolling bearings.