Purpose The purpose of this paper is to develop an energy-efficient and dynamically improved thrust ball bearing using textured race. A texture has been used on the stationary race of the test bearing to conduct the long-duration experiment for exploring its tribological and vibrational behaviours under starved lubricating condition using micro size MoS2 blended grease. The performance behaviours of the textured race bearing have been compared with conventional bearing (i.e. having both races without textures) under the identical operating conditions for demonstrating the advantages of textured race. Design/methodology/approach Texture was created on stationary race of the test ball bearing (51308) using nano-second pulsed Nd: YAG laser. Performance parameters (frictional torque, temperature rise and vibrations) of textured ball bearings were measured under severe starved lubricating conditions for understanding the critical role of texture in the long duration of the test. S-type load cell and miniature accelerometer were used for measuring the frictional torque and vibration, respectively. Bulk temperature at stationary races (at the back side) of test bearings was measured in operating conditions using a non-contact infrared thermometer. Findings Significant reduction in frictional torque and decrease in amplitude of vibration with textured ball bearing were found even under the severe starved lubricating condition in comparison to conventional bearing. Originality/value There is dearth of research pertaining to the performance behaviours of ball bearings using textures on the races. Therefore, an attempt has been made in this study to explore the tribo-dynamic performance behaviours of a thrust ball bearing using a texture on its stationary race under severe starved lubricating condition for the longer duration of the test.
Blast induced ground vibration is a crucial parameter in determining safe charge levels and minimising the damage to the surrounding structures. A number of empirical equations have been proposed for prediction of peak particle velocity (PPV), but no empirical formula has yet been established for the prediction of frequency. In order to minimise the blast damage and the blasting related loss, it is important to study the parameters influencing blasting. In the present case, the adaptive neuro-fuzzy interface system (ANFIS) model was used to predict the PPV and frequency using blast design, rock properties and explosive parameters from the Northern Coal Field open pit mine in MP, India. Results were also compared using multivariable regression analysis (MVRA) to further prove prediction capability. The ANFIS approach shows very good prediction capability for PPV and frequency. The coefficients of correlation between predicted and measured PPV and frequency are 0?9986 and 0?9988 respectively.
This paper presents the findings of an experimental study performed for exploring and improving the tribodynamic performance behaviours of a thrust ball bearing employing circumferential microgrooves on the stationary upper race. Investigations were conducted using oil and grease lubricants and operating the bearings at light loads (in the vicinity of requisite minimum loads characterised by p H =0.4 and 0.6 GPa) and speeds varying in the range of 1.8-4.0 m s −1 at the ambient condition. The effects of micro-grooved stationary races on frictional torque, temperature rise and vibrations of the bearings were measured and have been discussed herein. The surface topographies of races and balls of used test bearings were examined after finishing the experiments for extracting the surface topographies based technical information. Significant reductions in the magnitudes of frictional torque (14%-21%), bulk temperature rise of race (14%-26%), vibrations (7%-34%) were found with micro-grooved bearings (pair of conventional moving lower races and micro-grooved upper stationary races) in comparison to the conventional bearings (pair of conventional races). Moreover, the oil lubricated micro-grooved bearings yielded substantial improvement in the tribo-dynamics as compared to grease lubricated case irrespective of the operating parameters i.e. loads and speeds.
Ball bearings encounter grease being pushed aside from the concentrated contact of their rolling elements and races due to the continuous motion of balls. This yields lubricant starvation at the contacts inside the bearings. In this situation, the tribological and vibration performances of ball bearings deteriorate. Therefore, improving the performance behaviors of ball bearings despite starvation is a vital research task. Thus, the objective of this paper was set to explore improving the performance behaviors of a ball bearing employing nanoflake (molybdenum disulfide (MoS2), tungsten disulfide, and hexagonal boron nitride)-blended greases. This paper reports the comparisons of frictional torque, temperature rise, and vibrations of test bearings lubricated with fresh and nanoflake-blended greases. The surfaces of races were examined after the experiments using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The surface topographies of races and balls were captured using a 3-D profilometer for comparison. The blended greases yielded significant reductions of 17–33, 16–23, and 8–64 % in frictional torque, temperature rise, and vibration, respectively. Surface analyses of races also revealed better tribofilm formation in the presence of MoS2 in grease compared with the other cases.
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