Tribological Characteristics of Porous Bearings under Micro-load Ⅱ. Experimental Study of Friction

Performance and tribological character of journal porous bearings under micro-load were studied.The test results were obtained with wavelet signal process.Results show that instantaneous friction coefficient does not keep constant even under steady exterior micro-load due to tribo-structure and manufacture error,and it varies with operation condition such as type of lubricants,rotation speed of shaft,exterior load and oil starvation state.Under micro-load state and with shaft rotation speed 600,1%~2% volume ratio of liquid crystal to 46~# machinery oil yields the lowest friction coefficient.The friction coefficient shows a parabola curve of low-high-low with the shaft rotate speed rising form 600~3 000.Instantaneous friction coefficient shows a tendency of high-low-stable with the increase of exterior load from 0.5 to 10.Compared with starved lubrication,the flood lubrication displays a higher friction coefficient.Mixed lubrication may result in unsteady state as shaft rotation speed is higher than 1 500~2 400.