Observation And Analysis Of Lubrication Flow In Point Contacts Based On High Speed Photography

The lubrication in point contact area has been a hotspot in tribology research for along time. Study on the lubrication has been going deep with the improvingrequirements of lubricant performance of mechanical components. As a result, variousnew techniques have been used in experimental study on lubricate condition.Dynamic lubricant flow characteristics in point contact area have been studied inthis paper.An instrument was designed for simulating the lubricant flow in point contact areaunder different conditions and observing the flow characteristics using high speedphotography.The flow properties of grease in different conditions of point contact areas wereobserved.Different entrainment velocities were obtained by adjusting the speed of steelball and glass disc. Meanwhile, different contact stresses were obtained by adjusting theload applied on the steel ball. A large amount of images was received by observing thelubrication state of pure grease and the flow properties of grease containing tracerparticles through the contact area by using high speed camera.Programs for extracting information from the observed image were developed,which can be used to extract the film shape and the velocity information of lubricate inpoint contacts, thus providing an effective methods for the treatment of experimentalresults.The influence of the entrainment velocity and contact stress on the velocity ofgrease during the contact area was studied. Some conclusions can be found from theresults. The flow state of grease through the contact area basically is laminar, and theaverage velocity of the grease is slightly lower than the entrainment velocity. With theincrease of the contact stress, the degree of the reduction is decreased. The greasegathered in the entrance of the contact area and separate to the two sides when crossingthe contact area, the degree of the gather and separate is increased with the entrainmentvelocity increasing. The degree of the velocity fluctuation of grease is relative to itsposition. The degree of the velocity fluctuation of grease near the exit is larger than thegrease near the entrance. Analysis of the lubricant film shape of the point contact regionshows that the film shape of grease lubrication is similar to the oil lubrication.