On The Lubricant Replenishment Induced By Bearing Intrinsic Characteristics With Singlecharge Amount

This work aims to explore the potential lubricant replenishments induced by bearing intrinsic characteristics and the corresponding influences on lubrication status under single-charge amounts.As a key component of mechanical equipment,the performance of rolling bearings closely related to lubrications will impact the service reliability of the whole machine.A simple ball-on-disc single contact configuration was employed to simulate the rolling element-race contact,which has become an effective approach for fundamental research on bearing lubrication.Furthermore,via an optical interferometry method,the detailed features of lubricating contacts were visualized.In view of the situation that the rolling bearings frequently operate under starvation conditions,the optical ball-on-disc test device was hence used to reveal the starvation mechanisms as well.The results from this type of simulation device show that poor lubrication will occur in a short period.However,a real bearing in fact runs a rather long term even under starvation conditions.Thus,there must exists some potential mechanisms that dominate the lubricant replenishment and hence improve the lubrication states.The underlying replenishment mechanism may be closely associated with the bearing intrinsic characters.Although,several replenishment factors were individually introduced to the simulation device in the previous studies,the bearing characteristics were not fully reproduced and the replenishment effects were not well reflected.There are still many typical replenishment factors to be explored.Therefore,based on the characteristics of rolling bearings such as kinematics,contact geometry and structure.Through the changes in driving mode,support type and numbers of rolling elements,some new factors that affect replenishment are introduced.The replenishment effects and the corresponding lubrication states from these factors are observed.To facilitate the occurrence of starvation,only a single charge amount of lubricant was applied.The main content includes:(1)Lubricant replenishment induced by the slip of rolling element.Using the ballon-disc single contact device,different rolling sliding ratios were obtained by controlling the rotation of ball and disc respectively,which reflects the slips of rolling elements.The effects of lubricant amount,viscosity and load on the film thickness and friction coefficient were observed,based on which the lubricant replenishments were revealed.The rolling speed of ball relative to the disc affects the lubricant replenishment.(2)Lubricant replenishment induced by the contact geometry.By designing a novel ball support with a curved raceway,the contact factor between rolling element and bearing raceway was hence introduced to the ball-on-disc single contact device.The comparisons of lubricant replenishment by different types of ball support were given.Moreover,the effects of contact curvature on replenishment and lubrication states were analyzed.(3)Lubricant replenishment induced by the motion of rolling elements.The number of rolling elements,cage,spin effect and motion orbit of elements were introduced using a multi-contact thrust rolling bearing device.The lubrication state comprehensively considering these factors were observed.By comparing with the results from singlecontact device,the contributions to the lubricant replenishment from these factors were analyzed.In addition,the differences in materials between the simulation device and rolling bearing were also considered.The wettability of lubricant on glass and steel surface may be different,which consequently affects the lubricant replenishment and lubrication states.To measure the film thickness in steel-steel contacts,a capacitance method was employed and a preliminary observation and results were given.In the present work,some bearing characteristics were introduced into the test devices and the effect of these factors on lubricant replenishment and lubrication states were observed.The results show some underlying mechanisms that contributes to the long-term service of the bearing.This study may strengthen the understanding of lubricant replenishment inside the rolling bearing,based on which it may give the inspiration to the bearing design in the aspect of replenishment enhancement.