Study On Processing Method For High Precision Bearing Rollers With High Consistency Based On Uniform Distribution Of Cylindrical Processing Trajectory

The rolling bearing is applied widely in the machine.The cylindrical roller is the key component of bearing as one of rolling elements,its geometric accuracy,surface quality and their consistency can make great impacts on the kinematic accuracy and working life of rolling bearing.The present processing methods for the outer circle of bearing roller including centerless grinding have some technical problems,e.g.the consistency of processing accuracy is poor.To overcome these problems,a novel processing method for the outer circle of bearing roller will be proposed in the dissertation,which is developed by applying the both-sides lapping and polishing technology in the processing of roller,in order to obtain the high precision of geometric profile,surface quality and their consistency.Processing uniformity is the crucial issue to ensure the high precision of geometric profile of rolling bearing for the lapping and polishing process.Therefore,the dissertation comprises the theoretical and experimental works to specially study the key issues of both-sides cylindrical lapping and polishing process,including motion status of workpiece,processing uniformity of cylindrical workpiece,wear uniformity of flat plate,their impact factors,and so on.The main research works are summarized as below:Based on the geometry and kinematics theory,the both-sides cylindrical processing system of roller and its theoretical model are established,and the mathematical relationship between the geometric and kinematic parameters can be described.The theoretical model can be proved valid fundamentally through an experimental analysis in which the roller's motion status during processing was observed by the video and the data was processed.The rolling speed is considered as the key parameter to describe and understand the roller's rolling action.According to the analysis of simulation results,it is indicated that the rolling speed varies with time along an unstandard cosine curve;the carrier's circulation speed and its rotation speed,workpiece's position and direction are the important factors that influence the roller's rolling speed,among which the workpiece's position makes the biggest impact,the second for the ratio of speeds,and the smallest for the workpiece's direction.The carrier's circulation speed should be set in the low level,to the opposite the carrier's rotation speed.The rollermakes the steadier rolling action in the eccentric motion type than the planetary motion type.The simulation of processing trajectory on the cylindrical surface of workpiece and the evaluation of its uniformity is proposed for the both-sides cylindrical lapping and polishing process.The main steps are represented as below,after the modeling of workpiece's geometry and kinematics,the coordinates of processing trajectory points are computed,and then the processing trajectory can be simulated;the cylindrical surface of workpiece is separated to many grid unit,the processing trajectory distribution density is computed for every grid unit,then the standard deviation is computed for all the density values to quantatively evaluate the uniformity of processing trajectory distribtutied on the cylindrical surface of workpiece.According to the research results,it is indicated that the workpiece's position has the greatest impact on the uniformity of processing trajectory distribution,the second for the ratio of different speeds,and the smallest for the workpiece's direction.The uniformity of processing trajectory which is shaped as the spider web in the eccentric motion type is better than one which is shaped as the fish scales in the planetary motion type.The wear trajectory on the flat plate for the both-sides cylindrical lapping and polishing process,and the standard deviation of wear trajectory distribution density is used to quantatively evaluate the wear uniformity of plate.According to the research results,the ratio of speeds and the workpiece's position are two factors that impact the wear uniforimtiy in the almost equal level.The standard deviations of wear uniformity in the eccentric and planetary motion types are similar,but the wear trajectories of two types are very different,the interlaced epicycloid for the planetary type and the stretched epicycloid for the eccentric type.The high value of carrier's rotation speed is beneficial to improve the wear uniformity of flate plate.A both-sides cylindrical lapping and polishing machine was self-made.In the lapping experiment of GCr15 bearing roller respectively in the eccentric and planetary motion types,according to the comparison and analysis of experimental results,it is indicated that the smaller values of roundness and roughness Ra can be obtained by using the abrasive paticles of smaller size;the geometric accuracy and surface quality in the eccentric type is better than in the planetary type.Under optimal conditions of eccentric motion type,after the lapping process with mechanical removal and the polishing process with chemical-mechanical removal,the roundness average of 0.36?m with the deviation of 0.13?m was achieved for a batch of workpieces,and the roundness minimum of 0.295?m as well as the roughness minimum of 8nm were achieved for an single workpiece.The cylindrical geometric accuracy,cylindrical surface quality and the accuracy's consistency were greatly improved.