Study On Machining Process For High Precision Cylindrical Surface Of Cylindrical Rollers

Bearing is basic component of manufacturing,it is important for the development of high precision machine,energy mechanical and high-speed spindles and so on.High consistency and high precision cylindrical roller have a decisive impact on the quality and lifetime of bearing.Currently centerless grinding is the main methods of machining cylindrical roller,but it has common problems of low machining precision.For that reason,this paper propose a eccentricity swing processing method for outer circle of cylindrical roller to achieve high accuracy and high surface quality.Studies have shown that the trajectory distribution on the cylindrical surface have an important role on the processing uniformity and roundness.Therefore,this paper builds mathematical model by kinematic analysis and obtain the rolling angular velocity of cylindrical roller at the eccentricity swing processing method for outer circle of cylindrical roller.The simulation results show the rotational speed ratios between the carrier’s rotation speed and lower plate’s speed.should be approximately equal to 1,while the absolute value of the offset curve is greater than the absolute value of amplitude.The simulation of processing trajectory on the cylindrical surface of workpiece and the evaluation of its uniformity is proposed for the eccentricity swing processing method for outer circle of cylindrical roller.The influence of the rotational speed ratios between the carrier’s rotation speed and lower plate’s speed on the trajectory distribution is discussed.Through the single factor experiment to optimize the rotational speed ratio,and identified three groups as the optimal combination.On this basis,effect of motion types on cylindrical surface topography are studied and the result is that When the upper and lower plates,the eccentric wheel and outer ring gear simultaneously rotate is the best motion type.Lapping process are studied at different particle size of Al₂O₃abrasive for the eccentricity swing processing method for outer circle of cylindrical roller.The workpiece is GCr15 bearing steel cylindrical roller of Ⅲ Class.And this paper takes orthogonal experiment to determine the optical speed ratio and the effects of different technological parameters in1000#abrasive of Al₂O_3.At the condition of optimized speed,this paper study the different granularity of Al₂O₃processed results with time.Polishing process are studied for the eccentricity swing processing method for outer circle of cylindrical roller.Chemical mechanical polishing（CMP）method is utilized to improve the surface qulity and shape accuracy and two steps are taken which are rough polishing and fine polishing.At different polishing stages,this paper analysis the mechanism of material removal.This paper uses the eccentricity swing processing method for outer circle of cylindrical roller,the workpiece’s material of the cylindrical roller（Ф20*30）is GCr15 and its initial accuracy coform with Ⅲ class,after lapping 30min with the process condition that the concentration of 5000#Al₂O₃ slurry is 20%;the loading pressure is 10N/rolle;the upper plate’s speed is-76r/min,the lower plate’s speed is 84r/min,eccentric wheel’s speed is 80r/min,the outer ring is 48r/min and the flow is 25ml/min,the roundness average of 0.47μm and roughness average of 45nm can be obtaine which have reached the standard of Ⅰ class in terms of roundness and roughness.In order to improve the surface quality and shape accuracy of cylindrical roller,this paper applys CMP method after lapping in the condition that the speeds combination is above-described,the loading pressure is 20N/rolle and the flow is 80ml/min The result is that the roundness average of 0.16μm and roughness average of 0.31μm can be obtaine which have reached 0 class in terms of roundness and roughness.