基于自转一阶非连续式微球双平盘研磨的运动学分析与实验研究

Kinematic Analysis and Experimental Study of Microsphere Double-plane Lapping Based on Rotation Function First-order Discontinuity

目的分析不同研磨压力、下研磨盘转速、保持架偏心距和固着磨料粒度对微球精度的影响,确定自转一阶非连续式双平面研磨方式在加工GCr15轴承钢球时的最优研磨参数,提高微球的形状精度和表面质量。方法首先对自转一阶非连续式双平盘研磨方式微球进行运动学分析,引入滑动比衡量微球在不同摩擦因数区域的运动状态,建立自转一阶非连续式双平盘研磨方式下的微球轨迹仿真模型,利用MATLAB对研磨轨迹进行仿真,分析滑动比对研磨轨迹包络情况的影响。搭建自转一阶非连续式微球双平面研磨方式的实验平台,采用单因素实验分析主要研磨参数对微球精度的影响,得到考虑圆度和表面粗糙度的最优参数组合。结果实验结果表明,在研磨压力为0.10 N、下研磨盘转速为20 r/min、保持架偏心距为90 mm、固着磨料粒度为3000目时,微球圆度由研磨前的1.14μm下降至0.25μm,表面粗糙度由0.1291μm下降至0.0290μm。结论在自转一阶非连续式微球双平盘研磨方式下,微球自转轴方位角发生突变,使研磨轨迹全覆盖在球坯表面。随着研磨压力、下研磨盘转速、保持架偏心距的增大,微球圆度和表面粗糙度呈现先降低后升高的趋势。随着研磨压力与下研磨盘转速的增大,材料去除速率不断增大,随着保持架偏心距的增大,材料去除速率降低。随着固着磨料粒度的减小,微球的圆度和表面粗糙度降低,材料去除速率降低。

Microspheres are critical components of precision machinery such as miniature bearings and lead screws.Their surface quality,roundness,and batch consistency have a crucial impact on the quality and lifespan of mechanical parts.Due to their small size and light weight,existing ball processing methods are used to achieve high-precision machining of microspheres.Traditional concentric spherical lapping methods,with three sets of circular ring trajectories,result in poor lapping accuracy.To achieve efficient and high-precision processing of microspheres,the work aims to propose a method based on the first-order discontinuity of rotation for double-plane lapping of microspheres.Firstly,the principle of the first-order discontinuity of rotation for double-plane lapping of microspheres was analyzed,and it was found that the movement of the microsphere changed when it was in different regions of the upper variable friction plate,resulting in a sudden change in the microsphere's rotational axis azimuth and expanding the lapping trajectory.Next,the movement of the microsphere in the first-order discontinuity of rotation for double-plane lapping method was analyzed,and the sliding ratio was introduced to measure the motion state of the microsphere in different friction coefficient regions.It was observed that the sliding ratio of the microsphere varied in different friction coefficient regions.As a result,when the microsphere passed through the transition area between the large and small friction regions of the upper variable friction plate,the sliding ratio changed,causing a sudden change in the microsphere's rotational axis azimuth and expanding the lapping trajectory.The lapping trajectory under different sliding ratios was simulated by MATLAB,and the results showed that with the increase in simulation time,the first-order discontinuity of rotation for double-plane lapping method could achieve full coverage of the microsphere's lapping trajectory,making it more suitable for precision machining of microspheres.Finally,based on the above research,an experimental platform for the first-order discontinuity of rotation for double-plane lapping of microsphere was constructed.With 1 mm diameter bearing steel balls as the processing object,single-factor experiments were conducted to study the effects of lapping pressure,lower plate speed,eccentricity of the holding frame,and grit size of fixed abrasives on microsphere roundness,surface roughness,and material removal rate.The experimental results showed that under the first-order discontinuity of rotation for double-plane lapping,the microsphere's rotational axis azimuth underwent a sudden change,leading to full coverage of the lapping trajectory on the microsphere's surface.Under the lapping pressure of 0.10 N,the lower plate speed of 20 r/min,the eccentricity of the holder of 90 mm,and the grit size of fixed abrasives of 3000 meshes,the roundness of the microsphere decreased from 1.14μm before lapping to 0.25μm,and the surface roughness decreased from 0.1291μm to 0.0290μm.As the lapping pressure and lower plate speed increased,the microsphere roundness and surface roughness were firstly improved and then deteriorated,while the material removal rate continuously increased.As the eccentricity of the holding frame increased,the roundness was firstly improved and then deteriorated,while the material removal rate decreased.As the grit size of fixed abrasives decreased,the microsphere's roundness and surface roughness were improved,and the material removal rate decreased.Through the experiments,the optimal parameter combination considering roundness and surface roughness is obtained:lapping pressure of 0.10 N/ball,lower plate speed of 20 r/min,eccentricity of the holder of 90 mm,and grit size of fixed abrasives of 3000 meshes.