| High-precision microspheres are key components in miniature precision bearings,and their accuracy plays a decisive role in the quality and life of miniature bearings.In view of the fact that the existing spherical processing method is difficult to meet the requirements of high-precision microsphere processing,therefore,this paper proposes a method of finishing microsphere with dual-plane lapping based on eccentric cage,which is suitable for the high precision microsphere processing.The main work of this paper includes the following aspects:(1)Based on the geometric kinematics theory,the spherical geometric kinematics model of a method of finishing microsphere with dual-plane lapping based on eccentric cage is established,and the expression of the equation of motion is obtained.Based on Matlab,the spherical trajectory simulation model is established,and the spherical processing trajectory simulation comparison experiment is carried out with other sphere processing methods.Simulation experiments were carried out with other spherical machining trajectories.The simulation results showed that the method of dual-plane lapping based on eccentric cage can achieved uniform full envelope of spherical machining trajectories,which is beneficial to the processing of high precision microspheres.(2)Based on the basic conditions of the ball and the kinematics model of the sphere,combined with the rigid body kinematics and the principle of the rotation of the space coordinate system,the simulation method of the spherical machining trajectory is derived,and the kinematics model,a spherical processing trajectory quantization method was built.The spherical surface was divided into regions according to the same area.The grinding trajectory of each region was quantified according to the principle of equal length,and the statistical data was weighted according to the difference of the grinding effect.The standard deviation of the statistical data was used as the evaluation of the uniformity of the grinding trajectory distribution.The uniformity of the spherical processing trajectory of the processing method proposed in this paper was evaluated and compared with the original evaluation method.The results showed that the uniformity trajectory of the surface of the method of dual-plane lapping based on eccentric cage was better than the traditional processing method.(3)Simulation experiments were carried out using Matlab,the spherical processing trajectory distribution and the processing track point density difference SD are used as evaluation parameters,and the spherical processing trajectory uniformity under different parameters such as different lower grinding wheel speed,hole holding distance,eccentricity and ball diameter.The comparative analysis shows that the lower grinding disc speed,eccentricity and hole holding distance have different effects on the spherical grinding trajectory distribution and the processing trajectory point density difference SD.The spherical diameter variation on the spherical processing trajectory distribution and processing trajectory point Density difference SD value has little effect.(4)The experimental platform for the method of dual-plane lapping based on eccentric cage was built.The single factor process experiment was carried out,and the simulation was verified.The effects of process factors such as lower grinding disc speed,eccentricity and machining load on the surface roughness and sphericity error of the sphere were studied.The single factor process experiment was carried out to study the effects of process factors such as lower grinding wheel speed,eccentricity and processing load pressure on the surface roughness and sphericity.The orthogonal experiment was designed and the optimal processing parameters were: processing load 1N/ball,lower grinding disc speed 15 rmp,and slurry concentration 10%.Taking the bearing steel ball as the experimental object,the processing experiment was carried out with the optimal process parameters,and the obtained sphere reached the accuracy of G5 level. |
