基于圆弧轨迹进给的球轴承套圈沟道ELID成形磨削机理

The geometric precision and surface quality of bearing ring groove influence the rotary precision and fatigue life of bearings. Traditional superfinishing processing is insensitive to geometric precision, and it is difficult to improve the shape and position errors caused by former processing. Meanwhile, the traditional grinding process is also difficult to reach high shape accuracy and small surface roughness values. Considering the features of traditional bearing ring superfinishing and electrolytic in-process dressing (ELID) grinding, this project will propose a new processing technology based on the circular trace feed and ELID coupled technology, that is, an ELID profile grinding of bearing ring groove based on circular trace feed. In this project, the shape accuracy of the ring groove can be achieved by reciprocating feed of circular trace which rotates around the center of ring groove arc or, around the center of grinding wheel arc; meanwhile, the ELID grinding technology can realize the ultra-precision machining of ring groove surface. This project will focus on the machining the outer ring of the of ball bearing groove. The geometric precision formation mechanism for the new grinding process will be investigated, in addition, the formation mechanism of oxide film at wheel surface and the machined surface of bearing ring groove at the processing conditions of circular trace feed and the workpiece negative electrode will also be studied, to improve the machining accuracy and surface quality for outer ring of the of ball bearing groove. This research has great theoretical meaning and practical value to the development of high precision ball bearing. It can provide a technical support for the development of high level equipment manufacturing technology.

套圈沟道几何精度和表面质量直接影响球轴承的回转精度和疲劳寿命。项目针对传统沟道超精研加工工艺对形位精度不敏感，修正前工序沟道廓形误差和位置误差能力较弱的特点以及传统沟道磨削工艺在廓形精度和表面粗糙度方面的不足，综合传统沟道超精研加工和ELID超精密磨削的技术特征，提出一种圆弧轨迹进给与ELID技术相结合的沟道成形磨削新工艺——基于圆弧轨迹进给的球轴承套圈沟道ELID成形磨削。一方面利用套圈绕沟道圆弧中心或砂轮绕砂轮圆弧中心往复摆动实现圆弧轨迹进给以保证套圈沟道的廓形精度；另一方面利用ELID磨削技术实现对沟道表面的超精密加工。项目拟以球轴承外圈沟道为对象，研究新磨削工艺的几何精度创成原理，探究圆弧轨迹进给和工件阴极条件下砂轮表面氧化膜形成和沟道表面创成机理，提高球轴承外圈沟道加工精度与表面质量。对高精度球轴承的发展具有重要的理论意义和实用价值，可为我国高端装备制造技术的发展提供重要保障。

套圈沟道几何精度和表面质量直接影响球轴承的回转精度和疲劳寿命。项目针对传统沟道超精研加工工艺对形位精度不敏感，修正前工序沟道廓形误差和位置误差能力较弱的特点以及传统沟道磨削工艺在廓形精度和表面粗糙度方面的不足，综合传统沟道超精研加工和ELID超精密磨削的技术特征，提出一种圆弧轨迹进给与ELID技术相结合的沟道成形磨削新工艺—基于圆弧轨迹进给的球轴承套圈沟道ELID成形磨削。一方面利用套圈绕沟道圆弧中心或砂轮绕砂轮圆弧中心往复摆动实现圆弧轨迹进给以保证套圈沟道的廓形精度；另一方面利用ELID磨削技术实现对沟道表面的超精密加工。项目搭建了基于圆弧轨迹进给的直线沟道ELID成形磨削试验平台，并在该平台上进行了砂轮表面氧化膜形成机理与沟道表面创成机理的研究。在氧化膜的形成方面，摆动角度主要通过影响砂轮表面氧化膜的覆盖面积，从而影响最终氧化膜的形成，随着摆动角度的增大，电解电流逐渐增大，砂轮表面氧化膜厚度逐渐减小；摆动速度主要通过影响砂轮表面氧化膜的去除，从而影响最终氧化膜的形成，随着摆动速度的增大，电解电流逐渐增大，砂轮表面氧化膜厚度逐渐减小。在沟道表面创成方面，沟道表面粗糙度随着摆动角度和摆动速度的增大而增大，表面轮廓度随着摆动角度的增大而增大，而随着摆动速度的增大而减小。对比有无圆弧轨迹进给的直线沟道ELID成形磨削，基于圆弧轨迹进给的直线沟道ELID成形磨削的沟道表面粗糙度可达Sa56.593nm、沟道表面轮廓度为可达Pt0.5911μm，均明显优于切入式成形磨削，验证基于圆弧轨迹进给的ELID成形磨削在提高沟道几何精度和表面质量方面的能力。项目还对在沟道磨床上可以实现基于圆弧轨迹进给条件的多种五轴配置方案进行了几何精度分析和数值仿真分析，得出基于圆弧轨迹进给的五轴配置策略，并搭建了基于圆弧轨迹进给的球轴承套圈沟道ELID成形磨削试验平台。新工艺的实施对提高球轴承套圈沟道的形位精度进而提升球轴承的品质具有重要的理论意义和实用价值。