【作者】 吕冰海；

【导师】 姚英学； 袁巨龙；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2007， 博士

【摘要】 20多年来,陶瓷球在混合轴承(陶瓷球滚珠、钢制滚圈)的应用中获得了很大成功。氮化硅等先进陶瓷具有密度小、硬度高、弹性模量高(刚度高)、耐磨损、热膨胀系数低、热稳定性和化学稳定性好、绝缘、无磁等极为优良的综合性能,被认为是目前制造喷气引擎和精密机床高速主轴等仪器设备中高速、高精度轴承滚动体的最佳材料。由于传统研磨加工方法的生产工艺受到人为因素的影响,一致性和稳定性较差,加工成本高,难以获得高球度的陶瓷球,使陶瓷球的应用仍受到限制。为解决陶瓷球研磨加工过程中球面研磨不均匀、加工效率低、加工一致性差等问题,本文提出一种双转盘研磨方法,通过控制两块下研磨盘的转速组合,实现球坯表面研磨轨迹的均匀分布,使球坯表面获得均匀研磨,快速修正球形偏差,从而提高加工精度与加工效率。本文主要从研磨过程中球坯运动状态、球面研磨轨迹分布、研磨成球机理、陶瓷球面磨损及高效材料去除技术、研磨工艺分析及优化等几个方面对高精度陶瓷球的双转盘高效研磨方法进行研究。针对研磨成球第一条件——切削等概率性,采用CCD观测记录球面标识点运动轨迹和球面研磨轨迹三维分布的计算机仿真相结合的方法研究的陶瓷球研磨过程中球面研磨轨迹的分布;建立研磨轨迹均匀性的评价方法,定量评价研磨轨迹的均匀程度,探讨双转盘研磨方式对研磨轨迹均匀性的满足程度和满足条件。针对研磨成球第二条件——尺寸选择性,通过建立力学、运动学等模型分析研磨过程中球形误差修正、球坯直径的一致化以及球坯的滑动和碰撞等现象的形成机理,探讨加载方式、加工载荷的大小、球坯—研磨盘接触状态等因素对研磨成球过程的影响。为掌握陶瓷球材料的去除机理,从磨粒磨损角度探讨研磨加工中不同加工条件下陶瓷球材料的去除形式,确定材料去除形式的转换点。通过材料去除形式与材料去除率的关系的分析,提出采用光固化树脂固结的微细金刚石固着磨料盘对陶瓷球进行研磨,以提高陶瓷球粗研阶段的材料去除率。采用田口方法对陶瓷球的半精加工研磨工艺参数(加工载荷、磨料浓度和加工速度)进行优化,并讨论加工参数对加工结果的影响程度和影响规律,获得最佳的工艺参数组合。采用以上研究结果,以?5mm陶瓷球为加工对象,在粗加工阶段采用固着磨料加工技术,实现陶瓷球毛坯加工余量的高效去除,保证粗加工阶段的加工效率;在半精加工以新型双转盘研磨方式保证球度及加工一致性;最终采用化学机械抛光加工技术,保证陶瓷球坯表面质量。加工后的陶瓷球成品球形偏差为0.05μm,表面粗糙度Ra 5nm,批直径误差0.10μm,达到G3级精度要求。同时总加工时间缩短为原来的1/2~1/3。初步实现了高精度陶瓷球的高效、高一致性的加工。更多还原

【Abstract】 Over the past decade, ceramic balls have become important components in advanced bearings, and are successfully used in hybrid bearings (ceramic balls and steel races). Silicon nitride, especially, is considered as the most promising material for high speed, high temperature and high precision bearing for jet engine, high precision machine tool and apparatus because of its desirable properties.To overcome limitations in traditional lapping process, such as low precision and efficiency, low uniformity and stability of process, a new type of high efficiency lapping method for high precision ceramic ball, Rotated Dual-Plates (RDP) lapping, is developed in this paper. Under RDP lapping mode, two down plates are driven to rotate respectively in designed speed combination to achieve better uniformity of lapping trace distribution on ceramic ball surface, which will improve lapping accuracy and sphericity error correcting rate. RDP lapping method involving ball kinestate, lapping trace distribution, sphere-shaping mechanism, ball surface wear, high efficiency material removal technology, and optimization of lapping parameters are studied in this paper.In this paper, lapping trace distribution on ball surface is studied with observing the marked point on the ball surface, and 3D simulation of lapping trace. A uniformity valuation method for lapping trace is also put forward, and the uniformity requirements and satisfying degree under RDP lapping mode are discussed.To study the‘size selection’of ceramic balls in lapping process, mechanisms of sphere error correction, unifying process of ball size, ball sliding against plates and impaction between balls are studied. The influence of loading system, lapping parameters and lapping tools on sphere-shaping process is also discussed with experiments and theory analysis.The wear mode of ceramic balls involved in the lapping process is also investigated in this paper. Abrasion tests are performed with different grit size, loads and slurry concentrations on a ball-plate wear test apparatus. To improve the material removal rate of ceramic balls, a fixed abrasive lapping technology employing fine diamond abrasive and photosensitive resin is used to replace traditional free slurry lapping in rough stage.To figure out a better process for ceramic ball under RDP lapping mode, Taguchi method is applied to optimize lapping parameters to obtain the better MRR, sphericity and surface finish. Influence of parameters involving, including load, speed, and slurry concentration is discussed and the optimum lapping conditions are figured out.In the final part of this paper, a high efficiency lapping process developed in this paper for high precision ceramic ball is introduced. In this process, fixed abrasive lapping technology is adopted to improve MRR of ceramic ball in rough lapping, RDP lapping technology is employed to improve ball precision and consistency in semi-finishing stage, and CMP (chemical mechanical polishing) technology is used to obtain high surface quality in finishing. Fine sphericity (0.05μm), surface finish (Ra 5nm) and batch diameter variance (0.10μm) are obtained, and the total lapping time is reduced to 1/2~1/3 of traditional lapping process.更多还原