【作者】 王凯；

【导师】 朱永伟；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2016， 硕士

【摘要】 蓝宝石以其稳定的理化性能以及优异的光学性质,应用领域不断拓展。作为典型的硬脆材料,单晶蓝宝石高硬度和高脆性的特性使得其在加工过程中极易发生开裂,工件表面也极易形成裂纹和凹坑,这严重制约了蓝宝石的大规模应用。固结磨料技术将磨粒固结到研磨垫基体之中,使得磨粒轨迹可控,通过调整加工工艺参数,既保证了良好的材料去除效率,又能得到比较理想的加工表面质量。本文以固结磨料研磨加工单晶蓝宝石的材料去除率为研究对象,通过分析固结磨料研磨机理,建立了固结磨料研磨蓝宝石的材料去除率模型,并通过实验进行了验证。主要内容和研究成果如下:(1)基于固结磨料研磨过程的特点,将材料去除看作微小磨粒微观切削作用,通过对磨粒分布及磨粒出露的合理假设,建立实际参与材料去除的有效磨粒数;仅考虑出露磨粒与工件的接触,利用研磨过程中的力平衡关系,分别建立不考虑工件弹性回复的刚塑性假设磨粒平均切深模型和考虑工件弹性回复的弹塑性平均切深模型;结合有效磨粒数和磨粒平均切深,建立固结磨料研磨蓝宝石的材料去除率模型。(2)以建立的材料去除率模型为基础,利用MATLAB数值模拟功能绘制材料去除率随磨粒粒径、磨粒体积分数、研磨压力以及研磨速度的关系曲线,分析材料去除率与上述参数之间的关系。结果表明:刚塑性模型下磨粒粒径对材料去除率的影响不显著,材料去除率随着磨粒体积分数的增大而减小,随着研磨压力和研磨速度的增大而增大,弹塑性模型下的材料去除率整体明显低于刚塑性模型下的材料去除率。(3)开展了蓝宝石固结磨料研磨实验,并将其与相同参数下两种假设模型计算值进行比较。结果表明:实验得到的材料去除率的变化趋势与理论趋势一致,刚塑性假设下的模型计算值与实验值误差较大,弹塑性假设下的模型计算值与实验值误差较小。更多还原

【Abstract】 Because of the stable physical and chemical properties and excellent optical properties, the application areas of sapphire continue to be expanded. As a typical kind of hard brittle material,the high hardness and brittleness of the single crystal sapphire make it very easy to break, and the surface of the workpiece is easy to form cracks and pits which seriously restrict the large-scale application of sapphire. The fixed abrasive technology can consolidation the abrasive particle to the abrasive pad matrix which can make the particle trajectory under control, and than by adjusting the processing parameters, it can not only ensure the good material removal efficiency,but also get more ideal processing surface quality. This paper was focused on the material removal rate based on the lapping of sapphire with fixed abrasive, and than a material removal rate model of the fixed abrasive lapping sapphire was established and verified by experiment. The specific research contents and results are as follows:(1) Based on the characteristic of lapping process, the material removal is considered as the micro cutting of micro abrasive particles. The model of effective abrasive particle number is established by make appropriate assumptions of the distribution and emersion of abrasive particles.In consideration of the contact between the abrasive particles and the workpiece, the average cut depth model under the assumption of rigid-plastic which neglects the elastic recovery of the workpiece and the average cut depth model under the assumption of elastic-plastic which considers the elastic recovery of the workpiece are established. The model of material removal rate of the sapphire is established by combining the model of effective abrasive particle number and average cutting depth.(2) The relationship curves between material removal rate and particle size, particle volume fraction, lapping pressure and lapping speed are drawn with the numerical simulation of MATLAB based on the model of material removal rate. The results show that the influence of particle size on the material removal rate is not significant under the rigid-plastic model, the material removal rate decreases with the increase of the volume fraction of the abrasive particles, increases with the increase of the lapping pressure and the increase of the lapping speed. And the material removal rate under the elastic-plastic model is obviously less than that of the material removal rate under the rigid-plastic model.(3) The lapping experiments of the sapphire are carried out, and the results are compared with the model calculation value under the same parameters. The results show that the material removalrate trends are consistent with theoretical trends. The relative error between the calculated value and experimental value is relatively large under the assumption of rigid-plastic, while it is quite small under the assumption of elastic-plastic.更多还原