定偏心锡磨盘超精密平面抛光均匀去除模拟计算(Ⅰ)

定偏心平面抛光中，工件表面各区域材料的均匀去除问题涉及工件加工后的面形。本文从理论上讨论了锡磨盘与工件的转速比、偏心距及转速对工件表面面形的影响，以及工件边缘露出磨盘的情况下，表面的不均匀去除程度。模拟计算结果表明当转速比为１，工件不露出磨盘时，可以实现工件材料的均匀去除。     

不定偏心平面研磨均匀性的研究

提出了一种新的不定偏心平面研磨方式,主动驱动工件使其在绕自身回转轴自转的同时,绕垂直于研磨盘表面的轴线公转.该方式涵盖了定偏心研磨和行星轮式双面研磨.对该方式进行了运动分析,得到了工件相对于研磨盘速度的表达式.在Preston方程基础上,建立了材料去除函数和研磨均匀性函数.理论分析和仿真结果表明,通过设置选择适当的转速比组合,可使工件获得均匀研磨.讨论了转速比与偏心距对研磨均匀性的影响.     

无理偏摆式平面研磨加工均匀性的数值模拟

基于定偏心平面研磨方式,提出了无理转速比下的偏摆式平面研磨方式.采用矢量方法建立了偏摆式平面研磨加工的运动学方程,对比分析了定偏心和偏摆式驱动下的工件表面磨粒轨迹和磨粒速度场的分布形态,并建立了运动轨迹密度均匀性和材料去除量均匀性的区域划分和统计评价方法.研究表明:偏摆式驱动下的平面研磨轨迹线更加复杂无序,磨粒覆盖面积更大,能更快地获得更均匀的轨迹线分布,且在无理转速比下无明显牛顿环现象,轨迹线的均匀性显著提高;相同转速比时两种驱动方式下磨粒速度场分布形态类型相同,但偏摆式下单颗磨粒的速度大小和速度方向角随时间变化均无明显周期,能获得的速度大于定偏心方式,更快地实现材料去除且无理转速比下的材料去除性更为均匀.最后搭建两种驱动方式的试验平台进行研磨对比试验,通过无理偏摆式加工方式后硅片获得的表面粗糙度Ra最低,且相同时间内的材料去除量最大.     

锡磨盘定偏心平面研抛中材料去除模拟

本文使用超精密平面研磨机及锡磨盘进行超光滑表面的抛光研究,平面抛光中,锡磨盘表面的形貌和加工状况直接影响被加工工件的表面平面度。本文基于Ｐｒｅｓｔｏｎ方程,建立了在定偏心抛光条件下,被加工材料的去除模型,。针对锡盘开有同心圆等沟槽的表面加工状况,提出了一种计算材料有效去除的算法,计算了工件的表面去除误差,对抛光后工件表面形貌提出理论预测。     

无理数转速比下的平面研磨轨迹均匀性研究

平面研磨过程中磨粒与工件的相对运动轨迹分布对工件表面质量有重要影响。针对有理数转速比下的研磨加工过程中磨粒轨迹重复的问题,对磨粒相对工件的运动轨迹进行了研究,分析了典型的定偏心式主驱动方式平面研磨过程中磨粒轨迹对抛光均匀性的影响,提出了一种无理数转速比的平面研磨加工方法,利用Matlab工具对无理数转速比平面研磨加工进行了运动学仿真,理论分析了基于螺旋线磨粒排布的研磨盘在无理数转速比下的磨粒轨迹均匀性。仿真结果表明,无理数转速比下的磨粒轨迹线是开放的,其在均匀性方面优于有理数;对于不同无理数转速比,研磨轨迹均匀性随着转速比的增大而提高,但随着研磨时间的增加其均匀性趋于相同。该研究为无理数转速比平面研磨抛光设备的研制提供理论依据。     

玻璃烫钻多头研磨机研磨轨迹仿真

采用虚拟样机技术,对偏心式玻璃烫钻多头研磨机进行了研磨轨迹仿真。仿真了研磨盘自转转速和工件载盘在不同转速比的情况下,研磨盘上一点相对于载盘的轨迹,取得了在不同转速下的研磨轨迹图形。对仿真得出的研磨轨迹进行分析,并结合研磨技术的要求,得到了理想的研磨轨迹。     

基于最大熵原理的平面研抛工艺参数优化

提高光学零件研抛加工精度的关键是优选工艺参数。对此提出一种基于最大熵原理的平面研抛工艺参数优化方法。建立了工件研抛信息熵的数学表达式并给出了相关的物理解释,并对定偏心平面研抛工艺参数优选进行了数值模拟计算。研究结果表明,在定偏心平面研抛中,选择工件与研抛盘同方向等速转动可以使工件表面材料去除均匀,选择较大的偏心率可以提高加工效率,同时应实时修整研抛盘以减小研抛盘磨损对工件加工精度的影响。     

研磨驱动方式和转速比对磨粒运动轨迹的影响研究

针对常规平面研磨过程中磨粒运动轨迹重复性较高、研磨抛光均匀性不足的问题,引入了无理转速比概念,以进一步提升研磨加工均匀性。建立了定偏心主驱动式和直线摆动驱动式下的轨迹数学模型,通过Matlab进行了运动学仿真,对两种驱动方式和不同转速比下的单颗与多颗磨粒运动轨迹进行了对比研究,最后用离散系数对两种驱动方式在不同转速比下的研磨轨迹均匀性进行了分析。研究结果表明:当转速比为有理数时,研磨轨迹重复,转速比大小与驱动方式对轨迹均匀性影响较大;而当转速比为无理数时,研磨轨迹开放不闭合,其轨迹均匀性优于有理数的,且转速比大小与驱动方式对轨迹均匀性影响较小;该研究为选择合理的驱动方式与转速比提供了理论依据,有利于工件被加工表面质量的提高。     

行星式抛光装置设计

设计了一款可应用于机器人抛光作业且具有行星运动功能的抛光装置。设计了控制系统,并对其去除函数进行了研究,分析了偏心距、公自转速比等参数对其去除函数的影响。通过仿真计算得出,当取转速比f=4、偏心率e=0.8时可获得较为理想的去除函数,理论上可获得更高质量的抛光表面。     

偏心距在偏心抛光中对去除速率均匀性的影响

从相对运动的角度出发,首先分析了在固结磨料抛光中工具与工件的相对运动轨迹.而后从纯机械去除的角度出发,利用有限元的思想,建立了工件去除速率的数学模型,并分析了偏心距对工件去除速率均匀性的影响规律.结果表明:在偏心距一定时,如果工件外圈有一部分和抛光垫内圈或者外圈相交,那么工件的去除速率沿半径方向的变化为:先增大后急剧减小;如果全部工件完全与抛光垫接触,那么工件的去除速率沿半径方向的变化趋势为不断增大,而且先增大较快,后趋于平缓.在偏心距变化时,当工件完全位于抛光垫上时,随着偏心距的增大,工件上各个半径处的去除速率有明显增大的趋势.     

亚纳米量级光滑表面的超精密抛光

软Ｘ射线光学的发展，对光学元件表面提出超光滑要求，为此我们开展了使用锡磨盘的超精密抛光方法研究。本文介绍锡磨盘磨削的实验装置及主要结果。利用这种方法已加工出表面粗糙度优于０．３ｎｍ的超光滑表面     

金相研磨抛光机自动控制系统的研究

金相检验是确定材料组织最可靠的方法。金相试样的质量最终是由抛光质量决定。根据制备金相试样的技术要求 ,在现有抛光机的基础上对其自动控制系统进行了技术改造 ,使其具有更高的精度。对显示面板重新设计提高可操作性和界面美观度。为金相试样制备提供一种更友好的操作界面。     

计算机硬磁盘CMP中抛光工艺参数对去除率的影响

对于计算机硬磁盘的生产,为了最大限度地提高盘片生产量,降低生产成本,要求化学机械抛光(chemieal mechanical polishing,简称CMP)中在保证优质表面质量情况下,实现最大去除量(Material Removal,简称MR)和去除率(Material Removal Rate,简称MRR)。本文讨论了硬盘片的化学机械抛光过程中的外加压力、转速和抛光时间对去除率的影响。实验采用含多种添加剂的纳米二氧化硅(SiO_2)胶体作为研磨液在双面抛光机上对镍磷敷镀铝镁合金基片进行精抛光。结果表明,不降低表面质量,MRR随着压力的增加而增大到一个最大值,随后随着压力继续增加而减小;增加抛光机下盘的转速将使MRR变大到一定值后再下降;增加抛光时间将使MR增大,而MRR变化是非线性的。     

超细氧化铝表面改性及其抛光特性

在化学机械抛光（CMP）中，为了提高氧化铝磨料分散稳定性和防止团聚，利用丙烯酰氯对超细氧化铝进行了表面改性，并用XPS、激光粒度仪、SEM对其进行表征，结果表明改性后的超细氧化铝分散性明显提高。研究了改性后超细氧化铝在数字光盘玻璃基片中的化学机械抛光特性，即外加压力、抛光时间和下盘转速对玻璃基片去除量的影响,并对其CMP机制进行了推断。结果表明，材料去除量随下盘转速、压力变化趋势相近，即随着压力的增加或下盘转速的提高，材料去除量先增大后减小；随抛光时间延长，抛光初期材料去除量增加较快，但在后段时间内去除量增加趋势趋于平缓。     

Effect of slurry injection position on material removal in chemical mechanical planarization

In this paper, the effect of slurry injection position on removal rate and nonuniformity was experimentally investigated on a 300-mm polisher developed by the authors, and the effect of slurry injection position on slurry fluid pressure distribution during polishing was also measured by a novel in situ fluid pressure measurement system integrated in the polisher. In situ pad conditioning was employed in all experiments. The results showed that removal rate, nonuniformity, and fluid pressure distribution were influenced dramatically by the slurry injection position. The slurry injection position determines the slurry distribution, and therefore, the removal rate profile and fluid pressure distribution were affected.     

The concept of high angle wedge polishing and thickness monitoring in TEM sample preparation.

The concept of high angle wedge polishing for TEM non-metal sample preparation is introduced for the first time. Also, introduced is the concept of converting lateral distance measurement into vertical thickness measurement in monitoring TEM sample thickness. Based on the Tripod polisher, Quadripod was constructed using these two concepts. Fast and reliable TEM sample preparation (mechanical polishing down to electron transparency) can be achieved using the Quadripod. In addition, Quadripod offers the ability of locating a specific area of interest.     

Predicting the Material Removal in Polishing: The Applicability of Two Types of Statistical Models

This article develops two statistical rough surface models to investigate the material removal rate in surface polishing. Model I implies that the contact between two surfaces is equivalent to that between a composite surface and a plane; but Model II is without the equivalent surface concept. The prediction differences of the two models were first investigated with the aid of contact mechanics. The analysis shows that the relative error of the predictions by the two models could be minimized by considering the interactions between asperities, and that this error increases with the separation of the mean planes, but decreases with the asperity density, asperity radius and standard deviation of the asperity height. By extending the models to study the material removal rate in polishing, it was found that asperity interaction is an important factor in a statistical modelling of polishing, and that with a given separation of the reference planes of the pad and workpiece surfaces, the material removal rate increases with the volume concentration of abrasive particles and varies with the pad roughness. The study also showed that the microstructure of a polishing pad has a significant effect on the material removal rate of a polishing.     

Morphology of Co–Cr–Mo dental alloy surfaces polished by three different mechanical procedures

The present study aims at characterizing the three‐dimensional (3‐D) morphology of a Co–Cr–Mo dental alloy surface as a result of three different procedures used for polishing it. The sample surface morphology of the sampled surface was examined employing atomic force microscopy (AFM), statistical surface roughness parameters, and fractal analysis. An extra‐hard dental alloy of cobalt–chromium–molybdenum (Co–Cr–Mo) (Wironit^®, from BEGO, Bremen, Germany) was prepared and moulded. Different polishing treatments were carried out on three groups of six samples each—a total of 18 samples. The first group contained six electropolished (EP) samples. The second group containing six samples went through a mechanical polishing process employing green rubber discs and a high shine polishing paste applied by a rotating black brush (BB). The third group comprising six samples as well went through a mechanical polishing process by means of green rubber discs, high shine polishing paste, and a rotating deer leather brush (DL). Fractal analysis on the basis of a computational algorithm applied to the AFM data was employed for the 3‐D quantitative characterization of the morphology of the sampled surfaces. The fractal dimension D (average ± standard deviation) of 3‐D surfaces for BB samples (2.19 ± 0.07) is lower than that of the DL samples (2.24 ± 0.08), which is still lower than that of the EP samples (2.27 ± 0.09). The results indicated the BB samples as presenting the lowest values of statistical surface roughness parameters, thus the best surface finish, while the EP samples yielded the highest values. Microsc. Res. Tech. 78:831–839, 2015. © 2015 Wiley Periodicals, Inc.     

超声波磁流变复合抛光中几种工艺参数对材料去除率的影响

提出了一种光学抛光的新方法——超声波磁流变复合抛光。介绍了该抛光方法的基本原理和实验装置,进行了超声波磁流变复合抛光实验,采用轮廓仪实测了光学玻璃超声波磁流变抛光材料去除轮廓曲线。通过该项工艺实验,研究了五种工艺参数(磁场强度、超声振幅、抛光工具头与工件的间隙、抛光工具头转速、工件转速)对光学玻璃材料去除率的影响。在一定实验条件下,获得的材料去除率为0.139 μm/min,并获得了超声波磁流变复合抛光工艺参数与材料去除率的关系曲线,得出了光学玻璃超声波磁流变复合抛光的材料去除规律。