具有公自转运动形式的可更新磁流变抛光工具

在光学自由曲面的成形抛光加工当中,加工去除的稳定性对工件加工质量具有重要的影响,而抛光液的更新是保证去除稳定的关键。该文提出了一种具有公自转运动形式的可更新磁流变抛光工具,能够完成磁流变抛光液内部磁链的重组更新,使得加工去除稳定。针对此抛光工具,使用刚体润滑理论获得理论去除轮廓,通过实验获得其在单自转状态下的去除轮廓,与理论分析吻合。峰值去除量时间的实验表明,该抛光头的去除效果受时间的影响很小,抛光去除稳定。     

典型光学加工中边缘效应仿真分析

为分析光学加工中边缘效应对元件最终面形精度的影响,建立了数控小磨头行星式抛光去除函数模型和射流式工具加工的去除函数模型.通过对抛光过程中磨料载体的微观状态的研究,探讨并仿真了两种抛光方式在不同区域抛光速度分布、抛光压力分布和抛光中Preston系数的变化.通过对比分析这些参数的变化对材料去除影响,表明光学加工过程中磨料载体中分子间的作用力对边缘效应产生的影响不可忽略.     

TC4钛合金磁流变抛光的磁感应强度分布及参数

使用磁流变抛光技术对钛合金进行抛光,为了获得更好的表面质量,分别对磁感应强度分布、磁流变液和抛光参数进行了研究。首先,优化了加工区域的磁感应强度分布,通过在加工区域添加两块铁板,磁感应强度分布变得均匀,从而提高抛光后钛合金工件的表面质量。其次,分析了磁流变液的组成,即基液、磨粒类型以及磁性粒子和磨粒的质量占比对工件表面粗糙度的影响。随后,研究了四个基本抛光参数,即磨粒目数、工件转速、磁感应强度和抛光时间,找出这些参数对表面质量的影响规律。采用响应面法获得了工件表面粗糙度变化率的模型,并进行了方差分析以检查模型的显著性。最后,找出最优的抛光参数并对其进行了实验验证。     

磁流变抛光效果影响因素控制的研究

在介绍磁流变抛光原理的基础上,依据Preston方程分析了影响磁流变抛光效果的因素,根据实际加工的需要,对Preston方程进行修正,采用BK9光学工件进行抛光试验,试验结果表明,采用修正的抛光材料去除模型以及对影响抛光效果主要因素的控制,可以有效的提高抛光质量及其加工效率。     

论气囊柔性抛光技术在电梯轿厢中的应用

现如今,电梯已经越来愈普遍,对电梯轿厢的装饰也提出了更高的要求,本文介绍了一种新型的加工技术――气囊柔性抛光。它利用气囊所特有的柔性,在加工过程中始终保持与工件表面的紧密吻合,保证去除的同时也减少了工件的亚表面损伤。气囊具有可独立的控制变量：内部的压力、抛光接触区、进动运动、旋转速度。此技术十分适合运用在电梯轿壁以及轿门门板的加工上。     

磁流变抛光头形状对加工表面粗糙度的影响

设计了4种不同形状的抛光头,并使用自制的磁流变抛光液体在三轴数控铣床上对K9平面玻璃进行了磁流变抛光工艺试验.分析了在不同的磁场强度、磁极转速,加工间隙等多种情况下抛光头形状对加工表面粗糙度的影响.试验结果表明:槽型平面抛光头的抛光效果最好;同等条件下,在抛光头上开槽能有效地提高加工效率和加工质量.     

公自转磁流变抛光循环装置及其稳定性

磁流变抛光中磁流变液的循环更新是产生确定性去除的重要条件。该文针对循环系统展开分析,讨论了机械结构稳定性、磁流变悬浮液性质、循环系统压力流量稳定性及温度稳定性等因素的影响;并针对公自转磁流变抛光设备提出了特有的轮上磁流变液循环装置,开展了相关的分析和实验研究。结果表明:该轮上循环装置满足了公自转加工的要求,并且明显增强了公自转磁流变抛光设备的去除稳定性和去除效率。     

氮化硅陶瓷滚子磁流变与超声波复合抛光技术

根据氮化硅陶瓷材料的特点,研究了磁流变与超声振动对陶瓷滚子的抛光工艺。研制了适用于该工艺的磁流变液;在不同的试验参数下进行了工艺试验;分析了材料的去除机理。试验结果表明:金刚石微粉的抛光效果最好;金刚石微粉磁流变超声复合抛光陶瓷滚子1h的表面粗糙度Ra约为0.025μm;超声振动对陶瓷滚子抛光的材料去除率和表面质量有提高作用;材料去除过程主要是机械剪切力作用。     

医用钛合金海尔贝克磁场阵列化学磁流变抛光研究

为了提高医用钛合金（TC4）抛光中的精度以及效率,采用基于海尔贝克磁场阵列的化学磁流变抛光方法加工医用钛合金. 利用海尔贝克磁场阵列强化磁场强度,将过氧化氢溶液作为氧化剂来进行抛光加工. 通过仿真模拟对比海尔贝克磁场阵列与常规N-S磁场阵列,改变羰基铁粉的活性来验证实验可行性,研究了加工间隙、主轴转速以及磨粒粒径对工件表面粗糙度以及接触角的影响规律. 结果表明,海尔贝克磁场阵列比常规N-S磁场阵列有更高的磁场强度;采用本文方法抛光的医用钛合金表面粗糙度比单一纯磁流变抛光降低80%;当加工间隙为0.8 mm,主轴转速为400 rad/min,磨粒粒径为1 μm时,可使工件表面达到光滑效果,表面粗糙度最优可达15.5 nm,同时测量出实验组钛合金表面接触角数值多数小于90°. 应用该方法抛光医用钛合金可以得到超光滑表面,表面具有亲水性,符合医用钛合金标准.     

磁流变抛光轮结构设计与磁场分析

目前对磁流变抛光中磁场的研究主要是进行粗略的评估,并不能实现精确的控制.本文对磁流变抛光中的磁场展开了更为精确的分析.首先设计了磁流变抛光系统,并对其抛光机理进行了阐述;其次对磁流变抛光轮的结构进行了设计,并对其实现方式进行描述;进而利用有限元法对磁流变抛光轮内部磁场进行了具体分析,得到了分布合理的梯度磁场.利用在磁感线上取点进行拟合的方法得到磁感线方程,计算磁感线与磁流变抛光轮表面所围成的面积值,可通过有效控制磁流变抛光液的截面流量使其按照指定磁感线进行分布,完成整个抛光过程,从而为利用磁场控制磁流变抛光液进行确定性抛光提供了保证.     

The Synthetic Effect of Magnetorheological Finishing Technology: Analysis,Modeling,and Control

The controllable key factors in magnetorheological finishing device were studied to determine their influence on efficiency of magnetorheological finishing (MRF) and surface of MRF,as well as interaction between efficiency and surface. Based on theoretical and experimental research,the law of material removal was explored and a new process variable based material removal model (PVMR) was proposed. The experimental findings demonstrate that PVMR reveals the law of the material removal with introduction of three concepts and makes a material removal function z (yi) where the magnetorheological finishing process parameters are considered since they are easy to control and adjust. So the material function of this model is quadratic curve function which is readily suitable for stability and online control magnetorheological finishing.     

Surface roughness and removal rate in magnetorheological finishing of a subsurface damage free surface

Based on computer-controlled optical surfacing, a new technique called magnetorheological finishing (MRF), is presented. The new technique combines the features of conventional loose abrasive machining with a wheel shaped polishing tool. The tool incorporates a host of features and has unprecedented fabricating versatility. The pre-polishing and fine polishing processes can be performed only by adjusting different parameters. The material removal function is studied theoretically and the results of simulation present a Gaussian distribution feature. Based on the established theoretical model, material removal rate experiments involving a parabolic mirror are designed and carried out to determine the effect of controllable parameters on size of the gap between the workpiece and the polishing wheel, rotating speed of the polishing wheel, concentration of volume fraction of non-magnetic particles and polishing time. Further experiments are carried out on the surface microstructure of the workpiece, the final surface roughness with an initial value of 10.98 nm reaches 1.22 nm root mean square (RMS) after 20 min of polishing. The subsurface damage experiment and the atomic force microscopy (AFM) measurement on the polished surface can also verify the feasibility of the MRF technique.     

Surface roughness and removal rate in magnetorheological finishing of a subsurface damage free surface

Asphericalopticalcomponentsareimportantin modernopticalsystems[1].Thereexistmanytypesof aspheres.Thecommonlyusedonesincludeparabola,ellipsoid,etc.[2]Recently,increasingrequirements forasphericalopticalcomponents(e.g.forlithogra phy)togetherwithgrowingfieldsoftheirapplication(e.g.conformalandfreeformoptics)resultina strongneedforopticalfinishingmethodsthatcanbe appliedlocallytopolishcomplexshapedaspheresin brittlematerials(e.g.glass)[3].However,making high precisionaspheresisstillprimarilyanard…     

Magnetic Bingham fluidassisted deterministic polishing for super-smooth surfaces

In order to attain ultrahigh precision optical compo-nents, many optical engineers have adopted computer-controlled optical surfacing technique, which combinesthe characteristics of processes with advanced facilities[1].In particular, magnetorheological f…     

砂轮约束磨粒喷射精密光整加工表面形貌的创成机理

针对磨削加工存在表面缺陷层,重要零件需要在磨削后进行以去除表面缺陷层、降低粗糙度和波纹度等光整加工的实际,提出了砂轮约束磨粒喷射光整加工新工艺,将磨削与磨粒喷射精密光整加工一体化·阐述了表面光整加工的主要方法,研究了砂轮约束磨粒喷射精密光整加工材料去除机理和微观表面形貌的创成机理,在楔形区游离磨粒获得能量对工件进行抛磨、滑擦、微耕犁和微切削是材料去除机理的核心因素,磨料流体侧向挤出是均化和降低表面波纹度的主要因素·试验表明,该方法能明显去除磨削加工过度塑性变形、降低表面粗糙度和均化波纹度,对丰富精密光整加工工艺和理论具有重要意义,并对工业生产有实用价值·     

6H-SiC晶片集群磁流变研磨工艺优化

为了研究不同种类磨粒与羰基铁粉的粒径匹配性对加工效果的影响规律,并优化磁感应强度、研磨压力、研磨盘转速和工件转速等工艺参数,采用集群磁流变研磨方法对6H-SiC晶片进行了研磨试验。结果表明:当磨粒与羰基铁粉的粒径比约为1.5时加工效果较好;各工艺参数对6H-SiC加工的材料去除率的影响由大到小依次为磁感应强度、研磨盘转速、研磨压力、工件转速,对表面粗糙度的影响由大到小依次为磁感应强度、研磨压力、工件转速、研磨盘转速;磁感应强度可以改变羰基铁粉的吸附力,从而改变对磨粒的把持程度,成为影响加工效果最显著的因素。优化后的工艺参数组合为:工件转速60r·min-1;研磨盘逆向转速90r·min-1;研磨压力70kPa;磁感应强度0.012T。在此优化条件下能获得最大的材料去除率(0.498μm·min-1)和较低的表面粗糙度(86.3nm)。     

磁性研磨的加工特性

磁性研磨是一种利用磁场中的磁性磨料对具有相对运动的工件表面进行光整加工的新技术，具有表面质量好、适应性能广泛的优点。     

Viscosity behavior of magnetic suspensions in fluid-assisted finishing

Magnetic fluid-assisted finishing has been verified both theoretically and experimentally as an effective fabrication technology for optical mirrors and lenses. The purpose of this paper is to introduce a novel design of polishing tool and demonstrate the possible applications of this technology. The work includes studying the viscosity of the magnetic suspensions of micrometer-sized Carbonyl iron particles under the influence of a magnetic field. Both the cases of magnetizable suspension with and without abrasive cerium oxide particles are studied for their ensuing polishing effectiveness. Determination of material removal function is conducted using a Wyko Nat1100 interferometer. Experiments to reduce surface roughness with the proposed tool are also performed using a K9 mirror as the work-piece. Results show that the surface accuracy is improved over three times to less than 0.5 nm after two cycles of polishing.