磨粒流抛光阀块内孔道的数值模拟与试验研究

针对液压阀块孔道内部结构复杂难以进行精密加工的问题,提出利用磨粒流精密抛光技术来实现加工工艺。使用流体仿真软件Fluent进行数值模拟,研究进口压力、磨料浓度、磨粒粒度等对磨粒流加工效果的影响。以液压阀块内的孔道为研究对象,对不同的进口压力、磨料浓度、磨粒粒度下内孔道磨粒流的速度、湍流动能、静压、壁面剪切力进行仿真,得出结论：当入口压力为8 MPa、磨料浓度为0.1、磨粒粒度为200目时,阀块内孔道的抛光效果较好。以该参数进行相应的磨粒流加工实验,结果表明：阀块孔道内壁面的表面粗糙度明显降低,提高了孔道内壁面的表面质量。     

Dynamic multiphase modeling and optimization of fluid jet polishing process

Fluid jet polishing is a machining process used increasingly in the ultra-precision manufacture of optical components and replication molds. While the process bears some similarities with abrasive water jet machining, it operates at much lower pressure and grit size. This paper presents a computational fluid dynamics model based on latest multiphase turbulent flow computational methods, simulating dynamically the interface between fluid and air. The model is then used to optimize surface texture performance down to 1 nm Ra on electroless nickel plated optical dies, while removing diamond turning marks. Some conclusions are drawn regarding the nature of the removal mechanism.     

磨料射流表面抛光研究综述

作为精密超精密光学制造工艺过程中的一个重要环节,各种新型表面抛光方法与工艺始终吸引着科研人员不断深入研究与探索。磨料射流抛光方法为小型复杂零件的表面抛光提供了一个新思路,成为精密超精密光学加工技术的重要组成部分。对磨料射流表面抛光过程中衍生的磨料水射流抛光、磁射流抛光、负压吸流抛光、磨料气射流抛光、冰粒水射流抛光、纳米胶体射流抛光的抛光原理、方法及特点进行了综述,分析了各射流表面抛光技术材料去除的最新发展;从加工原理、磨料选择、抛光精度、数学模型等方面对上述新型射流抛光技术进行深入分析与比较,其中磁射流抛光、纳米胶体射流抛光、磨料水射流抛光的抛光精度较高,可以实现表面粗糙度纳米级的超精密抛光,而磨料气射流抛光、冰粒射流抛光从加工成本上来讲则相对较低。最后,对磨料射流表面抛光在去除函数优化、精度效率的提高、应用范围扩展、在线检测、商业化应用等方面的发展趋势进行了预测。     

Finishing effects of spiral polishing method on micro lapping surface

This study presents a spiral polishing method and a device for micro-finishing purposes. This novel finishing process has wider application than traditional processes. This offers both automation and flexibility in final machining operations for deburring, polishing, and removing recast layers, thereby producing compressive residual stresses even in difficult to reach areas. Applying of this method can obtain a fine polished surface by removing tiny fragments via a micro lapping generated by transmission of an abrasive medium through a screw rod. The effect of the removal of the tiny fragments can be achieved due to the function of micro lapping. The method is not dependent on the size of the work-piece's application area in order to carry out the ultra precise process. The application of this research can be extended to various products of precision ball-bearing lead screw. The proposed method produces products with greater precision and more efficiently than traditional processes, in terms of processing precisions and the surface quality of products. These parameters used in achieving maximum material removal rate (MRR) and the lowest surface roughness (SR) are abrasive particle size, abrasive concentration, gap, revolution speed and machining time.     

增材制造金属零件抛光加工技术研究进展

金属增材制造在航空航天、医用植入等领域有良好的应用前景,但成型表面质量差,未经后处理加工无法满足高使役性要求,抛光加工是高性能金属增材制造技术链中的关键环节。概述了增材制造金属零件应用现状和生长过程固有的阶梯效应、球化效应、粉末粘附等特性,以及成型表面高粗糙度等形貌特征。在此基础上,重点综述了增材制造金属零件抛光加工中应用较广的电化学、激光、磨料流三种抛光技术的研究进展,以不同制造工艺、不同金属粉末材质、不同结构形式(多孔结构、高长径比流道等)的增材制造样件为主线,通过表面粗糙度、材料去除、表层残余应力、廓形精度保持性等技术指标,对增材制造金属零件抛光加工研究成果进行了归纳总结。最后展望了增材制造金属零件抛光技术的发展方向。     

高速磨粒流动辅助电解复合加工方法

针对难加工材料表面抛光难、工具损耗严重、加工效率低的问题,提出了一种高速磨粒流动辅助电解加工的方法,通过在电解液中添加微小磨粒,伴随电解液高速流动实现电化学溶解与钝化膜微量磨削的复合加工。针对该方法的加工参数进行了分析,研究了加工时间、加工电压、加工间隙、电解液浓度、电源种类、磨粒粒径对实验结果的影响。结果表明:采用5 V电压的直流电源,以质量分数10%的NaNO3作为电解液,设定加工间隙1 mm,用1200目的磨粒加工5 min,可得到表面质量较好的工件,表面粗糙度Ra<0.1μm。     

Study on the characteristics of Magneto-Electrolytic-Abrasive Polishing by using the newly developed nonwoven-abrasive pads

Recently, advanced technologies in general industry demand that the production of precision parts is much more precise and efficient. However, most of the precision finishing technologies cannot satisfy both the finishing efficiency and surface finishing at the same time. Magneto-Electrolytic-Abrasive Polishing (MEAP) is a new ultra precision machining technology, which combined many kinds of energy, has been deeply investigated under this urgent demand and its effect has been much improved. The method of MEAP for those difficult-to-cut materials has become an important technique in the precision machining field. In particular, the nonwoven abrasive pad, which is a kind efficient matching polishing material used in MEAP system, has been developed. Because nonwoven abrasive pads can cut off the oxide membrane which appears during electrolytic polishing process without time delay and there are no scratches left on workpiece surface, it has been proved that it is a high efficiency and economic polishing material. In this study, the basic properties of nonwoven abrasive pads have been explained and the developed processes for SiC and Al₂O₃ nonwoven abrasive pads have also been described. Their polishing abilities on difficult-to-cut materials of Cr-coated rollers have been tested according to different kinds of pad. Through using the life test experiment, their economic benefits in Magneto-Electrolytic-Abrasive Polishing systems will be discussed.     

Experimental study on abrasive waterjet polishing for hard–brittle materials

The rapid growth of hard–brittle materials necessitates the development of compatible machining techniques, especially for the precision machining. The abrasive waterjet (AWJ) machining is a powerful tool in processing hard–brittle materials. In the last decades, some of AWJ machining technologies, such as AWJ cutting, AWJ milling and AWJ drilling have gradually become mature and steady. However, a few investigations on precision surface machining for hard–brittle materials by AWJ had been carried out. In this research, the ductile erosion mechanism of hard–brittle materials by AWJ in small erosion angle has been analyzed. In theory, the ductile erosion can achieve micromaterial removal and the surface eroded is smooth and without any fracture. Based on the ductile erosion mechanism, the feasibility of polishing for hard–brittle materials by the AWJ has been investigated. A group of polishing experiments is performed. The polished surfaces of workpieces were observed with scanning electron microscope (SEM) and measured by atomic force microscopy (AFM). The results of these polishing experiments indicate that AWJ has a great potential to be used as a precision surface machining technology.     

A comparative study: polishing characteristics and its mechanisms of three vibration modes in vibration-assisted magnetic abrasive polishing

The automatic precision polishing technique of three-dimensional complicated micro-curved surfaces of components in extremely low surface roughness and high efficiency is greatly demanded by advanced industrial fields. The existing polishing methods have great difficulty in satisfying these demands. Therefore, three modes (horizontal vibration, vertical vibration and compound vibration) of vibration-assisted magnetic abrasive polishing processes have been developed. Previous research focused on each polishing characteristic. The aims of this paper are to characterize effects of vibration of workpiece on magnetic field, polishing pressure, in-process abrasive behavior and polishing performances in three vibration modes and to describe their machining mechanism. Furthermore, a realization of efficient polishing of a 3D micro-curved surface was confirmed to be possible by the process.     

Polishing of fiber optic connectors

The polishing characteristics of end faces of fiber optic connectors consisting of the combined structure of silica inlaid zirconia were investigated using a connector polisher and polishing papers with different abrasive types and grit sizes. The geometrical quality was measured using optical interferometry and fiber optical microscopy. The quality parameters included fiber and ferrule surface roughness, end face morphology, fiber height, radius of curvature, and apex offset. The optical performance was eval uated in terms of return and insertion losses using a loss tester. The surface roughness smaller than 20 nm R_a in the fiber area, the fiber heights smaller than 75 nm, the end face curvature radii of about 20–50 mm, and the apex offsets smaller than 100 μm were obtained in a polishing cycle of 1 min. The corresponding average return and insertion losses of −48 and 0.15 dB, respectively, were also achieved. The polishing efficiency was raised by at least 30% compared to the commercially applied processes. Finally, the polishing mechanisms of the fiber optic connectors were investigated regarding material response to abrasive machining.     

微小非球面碳化钨光学模具的磁流变抛光特性研究

超精密加工是光学模具获得高形状精度、表面精度和表面完整性的必要手段。通过实验比较抛光前后工件面形精度的PV值及RMS值来研究微小非球面碳化钨光学模具的磁流变抛光特性。结果表明:磁流变抛光技术对提高微小非球面碳化钨光学模具形状精度、表面精度等有较显著的作用。     

A study on polishing of molds using hydrophilic fixed abrasive pad

The finishing process for die and mold manufacturing is very important because it influences the final quality of the products. injection molds especially need higher quality surface than general purpose dies and molds. Conventional polishing cannot reduce mold surface down to nanometer roughness efficiently because of loading and glazing. This paper focussed on the development of a fixed abrasive pad using the water swelling mechanism of polymer binder network. Self-conditioning was recognized as a long term polishing stabilization tool without any loading or glazing because water makes the fixed abrasives free by the swelling of the pad. Consequently, a stable nanopolishing process has been realized on the injection mold, based on the experimental results with a polished surface roughness of R_a 15.1 nm on D2 die steel (AISI standard).     

磷酸二氢钾晶体的立轴端面可磨性研究

磷酸二氢钾（potassium dihydrogen phosphate,KDP）晶体是公认的性能优良的光学晶体,尤其是大口径（≥ 400 mm）的KDP晶体,是激光核聚变中不可缺少的光学元件之一。KDP晶体从生长到制造成为光学元件,需要经过切割、精密加工、超精密加工及镀膜等多道工序,加工周期长。本研究通过立轴端面磨床对KDP晶体进行磨削加工试验,对比不同粒度的树脂结合剂金刚石砂轮（D7、D36、D91、D151）,在不同的加工参数下（主轴转速、工件进给速度、磨削切深）,对表面粗糙度R_a、表面微观形貌的影响,研究KDP晶体磨削的可行性,为实现以磨代车（抛）,缩短KDP光学晶体元件制造周期奠定基础。      

空间基础零部件超精密抛光技术研究进展

轴承、齿轮、陀螺仪谐振子、反射镜等是实现航天器旋转支撑、动力传递、姿态控制、空间探测等功能的核心基础零部件,直接影响航天器的性能、寿命和可靠性。为了确保航天任务顺利进行,空间基础零部件必须拥有优异的使役性能、高的可靠性和长的寿命,其工作面的状态是关键影响因素。为此,基于制造角度,必须不断提高工作面的精度和表面质量。然而,空间基础零部件的工作面多为复杂曲面,且材料包含多种元素和金相组织,可控抛光难度大。从轴承、齿轮、陀螺仪谐振子、反射镜等4种空间基础零部件的特点出发,简要陈述了各自的超精密抛光需求及必要性,分类总结了现有的超精密抛光技术,如应用于轴承的双盘研磨抛光、电化学机械抛光、流变抛光,应用于齿轮的磨粒流抛光、流变抛光、电化学机械抛光,应用于陀螺仪谐振子的流变抛光、飞秒激光和离子束质量调平,以及应用于反射镜的磁流变抛光、计算机控制光学表面成型、气囊抛光、离子束修形抛光等,阐述了各种抛光技术的原理和效果,最后展望了超精密抛光技术的发展方向,以期为空间基础零部件的超精密加工提供借鉴。     

自动式圆形弯管内表面精密抛光装置设计

为了解决弯管内表面精密抛光困难的问题,设计了一种弯管内表面自动抛光装置。该抛光装置总体结构由抛光头、绕线机构、传动机构、夹紧机构以及连接机构等部分组成。整个装置与圆截面弯管零件连成一容腔,可向零件内腔充入用于对零件内表面进行抛光加工的抛光液,控制器控制步进电机带动两端的绕线装置工作,从而实现对弯管内表面的精密抛光加工。利用软件Fluent进行流体仿真,仿真结果表明:流体出口的流速很高,使旋转喷射抛光作用发挥得较好,能够很好地对圆形截面弯管内表面进行抛光加工。     

Fluid flow analysis of magnetorheological abrasive flow finishing (MRAFF) process

A new precision finishing process called magnetorheological abrasive flow finishing (MRAFF), which is basically a combination of abrasive flow machining (AFM) and magnetorheological finishing (MRF), has been developed for nano-finishing of parts even with complicated geometry for a wide range of industrial applications. This paper deals with the theoretical investigations into the mechanism of MRAFF process to study the effects of various process parameters. In the present work, an attempt has been made to analyze the medium flow through the fixture by finite difference method by assuming the medium as Bingham plastic to evaluate the stresses developed during the process. A capillary viscometer has been designed and fabricated to study the effect of magnetic field on the rheological properties of the medium. Microstructure of the mixture of ferromagnetic and abrasive particles in magnetorheological polishing fluid (MRPF) has been proposed, and normal force on the abrasive particles is calculated from the applied magnetic field. A model for the prediction of material removal and surface roughness has also been presented. Theoretical results compare well with the experimental data available in the literature.     

圆光栅玻璃的游离磨料研磨抛光加工工艺

用游离磨料对圆光栅玻璃表面进行了研磨抛光实验,讨论了磨粒尺寸、磨料质量分数、加工时间、研磨盘转速、加载压力、抛光垫材料对试件表面粗糙度和材料去除率的影响。研究表明,硬质抛光垫能更好地保持试件的平面度。获得的优化工艺参数组合为:研磨盘转速75r/min;磨料质量分数10%;研磨液流量10mL/min;5μm的Al2O3加载压力0.019MPa,粗研20min;1μm的Al2O3加载压力0.015MPa,精研20min;30nm的CeO2加载压力0.012MPa,精抛10min。在该工艺组合下,获得了表面粗糙度值Ra为3.3nm、平面度为5μm的圆光栅玻璃。     

基于ELID磨削WC-Co硬质合金表面机械研抛研究

本文采用ELID磨削和机械研磨抛光复合技术,对WC-Co硬质合金表面进行了超精密加工实验研究。首先采用ELID磨削对WC-Co硬质合金表面进行预加工,获得表面粗糙度Ra18 nm的精密加工表面。在此基础上对其进行机械研磨抛光加工,研抛盘转速设定为150～200 r/min,研抛压力控制在0.2～0.5 N/cm2范围;机械研抛时,首先采用含W1金刚石磨粒的研抛液,对ELID磨削后的表面进行加工100min左右,以达到快速去除的目的。再用含W0.5金刚石磨粒的研抛液,进行机械研抛约100 min,最后获得Ra4 nm的超精密表面。同时,针对机械研磨抛光过程,本文深入研究了磨料种类、粒度、抛光液溶剂、研抛压力、研抛加工时间等因素对加工表面粗糙度的影响。     

抛光垫表面微细结构对抛光性能的影响试验

抛光垫是影响抛光加工效率和表面质量的关键因素之一,但影响规律和作用机理尚不清晰。为研究抛光垫表面微细结构对抛光性能的影响规律,制作有、无固结磨料的表面六边形微细结构抛光垫,分别对YG15硬质合金、单晶Si和单晶4H-SiC三种硬度差异较大的工件进行抛光试验。结果表明：各抛光垫对不同硬度工件抛光效果的影响规律一致,随着抛光工件的硬度增大,各抛光垫的材料去除率（MRR）减小,表面粗糙度Ra增大。抛光垫内的固结磨料能将MRR提高5～10倍,但也会导致Ra增大5～20倍。抛光垫表面微细结构会使得抛光过程中有效接触面积Ap和有效磨粒数Ns减小而导致MRR下降,而抛光垫硬度的增加能够部分弥补抛光垫表面微细结构造成的影响,抛光工件硬度越大,弥补效果越好。增加游离磨料能够有效降低抛光后Ra并提高硬度较大工件的MRR（上升约8%）,但对硬度较小工件的MRR有抑制作用（下降约27%）。根据抛光试验结果,建立工件-磨料-抛光垫接触模型,深入分析抛光垫表面微细结构、表面硬度对不同硬度工件抛光MRR和表面质量的作用机理,为不同工件抛光时抛光垫的选择提供了理论基础。     

磨料尺寸对固结金刚石聚集体磨料垫研磨石英玻璃加工性能的影响

石英玻璃的研磨加工是其超光滑抛光加工的前道工序,对其加工效率和最终表面质量影响甚大。针对石英玻璃的硬脆特性,采用固结金刚石聚集体磨料研磨垫,对其高效低损伤研磨加工工艺进行了研究。探索了金刚石聚集体磨粒的一次颗粒尺寸、二次颗粒尺寸、研磨压力和研磨液流量4因素对研磨石英玻璃加工性能的影响,综合优化得到加工效率高和表面质量优的工艺参数。实验表明:采用固结金刚石聚集体磨料研磨垫,当一次颗粒尺寸和二次颗粒尺寸分别为1.0~2.0 μm和20~25 μm,研磨压力为14 kPa,研磨液流量为60 mL/min时,材料去除率达到2.64 μm/min,平均表面粗糙度值R_a为54.2 nm。