液体磁性磨具光整加工TC4钛合金的试验研究

为解决TC4钛合金材料难加工问题,采用液体磁性磨具对TC4钛合金进行了表面加工试验。通过调整工艺参数,采用田口方法对TC4钛合金液体磁性磨具光整加工的工艺参数进行优化。采用单因素试验法,研究磨料类型、磨料粒径、工件转速和电流强度等工艺参数对液体磁性磨具光整加工TC4钛合金材料加工性能的影响,并总结各工艺参数对工件表面粗糙度的影响规律。根据信噪比的望大特性分析得出,在液体磁性磨具光整加工TC4钛合金材料的加工过程中,当使用2 000目的白刚玉,主轴转速为500 r/min,电流强度为1.5 A加工时,工件表面粗糙度相对下降率%ΔRa达到了86.10%。液体磁性磨具光整加工TC4材料表面的最优工艺参数组合为:2 000目的白刚玉,主轴转速为700 r/min,电流强度为2.0 A。同时得出各工艺参数对工件表面粗糙度相对下降率%ΔRa的影响大小依次为:磨料类型磨料粒径工件转速电流强度。当采用2 000目的白刚玉配置的磨料进行加工时,工件的表面粗糙度Ra达到了0.096μm。采用液体磁性磨具光整加工技术可以有效地降低TC4钛合金材料的表面粗糙度和提升其工件表面加工质量,显著改善了传统加工方式中存在的烧蚀和烧伤现象。     

固着磨料加工碳化硅反射镜的材料去除率及表面粗糙度的理论研究

本文基于固着磨料加工碳化硅反射镜的微观作用原理，理论上定量分析探讨了金刚石磨料压入碳化硅工件的深度对材料去除率、光学元件表面粗糙度的影响，分别获得了材料去除率数学模型及粗糙度的仿真计算结果。通过去除率及粗糙度的实验与理论模型的对比结果来看，实验值虽与理论值有偏差，但基本稳定在同一数量级内，由此验证了理论分析的正确性。固着磨料工艺的这一易于理论预测的特性对实际的光学加工有着极为重要的意义，因此这种较为新颖的固着磨料工艺在碳化硅反射镜加工领域内有着广阔的应用前景。     

弹性磨具磨抛SKD11钢磨损抑制与参数优化研究

SKD11钢是一种用于军工设备导弹架关键零件的特殊难加工材料,其服役表面需达到镜面级粗糙度,该材料淬火后高硬度特性使传统磨抛方式费时费力。为实现工件表面高效磨抛加工,采用弹性磨具进行曲面磨抛加工实验,建立弹性磨具曲面磨抛模型,研究加工参数对材料去除率和磨具磨损的影响规律,利用田口法和灰色关联分析实现材料去除率、磨耗比和表面粗糙度的多目标参数优化,并通过实验验证优化参数可靠性。结果表明:设定切深和磨具转速是材料去除率和磨具磨损的主要影响参数,在保证磨具寿命前提下设定切深应小于0.3 mm,磨具转速低于9 000 r/min;优化参数组合为粒度#320,磨具转速3 000 r/min,设定切深0.3 mm,进给速度2 mm/min,优化后工件平均表面粗糙度Ra降至0.056μm,材料去除率提高2.6倍,磨具磨损有所改善。     

固着磨料加工碳化硅反射镜的初步实验研究

本文采用了一种有别于传统的加工碳化硅反射镜的工艺---固着磨料加工工艺。此工艺不但可以利用大颗粒金刚石磨料快速加工出较好的镜面质量,而且由于其固着磨料与工件相对运动关系固定,有利于精确加工。在工艺实验中,分别测得了W7,W5,W3.5,W1.5固着磨料丸片在特定转速和压力下对碳化硅材料的去除特性。通过多组去除量曲线,我们得出此工艺不仅有着较高的去除率,而且其稳定性非常良好。另外在表面粗糙度结果方面,最初使用W7丸片获得了粗糙度为42.758nm rms的镜面。我们不断减小所用丸片的粒度,工件表面粗糙度随之减小。在使用W1.5丸片抛光后,最终获得了粗糙度为1.591nm rms的光滑镜面。实验结果表明,固着磨料加工碳化硅反射镜工艺在某些加工阶段内可以取代传统的散粒磨料加工工艺,有着良好的应用前景。     

平面研磨中基于磨具均匀磨损的磨具设计方法研究

首先详细地分析了固着磨料平面高速研磨中磨具均匀磨损的条件以及影响磨具均匀磨损的因素,然后根据磨具均匀磨损理论研究了磨具的设计方法和步骤,最后对按照这种方法设计出的磨具进行了使用验证。结果表明,采用这种方法设计的磨具在加工硬脆材料时,可以很容易地获得纳米级表面粗糙度的光滑表面,如在加工常压烧结SiC陶瓷密封环时,加工表面粗糙度可达2-3nm,平面度小于0.8μm:而且,加工效率高,成本低,磨具和加工工件都能在较长时间内保持较好的面形精度,非常适合于大批量工业化生产。     

固着磨料加工碳化硅反射镜的实验

考虑固着磨料加工工艺其固着磨料与工件相对运动关系固定,有利于精确加工,提出了采用该工艺加工碳化硅反射镜的方法,利用大颗粒金刚石磨料快速加工出了较好的镜面质量.在工艺实验中,分别测得了W7,W5,W3.5,W1.5 固着磨料丸片在特定转速和压力下对碳化硅材料的去除特性.对多组去除量曲线的分析表明,此工艺不仅有着较高的去除率,而且稳定性良好.对表面粗糙度测量的结果表明,使用W7丸片即可获得粗糙度为42.758 am rms的镜面.减小所用丸片的粒度,工件表面粗糙度随之减小,使用WI.5丸片抛光后,最终获得了粗糙度为1.591 nm rms的光滑镜面.实验结果表明,固着磨料加工碳化硅反射镜工艺在粗研、精研、粗抛等加工阶段内可以取代传统的散粒磨料加工工艺.     

铝合金阳极氧化膜的集群磁流变平面抛光试验研究

为获得抛光均匀的铝合金阳极氧化膜表面,采用集群磁流变平面抛光技术对铝合金阳极氧化膜进行抛光试验,探讨加工间隙、工件转速、抛光盘转速、偏摆幅度、加工时间等加工参数对其表面粗糙度和材料去除率的影响规律。结果表明:随着加工间隙的增大,工件表面粗糙度先减小后增大,材料去除率则递减;随着工件转速或偏摆幅度的增加,工件的表面粗糙度均先迅速减小后缓慢增大,材料去除率则先增加后减小;随着抛光盘转速的增加,工件的表面粗糙度和材料去除率均先减小后增加;随着加工时间的延长,表面粗糙度迅速减小之后趋于稳定。在文中试验条件下,在加工间隙1. 1 mm、工件转速350 r/min、抛光盘转速60 r/min、偏摆幅度10 mm、加工10 min左右时工件表面粗糙度从原始的332. 9 nm下降至5. 2 nm,达到了镜面效果。     

抛物面研磨的材料去除率及表面粗糙度研究

固着磨料抛物面研磨是一种新型的抛物面加工方法,文中从单个磨粒的角度出发,讨论了研磨工艺参数对材料去除率和表面粗糙度的影响,建立了理论预测模型,然后利用计算机辅助软件对不同硬度工件材料的材料去除率和表面粗糙度进行了数值模拟仿真,最后用实验验证了模型的正确性,并得出结论:理论预测模型仅能预测材料去除率和表面粗糙度的变化趋势,并不能代替实验得出具体的实验数值,即固着磨料抛物面研磨的材料去除率与主轴转速、研磨压力的5/4次方成正比,与磨粒浓度的1/4次方成反比;表面粗糙度随磨粒尺寸和研磨压力的增加而增加,随磨粒浓度的增加而减小。     

研磨压力对固结聚集体磨料垫自修正影响

固结磨料研磨过程中磨料的微破碎是实现固结磨料垫自修正特性的主要途径,研磨压力是影响磨粒微破碎的关键参数。选用单晶金刚石和聚集体金刚石作为磨粒制备固结磨料垫,在15 kPa压力下以石英玻璃为加工对象进行研磨实验,比较两者的材料去除率及加工稳定性;制备了4种陶瓷结合剂含量的聚集体金刚石,并制备成固结聚集体金刚石磨料垫,探索了不同压力下的固结聚集体金刚石磨料垫的自修正性能;分析了研磨后的工件表面粗糙度和表面微观形貌。结果表明:采用固结聚集体金刚石磨料垫,研磨后工件表面粗糙度低,去除效率稳定;在15~21 kPa的压力下,结合剂含量次高的聚集体金刚石研磨效率高,材料去除率达到8.94~12.43μm/min,加工性能较稳定,研磨后的工件表面粗糙度R a在60 nm左右;在3.5~7 kPa压力下,结合剂含量次低的聚集体金刚石研磨性能较稳定,材料去除率在2.67~3.12μm/min,研磨后的表面粗糙度R a在40 nm左右。高结合剂含量的聚集体金刚石磨粒更适合高研磨压力条件,而低结合剂的聚集体金刚石磨粒更适合于低研磨压力。     

不同粒径金刚石固结磨料抛光硫化锌晶体研究

磨粒粒径是影响抛光最重要的参数之一,是决定加工效率和工件表面质量的关键要素。采用1~3μm、2~4μm、3~5μm 3种粒径的金刚石固结磨料抛光垫加工硫化锌晶体,分析磨粒粒径对工件表面质量和材料去除率的影响。实验结果表明,磨粒粒径对硫化锌晶体的固结磨料抛光影响显著,随着磨粒粒径的增大,固结磨料抛光硫化锌晶体的材料去除率增大,而表面质量变差。2~4μm金刚石固结磨料抛光垫加工硫化锌晶体可同时获得高材料去除率和优表面质量,材料去除率达到100 nm/min,表面粗糙度为4.37 nm。     

磨粒辅助EDM与ECM复合加工技术

微机电系统(Micro electromechanical systems,MEMS)的快速发展与产品微型化的发展趋势对微细结构表面(包括微孔、微槽和微棱柱/锥等)的加工质量提出了更高的要求,为了提高微细结构表面的加工质量,提出一种磨粒辅助放电加工(Electrodischarge machining,EDM)与电化学加工(Electro chemical machining,ECM)复合加工新方法,通过建立微加工模型分析了该方法的加工机理,搭建了微加工试验平台,并进行了工艺参数优化研究,采用直径500μm和75μm的钨电极在SUS 304不锈钢上分别进行了微盲孔和微通孔加工试验研究,结果表明,在所用的EDM、EDM与ECM复合加工和磨粒辅助EDM与ECM复合加工三种方法中,磨粒辅助EDM与ECM复合加工方法获得的表面粗糙度(Ra15 nm)最高,因此该方法是微细结构表面高效和高质量加工的最佳方法之一。     

SUS304不锈钢ELID镜面磨削正交化实验研究

SUS304不锈钢具有高耐腐耐磨性和良好的综合性能而被广泛应用,但其高韧性和低导热性使传统的SUS304不锈钢磨削或车削工艺存在一定困难。在线电解修整ELID(Electrolytic in-process dressing)磨削技术能有效地用于SUS304不锈钢镜面磨削加工。本文主要对SUS304不锈钢进行ELID镜面磨削正交化实验研究以获得合理的工艺参数。首先利用#325砂轮进行7个影响因素2水平的正交磨削实验,获得初步的优化参数,然后利用#1200砂轮进行3个影响因素2水平的正交镜面磨削实验。通过改变削件砂轮转速、X和Y平台移动速度、进给率和ELID电源件等各种磨削条件,获得优化后的磨削工艺参数,进行了相应的磨削验证,并讨论了工艺参数对磨削特性的影响。研究了不同砂轮磨粒对表面粗糙度的影响,使用#8000金刚石砂轮对SUS304不锈钢镜面磨削,获得表面粗糙度Ra=3.6 nm。     

Experimental Evaluation of Friction and Wear Properties of Solid Lubricant Coatings on SUS440C Steel in Liquid Nitrogen

The friction and wear properties of the prevailing different solid lubricant coatings (Ion-plated Au, Ion-plated Ag and RF-sputtered PTFE on SUS440C stainless steel) used in the bearings of high-speed cryogenic-turbo-pumps of liquid rocket engines were experimentally evaluated in liquid nitrogen immersed conditions. Also the above experiments were carried out with two newly proposed solid lubricant coatings of sputter-ion-plated MoSTi and a new ion-plated Pb on SUS440C stainless steel. The friction coefficient and wear rates of the coatings of ion-plated Au, ion-plated Ag, RF-sputtered PTFE, the new ion-plated Pb and MoS₂Ti-SIP (with coating thickness of 0.7±0.1 μm) on SUS440C steel against SUS440C stainless steel ball in liquid nitrogen were compared. Worn surfaces were examined microscopically with a microscope and a profilometer for understanding the mechanisms of friction and wear and transfer film lubrication in liquid nitrogen. It is found that the newly proposed solid lubricant coatings are showing promising results for their use in liquid nitrogen immersed conditions. The sputter-ion-plated MoSTi coating on SUS 440C steel shows a minimum value of friction coefficient (μ=0.015) and wear rate (w_c=0.56 × 10⁻⁶ mm³/N m ) in liquid nitrogen.     

Two-dimensional vibration-assisted magnetic abrasive finishing of stainless steel SUS304

Traditional magnetic abrasive finishing (MAF) involves unidirectional polishing of surface but suffers the drawback of forming deep scratches, resulting in poor surface quality. This study attempts to enhance the polishing efficiency of MAF by adding vibration to the platform, focusing on the fabrication of the two-dimensional vibration-assisted MAF (2D VAMAF) setup. Experiments are conducted with variations in parameter levels of 2D VAMAF. Comparison of finished surface results shows superiority of 2D VAMAF in obtaining lower surface roughness and mirror surface quality. In addition, this study uses the Taguchi experimental design method to obtain the optimal parameter combination of 2D VAMAF for surface roughness improvement. The optimal combination obtained includes working gap (1 mm) and weight of SiC, steel particles, and machining fluid (1 g, 1.5 g and 3 g, respectively); frequency of vibration along X and Y directions (16.67 Hz); rotational speed of magnet (500 rpm); and size of SiC and steel particles (8000 and #120, respectively). With 5-min 2D VAMAF under optimal parameter combination, the surface roughness of a stainless steel SUS304 workpiece can be reduced from 0.13 to 0.03 μm, an improvement of 77 %. Experimental results reveal that 2D VAMAF can indeed improve surface quality with a shorter processing time and a smaller amount of abrasives required, both of which contribute to cost reduction. With less pollution incurred, 2D VAMAF is a more environmental friendly machining method in industry.     

Basic observations in the flat lapping of aluminum and steels using standard abrasives

This research studies the characteristics of aluminum 2024, 304 stainless steel, and 1018 steel during lapping with three different types of abrasives, namely, garnet, silicon carbide, and white aluminum oxide, through detailed experimental analysis. Specifically, the effects of different abrasives on material removal rate and surface finish were evaluated. It was found that silicon carbide and white aluminum oxide abrasives removed more material per minute than garnet. A higher mean frictional force and mean coefficient of friction were obtained in aluminum lapped with SiC and white Al₂O₃ abrasives, and a lower mean frictional force was obtained in 304 stainless steel lapped with SiC. From geometric and energy-dispersive spectroscopy analysis obtained using scanning electron microscopy, it was confirmed that some abrasives became embedded into the lapped metal substrates. No burn was observed on the lapped samples, and scratches and unfinished lapped parts were observed mainly in 304 stainless steel. In order to determine the quantitative influence of each variable, an analysis of variance was performed. It was found that the main effects of abrasive types, size of abrasives, and type of work material had statistically significant influence on material rate and surface finish. In addition, there was a highly significant two-way interaction between abrasives and workpiece.     

Study of magnetic abrasive finishing in free-form surface operations using the Taguchi method

This study employed magnetic abrasive finishing (MAF) to conduct free-form surface abrasion of stainless SUS304 material operations. The operations were demonstrated using a permanent magnetic finishing mechanism installed at the CNC machining center. The operations were performed using the Taguchi experimental design, considering the effects of magnetic field, spindle revolution, feed rate, working gap, abrasive, and lubricant. Furthermore, the experimental data was collected using the Taguchi experimental design. The optimal parametric conditions for processing stainless SUS304 material were applied in a two-stage process comprised of rough finishing that involved MAF followed by a precise finishing of the surface. Prior to rough finishing, the R_max value was 2.670 μm; after rough finishing, the value was 0.158 μm. Precise finishing yields an even lower value of 0.102 μm similar to that of the mirror surface. Therefore, the results revealed that MAF provides a highly efficient way of obtaining surface finish.     

LD模具钢数控磁性研抛工艺参数的实验研究

讨论了数控磁性研抛工艺在LD新型模具钢上的使用情况.通过实验,分析了磁感应强度、工作间隙、加工时间等工艺参数对研抛效果的影响.实验表明此工艺是一种高效率、高精度和高可靠性的自动化加工方法,有很好的市场前景.     

蜂窝状结构半固结磨料研磨盘的制备及应用

针对传统半固结研磨盘由于盘面较软使得加工衬底面形精度难以保证的问题,提出一种蜂窝状结构的半固结磨料研磨盘的设计与制备方法。该研磨盘采用环氧树脂蜂窝结构作为支撑“骨架”,减小研磨盘的变形,以保证研磨衬底的面形精度,同时采用含有金刚石磨粒的凝胶体作为半固结研磨介质实现对衬底的研磨加工,获得了较好的衬底表面质量。基于该原理制备了一套新型研磨盘,并用于蓝宝石衬底的双面研磨加工。试验结果表明,研磨后衬底表面粗糙度较小,表面划痕和裂纹少,能够获得较好的表面质量;相应地,研磨后蓝宝石衬底的面形精度不仅没有变差,反而得到很大的改善,研磨后衬底的翘曲度、弯曲度和总厚度偏差均大幅减小。另外,研磨效率也相对较高,材料去除率可达0.3～0.4 μm/min。试验结果证明了该新型结构研磨盘不仅可以获得较好的表面质量和较高的研磨效率,同时还可提高衬底的面形精度,可用于面形精度要求较高的薄片衬底零件的精密研磨加工。     

Effects of finishing in abrasive fluid machining on microholes fabricated by EDM

This research investigated the effects of the fine-finishing process on microholes in abrasive fluid machining (AFM). Microholes on stainless steel (SUS 304) and titanium alloy (Ti-6Al-4V) plates were fabricated using a deep drilling machine of electrical discharge machining (EDM) prior to AFM. In the experiment, the Taguchi method was adopted to explore the effects of the machining parameters associated with AFM on the experimentally observed values, such as the material removal rate (MRR) and differences between the dimensions of the entrance and the exit of the microhole. Furthermore, the improvement in the shape precision of the microhole fabricated by EDM and subsequently fine-finished by AFM was also elucidated by using a scanning electron microscope (SEM). The significant machining parameters and the optimal combination levels of the machining parameters were identified by analysis of variance (ANOVA) and the S/N (signal-to-noise) ratio response graph obtained from the analysis of the experimental data.     

不锈钢的磨削加工与电解磨削复合加工比较

根据不锈钢的物理力学特性、不锈钢表面的工作特点和不锈钢表面加工特点,比较磨削加工和电解磨削复合加工二者的加工精度、表面粗糙度和生产率。经过理论分析和试验,选择电解磨削复合加工做为加工不锈钢表面的加工方法,生产的不锈钢表面粗糙度达到了产品质量要求。