扫描式阴极电化学光整加工对车削外圆面边缘毛刺的去除

目的 通过电化学光整加工,在改善车削零件表面粗糙度的同时,有效去除工件边缘两侧方向的微小毛刺,提高零件表面的完整性.方法 在扫描式阴极电化学光整加工能实现表面良好光整加工效果的参数范围内,通过改变阴极局部形状,改变毛刺部位的电场分布,进而改变其材料去除速度,实现毛刺去除.对不同形状阴极条件下,毛刺表面的电流密度分布及毛刺顶端和底部的电流密度差值进行仿真分析,得到使毛刺高度值下降较快的阴极形状.对工件进行扫描式阴极电化学光整加工,获得表面粗糙度Ra与毛刺高度值的变化规律.结果 使用凸圆角阴极时,毛刺顶端和底部的电流密度差值较大,去除效率较高.Ra值在加工时间为16～18 min时出现拐点,加工20 min时,Ra值由2.76μm降低至0.32μm;毛刺高度值在加工时间为10～14 min时出现拐点,加工20 min时,从17.10μm降低至2.64μm,与表面粗糙度Rz值为同一量级.结论 通过改变阴极形状,在电化学光整加工过程中能有效降低车削工件边缘两侧方向的微小毛刺,实现零件使用性能的提高,具有实际应用中的可行性.     

基于激光束全反射的激光与电解复合小孔加工技术研究

针对高表面质量精密深小孔加工需求,提出了激光与管电极电解复合加工技术(LaserSTEM),利用管电极内激光束全光导效应将激光能量高效传导至加工区域,综合采用激光-材料相互作用、电化学刻蚀及其耦合效应对材料高效去除,实现大深度小孔加工。基于Laser-STEM的加工机理,综合采用几何光学理论计算、光学仿真和试验验证的方法对激光与管电极耦合机制进行了研究,得到了激光功率和加工电压对材料去除速率与加工精度的关系,并利用Laser-STEM技术实现了深度5 mm、直径1.2 mm的小孔高效加工。     

航天发动机壳体类零件电化学去毛刺加工工艺研究

阐述了电化学去毛刺的原理、优点及适用范围.介绍了航天发动机壳体类零件相交孔电化学去毛刺的工艺内容,分析了试验结果.通过合理设计电极,选用合适的电解液温度和加工时间,可将毛刺完全去除.     

纯钼与纯钛电化学去毛刺实验研究

为消除由纯钼和纯钛加工成的待加工件表面出现的金属重熔层和毛刺,选用电化学去毛刺工艺来去除这些待加工件上的金属重熔层和毛刺。电化学去毛刺工艺利用电化学阳极溶解的原理去除间隙的毛刺,其具有对工件无机械力、与工件材料硬度无关等优点因此其在加工高硬度和高韧性的金属工件上有着天然优势。通过使用不同电解液,运用电化学去毛刺的加工手段分别测试用电火花线切割加工过的钼片和钛片的去毛刺效果,得到了在30℃的电解液温度和5V的加工电压以及5s的加工时长下,电化学去毛刺加工在对纯钼和纯钛的加工上有着很明显的效果的结果。     

紫铜电极加工中毛刺产生原因与去除方法

介绍了紫铜电极加工中毛刺产生的原因及其危害、传统去除电极毛刺的方法,详细讲述了采用数控铣加工电极去除毛刺的原理及方法,达到对电极进行优质、高效和经济加工的目的,降低电极加工难度,提高电极加工质量。     

基于CAM数控铣削中倒角技术的研究

在进行零件加工时,为了去除表面锐边毛刺、美观零件表面,往往需要对锐边进行倒角处理。应用倒角刀具进行编程时有手工编程和CAM技术自动编程两种方法,不管哪种方式,都需要考量倒角刀具特性和编程计算方法,尤其是对于浅直面、窄干涉面需要考量刀具直径特性对零件其它表面的干涉,防止过切和报废零件,以及防止损坏刀具。针对数控铣削编程加工零件时的机床倒角编程方法进行了系统研究,在不同的加工部位上选择不同的倒角处理办法。     

电化学去内交叉孔毛刺专用机床电气系统设计

经机械加工后的内交叉孔毛刺大小不一、可达性差,去除较为困难。确定采用从毛刺根部插入加工电极的电化学去毛刺加工方法,分析了电化学去毛刺机床的基本构成及特点,在此基础上对机床的电气系统进行了设计与研究,完成了主电气回路、安全检测系统、控制系统、控温系统的设计及加工电源的选取。该系统具有极间短路检测、安全操作保护、提供温度适合的电解液、按设定参数控制加工过程等功能,具有操控方便,使用安全,可靠性好的特点。     

微细阵列群电极电解加工关键技术研究

提出了基于阴极优化的微细阵列圆柱凸台群电极电化学腐蚀加工法。根据电化学腐蚀基本原理,通过有限元方法分析计算群电极电化学腐蚀加工过程中的电极表面电场分布,以电流密度分布均匀性为目标,优化设计阴极形状,并进行阵列群电极制备。在制备出直径均匀的阵列群电极的基础上,探索用局部涂胶保护法制备大长径比的盘状阵列群电极,用于微细孔电解加工,进一步提高电解加工的定域性。     

电化学射流加工SiC_p/Al复合材料的试验研究

对SiC_p/Al复合材料进行了电化学射流加工试验,探讨材料去除机理,分析加工电压、加工时间对加工形貌及材料去除率的影响。研究发现,材料的去除过程主要包括铝基体的阳极溶解与SiC颗粒的冲刷脱落,SiC颗粒脱落在加工表面形成微凹坑,微凹坑的几何尺寸及数量对加工表面粗糙度具有较大影响;材料去除速率随加工电压的增加而增大,这与电化学射流加工单一金属材料相似。     

薄板小孔的电解加工

在沸腾干燥器的制造中要求在宽1.6米长3.2米厚0.6毫米的不锈钢板上钻直径为0.6毫米的孔150万个左右,要求加工出无毛刺、翻边、倒角、公差在±0.03毫米,内壁光滑的圆孔。我们采用了电解加工的方法。在实验中曾得到南航和北京机床研究所的大力协助,解决了电极、电极绝缘、水保护、加工尾段工艺等几个关键性的问题,分述如下。     

Design of Borer-Rib Type Electrode in Electrochemical Smoothing of Large Holes

This study discusses the electrochemical smoothing and electrobrightening of medium or large holes beyond traditional drilling, boring, turning, or extruding using both inserted and feeding electrodes of borer-rib type for several common die materials. High electrical current is not required when the electrode of borer-rib type is employed to reduce the engaged area for large holes. Traditionally, the hole polishing of a die requires a sequence of complicated premachining or some manual skill. In the current experiment, six types of electrode are completely inserted and connected to both continuous and pulsed direct current, while another six types of electrode are fed into holes using continuous direct current. The design features of the electrodes are of major interest for effective electrochemical smoothing of holes. The controlled factors include the diameter of the electrode as well as the chemical composition and concentration of the electrolyte. The experimental parameters are current density, current rating, electrode design, die material, rotational speed, and feed rate of electrode. For the inserted electrodes, the single-plate electrode performs better than the double-plate electrode, and the single-plate electrode with half borer gives the best polishing effect. Pulsed direct current can slightly improve the polishing effect but at the expense of increased machining time and cost. For the feeding electrodes, the electrode of one-side borer tip with half borer performs the best polishing. It was also found that the electrobrightening after precise boring takes only a short time to make the hole bright, while the electrochemical smoothing saves the need for reaming, making the total processing time less than that required for electrobrightening.     

An analytical model to predict interlayer burr size following drilling of CFRP-metallic stack assemblies

A novel analytical model to describe entrance burr formation when drilling ductile metals as a function of tool geometry (point/helix angles, diameter), operating parameters (cutting speed, feed rate) and workpiece material properties, was initially formulated. The model was further developed to account for interlayer burr dimensions when drilling CFRP-metallic stack arrangements. Data from validation trials performed on Ti–6Al–4V, AA7010 and AA2024 workpieces together with their associated CFRP stack assemblies over 4 different combinations of cutting speed and feed rate showed that the predicted sizes of entrance and interlayer burrs were all accurate to within 20% of the experimentally measured results.     

硼掺杂金刚石电极降解活性橙X-GN偶氮染料废水的研究

目的研究硼掺杂金刚石(BDD)电极电化学氧化降解活性橙X-GN偶氮染料废水。方法采用热丝气相沉积法(HFCVD)制备铌基BDD电极,采用SEM观察BDD薄膜的表面形貌,用Raman检测BDD薄膜的成分,用电化学工作站测试BDD电极的电化学性能。选择活性橙X-GN染料废水作为降解对象,分别研究电流密度(20、50、100、150 m A/cm~2)、电解质浓度(0.025、0.05、0.1 mol/L)和溶液初始pH(3.78、6.74、10.92)等不同工艺参数对降解效率的影响,并采用紫外可见光分光光度计进行测试表征,使用能耗和总有机碳量表征降解效果。结果 BDD电极具有很好的电催化性能,其电势窗口为3.33 V,析氧电位达到2.45 V,远高于大多数有机物的氧化电位,电极表面反应受扩散步骤控制。结合活性橙X-GN染料溶液降解效果,得出100 mg/L活性橙X-GN溶液的最佳降解工艺参数为:电流密度100 m A/cm~2、电解质浓度0.05mol/L、溶液初始pH值3.78。采用最佳工艺参数处理5 h后,色度移除率达到99%,能耗为65.4 k W·h/m~3,TOC去除率达到56.95%。结论 BDD电极可以有效地降解活性橙X-GN染料废水。     

Burr Formation in milling with minimum quantity lubrication

In milling, burrs are formed on entry and exit edges of the workpiece to be machined like in all material removal processes. In the subsequent production these burrs have to be removed. Understanding the influencing factors and burr formation mechanisms can help to avoid or reduce burrs. Another possibility for saving costs is to reduce the process materials, for example, cutting fluids. This can be realised by using minimum quantity lubrication or dry machining. The investigations show which influence both methods have on burr formation.     

GCr15在不同电解液中的加工特性研究

通过测定GCr15轴承钢在质量分数均为15%的NaNO_3、NaClO_3和Na_2SO_4中的极化曲线和电化学阻抗谱(EIS),分析了GCr15钢在低电流密度下的电化学特性。通过测定GCr15钢在大电流密度下的去除量和电流效率,对其一般电解加工特性进行了分析。研究结果表明:阳极极化过程中,三种电解液介质条件下都存在稳定的钝化区,EIS主要表现为容抗弧的变化;NaNO_3与NaClO_3电解液都具有非线性加工特性,能有效提高电解加工的定域性,并减小低电流密度下的杂散电流腐蚀;Na_2SO_4电解液属于线性电解液,加工效率低。     

微细铣削铝合金6061表面毛刺研究

目的揭示微细铣削铝合金6061过程中,铣削工艺参数(切削深度a_p、每齿进给量f_z、切削速度v)、顺逆铣方式、刀具磨损对毛刺大小及形态的影响规律,为控制铝合金6061毛刺,提高表面质量,优化切削工艺提供参考。方法基于单因素试验方法,采用涂层硬质合金微直径铣刀,对铝合金6061进行了铣削加工试验,分别对切削参数单因素试验的逆铣、顺铣顶端毛刺大小数据以及刀具磨损、毛刺形态信息进行采集和分析。结果直观绘制了a_p、v、f_z对逆顺铣两侧顶端毛刺大小的影响规律图。单因素切削速度试验中,顺铣侧毛刺最大为323μm,逆铣侧最大为268μm;单因素每齿进给量试验中,顺铣侧毛刺最大为332μm,逆铣侧最大为331μm;单因素切深试验中顺铣侧毛刺最大为314μm,逆铣侧最大为264μm。结论逆铣比顺铣的顶端毛刺小,随切削深度增加,毛刺依次呈现长条须状、撕裂状、波浪形锯齿状。刀具磨损是造成切削过程不稳定的重要因素,同时也会造成毛刺形态和大小不稳定。为尽量减少毛刺,应采用锋利刀具和逆铣方式,控制切削深度,选择合适的切削速度和进给量。     

Effects of alternating current on corrosion of a coated pipeline steel in a chloride-containing carbonate/bicarbonate solution

In this work, the alternating current (AC)-induced corrosion of a coated pipeline steel was studied in a chloride-containing, concentrated carbonate/bicarbonate solution, which simulated the trapped high pH electrolyte under coating, by potentiodynamic polarization measurements, immersion tests and surface characterization technique. It was found that an application of AC resulted in a negative shift of corrosion potential of the steel, caused an oscillation of anodic current density, and degraded the steel passivity developed in the solution. With the increase of AC current density, the corrosion rate of the steel increased. At a low AC current density, a uniform corrosion occurred, while at a high AC current density, pitting corrosion occurred extensively on the steel electrode surface. At individual applied AC, there was a higher electrochemical dissolution activity of the coated steel electrode containing a 1 mm defect than that of the electrode containing a 10 mm defect.     

Magnetic-Assistance Finishing Processes in Freeform Surfaces

A new finishing process that uses magnetic force with high efficiency to assist discharging dregs from the electrode gap during electrochemical finishing on freeform surfaces is investigated in the current study. The factors affecting electrochemical finishing and the effects of magnetic assistance are primarily discussed. The main experimental parameters are magnetic strength, distance between the two magnets, diameter of the electrode, current density, the on/off period of pulsed current, and rotational speed of the wire electrode. Providing a large magnetic field intensity or using a smaller distance between the two magnets produces a larger magnetic force and discharge efficiency, and results in a better finish. A higher current density with magnetic assistance reduces the finishing time and avoids difficulties in dreg removal. A high rotational speed of the wire electrode produces a better finish. Pulsed direct current can slightly promote the effect of electrochemical finishing, but the current density needs to be higher. Magnetic assistance during the electrochemical finishing process makes a greater contribution in a shorter time making the surface of the workpiece smooth and bright.     

Design of a deburring tool for intersecting holes in aluminum alloys

A deburring tool for intersecting holes is proposed. The tool has a hemispherical cutter head mounted on a pivoted shaft which is loaded against the burr edge by a set of springs. The cutter head is inserted into an intersecting hole up to the burr edge and is subsequently rotated counterclockwise with a return stroke. The cutter head size is selected such that the cutter head has maximum accessibility to the three dimensional burr edge. The cutting edge is designed to maintain proper ranges of rake angle and relief angle during deburring. The efficiency of the tool in terms of deburring speed is verified by a set of deburring tests on Al6061-T6. The measured depth of cut on the burr edge confirms the complete removal of burrs.