数控高效放电铣削加工技术

介绍了我国完全自主原创的数控高效放电铣削加工技术的基本原理.其采用简单超长圆电极,在电极与工件之间施加高效脉冲电源,通过数控系统控制电极与工件的相对运动并对电极损耗进行在线检测和补偿,以类似数控铣的方式加工特殊材料制作的零件复杂形面,实现对特殊难加工材料的高效、低成本加工.并介绍了该加工方法的技术特点、关键技术、设备及应用情况.     

电火花铣削加工用展成电极的设计

为了解决电火花铣削加工中的电极损耗补偿难题,提出了一种基于线电极的电火花铣削加工方法,本文介绍了该方法的加工原理,提出了展成电极的概念及其设计要求,并对展成电极的总体结构、走丝机构、导丝杆的设计给出了较为详细的叙述。实验证明,利用设计的展成电极可在普通数控电火花加工机床上进行基于线电极的电火花铣削加工。     

数控电火花展成加工螺旋曲面整体叶轮

根据锥形水射流钻头螺旋曲面叶轮的几何展成原理，研究了用数控电火花成形机对其展成加工一次成形的方法，讨论了展成加工中存在的电极干涉而导致的过切现象以及成形电极的修正设计方法。     

数控电火花展成加工螺旋曲面整体叶轮

根据锥形水射流钻头螺旋曲面叶轮的几何展成原理，研究了用数控电火花成形机对其展成加工一次成形的方法，讨论了展成加工中存在的电极干涉而导致的过切现象以及成形电极的修正设计方法。     

二维数字化铣刀齿形曲线展成研究

对采用离散数据表述的二维数字化铣刀齿形曲线展成进行研究.根据共轭曲面原理,以二维数字化铣刀齿形曲线的展成加工为例,通过仿真计算,获得实际展成加工中的加工参数和铣刀齿形曲线.该研究完善了传统的解析展成加工理论,并可应用于实际的数字化铣刀的制造与加工工艺.     

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。     

影响电极损耗和使用寿命的因素分析与对策

分析了电火花成形加工中的一些不稳定因素对电极损耗和使用寿命的影响,针对性地提出了合理有效地利用极性效应、面积效应、吸附效应以及对电参数和电极材料的合理选取等措施,为电火花高效低损耗加工、延长电极使用寿命提供了保障.     

紫铜电极负极性加工ZL302基础工艺试验研究

为实现铸造铝合金ZL302的高效电火花加工,在系统试验设计的基础上,进行了紫铜电极负极性加工ZL302的基础工艺试验,获得了材料去除率vm和电极损耗率vE与电参数之间的经验回归数学模型,并依此进行了工艺参数优化.研究结果表明,峰值电流ie、脉冲宽度ti是影响材料去除率vm和电极损耗率vE的主要工艺参数,电压Sv、脉冲间隔t0对材料去除率vm和电极损耗率vE等工艺指标也有影响.试验所得经验回归模型的置信度为95%,可用于指导实际生产.     

基于高速铣削的微细电极加工方法

微模具型腔的高效、高精密加工,一直是制约微模具制造技术发展的瓶颈问题.以微细 电火花加工用的圆柱阵列结构微细电极为对象,研究了应用高速铣削加工技术,实现微细电极的高效、高精密加工方法.通过优化分析微细电极结构和高速铣削加工参数及刀具路径,获得了尺寸和形状精度及表面质量均满足要求的阵列结构微细电极,并以制得的微细电极进行...     

基于流体动力断弧的高速电弧放电加工

提出了一种可用于难加工材料大余量高速蚀除的新的放电加工方法——基于流体动力断弧的高速电弧放电加工。与传统的电火花加工方法相比,高速电弧放电加工采用具有更高能量密度的电弧放电而不是火花放电来实现材料的蚀除;与其他利用电弧进行材料去除的工艺方法相比,高速电弧放电加工可使用特殊设计的成形电极实现强制多孔内充液,从而获得三维复杂型腔的沉入式加工能力,因此具有更广泛的应用前景。初步实验表明,对于镍基高温合金等难切削材料,高速电弧放电加工的材料去除率(MRR)远高于传统的电火花加工,甚至高于铣削加工。例如:加工镍基高温合金(GH4169)的材料去除率可达11 300 mm3/min,而电极损耗率(TWR)低于3%。由此可见,高速电弧放电加工在难切削材料的高效去除加工方面具有明显的技术优势。     

Ultraprecision micromachining of hard material with tool wear suppression by using diamond tool with special chamfer

This study aims to develop an ultraprecision machining method which enables to suppress tool wear in the machining of hard material by using the tool with special chamfer. As a result, the cutting point swivel machining is proposed, and its effect is experimented in the machining of SiC. Then, the relationship between the speed ratio and tool wear is investigated. By applying the proposed machining method to curved microgrooving and curved surface machining on Tungsten Carbide, it is confirmed that cutting point swivel machining enables to realize ultraprecision machining of complex shape.     

工艺参数对电火花电弧高效复合加工性能的影响研究

电火花电弧复合加工解决了电火花加工效率低的问题,与电火花加工相比,其加工效率提高了数倍,针对某些材料,其加工效率甚至超过了传统机械加工,但也存在自动化程度低、电极损耗严重等缺陷。利用电火花电弧复合加工技术进行了大量实验,并以此为基础,分析了不同加工参数下的工件性能,得到在不同峰值电流、脉宽、电极主轴转速等参数下的工件加工效率、表面粗糙度及相对电极损耗率的变化规律,以期得出针对不同加工目的的最优工作参数。     

微细电火花伺服扫描加工实验研究

进行微细电火花三维扫描加工时,由于电极损耗相对严重,导致形位公差难以保证和加工效率较低。该研究分析了电火花加工常规的电极损耗补偿方法,提出了基于放电间隙伺服控制进行电极损耗实时补偿的微细电火花三维扫描加工方法。辅助以电极电接触感知工件平面和加工原点,三维结构加工实验显示,采用间隙伺服控制进行电极损耗实时补偿有利于提高扫描加工微三维结构的形位精度和加工效率。     

Machining Characteristics of EDM by Radio-frequency Plasma

An extension to the electrical discharge machining method by introduction of radio-frequency plasma is proposed. Sparking with the radio-frequency plasma can be generated in paraffin oil by simple electrical circuitry. In this paper, experimental investigations are described on the fundamental effects of the resonant frequency, type of electrode and workpiece materials on machining characteristics for high performance radio-frequency machining in paraffin oil. The results show that the removal rate and the electrode wear vary with the resonant frequency and type of electrode materials. The surface roughness can be reduced to less than 1μm Rz under suitable experimental conditions.     

EDM turning using a strip electrode

Turning by electrical discharge machining (EDM turning) is an effective method to machine hard-to-cut materials. Generally, a wire-EDM is utilized in EDM turning because it is not concerned with electrode wear. However, wire-EDM turning has a slow machining speed due to its small machining area, and the wire may break due to overheating electrodes. For these reasons, its machining speed must be limited. In this study, a strip-EDM was created in an effort to overcome the problems in the EDM-turning process. This machining method used a conductive strip as an electrode. The strip was fed continuously, like a wire-EDM; therefore electrode wear was not a concern. One advantage of the strip-EDM was that it increased the material removal rate because of its large machining area and non-breaking electrode. In the experiments, machining characteristics were investigated according to machining conditions, and practical machining was carried out via fabrication of complex shapes on a shaft workpiece.     

Effect of surface roughness of tool electrode materials in ECDM performance

Electrochemical discharge machining (ECDM) is an emerging non-traditional machining process that involves high-temperature melting assisted by accelerated chemical etching. In this study, the tool electrode (200 μm in diameter) is fabricated by wire electrical discharge grinding (WEDG). After the tool electrode is machined, the surface roughness of tool electrode materials (stainless steel, tungsten carbide, and tungsten) is different because of the physical properties. However, the surface roughness affects the wettability on tool electrode, and also changed the coalesce status of gas film in ECDM. Hence, this study explores the wettability and machining characteristics of different tool electrode materials and their impact on gas film formation. Their machining performance and extent of wear under gravity-feed micro-hole drilling are also examined. Experimental results show that the optimal voltage of different tool electrode can shed light on the machining performance. Moreover, wettability of tool electrode is determined by surface roughness of tool material, which in turn affects the coalesce status of gas film, machining stability and micro-hole diameter achieved. In addition, differences in tool material also results in variations in machining speed. Significant tool wear is observed after repeated gravity-feed machining of 50 micro-holes.     

电火花电解复合加工工作液浓度对电极损耗的影响研究

针对电火花电解复合加工的电极损耗问题,以模具钢为加工对象开展了电火花电解复合加工实验。分析了在不同极性和电极材料条件下,工作液浓度对电极相对损耗、电极形状变化规律及加工精度的影响。结果表明:合理控制工作液浓度能降低电极相对损耗及减小电极形状变化。     

Probability of precision micro-machining of insulating Si3N4 ceramics by EDM

Electrical discharge machining (EDM) is used as a precision machining method for the electrically conductive hard materials with a soft electrode material. But recently we succeeded to machine on insulating material by EDM. The technology is named as an assisting electrode method. The EDMed surface is covered with the electrical conductive layer during discharge. The layer holds the electrical conductivity during discharge. For micro-EDM, the wear of tool electrode becomes lager ratio than the normal machining. So the micro-machining is extremely difficult to get the precision sample.

In this paper to obtain a fine and precise ceramics sample, some trials were carried out considering the EDM conditions, tool electrodes material and assisting electrode materials. Insulating Si₃N₄ ceramics were used for workpiece. The machining properties were estimated by the removal rate and tool wear ratio. To confirm the change of micro-machining process, the discharge waveforms were observed. The micro-machining of the Ø0.05 mm hole could be machined with the commercial sinking electrical discharge machine.     

Performance and Surface Integrity of Ti6Al4V After Sinking EDM with Special Graphite Electrodes

Titanium and its alloys have high chemical reactivity with most of the cutting tools. This makes it difficult to work with these alloys using conventional machining processes. Electrical discharge machining (EDM) emerges as an alternative technique to machining these materials. In this work, it is investigated the performance of three special grades of graphite as electrodes when ED-Machining Ti6Al4V samples under three different regimes. The main influences of electrical parameters are discussed for the samples material removal rate, volumetric relative wear and surface roughness. The samples surfaces were evaluated using SEM images, microhardness measurements, and x-ray diffraction. It was found that the best results for samples material removal rate, surface roughness, and volumetric relative wear were obtained for the graphite electrode with 10-μm particle size and negative polarity. For all samples machined by EDM and characterized by x-ray (XRD), it was identified the presence of titanium carbides. For the finish EDM regimes, the recast layer presents an increased amount of titanium carbides compared to semi-finish and rough regimes.     

复杂型面多轴电火花加工的电极损耗补偿

在复杂型面的多轴电火花加工中,电极损耗对加工精度具有影响显著,因此,对电极损耗进行准确补偿非常重要。通过研究得出电极表面损耗与电场强度有关,并建立了电极损耗系数与电场强度之间的关系。在此基础上,提出了考虑电极运动路径的电极损耗补偿方法,并通过加工实验证明了该方法的准确性与有效性。