钛合金电火花多次切割表面气体强化研究

分析了采用电火花线切割多次切割工艺对钛合金进行表面气体强化处理的可行性,前几次切割采用复合工作液为冷却介质,最后一次采用压缩空气或氮气作为放电介质,对钛合金加工表面进行强化.对比实验表明,以气体作为强化介质时,加工表面硬度得到明显提高,采用氮气进行强化的表面显微硬度达到2 050 HV,是基体的486%,形成了氮化钛组分,且表面基本不存在电解微孔洞和显微裂纹,表面完整性也得到明显改善.     

基于混粉内冲液的微细电火花深小孔加工

电火花深小孔加工常采用管电极内冲液的方式促进电蚀产物排出,以提高加工速度、深小孔的加工质量和深径比。以自来水为工作液开展实验,首先通过正交试验确定深小孔加工的最优参数;然后在工作液中分别混入不同磨料,对比分析不同磨料对深小孔加工效果的影响。结果发现：添加半导体磨料有利于提高加工效率、减小孔的锥度并降低孔壁表面粗糙度值,而添加绝缘体磨料有利于降低电极损耗;混粉浓度和磨料粒径对加工效率、电极损耗、孔径及孔壁表面粗糙度均有明显影响;射流磨料对工件产生磨蚀效果并在孔壁表面留下刮痕,可减少或去除电火花加工表面的重铸层。     

超声振动辅助混粉电解电火花加工工艺研究

提出了一种使用超声振动辅助混粉电解电火花铣削加工硬脆性非导电材料的方法。通过对高硼玻璃进行超声振动作用下的混粉电解电火花铣削加工实验,研究了超声振动对电解电火花铣削加工表面质量的影响规律。结果表明:采用超声振动辅助混粉电解电火花加工,可获得较好的表面质量。     

应用线电极磨削法的电火花微孔加工

在微细电火花微孔加工中，微细工具电极的制作精度是决定微孔加工质量的关键。本文介绍了作者研制的微细电火花加工样机。该机床应用了线电极电火花磨削法制作微细轴，并在同一台机床上用制作的微细轴作为工具电极加工微孔；同时为提高微孔的加工质量，采用了主轴横轴布局结构。该机床还采用了微能放电电源、去离子水工作液等加工工艺。经过实验加工，获得了高质量的微细轴以及微孔。     

超声辅助电火花线切割工艺的研究和探索

研究了电火花线切割加工中线电极高频振动对加工状态的影响,设计了一套超声辅助电火花线切割加工的实验装置,并对复合加工的机理和特性进行了研究和探讨。     

场致射流微细放电加工实验研究

对场致射流微细放电加工单晶硅进行了工艺实验研究,分析在不同加工极性下的加工机理,发现在正极性加工时,蚀坑在工件表面存在电解液残留是由电火花蚀除和电化学蚀除共同作用的结果,而在充分放电的情形下,是由电火花放电来实现材料蚀除的;在负极性加工时,蚀坑仅仅是由电火花蚀除作用的结果。通过单因素实验获取喷管内径、极间距离、极间电压及工作液浓度对单次放电蚀坑直径的影响曲线,通过优化工艺参数在单晶硅表面加工出宽度为1μm、长度为5μm的微细沟槽。研究结果充分证明了场致射流微细放电加工的加工能力。     

应用线电极磨削法的电火花微孔加工

在微细电火花微孔加工中,微细工具电极的制作精度是决定微孔加工质量的关键。本文介绍了作者研制的微细电火花加工样机。该机床应用了线电极电火花磨削法制作微细轴,并在同一台机床上用制作的微细轴作为工具电极加工微孔;同时为提高微孔的加工质量,采用了主轴横轴布局结构。该机床还采用了微能放电电源、去离子水工作液等加工工艺。经过实验加工,获得了高质量的微细轴以及微孔。     

电火花加工放电介质的研究

通过对电火花加工放电通道中等离子体柱的形状和放电通道的电流、电磁特性进行分析,并对电火花加工中不同介质的加工性能进行对比和总结,提出电火花加工介质的技术研究方向应符合绿色制造和资源的可持续发展的理念。     

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。     

气雾介质放电诱导烧蚀成形加工技术研究

利用氧气与水产生雾化工作介质,使金属与间歇通入极间的气雾介质发生烧蚀,以获得较高的材料去除率。在氧气关闭阶段,则通过内冲液对烧蚀表面进行电火花加工修整,去除烧蚀产生的氧化层,在提高蚀除效率的同时,获得较好的表面质量(简称冲液雾化烧蚀)。分析了该加工方法的极间放电状态及微观加工过程,并以Cr12工件进行成形加工实验,与常规水中电火花加工及间歇通氧烧蚀加工进行对比,结果表明:冲液雾化烧蚀加工的材料去除率比间歇通氧烧蚀加工提高近1.45倍,比常规水中电火花加工提高约9.59倍;电极质量相对损耗比间歇通氧烧蚀加工增加约45%,比常规水中电火花加工减少近50%;加工表面比间歇通氧烧蚀加工更光整,表面微观形貌与常规水中电火花加工更接近,且无明显烧蚀重熔颗粒。     

PZT激励同步压缩放电通道微细电火花加工工艺参数对加工结果的影响

提出了压电陶瓷(piezoelectric ceramic transducer,PZT)激励同步压缩放电通道微细电火花加工,目的在于改善微细电火花加工的放电环境。介绍了PZT激励同步压缩放电通道微细电火花加工原理,研究了开路电压、脉冲宽度、脉冲频率和峰值电流对其电极损耗和材料去除率的影响,并与不采用压缩通道方法的微细电火花加工进行了对比。结果表明:同等条件下,采用PZT激励同步压缩放电通道技术,提高了加工过程的稳定性和材料去除率,降低了电极损耗率,有效改善了放电环境。     

Machining performance on hybrid process of abrasive jet machining and electrical discharge machining

To develop a hybrid process of abrasive jet machining (AJM) and electrical discharge machining (EDM),the effects of the hybrid process parameters on machining performance were comprehensively investigated to confirm the benefits of this hybrid process.The appropriate abrasives delivered by high speed gas media were incorporated with an EDM in gas system to construct the hybrid process of AJM and EDM,and then the high speed abrasives could impinge on the machined surface to remove the recast layer caused by EDM process to increase the efficiency of material removal and reduce the surface roughness.In this study,the benefits of the hybrid process were determined as the machining performance of hybrid process was compared with that of the EDM in gas system.The main process parameters were varied to explore their effects on material removal rate,surface roughness and surface integrities.The experimental results show that the hybrid process of AJM and EDM can enhance the machining efficiency and improve the surface quality.Consequently,the developed hybrid process can fit the requirements of modern manufacturing applications.     

超声振动磨削放电复合加工SiCp／Al试验研究

针对SiCp／Al的加工,提出一种超声振动磨削放电复合加工的方法．从加工效率、加工稳定性及表面质量等方面与电火花加工进行了对比试验研究。分析了两种加工方法的脉冲宽度和峰值电流对加工速度和表面粗糙度的影响,结果表明：电火花加工的表面粗糙度平均值为尺04．5μm,超声振动磨削放电复合加工的表面粗糙度平均值为Ra2μm：超声振动磨削放电复合加工的稳定性比电火花加工好,但加工速度较低。通过扫描电镜对两种加工方法下零件表面形貌和重熔层进行了观测,对试件表面进行了X射线衍射分析,表明采用超声振动磨削放电复合加工SiCp／Al复合材料可获得较好的表面质量。     

倒锥形微细喷孔电火花加工研究

高端柴油发动机喷油嘴的微细喷孔要求孔径沿喷射方向逐渐变小形成倒锥形。为实现电火花加工微细倒锥形喷孔,解决倒锥角度高分辨率连续可调、微小锥角顶点的精确定位、无自转微细电极丝推摆动力传递等关键性技术问题,设计研制了一种微细倒锥孔电火花加工用电极丝推摆机构模块,并对该机构模块的推摆径向跳动误差、倒锥角调节误差等性能进行了测试。为验证该机构模块的功能效果,进行了不同倒锥角微细孔加工实验。结果表明:倒锥推摆机构具有倒锥形微细喷孔加工应用的可行性。     

Machining characteristics of magnetic force-assisted EDM

The gap conditions of electrical discharge machining (EDM) would significantly affect the stability of machining progress. Thus, the machining performance would be improved by expelling debris from the machining gap fast and easily. In this investigation, magnetic force was added to a conventional EDM machine to form a novel process of magnetic force-assisted EDM. The beneficial effects of this process were evaluated. The main machining parameters such as peak current and pulse duration were chosen to determine the effects on the machining characteristics in terms of material removal rate (MRR), electrode wear rate (EWR), and surface roughness. The surface integrity was also explored by a scanning electron microscope (SEM) to evaluate the effects of the magnetic force-assisted EDM. As the experimental results suggested that the magnetic force-assisted EDM facilitated the process stability. Moreover, a pertinent EDM process with high efficiency and high quality of machined surface could be accomplished to satisfy modern industrial applications.     

分层厚度对微细电火花铣削加工模具及热压制品表面粗糙度的影响

分层厚度直接影响微细电火花铣削加工的加工效率及表面粗糙度。为了合理规划微细电火花铣削加工的分层厚度,提高加工效率,研究了分层厚度对微细电火花加工的模具型腔及相应热压成形制品表面粗糙度的影响,同时分析了热压成形制品表面与微模具型腔表面之间的关系,以及热压前、后微模具型腔表面轮廓的变化。结果表明:当电极轨迹重叠率一定时,模具型腔底面的表面粗糙度值随着分层厚度的增加而增大;分层厚度对型腔侧壁表面粗糙度无明显影响;热压制品表面轮廓算术平均偏差小于模具型腔表面轮廓算术平均偏差;热压后的模具表面轮廓发生了变化,表面粗糙度值Ra和峰高Rpk减小,峰谷Rvk增大。     

超声电火花复合加工钛合金表面质量研究

采用电火花加工及超声电火花复合加工的方法对TC4钛合金进行了加工实验,分析了小电参数下两种加工方法中脉宽和峰值电流对表面粗糙度的影响,研究表明超声电火花复合加工可有效地降低零件表面粗糙度值.通过扫描电镜对零件表面形貌的分析和重熔层厚度的观测以及零件表面X射线衍射分析,表明采用超声电火花复合加工钛合金零件可获得较好的表面质量.     

Influences of pulsed power condition on the machining properties in micro EDM

Micro EDM is one of the most powerful technologies which are capable of fabricating micro-structure. However, there are many operating parameters that affect the micro EDM process. Since the EDM is basically a thermal process, the supplying electrical condition can be an important factor. The conditions generally consist of several parameters such as electrical current, voltage, pulse duration, spark gap, and others. Those are decisive in removal rate, wear rate, and machining accuracy, which are characteristics of EDM. In this study, the influences of EDM pulse condition on the micro EDM properties were investigated. Voltage, current, and on/off time of the pulse were selected as experimental parameters based on a simple equation for the material removal rate. The pulse condition is particularly focused on the pulse duration and the ratio of off-time to on-time, and the machining properties are reported on tool wear, material removal rate, and machining accuracy. The experimental results show that the voltage and current of the pulse exert strongly to the machining properties and the shorter EDM pulse is more efficient to make a precision part with a higher material removal rate.     

Analysis of the electrochemical behaviors of WC–Co alloy for micro ECM

Micro electrochemical machining (ECM) of tungsten carbide with cobalt binder (WC–Co) was studied using ultrashort pulses. In ECM, the machining characteristics were investigated according to machining conditions such as electrolyte, workpiece potential, and applied voltage pulse. Using a mixture of sulfuric acid and nitric acid, microstructures with a sharp edge and good surface quality were machined on tungsten carbide alloy. The potentials of workpiece electrode and tool electrode were determined by considering the machining rate, machining stability, and surface quality of products. With the negative potential of the workpiece electrode, oxide formation was successfully prevented and shape with good surface quality in the range from R_a 0.069 μm to 0.075 μm were obtained by electrochemical machining. Moreover, the performance of ECM, which includes machining gap, tapering, surface roughness, and machining time, without tool wear was compared with that of electrical discharge machining (EDM). Microstructures of WC–Co with a sharp edge and good surface quality were obtained by electrochemical milling and electrochemical drilling. Micro electrochemical turning was also introduced to fabricate micro shafts.     

Achieving Small Structures in Thin NiTi Sheets for Medical Applications with Water Jet and Micro Machining: A Comparison

NiTi shape memory alloys (SMA) are used for a variety of applications including medical implants and tools as well as actuators, making use of their unique properties. However, due to the hardness and strength, in combination with the high elasticity of the material, the machining of components can be challenging. The most common machining techniques used today are laser cutting and electrical discharge machining (EDM). In this study, we report on the machining of small structures into binary NiTi sheets, applying alternative processing methods being well-established for other metallic materials. Our results indicate that water jet machining and micro milling can be used to machine delicate structures, even in very thin NiTi sheets. Further work is required to optimize the cut quality and the machining speed in order to increase the cost-effectiveness and to make both methods more competitive.