微细电火花加工中的电极在线制作与检测

将反拷块与线电极电火花磨削（ＷＥＤＧ）装置相结合，成功地实现了微细电极的高效、高精度在线制作 。充分利用机床的数控功能和接触感知功能以及标准量块和ＷＥＤＧ装置，在不增加任何测量附件的情况下，实现了微细电极的锥度及尺寸测量。     

微细电极的正交点电接触在线测量及组合制作工艺

为服务于微细电火花加工用微细工具电极在线制作,提出一种正交点电接触标准细棒的微细电极在线测量方法。将电极轴线与标准细棒轴线正交（垂直）布置,通过电极外径与标准细棒外径之间低压电感知的点接触方式,避免或减少标准棒尺寸误差和安装误差的影响。提出采用自穿孔成形伺服反拷法和线电极磨削法组合工艺,并结合在线测量反馈方式,实现了钨材料微细电极较高效率的在线制作,尺寸可控精度可达±1．5μm。     

微细群电极的加工及其封装技术

介绍了微细群电极的应用情况,分别给出了LIGA方法、电火花超声复合反拷加工法和电火花线切割加工法制作群电极的工作原理,并对这些工艺的特点进行了归纳,给出了具有代表性的加工实例,最后介绍了微细群电极的封装技术.     

自成形微细电极制备技术研究

以目前微细电火花加工中微细电极常用的制备技术为基础,提出了自成形微细电极制备技术。通过研究,掌握了自成形微细电极制备技术工艺关键,并与传统制备方法的反拷块法进行了实验对比,获得了较为理想外形尺寸精度、长径比的电极。     

极性效应在微细电火花反拷加工中的应用

研究了极性效应对微细电火花加工的影响,讨论了微细电火花加工中碳黑膜的生成条件及其对微细电极的保护作用.针对微细电火花反拷加工中电极损耗较大的问题,采取了粗精结合的加工策略,提高了工件的加工精度和表面质量.     

电火花微细电极标准球在线检测方法

设计了标准球电极在线测量系统,它由标准球、支杆及待测电极构成。介绍了测量系统的使用方法,并对其测量误差进行了分析。做了块状电极反拷测量试验,结果表明:系统能准确有效地对电火花微细电极进行在线测量,测量值与非接触式三坐标测量机离线测量值的相对误差小于5%,从而实现了电火花加工微细电极简单、快捷的在线测量。     

喷油器流量控制阀板精密复杂微结构微细电火花加工技术

阐述了共轨喷油器流量控制阀板复杂微结构微细电火花加工解决方案,介绍了研制的三头数控微细电火花加工装备,分析了微细电火花铣电极损耗补偿及锥度沟槽、十字槽等加工工艺,总结出保证微细电火花铣削加工质量和效率的工艺规律。     

基于微细电火花加工技术的微冲裁模具在线制备

针对微冲裁异形截面的微小模具难以制备及安装对准的问题,利用微细电火花三维铣削加工技术加工反拷贝电极及凹模,利用所加工的反拷贝电极通过电火花反拷贝加工技术加工凸模,整个工艺过程在线制作,避免了凸凹模具二次装夹产生的位置误差。该工艺分别在线制作凸凹模具,实现了复杂截面形状微型模具制备和在线对准。通过设计试加工实验确定加工参数,并利用该工艺成功制作了一套截面形状复杂的具有微小特征结构的高精度微冲裁模具。     

基于可重构方法设计的多功能微细电加工系统

简要介绍了可重构制造系统的概念和可重构机床的特点。基于可重构机床模块化的设计方法,设计了一套可进行微细电火花加工和微细电解加工的多功能微细电加工系统。在多功能系统中利用在线电解的方法制备微细钨电极,并用此电极进行电火花微细孔加工试验。     

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。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。