干式切削中刀具选用试验

切削液的使用带来了许多负面问题,鉴于环境考虑,研究绿色加工技术将是机械制造业必须重视的课题.干式切削是解决途径之一,它不用切削液,可完全消除切削液带来的一系列负面影响.本文通过选用一些新型刀具,在干式切削条件下对不同的刀具材料、刀具几何参数和切削用量进行试验比较,以寻求适用于干式切削的刀具材料与切削规律.     

干式加工--金属切削加工发展的趋势

干式加工是金属切削加工发展趋势之一。切削液在加工中对降低切削温度起了很好的作用，也有利于断屑和排屑；但同时也存在一些问题，如冷却液的使用、存储、保洁和处理等都十分烦琐，成本高，而且切削液对环境和操作者身体健康有危害。因此，未来加工的方向是采用尽量少的切削液，而耐高温切削材料和涂层使得干式加工变为可能。１干式加工刀具设计干式加工刀具必须具备下列条件：使用高耐热耐磨性的刀具材料；切屑和刀具之间的摩擦系数要尽可能小；刀具形状保证排屑流畅，易于散热；高的强度和冲击韧性。因此，干式刀具设计必须考虑如下３个…     

基于静电冷却系统的干式镗削加工分析

静电冷却干式切削技术具有资源易取、成本低廉、低能环保等优势,在某些切削领域正逐渐代替切削液的使用。以镗削加工为例,设计搭建出静电冷却干式切削加工实验平台。经过一系列的加工对比实验及DEFORM有限元工艺分析,得到镗削加工过程中切削力、切削温度、刀具磨损等相关数据。结果表明:在镗削过程中与纯干式切削相比采用静电冷却技术可显著降低切削力及切削温度,提高刀具使用寿命,并且基本达到了湿式镗削加工的标准;在镗削加工中采用静电冷却干式切削的新型工艺可以替代切削液的使用而投入到实际加工生产中。     

高速干切削技术分析

面向环境的绿色工艺设计是实现绿色制造的有效途径，是制造业可持续性发展的重要方向，保证企业的经济效益和社会效益最优化。在切削加工中大量使用切削液进行冷却润滑提高了加工成本并带来环境污染问题，消除这些与使用切削液有关的问题的合理措施是采用高速干切削方式。文章提出了干切削技术的新内涵，分析了高速干切削技术的绿色特征，重点分析了实现高速干切削的机床技术，刀具技术和工艺技术。     

准干式切削技术的研究进展

针对传统切削加工过程中使用切削液的弊端,分析了准干式切削技术的特点,介绍了微量润滑、低温微量润滑和水蒸气冷却等常见准干式切削技术的原理及其国内外研究现状,指出准干式切削技术具有很好的节能环保、降低加工成本等优点,具有广泛的应用前景。     

准干式切削技术的研究进展

针对传统切削加工过程中使用切削液的弊端,分析了准干式切削技术的特点,介绍了微量润滑、低温微量润滑和水蒸气冷却等常见准干式切削技术的原理及其国内外研究现状,指出准干式切削技术具有很好的节能环保、降低加工成本等优点,具有广泛的应用前景。     

干切削技术的研究和应用进展

针对传统切削加工过程中使用切削液的弊端,分析了干切削技术的特点,介绍了硬车削技术、静电冷却干切技术和低温冷风干车削技术等常见干式切削技术的原理及其国内外研究现状,指出干式切削技术具有很好的节能环保、降低加工成本等优点,具有广泛的应用前景.     

不锈钢切削加工中刀具切削参数的合理选择

阐述不锈钢的主要切削特点。为解决不锈钢加工困难的问题,从选择刀具材料、刀具角度、切削用量和切削液等方面对不锈钢的切削加工进行分析和研究。     

干式加工——未来金属切削加工发展趋势之一

近年来，特别是工业发达国家非常重视干式切削。为了贯彻环境保护政策，更是大力研究、开发和实施这种新型加工方法。切削液在加工中对降低切削温度起了很好的作用，也有利于断屑和排屑，但同时也存在一些问题，冷却液的使用、存贮、保洁和处理都十分繁琐，且成本高。     

新一代切削刀具AIP涂层SX系列

近10年来,涂层技术在切削刀具上的应用得到了快速普及,涂层刀具已成为切削加工不可缺少的主流刀具。与此同时,随着切削加工向高速切削、强力切削和干式切削的迅速发展,对涂层刀具的性能提出了更高要求。本文就刀具涂层技术的现状、开发动向以及日本JFE精密株式会社开发涂层新技术的情况作一简介。     

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).     

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.     

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.     

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。