基于图形逆向设计的产品线切割加工

为了提高对复杂轮廓图形线切割加工的轮廓精度和表面质量,提出了采用图形逆向设计法获得矢量化轮廓图形,然后采用图形交互式线切割编程加工出零件的方法,并应用此方法试验加工了对称偏置槽槽轮机构中的槽轮与柱销,提高了线切割零件的轮廓精度,保证了零件的表面质量。     

微小型零件的微细切削加工工艺研究

文章研究了微小型零件的微细切削加工工艺,微细切削加工微小型零件具有较大的工艺和成本优势,适应微小型零件产品批量化、加工柔性化、材料多样化的发展趋势.微小型零件按照加工工艺特征大致可分为微小型轴类、三维结构件、板类和齿轮类零件,总结和分析了上述零件的工艺特征和加工方式,介绍了微小型加工机床和刀具的选用原则,包括如何合理选择微细切削刀具的材料、特征尺寸和结构.微小型零件必须根据机床功能和零件自身结构特点确定装夹方式,并进行准确定位.最后,归纳和总结了微小型零件进行微细切削数控加工工艺设计时应遵循的原则,并进行了详细论述.微细切削加工中,采用合理的数控加工工艺和走刀路线,可以实现微小型零件的精确、高效加工,适应批量化的产品需求.     

交互式轴类零件数控加工区域的设计和加工方式的确定

提出了一种轴类零件数控加工区域的设计方法.通过人机交互采用基于零件特征和添加辅助曲线两种方式实现对加工区域的设计,重点实现了辅助曲线的添加、选择以及编辑功能.通过典型工艺路线模块化和参数化辅助用户确定加工方式.所提出的方法克服了UG等CAM软件在轴类零件数控加工中人机交互多、对工程技术人员要求高等缺点,可直接应用于轴类零件数控编程系统的CAPP中,具有较高的实用价值.     

基于机器视觉的轴类零件几何尺寸测量

基于轴类零件的几何特征与CCD获取的零件图像,利用数字图像处理技术对轴类零件进行边缘检测,提出了一种自适应开关中值滤波算法,该方法滤除噪声效果明显,开发了轴类零件尺寸测量系统,实现了轴的尺寸及其参数的测量.实验结果表明,改进的滤波器可以较好的保存图像的二维边缘信息,且在允许误差范围内采用机器视觉的非接触测量方法可以实现对轴的基本参数的快速准确测量.     

基于CAXA软件线切割矢量图的加工研究

随着模具行业的发展,线切割对复杂图形的加工需求越来越多,要想得到理想图形轮廓,常规的CAD系统建模越来越难,本文介绍通过CAXA线切割软件对复杂图象进行矢量化处理方法,最终得到图象的加工轮廓,利用CAXA线切割软件对图象矢量化处理后生成程序代码,然后通过线切割机床完成矢量图的加工,从而提高零件设计和加工效率。     

中小批量横梁小件的数控柔性化工艺应用

通过对商用车车架横梁类和支架类零件结构分析,对比分析了模具加工和手工冷作加工工艺的优缺点.探索了这类零件的最新加工工艺,提出了数控柔性化加工.为中小批量的横梁小件的加工方法提供了新的思路.     

齿轮类零件滚磨光整加工技术现状及发展思考

齿轮类零件是制约我国各类高端装备自主研发的核心基础件,齿轮表面质量对其长寿命、低噪声、高稳定性运行至关重要.在全面分析齿轮类零件多种不同光整加工工艺基础上,从形性协同、一体化普适高效加工的角度,明确了滚磨光整加工工艺改善齿轮类零件表面完整性的优势.在综合概述滚磨光整加工基本特征后,全面系统地综述了国内外有关齿轮类零件滚磨光整加工技术的研究与应用现状,归纳总结了不同工艺的技术原理、特点及适用范围.针对齿轮类零件滚磨光整加工现阶段存在的不同问题,立足优质高效、绿色普适和产业化实用的高质量发展理念,从齿轮结构特征、滚磨光整方式、加工表面演化、复合加工机理、介质基本特征和改性工艺组合等方面,提出了系统的新思考、新策略,对进一步推进齿轮类零件滚磨光整加工技术不断升级发展有积极的参考与借鉴.     

多特征轴类零件加工的刀具补偿技术研究

针对多特征轴类零件加工中的刀具补偿问题,采用局部补偿方式,避免刀具补偿时零件的连接特征加工精度相互影响。以实例分析该方法在FANUC-0iT数控系统中的应用,结果表明:加工多特征轴类零件时,连接特征的加工精度得到了保证,零件整体加工精度得到了提高。     

电火花线切割二维仿形加工的图像处理方法

针对线切割仿形加工的二维图像处理方法进行了研究，给出了一种图像细化和矢量化的具体算法，此方法还可以用于其他二维仿形加工。     

基于UG家电产品外壳型腔电极设计与数控加工

为提高型腔模具电极设计与数控加工的效率和质量,提出了一种快捷的、优化的设计方法.以型腔模具高效率、高质量电极设计与数控加工为目标,结合企业生产实际,采用UG电极设计模块与建模模块相结合的快捷方法进行电极设计,采用优化的数控加工工艺对零件进行数控加工编程,并采用自定义的后处理文件生成了相应数控系统的数控代码.实验结果表明该零件的加工质量达到了预期的加工要求,为型腔模具的电极设计与数控加工提供了设计思路和方法,对其他类零件的数控加工方案具有重要的指导意义.     

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。