附加扭矩优化圆柱体镦粗成形的有限元模拟

镦粗时在模具上增加扭矩能将接触摩擦从被动的阻力变成促进金属流动的动力，这样会降低成形载荷，且使变形均匀。本文利用有限元模拟软件DEFORM-3D，模拟材料A12017的圆柱体在室温下的扭压复合加载成形。分析证明，附加扭矩将优化传统镦粗变形。     

钢中夹杂物在镦粗过程中的运动行为

在镦粗变形中金属的流动行为不仅影响变形抗力的大小，而且会影响变形工艺设计的准确性。目前，在钢的镦粗试验方法中，关于金属夹杂物流动问题的有限元分析法尚不完善，本文提供了由试验得到的金属夹杂物流动行为的资料。试验证明，在镦粗过程中金属的流动并不是有限元解出的变形单元的连续移动。     

圆环在平板间镦粗变形规律的数值模拟

采用有限元模拟软件对圆环在平板间镦粗过程进行了研究,确定了毛坯形状、摩擦因子、变形程度等因素对圆环镦粗成形时金属流动的影响.该数值模拟结果对圆环镦粗时各种因素之间确定了量化的关系,对环形件镦粗提供了科学依据.     

大型曲轴镦锻过程中材料的变形抗力分析

介绍了大型曲轴镦锻成形的特点,建立了坯料和模具的CAD装配模型；应用CAE数值模拟技术对曲轴的镦锻过程做了分析,得到了曲柄成形的位移场、主要模具的应力场和载荷曲线图,得到了材料的最大变形抗力,即最大的镦锻力；最后分析了变形抗力对模具磨损的影响.     

台阶形杆件的冷镦及其模具

在冷镦粗带台阶的杆形紧固件时,由于金属的组织结构、成分不均匀,模腔表面摩擦力和受力状况的影响,往往不能使被镦锻部分按理想状态变形。在多工位自动冷镦机上生产这类工件时,容易产生如图1中A所示的缺陷。一、镦锻过程中的金属流动     

提高自由镦粗成形质量的工艺方法与有限元模拟

讨论各种提高镦粗成形质量的工艺方法,分析扭压复合加载成形过程,并比较这些方法的优缺点。扭压复合加载通过把摩擦力转化成促进金属流动的主动力,将提高金属流动性。运用DEFORM 3D软件模拟了Al2017在室温下的扭压复合加载变形过程,其结果证明此方法有利于减小镦粗鼓形和变形力,提高变形均匀性。     

连续变断面体挤压过程金属的变形特征

采用铅试料，用网格法实验观测连续变断面循环挤压法挤压时金属的流动特征。研究表明，正挤压时，金属在模腔中延伸变形成圆台体，受模具形状影响，变形程度从顶端向底端逐渐减小；圆台体镦粗时金属在高度方向从顶端至底端各层沿径向流动逐渐减小，依次连续变形成圆柱体。这种变形特点使试料在变形过程中逐渐渗透达到累积的效果，并且未出现圆柱体镦粗时的鼓形现象，也未出现因失稳导致的界面叠层。     

粉末盘预制坯两次镦粗成形工艺的有限元模拟与分析

采用商用有限元软件，对FGH96合金盘坯的两次镦粗成形工艺进行了有限元数值模拟。通过对丕同圆弧半径模具镦粗成形过程的模拟，分析研究了模具圆弧半径对预制坯相对直径比以及镦粗后盘坯变形均匀程度的影响规律，同时对镦粗过程中等效应变速率的变化规律进行了分析，得到了合理的模具圆弧半径的取值范围，从而为粉末盘件预制坯的工艺制定提供了一种新的选择。     

芯轴交换对直齿圆柱齿轮精锻成形的影响

为了降低直齿圆柱齿轮精锻成形载荷并防止终锻载荷急剧上升,在分析了圆柱体镦粗接触面上的压力分布规律的基础上,提出了芯轴交换技术,使坯料在镦挤时始终有自由流动的空间,并设计了实验模具和实验方案,通过Deform-3D对芯轴交换的模拟和实验研究,证明了芯轴交换技术在直齿圆柱齿轮精锻成形中对降低成形载荷的有效性.     

基于AFDEX的45°斜三通挤压成形工艺数值模拟及试验研究

基于AFDEX有限元软件,建立了某规格45°斜三通挤压成形热力耦合有限元模型,揭示了成形过程中等效应变、载荷-时间曲线和模具应力的分布规律,得到了挤压该规格45°斜三通件挤压设备吨位.研究结果显示,高应变值主要集中在坯料金属流经垂直冲头的区域;由载荷-时间曲线可知,镦粗开始后,镦粗杆的载荷先缓慢上升,之后快速增大,直到镦粗结束,成形载荷为42410 kN;反挤压开始后,随着加载过程的进行,反挤压杆的载荷迅速增大至约23000 kN,之后一段时间内相对趋于稳定,最终,成形载荷为34920 kN.结合工艺试验,镦粗和穿孔的成形载荷分别为41520和34500 kN,与模拟结果非常接近,验证了工艺方案的合理性,模具结构满足要求.     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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