浮动锻造成形技术的发展现状及展望

介绍了浮动锻造加工技术的国内外发展概况与技术展望，阐述了大力发展浮动锻造加工技术的可能性与必要性。     

Research of quasi-solid fracture behavior of casting Al-4.5Cu alloys

The influencing mechanisms of elements Ti and Ce and their interactions on fracture behaviors of casting alloys Al-4.5Cu-0.6Mn were studied by observing tensile fracture behavior in quasi-solid zone under SEM and EDX instruments.The results indicate that the resistance stress against hot cracking can be improved obviously by addition of Ti, because of its grain refining function. It is also found that, when Ce is added into the alloys, besides its effect in refining crystalline, the mechanical behavior of lower melting point eutectic phase in quasi-solid zone can be improved efficiently by some compounds with Ce formed and deposited between dendrites. Therefore, a coiligating effect of Ti and Ce on improving resistance stress against hot cracking is more efficient than that only single alloy element is applied. When hot cracking occurs, grains yield at first, and then crack spreads. Both inter-grain and trans-grain fractures are observed, but the major fracture manner is brittleness.     

Thermoelectric properties of mechanically alloyed iron disilicides consolidated by various processes

Mn doped p-type iron disilicide powders have been produced by a mechanical alloying process. As-milled powders were of metastable state and mostly transformed to β-FeSi₂ phase by subsequent isothermal annealing. As-milled powders were consolidated by various processes such as sintering of the cold compact in vacuum, vacuum hot pressing (VHP), and spray drying/atmospheric plasma thermal spraying. Phase transitions during the processes were investigated using XRD, EDS, and SEM. As-consolidated specimens consisted of a mixture of α-Fe₂Si₅ and ε-FeSi phases, which were gradually transformed into a thermoelectric semiconducting α-FeSi₂ phase by subsequent isothermal annealing in the vicinity of 845°C in vacuum. However, some residual α and ε phases remained even after prolonged annealing. Thermoelectric properties were measured as a function of temperature and correlated with phase transformation. They showed optimum values in the vacuum hot pressed specimen due to a higher fraction of β phase and/or higher density.     

高精度直齿圆柱齿轮冷锻成形加工方法的研究

针对真齿圆柱齿轮冷成形难度大的问题,提出了闭式镦挤－－约束孔分流两步成形实用化工艺方案和基于变位理论的齿形凹模修正设计方法,并对１５、４５、２０ＣｒＭｎＴｉ钢质直齿圆柱齿轮冷精锻工艺进行了系统研究。研究结果表明,两步成形法是降低直齿圆柱齿轮冷精锻成形力的有效方法,提出的齿形凹模修正设计方法可获得较高的齿形精度。     

双孔内六角压块闭式挤锻工艺及模具设计

叙述了双孔内六角压块工艺分析及其锻件图制订 ,介绍了闭式挤锻工艺、模具结构及其基本要求。结果表明 ,闭式挤锻工艺的新方法是十分有效的。     

摆辗技术在火车轮制造中的应用

分析了传统的火车轮锻轧生产中存在的主要问题 ,对摆辗在火车轮制造中的应用进行了研究和探讨。采用摆辗能生产出高质量的火车轮。     

基于三维实体造型的长轴类锻件锻模CAD系统的研制

介绍了以通用的AutoCAD为支撑软件 ,采用三维实体造型技术 ,在微机上实现长轴类锻件锻模CAD系统的全过程。其中包括锻件三维实体造型、计算毛坯图绘制、制坯工步选择、型槽设计、型槽布置和模块尺寸确定、锻模三维实体造型和二维总装图生成。该系统软硬件要求低 ,通用性强。     

基于音圈电机X-Y精密定位平台的控制系统设计

针对由音圈电机驱动的X-Y精密定位平台系统,提出了一种基于S函数的实时离散傅里叶变换(DFT)算法来进行系统辨识,从而建立定位平台的数学模型.基于系统数学模型,采用混合灵敏度优化的方法,设计了一种H∞鲁棒控制器.该控制器对模型的不确定性及外部干扰具有较好的抑制作用,从而能够很好地改善系统性能,并利用仿真及实时控制实验验证该控制算法的有效性.结果表明该控制器较好的改善了系统的动态特性,使其具有响应速度快、稳定性好以及良好的抗干扰能力等优点.     

防火塑料的热流道注射成型

为了弥补目前防火塑料的市场热流道成型的空白,分析了防火塑料注塑的特点,针对防火塑料注射难点进行分析,并针对热流道结构特点深入剖析,提出防火塑料专用热流道注射成型的方案,满足客户对高防火塑料的注塑要求.     

5CrNiMo动叶锻模的热处理

动叶锻模是在高温下通过冲击加压强迫炽热的坯料成为模锻动叶的工具.随着汽轮机制造技术不断发展,动叶型线发生了变化.锻模型腔深度增加,型腔与锻模平面部分区域的变化角度变陡,导致近段时间锻模在动叶模锻时发生了较严重的变形,严重影响锻模使用寿命.经分析,产生上述问题的原因是模具金相组织中存在大量的残余奥氏体.为此,专门对5CrNiMo材料的热处理工艺进行了分析.通过制定合适的工艺,成功解决了残余奥氏体的问题,延长了模具的使用寿命.