锻造液压机的现状及其展望

锻件制造业,特别是大型锻件制造业的发展水平已成为衡量一个国家综合国力的重要标志,锻造液压机的迅猛发展与西方国家军备扩张的需要有很大关系.本文详细介绍了发达国家与我国的锻造液压机的发展历程,并对锻造液压机的现状进行了分析.比较了目前发达国家与我国的锻造液压机的特点,指出随着我国航空航天工业的发展,我国锻造液压机进入高速发展时期,并呈现大型、超大型化的趋势,日前国内自由锻造液压机的规模和锻造力均居世界首位.并提出了可靠性和等温模锻、多向模锻工艺是我国的锻造液压机的研究方向.     

自由锻造液压机的发展与展望

回顾了自由锻造液压机的发展历程,详细介绍各发展阶段自由锻造液压机的类型和技术特点.比较液压油和纯水两种压机工作介质的理化特性,分析了纯水自由锻造液压机的技术优势,为自由锻造液压机的发展提供了研究方向.     

工作缸柱塞连接形式对锻造液压机的影响

针对上压式双柱自由锻造液压机的结构特性和工作状态，分析了工作缸与活动梁连接球铰副的工作条件，阐述了横向偏心锻造与纵向偏心锻造的成形过程，分析了偏载工况下柱塞与缸体的接触状态。结合上压式双柱自由锻造液压机工作缸与活动梁的典型连接形式，研究了工作缸柱塞与活动梁连接形式的工作机理，明确了工作缸柱塞与活动梁的不同连接形式对液压机的影响，确定了适合大型上压式双柱自由锻造液压机的结构形式，研究了合理控制液压机偏心锻造的条件，制定了液压机的偏载控制策略，提出了液压机最大允许锻造偏心距的确定思路，为大型上压式双柱自由锻造液压机的结构设计和安全使用提供了理论依据。     

自由锻造液压机的技术现状及设计分析

阐述了自由锻造液压机的发展过程和我国锻造压机的技术现状,对自由锻造液压机的几种结构型式和传动方式进行了比较,说明了锻造油压机的技术特点。     

大型自由锻造液压机车间工艺设计分析

介绍了自由锻造液压机车间工艺流程及工艺布置,提出了锻造跨+炉子跨双跨和锻造跨+炉子跨+锻造跨三跨两种布置方案,并分析了相应优缺点.另外,详细探讨了液压机、工业炉和其他辅助设备间的配套关系,液压机、工业炉与厂房的相互影响关系以及对公用设施的要求等.对大型自由锻造液压机车间的工艺设计具有较高的参考价值.     

中心管胎模锻造工艺研究

通过对8MN快锻液压机上采用胎模锻造中心管锻件的工艺方案的分析,研究了锻造制坯、模具设计的特点和要点,提出了液压机胎模锻造变形力的计算方法,指出锻造难点、可能出现的问题及预防纠正措施,还提出了液压机胎模锻造模具材料的选用方法.     

80MN双柱式预应力结构快速锻造液压机的设计研发

阐述了80MN油泵直接传动、双柱式预应力结构快速锻造液压机技术特点及设计方法,实现了大型自由锻造液压机结构、传动方式和控制技术的创新.工程应用表明,该锻造液压机整机性能指标达到国际先进水平.     

基于ANSYS的80MN等温锻造液压机有限元分析

80MN等温锻造液压机是根据用户专有的工艺需求而设计的专用液压机,属于重型锻造装备。根据技术协议,要求设计出三维模型,然后采用三维软件SolidWorks对80MN等温锻造液压机进行建模,并利用有限元分析软件ANSYS分析优化液压机的机身结构,合理优化了结构布局和材料的利用率,为公称力在60MN～100MN范围间的等温锻造液压机的快速设计提供了参考和借鉴。     

捷克下拉式自由锻造液压机

原文题为“捷克锻造机组的发展”,介绍捷克两种自由锻造液压机(CKV 型正装式锻造液压机和 CKW 型下拉式锻造液压机)的发展概况。这里仅摘要介绍其下拉式锻造液压机的国内外供货情况,该系列压机的基本参数、本体结构、液压传动和电气控制系统的特点,以及对今后发展的看法。     

大型锻造液压机用加热炉的现状与发展

介绍了国内外锻造液压机用加热炉现状及发展 ,同时叙述了与锻造液压机配套的工具操作机的技术发展     

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.     

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.     

20钢渗硼过程中硼化物形核和生长的TEM观察及室温形变的影响SCIEI

本文采用单向减薄制样法在透射电镜下直接观察了20钢渗硼初期硼化物的形核和生长特性及室温形变的影响。X射线及电子探针分析结果表明:渗硼初期试样表层仅有Fe_2B形成;表层硼原子浓度与形变量之间具有单调增长的关系;偏聚于位错胞壁之中的硼原子阻碍了形变组织的恢复和再结晶,加速了硼化物的形核和长大。     

Influence of Fe on Microstructure and Mechanical Properties in Pdoped Ni–Cr–Fe Alloys

The influence of Fe on the microstructure and mechanical properties of P-doped Ni–Cr–Fe alloys has been investigated.Results showed that increasing Fe content refined the dendrite microstructure and enhanced the solubility of P in as-cast alloys. The change of microhardness in different dendrite regions was attributed to the segregation of P atoms in solid solution state, which had strengthening effects. Increasing Fe contents from 15.2 to 60.7 wt% reduced the yield strength and tensile strength but had little influence on the elongation of alloys. The stress rupture life of alloys after heat treatment decreased with the increment of Fe contents, and the failure fracture modes transferred from transgranular to intergranular fracture mode. The change of fracture modes was due to the weakness of grain boundaries caused by the increment of Fe.In addition, the precipitation of M_(23)C_6 was believed to be related to the segregation of P toward grain boundaries, which led to the fluctuation of carbon and chromium atoms near the grain boundaries in alloys with low Fe contents. Consequently, the increment of Fe decreased the strength of matrix and changed the existence of P atoms and the precipitates at grain boundaries.     

Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

Study of colored anodized aluminum with calcon in sulfuric acidic solution using cyclic voltammetry and impedance measurement methods

The effect of coloring condition of Al with Calcon (sodium 2,2'‐dihydroxy‐azonaphthalene‐4‐sulfonate), on the corrosion resistance of Al in 0.1 M sulfuric acid solution was studied, using cyclic voltammetry and measurement of impedance noise methods. The changes in the corrosion resistance of colored aluminum electrodes were evaluated by measuring the magnitude of impedance and cyclic voltammetric responses of anodized and colored electrodes. An irreversible corrosion response was observed at the cyclic voltammogram of the colored aluminum electrode. The current and threshold potential of corrosion responses strongly depends on the applied conditions during anodizing, coloring and sealing stages. In addition, significant changes in impedance at the ac voltammogram and noise level at some ac frequencies were observed, when the electrodes were colored under various conditions. In this regard, the surface of the electrode was studied by Scanning Electron Microscopy (SEM). Comparison of SEM images of the colored and uncolored aluminum specimens showed that the colored surface contained a significant numbers of pits. The results indicated that coloring aluminum with Calcon could reduce corrosion resistance of aluminum and increase roughness of the oxide film.     

Effects of Sub-zero Celsius Treatment and Tempering on the Stability of Retained Austenite in Bearing Steel

In this work, the influence of sub-zero Celsius treatment and tempering on the mechanical and thermal stability of retained austenite in bearing steel were assessed by tensile test and DSC. Compared with traditional quenched and tempered treatment, sub-zero Celsius treatment obviously decreases the volume fraction of retained austenite. Moreover, the mechanical stability of retained austenite was enhanced due to the accumulation of compressive stresses in retained austenite after sub-zero Celsius treatment and tempering. Meanwhile, the morphology of retained austenite changed from film-like to blocky with austenitization temperature increasing, and the mechanical stability of film-like retained austenite is higher than that of blocky one. The DSC results showed that the activation energy of retained austenite decomposition slightly increased through sub-zero Celsius treatment and tempering. This result may probably be ascribed to partitioning of carbon during tempering. However, the temperature at which retained austenite starts to decompose is unchanged.     

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.     

RESEARCH ON THE FORMATION MECHANISM OF INTERNAL CRACK IN THE CONTINUOUS CASTING SLAB

In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the solid-liquid interface, and the nucleation and propagation process of crack were studied. It is shown that the bending deformation of the interface results in the temperature field change in the front edge of solid-liquid interface, and the occurrence of temperature gradient along drawing direction results in the growth of secondary dendrites. The initial crack formed during the middle and final stage of solidification may extend to the surface of the casting slab and become an internal crack. The results of the theoretical analysis are basically in agreement with that of the experiment.     

Control of mechanized surfacing of stamping tools with modulation of conditions

The results of investigations of the effect of the regulated parameters of low-frequency modulation on the characteristics of deposited beads in reconditioning of the working surfaces of dies of stamping tools are presented. The effect of the frequency and duty ratio of the modulated conditions on the mechanical properties of the deposited layer and the structure of its metal is described. Recommendations are issued for the effective application of technology with the controlled modulated conditions in the reconditioning of the working edges of the dies of the stamping tools.