模具用Zn-Al-Cu合金老化问题的研究

针对目前国内使用的锌合金模具材料存在老化的问题,本文研究了不同稀土含量对锌合金(ZnAl14Cu10)老化的影响,结果表明,稀土含量(wt%)为0.1%时,为模具用耐老化锌合金的最佳稀土含量。     

粉末热锻模具磨损特性的实验研究与机理分析

为研究粉末热锻模具的磨损特性和磨损机理,文章通过制取预锻坯、设计和制造模具,搭建实验平台,在不同压下量(15.8%、18.1%、20.9%)下进行粉末热锻实验,将经混粉、压制和烧结后的预锻坯锻造到不同的相对密度(92%、94%、96%);对试验前、后的模具沿轴向标记点进行磨损量检测,使用扫描面电镜和物相分析等手段对试验后的模具进行微观分析。试验结果表明:粉末热锻过程中模具的磨损量随着锻造密度的增加而增大;模具在工作段沿轴向上越靠近上端,磨损量越大;粉末热锻模具的磨损机理是氧化和剥落交替进行的动态平衡过程。     

5CrMnMo热锻模具钢的断裂试验研究

为了提高5CrMnMo热锻模具的使用寿命,对5CrMnMo钢在不同热处理条件下的断裂韧性(δ_m)和予裂纹高温系列冲击韧性进行了试验研究,测定了脆性转变温度,提出了合理的淬火回火温度和模具使用前的预热温度.     

我院和大冶钢厂联合研制出高韧性易切削塑料模具钢

9月12日,我院金属材料教研室和大冶钢厂联合研制的高韧性易切削塑料模具钢(5NiSCa)通过国家鉴定。专家们认为:新钢种填补了我国复合系易切削塑料模具钢的空白,在国际上属独创,达到世界先进水平。 这种新钢种,已在全国三十多家厂矿企业的生产中试用,用于注塑模、胶木模、橡胶模、印刷线路板凹板及精密冷冲模等。生产试用表明,新钢种可锻性好,热处理简单,预硬后制模直接使用,提高了模具精度和光洁度,从而提高了塑料制品的表面质量,保证了制品精度,缩短了制模周期,减少了修模次数,提高了模具寿命,降低了成本,能代替进口模具。     

泡沫铜冷却通道对铸造模具冷却的影响

为了在冷却通道内插入泡沫铜强化冷却高温铸造模具,建立了模拟高温铸造模具冷却的实验系统,研究了不同流量下泡沫铜通道和空通道的模具冷却情况。结果表明,当冷却水体积流量分别为0.1、0.2、0.3和0.4m3/h时,使用泡沫铜通道冷却80s后,模具同一位置的温度比空通道冷却分别低16.2、19.3、23.5和29.4℃,冷却排出热流量较空通道分别高414、581、659和660 W;随着流量增加,使用泡沫铜通道的模具同一位置温度降低、局部温度梯度和热流密度增大,说明冷却通道内插入泡沫铜能够实现铸造模具的快速冷却,并可望用于顺序凝固温度控制。     

高强韧性65Cr4W3Mo2VNb基体钢

本文是关于高强韧性65Cr4W3Mo2VNb基体钢的研究报告。文中总结了新钢种多年试验的成果,并着重分析其合金成分,基本性能和热处理工艺。 新钢种在高速钢的淬火基体成分上适当地提高了碳量,同时加入0.2～0.3％的Nb(铌)。实践证明:新钢种冶金质量优良,工艺性能良好,强韧性能高;并可通过热处理工艺的调整,得到强度、韧性和耐磨性能的不同配合,适应多种工作模具的需要;用于制作冷镦、冷挤模具,使用寿命比W18Cr4V,Cr12MoV等钢模具有成倍的提高。这是一种成分设计合理,具有特色的新型冷模具钢钢种。     

生产中冲裁模间隙的合理选择

分析了冲裁模间隙对冲裁质量和模具寿命的影响,介绍了本厂在生产中根据不同的材料性能、厚度、使用要求、设备能力选择合理的冲裁模间隙,保证冲裁质量、提高模具寿命的经验。     

简易压板模具的设计与应用

针对现在冲压零件上常见的特殊成型工艺,本文详细介绍了简易压板模具的设计和使用方法。通过简易压板模具的使用,有效降低模具设计和模具制造成本。     

如何高效使用数控转塔冲床模具

模具使用技术和维护水平也是提高加工质量和模具的使用寿命、控制设备运行成本的重要环节,本文主要论述数控转塔冲床模具在使用中经常出现的问题,并针对这些问题提出相应模具保养与维护的技术要点和注意事项,希望能与同行共勉。     

CVD技术在模具上的应用

化学气相沉积(CVD)涂层TiN、Ti(C,N)是提高模具使用寿命的有效途径。本文总结了涂层模具的使用情况,分析了寿命提高的原因。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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