冲裁模的失效分析与对策

针对冲裁模的主要失效形式，分析了影响冲裁模失效的因素，提出了提高冲裁模使用寿命的措施。采用这些措施，可较大地提高冲裁件的加工质量和生产效率，取得较好的经济效益。     

盲孔钉坯正反挤工艺及模具设计

将落料—挤压—盲孔正反挤压三种工序复合在一套模具上。工件排样采用交叉三排。而且模具结构并不复杂,成功地在40 t冲床上实施了该工艺,使盲孔铝坯件挤压工艺生产率大幅度提高,达到150件/m in。该设计还在落料工序中采用无搭边新技术,一改冲裁落料中有搭边的常规模式,减少了搭边损耗,大大提高了铝板材的利用率。     

盲孔钉坯正反挤工艺及模具设计

将落料-挤压-盲孔正反挤压三种工序复合在一套模具上.工件排样采用交叉三排.而且模具结构并不复杂,成功地在40t冲床上实施了该工艺,使盲孔铝坯件挤压工艺生产率大幅度提高,达到150件/min.该设计还在落料工序中采用无搭边新技术,一改冲裁落料中有搭边的常规模式,减少了搭边损耗,大大提高了铝板材的利用率.     

冲裁间隙对冲裁件质量的影响及其选择方法

冲裁间隙Z是指凹模刃口横向尺寸与凸模刃口横向尺寸的差值，一般用Z表示双面间隙，用Z／2表示单面间隙，如果没有特殊的说明，冲裁间隙就是指双面间隙。冲裁间隙值可以是正值，也可以是负值，但在普通的冲裁中，均为正值。     

浅析设计因素对冲模寿命的影响

分析了冲裁间隙、模具结构型式、制件毛坯、冲压设备等设计因素对冲裁模具寿命的影响方式和程度,提出了模具设计时根据冲裁件形状、尺寸、精度、材质和制件批量等方面的要求选择冲裁间隙、模具结构型式的基本原则和方法。     

B1500 HS硼钢热冲裁过程的相变和冲裁精度

为了研究热冲裁零件微观组织及尺寸精度的变化规律,采用不同的冲裁温度和模具间隙比对B1500HS钢板进行了热冲裁试验.根据冷却曲线,研究了冲裁温度对硼钢组织转变和零件力学性能的影响;根据落料件的尺寸,分析了冲裁温度和模具间隙比对尺寸精度的影响;通过观察零件的断口形貌,分析了冲裁温度对断口质量的影响.结果表明:当冲裁温度一定时,落料件的尺寸随着模具间隙比的减小而增大;当模具间隙比一定时,落料件的尺寸误差随着冲裁温度的降低出现"正—负—正"的增长波动趋势;当冲裁温度为600~650℃或750~800℃时,落料件具有较高的冲裁精度;落料件的硬度随着冲裁温度的升高而增大,当冲裁温度为650~800℃时,落料件的组织为马氏体,硬度值HV约为550;冲裁断面光亮带的宽度随着冲裁温度升高而增大.     

中厚板冲裁问题研究

分析了中厚板冲裁时影响冲裁力的几个主要因素,并由实验确定了对于给定厚度的板料,斜刃口模具倾角α对冲裁力的影响是主要的,凸、凹模间隙次之。在模具结构设计方面,斜刃口模具可采用快速换模结构,以提高生产率。     

基于AUTOCAD的板材优化排样问题的研究

分析了在有限长、宽的整体板料上对单一冲裁件优化排样的方法、步骤及其关键技术，重点讲述了冲裁件排样单元的构造和冲裁步距的求解，指出了冲裁件优化排样设计的特点。     

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。     

闭式压力机冲裁过程中的振动分析

本文对闭式压力机冲裁时的振动问题进行了探讨。文中以Ｊ３６－８００Ｂ压力机为例，建立了五自由度力学模型，自编程序进行理论计算，理论计算值与实验测试值吻合较好。所建立的五自由度力学模型优于以往的二自由度力学模型，采用的计算方法与计算程序可以模拟压力机及其它锻压设备的冲裁工艺，所获数据可为采取减振、隔振措施提供参考。     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has