钻轴承钢群钻钻尖几何参数的优化试验

在前人对钻轴承钢群钻几何参数优化的初步试验基础上，做了进一步优化试验，优化出钻轴承钢深孔群钻的外刃顶角和结构圆角后角的较优值分别是１００°和８°左右。     

振动钻削时麻花钻的刀具角度分析

结合低频轴向振动钻削,对麻花钻工作角度的变化规律进行了系统的分析研究,给出了各切削刃工作角度的理论计算公式,结果表明,振动参数取：a=(1~2)s,f/n=2.125~2.25时,可使麻花钻各切削刃在工作前角较大的情况下进行切,在工作前角较小的情况下空切,从而使排屑顺利,主切削刃后面磨损趋于均匀,与普通钻削相比,耐用度提高2倍以上。     

枪钻几何结构参数对钻削力影响规律的研究

枪钻钻头自身独特的复杂结构使深孔钻削的过程变得较为复杂。钻头几何结构参数设计的不合理会引起钻削力较大,导致温度升高、刀具磨损严重和降低孔加工质量等一系列问题。本文通过对钻头静力学分析,借助群钻钻削力的计算方法,将刀具内、外刃分解为微切削单元进行分析进而建立枪钻钻头的力学模型。通过数值仿真研究枪钻钻头几何结构参数的改变对钻削力变化的影响规律,从而进一步优化相关参数并通过实验验证。试验结果表明,钻削力的变化与仿真分析的规律相吻合,进而为枪钻几何结构的优化设计提供了依据。     

双曲面麻花钻几何参数与刃磨参数关系探讨

探讨了目前还没有引起研究人员广泛关注的双曲面麻花钻的几何参数和磨削成型这种钻型所必须的一组刃磨参数。由于该钻型的主刃是双曲面上的曲线，主刃上任一点的锋角都不同，无法代表整个主刃的结构特点。因此用主刃的外缘和横刃转点的锋角作为其设计几何参数值，并以尾隙角为补充参数，建立确定双曲面刃磨参数的一组方程。     

非共轴螺旋面微孔钻钻尖的数学模型

根据深微孔加工的特点,阐述了研究钻削深微孔用新型钻尖的重要性;建立了新型钻尖后刀面和前刀面的数学模型;介绍了主切削刃的求解以及非共辆螺旋面钻尖刀面的刃磨原理;得到了给定刃磨参数下钻尖的计算机仿真的结果。     

群钻钻削力试验及其分析

通过试验得出了群钻切削刃段钻削力的分布规律和切削用量对钻削的影响。     

双圆弧谐波传动刚轮插齿刀设计与齿形误差分析

双圆弧刚轮插齿刀几何参数的计算设计及齿形误差分析是谐波传动制造的难点之一.采用运动学法精确建立双圆弧刚轮插齿刀齿形及齿面数学模型;研究了双圆弧刚轮插齿刀顶刃后角对插齿刀可刃磨长度的影响规律;提出了侧刃后角、侧刃前角等几何参数的计算方法,研究了这些参数的影响因素及从齿顶到齿根的变化规律;分析了顶刃前角、顶刃后角对双圆弧刚轮插齿刀齿形误差的影响规律;通过算例给出了插齿刀前后角的设计方法.结果表明:插齿刀可刃磨长度随顶刃后角增大而减小;侧刃后角的大小与该点半径及压力角大小有关,并随顶刃后角增大而增大;侧刃前角随顶刃前角及顶刃后角增大而增大,其中顶刃前角的影响较大;顶刃前角与顶刃后角均对插齿刀齿形误差有较大影响,设计时应在保证齿形精度的情况下,选择较大的顶刃前角和较小的顶刃后角.     

CNC7轴钻头刃磨机运动控制问题研究

本文讨论了CNC 7轴钻头刃磨机的原理及群钻和普通麻花钻的刃磨过程。以锥面作为钻头后刀面的数学模型,根据钻头的结构参数,计算机求出其对应的一组刃磨参数,并控制刃磨机磨削出理想的钻型。     

枪钻加工的排屑故障及处理对策

枪钻深孔钻削中的排屑问题是目前仍存在的一个技术难题,为防止切屑堵塞,造成钻头折断,降低产品制造成本,分析了排屑故障产生的原因,研究表明及时修磨磨损的切削刃,保持刀具各表面良好的表面质量,保证钻套与工件的良好配合,防止钻削过程中的震动,以及选择良好的深孔零件材质,合理的切削液供油压力及流速,合理改变切削刃的形状和几何参数,可有效保证枪钻在深孔加工中排屑通畅.     

CNC群钻刃磨原理及参数的确定

讨论了ＣＮＣ群钻刃磨机的刃磨原理,以锥面作为钻头刀面的数学模型,根据钻头的结构参数,计算机求出其对应的一组刃磨参数,用于控制刃磨机磨削出理想的钻型。     

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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