弧齿锥齿轮和准双曲面齿轮刮削新刀盘设计

在弧齿锥齿轮和准双曲面齿轮的刮削加工工艺中，刮削刀盘需要采用大的负前角和大的负刃倾角，已有的“斜角直线造形法”为解决刀具的强度和易崩刃问题，要求刀具的负刃倾角的绝对值要尽可能大，而此时造形误差又有较大的增加，本文提出“斜角圆弧造形法”既保留了斜角切削刮削刀刃强度好和抗冲击性能好的优点，同时又使造形误差大大减小，抗崩刃能力也得到了增强。     

硬齿面刮削铣刀盘切削应力应变有限元分析

利用大型通用有限元分析软件ANSYS，对弧齿锥齿轮和准双曲面齿轮硬齿面刮削铣刀盘切削进行了应力应变的有限元分析，通过铣刀盘在各种改变参数条件下的应力分布图和变形图，预知刀盘切削时的应力应变大小及分布形式，优化出刀具切削时受力状况良好的刀具几何参数，进—步了解刀具几何参数对刀具强度、刚度等的影响规律，从刀具力学的角度找出刮削刀头易崩刃破损的结构因素。     

弧齿锥齿轮硬齿面刮削过程的几何仿真

根据斜角直线齿形造形方法设计出的弧齿锥齿轮刮削刀盘产形面已不再是一个圆锥面,而是一个双曲面。这个变化对软齿面加工后的接触区产生影响,为了搞清这个影响,根据齿轮局部共轭原理进行了弧齿锥齿轮刮削和啮合的仿真分析。仿真结果表明,刀盘进行刮削后,接触区的走向稍有变化;不同的机床调整参数对接触区影响程度不同;刮削带来的接触区的变化是可以修正的。对刮削时机床调整参数的几何仿真与修正可以达到减少实际加工时的试切次数,提高刮削质量的目的。     

拓扑修形斜齿轮齿面插齿修正

为了提高插齿刀精度和寿命并实现拓扑修形齿轮的加工,提出锥面砂轮轴向冲程点接触刃磨插齿刀及拓扑修形斜齿轮齿面插齿修正方法.首先根据啮合原理和磨削过程中砂轮和刀具之间的运动关系,建立插齿刀切削刃方程;然后通过修正砂轮齿形角、轴向廓形及展成运动,使重磨深度内切削刃误差最小.此外为提高刃磨效率,通过等粗糙度磨齿法,确定砂轮每次冲程的齿面径向位置及冲程总次数.根据切削刃方程,建立2自由度插齿模型;结合插齿齿面误差和给定的目标法向修形面,推导工件的实际插齿目标拓扑修形面,建立基于插齿刀刃形修正参数(砂轮压力角、轴向廓形及展成运动)和插齿运动修正参数(工件转角及插齿中心距)的齿面误差敏感性分析修正模型.通过优化算法求解各参数,实现了拓扑修形齿面插齿修正.     

中硬齿面齿轮的刮削工艺

介绍了中硬齿面齿轮的刮削工艺，叙述了用硬质合金滚刀对齿面进行刮削加工的工艺参数选择原则及刮削要点。     

硬齿面刮削滚刀重磨齿形精度分析

为了保持硬齿面刮削滚刀重磨后的齿形精度,关键的问题是如何确定其前刀面重磨时的偏距数值,而根本的问题则是如何选用合适的铲磨工艺参数.本文用数学解析方法,可求得刮削滚刀前刀面上的侧刃方程、铲磨滚刀的砂轮廓形以及滚刀侧后刀面上各点的三维坐标,从而能得到按一定偏距数值重磨前刀面时侧刃上各点相对于滚刀基本蜗杆螺纹的位置偏差.那么用优选方法就可计算出在容许的偏差范围内各个铲磨工艺参数的数值。     

基于刀具齿廓修形的弧齿锥齿轮齿面设计

为避免表面研磨弧齿锥齿轮在重载情况下发生边缘接触,改善齿面应力分布,用弧线刃刀具替换展成齿轮齿面的直线刃刀具.首先,基于刀具的几何结构建立新型刀具的数学模型,并建立了切削刃锥面;然后,基于非齐次坐标变换建立弧齿锥齿轮在数控机床上的加工方法并获得理想齿面;最后,以face-milled弧齿锥齿轮工作面为例,对基于直线刃刀具和新型弧线刃刀具加工所得的齿轮副进行几何齿接触分析(TCA)和有限元分析(FEA).研究结果表明,提出的刀具齿廓修形方法能够明显改善face-milled弧齿锥齿轮的啮合性能.     

内齿轮刮齿刀修形设计及优化

为了降低内齿轮刮齿的原理性误差,提出了一种刮齿刀修形设计新方法。从具有齿廓修形的齿条刀出发,结合变位渐开线斜齿轮的展成原理,推导了连续变位刮齿刀的齿面方程;联立刮齿刀齿面和前刀面方程,求解刮齿刀切削刃的数学表达式,根据双自由度包络理论和齐次坐标变换,建立内齿轮的刮齿模型,获得内齿轮齿面方程。算例表明,刮齿刀的变位方式、前角和螺旋角是造成原理性误差的主要影响因素;相比于公式法,基于修形齿条刀法的切削刃更接近于反向包络法的切削刃;建立以齿面偏差平方和最小为目标函数,通过优化齿条刀的齿廓修形系数,能够将齿面偏差最大值从18μm降低到3μm,有效地减小原理性误差。此研究可为刮齿刀设计提供一种更简单、精度更高的新方法。     

直齿剐齿刀结构设计与计算

针对剐齿发展的迫切需求,提出一种直齿剐齿刀结构及其参数计算的方法.首先简述了剐齿原理,进而提出直齿剐齿刀前、后刀面的结构形式.在明确刀具结构形式基础上,给出刀具参数及计算方法,并且推导出刀具的齿形误差.采用上述方法设计制造刀具,利用自行设计制造的数控剐齿机床进行实际加工,经Gleason Metrology Systems检测,工件齿形精度达7级,表明上述刀具设计方法有效、可行.     

浅析硬齿面刮削加工技术

介绍采用刮削滚刀滚硬齿面齿轮的技术,指出了硬齿面刮削工艺的特点及对滚齿机的要求,提出了防止崩刃及齿形精度的保证措施,为硬齿面齿轮的经济、高效生产提供了一条新路。     

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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