车削加工中进给方向毛刺形态研究

毛刺的产生与存在是金属切削加工中长期存在的问题,按照以切削运动和切削刃为基准的毛刺分类体系,在车削实验的基础上对进 形成机理和形态进行了研究,进给方向毛刺是刀具接近进给方向终端时,部分被切金属产生的变形,离开切削路径而未被切削,留在工件终端面上的被切削层金属,进给方向毛刺是各种形式毛刺中最大的一种,其形成时的变形方式有弯曲和滑移,进给方向毛刺有一次毛刺和二次毛刺两种基本形态,一次毛刺有Ⅰ型毛刺;Ⅱ     

车削加工毛刺的形成及其形态转换

金属切削毛刺是切削加工的常见现象,它直接影响到工件的加工精度。研究以车削加工为基础建立了车削加工中进给方向毛刺形成的数学-力学模型,指出：进给方向毛刺的形成是由于塑性弯曲变形和塑性剪切滑移变形而引起的。并就车削加工中形成的进给方向毛刺形态及其转换进行了研究,揭示出一次毛刺和二次毛刺转换的基本规律。     

车削加工中进给方向毛刺影响因素研究

毛刺的产生与存在是金属切削加工中长期存在的问题毛刺的高度影响工件的精度,毛刺的根部厚度影响毛刺的去除通过 Ｈ６２ 黄铜等材料的车削试验,分析多种切削因素对进给方向毛刺尺寸的影响研究表明,塑性好、强度高的材料加工时容易形成大的进给方向毛刺各种切削参数中切削深度对进给方向毛刺尺寸的影响最明显当切削深度 ａｐ 与刀尖圆弧半径ｒε相等或主偏角接近κｒ ＝ ４５°时,毛刺根部厚度出现极大值合理调整材料的力学性能和切削参数可以抑制或减少进给方向毛刺的尺寸     

形成毛刺的力学解释

金属切削过程中切屑必然朝着切削功最小的方向流动。也就是说,沿切削宽度方向的切削阻力不同,从而剪切角φ亦有变化,致使α段、β段的金属产生指向已加工表面或待加工表面的变形。这种变形“越出”刀具的切削范围时即形成毛刺。     

切削运动——刀具切削刃毛刺分类新体系及其应用

本文对金属切削毛刺分类体系的现状进行了系统的概述和分析,指出其存在的主要问题。提出并建立了切削运动——刀具切削刃毛刺分类新体系,将金属切削毛刺分为两侧、进给和切削方向毛刺三大类,清晰地找出了影响毛刺生成及变化的主要因素。在刨削和钻削加工中应用该毛刺分类体系,表明:切削运动——刀具切削刃毛刺分类体系术语明确、系统完整、简便易行。     

关于切削加工中进给方向毛刺生成机理的研究

本文对切削加工中进给方向毛刺的生成机理进行了实验研究和相应的理论分析,搞清了进给方向毛刺的生成过程、生成机理及其影响因素.进而提出了抑制进给方向毛刺产生的若干措施.它对有效地控制和减少进给方向毛刺的产生、保证和提高切削加工质量、开发抑制切削加工毛刺产生的新方法等具有重要的理论意义和广泛的实用价值.     

金属切削毛刺的形成及预报的研究

金属切削毛刺的形成过程是一个非常复杂的材料变形过程 ,毛刺的形成直接影响着精密零件的棱边质量 有必要对毛刺的预报及控制进行深入、系统的研究 影响毛刺形成的因素众多 ,建立三维切削毛刺形成的模型是非常困难的 本文论述了建立二维直角自由切削中两侧方向毛刺形成的数学—力学模型的方法、毛刺控制图表及毛刺专家系统的研究进展和应用 ,提出了毛刺分类标准研究的必要性     

高速车削碳钢工件表面的微观形貌和结构特征

根据对中碳钢所进行的高速车削实验的观察，对高速车削工件表面微观形貌和表层微观结构的形成过程及其特征进行了分析研究．结果表明，切削速度和材料硬度是决定切削过程中材料变形的主要因素，切削热使被切削材料产生高温软化，形成特有的工件表面犁垄和熔融金属涂抹现象，工件表层材料因切削高温出现二次淬火及回火现象，显微硬度发生改变，并出现了硬脆的白层组织．切削过程中的刀一工相对运动和切削热现象对已加工表面的形成起着至关重要的作用，随着切削用量增大，切削热和摩擦热增大，形成了高速车削工件表面特有的微观形貌和表层微观结构．     

超声微铣削加工毛刺成形特性研究

为减少微细切削加工过程中产生的微型毛刺对微型零件成形加工质量的影响,利用双直槽结构矩形六面体超声变幅器对工件施加水平辅助超声振动,在304奥氏体不锈钢板表面进行微沟槽结构超声微铣削成形加工试验,研究不同超声微铣削参数条件下铣削顶部毛刺的成形特性.试验结果表明,工件的水平超声振动使得不锈钢微沟槽顶部毛刺形态由长条形的絮状结构变为连续的片状结构;且随着超声振幅的增大,片状毛刺的高度逐渐减小,呈微细碎片化趋势.工件的水平超声振动还有利于减小微铣削沟槽顶部毛刺的长度,且当每齿进给量略大于刀具最小切削厚度时,毛刺长度的减小最为明显.      

控制进给方向毛刺的实验研究

本文在对切削加工中进给方向毛剌生成机理研究的基础上,通过实验观察和分析,给出了表示切削加工中进给方向毛刺产生与否的物理量——临界主偏角 x_c,并讨论了若干因素对临界主偏角 x 的影响.进而开发出几种控制和减小进给方向毛剌的新方法.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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