基于四自由度并联机构的数控机床研究

介绍一种基于混合型四自由度并联平台机构平发的五坐标并联机床,由于其独特的机构设计,与基于Stewart平台的并联机床相比,X方向的进给运动与运动平台分离,改由工作台单独进给,因而其工作空间成倍增大,采用龙门框架结构和滚珠丝杠支承方案使机床获得更高的刚度,给出了该机床运动学逆解,控制系统采用基于PC的数控系统进行五轴三联动控制。     

微细电火花加工机床微进给机构的分析

微进给机构是微细电火花机床最重要的组成部分之一.运用直接耦合的方法,在ANSYS软件环境下,对微细电火花机床的微伺服系统中的高频响微进给机构进行了结构的静态分析和模态分析,得到该压电微进给机构的固有频率和振型以及在电压激励下的最大变形量,并据此设计加工出微进给机构.结果表明,所设计的微进给机构具有很高的固有频率,可以实现高精度、高频响进给,满足了微细电火花加工的要求.采用所设计的微进给机构进行的微细电火花加工获得了非常好的效果,加工效率大大提高,加工质量明显改善.     

微细电火花加工机床微进给机构的分析

微进给机构是微细电火花机床最重要的组成部分之一。运用直接耦合的方法，在ANSYS软件环境下，对微细电火花机床的微伺服系统中的高频响微进给机构进行了结构的静态分析和模态分析，得到该压电微进给机构的固有频率和振型以及在电压激励下的最大变形量，并据此设计加工出微进给机构。结果表明，所设计的微进给机构具有很高的固有频率，可以实现高精度、高频响进给，满足了微细电火花加工的要求。采用所设计的微进给机构进行的微细电火花加工获得了非常好的效果，加工效率大大提高，加工质量明显改善。     

重型机床超长进给机构齿条与减速器的选型计算

在重型机床超长进给机构,一般采取齿轮齿条传动结构来保证进给运动的高精度,体现设计思路的先进性,选择合适的驱动装置将有效的提升机床的性价比。文章以实例的方式详细介绍了进给机构驱动装置——减速器的选型计算,并在应用中作一说明。     

高速数控机床智能进给控制器研究

高速进给系统是高速切削机床的关键技术之一。文章介绍以直线电机为核心组成的高速进给系统,分析了系统的组成结构,建立其数学模型,并设计了新的模糊进给控制系统,比较了新系统与传统进给系统的仿真结果。     

BQ1010A型单臂刨床进给系统的数控改造设计

论述了ＢＱ１０１０Ａ型单臂刨床数控改造的控制原理，进行了进给系统最佳传动比的计算，完成了控制系统硬件、软件设计及机械部分的改造设计，使刨床的最小进给量由原来的０．６０ｍｍ减小到０．０１ｍｍ，提高了刨床的使用范围和零件的加工精度．该设计方法可以经济地、快速地获得机床精度，提高刨床的性能价格比．     

机床电气的数控化研究

本文首先从两个大的方面介绍了机床电气数控化改造的意义及内容,接着分别就铣床电气数控系统的总体设计与研究、伺服进给系统的设计与研究、主轴部分电气改造设计与研究、数控系统设计程序的简介进行了详细的分析和阐述,最后以结论的形式得出HNC一21MD数控装置在X5032立式铣床控制系统中的设计、研究与应用价值,为企业的发展赢得了不可忽视的经济效益。     

数控钻床自动进给系统设计

本文叙述了对数控钻床开环进给系统的传动设计及其驱动系统硬件电路与主要传动部件滚珠丝杠的设计计算过程。为实现在同一面上加工随机分布的各种孔,设计内容包括自动进给系统的总体结构设计、自动控制系统设计与零部件的设计、验算与选择,并应用单片机对数控系统进行驱动控制设计,实现了两个步进电机的选择控制。文中从机床进给系统的设计角度,初步完成了数控钻床进给系统的设计过程。今后将对该控制系统在精确控制的性能问题上进行完善性的工作,以便有效地完善数控钻床在高速和高精度条件下的微细孔机械加工能力。     

改进设计的TX649B卧式数显铣镗床

T649A卧镗是60年代设计的产品,限于当时机械行业的水平,其进给系统结构设计较为复杂,同时存在机床性能不够稳定、整机噪声较高等问题。为此,我厂对该机床的部分结构进行     

KC 2半自动拉刀刃沟车床

本文简略地介绍 KC2半自动拉刀刃沟车床;从机床的工作原理和半自动工作循环,机床的传动系统,重点介绍了机床的主要机构,最后叙述机床电器控制系统。说明了机床的主要特点是:利用工件未加工表面作为靠模尺的原理实现刀具的跟踪运动;设计独特的锥齿塔齿轮变连机构以实现拉刀的分齿齿距的变换;使用了电磁铁控制的接通机构和其他各传动环节的简单机构,使机床尽可能地结构简化和性能的可靠;机床工作时,运动的复杂过程由较为先进的程序控制系统进行控制,直观而且可靠。     

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of