机床几何精度修理实操研究

机床修理包括机床几何精度和机床性能的修理,机床几何精度是尺寸链关系的具体体现,是非常关键的因素。修理机床精度时,合理地选择修理基准面和修理工艺顺序,对保证机床修理精度和提高修理效率有很大意义。     

立式铣销加工中心结构静动态分析

利用PRO/E建立了XH715立式加工中心的三维模型,通过ANSYS软件建立有限元整机分析模型,时XH715立式加工中心进行静、动态分析,确定机床的立柱和底座对机床动态性能的影响.机床立柱的动态摆动和扭转变形是影响机床动态性能的主要因素.对立柱和底座的结构进行改进,可有效地提高机床的动态性能.     

浅析机床加工误差的原因及消除方法

加工精度是衡量机器零件加工质量的一个重要指标.由于影响加工精度的因素诸多,不易有效控制,因此提高加工精度减小加工误差较为困难,研究机床加工过程误差的产生及防止对提高机床加工精度有着重要的意义.     

金属切削机床爬行因素分析与消除措施

重点分析金属切削机床爬行故障形成因素及消除措施.     

浅谈机床大修与数控化改造

1 产生与发展的社会、经济基础 　　机床长期运转甚至超负荷使用,同时又缺少认真的维修与保养,会造成机床严重磨损,丧失精度;由于新产品制造的需要,原有机床性能已不能满足使用要求,急需更新升级改造;由于世界计算机及网络技术的飞速发展,造成数控系统、驱动系统厂的产品更新加快,原有产品过早停产,给备件更换与维修带来一定困难;况且数控系统的使用寿命一般在5～10年而我国大多数机床都在超期服役,这些诸多因素都需要对机床进行大修及数控化升级改造.……     

影响机械加工精密度的原因分析

影响机械加工精度的因素有很多,在诸多误差因素中,机床的几何误差、工艺系统的受力变形和受热变形占有突出的位置,通过了解造成误差因素的原因,可以使工件的加工达到质量要求.     

滚压螺纹形成尺寸链的研究

通过对双滚柱机床滚压螺纹时形成尺寸链的分析,找出影响滚压螺纹精度的因素,并提出了解决途径.     

数控机床的几何误差分析研究

本文主要介绍多体系统理论在数控机床几何误差建模方面的应用,通过对三坐标加工中心的几何误差建模研究,分析对机床精度的影响因素。     

机床机械结合面接触刚度模型研究概况

结合面接触问题对数控机床动态特性影响非常大,是决定机床系统总刚度和总阻尼的主要因素.本文总结了机床机械结合面接触刚度研究中常用的三种模型,即赫兹接触模型、G-W统计接触模型和分形接触模型,并根据三维W-M函数,利用Matlab仿真模拟了表面的三维粗糙形貌,分析了分形参数G和D的含义.     

提高机床刚度的措施

机床的刚度是指机床在负载的作用下抵制变形的一种能力。如果机床刚度不够,那么在切削力及机床自身重力等作用下,机床的各部件因为受力而变形,导致工件和刀具相对位置的变化,从而影响机床的加工精度。本文着重从多方面探讨机床刚度提高的基本措施。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

胡主席在印度,我却在中国

Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer.     

STORIES

正A One day a pig went to the stable(马棚)to see his good friend,an oldhorse,and was going to stay there forthenight.Night came and it was time forsleep.The pig went into the straw heap(稻草堆)and lay comfortably.A longtime passed,but the horse was stillstanding there and did not move.Thepig asked the horse why he did not go tosleep."Standing like this is the begin-ning ofsleeping,"answered the horse.     

巧妙引语(英文)

正1.Any fool can count the seeds in an apple.Only God can count all the apples in one seed.2.Happy families are all alike;every unhappy family is unhappy in its own way.3.Memories are the key not to the past,but to the future.4.Sometimes in the dark you see what you want to see.5.There is a great difference between     

Information for Authors

正Scope and Policy The Journal of Chongqing University-English Edition(JCQU-E)is a peerreviewed journal publishing research articles in multiple disciplines of science and technology,covering civil and environmental engineering,chemical engineering,biotechnology,mechanical and electrical engineering,computer and data processing,mining,metallurgy,materials science,and interdisciplines thereof.