文献翻译—铸造及其他成形工艺

文献翻译—铸造及其他成形工艺
文献翻译—铸造及其他成形工艺

附录

英文:

Casting and Other Forming Processes

DeGarmo, E. Paul et al. Materials and Processes in Manufacturintg. John Wiley &

Song, 1998. P205-211

Casting

Casting is the introduction of molten metal into a cavity or mold where, upon solidification, it becomes an object whose shape is determined by mold configuration. Casting offers several advantages over other method of metal forming: it is adaptable to intricate shapes, to extremely large pieces, and to mass production; it can provide parts with uniform physical and mechanical properties through out and, depending on the particular material being cast, the design of the part, and the quantity being produced, its economic advantages can surpass other processes.

Categories

Two broad categories of metal-casting processes exist: ingot casting (which includes continuous casting) and casting to shape. Ingot castings are produced by pouring molten metal into a permanent or reusable mold. Following solidification these ingots (or bars, slabs, or billets, as the case may be) are then further processed mechanically into many new shapes. Casting to shape involves pouring molten metal into molds in which the cavity provides the final useful shape, followed only by machining or welding for the specific application.

Ingot casting Ingot castings make up the majority of all metal castings and are separated into three categories: static cast ingots, semi-continuous or direct-chill cast ingots, and continuous cast ingots.

Static cast ingots Static ingot casting simply involves pouring molten metal into a permanent mold. After solidification, the ingot is withdrawn from the mold and the mold can be reused. This method is used to produce millions of tons steel annually.

Semi-continuous cast ingots A semi continuous casting process is employed in

the aluminum industry to produce most of the cast alloys from which rod, sheet, strip, and plate configurations are made. In this process molten aluminum is transferred to a water-cooled permanent mold which has a movable base mounted on a long piston. After solidification has progressed from the mold surface so that a solid "skin" is formed, the piston is moved down. Finally the piston will have moved its entire length, and the process is stopped. Conventional practice in the aluminum industry utilizes suitably lubricated metal molds. However, technological advances have allowed major aluminum alloy producers to replace the metal mold (at least in part) by an electromagnetic field so that molten metal touches the metal mold only briefly, thereby making a product with a much smoother finish than that produced conventionally.

Continuous cast ingots Continuous casting provides a major source of cast material. In the steel and copper industry and is growing rapidly in the aluminum industry. In this process molten metal delivered to a permanent mold, and the casting begins much in the same way as in semi continuous casting. However, instead of the process ceasing after a certain length of time, the solidified ingot is continually sheared or cut into lengths and removed during casting. Thus the process is continuous, the solidified bar or strip being removed as rapidly as it is being cast. This method has many economic advantages over the more conventional casting techniques; as a result, all modem steel mills produce continuous cast products.

Casting to shape Casting to shape is generally classified according to the molding process, molding material or method of feeding the mold. There are four basic types of these casting processes: sand, permanent-mold, die, and centrifugal Sand casting This is the traditional method which still produces the largest volume of cast-to-shape pieces. It utilizes a mixture of sand grains, water, clay, and other materials to make high-quality molds for use with molten metal. This "green sand" mixture is compacted around a pattern (wood, plaster, or metal), usually by machine, to 20-80% of its bulk density. The two halves of the mold (the cope and drag) are closed over cores necessary to form internal cavities, and the whole assembly is weighted or damped to prevent floating of the cope when the metal is poured.

Other casting processes which utilize sands as a basic component are the shell, carbon dioxide, investment casting, ceramic molding and plaster molding processes. In addition, there are a large number of chemically bonded sands which are becoming increasingly important.

Permanent-mold casting Many high-quality castings are obtained by pouring molten metal into a mold made of cast iron, steel, or bronze. Semi permanent mold materials such as aluminum, silicon carbide, and graphite may also be used. The mold cavity and the gating system are machined to the desired dimensions after the mold is cast: the smooth surface from machining thus gives a good surface finish and dimensional accuracy to the casting. To increase mold life and to make ejection of the casting easier, the surface of the mold cavity is usually coated with carbon soot or a refractory slurry; these also serve as heat barriers and control the rate of cooling of the casting. The process is used for cast iron and nonferrous alloys with advantages over sand casting such as smoother surface finish, closer tolerances, and higher production rates.

Die casting A further development of the permanent molding process is die casting. Molten metal is forced into a die cavity under pressures of 100 -100, 000 psi. Two basic types of die-casting machines are hot-chamber and cold-chamber. In the hot-chamber machine, a portion of the molten metal is forced into the cavity at pressures up to about 2, 000 psi. The process is used for casting low-melting-point alloys such as lead, zinc, and tin.

In the cold-chamber process the molten metal is ladled into the injection cylinder and forced into the cavity under pressures which are about 10 times those in the hot-chamber process. High-melting-point alloys such as aluminum-, magnesium-, and copper-base alloys are used in this process. Die casting has the advantages of high production rates, high quality and strength, surface finish on the order of 40—100-microinch rms (root mean square), and close tolerances, with thin sections.

Rheocasting is the casting of a mixture of solid and liquid. In this process the alloy to be cast is melted and then allowed to cool until it is about 50% solid and 50% liquid. Vigorous stirring promotes liquid like properties of this mixture so that it can

be injected in a die-casting operation. A major advantage of this type of casting process is expected to be much reduced die erosion due to the lower casting temperatures.

Centrifugal casting Inertial forces of rotation distribute molten metal into the mold cavities during centrifugal casting, of which there are three categories: true centrifugal casting, semi centrifugal casting, and centrifuging. The first two processes produce hollow cylindrical shapes and parts with rotational symmetry respectively. In the third process, the mold cavities are spun at a certain radius from the axis of rotation; the centrifugal force thus increases the pressure in the mold cavity.

The rotational speed in centrifugal casting is chosen to give between 40 and 60g acceleration. Dies may be made of forged steel or cast iron. Colloidal graphite is used on the dies to facilitate removal of the casting.

Successful operation of any metal-casting process requires careful consideration of mold design and metallurgical factors.

Sheet and Plate Bending

Bending is a method of producing shapes by stressing metal beyond its yield strength, but not past its ultimate tensile strength. The forces applied during bending are in opposite directions, just as in the cutting of sheet metal. Bending forces, however, are spread farther apart, resulting in plastic distortion of metal without failure.

The bending process appears to be simple; yet, in reality, it is a rather complex process involving a number of technical factors. Included are characteristics of the work piece material flow and reactions during various stages of deformation, the effect of tooling design on force required to form the bend, and the type of equipment used.

In the large, varied field of sheet metal and plate fabricating, several types of bending machines are used. Press brakes predominate in shops that process heavy-gage materials, because they are well suited to such applications and also because they are adaptable to other metalworking operations, such as punching, piercing, blanking, notching, perforating, embossing, shearing, and drawing.

工业设计专业英语英文翻译

工业设计原著选读 优秀的产品设计 第一个拨号电话1897年由卡罗耳Gantz 第一个拨号电话在1897年被自动电器公司引入,成立于1891年布朗强,一名勘萨斯州承担者。在1889年,相信铃声“中央交换”将转移来电给竞争对手,强发明了被拨号系统控制的自动交换机系统。这个系统在1892年第一次在拉波特完成史端乔系统中被安装。1897年,强的模型电话,然而模型扶轮拨条的位置没有类似于轮齿约170度,以及边缘拨阀瓣。电话,当然是被亚历山大格雷厄姆贝尔(1847—1922)在1876年发明的。第一个商业交换始建于1878(12个使用者),在1879年,多交换机系统由工程师勒罗伊B 菲尔曼发明,使电话取得商业成功,用户在1890年达到250000。 直到1894年,贝尔原批专利过期,贝尔电话公司在市场上有一个虚拟的垄断。他们已经成功侵权投诉反对至少600竞争者。该公司曾在1896年,刚刚在中央交易所推出了电源的“普通电池”制度。在那之前,一个人有手摇电话以提供足够的电力呼叫。一个连接可能仍然只能在给予该人的名义下提出要求达到一个电话接线员。这是强改变的原因。 强很快成为贝尔的强大竞争者。他在1901年引进了一个桌面拨号模型,这个模型在设计方面比贝尔的模型更加清晰。在1902年,他引进了一个带有磁盘拨号的墙面电话,这次与实际指孔,仍然只有170度左右在磁盘周围。到1905年,一个“长距离”手指孔已经被增加了。最后一个强的知名模型是在1907年。强的专利大概过期于1914年,之后他或他的公司再也没有听到过。直到1919年贝尔引进了拨号系统。当他们这样做,在拨号盘的周围手指孔被充分扩展了。 强发明的拨号系统直到1922年进入像纽约一样的大城市才成为主流。但是一旦作为规规范被确立,直到70年代它仍然是主要的电话技术。后按键式拨号在1963年被推出之后,强发明的最初的手指拨号系统作为“旋转的拨号系统”而知名。这是强怎样“让你的手指拨号”的。 埃姆斯椅LCW和DCW 1947 这些带有复合曲线座位,靠背和橡胶防震装置的成型胶合板椅是由查尔斯埃姆斯设计,在赫曼米勒家具公司生产的。 这个原始的概念是被查尔斯埃姆斯(1907—1978)和埃罗沙里宁(1910—1961)在1940年合作构想出来的。在1937年,埃姆斯成为克兰布鲁克学院实验设计部门的领头人,和沙里宁一起工作调查材料和家具。在这些努力下,埃姆斯发明了分成薄片和成型胶合板夹板,被称作埃姆斯夹板,在1941年收到了来自美国海军5000人的订单。查尔斯和他的妻子雷在他们威尼斯,钙的工作室及工厂和埃文斯产品公司的生产厂家一起生产了这批订单。 在1941年现代艺术博物馆,艾略特诺伊斯组织了一场比赛用以发现对现代生活富有想象力的设计师。奖项颁发给了埃姆斯和沙里宁他们的椅子和存储碎片,由包括埃德加考夫曼,大都会艺术博物馆的阿尔弗雷德,艾略特诺伊斯,马尔塞布鲁尔,弗兰克帕里什和建筑师爱德华达雷尔斯通的陪审团裁决。 这些椅子在1946年的现代艺术展览博物馆被展出,查尔斯埃姆斯设计的新的家具。当时,椅子只有三条腿,稳定性问题气馁了大规模生产。 早期的LCW(低木椅)和DWC(就餐木椅)设计有四条木腿在1946年第一次被埃文斯产品公司(埃姆斯的战时雇主)生产出来,被赫曼米勒家具公司分配。这些工具1946年被乔治纳尔逊为赫曼米勒购买,在1949年接手制造权。后来金属脚的愿景在1951年制作,包括LCW(低金属椅)和DWC(就餐金属椅)模型。配套的餐饮和咖啡桌也产生。这条线一直

铸造成型工艺

名词解释 1.材料成形技术:利用生产工具对各种原材料进行增值加工或处理,材料制备成具一定结构形式和形状工件的方法 2.液态成型:将液态金属浇注到与零件形状相适应的铸型型腔中,待其冷却凝固,以获得毛坯或零件的生产方法 3.逐层凝固:纯金属和共晶成分的合金在凝固中不存在固液两相并存的凝固区,所以固液分界面清晰可见,一直向铸件中心移动(铸铁) 4.糊状凝固:铸件在结晶过程中,当结晶温度范围很宽且铸件界面上的温度梯度较小,则不存在固相层,固液两相共存的凝固区贯穿整个区域(铸钢) 5.同时凝固原则:铸件相邻各部位或铸件各处凝固开始及结束的时间相同或相近,甚至是同时完成凝固过程,无先后的差异及明显的方向性 6.顺序凝固原则:在铸件上可能出现缩孔的厚大部位通过安放冒口等工艺措施,使铸件远离冒口的部位先凝固,然后是靠近冒口的部位凝固,最后才是冒口本身凝固。 7.均衡凝固原则:利用铸铁件石墨的共晶膨胀消除缩松的工艺方式 8.砂型铸造:以型砂(SiO2)为铸型、在重力下充型的液态成形工艺方法 9.金属型铸造:以金属为铸型、在重力下的液态成形方法。 10.熔模铸:以蜡为模型,以若干层耐火材料为铸型材料,成形铸型后,熔去蜡模形成型腔,最终在重力下成形的液态成形方法 11.压力铸:把液态或半液态的金属在高压作用下,快速充填铸型,并在高压下凝固而获得铸型的方法 12.低压铸造:是液态金属在较小的压力(20—80Kpa)作用下,使金属液由下而上对铸型进项充型,并在此压力下凝固成型的铸造工艺 13.反重力铸造:液态金属在与重力相反方向力的作用下完成充型,凝固和补缩的铸造成型 14.离心铸造:将液态金属浇注到高速旋转的铸型中,使金属在离心力的作用下充填型腔并凝固成型的方法 15.消失模铸造:用泡沫塑料制成带有浇冒系统的模型,覆上涂料,用干砂造型,无需取模,直接浇注的铸件方法 16.浇注系统:液态金属流入型腔的通道的总称,通常由浇口杯,直浇道,直浇道窝,横浇道和内浇道组成 17.阻流界面:在浇注系统各组元中,截面积最小的部分称为阻流截面 18.集渣包:横浇道上被局部加大加高的部分 19.浇口比:直浇道,横浇道,内浇道截面积之比 20.热节:在壁的相互连接处由于壁厚增加,凝固速度最慢,最容易形成收缩类缺陷 分型面:两半铸型相互接触的表面。分为平直和曲面。作用:便于造型、下芯和起模具。 21.砂芯:为了起模方便并形成铸件的内腔、孔和铸件外形不能出砂的部位,所采用的砂块 22.芯头:伸出铸件以外不与金属液接触的砂芯部分芯头种类:垂直芯头、水平芯头、特殊结构的芯头 23.冒口:铸型内用于储存金属液的空腔,在铸件凝固过程中补给金属,起到防止缩孔,缩松,排气和集渣的作用 冒口=冒口区+轴线缩松区+末端区 24.冒口的补缩距离:冒口补缩后形成的致密冒口区和致密末端区之和 25.补贴:为实现顺序凝固和增强补缩效果,在靠近冒口的壁厚上补加倾斜的金属块 26.均衡凝固:利用铸铁件石墨的共晶膨胀消除缩松的工艺方法 27.缩孔与缩松:液态合金在冷凝过程中,若其液态收缩和凝固收缩所缩减的容积得不到补充,则在铸件最后凝固的部位形成一些孔洞。大而集中的称为锁孔,细小而分散的称为缩松 28.收缩时间分数:铸铁件表观收缩时间与铸件凝固时间的比值 29.补缩量:铸件从浇注系统,冒口抽吸的补缩液量收缩模数:均衡凝固时均衡点的模数 30.复合材料:由有机高分子,无机非金属和金属等几类不同材料人工复合而成的新型材料。它既保留原组分的主要特征,又获得了原组分不具备的优越性能 31.机械加工余量:在铸件加工表面上流出的、准备切削去的金属厚度。 32.冒口补缩通道:末端多了一个散热面,散热快—构成一个朝向冒口而递增的温度梯度;存在平行于轴线的散热表面,形成一个朝向冒口的楔形的补缩通道 33.工艺出品率:铸件质量占铸件及浇注系统(含冒口)质量的比例 34.反重力铸造:指液态金属在与重力方向相反方向力的作用下完成充型,补缩和凝固过程的铸造成型方法 35.离心铸造:指将液态金属浇入高速旋转的铸型中,使金属在离心力的作用下充填型腔并凝固成型的方法

科技外文文献译文

流动的:一个快速的,多平台的开放源码的同步化多媒体整合语言唱机Dick C.A. Bulterman, Jack Jansen, Kleanthis Kleanthous, Kees Blom and Daniel Benden CWI: Centrum voor Wiskunde en Informatica Kruislaan 413 1098 SJ Amsterdam, The Netherlands +31 20 592 43 00 Dick.Bulterman@cwi.nl 摘要: 本文概述了一个出现在早期的流动性的同步化多媒体唱机。不同于其它同步化的实现,早期的播放器是一个可重组的同步化引擎,可以定制作为一个实验媒体播放器的核心。同步化唱机是一个引用了同步化多媒体引擎并可以集成在一个广泛的媒体播放器的项目。本文是以我们要创造一个新的同步化引擎为动机的综述开始的。然后论述的是早期媒体播放器的核心架构(包括可扩展性,播放器自定义的集成装置)。我们以一个关于我们在windows,Mac,Linux版本应用于台式机以及PDA设备上实施流动性例子的体验的讨论结束。 类别和主题描述符: H.5.2 多媒体的信息系统。 H.5.4 超级文本/超级媒体。 一般词汇: 试验,性能,验证。 关键词: 同步化多媒体整合语言,唱机,公开源代码,演示。 1.动机: 早期公开的同步化媒体播放器是一个非常有特色的公开源代码的同步化 2.0播放器,它以研究团体的意图被使用(在我们的研究团体内外)目的是为了研究项目的团体在需要源代码的时候可以访问生产特性的同步化播放器的网站。它也被用作一个独立的不需要专有的媒体格式的同步化播放器使用,播放器支持一系列同步化2.0配置文件(包括台式机和移动的配置)可以被分配利用在Linux,Macintosh,windows系统的台式机,PDA设备和掌上电脑。 同时现存的几个同步化播放器,包括网络视频播放软件,IE浏览器,小型同步化播放器, GRiNS ,X- GRiNS ,以及各种各样专有移动设备,我们发展流动性唱机有三个原因: 准许制作数字以及个人或者课堂使用中的的全部硬拷贝即时没有提供拷贝权限或者商业性的利益分摊,而且在第一页有这种拷贝的注意事项。服务器上有关于复制以及翻版的分发列表的通知。需要事先明确具体的许可权以及费用。 'MM’04, October 10-16, 2004, New Y ork, New Y ork, USA. Copyright 2004 ACM 1-58113-893-8/04/0010...$5.00. 现有的同步化播放器没有提供一个完整同步化2.0播放器的正确实现。早期的播放器所有的同步化工具,是以同步化2.0语言的属性为基础加上扩展功能能够支持高级的动画以及规范可移动设备以3GPP/PSS-6同步化使用. 所有的同步化播放器都是针对商业SMIL表达专有媒介。早期的播发器使用开源的媒体解码器和开源的网络传输协议,以便播放器可以轻松定制广泛的使用范围的研究计划。 我们的目标是建立一个鼓励发展类似的多媒体研究输出的平台,,我们期望的是一个标准的基线播放器的供给,其他研究人员和开发机构可以集中精力到基线播放器的集成扩展(从新媒体的解码器或新的网络控制算法任何一个中)。这些扩展可以在其它的平台上被共享。 在2004年中期,与螺旋形客户机对照,同时移动到一个GPL核心,早期的播放器支持一个广阔的范围的同步化应用指标构架,它提供了一个准确实现的更完整的同步化语言,它在低资源配置下提供了更好的性能,提供了更多可扩展的媒体播放器架构。它也提供了一个包含所有媒体解码作为部分开放的客户基础。

工业设计外文翻译

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(文档含英文原文和中文翻译) 中英文翻译原文:

DESIGN and ENVIRONMENT Product design is the principal part and kernel of industrial design. Product design gives uses pleasure. A good design can bring hope and create new lifestyle to human. In spscificity,products are only outcomes of factory such as mechanical and electrical products,costume and so on.In generality,anything,whatever it is tangibile or intangible,that can be provided for a market,can be weighed with value by customers, and can satisfy a need or desire,can be entiled as products. Innovative design has come into human life. It makes product looking brand-new and brings new aesthetic feeling and attraction that are different from traditional products. Enterprose tend to renovate idea of product design because of change of consumer's lifestyle , emphasis on individuation and self-expression,market competition and requirement of individuation of product. Product design includes factors of society ,economy, techology and leterae humaniores. Tasks of product design includes styling, color, face processing and selection of material and optimization of human-machine interface. Design is a kind of thinking of lifestyle.Product and design conception can guide human lifestyle . In reverse , lifestyle also manipulates orientation and development of product from thinking layer.

工业设计外文翻译---不需要设计师的设计

Design Without Designers 网站截图: https://www.360docs.net/doc/9812375674.html,/baidu?word=%B9%A4%D2%B5%C9%E8%BC%C6%D3%A2%CE%C4%CE%C4%CF%D 7&tn=sogouie_1_dg 原文: Design Without Designers I will always remember my first introduction to the power of good product design. I was newly arrived at Apple, still learning the ways of business, when I was visited by a member of Apple's Industrial Design team. He showed me a foam mockup of a proposed product. "Wow," I said, "I want one! What is it?" That experience brought home the power of design: I was excited and enthusiastic even before I knew what it was. This type of visceral "wow" response requires creative designers. It is subjective, personal. Uh oh, this is not what engineers like to hear. If you can't put a number to it, it's not important. As a result, there is a trend to eliminate designers. Who needs them when we can simply test our way to success? The excitement of powerful, captivating design is defined as irrelevant. Worse, the nature of design is in danger. Don't believe me? Consider Google. In a well-publicized move, a senior designer at Google recently quit, stating that Google had no interest in or understanding of design. Google, it seems, relies primarily upon test results, not human skill or judgment. Want to know whether a design is effective? Try it out. Google can quickly submit samples to millions of people in well-controlled trials, pitting one design against another, selecting the winner based upon number of clicks, or sales, or whatever objective measure they wish. Which color of blue is best? Test. Item placement? Test. Web page layout? Test. This procedure is hardly unique to Google. https://www.360docs.net/doc/9812375674.html, has long followed this practice. Years ago I was proudly informed that they no longer have debates about which design is best: they simply test them and use the data to decide. And this, of course, is the approach used by the human-centered iterative design approach: prototype, test, revise. Is this the future of design? Certainly there are many who believe so. This is a hot topic on the talk and seminar circuit. After all, the proponents ask reasonably, who could object to making decisions based upon data? Two Types of Innovation: Incremental Improvements and New Concepts In design—and almost all innovation, for that matter—there are at least two distinct forms. One is

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科技文献翻译电子档答案

科技文献翻译考试试题 1.大型飞机自动化装配技术 摘要:本文简述了大型飞机及其结构特点,通过比较人与机器两种装配系统的特性,分析装配自动化水平与装配成本等诸多因素的关系曲线,指出了自动化装配技术在保证大型飞机长寿命、高效率、低成本研制和生产等方面的意义;对外国大型飞机的装配自动化发展状况进行了综述,简要分析了国外发展的几种主要自动化装配系统,总结了国外大型飞机的自动化装配水平;对西方国家在大型飞机自动化装配中采用的先进的装配理念和方法,如决定性装配方法等进行了概述。最后针对国内自动化装配水平低的现状和大型飞机研制和生产的需求,提出了发展模块化结构的自动化装配系统、贯彻并行工程理念实现面向制造和面向装配的设计等发展建议。 关键词:自动化装配;大型飞机;长寿命;柔性装配;模块化;决定性装配 1. Automatic Assembly Technology for Large Aircraft Abstract: This paper aims at the large

assembly system, carrying out the means of concurrent engineering and realizing the designs for manufacturing and assembly. Key words: automatic assembly; large aircraft; long life; flexible assembly; modularization; determinant assembly 2.基于SAT的快速电路时延计算 摘要:针对现有的基于时间展开电路求解时延算法在电路规模较大或者时延模型精度较高时效率较低的问题,提出一种基于子电路抽取的电路时延计算方法。基于展开电路,通过分析输出端约束找到相关的输出端,利用回溯抽取与这些输出端相关的逻辑锥子电路,并在子电路而不是在展开电路上进行求解。由于抽取的子电路的规模远小于展开电路的规模,加速r求解过程;同时提出了抽象电路的概念,并分析了抽取子电路的同构特性。通过在抽象电路上进行预处理得到学习子句,从而可以利用学习子句加速每一次的SAT求解过程。在ISCA85和ISCA89电路上的实验结果表明,采用文中方法使得电路时延的求解效率平均提高了约8倍。

工业设计专业英语第三版部分翻译

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娱乐楼房,例如商场电影院,工厂,甚至于新的豪华游轮,它也被利用于在1933年芝加哥展览之中。艺术装饰风格开始象征着高效率的现代化生活和新的生活理念,这种动人的方式随着人们对时尚性和社会地位的追求与渴望,艺术装饰风格得到了大量消费者的高度喜爱地位。 艺术装饰的大量应用伴随着消费产品的需求。但是,从不好的方而来看,艺术装饰风格只是作为一种中档的艺术手法,来装饰非常廉价的商品甚至留有一种杂乱的感觉。在英国有一群针对低端市场开发产品的地毯制造商,他们意识到了这个新潮流里的商业潜力。 但是,这些地毯制造商也很注意他们消费群里的保守心理,因此,即使是在一块地毯里的花紋也会出现那些很传统的1案象是老式的叶子造型和较灰暗的颜色。这种设计的消费市场不同于那些要不就是现代型或是完全传统的设计方案。1920年代到30年代,英国都铎王室的一些新居住者和新建筑的到来,使工艺美术运动和现代风格可以较为自由的发展和合理的被采用.这些各异的艺术风格也被按照使用者的喜好不同加入到地毯的设计之中。在20世纪30年代的中期,改良过的艺术装饰风格在数不清的家居装饰里都可以看到"在花园门饰上,无线电机的面板装饰上,阿芝台克寺庙的壁炉上和那些扶手椅和沙发的几何形体上。"

英文科技文献及翻译

外文翻译 DC GENENRATORS 1. INTRODUCTION For all practical purposes, the direct-current generator is only used for special applications and local dc power generation. This limitation is due to the commutator required to rectify the internal generated ac voltage, thereby making largescale dc power generators not feasible. Consequently, all electrical energy produced commercially is generated and distributed in the form of three-phase ac power. The use of solid state converters nowadays makes conversion to dc economical. However, the operating characteristics of dc generators are still important, because most concepts can be applied to all other machines. 2. FIELD WINDING CONNECTIONS The general arrangement of brushes and field winding for a four-pole machine is as shown in Fig.1. The four brushes ride on the commutator. The positive brusher are connected to terminal A1 while the negative brushes are connected to terminal A2 of the machine. As indicated in the sketch, the brushes are positioned approximately midway under the poles. They make contact with coils that have little or no EMF induced in them, since their sides are situated between poles. Figure 1 Sketch of four-pole dc matchine The four excitation or field poles are usually joined in series and their ends brought out to terminals marked F1 and F2. They are connected such that they produce north and south poles alternately. The type of dc generator is characterized by the manner in which the field

铸造成形工艺理论基础

第一篇金属的铸造成形工艺 第一章铸造成形工艺理论基础 §1-1 概述 金属液态成形工艺——铸造、液态冲压、液态模锻等 铸造(最广泛)——将液态合金浇注到与零件的形状、尺寸相适应的铸型空腔中,使其冷却凝固,得到毛坯或零件的成形工艺(生产方法)。 一、特点 1.能制成形状复杂、特别是具有复杂内腔的毛坯: 如:阀体、泵体、叶轮、螺旋浆等 2.铸件的大小几乎不受限制,重量从几克到几百吨 3.常用的原材料来源广泛,价格低廉,成本较低,其应用及其广泛 (如:机床、内燃机中铸件70~80%,农业机械40~70%) 但铸造生产过程较复杂,废品率一般较高,易出现浇不足,缩孔,夹渣、气孔、裂纹等缺陷。 二、分类 铸造 砂型铸造——90%以上,成本低 特种铸造——熔模、金属型、压力、低压、离心 质量、生产率高,成本也高 §1-2 铸造的工艺性能 工艺性能——符合某种生产工艺要求所需要的性能 铸造性能——合金的流动性、收缩性、吸气性、偏析等 一、合金的流动性 1.概念 指液态合金本身的流动能力,它是合金主要的铸造性能,流动性愈强,愈便于浇铸出轮廓清晰、薄而复杂的铸件。 同时,有利于非金属夹杂物和气体的上浮与排除,还有利于对合金冷凝过程所产生的收缩进行补缩。 流动性不好——浇不足、冷隔 [注]:流动性的测定——“螺旋形试样”(图1-1)

流动性愈好,浇出的试样愈长 灰铸铁、硅黄铜最好,铝合金次之,铸钢最差 2.影响合金流动性的因素 ①化学成分 共晶成分合金的结晶是在恒温下进行的,此时,液态合金从表层逐层向中心凝固,由于已结晶的固体层内表面比较光滑(图1-3a)对金属液的阻力较小。同时,共晶成分合金的凝固温度最低(铁碳合金状态图)。 相对说来,合金的过热度(浇注温度与合金熔点之温差)大,推迟了合金的凝固,故共晶成分合金的流动性最好。 除纯金属外,其它成分合金是在一定温度范围的逐步凝固,即经过液、固并存的两相区。此时,结晶是在截面上的一定宽度的凝固区内同时进行的,由于初生的“树枝状”晶体,使已结晶固体层的表面粗糙(图1-3b)所以,合金的流动性变差。 共晶生铁,流动性好。 [注]:降低金属液粘度——提高流动性 如加P—铸铁凝固温度、粘度↓→流动性好 但引起冷脆性(性能要求不高的小件) S→MnS→内摩擦(粘度↑)→流动性↓ ②浇注条件 浇注温度——温度↑→粘度↓过热度↑,保持液态时间长→流动性好,但过高→收缩增大,吸气增多,氧化严重→缩孔、缩松、气孔、粘砂等 控制浇注温度:灰铸铁:1200~1380℃ 铸铜:1520~1620℃ 铝合金:680~780℃ 浇注压力——压力愈大,流动性愈好 增加直浇口高度或采用压力铸造、离心铸造 ③铸型充填条件 铸型的蓄热能力——铸型材料的导热系数和比热愈大,对液态合金的“激冷” 能力愈强,流动性差。如:金属型比砂型铸造更容易产生浇不足等缺陷。 铸型中气体——在金属液的热作用下,型腔中气体膨胀,腔中气体压力增大——流动性差(阻力大) 改善措施:使型砂具有良好的透气性,远离浇口最高部位开设气口。 二、合金的收缩性

金属成形方法大全.docx

金属成形方法大全 铸造 液态金属浇注到与零件形状、尺寸相适应的铸型型腔中,待其冷却凝固,以获得毛坯或零件的生产方法,通常称为金属液态成形或铸造。 工艺流程:液体金属→充型→凝固收缩→铸件 工艺特点: 1、可生产形状任意复杂的制件,特别是内腔形状复杂的制件。 2、适应性强,合金种类不受限制,铸件大小几乎不受限制。 3、材料来源广,废品可重熔,设备投资低。 4、废品率高、表面质量较低、劳动条件差。 铸造分类: (1)砂型铸造(sand casting) 在砂型中生产铸件的铸造方法。钢、铁和大多数有色合金铸件都可用砂型铸造方法获得。 工艺流程: 技术特点: 1、适合于制成形状复杂,特别是具有复杂内腔的毛坯; 2、适应性广,成本低; 3、对于某些塑性很差的材料,如铸铁等,砂型铸造是制造其零件或,毛坯的唯一的成形工艺。 应用:汽车的发动机气缸体、气缸盖、曲轴等铸件 (2)熔模铸造(investmentcasting) 通常是指在易熔材料制成模样,在模样表面包覆若干层耐火材料制成型壳,再将模样熔化排出型壳,从而获得无分型面的铸型,经高温焙烧后即可填砂浇注的铸造方案。常称为“失蜡铸造”。

工艺流程: 优点: 1、尺寸精度和几何精度高; 2、表面粗糙度高; 3、能够铸造外型复杂的铸件,且铸造的合金不受限制。 缺点:工序繁杂,费用较高 应用:适用于生产形状复杂、精度要求高、或很难进行其它加工的小型零件,如涡轮发动机的叶片等。 (3)压力铸造(die casting) 利用高压将金属液高速压入一精密金属模具型腔内,金属液在压力作用下冷却凝固而形成铸件。 工艺流程: 优点: 1、压铸时金属液体承受压力高,流速快 2、产品质量好,尺寸稳定,互换性好; 3、生产效率高,压铸模使用次数多; 4、适合大批大量生产,经济效益好。 缺点: 1、铸件容易产生细小的气孔和缩松。 2、压铸件塑性低,不宜在冲击载荷及有震动的情况下工作; 3、高熔点合金压铸时,铸型寿命低,影响压铸生产的扩大。 应用:压铸件最先应用在汽车工业和仪表工业,后来逐步扩大到各个行业,如农业机械、机床工业、电子工业、国防工业、计算机、医疗器械、钟表、照相机和日用五金等多个行业。 (4)低压铸造(low pressure casting) 指使液体金属在较低压力(0.02~0.06MPa)作用下充填铸型,并在压力下结晶以形成铸件的方法。

工业设计外文翻译---中国要有自己的创新之道

1.Creative China must find its ownPath 网站截图: https://www.360docs.net/doc/9812375674.html,/baidu?word=%B9%A4%D2%B5%C9%E8%BC%C6%D3%A2%CE%C4 %CE%C4%CF%D7&tn=sogouie_1_dg 原文: Creative China must find its own Path Justin 0'Connor It is commonly said that China needs to ‘catch-up’ with `the west' or the `developed world'. This phrase implies a singular path; there may be short cuts and `late-comer advantages' but the destination一a modern, developed country一is the same. But just when it seems China is within touching distance, the `developed world' changes the definition of what it is to be `developed' and puts more obstacles in the path of those trying to catch-up. In English we call this `moving the goal-posts'. After manufacturing, services and high-technology seemed to present clear goals for China, the cultural creative industries arrive as the new `value-added' product and service sector, posing yet more problems for the country's policy-makers. Many in the West have argued that China will take a long time to catch-up in these areas and that this provides a new source of competitive advantage to the West. Indeed, for some, the absence of a competitive cultural creative industries sector is evidence that China is not, and maybe can never be, fully `developed'. Much of this can be dismissed as another example of the West's superiority complex; however, there can be no doubt that the cultural creative industries present great possibilities but also great challenges for China. These industries一from visual and performing arts, to recorded music, film and TV, to digital animation and new media services, through to fashion, design and architecture一are highly creative and innovative products and services, relying on complex flows of knowledge and intellectual property. They are also cultural or symbolic products that reflect and influence our pleasures and ambitions, and our individual and collective sense of meaning and identity. For these reasons all nations have sought to protect and develop their own national culture and traditions by investing in cultural infrastructure and expertise. In the second half of the twentieth century this was expanded beyond `the arts,一galleries,

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