机械翻译
- 格式:docx
- 大小:41.38 KB
- 文档页数:16
机器翻译及其翻译步骤机器翻译(MachineTranslation,MT),指的是由电脑程序实现的自动文字翻译技术,它可以在不进行人工介入的情况下,将源文自动翻译成目标语言。
机器翻译技术已经成为翻译领域最受关注的一个话题,它具有准确、快速等优点,可以有效解决因文字的不通而造成的误解和误传的现象。
机器翻译的步骤包括:分词、语法分析、句子改写、翻译完成。
首先是分词,它指的是将一句话中的汉字分解成单独的词,以便电脑程序能够识别该句的意思。
在机器翻译中,分词是翻译的关键步骤,因此分词精准度的高低直接影响翻译结果的准确性与可信度。
接着是语法分析,它指的是利用若干文字学知识,运用语法规则对汉字分解出来的词语及短语进行解析,以确定句子中词语的排列关系及句法结构,这也是机器翻译的一个关键步骤。
紧接着是句子改写,它是基于语法分析的基础上,利用源语言的语法结构与目标语言的语法结构差别,将句子改写成适用于目标语言的形式,这一步将影响最终翻译结果的准确性。
最后是翻译完成,它是机器翻译中最关键的步骤,也是传统机器翻译中最不可缺少的步骤。
翻译完成是根据句子改写的基础上,按照源语言的意思转译成目标语言,将最终的翻译结果输出来。
机器翻译技术的发展,使得准确快速的机器翻译变得可能。
由于它比传统的人工翻译更加快捷,容易被广泛的应用,如在海外文字交流中,可以有效处理中文和英文等。
此外,机器翻译也可以被应用于机器翻译系统中,自动生成多种语言之间的相互翻译,便于用户阅读多种不同语言文章,从而更好的了解多元化的文化和思想。
综上所述,机器翻译是一种很重要的技术,不仅可以提高翻译的准确度,而且还可以提高翻译的速度。
它的应用广泛,可以解决许多问题,是人类获取和传播资讯的重要途径。
然而,机器翻译仍有一定的局限性,尤其是文字表达比较模糊时,它的准确性就不高,需要使用到人工翻译。
所以,未来,结合机器翻译和人工翻译,可以更好的帮助人们进行跨语言的文字交流。
机器翻译方法机器翻译(Machine Translation,MT)是指利用计算机技术实现自然语言之间的翻译。
随着人工智能技术的快速发展,机器翻译已经成为解决语言交流障碍的有效工具。
本文将介绍几种常见的机器翻译方法,并分析它们的优缺点。
一、基于规则的基于规则的机器翻译方法是早期机器翻译技术的主要方法之一。
它通过事先构建一系列的翻译规则,然后根据这些规则将源语言文本转换成目标语言文本。
这种方法需要大量的人工工作,主要包括:1. 构建词汇库:将源语言词汇与目标语言词汇一一对应。
2. 编写规则:根据语法规则和词汇库,编写一系列的翻译规则。
3. 设计规则匹配算法:将源语言文本与规则进行匹配,并生成目标语言文本。
优点:基于规则的机器翻译方法可以实现精确的翻译,尤其在语法规则复杂的语言对之间效果较好。
缺点:构建规则和词汇库需要耗费大量时间和人力,且对语言灵活性要求较高,无法处理多义词和歧义的情况。
二、基于统计的基于统计的机器翻译方法通过分析大规模的双语语料库,学习源语言与目标语言之间的统计规律,从而实现自动翻译。
主要步骤包括:1. 建立双语语料库:收集大规模的源语言和目标语言平行语料,如新闻报道、书籍等。
2. 分词与对齐:将源语言和目标语言文本进行分词,并进行句子级别的对齐。
3. 训练模型:利用统计算法,根据对齐的双语语料库,学习源语言和目标语言之间的翻译模型。
4. 解码翻译:根据学习到的翻译模型,将源语言文本翻译成目标语言文本。
优点:基于统计的机器翻译方法可以自动学习源语言和目标语言之间的翻译规律,无需人工构建规则和词汇库。
缺点:对于生僻词和长句等复杂情况,效果不如基于规则的机器翻译方法。
三、基于神经网络的近年来,随着深度学习的广泛应用,基于神经网络的机器翻译方法逐渐兴起。
该方法通过构建深层神经网络模型,直接将源语言文本映射到目标语言文本,实现端到端的翻译。
主要步骤包括:1. 构建编码器-解码器模型:编码器将源语言文本映射到一个语义空间,解码器将语义空间中的信息转换为目标语言文本。
机器翻译的工作原理机器翻译(Machine Translation,MT)是一种通过计算机程序将一种自然语言的文本转化为另一种自然语言的文本的技术。
随着人工智能的发展,机器翻译在跨语言交流和信息传递中发挥着越来越重要的作用。
那么,机器翻译的工作原理是什么呢?机器翻译的工作原理可以大致分为两个阶段:语言分析和语言生成。
在语言分析阶段,机器翻译系统会对源语言文本进行分析和理解,以获取其中的语义和结构信息。
在语言生成阶段,系统会根据分析得到的信息,生成与源语言文本等价的目标语言文本。
首先,让我们看看语言分析阶段。
在这个阶段,机器翻译系统会对源语言文本进行词法分析、句法分析和语义分析。
词法分析是指将源语言文本划分为一个个词汇单位,这些词汇单位可以是单词、短语或者更大的语言单位。
句法分析是指分析句子的结构和语法关系,以理解句子中各个成分之间的关系。
语义分析是指理解句子的意义和语义关系,以获取句子的语义信息。
为了进行语言分析,机器翻译系统通常会使用统计机器翻译(Statistical Machine Translation,SMT)或神经机器翻译(Neural Machine Translation,NMT)等方法。
在统计机器翻译中,系统会根据大规模的双语平行语料库,学习源语言和目标语言之间的映射关系,以便在翻译时进行参考。
而在神经机器翻译中,系统会使用深度神经网络来建模源语言和目标语言之间的映射关系,以实现更加准确和流畅的翻译。
接下来,让我们来看看语言生成阶段。
在这个阶段,机器翻译系统会根据语言分析得到的信息,生成与源语言文本等价的目标语言文本。
这个过程通常涉及到词汇替换、句法重组和语义转换等操作。
词汇替换是指将源语言文本中的词汇替换为目标语言中的对应词汇。
句法重组是指根据目标语言的语法规则,重新组织句子的结构和语法关系。
语义转换是指根据目标语言的语义规则,转换句子的意义和语义关系。
在语言生成阶段,机器翻译系统通常会使用一些规则和模型来帮助生成目标语言文本。
机械词汇的英语翻译(U-Z)u bend u 形管u bolt u 形螺栓u ir on 槽钢u piec e 双肘管u pipe u形管u tube u 形管u tube manometer u 形压力计uec m超声电解加工uedm 超声电火花加工ultimate analysis 元素分析ultimate load 极限负荷ultimate load design 极限载荷设计ultimate pr essur e极限压力ultimate str ength 极限强度ultimate str ess 极限应力ultimate vac uum 极限真空度ultr ac entrifuge 超离心机ultr ahigh pr essure 超高压ultr ahigh speed machining 超高速机械加工ultr ahigh strength steel 超高强度钢ultr ahigh vacuum 超高真空ultr alow electrode wear machining 超低损耗加工ultr am icr oscope 超高倍显微镜ultr aprecision machining 超精密加工ultr asoinc lapping 超声研磨ultr asonic atom izer 超声雾化器ultr asonic cleaning 超声波清洗ultr asonic drilling 超声钻法ultr asonic drilling mac hine超声波钻床ultr asonic edm超声电火花加工ultr asonic electr o dischar ge mac hining 超声电火花加工ultr asonic electr ochemical mac hining 超声电解加工ultr asonic flaw detector 超声波探伤仪ultr asonic flow meter 超声波量计ultr asonic gener ator 超声波振荡器超声波发生器ultr asonic inspection 超声波探伤法ultr asonic mac hine 超声波加工机ultr asonic mac hining 超声波加工ultr asonic metal for ming 超声塑性加工ultr asonic m icr oscope 超声波显微镜ultr asonic perfor ating mac hine 超声波钻床ultr asonic perfor ation 超声钻法ultr asonic slicing mac hine超声切片机床ultr asonic soldering 超声波针焊ultr asonic testing 超声波探伤法ultr asonic thic kness gage超声波测厚仪ultr asonic vibr ation c utting 超声振动切削ultr asonic wave超声波ultr asonic welding 超声波焊接ultr aviolet r adiation 紫外线辐射ultr aviolet r ays 紫外线unattended oper ation 无人值班的运行unbalanc e 不平衡unbalanc e indic ator 不均衡指示器unbalanc e moment 不平衡力矩unbalanc e toleranc e容许不平衡量unbalanc ed mass 不均衡质量unc oiler 展卷机undamped oscillation 非衰减振荡undamped vibration 非衰减振荡underc arriage 起落架underc ooling 过冷undercutting 根切underfeed furnac e 下部供燃料炉underfr ame 底架under ground gasific ation 地下气化under ground r ailway 地下铁道under ground water 地下水underload 欠载under shot wheel 下射水轮under size 筛下产品undervoltage relay 低电压继电器underwater c utting 水下切割underwater r obot 水中机扑;水下机扑underwater welding 水下焊接undulatory motion 波动unequal angle 不等边角钢unfinished bolt 毛螺栓unhooking 摘钩uniaxial str ess 单向应力unifor m acc eler ation 等加速度unifor m c ircular motion 等速圆周运动unifor m distribution 均匀分布unifor m flow 均匀流unifor m load 均匀负荷unifor m motion 等速运动unifor m movement 等速运动unifor m pr essur e 均匀压力unifor m sc ale 均匀标度unifor m velocity 等速度unifor m ity 均匀性unifor m ly acceler ated motion 等加速度运动unifor m ly distributed load 等分布荷重unifor m ly r etarded motion 匀减速运动union nut 联管螺帽unit 单位unit bor e system 基孔制unit built machine tool 组合机床unit c ell 单位晶格unit c ooler 冷却机组unit of measur ement 测量单位unit of toler anc e公差单位unit shaft system 基轴制unit type head 动力头unit vector 单位矢量universal c huc k 自动定心卡盘universal dividing head 万能分度头universal drilling machine 万能钻床universal gas c onstant 通用气体常数universal gr avitation 万有引力universal grinder 万能磨床universal industrial r obot 万能工业机扑universal j oint 万向接头universal j oint drive万向节传动universal j oint for k 万向节叉universal j oint shaft 万向节轴universal j oint yoke 万向节叉universal mac hine tool 通用机床universal measuring m icr osc ope万能测定显微镜universal miller 万能铣床universal milling mac hine万能铣床universal screw wrench 活动]扳手universal testing mac hine万能材料试验机universal tool and cutter grinder 万能工具磨床unloaded weight 空车重量unloader卸荷阀unloader valve 卸荷阀unloading 卸荷;卸载unloading valve 卸荷阀unmanned aircr aft 无人驾驶飞机unmanned factory 无人工厂unmanned manufactur e无人生产过程unmanned oper ation 无人值班的运行unmanned war ehouse无人仓库unrivet 起铆钉unsatur ated c ompound 不饱和化合物unsatur ated vapor 末饱和蒸汽unscr ew 松螺丝unscr ewing 拧下unsolder 拆开焊缝unsprung weight 弹簧下重量unstable equilibrium 不稳定平衡unstable state 不稳定状态unsteady flow 非定常流不稳定流unsteady heat conduction 不稳定导热up m illing 逆铣up stroke 上升冲程upc urrent 上升气流updr aft 上升气流upflow 上升气流upper dead center 上死点upper deviation 上偏差upper die 上模upper lim it 上限upper slide 上滑板upright drilling mac hine 立式钻床upset butt welding 电阻对焊接upset welding 电阻对焊接upsetter 锻头机upsetting 镦粗upsetting machine 锻头机upsetting test 镦粗试验uptake flue 上升烟道ur anium 铀ur anium enrichment 铀浓缩ur anium fuel 铀燃料ur anium hexafluoride六氟化铀ur anium oxide 氧化铀ur anium r eactor 铀反应堆urban bus 市区公共汽车urea r esin 尿素尸urgency stop 紧急停止uric acid 尿酸used air 废气used c ar 旧汽车used lubric ating oil 废油used sand 旧砂useful ener gy 有效能useful horsepower 有效功率useful load 有效负载useful wor k有效功user pr ogr am 用户程序user's manual 使用说瞄usf 超声塑性加工usl 超声研磨utility aircr aft 通用飞机utility boiler 动力锅炉utilization coefficient 利用率utilization factor 利用率uvc 超声振动切削v belt 三角皮带v belt drive 三角皮带传动v block v 形铁v block br ake 楔形闸v engine v 形发动机v gr oove br ake 楔形闸v guide v 形导轨v pulley 三角皮带轮v sec m 立式电解成形机v tail 蝶形尾部v thr ead 三角螺纹v type engine v型发动机v type tail v 形尾翼vacc um meter 真空计vac uum 真空vac uum annealing 真空退火vac uum arc fur nac e真空电弧炉vac uum bottle 热水瓶vac uum br ake 真空制动器vac uum c apper 真空封瓶器vac uum c apping machine 真空封瓶器vac uum c asting 真空铸造vac uum c ement 真空封泥vac uum c hamber 真空室vac uum c huc k 真空卡盘vac uum cleaner 吸尘器vac uum degassing 真空除气vac uum distillation 真空蒸馏vac uum drying 真空干燥vac uum evapor ation 真空蒸发;真空涂膜vac uum evapor ator 直空蒸发器;真空涂膜器vac uum filler 真空填充器vac uum filter 真空过滤机vac uum filtr ation 真空过滤vac uum for m ing 真空成形vac uum freeze drying 真空冷冻干燥vac uum freezing 真空冷冻vac uum fusion 真空熔化vac uum gauge 真空计vac uum gr ease 真空润滑脂vac uum gripper 真空钳子vac uum hose 真空软管vac uum ignition adva nc er 真空点火提前装置vac uum impr egnation 真空浸渍vac uum indic ator 真空计vac uum induction furnac e 真空感应炉vac uum lamp 真空灯vac uum lifting device 真空提升装置vac uum measur ement 真空测量vac uum measuring instrument 真空计vac uum melting 真空熔化vac uum metallizing 真空镀敷vac uum metallurgy 真空冶金vac uum molding 真空成形vac uum oil 真空油vac uum pac kaging machine 真空包装器vac uum pump 真空泵vac uum r efriger ating mac hine真空冷冻机vac uum r eservoir 真空罐vac uum seal 真空密封vac uum seamer 罐头折边封盖机vac uum sintering 真空烧结vac uum system 真空系统vac uum tank真空罐vac uum tec hnique 真空技术vac uum test 真空试验vac uum tight 真空密封的vac uum tr ap 真空阱vac uum tube 真空管vac uum tube r ectifier 真空整流vac uum tube voltmeter 真空管电压表value 值valve 阀valve ar m 阀杆valve body 阀体valve bonnet 阀盖valve box 阀箱valve c ase 阀箱valve c asing 阀箱valve c hest 阀室valve c oc k阀栓valve c over 阀盖valve diagr am 阀动图valve follower 气门挺杆valve gear 阀动装置valve grinding 磨阀valve guard 阀档板valve guide 阀导承valve head 气门头valve in head engine顶阀式发动机valve lap 阀重叠valve lever 阀杆valve lift 阀升程valve lift curve 阀升程图valve lift diagram 阀升程图valve lifter 气门挺杆valve lifter guide阀挺杆导承valve mec hanism阀动装置valve needle 阀针valve overlap 阀重叠valve plate 阀板valve port 阀口valve position 阀位valve push rod 推阀杆valve r oc ker ar m 气阀摇杆valve r oc ker ar m shaft 阀摇臂轴valve r oc ker br ac ket 阀摇臂轴托架valve r oc ker pedestal 阀摇臂轴托架valve r oc ker shaft 阀摇臂轴valve r od 阀杆valve seat 阀座valve seating 磨阀valve setting 阀蝶valve spring 阀弹簧valve stem 阀杆valve str oke 阀升程valve tappet 气门挺杆valve tappet clear anc e气门挺杆间隙valve tappet guide阀挺杆导承valve tim ing 阀定时valve tim ing gear 阀定时装置valveless engine 无气门式发动机van 箱式货车van der waals' equation 范德瓦耳斯方程vanadium钒vanadium steel 钒钢vane 叶片vane anemometer 翼式风速计vane c ompr essor 叶片式压缩机vane flowmeter 转子式量表vane motor 叶轮式油压马达vane pump 叶轮泵vane wheel 叶轮vaned diffuser 叶片式扩散器vaneless diffuser 无叶片式扩散器无导连的扩压器vapoize 蒸发vapor 蒸汽vapor cycle 蒸气循环vapor loc k 蒸汽汽塞vapor pr essur e 蒸汽压力vapor pump 蒸汽喷射泵vaporimeter 蒸气压力表vaporization 蒸发vaporizer 蒸发器vapour 蒸汽variable 变数variable acceler ation 可变加速度variable c apacitor 可变电容器variable c ondenser 可变电容器variable delivery pump 可变容积泵variable density wind tunnel 变密度风洞variable displacement motor 可变排量马达variable displacement pump 可变容积泵variable geometry wing 可变翼variable load 可变负荷variable mass 变质量variable pitch propeller 可掂螺旋桨variable r esistanc e 可变电阻variable r esistor 可变电阻器variable section 可变断面variable speed drive变速传动variable sweep aircraft 可变翼飞机variable sweep wing 可变翼variable voltage transfor mer 可变电压变压器variable wing air plane 可变翼飞机varianc e 方差varianc e analysis 方差分析varignon's theorem 范力农定理varistor 非线性电阻var nish 漆var nishing 涂漆varying str ess 变应力vaseline 凡士林vector 矢量vector analysis 向量分析vector diagr am 向量图vector field 向量场vector pr oduct 矢量积vee guide v 形导轨vee pulley 三角皮带轮vegetable oil 植物油vehicle 运载工具vehicle hoist 升车机velocimeter 速度计velocity 速度velocity c oefficient 速度系数velocity c urve 速度曲线velocity diagr am 速度图velocity distribution 速度分布velocity gr adient 速度梯度velocity head 速头velocity of blade叶片速度velocity of flow 临velocity of propagation of flame 火焰传播速度velocity of sound 声速velocity pic k up 速度传感器velocity potential 速度势velocity r ange 速度范围velocity r atio 传动比velocity selector 速度选择器velocity stage 速度级velocity triangle速度三角形velox boiler 韦洛克斯锅炉vena c ontr acta 射留缩vending mac hine 自动售货机veneer 单板veneer lathe 剥皮机vent 放气孔vent hole 放气孔vent valve 通气阀vent wire 通气针ventilating fan 通风机ventilation 换气ventilation flue 通风道ventilation installation 通风装置ventilation pipe 通风管ventilation plant 通风装置ventilation system通风系统ventilator 通风机venturi tube 文丘里管venturimeter 文氏管量计ver bal instruction 口头指示verific ation 检验ver nier 游标ver nier bevel protr actor 游标量角器ver nier c aliper 游标卡尺ver nier depth gage 游标深度卡尺ver nier dial 游标刻度盘ver nier engine 游标发动机ver nier gear tooth c aliper 游标齿厚规ver nier gear tooth gage游标齿厚规ver nier height gage高度规ver satile robot 万能机扑ver satility 万能性vertic al axis wind tur bine 竖轴风车vertic al boiler 立式锅炉vertic al broac hing mac hine 立式拉床vertic al compr essor 立式压缩机vertic al conveyor 立式输送机vertic al drilling mac hine立式钻床vertic al electr ochemical for m ing machine 立式电解成形机vertic al engine 立式发动机vertic al feed 垂直进给vertic al feed scr ew 垂直进给丝杠vertic al fin 垂直安定面vertic al forc e 垂直力vertic al gyrosc ope垂直陀螺仪vertic al jounal 枢轴vertic al journal 枢轴颈vertic al lathe 立式车床vertic al m illing head 立铣头vertic al m illing mac hine立式铣床vertic al proj ection 垂直投影vertic al pump 立式泵vertic al shaft 立轴vertic al shaft turbine 立轴式涡轮机vertic al slide 垂直滑板vertic al speed indicator 升降速度表vertic al spindle surfac e grinder 立轴平面磨床vertic al tail 垂直尾翼vertic al tail plane 水平安定面vertic al take off and landing 垂直起落vertic al take off and landing aircraft 垂直起落机vertic al tur bine立轴式涡轮机vertic al tur ning and boring m ill 立式车床vertic al turr et lathe立式转塔车床vertic al water tube boiler 立式水管锅炉vertic al welding 垂直焊very large scale integr ation 超大规模集成电路vessel 船vibr ating c hute 振动式滑槽vibr ating c ompactor 振动压实机vibr ating c onveyor 振动输送机vibr ating feeder 振动式给料机vibr ating mill 振动式磨矿机vibr ating motor 振动歧动机vibr ating plate 振动板vibr ating r eed fr equency meter 振簧式频率计vibr ating scr een 振动筛vibr ating sieve 振动筛vibr ating table 振动台vibr ating tamper 振动夯vibr ating trough 振动槽vibr ation 振动vibr ation absorber 振动阻尼器vibr ation acc eler ation 振动加速度vibr ation amplitude 振动振幅vibr ation analysis 振动分析vibr ation damper 减震器vibr ation damping 减振vibr ation engineering 振动工程vibr ation exc iter 振动发生器振动激励器vibr ation fr equency 频率vibr ation galvanometer 振动式检疗vibr ation gener ator 振动发生器振动激励器vibr ation isolation 振动绝缘vibr ation isolation material 隔振材料vibr ation level 振动级vibr ation mac hine 振动器振动机vibr ation measur ement 振动测定vibr ation meter 振动计vibr ation mode 振动方式vibr ation node 振动节点vibr ation period 振动周期vibr ation pic kup 振动传感器vibr ation pr oof 耐振的vibr ation r ec order 示振器振动显示器vibr ation r esistanc e抗振性vibr ation r oller 振动式碾压机vibr ation spectrum 振动谱vibr ation system 振动系统vibr ation test 振动试验vibr ation tester 振动试验机vibr ation theory 振动理论vibr ator 振动器振子vibr ator motor 振动歧动机vibr atory c entrifuge振荡离心机vibr atory crusher 振动破碎机vibr atory feeder 振动式给料机vibr atory pile driver 振动打桩机vibr atory plate c ompactor 振动板压实机vibr atory tr ansport 振动运输vibr ograph 示振器振动显示器vibr oisolating material 隔振材料vibr ometer 振动计vibr om ill 振动式磨矿机vibr opacker 振动包装机vibr oscope 振动计vice 虎钳vice jaw 虎钳口vice scr ew 虎钳螺杆vicker s hardness 维氏硬度vicker s hardness tester 维氏硬度试验机video monitor 视频监视器video tape r ecor der 磁带录像机view 视图view finder 检影器取景器viewfinder 取景器vinegar 醋vinyl chloride 氯乙烯vinyl r esin 乙烯基尸virial c oefficient 维里系数virtual displac ement 虚位移virtual image 虚象virtual work 虚功visc oelastic body 粘弹体visc oelastic material 粘弹性材料visc oelastic model 粘弹性模型visc oelasticity 粘弹性visc ometer 粘度计visc ometry 粘度测定法visc oplastic material 粘塑性材料visc oplasticity 粘塑性visc osimetry 粘度测定法visc osity 粘性visc osity index 粘度指数visc osity index impr over 改善粘度添加剂visc osity tachometer 粘性转数计visc ous 粘滞的visc ous damper 粘性阻尼器visc ous damping 粘性衰减visc ous drag 粘性阻力visc ous fluid 粘性铃visc ous friction 粘性摩擦visc ous r esistanc e粘性阻力visibility 可贝度visible outline 外形线visible r ays 可见光线vision 视觉visual angle 视角visual chec king 肉眼检查visual exam ination 肉眼检查visual field 视野visual inspection 肉眼检查visual observation 目视观测visual sensor 视觉感受器vitrified bond 陶瓷结合剂vlsi 超大规模集成电路voic e rec ognition 语言识别void 空隙void ratio 空隙率voids 空隙率voigt model 沃伊特模型volatile c omponent 挥发分volatile c onstituent 挥发分volatile matter 挥发物volatile substanc e挥发物volatility 挥发性volatilization 挥发volt 伏特volt amper e c har acteristic 电压电霖性volta's pile 伏打电堆voltage 电压voltage contr ol 电压蝶voltage curr ent char acteristic 电压电霖性voltage divider 分压器voltage dr op 电压降voltage fluctuation 电压波动voltage limiter 电压限制器voltage r ating 额定电压voltage regulation 电压蝶voltage regulator 电压第器voltage stabilizer 电压稳定器稳压器voltaic c ell 伏打电池voltaic pile 伏打电堆voltammeter 电压电量计voltmeter 电压表volume 体积volume c ompressibility 体积压缩率volume elasticity 体积弹性volume flow r ate体积量volume forc e 体积力volume modulus 体积弹性模量volume r atio 容积比volume shrinkage体积收缩volumenometer 容积计volumeter 容积计volumetric efficiency 容积效率;充填系数volumetric expansion 体膨胀volumetric flowmeter 容积量计volute casing 蜗形壳volute housing 蜗形壳volute pump 螺旋泵volute spring 锥形弹簧vortex 涡流旋流vortex burner 涡两喷燃器vortex c hamber 涡良烧室vortex filament 涡吝vortex flow 涡流vortex gener ator 旋涡发生器vortex motion 涡了动vortex pump 涡动泵vortex str eet 涡练vortex tube 涡旋管vorticity 涡旋性vtol 垂直起落vtol aircraft 垂直起落机vtr 磁带录像机vulc anization 硫化vulc anized fiber 刚纸vulc anized rubber 硫化橡胶vulc anizing agent 硫化剂vulc anizing autoclave硫化锅vulc anizing pr ess 平板硫化机w type engine w 形发动机wage 工资wagon 货车wagon balanc e 轨道衡wagon stock 车辆线群wagon tipper 翻车机wake 伴流walking exc avator 步行挖掘机walking mac hine 跨步式机械walking r obot 步行机扑wall 壁wall br ac ket 壁支架wall cr ane 壁装起重机wall drilling mac hine墙装钻床wall jib cr ane 墙座旋臂起重机wall slewing cr ane 墙座旋臂起重机wall soc ket 壁灯灯座wall thic kness 壁厚wankel engine 汪克尔发动机warehouse 仓库warehousing system自动化仓库系统warm ing up 暖机warning 警报warning device 报警装置warning lamp 警报灯warning light 警报灯warning signal 警告信号warp knitting loom 经编机warp knitting mac hine经编机warper整经机warping machine 整经机warping winch 绞缆机washer垫圈washing 洗涤washing machine 洗涤机waste 废物waste disposal 废物处理waste disposer 垃圾粉碎机waste gas 废气waste heat 废热waste heat boiler 废热锅炉waste heat rec overy 废热利用waste iron 废铁waste oil 废油waste pipe 排水管waste r ec overy 废物利用waste steam 废蒸汽waste steam heating 废汽供暖waste utilization 废物利用waste water 废水watch 手表watch glass 表面皿watch oil 钟表油watch spring 表簧water absorbing c apacity 吸水能力water absorption 吸水酌water br ake 水力闸water c alorimeter 水热量计water circulation 水循环water clarific ation 水的净化water c olumn 水柱water c onsumption 水消费量water c ontent 含湿量water c ooled 水冷的water c ooled bearing 水冷轴承water c ooled cylinder 水冷式气缸water c ooled engine水冷发动机water c ooled valve水冷式阀water c ooler 水冷却器water c ooling 水冷却water equivalent 水当量water examination 水质检查water filter 滤水器water gage 水位指示器水位表water gas 水煤气water gas generator 水煤气发生器water glass 水玻璃water hammer 水力冲击water hardening 水淬water head 水头water hose 水龙带water inj ection 喷水water j ac ket 水套water j et 喷射水流喷水water j et pump 喷水泵water j et vac uum pump 水喷真空泵water level 水位water level r egulator 水位第器water line 吃水线water lubric ation 水润滑water meter 水量计water of c ondensation 凝结水water of crystallization 结晶水water paint 水性涂料water per meability 透水性water pipe 供水管water pollution 水污染water power 水能water pr essur e 水压water pr oof test 防水试验water pr oofness 水密性water pump 水泵water purific ation 水净water purifier 净水器water purifying plant 净水装置water quality 水质water quenc hing 水淬water r adiator 水散热器water r am 水冲伙水机water r ate 磨耗率water r esistanc e 抗水性water r esistant paint 防水涂料water r heostat 水变阻器water ring pump 水环泵water seal 水封water separator 脱水器水分离器water sluic e valve制水阀water softening 软水法water softening plant 软水装置water supply 供水water tank 水罐water tap 水龙头water tightness 水密性water tower 贮水塔water tr eatment 水处理water tube 水管water tube boiler 水管式锅炉water vapor 蒸汽water wheel 水轮watering c ar 犬汽车waterpr oof 水密的waterpr oof c anvas 防水布waterpr oof cloth 防水布waterpr oof paint 防水涂料watertight 水密的waterworks 自来水道watt 瓦特watt hour 瓦特小时watt hour meter 积算瓦特计watt meter 电力计watthour meter 累积瓦特计wattless c urrent 无功电流wattless power 无功功率wave 波wave dr ag 波阻wave ener gy 波能wave ener gy air tur bine波能空气透平wave equation 波动方程wave for m波形wave motion 波动wave pr opagation 波的传播wave r esistanc e波阻wave shape 波形wave surfac e 波面wavelength 波长waviness 波纹度wax 蜡wax paper 蜡纸wax patter n 蜡模waxing mac hine 涂蜡机we 旋转腐蚀weak mixtur e 稀混合气weak sand 瘦砂wear 磨耗wear and abrasion resistanc e耐磨性wear c ompensation 磨耗补偿wear lim it 磨损极限wear parts 磨损部件wear proof 耐磨的wear r esistanc e 耐磨性wear r esistant 耐磨的wear r esistant c ast ir on 耐磨铸铁wear test 磨损试验wear testing mac hine磨损试验机wear out parts 磨损部件weather r esistanc e抗气候性weathering 风化weaving 织造weaving mac hine织布机web 梁腹板weber 韦伯wedge 楔wedge brake 楔形闸wedge friction wheel 槽形摩擦轮wedge wire scr een 楔形丝筛wedm电火花线切割weeder 除草器weibull distribution 韦布尔分布weigh bar shaft 回动轴weigh shaft 回动轴weighing 秤量weighing machine 秤weight 法码weight distribution 重量分布weight per br ake horsepower 每马力重量weight per unit power 单位功率重量weight r atio 重量比weight r eduction 减轻重量weighted accumulator 重锤式蓄能器weighting function 加权函数weightless state失重状态weightlessness 无重力weights and measures 度量衡weir 溢吝weld 焊接weld bead 焊道weld cr ac k焊接裂缝weld metal 熔敷金属weld penetr ation 溶透weld pool 熔池weldability 可焊性weldability test 可焊性试验welded c onstr uction 焊接结构welded j oint 焊接连接welded pipe 焊管welded pipe line焊接管道welded tube 焊管welder 焊工welding 焊接welding apparatus 焊接机welding blowpipe气焊枪welding c able 电焊引线welding c urrent 焊接电流welding defect 焊接缺陷welding dinamo 电焊发电机welding distortion 焊接变形welding electr ode焊条welding equipment 焊接设备welding flame 焊接焰welding flux 焊药welding generator 电焊发电机welding gloves 焊工手套welding goggles 焊工护目镜welding head 焊头welding heat 焊接热welding helmet 焊工帽welding leads 电焊引线welding mac hine 焊接机welding oper ator 焊工welding powder 焊药welding proc ess 焊接法welding r obot 焊接机扑welding r od 电焊条welding sequenc e焊接程序welding shop 焊接车间welding str ess 焊接应力welding torch 气焊枪welding tr ansfor mer 焊接变压器weldless tube 无缝管well pump 井泵wet air 湿空气wet air pump 湿气泵wet and dry bulb ther mometer 干湿球湿度计wet bulb ther mometer 湿球温度表wet classifier 湿式分级机wet cleaner 湿式滤清器湿法清洗器wet grinding 湿磨法;湿式粉碎wet grinding m ill 湿磨机wet metallurgy 湿法冶金wet pr ecipitator 湿式收尘器湿式除尘器wet pr oc ess 湿法wet purification 湿法净化wet purifier 湿式滤清器湿法清洗器wet separ ator 湿式选矿机wet steam 湿蒸汽wetness 湿度wettability 湿润性wetted perimeter 湿润周wetted surfac e 浸湿面wetting 润湿whale factory ship 捕鲸加工船whale oil 鲸油whaleboat 捕鲸船wharf cr ane 码头起重机wheatstone bridge惠斯登电桥wheel 轮wheel and axle 轮轴wheel axle 轮轴wheel balanc er 车轮平衡试验机wheel base 轴距wheel br ake 轮闸wheel br aking cylinder 制动轮缸wheel c amber 前轮外倾角wheel c entr e 轮心wheel cr ane 轮胎起重机wheel cylinder 制动轮缸wheel disk 辐板wheel dr esser 砂轮修整装置wheel exc avator 轮式挖土机wheel flange 轮缘wheel grinding machine 车轮磨床wheel guard 砂轮罩wheel head 磨头wheel hub 轮毂wheel lathe 车轮车床wheel loader 轮式装载机wheel mounted cr ane 轮胎起重机wheel pr ess 轮压机wheel rim 轮箍wheel set 轮轴wheel slip 车轮滑转wheel spindle 轮轴wheel spindle stoc k磨头wheel spoke 轮辐wheel tr ac k轮距wheel tr ead 胎面wheel type tr actor 轮式拖拉机wheelbarrow 手推车wheeled tr actor 轮式拖拉机wheelhead 磨头whetstone 磨刀石whirl 涡流旋流whirl etc hing 旋转腐蚀whisker 金属须white heart malleable cast ir on 白心可锻铸铁white heat 白热white iron 白铸铁white metal 白合金white noise 白色噪声whitworth scr ew thr ead 惠氏螺纹whitworth thr ead 惠氏螺纹whole depth 齿全高whole number 整数wick lubric ation 油绳润滑wick lubric ator 灯心注油器油绳润滑器wick oiler 灯心注油器油绳润滑器widia 碳化钨硬质合金width 宽wien's displac ement law 维痘移定律winch 卷扬机wind box 风箱wind dir ection indic ator 风向指示器wind driven electric plant 风能动力装置wind energy 风能wind load 风荷重wind motor 风力发动机wind power plant 风力发电站wind power station 风力发电站wind pr essur e 风压wind r esistanc e 风阻力wind tunnel 风洞wind tunnel balanc e 风洞天平wind tunnel test 风洞试验winding 线圈;绕线winding dr um 卷筒winding machine 绕线机windlass 起锚绞盘windm ill 风车windrower 割晒机windshield 风挡windshield heater 除霜器windshield wiper 挡风玻璃刮水器wing 翼wing ar ea 机翼面积wing chor d 翼弦wing loading 机翼单位面积负荷wing profile 翼剖面wing pump 叶轮泵wing screw 蝶形螺钉wing section 翼截面wing span 翼展wing spar 横梁winged nut 翼螺帽winged screw 翼形螺钉winkler gas gener ator 文克勒煤气发生炉winkler gas pr oduc er 文克勒煤气发生炉wire 金属丝wire ar mor ed hose钢丝包皮软管wire brush 钢丝刷wire brushing 用钢丝刷清理wire cloth 筛网布wire cut edm 电火花线切割wire cut electro disc harge mac hine电火花线切割机wire cutting 电火花线切割wire cutting off mac hine 钢丝切断机wire dr awing 拉线wire dr awing benc h 拔丝机wire dr awing mac hine 拔丝机wire electrode 电极丝wire gage 线规wire gaze 金属丝网wire glass 络网玻璃wire m ill 线材轧机wire nail 销钉wire raising mac hine钢丝起绒机wire rod 线材wire rope 钢丝绳wire saw 钢丝锯wire scr een 金属丝网筛wire sieve 金属丝网筛wire spoke 钢丝轮辐wire stitc her 网器wire stitc hing mac hine网器wire str aightener 钢丝校正机wire str ain gage电阻丝应变仪wire weaving mac hine 金属线网织机wire wheel 钢丝辐轮wired glass 铁丝玻璃wireless c ompass 无线电罗盘wiring 配线wiring diagram 布线图wolframic acid 钨酸wood boring machine 木工钻床wood drilling mac hine 木工钻床wood fibr e 木质纤维wood file 木锉刀wood lathe 木工车床wood meal 木粉wood m illing mac hine木工铣床wood pattern 木模wood pattern maker 木模工wood pattern shop 制模车间wood pipe 木管wood planer 木刨床wood powder 木粉wood pulp grinder 木浆研磨机wood screw 木螺丝wood tar 木焦油wood working 木材加工wood working machine 木工机床wood working tool 木工工具wood's alloy 伍德合金wood's metal 伍德合金wooden 木制的wooden belt pulley 木皮带轮wooden hammer 木锤wooden pipe 木管wooden pole 木桩wooden ship 木船wooden tube 木管wooden vessel 木船woodr uff key 半圆键woodwor k 木制品woodwor king 木材加工woodwor king mac hine木工机床wool felt 毛毡wool spinning machine 毛纺机wool washing mac hine 洗毛机work 功work bench 工专work cycle 工总期work hardening 加工硬化work table 工专workability 可加工性workhead 工罪架working clear anc e工卒隙working conditions 工柞件working cylinder 工鬃working dr awing 工准working fluid 工族working gage 工卓规working load 工缀载working medium工组质working position 工谆置working pr essure 工坠力working principle 工篆理working station 工拙working stress 工爪力working stroke 工仔程working temper atur e 工茁度workpiece 工件workpiece headstoc k 工罪架works 厂workshop 车间workshop tr uc k修理车worm蜗杆worm c onveyor 螺旋输送器worm drive 蜗轮传动worm gear 蜗轮worm gear hob 蜗轮滚刀worm gear hobbing machine 蜗轮滚齿机worm gearing 蜗杆传动装置worm gear s 蜗杆传动装置worm grinder 蜗杆磨床worm milling mac hine 蜗杆铣床worm r educ er 蜗轮减速机worm shaft 蜗轴worm wheel 蜗轮worm wheel hobbing mac hine 蜗轮滚齿机wound r otor 绕线型转子wound r otor induction motor 绕线式电动机wound r otor type motor 绕线式电动机woven belt 帆布皮带wrapper 包装机wrapping angle 接触角wrapping mac hine包装机wrapping paper 包装纸wreck crane 救援起重机wrecker truc k 救险汽车wrench 扳手wrench j aws 板手钳口wrist pin 活塞销wrong oper ation 误动作wrought alloy 变形合金wrought aluminium alloy 变形铝合金wrought ir on 熟铁wrought steel 锻钢;熟钢x cross member x 形横梁x engine x形发动机x gear 修整齿轮x ray analysis x 射线分析x ray appar atus x 射线装置x ray defectoscopy x 射线检查x ray m icr oscope x 射线显微镜x ray photogr aph x 射线照片x ray spectr ometer x射线分光计x ray testing x 射线检查x rays x 射线x shaped x形的x shaped cr oss member x 形横梁x type x形的x type engine x 型发动机x y plotter x y 绘图机x zer o gear 零变位齿轮xenon 氙xenon lamp 氙灯xylene 二甲苯xylol 二甲苯y connection 星形连接y piece 分叉管y pipe 分叉管y type engine y 形发动机yac ht 快艇yag crystal 钇铝石榴石晶体yag laser 激光器yar d 编组站yarn 纱yarn twisting mac hine 捻丝机yarrow boiler 雅鲁式锅炉yaw angle 偏航角yawing 偏航yawing moment 偏航力矩yawmeter 偏航计yellow phosphor us 黄磷yield 收获率yield point 屈服点yield stress 屈服应力yoke 轭铁yoke end u 形夹yoked c onnecting r od 叉式连杆young's modulus 弹性模数yttrium alum inium gar net crystal 钇铝石榴石晶体yttrium alum inium gar net laser 激光器z axis z 轴z bar z 字钢z steel z 字钢zeolite 沸石zero adjustment 零点蝶zero gravity 无重力zero gravity state 失重状态zero point 零点zero point energy 零点能zero potential 零电位zero power reactor 零功率反应堆zero r etur n 原点归复zero setting 零位蝶zerol bevel gear 零度弧齿伞齿轮zigzag 之字形zigzag antenna 曲折天线zigzag riveting 交错铆接zinc 锌zinc alloy 锌合金zinc base alloy 锌基合金zinc bronze 锌青铜zincing 镀锌zipper 拉锁zircon 锆石zirconium 锆zone of combustion 燃烧带zone of preheating 预热区。
机器翻译的基本原理和方法摘要:机器翻译是一种通过计算机自动将一种语言的表达转换为另一种语言的方法。
本文将介绍,包括传统方法和最新的深度学习方法。
第一部分:引言机器翻译是人工智能领域的一个重要研究方向,旨在通过计算机自动将一种语言的表达转换为另一种语言,以实现不同语言之间的交流和理解。
机器翻译的研究和应用对于促进全球信息交流和跨文化交流具有重要意义。
本文将介绍,包括传统方法和最新的深度学习方法。
第二部分:传统机器翻译方法传统机器翻译方法主要基于规则的方法和统计的方法。
规则的方法是通过定义一个包含语法、语义等方面知识的规则库,在翻译过程中根据这些规则来实现翻译。
规则的方法需要人工编写规则,因此需要大量的人力和时间,并且对于语言的规则和特点的覆盖较为有限,因此在实际应用中并不常见。
统计的方法是通过大规模语料库的统计分析来实现翻译。
统计的方法通常包括两个主要步骤:训练和解码。
在训练过程中,计算机通过学习大规模的双语语料库,建立一个统计模型,用于表示两种语言之间的对应关系。
在解码过程中,计算机根据给定的输入语句,通过搜索找到最有可能的输出语句。
统计的方法在实际应用中取得了很好的效果,但是由于其依赖大规模的语料库,对于语言的覆盖和处理能力有一定的限制。
第三部分:最新的深度学习方法最新的深度学习方法在机器翻译领域取得了重大突破。
深度学习是一种基于神经网络的机器学习方法,通过多层次的特征表示和学习来实现对复杂模式的建模。
深度学习方法主要包括递归神经网络(RNN)和卷积神经网络(CNN)两种。
递归神经网络是一种能够处理序列数据的神经网络模型,在机器翻译中被广泛应用。
递归神经网络通过对输入语句的逐个词进行处理,并通过词与词之间的关系来预测输出语句。
递归神经网络能够捕捉到语言的上下文信息,因此在翻译长句子和复杂句子时具有一定的优势。
卷积神经网络是一种能够提取局部特征和整体特征的神经网络模型,在机器翻译中也有一定的应用。
机器翻译研究综述随着全球化的加速和信息技术的普及,机器翻译技术已经成为跨语言交流的重要工具。
本文将综述机器翻译的研究现状、应用实践、研究方法以及未来发展的趋势和挑战。
机器翻译的基本概念和发展历程机器翻译是指利用计算机技术将一种自然语言转换为另一种自然语言的过程。
从20世纪50年代初期的基于规则的方法,到90年代初期的统计学习方法,再到如今的深度学习技术,机器翻译在短短几十年间取得了长足的进步。
机器翻译的研究现状目前的机器翻译研究主要集中在基于深度学习的神经网络翻译模型。
其中,循环神经网络(RNN)、长短期记忆网络(LSTM)和变压器(Transformer)模型是近年来最为常用的方法。
随着技术的不断发展,端到端(E2E)翻译模型也逐渐成为研究热点。
此外,研究者们还不断探索如何将语法分析、语义理解和机器翻译相结合,以提高翻译的质量。
机器翻译的应用实践机器翻译已经广泛应用于各个领域。
例如,谷歌翻译、百度翻译、有道翻译等商业翻译工具为全球用户提供了即时、高效的翻译服务。
此外,机器翻译也在医疗、金融、法律等专业领域得到了广泛应用。
然而,目前机器翻译仍存在一些问题,如对于复杂句型和特定领域的专业术语处理能力较弱,这需要进一步加强针对性的训练和学习。
机器翻译的研究方法目前,机器翻译的研究方法主要分为传统机器学习和深度学习两大类。
传统机器学习主要包括基于规则、基于统计和基于实例的方法。
而深度学习则利用神经网络模型进行端到端的翻译,其中循环神经网络、长短期记忆网络和变压器模型是最为常用的。
随着技术的不断发展,混合方法(如结合深度学习和传统机器学习的优点)也逐渐成为研究热点。
结论机器翻译研究在过去的几十年里取得了显著的进展,尤其在深度学习技术的应用方面取得了突破性成果。
然而,仍存在许多挑战和问题需要进一步研究和解决,如提高翻译的准确性、处理复杂句型和特定领域的专业术语等。
未来的研究可以以下几个方面:1、探索更为有效的模型结构和训练方法以提高翻译质量。
Metal Cutting and LatheMetal CuttingThe importance of machining processes can be emphasised by the fact that every product we use in our daily life has undergone this process either directly or indirectly.(1) In USA, more than $100 billions are spent annually on machining and related operations.(2) A large majority (above 80%) of all the machine tools used in the manufacturing industry have undergone metal cutting.(3) An estimate showed that about 10 to 15% of all the metal produced in USA was converted into chips.。
These facts show the importance of metal cutting in general manufacturing. It is therefore important to understand the metal cutting process in order to make the best use of it.A number of attempts have been made in understanding the metal cutting process and using this knowledge to help improve manufacturing operations which involved metal cutting.typical cutting tool in simplified form is shown in Fig.7.1. The important features to be observed are follows.1. Rake angle. It is the angle between the face of the tool called the rake face and the normal to the machining direction. Higher the rake angle, better is the cutting and less are the cutting forces, increasing the rake angle reduces the metal backup available at the tool rake face.This reduces the strength of the tool tip as well as the heat dissipation through the tool. Thus, there is a maximum limit to the rake angle and this is generally of the order of 15°for high speed steel tools cutting mild steel. It is possible to have rake angles at zero or negative.2. Clearance angle. This is the angle between the machined surface and the underside of the tool called the flank face. The clearance angle is provided such that the tool will not rub the machined surface thus spoiling the surface and increasing the cutting forces. A very large clearance angle reduces the strength of the tool tip, and hence normally an angle of the order of 5~6°is used.The conditions which have an important influence on metal cutting are work material, cutting tool material, cutting tool geometry, cutting speed, feed rate, depth of cut and cutting fluid used.The cutting speed, v, is the speed with which the cutting tool moves through the work material. This is generally expressed in metres per second (ms-1).Feed rate, f, may be defined as the small relative movement per cycle (per revolution or per stroke) of the cutting tool in a direction usually normal to the cutting speed direction.Depth of cut, d, is the normal distance between the unmachined surface and the machined surface.Chip FormationMetal cutting process is a very complex process. Fig.7.2 shows the basic material removal operation schematically.The metal in front of the tool rake face gets immediately compressed, first elastically and then plastically. This zone is traditionally called shear zone in view of fact that the material in the final form would be removed by shear from the parent metal.The actual separation of the metal starts as a yielding or fracture, depending upon the cutting conditions, starting from the cutting tool tip. Then the deformed metal (called chip) flows over the tool (rake) face.If the friction between the tool rake face and the underside of the chip (deformed material) is considerable, then the chip gets further deformed, which is termed as secondary deformation. The chip after sliding over the tool rake face is lifted away from the tool, and the resultant curvature of the chip is termed as chip curl.Plastic deformation can be caused by yielding, in which case strained layers of material would get displaced over other layers along the slip-planes which coincide with the direction of maximum shear stress.A chip is variable both in size and shape in actual manufacturing practice. Study of chips is one of the most important things in metal cutting. As would be seen later, the mechanics of metal cutting are greatly dependent on the shape and size of the chips produced.Chip formation in metal cutting could be broadly categorised into three types: (Fig.7.3)(1) Discontinuous chip(2) Continuous chip(3) Continuous chip with BUE (Built up edge)Discontinuous Chip.The segmented chip separates into short pieces, which may or may not adhere to each other. Severe distortion of the metal occurs adjacent to the face, resulting in a crack that runs ahead of the tool.Eventually, the shear stress across the chip becomes equal to the shear strength of the material, resulting in fracture and separation. With this type of chip, there is little relative movement of the chip along the tool face, Fig.7.3a.Continuous chip. The continuous chip is characterized by a general flow of the separated metal along the tool face. There may be some cracking of the chip, but in this case it usually does not extend far enough to cause fracture.This chip is formed at the higher cutting speeds when machining ductile materials. There is little tendency for the material to adhere to the tool. The continuous chip usually shows a good cutting ratio and tends to produce the optimum surface finish, but it may become an operating hazard, Fig.7.3b.Continuous with a built-up edge.This chip shows the existence of a localized, highly deformed zone of material attached or “welded” on the to ol face.Actually, analysis of photomicrographs shows that this built-up edge is held in place by the static friction force until it becomes so large that the external forces acting on it cause it to dislodge, with some of it remaining on the machined surface and the rest passing off on the back side of the chip, Fig.7.3c.•Shear ZoneThere are basically two schools of thought in the analysis of the metal removal process. One school of thought is that the deformation zone is very thin and planar as shown in Fig.7.4a. The other school thinks that the actual deformation zone is a thick one with a fan shape as shown in Fig.7.4b.Though the first model (Fig.7.4a) is convenient from the point of analysis, physically it is impossible to exist. This is because for the transition from undeformed material to deform to take place along a thin plane, the acceleration across the plane has to be infinity.Similarly the stress gradient across the shear plane has to be very large to be practical.In the second model (Fig.7.4b) by making the shear zone over a region, the transitions in velocities and shear stresses could be realistically accounted for.The angle made by the shear plane with the cutting speed vector, Φis a veryimportant parameter in metal cutting. Higher the shear angle better is the cutting performance. From a view of the Fig.7.4a, it can be observed that a higher rake angles give rise to higher shear angles.Cutting Tool MaterialsVarious cutting tool materials have been used in the industry for different applications. A number of developments have occurred in the current century.A large variety of cutting tool materials has been developed to cater to the variety of materials used in these programmes. Before we discuss the properties of these materials, let us look at the important characteristics expected of a cutting tool material.1. Higher hardness than that of the workpiece material being machined, so that it can penetrate into the work material.2. Hot hardness, which is the ability of the material to retain its hardness at elevated temperatures in view of the high temperatures existing in the cutting zone.3. Wear resistance—The chip-tool and chip-work interfaces are exposed to such severe conditions that adhesive and abrasion wear is very common. The cutting tool material should therefore have high abrasion resistance to improve the effective life of the tool.4. Toughness—Even though the tool is hard, it should have enough toughness to withstand the impact loads that come in the beginning of cut or force fluctuations due to imperfections in the work material. This requirement is going to be more useful for the interrupted cutting, e.g. milling.5. Low friction—The coefficient of friction between the chip and tool should be low. This would allow for lower wear rates and better chip flow.6. Thermal characteristics—Since a lot of heat is generated at the cutting zone, the tool material should have higher thermal conductivity to dissipate this heat in the shortest time, otherwise the tool temperature would become high, reducing its life.All these characteristics may not be found in a single tool material. Improved tool materials have been giving a better cutting performance.Surface FinishMachining operations are utilized in view of the better surface finish that could be achieved by it compared to other manufacturing operations.Thus it is important to know what would be the effective surface finish that can be achieved in a machining operation. The surface finish in a given machining operation is a result of two factors:(1) the ideal surface finish, which is a result of the geometry of the manufacturing process which can be determined by considering the geometry of the machining operation, and(2) the natural component, which is a result of a number of uncontrollable factors in machining, which is difficult to predict.Ideal Surface Finish in TurningThe actual turning tool used would have a nose radius in place of the sharp tool point, which modifies the surface geometry as shown in Fig.7.5a. If the feed rate is very small, as is normal in finish turning, the surface is produced purely by the nose radius alone as shown in Fig.7.5.For the case in Fig.7.5, the surface roughness value is to beR a=8f2/(18R√3)Where: R a is the surface roughness valueR is the nose radiusf is the feed rateThe above are essentially geometric factors and the values represent an ideal situation. The actual surface finish obtained depends to a great extent upon a number offactors such as:(1) the cutting process parameter, speed, feed and depth of cut(2) the geometry of the cutting tool(3) application of cutting fluid(4) work and tool material characteristics(5) rigidity of the machine tool and the consequent vibrations.The major influence on surface finish is exerted by the feed rate and cutting speed. As the feed decreases, from the above equations, we can see that the roughness index decreases.Similarly as the cutting speed increases, we have better surface finish. Thus while making a choice of cutting process parameters for finish, it is desirable to have high cutting speed and small feed rates.•Cutting FluidsThe functions of cutting fluids (which are often erroneously called coolants) are: •To cool the tool and workpiece•To reduce the frictionTo protect the work against rusting•To improve the surface finish•To prevent the formation of built-up edge•To wash away the chips from the cutting zoneHowever, the prime function of a cutting fluid in a metal cutting operation is to control the total heat. This can be done by dissipating the heat generated as well as reducing it. The mechanisms by which a cutting fluid performs these functions are: cooling action and lubricating action.Cooling action.Originally it was assumed that cutting fluid improves the cutting performance by its cooling properties alone. That is why the name coolant was given to it.Since most of the tool wear mechanisms are thermally activated, cooling the chip tool interface helps in retaining the original properties of the tool and hence prolongs its life. However, a reduction in the temperature of the workpiece may under certain conditions increase the shear flow stress of the workpiece, thereby decreasing tool life. It has been shown through a number of investigations that cooling in fact is one of the major factors in improving the cutting performance.Lubricating action.The best improvement in cutting performance can be achieved by the lubricating action since this reduces the heat generated, thus reducing the energy input to the metal cutting operation.However, if the cutting fluid is to be effective, it must reach the chip tool interface. But it is not easy to visualize how it is accomplished in the case of a continuous turning with a single point turning tool, specially when the chip-tool contact pressure is as high as 70 MPa. Merchant thought that minute asperities existed at the chip-tool interface and the fluid was drawn into the interface by the capillary action of the interlocking network of these surface asperities.Lathe and Turning•The Lathe and Its ConstructionA lathe is a machine tool used primarily for producing surfaces of revolution andflat edges.Based on their purpose, construction, number of tools that can simultaneously be mounted, and degree of automation, lathes-or, more accurately, lathe-type machine tools can be classified as follows:(1)Engine lathes(2)Toolroom lathes(3)Turret lathes(4)Vertical turning and boring mills(5)Automatic lathes(6)Special-purpose lathesIn spite of that diversity of lathe-type machine tools, they all have common features with respect to construction and principle of operation. These features can best be illustrated by considering the commonly used representative type, the engine lathe. Following is a description of each of the main elements of an engine lathe, which is shown in Fig.11.1.Lathe bed. The lathe bed is the main frame, involving a horizontal beam on two vertical supports. It is usually made of grey or nodular cast iron to damp vibrations and is made by casting.It has guideways to allow the carriage to slide easily lengthwise. The height of the lathe bed should be appropriate to enable the technician to do his or her job easily and comfortably.Headstock. The headstock is fixed at the left hand side of the lathe bed and includes the spindle whose axis is parallel to the guideways (the slide surface of the bed). The spindle is driven through the gearbox, which is housed within the headstock.The function of the gearbox is to provide a number of different spindle speeds (usually 6 up to 18 speeds). Some modern lathes have headstocks with infinitely variable spindle speeds, which employ frictional ,electrical ,or hydraulic drives.The spindle is always hollow, i. e., it has a through hole extending lengthwise. Bar stocks can be fed through that hole if continuous production is adopted.Also, that hole has a tapered surface to allow mounting a plain lathe center. The outer surface of the spindle is threaded to allow mounting of a chuck, a face plate, or the like.Tailstock.The tailstock assembly consists basically of three parts, its lower base, an intermediate part, and the quill. The lower base is a casting that can slide on the lathe bed along the guideways, and it has a clamping device to enable locking the entire tailstock at any desired location, depending upon the length of the workpiece.The intermediate part is a casting that can be moved transversely to enable alignment of the axis of the tailstock with that of the headstock. The third part, the quill, is a hardened steel tube, which can be moved longitudinally in and out of the intermediate part as required.This is achieved through the use of a handwheel and a screw, around which a nut fixed to the quill is engaged. The hole in the open side of the quill is tapered to enable mounting of lathe centers or other tools like twist drills or boring bars. The quill can be locked at any point along its travel path by means of a clamping device.The carriage.The main function of the carriage is mounting of the cutting tools and generating longitudinal and/or cross feeds. It is actually an H-shaped block that slides on the lathe bed between the headstock and tailstock while being guided by the V-shaped guideways of the bed.The carriage can be moved either manually or mechanically by means of the apron and either the feed rod or the lead screw.When cutting screw threads, power is provided to the gearbox of the apron by the lead screw. In all other turning operations, it is the feed rod that drives the carriage. The lead screw goes through a pair of half nuts, which are fixed to the rear of the apron.When actuating a certain lever, the half nuts are clamped together and engage with the rotating lead screw as a single nut, which is fed, together with the carriage, along the bed. When the lever is disengaged, the half nuts are released and the carriage stops.On the other hand, when the feed rod is used, it supplies power to the apron through a wormgear. The latter is keyed to the feed rod and travels with the apron along the feed rod, which has a keyway extending to cover its whole length.A modern lathe usually has a quick-change gearbox located under the headstock and driven from the spindle through a train of gears. It is connected to both the feed rod and the lead screw and enables selecting a variety of feeds easily and rapidly by simply shifting the appropriate levers. The quick-change gearbox is employed in plain turning, facing and thread cutting operations. Since that gearbox is linked to the spindle, the distance that the apron (and the cuttingtool) travels for each revolution of the spindle can be controlled and is referred to as the feed.。