机械专业英语论文3000字怎么写
A machine tool is a powered mechanical device， typically used to fabricate metal components of machines by machining， which is the selective removal of The term machine tool is usually reserved for tools that used a power source other than human movement， but they can be powered by people if appropriately set Many historians of technology consider that the true machine tools were born when direct human involvement was removed from the shaping or stamping process of the different kinds of The earliest lathe with direct mechanical control of the cutting tool was a screw-cutting lathe dating to about [1] This lathe "produced screw threads out of wood and employed a true compound slide rest"The first machine tools offered for sale ( commercially available) were constructed by one Matthew Murray in England around [2]Contents [hide]1 Overview 2 Examples 3 See also 4 References 5 Bibliography 6 Further reading 7 External links [edit] OverviewMachine tools can be powered from a variety of Human and animal power are options， as is energy captured through the use of However， modern machine tools began to develop only after the development of the steam engine， which led to the Industrial R Today， most machine tools are powered by Machine tools can be operated manually， or under automatic Early machines used flywheels to stabilize their motion and had complex systems of gears and levers to control the machine and the piece being worked Soon after World War II， the numerical control (NC) machine was NC machines used a series of numbers punched on paper tape or punch cards to control their In the 1960s， computers were added to give even more flexibility to the Such machines became known as computerized numerical control (CNC) NC and CNC machines could precisely repeat sequences over and over， and could produce much more complex pieces than even the most skilled tool Before long， the machines could automatically change the specific cutting and shaping tools that were being For example， a drill machine might contain a magazine with a variety of drill bits for producing holes of various Previously， either machine operators would usually have to manually change the bit or move the work piece to another station to perform these different The next logical step was to combine several different machine tools together， all under computer These are known as machining centers， and have dramatically changed the way parts are From the simplest to the most complex， most machine tools are capable of at least partial self-replication， and produce machine parts as their primary [edit] ExamplesExamples of machine tools are:Broaching machine Drill press Gear shaper Hobbing machine Hone Lathe Screw machines Milling machine Shaper Saws Planer Stewart platform mills Grinding machines When fabricating or shaping parts， several techniques are used to remove unwanted Among these are:Electrical discharge machining Grinding (abrasive cutting) Multiple edge cutting tools Single edge cutting tools Other techniques are used to add desired Devices that fabricate components by selective addition of material are called rapid prototyping Several regions of the United States became centers for machine tool development between 1800 and 1950， including Philadelphia， Pennsylvania; Cincinnati， Ohio; Rockford， Illinois; Providence， Rhode Island] Springfield， Vermont; Windsor， Vermont; Hartford， Connecticut; and Bridgeport， C 给你
原文：9 MACHINABILITYThe machinability of a material usually defined in terms of four factors:1、$ l m I `5 L* eSurface finish and integrity of the machined part;2、; u: I% F/ b$ t( O" ?' I2 MTool life obtained;3、1 F }: a% W1 W5 R l7 @* q; jForce and power requirements;4、 p) @0 }5 c* S+ I: IChip Thus， good machinability good surface finish and integrity， long tool life， and low force And power As for chip control， long and thin (stringy) cured chips， if not broken up， can severely interfere with the cutting operation by becoming entangled in the cutting Because of the complex nature of cutting operations， it is difficult to establish relationships that quantitatively define the machinability of a In manufacturing plants， tool life and surface roughness are generally considered to be the most important factors in Although not used much any more， approximate machinability ratings are available in the example 1 Machinability Of Steels6 }" `- x) E* V* T+ DBecause steels are among the most important engineering materials (as noted in Chapter 5)， their machinability has been studied The machinability of steels has been mainly improved by adding lead and sulfur to obtain so-called free-machining Resulfurized and Rephosphorized ， m# n- K R; @Sulfur in steels forms manganese sulfide inclusions (second-phase particles)， which act as stress raisers in the primary shear As a result， the chips produced break up easily and are small; this improves The size， shape， distribution， and concentration of these inclusions significantly influence Elements such as tellurium and selenium， which are both chemically similar to sulfur， act as inclusion modifiers in resulfurized Phosphorus in steels has two major It strengthens the ferrite， causing increased Harder steels result in better chip formation and surface Note that soft steels can be difficult to machine， with built-up edge formation and poor surface The second effect is that increased hardness causes the formation of short chips instead of continuous stringy ones， thereby improving Leaded S A high percentage of lead in steels solidifies at the tip of manganese sulfide In non-resulfurized grades of steel， lead takes the form of dispersed fine Lead is insoluble in iron， copper， and aluminum and their Because of its low shear strength， therefore， lead acts as a solid lubricant (Section 11) and is smeared over the tool-chip interface during This behavior has been verified by the presence of high concentrations of lead on the tool-side face of chips when machining leaded When the temperature is sufficiently high-for instance， at high cutting speeds and feeds (Section 6)—the lead melts directly in front of the tool， acting as a liquid In addition to this effect， lead lowers the shear stress in the primary shear zone， reducing cutting forces and power Lead can be used in every grade of steel， such as 10xx， 11xx， 12xx， 41xx， Leaded steels are identified by the letter L between the second and third numerals (for example， 10L45) (Note that in stainless steels， similar use of the letter L means “low carbon，” a condition that improves their corrosion )However， because lead is a well-known toxin and a pollutant， there are serious environmental concerns about its use in steels (estimated at 4500 tons of lead consumption every year in the production of steels) Consequently， there is a continuing trend toward eliminating the use of lead in steels (lead-free steels) Bismuth and tin are now being investigated as possible substitutes for lead in Calcium-Deoxidized S An important development is calcium-deoxidized steels， in which oxide flakes of calcium silicates (CaSo) are These flakes， in turn， reduce the strength of the secondary shear zone， decreasing tool-chip interface and Temperature is correspondingly Consequently， these steels produce less crater wear， especially at high cutting Stainless S Austenitic (300 series) steels are generally difficult to Chatter can be s problem， necessitating machine tools with high However， ferritic stainless steels (also 300 series) have good Martensitic (400 series) steels are abrasive， tend to form a built-up edge， and require tool materials with high hot hardness and crater-wear Precipitation-hardening stainless steels are strong and abrasive， requiring hard and abrasion-resistant tool The Effects of Other Elements in Steels on M The presence of aluminum and silicon in steels is always harmful because these elements combine with oxygen to form aluminum oxide and silicates， which are hard and These compounds increase tool wear and reduce It is essential to produce and use clean Carbon and manganese have various effects on the machinability of steels， depending on their Plain low-carbon steels (less than 15% C) can produce poor surface finish by forming a built-up Cast steels are more abrasive， although their machinability is similar to that of wrought Tool and die steels are very difficult to machine and usually require annealing prior to Machinability of most steels is improved by cold working， which hardens the material and reduces the tendency for built-up edge Other alloying elements， such as nickel， chromium， molybdenum， and vanadium， which improve the properties of steels， generally reduce The effect of boron is Gaseous elements such as hydrogen and nitrogen can have particularly detrimental effects on the properties of Oxygen has been shown to have a strong effect on the aspect ratio of the manganese sulfide inclusions; the higher the oxygen content， the lower the aspect ratio and the higher the In selecting various elements to improve machinability， we should consider the possible detrimental effects of these elements on the properties and strength of the machined part in At elevated temperatures， for example， lead causes embrittlement of steels (liquid-metal embrittlement， hot shortness; see Section 3)， although at room temperature it has no effect on mechanical Sulfur can severely reduce the hot workability of steels， because of the formation of iron sulfide， unless sufficient manganese is present to prevent such At room temperature， the mechanical properties of resulfurized steels depend on the orientation of the deformed manganese sulfide inclusions (anisotropy) Rephosphorized steels are significantly less ductile， and are produced solely to improve 2 Machinability of Various Other MetalsAluminum is generally very easy to machine， although the softer grades tend to form a built-up edge， resulting in poor surface High cutting speeds， high rake angles， and high relief angles are Wrought aluminum alloys with high silicon content and cast aluminum alloys may be abrasive; they require harder tool Dimensional tolerance control may be a problem in machining aluminum， since it has a high thermal coefficient of expansion and a relatively low elastic Beryllium is similar to cast Because it is more abrasive and toxic， though， it requires machining in a controlled Cast gray irons are generally machinable but Free carbides in castings reduce their machinability and cause tool chipping or fracture， necessitating tools with high Nodular and malleable irons are machinable with hard tool Cobalt-based alloys are abrasive and highly work- They require sharp， abrasion-resistant tool materials and low feeds and Wrought copper can be difficult to machine because of built-up edge formation， although cast copper alloys are easy to Brasses are easy to machine， especially with the addition pf lead (leaded free-machining brass) Bronzes are more difficult to machine than Magnesium is very easy to machine， with good surface finish and prolonged tool However care should be exercised because of its high rate of oxidation and the danger of fire (the element is pyrophoric)Molybdenum is ductile and work-hardening， so it can produce poor surface Sharp tools are Nickel-based alloys are work-hardening， abrasive， and strong at high Their machinability is similar to that of stainless Tantalum is very work-hardening， ductile， and It produces a poor surface finish; tool wear is Titanium and its alloys have poor thermal conductivity (indeed， the lowest of all metals)， causing significant temperature rise and built-up edge; they can be difficult to Tungsten is brittle， strong， and very abrasive， so its machinability is low， although it greatly improves at elevated Zirconium has good It requires a coolant-type cutting fluid， however， because of the explosion and 3 Machinability of Various Materials; n+ {0 C# N' t: K& D5 Y7 nGraphite is abrasive; it requires hard， abrasion-resistant， sharp Thermoplastics generally have low thermal conductivity， low elastic modulus， and low softening Consequently， machining them requires tools with positive rake angles (to reduce cutting forces)， large relief angles， small depths of cut and feed， relatively high speeds， andproper support of the Tools should be External cooling of the cutting zone may be necessary to keep the chips from becoming “gummy” and sticking to the Cooling can usually be achieved with a jet of air， vapor mist， or water-soluble Residual stresses may develop during To relieve these stresses， machined parts can be annealed for a period of time at temperatures ranging from % Q6 X5 q6 [ C$ F9 Ito / C+ z W( L4 N& I$ }( to )， and then cooled slowly and uniformly to room Thermosetting plastics are brittle and sensitive to thermal gradients during Their machinability is generally similar to that of Because of the fibers present， reinforced plastics are very abrasive and are difficult to Fiber tearing， pulling， and edge delamination are significant problems; they can lead to severe reduction in the load-carrying capacity of the Furthermore， machining of these materials requires careful removal of machining debris to avoid contact with and inhaling of the The machinability of ceramics has improved steadily with the development of nanoceramics (Section 5) and with the selection of appropriate processing parameters， such as ductile-regime cutting (Section 2)Metal-matrix and ceramic-matrix composites can be difficult to machine， depending on the properties of the individual components， ， reinforcing or whiskers， as well as the matrix 4 Thermally Assisted MachiningMetals and alloys that are difficult to machine at room temperature can be machined more easily at elevated In thermally assisted machining (hot machining)， the source of heat—a torch， induction coil， high-energy beam (such as laser or electron beam)， or plasma arc—is forces， (b) increased tool life， (c) use of inexpensive cutting-tool materials， (d) higher material-removal rates， and (e) reduced tendency for vibration and It may be difficult to heat and maintain a uniform temperature distribution within the Also， the original microstructure of the workpiece may be adversely affected by elevated Most applications of hot machining are in the turning of high-strength metals and alloys， although experiments are in progress to machine ceramics such as silicon SUMMARY' k4 F( E u# |: n6 i6 hMachinability is usually defined in terms of surface finish， tool life， force and power requirements， and chip Machinability of materials depends not only on their intrinsic properties and microstructure， but also on proper selection and control of process 因文章太长，译文请点链接%3A///bbs/thread-27361-1-html
我也要，谢谢 ，急用
最简单的办法 - - 你去找一篇中文的 然后人肉翻译
机械专业英语论文3000字
200分确实不够起码2000分帮你
您好，您需要的3000字机械方面的英语文章（有出处）的文件已发至您的邮箱，请查收！希望我的回答对您有帮助，感谢您的支持，谢谢！
分很少啊 抽时间翻译 请稍等
A machine tool is a powered mechanical device， typically used to fabricate metal components of machines by machining， which is the selective removal of The term machine tool is usually reserved for tools that used a power source other than human movement， but they can be powered by people if appropriately set Many historians of technology consider that the true machine tools were born when direct human involvement was removed from the shaping or stamping process of the different kinds of The earliest lathe with direct mechanical control of the cutting tool was a screw-cutting lathe dating to about [1] This lathe "produced screw threads out of wood and employed a true compound slide rest"The first machine tools offered for sale ( commercially available) were constructed by one Matthew Murray in England around [2]Contents [hide]1 Overview 2 Examples 3 See also 4 References 5 Bibliography 6 Further reading 7 External links [edit] OverviewMachine tools can be powered from a variety of Human and animal power are options， as is energy captured through the use of However， modern machine tools began to develop only after the development of the steam engine， which led to the Industrial R Today， most machine tools are powered by Machine tools can be operated manually， or under automatic Early machines used flywheels to stabilize their motion and had complex systems of gears and levers to control the machine and the piece being worked Soon after World War II， the numerical control (NC) machine was NC machines used a series of numbers punched on paper tape or punch cards to control their In the 1960s， computers were added to give even more flexibility to the Such machines became known as computerized numerical control (CNC) NC and CNC machines could precisely repeat sequences over and over， and could produce much more complex pieces than even the most skilled tool Before long， the machines could automatically change the specific cutting and shaping tools that were being For example， a drill machine might contain a magazine with a variety of drill bits for producing holes of various Previously， either machine operators would usually have to manually change the bit or move the work piece to another station to perform these different The next logical step was to combine several different machine tools together， all under computer These are known as machining centers， and have dramatically changed the way parts are From the simplest to the most complex， most machine tools are capable of at least partial self-replication， and produce machine parts as their primary [edit] ExamplesExamples of machine tools are:Broaching machine Drill press Gear shaper Hobbing machine Hone Lathe Screw machines Milling machine Shaper Saws Planer Stewart platform mills Grinding machines When fabricating or shaping parts， several techniques are used to remove unwanted Among these are:Electrical discharge machining Grinding (abrasive cutting) Multiple edge cutting tools Single edge cutting tools Other techniques are used to add desired Devices that fabricate components by selective addition of material are called rapid prototyping Several regions of the United States became centers for machine tool development between 1800 and 1950， including Philadelphia， Pennsylvania; Cincinnati， Ohio; Rockford， Illinois; Providence， Rhode Island] Springfield， Vermont; Windsor， Vermont; Hartford， Connecticut; and Bridgeport， C 给你
机械专业英语论文3000字体
200分确实不够起码2000分帮你
原文：9 MACHINABILITYThe machinability of a material usually defined in terms of four factors:1、$ l m I `5 L* eSurface finish and integrity of the machined part;2、; u: I% F/ b$ t( O" ?' I2 MTool life obtained;3、1 F }: a% W1 W5 R l7 @* q; jForce and power requirements;4、 p) @0 }5 c* S+ I: IChip Thus， good machinability good surface finish and integrity， long tool life， and low force And power As for chip control， long and thin (stringy) cured chips， if not broken up， can severely interfere with the cutting operation by becoming entangled in the cutting Because of the complex nature of cutting operations， it is difficult to establish relationships that quantitatively define the machinability of a In manufacturing plants， tool life and surface roughness are generally considered to be the most important factors in Although not used much any more， approximate machinability ratings are available in the example 1 Machinability Of Steels6 }" `- x) E* V* T+ DBecause steels are among the most important engineering materials (as noted in Chapter 5)， their machinability has been studied The machinability of steels has been mainly improved by adding lead and sulfur to obtain so-called free-machining Resulfurized and Rephosphorized ， m# n- K R; @Sulfur in steels forms manganese sulfide inclusions (second-phase particles)， which act as stress raisers in the primary shear As a result， the chips produced break up easily and are small; this improves The size， shape， distribution， and concentration of these inclusions significantly influence Elements such as tellurium and selenium， which are both chemically similar to sulfur， act as inclusion modifiers in resulfurized Phosphorus in steels has two major It strengthens the ferrite， causing increased Harder steels result in better chip formation and surface Note that soft steels can be difficult to machine， with built-up edge formation and poor surface The second effect is that increased hardness causes the formation of short chips instead of continuous stringy ones， thereby improving Leaded S A high percentage of lead in steels solidifies at the tip of manganese sulfide In non-resulfurized grades of steel， lead takes the form of dispersed fine Lead is insoluble in iron， copper， and aluminum and their Because of its low shear strength， therefore， lead acts as a solid lubricant (Section 11) and is smeared over the tool-chip interface during This behavior has been verified by the presence of high concentrations of lead on the tool-side face of chips when machining leaded When the temperature is sufficiently high-for instance， at high cutting speeds and feeds (Section 6)—the lead melts directly in front of the tool， acting as a liquid In addition to this effect， lead lowers the shear stress in the primary shear zone， reducing cutting forces and power Lead can be used in every grade of steel， such as 10xx， 11xx， 12xx， 41xx， Leaded steels are identified by the letter L between the second and third numerals (for example， 10L45) (Note that in stainless steels， similar use of the letter L means “low carbon，” a condition that improves their corrosion )However， because lead is a well-known toxin and a pollutant， there are serious environmental concerns about its use in steels (estimated at 4500 tons of lead consumption every year in the production of steels) Consequently， there is a continuing trend toward eliminating the use of lead in steels (lead-free steels) Bismuth and tin are now being investigated as possible substitutes for lead in Calcium-Deoxidized S An important development is calcium-deoxidized steels， in which oxide flakes of calcium silicates (CaSo) are These flakes， in turn， reduce the strength of the secondary shear zone， decreasing tool-chip interface and Temperature is correspondingly Consequently， these steels produce less crater wear， especially at high cutting Stainless S Austenitic (300 series) steels are generally difficult to Chatter can be s problem， necessitating machine tools with high However， ferritic stainless steels (also 300 series) have good Martensitic (400 series) steels are abrasive， tend to form a built-up edge， and require tool materials with high hot hardness and crater-wear Precipitation-hardening stainless steels are strong and abrasive， requiring hard and abrasion-resistant tool The Effects of Other Elements in Steels on M The presence of aluminum and silicon in steels is always harmful because these elements combine with oxygen to form aluminum oxide and silicates， which are hard and These compounds increase tool wear and reduce It is essential to produce and use clean Carbon and manganese have various effects on the machinability of steels， depending on their Plain low-carbon steels (less than 15% C) can produce poor surface finish by forming a built-up Cast steels are more abrasive， although their machinability is similar to that of wrought Tool and die steels are very difficult to machine and usually require annealing prior to Machinability of most steels is improved by cold working， which hardens the material and reduces the tendency for built-up edge Other alloying elements， such as nickel， chromium， molybdenum， and vanadium， which improve the properties of steels， generally reduce The effect of boron is Gaseous elements such as hydrogen and nitrogen can have particularly detrimental effects on the properties of Oxygen has been shown to have a strong effect on the aspect ratio of the manganese sulfide inclusions; the higher the oxygen content， the lower the aspect ratio and the higher the In selecting various elements to improve machinability， we should consider the possible detrimental effects of these elements on the properties and strength of the machined part in At elevated temperatures， for example， lead causes embrittlement of steels (liquid-metal embrittlement， hot shortness; see Section 3)， although at room temperature it has no effect on mechanical Sulfur can severely reduce the hot workability of steels， because of the formation of iron sulfide， unless sufficient manganese is present to prevent such At room temperature， the mechanical properties of resulfurized steels depend on the orientation of the deformed manganese sulfide inclusions (anisotropy) Rephosphorized steels are significantly less ductile， and are produced solely to improve 2 Machinability of Various Other MetalsAluminum is generally very easy to machine， although the softer grades tend to form a built-up edge， resulting in poor surface High cutting speeds， high rake angles， and high relief angles are Wrought aluminum alloys with high silicon content and cast aluminum alloys may be abrasive; they require harder tool Dimensional tolerance control may be a problem in machining aluminum， since it has a high thermal coefficient of expansion and a relatively low elastic Beryllium is similar to cast Because it is more abrasive and toxic， though， it requires machining in a controlled Cast gray irons are generally machinable but Free carbides in castings reduce their machinability and cause tool chipping or fracture， necessitating tools with high Nodular and malleable irons are machinable with hard tool Cobalt-based alloys are abrasive and highly work- They require sharp， abrasion-resistant tool materials and low feeds and Wrought copper can be difficult to machine because of built-up edge formation， although cast copper alloys are easy to Brasses are easy to machine， especially with the addition pf lead (leaded free-machining brass) Bronzes are more difficult to machine than Magnesium is very easy to machine， with good surface finish and prolonged tool However care should be exercised because of its high rate of oxidation and the danger of fire (the element is pyrophoric)Molybdenum is ductile and work-hardening， so it can produce poor surface Sharp tools are Nickel-based alloys are work-hardening， abrasive， and strong at high Their machinability is similar to that of stainless Tantalum is very work-hardening， ductile， and It produces a poor surface finish; tool wear is Titanium and its alloys have poor thermal conductivity (indeed， the lowest of all metals)， causing significant temperature rise and built-up edge; they can be difficult to Tungsten is brittle， strong， and very abrasive， so its machinability is low， although it greatly improves at elevated Zirconium has good It requires a coolant-type cutting fluid， however， because of the explosion and 3 Machinability of Various Materials; n+ {0 C# N' t: K& D5 Y7 nGraphite is abrasive; it requires hard， abrasion-resistant， sharp Thermoplastics generally have low thermal conductivity， low elastic modulus， and low softening Consequently， machining them requires tools with positive rake angles (to reduce cutting forces)， large relief angles， small depths of cut and feed， relatively high speeds， andproper support of the Tools should be External cooling of the cutting zone may be necessary to keep the chips from becoming “gummy” and sticking to the Cooling can usually be achieved with a jet of air， vapor mist， or water-soluble Residual stresses may develop during To relieve these stresses， machined parts can be annealed for a period of time at temperatures ranging from % Q6 X5 q6 [ C$ F9 Ito / C+ z W( L4 N& I$ }( to )， and then cooled slowly and uniformly to room Thermosetting plastics are brittle and sensitive to thermal gradients during Their machinability is generally similar to that of Because of the fibers present， reinforced plastics are very abrasive and are difficult to Fiber tearing， pulling， and edge delamination are significant problems; they can lead to severe reduction in the load-carrying capacity of the Furthermore， machining of these materials requires careful removal of machining debris to avoid contact with and inhaling of the The machinability of ceramics has improved steadily with the development of nanoceramics (Section 5) and with the selection of appropriate processing parameters， such as ductile-regime cutting (Section 2)Metal-matrix and ceramic-matrix composites can be difficult to machine， depending on the properties of the individual components， ， reinforcing or whiskers， as well as the matrix 4 Thermally Assisted MachiningMetals and alloys that are difficult to machine at room temperature can be machined more easily at elevated In thermally assisted machining (hot machining)， the source of heat—a torch， induction coil， high-energy beam (such as laser or electron beam)， or plasma arc—is forces， (b) increased tool life， (c) use of inexpensive cutting-tool materials， (d) higher material-removal rates， and (e) reduced tendency for vibration and It may be difficult to heat and maintain a uniform temperature distribution within the Also， the original microstructure of the workpiece may be adversely affected by elevated Most applications of hot machining are in the turning of high-strength metals and alloys， although experiments are in progress to machine ceramics such as silicon SUMMARY' k4 F( E u# |: n6 i6 hMachinability is usually defined in terms of surface finish， tool life， force and power requirements， and chip Machinability of materials depends not only on their intrinsic properties and microstructure， but also on proper selection and control of process 因文章太长，译文请点链接%3A///bbs/thread-27361-1-html
这里有很多的，你可以找下有没有?我找了好长时间才找到的哦中文免费论文地址集锦 一、 综合类 1、蓝之韵论文 门类较全。 2、学生大论文中心 3、蜂朝无忧论文网 门类很全。 4、论文下载中心 门类很全。 5、论文帝国 二、 教育类 1、教研论文交流中心 以中小学教育为主，基础教育、英语教学文章居多。 2、教育教学论文网 以教育论文为主，包含：语文论文 美术论文 物理论文 化学论文 英语论文 历史论文 德育论文 教学论文 数学论文 音乐论文 生物论文 自然论文 体育论文 地理论文 摄影论文 劳动技术 农村教育 毕业论文 素质论文 医学论文 电子电器学 思维科学 计算机论文 活动课教学 书法篆刻论文 创新教育研究 心理健康教育 西部教育论文 信息技术论文 3、教育论文 -/asp 4、中国园丁网论文大观 5、北大附小学校教师的文章： 三、 专业类 1、优秀论文杂志 以科技类为主。 2、论文资料网 以财经经济管理类为主。 3、法律图书馆 -/ 文如其名。 4、法学论文资料库 -/lw/ 文如其名。 5、中国总经理网论文集 6、mba职业经理人论坛 7、中国农业在线-农业论文 8、体育论文 9、财经学位论文下载中心 10、公开发表论文_深圳证券交易所 11、中国路桥资讯网论文资料中心 12、论文商务中心 13、法律帝国： 四、 论文写作教学类 1、学术论文 其实是学术论文的写作网站。 五、 博硕士论文 1、论文统计 实际上就是万方的论文统计。 2、台湾博硕士论文咨讯网 3、北京大学学位论文样本收藏 4、学位论文 （清华大学） ] 中国科技论文在线 论文中国 : 新浪论文网分类:_dir/jy/lw/ 中国论文联盟: 大学生论文库 论文资料网: 论文下载中心: 毕业论文网: 学位论文: 无忧论文网: 北京语言文化大学论文库:
机械专业英语论文3000字数
200分确实不够起码2000分帮你
原文：9 MACHINABILITYThe machinability of a material usually defined in terms of four factors:1、$ l m I `5 L* eSurface finish and integrity of the machined part;2、; u: I% F/ b$ t( O" ?' I2 MTool life obtained;3、1 F }: a% W1 W5 R l7 @* q; jForce and power requirements;4、 p) @0 }5 c* S+ I: IChip Thus， good machinability good surface finish and integrity， long tool life， and low force And power As for chip control， long and thin (stringy) cured chips， if not broken up， can severely interfere with the cutting operation by becoming entangled in the cutting Because of the complex nature of cutting operations， it is difficult to establish relationships that quantitatively define the machinability of a In manufacturing plants， tool life and surface roughness are generally considered to be the most important factors in Although not used much any more， approximate machinability ratings are available in the example 1 Machinability Of Steels6 }" `- x) E* V* T+ DBecause steels are among the most important engineering materials (as noted in Chapter 5)， their machinability has been studied The machinability of steels has been mainly improved by adding lead and sulfur to obtain so-called free-machining Resulfurized and Rephosphorized ， m# n- K R; @Sulfur in steels forms manganese sulfide inclusions (second-phase particles)， which act as stress raisers in the primary shear As a result， the chips produced break up easily and are small; this improves The size， shape， distribution， and concentration of these inclusions significantly influence Elements such as tellurium and selenium， which are both chemically similar to sulfur， act as inclusion modifiers in resulfurized Phosphorus in steels has two major It strengthens the ferrite， causing increased Harder steels result in better chip formation and surface Note that soft steels can be difficult to machine， with built-up edge formation and poor surface The second effect is that increased hardness causes the formation of short chips instead of continuous stringy ones， thereby improving Leaded S A high percentage of lead in steels solidifies at the tip of manganese sulfide In non-resulfurized grades of steel， lead takes the form of dispersed fine Lead is insoluble in iron， copper， and aluminum and their Because of its low shear strength， therefore， lead acts as a solid lubricant (Section 11) and is smeared over the tool-chip interface during This behavior has been verified by the presence of high concentrations of lead on the tool-side face of chips when machining leaded When the temperature is sufficiently high-for instance， at high cutting speeds and feeds (Section 6)—the lead melts directly in front of the tool， acting as a liquid In addition to this effect， lead lowers the shear stress in the primary shear zone， reducing cutting forces and power Lead can be used in every grade of steel， such as 10xx， 11xx， 12xx， 41xx， Leaded steels are identified by the letter L between the second and third numerals (for example， 10L45) (Note that in stainless steels， similar use of the letter L means “low carbon，” a condition that improves their corrosion )However， because lead is a well-known toxin and a pollutant， there are serious environmental concerns about its use in steels (estimated at 4500 tons of lead consumption every year in the production of steels) Consequently， there is a continuing trend toward eliminating the use of lead in steels (lead-free steels) Bismuth and tin are now being investigated as possible substitutes for lead in Calcium-Deoxidized S An important development is calcium-deoxidized steels， in which oxide flakes of calcium silicates (CaSo) are These flakes， in turn， reduce the strength of the secondary shear zone， decreasing tool-chip interface and Temperature is correspondingly Consequently， these steels produce less crater wear， especially at high cutting Stainless S Austenitic (300 series) steels are generally difficult to Chatter can be s problem， necessitating machine tools with high However， ferritic stainless steels (also 300 series) have good Martensitic (400 series) steels are abrasive， tend to form a built-up edge， and require tool materials with high hot hardness and crater-wear Precipitation-hardening stainless steels are strong and abrasive， requiring hard and abrasion-resistant tool The Effects of Other Elements in Steels on M The presence of aluminum and silicon in steels is always harmful because these elements combine with oxygen to form aluminum oxide and silicates， which are hard and These compounds increase tool wear and reduce It is essential to produce and use clean Carbon and manganese have various effects on the machinability of steels， depending on their Plain low-carbon steels (less than 15% C) can produce poor surface finish by forming a built-up Cast steels are more abrasive， although their machinability is similar to that of wrought Tool and die steels are very difficult to machine and usually require annealing prior to Machinability of most steels is improved by cold working， which hardens the material and reduces the tendency for built-up edge Other alloying elements， such as nickel， chromium， molybdenum， and vanadium， which improve the properties of steels， generally reduce The effect of boron is Gaseous elements such as hydrogen and nitrogen can have particularly detrimental effects on the properties of Oxygen has been shown to have a strong effect on the aspect ratio of the manganese sulfide inclusions; the higher the oxygen content， the lower the aspect ratio and the higher the In selecting various elements to improve machinability， we should consider the possible detrimental effects of these elements on the properties and strength of the machined part in At elevated temperatures， for example， lead causes embrittlement of steels (liquid-metal embrittlement， hot shortness; see Section 3)， although at room temperature it has no effect on mechanical Sulfur can severely reduce the hot workability of steels， because of the formation of iron sulfide， unless sufficient manganese is present to prevent such At room temperature， the mechanical properties of resulfurized steels depend on the orientation of the deformed manganese sulfide inclusions (anisotropy) Rephosphorized steels are significantly less ductile， and are produced solely to improve 2 Machinability of Various Other MetalsAluminum is generally very easy to machine， although the softer grades tend to form a built-up edge， resulting in poor surface High cutting speeds， high rake angles， and high relief angles are Wrought aluminum alloys with high silicon content and cast aluminum alloys may be abrasive; they require harder tool Dimensional tolerance control may be a problem in machining aluminum， since it has a high thermal coefficient of expansion and a relatively low elastic Beryllium is similar to cast Because it is more abrasive and toxic， though， it requires machining in a controlled Cast gray irons are generally machinable but Free carbides in castings reduce their machinability and cause tool chipping or fracture， necessitating tools with high Nodular and malleable irons are machinable with hard tool Cobalt-based alloys are abrasive and highly work- They require sharp， abrasion-resistant tool materials and low feeds and Wrought copper can be difficult to machine because of built-up edge formation， although cast copper alloys are easy to Brasses are easy to machine， especially with the addition pf lead (leaded free-machining brass) Bronzes are more difficult to machine than Magnesium is very easy to machine， with good surface finish and prolonged tool However care should be exercised because of its high rate of oxidation and the danger of fire (the element is pyrophoric)Molybdenum is ductile and work-hardening， so it can produce poor surface Sharp tools are Nickel-based alloys are work-hardening， abrasive， and strong at high Their machinability is similar to that of stainless Tantalum is very work-hardening， ductile， and It produces a poor surface finish; tool wear is Titanium and its alloys have poor thermal conductivity (indeed， the lowest of all metals)， causing significant temperature rise and built-up edge; they can be difficult to Tungsten is brittle， strong， and very abrasive， so its machinability is low， although it greatly improves at elevated Zirconium has good It requires a coolant-type cutting fluid， however， because of the explosion and 3 Machinability of Various Materials; n+ {0 C# N' t: K& D5 Y7 nGraphite is abrasive; it requires hard， abrasion-resistant， sharp Thermoplastics generally have low thermal conductivity， low elastic modulus， and low softening Consequently， machining them requires tools with positive rake angles (to reduce cutting forces)， large relief angles， small depths of cut and feed， relatively high speeds， andproper support of the Tools should be External cooling of the cutting zone may be necessary to keep the chips from becoming “gummy” and sticking to the Cooling can usually be achieved with a jet of air， vapor mist， or water-soluble Residual stresses may develop during To relieve these stresses， machined parts can be annealed for a period of time at temperatures ranging from % Q6 X5 q6 [ C$ F9 Ito / C+ z W( L4 N& I$ }( to )， and then cooled slowly and uniformly to room Thermosetting plastics are brittle and sensitive to thermal gradients during Their machinability is generally similar to that of Because of the fibers present， reinforced plastics are very abrasive and are difficult to Fiber tearing， pulling， and edge delamination are significant problems; they can lead to severe reduction in the load-carrying capacity of the Furthermore， machining of these materials requires careful removal of machining debris to avoid contact with and inhaling of the The machinability of ceramics has improved steadily with the development of nanoceramics (Section 5) and with the selection of appropriate processing parameters， such as ductile-regime cutting (Section 2)Metal-matrix and ceramic-matrix composites can be difficult to machine， depending on the properties of the individual components， ， reinforcing or whiskers， as well as the matrix 4 Thermally Assisted MachiningMetals and alloys that are difficult to machine at room temperature can be machined more easily at elevated In thermally assisted machining (hot machining)， the source of heat—a torch， induction coil， high-energy beam (such as laser or electron beam)， or plasma arc—is forces， (b) increased tool life， (c) use of inexpensive cutting-tool materials， (d) higher material-removal rates， and (e) reduced tendency for vibration and It may be difficult to heat and maintain a uniform temperature distribution within the Also， the original microstructure of the workpiece may be adversely affected by elevated Most applications of hot machining are in the turning of high-strength metals and alloys， although experiments are in progress to machine ceramics such as silicon SUMMARY' k4 F( E u# |: n6 i6 hMachinability is usually defined in terms of surface finish， tool life， force and power requirements， and chip Machinability of materials depends not only on their intrinsic properties and microstructure， but also on proper selection and control of process 因文章太长，译文请点链接%3A///bbs/thread-27361-1-html
去国外的大学教授主页上找吧，一般他们都会公布自己写的论文。这上面都一些机械控制的论文，不知道是不是符合你的要求 上面那个连接随便点一个进去就是一篇论文。。。 这就是论文了 这是第二篇
机械英语论文3000字怎么写
A machine tool is a powered mechanical device， typically used to fabricate metal components of machines by machining， which is the selective removal of The term machine tool is usually reserved for tools that used a power source other than human movement， but they can be powered by people if appropriately set Many historians of technology consider that the true machine tools were born when direct human involvement was removed from the shaping or stamping process of the different kinds of The earliest lathe with direct mechanical control of the cutting tool was a screw-cutting lathe dating to about [1] This lathe "produced screw threads out of wood and employed a true compound slide rest"The first machine tools offered for sale ( commercially available) were constructed by one Matthew Murray in England around [2]Contents [hide]1 Overview 2 Examples 3 See also 4 References 5 Bibliography 6 Further reading 7 External links [edit] OverviewMachine tools can be powered from a variety of Human and animal power are options， as is energy captured through the use of However， modern machine tools began to develop only after the development of the steam engine， which led to the Industrial R Today， most machine tools are powered by Machine tools can be operated manually， or under automatic Early machines used flywheels to stabilize their motion and had complex systems of gears and levers to control the machine and the piece being worked Soon after World War II， the numerical control (NC) machine was NC machines used a series of numbers punched on paper tape or punch cards to control their In the 1960s， computers were added to give even more flexibility to the Such machines became known as computerized numerical control (CNC) NC and CNC machines could precisely repeat sequences over and over， and could produce much more complex pieces than even the most skilled tool Before long， the machines could automatically change the specific cutting and shaping tools that were being For example， a drill machine might contain a magazine with a variety of drill bits for producing holes of various Previously， either machine operators would usually have to manually change the bit or move the work piece to another station to perform these different The next logical step was to combine several different machine tools together， all under computer These are known as machining centers， and have dramatically changed the way parts are From the simplest to the most complex， most machine tools are capable of at least partial self-replication， and produce machine parts as their primary [edit] ExamplesExamples of machine tools are:Broaching machine Drill press Gear shaper Hobbing machine Hone Lathe Screw machines Milling machine Shaper Saws Planer Stewart platform mills Grinding machines When fabricating or shaping parts， several techniques are used to remove unwanted Among these are:Electrical discharge machining Grinding (abrasive cutting) Multiple edge cutting tools Single edge cutting tools Other techniques are used to add desired Devices that fabricate components by selective addition of material are called rapid prototyping Several regions of the United States became centers for machine tool development between 1800 and 1950， including Philadelphia， Pennsylvania; Cincinnati， Ohio; Rockford， Illinois; Providence， Rhode Island] Springfield， Vermont; Windsor， Vermont; Hartford， Connecticut; and Bridgeport， C
我也要，谢谢 ，急用
论文是用钱买的，这些分不够啊？呵呵呵
管道支吊架 Pipe Supports and H1 管架零部件 Attachment of Support管托 shoe管卡 clampU形夹（卡） clevis锻制U形夹 forged steel clevis支耳；吊耳 lug; ear耳轴 trunnion止动挡块 shear lug托座 stool托架 cradle带状卡 strap clamp夹板，导向板 cleat可调夹板 adjustable cleat角板；连接板 gusset筋；肋 rib支承环 ring加强板 stiffiener底板 base plate顶板 top plate翅片式导向板 fin预埋件 embedded part; inserted plate垫板（安装垫平用） shim锚固件；生根件 clip预焊件(设备上) clip (on equipment)聚四氟乙烯滑动板 PTFE sliding plate连接板 tie plate连接杆 tie rod限制杆 limit rod带环头拉杆 eye rod连接杆 connecting rod杠杆 lever支撑杆 strut定位块 preset pieces间隔管（片、块） spacer滑动吊板（吊架顶部用） sliding traveler(for hanger)滑轮组 tackle-block钢索，电缆 cable木块 wood block鞍座 saddle裙座 skirt软管卷盘（简） hose reel管部附着件 pipe 2 管支架型式 Type of Pipe Support支承架 resting support滑动架 sliding support固定架 anchor导向架 guide限制性支架；约束 restraint限位架 stop限位器 stopper定值限位架 limit stop二维限位架 two-axis stop往复定值限位架 double-acting limit stop定向限位架 directional stop吊架 hanger弹簧架 spring support弹簧托架 resting type spring support弹簧吊架 spring hanger恒力吊架 constant hanger重锤式吊架 counter weight hanger弹簧恒力吊架 spring constant hanger弹簧恒力托架 resting type spring constant support滚动支架 rolling support弹簧支撑架 spring bracing减振器 snubber液压减振器 hydraulic snubber减振装置 damping device缓冲简（器） dash pot刚性吊架 rigid 3 标准及通用型支架标准管架 standard pipe support通用管架 typical pipe support悬臂架 cantilever support三角架 triangular support’支腿 legⅡ形管架 Ⅱ-type supportL形管架 L-type support柱式管架 pole type support墙架 support on wall可调支架 adjustable support管墩，低管架 sleeper特殊管架 special support管道支吊架图 piping support 4 管架安装背至背 back to back钻孔 drill长孔 slot; slot hole放气孔；通气孔 vent hole灌浆；水泥砂浆填平 grouting组装；装配 assembly攻螺孔 apping自由滑动 free to slide跨度 span对中心；找正 alignment切割使适合 cut to suit修饰使适合 trim to suit伸出长度（指预埋螺栓） extrusion液压试验中，对试验液体要求是：试验液体一般采用水，需要时也可采用不会导致发生危险的其它液体。试验时液体的温度应低于其闪点或沸点。奥氏体不锈钢制容器用水进行液压试验后应将水渍去除干净。当无法达到这一要求时，应控制水的氯离子含量不超过25mmg/L试验温度：1． 碳素钢、16MnR和正火15MnVR钢制压力容器液压试验时，液体温度不得低于5℃，其它低合金钢制容器液压试验时液体温度不得低于15℃。如果由于板厚等原因造成材料延性转变温度升高，则需相应提高试验液体温度。2． 其它钢种制容器液压试验温度按图样规定。