机械 毕业文 外文翻译 摘制造工程技术（机加工）
外语文献翻译
摘 制造工程技术(机加工)(英文版)
Manufacturing Engineering and TechnologyMachining
机械工业出版社 2004年3月第1版
美 s 卡尔帕基安Serope kalpakjian
sr 施密德Steven RSchmid 著
原文209 MACHINABILITY
The machinability of a material usually defined in terms of four factors
Surface finish and integrity of the machined part
Tool life obtained
Force and power requirements
Chip control Thus good machinability good surface finish and integrity long tool life and low force And power requirements 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 zone
Because of the complex nature of cutting operations it is difficult to establish relationships that quantitatively define the machinability of a material In manufacturing plants tool life and surface roughness are generally considered to be the most important factors in machinability Although not used much any more approximate machinability ratings are available in the example below
2091 Machinability Of Steels
Because steels are among the most important engineering materials as noted in Chapter 5 their machinability has been studied extensively The machinability of steels has been mainly improved by adding lead and sulfur to obtain socalled freemachining steels
Resulfurized and Rephosphorized steelsSulfur in steels forms manganese sulfide inclusions secondphase particles which act as stress raisers in the primary shear zone As a result the chips produced break up easily and are small this improves machinability The size shape distribution and concentration of these inclusions significantly influence machinability Elements such as tellurium and selenium which are both chemically similar to sulfur act as inclusion modifiers in resulfurized steels
Phosphorus in steels has two major effects It strengthens the ferrite causing increased hardness Harder steels result in better chip formation and surface finish Note that soft steels can be difficult to machine with builtup edge formation and poor surface finish The second effect is that increased hardness causes the formation of short chips instead of continuous stringy ones thereby improving machinability
Leaded Steels A high percentage of lead in steels solidifies at the tip of manganese sulfide inclusions In nonresulfurized grades of steel lead takes the form of dispersed fine particles Lead is insoluble in iron copper and aluminum and their alloys Because of its low shear strength therefore lead acts as a solid lubricant Section 3211 and is smeared over the toolchip interface during cutting This behavior has been verified by the presence of high concentrations of lead on the toolside face of chips when machining leaded steels
When the temperature is sufficiently highfor instance at high cutting speeds and feeds Section 206the lead melts directly in front of the tool acting as a liquid lubricant In addition to this effect lead lowers the shear stress in the primary shear zone reducing cutting forces and power consumption Lead can be used in every grade of steel such as 10xx 11xx 12xx 41xx etc 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 resistance
However because lead is a wellknown 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 leadfree steels Bismuth and tin are now being investigated as possible substitutes for lead in steels
CalciumDeoxidized Steels An important development is calciumdeoxidized steels in which oxide flakes of calcium silicates CaSo are formed These flakes in turn reduce the strength of the secondary shear zone decreasing toolchip interface and wear Temperature is correspondingly reduced Consequently these steels produce less crater wear especially at high cutting speeds
Stainless Steels Austenitic 300 series steels are generally difficult to machine Chatter can be s problem necessitating machine tools with high stiffness However ferritic stainless steels also 300 series have good machinability Martensitic 400 series steels are abrasive tend to form a builtup edge and require tool materials with high hot hardness and craterwear resistance Precipitationhardening stainless steels are strong and abrasive requiring hard and abrasionresistant tool materials
The Effects of Other Elements in Steels on Machinability 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 abrasive These compounds increase tool wear and reduce machinability It is essential to produce and use clean steels
Carbon and manganese have various effects on the machinability of steels depending on their composition Plain lowcarbon steels less than 015 C can produce poor surface finish by forming a builtup edge Cast steels are more abrasive although their machinability is similar to that of wrought steels Tool and die steels are very difficult to machine and usually require annealing prior to machining Machinability of most steels is improved by cold working which hardens the material and reduces the tendency for builtup edge formation
Other alloying elements such as nickel chromium molybdenum and vanadium which improve the properties of steels generally reduce machinability The effect of boron is negligible Gaseous elements such as hydrogen and nitrogen can have particularly detrimental effects on the properties of steel 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 machinability
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 service At elevated temperatures for example lead causes embrittlement of steels liquidmetal embrittlement hot shortness see Section 143 although at room temperature it has no effect on mechanical properties
Sulfur can severely reduce the hot workability of steels because of the formation of iron sulfide unless sufficient manganese is present to prevent such formation 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 machinability
2092 Machinability of Various Other Metals
Aluminum is generally very easy to machine although the softer grades tend to form a builtup edge resulting in poor surface finish High cutting speeds high rake angles and high relief angles are recommended Wrought aluminum alloys with high silicon content and cast aluminum alloys may be abrasive they require harder tool materials Dimensional tolerance control may be a problem in machining aluminum since it has a high thermal coefficient of expansion and a relatively low elastic modulus
Beryllium is similar to cast irons Because it is more abrasive and toxic though it requires machining in a controlled environment
Cast gray irons are generally machinable but are Free carbides in castings reduce their machinability and cause tool chipping or fracture necessitating tools with high toughness Nodular and malleable irons are machinable with hard tool materials
Cobaltbased alloys are abrasive and highly workhardening They require sharp abrasionresistant tool materials and low feeds and speeds
Wrought copper can be difficult to machine because of builtup edge formation although cast copper alloys are easy to machine Brasses are easy to machine especially with the addition pf lead leaded freemachining brass Bronzes are more difficult to machine than brass
Magnesium is very easy to machine with good surface finish and prolonged tool life 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 workhardening so it can produce poor surface finish Sharp tools are necessary
Nickelbased alloys are workhardening abrasive and strong at high temperatures Their machinability is similar to that of stainless steels
Tantalum is very workhardening ductile and soft It produces a poor surface finish tool wear is high
Titanium and its alloys have poor thermal conductivity indeed the lowest of all metals causing significant temperature rise and builtup edge they can be difficult to machine
Tungsten is brittle strong and very abrasive so its machinability is low although it greatly improves at elevated temperatures
Zirconium has good machinability It requires a coolanttype cutting fluid however because of the explosion and fire
2093 Machinability of Various Materials
Graphite is abrasive it requires hard abrasionresistant sharp tools
Thermoplastics generally have low thermal conductivity low elastic modulus and low softening temperature 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 and
proper support of the workpiece Tools should be sharp
External cooling of the cutting zone may be necessary to keep the chips from becoming gummy and sticking to the tools Cooling can usually be achieved with a jet of air vapor mist or watersoluble oils Residual stresses may develop during machining To relieve these stresses machined parts can be annealed for a period of time at temperatures ranging from to to and then cooled slowly and uniformly to room temperature
Thermosetting plastics are brittle and sensitive to thermal gradients during cutting Their machinability is generally similar to that of thermoplastics
Because of the fibers present reinforced plastics are very abrasive and are difficult to machine Fiber tearing pulling and edge delamination are significant problems they can lead to severe reduction in the loadcarrying capacity of the component Furthermore machining of these materials requires careful removal of machining debris to avoid contact with and inhaling of the fibers
The machinability of ceramics has improved steadily with the development of nanoceramics Section 825 and with the selection of appropriate processing parameters such as ductileregime cutting Section 2242
Metalmatrix and ceramicmatrix composites can be difficult to machine depending on the properties of the individual components ie reinforcing or whiskers as well as the matrix material
2094 Thermally Assisted Machining
Metals and alloys that are difficult to machine at room temperature can be machined more easily at elevated temperatures In thermally assisted machining hot machining the source of heata torch induction coil highenergy beam such as laser or electron beam or plasma arcis forces b increased tool life c use of inexpensive cuttingtool materials d higher materialremoval rates and e reduced tendency for vibration and chatter
It may be difficult to heat and maintain a uniform temperature distribution within the workpiece Also the original microstructure of the workpiece may be adversely affected by elevated temperatures Most applications of hot machining are in the turning of highstrength metals and alloys although experiments are in progress to machine ceramics such as silicon nitrideSUMMARY
Machinability is usually defined in terms of surface finish tool life force and power requirements and chip control Machinability of materials depends not only on their intrinsic properties and microstructure but also on proper selection and control of process variables
译文
209 机加工性
种材料机加工性通常四种素方式定义
材料表面光洁性表面完整性
2刀具寿命
3切削力功率需求
4切屑控制
种方式机加工性指表面光洁性完整性长刀具寿命低切削力功率需求关切屑控制细长卷曲切屑果没切割成片切屑区变混乱缠起方式够严重介入剪切工序
剪切工序复杂属性难建立定量释义材料机加工性关系制造厂里刀具寿命表面粗糙度通常认机加工性中重素已量准确机加工率例子中够常
2091 钢机加工性
钢重工程材料(正第5章示)机加工性已广泛研究通添加铅硫磺钢机加工性已提高谓易切削钢
二次硫化钢二次磷化钢硫钢中形成硫化锰夹杂物(第二相粒子)夹杂物第剪切区引起应力结果切屑容易断开变改善加工性夹杂物形状分布集中程度显著影响材料加工性化学元素碲硒化学性质硫类似二次硫化钢中起夹杂物改性作
钢中磷两方面影响第影响加强铁素体增加硬度越硬钢形成更切屑形成更表面光洁性需注意软钢适合积屑瘤形成差表面光洁性机器第二影响增加钢硬度引起短切屑断细长切屑形成提高切削加工性
含铅钢钢中高含量铅硫化锰夹杂物尖端析出非二次硫化钢中铅呈细分散颗粒铅铁铜铝合金中溶解低抗剪强度铅充固体润滑剂切削时涂刀具切屑接口处特性已机加工铅钢时切屑刀具面表面高浓度铅存证实
温度足够高时例高切削速度进速度铅刀具前直接熔化充液体润滑剂种效应铅降低第剪切区中剪应力减切削力功率消耗铅种钢号例10XX11XX12XX41XX等等铅钢第二第三数码中字母L识(例10L45)(需注意锈钢中字母L相法指低碳提高耐蚀性条件)
然铅名毒素污染物钢中存着严重环境隐患(钢产品中年约4500吨铅消耗)结果估算钢中含铅量存持续趋势铋锡现正作钢中铅代物深入研究
脱氧钙钢重发展脱氧钙钢脱氧钙钢中矽酸钙盐中氧化物片形成薄片次减第二剪切区中力量降低刀具切屑接口处摩擦磨损温度相应降低结果钢产生更月牙洼磨损特高切削速度时更
锈钢奥氏体钢通常难机加工振动成问题需高硬度高强度机床然铁素体锈钢具良机加工性马氏体钢易磨蚀易形成积屑瘤求刀具材料高热硬度耐月牙洼磨损性沉淀硬化锈钢强度高磨蚀性强求刀具材料硬耐磨
钢中元素机加工性方面影响钢中铝硅存总害元素结合氧会生成氧化铝矽酸盐氧化铝硅酸盐硬具磨蚀性化合物增加刀具磨损降低机加工性生产净化钢非常必
根构成碳锰钢钢机加工性方面影响低碳素钢(少015碳)通形成积屑瘤生成差表面光洁性铸钢机加工性锻钢致相铸钢具更磨蚀性刀具模具钢难机加工通常煅烧机加工数钢机加工性冷加工提高冷加工材料变硬减少积屑瘤形成
合金元素例镍铬钳钒提高钢特性减机加工性硼影响忽视气态元素氢氮钢特性方面特害影响氧已证明硫化锰夹杂物横方面强影响越高含氧量产生越低横越高机加工性
选择种元素改善加工性应该考虑元素已加工零件中性强度利影响例温度升高时铝会钢变脆(液体金属脆化热脆化见143节)室温力学性没影响
硫化铁构成硫严重减少钢热加工性非足够锰防止种结构形成室温二次磷化钢机械性赖变形硫化锰夹杂物定位(异性)二次磷化钢具更延展性单独生成提高机加工性
2092 金属机加工性
铝通常容易机加工越软品种易生成积屑瘤造成差表面光洁性高切削速度高前角高角推荐高含量矽锻铝合金铸铝合金许具磨蚀性求更硬刀具材料尺寸公差控制许机加工铝时会成问题高热膨胀系数相低弹性模数
铍类似铸铁更具磨蚀性毒性求控工环境进行机加工
灰铸铁普遍加工磨蚀性铸造中游离碳化物降低机加工性引起刀具切屑裂口需具强韧性工具具坚硬刀具材料球墨铸铁韧性铁加工
钴基合金磨蚀性高度加工硬化求锋利具耐蚀性刀具材料低进刀速度
铸铜合金容易机加工锻铜积屑瘤形成锻铜难机加工黄铜容易机加工特添加铅更容易青铜黄铜更难机加工
镁容易机加工镁表面光洁性长久刀具寿命然高氧化速度火灾危险(种元素易燃)应该特心
钳易拉长加工硬化生成差表面光洁性尖刀具必
镍基合金加工硬化具磨蚀性高温非常坚硬机加工性锈钢相
钽非常加工硬化具延性柔软生成高表面光洁性刀具磨损非常
钛合金导热性确金属中低引起明显温度升高积屑瘤难机加工
钨易脆坚硬具磨蚀性性高温提高机加工性低
锆机加工性然爆炸火种危险性求冷性质切削液
2093 种材料机加工性
石墨具磨蚀性求硬尖具耐蚀性刀具
塑性塑料通常低导热系数低弹性模量低软化温度机加工热塑性塑料求正前角刀具(降低切削力)求角切削走刀深相高速度工件正确支承刀具应该尖
切削区外部冷许必防止切屑变黏性粘刀具空气流汽雾水溶性油通常实现冷机加工时残余应力许生成发展解力已机加工部分()温度范围冷段时间然慢慢变化冷室温
热固性塑料易脆切削时热梯度敏感机加工性热塑性塑料相
纤维存加强塑料具磨蚀性难机加工纤维撕裂拉出边界分层非常严重问题导致构成素承载力降材料机加工求加工残片仔细切避免接触吸进纤维
着纳米陶瓷(见825节)发展适参数处理选择例塑性切削(见2242节)陶瓷器机加工性已提高
金属基复合材料陶瓷基复合材料机加工赖单独成分特性说增强纤维金属须基体材料
2094 热辅助加工
室温难机加工金属合金高温更容易机加工热辅助加工时(高温切削)热源火感应线圈高束流(例雷射电子束)等离子弧集中切削刀具前块区域处(a)低切削力(b)增加刀具寿命(c)便宜切削刀具材料(d)更高材料切率(e)减少振动
许难工件加热保持变温度分布工件初微观结构许高温影响种影响相害实验进行中机加工陶瓷器氮化矽高温切削数应高强度金属高温度合金车削中
总结
通常零件机加工性根素定义表面粗糙度刀具寿命切削力功率需求切屑控制材料机加工性仅取决起特性微观结构赖工艺参数合理选择控制
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外语文献翻译
摘 制造工程技术(机加工)(英文版)
Manufacturing Engineering and TechnologyMachining
机械工业出版社 2004年3月第1版
美 s 卡尔帕基安Serope kalpakjian
sr 施密德Steven RSchmid 著
原文209 MACHINABILITY
The machinability of a material usually defined in terms of four factors
Surface finish and integrity of the machined part
Tool life obtained
Force and power requirements
Chip control Thus good machinability good surface finish and integrity long tool life and low force And power requirements 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 zone
Because of the complex nature of cutting operations it is difficult to establish relationships that quantitatively define the machinability of a material In manufacturing plants tool life and surface roughness are generally considered to be the most important factors in machinability Although not used much any more approximate machinability ratings are available in the example below
2091 Machinability Of Steels
Because steels are among the most important engineering materials as noted in Chapter 5 their machinability has been studied extensively The machinability of steels has been mainly improved by adding lead and sulfur to obtain socalled freemachining steels
Resulfurized and Rephosphorized steelsSulfur in steels forms manganese sulfide inclusions secondphase particles which act as stress raisers in the primary shear zone As a result the chips produced break up easily and are small this improves machinability The size shape distribution and concentration of these inclusions significantly influence machinability Elements such as tellurium and selenium which are both chemically similar to sulfur act as inclusion modifiers in resulfurized steels
Phosphorus in steels has two major effects It strengthens the ferrite causing increased hardness Harder steels result in better chip formation and surface finish Note that soft steels can be difficult to machine with builtup edge formation and poor surface finish The second effect is that increased hardness causes the formation of short chips instead of continuous stringy ones thereby improving machinability
Leaded Steels A high percentage of lead in steels solidifies at the tip of manganese sulfide inclusions In nonresulfurized grades of steel lead takes the form of dispersed fine particles Lead is insoluble in iron copper and aluminum and their alloys Because of its low shear strength therefore lead acts as a solid lubricant Section 3211 and is smeared over the toolchip interface during cutting This behavior has been verified by the presence of high concentrations of lead on the toolside face of chips when machining leaded steels
When the temperature is sufficiently highfor instance at high cutting speeds and feeds Section 206the lead melts directly in front of the tool acting as a liquid lubricant In addition to this effect lead lowers the shear stress in the primary shear zone reducing cutting forces and power consumption Lead can be used in every grade of steel such as 10xx 11xx 12xx 41xx etc 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 resistance
However because lead is a wellknown 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 leadfree steels Bismuth and tin are now being investigated as possible substitutes for lead in steels
CalciumDeoxidized Steels An important development is calciumdeoxidized steels in which oxide flakes of calcium silicates CaSo are formed These flakes in turn reduce the strength of the secondary shear zone decreasing toolchip interface and wear Temperature is correspondingly reduced Consequently these steels produce less crater wear especially at high cutting speeds
Stainless Steels Austenitic 300 series steels are generally difficult to machine Chatter can be s problem necessitating machine tools with high stiffness However ferritic stainless steels also 300 series have good machinability Martensitic 400 series steels are abrasive tend to form a builtup edge and require tool materials with high hot hardness and craterwear resistance Precipitationhardening stainless steels are strong and abrasive requiring hard and abrasionresistant tool materials
The Effects of Other Elements in Steels on Machinability 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 abrasive These compounds increase tool wear and reduce machinability It is essential to produce and use clean steels
Carbon and manganese have various effects on the machinability of steels depending on their composition Plain lowcarbon steels less than 015 C can produce poor surface finish by forming a builtup edge Cast steels are more abrasive although their machinability is similar to that of wrought steels Tool and die steels are very difficult to machine and usually require annealing prior to machining Machinability of most steels is improved by cold working which hardens the material and reduces the tendency for builtup edge formation
Other alloying elements such as nickel chromium molybdenum and vanadium which improve the properties of steels generally reduce machinability The effect of boron is negligible Gaseous elements such as hydrogen and nitrogen can have particularly detrimental effects on the properties of steel 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 machinability
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 service At elevated temperatures for example lead causes embrittlement of steels liquidmetal embrittlement hot shortness see Section 143 although at room temperature it has no effect on mechanical properties
Sulfur can severely reduce the hot workability of steels because of the formation of iron sulfide unless sufficient manganese is present to prevent such formation 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 machinability
2092 Machinability of Various Other Metals
Aluminum is generally very easy to machine although the softer grades tend to form a builtup edge resulting in poor surface finish High cutting speeds high rake angles and high relief angles are recommended Wrought aluminum alloys with high silicon content and cast aluminum alloys may be abrasive they require harder tool materials Dimensional tolerance control may be a problem in machining aluminum since it has a high thermal coefficient of expansion and a relatively low elastic modulus
Beryllium is similar to cast irons Because it is more abrasive and toxic though it requires machining in a controlled environment
Cast gray irons are generally machinable but are Free carbides in castings reduce their machinability and cause tool chipping or fracture necessitating tools with high toughness Nodular and malleable irons are machinable with hard tool materials
Cobaltbased alloys are abrasive and highly workhardening They require sharp abrasionresistant tool materials and low feeds and speeds
Wrought copper can be difficult to machine because of builtup edge formation although cast copper alloys are easy to machine Brasses are easy to machine especially with the addition pf lead leaded freemachining brass Bronzes are more difficult to machine than brass
Magnesium is very easy to machine with good surface finish and prolonged tool life 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 workhardening so it can produce poor surface finish Sharp tools are necessary
Nickelbased alloys are workhardening abrasive and strong at high temperatures Their machinability is similar to that of stainless steels
Tantalum is very workhardening ductile and soft It produces a poor surface finish tool wear is high
Titanium and its alloys have poor thermal conductivity indeed the lowest of all metals causing significant temperature rise and builtup edge they can be difficult to machine
Tungsten is brittle strong and very abrasive so its machinability is low although it greatly improves at elevated temperatures
Zirconium has good machinability It requires a coolanttype cutting fluid however because of the explosion and fire
2093 Machinability of Various Materials
Graphite is abrasive it requires hard abrasionresistant sharp tools
Thermoplastics generally have low thermal conductivity low elastic modulus and low softening temperature 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 and
proper support of the workpiece Tools should be sharp
External cooling of the cutting zone may be necessary to keep the chips from becoming gummy and sticking to the tools Cooling can usually be achieved with a jet of air vapor mist or watersoluble oils Residual stresses may develop during machining To relieve these stresses machined parts can be annealed for a period of time at temperatures ranging from to to and then cooled slowly and uniformly to room temperature
Thermosetting plastics are brittle and sensitive to thermal gradients during cutting Their machinability is generally similar to that of thermoplastics
Because of the fibers present reinforced plastics are very abrasive and are difficult to machine Fiber tearing pulling and edge delamination are significant problems they can lead to severe reduction in the loadcarrying capacity of the component Furthermore machining of these materials requires careful removal of machining debris to avoid contact with and inhaling of the fibers
The machinability of ceramics has improved steadily with the development of nanoceramics Section 825 and with the selection of appropriate processing parameters such as ductileregime cutting Section 2242
Metalmatrix and ceramicmatrix composites can be difficult to machine depending on the properties of the individual components ie reinforcing or whiskers as well as the matrix material
2094 Thermally Assisted Machining
Metals and alloys that are difficult to machine at room temperature can be machined more easily at elevated temperatures In thermally assisted machining hot machining the source of heata torch induction coil highenergy beam such as laser or electron beam or plasma arcis forces b increased tool life c use of inexpensive cuttingtool materials d higher materialremoval rates and e reduced tendency for vibration and chatter
It may be difficult to heat and maintain a uniform temperature distribution within the workpiece Also the original microstructure of the workpiece may be adversely affected by elevated temperatures Most applications of hot machining are in the turning of highstrength metals and alloys although experiments are in progress to machine ceramics such as silicon nitrideSUMMARY
Machinability is usually defined in terms of surface finish tool life force and power requirements and chip control Machinability of materials depends not only on their intrinsic properties and microstructure but also on proper selection and control of process variables
译文
209 机加工性
种材料机加工性通常四种素方式定义
材料表面光洁性表面完整性
2刀具寿命
3切削力功率需求
4切屑控制
种方式机加工性指表面光洁性完整性长刀具寿命低切削力功率需求关切屑控制细长卷曲切屑果没切割成片切屑区变混乱缠起方式够严重介入剪切工序
剪切工序复杂属性难建立定量释义材料机加工性关系制造厂里刀具寿命表面粗糙度通常认机加工性中重素已量准确机加工率例子中够常
2091 钢机加工性
钢重工程材料(正第5章示)机加工性已广泛研究通添加铅硫磺钢机加工性已提高谓易切削钢
二次硫化钢二次磷化钢硫钢中形成硫化锰夹杂物(第二相粒子)夹杂物第剪切区引起应力结果切屑容易断开变改善加工性夹杂物形状分布集中程度显著影响材料加工性化学元素碲硒化学性质硫类似二次硫化钢中起夹杂物改性作
钢中磷两方面影响第影响加强铁素体增加硬度越硬钢形成更切屑形成更表面光洁性需注意软钢适合积屑瘤形成差表面光洁性机器第二影响增加钢硬度引起短切屑断细长切屑形成提高切削加工性
含铅钢钢中高含量铅硫化锰夹杂物尖端析出非二次硫化钢中铅呈细分散颗粒铅铁铜铝合金中溶解低抗剪强度铅充固体润滑剂切削时涂刀具切屑接口处特性已机加工铅钢时切屑刀具面表面高浓度铅存证实
温度足够高时例高切削速度进速度铅刀具前直接熔化充液体润滑剂种效应铅降低第剪切区中剪应力减切削力功率消耗铅种钢号例10XX11XX12XX41XX等等铅钢第二第三数码中字母L识(例10L45)(需注意锈钢中字母L相法指低碳提高耐蚀性条件)
然铅名毒素污染物钢中存着严重环境隐患(钢产品中年约4500吨铅消耗)结果估算钢中含铅量存持续趋势铋锡现正作钢中铅代物深入研究
脱氧钙钢重发展脱氧钙钢脱氧钙钢中矽酸钙盐中氧化物片形成薄片次减第二剪切区中力量降低刀具切屑接口处摩擦磨损温度相应降低结果钢产生更月牙洼磨损特高切削速度时更
锈钢奥氏体钢通常难机加工振动成问题需高硬度高强度机床然铁素体锈钢具良机加工性马氏体钢易磨蚀易形成积屑瘤求刀具材料高热硬度耐月牙洼磨损性沉淀硬化锈钢强度高磨蚀性强求刀具材料硬耐磨
钢中元素机加工性方面影响钢中铝硅存总害元素结合氧会生成氧化铝矽酸盐氧化铝硅酸盐硬具磨蚀性化合物增加刀具磨损降低机加工性生产净化钢非常必
根构成碳锰钢钢机加工性方面影响低碳素钢(少015碳)通形成积屑瘤生成差表面光洁性铸钢机加工性锻钢致相铸钢具更磨蚀性刀具模具钢难机加工通常煅烧机加工数钢机加工性冷加工提高冷加工材料变硬减少积屑瘤形成
合金元素例镍铬钳钒提高钢特性减机加工性硼影响忽视气态元素氢氮钢特性方面特害影响氧已证明硫化锰夹杂物横方面强影响越高含氧量产生越低横越高机加工性
选择种元素改善加工性应该考虑元素已加工零件中性强度利影响例温度升高时铝会钢变脆(液体金属脆化热脆化见143节)室温力学性没影响
硫化铁构成硫严重减少钢热加工性非足够锰防止种结构形成室温二次磷化钢机械性赖变形硫化锰夹杂物定位(异性)二次磷化钢具更延展性单独生成提高机加工性
2092 金属机加工性
铝通常容易机加工越软品种易生成积屑瘤造成差表面光洁性高切削速度高前角高角推荐高含量矽锻铝合金铸铝合金许具磨蚀性求更硬刀具材料尺寸公差控制许机加工铝时会成问题高热膨胀系数相低弹性模数
铍类似铸铁更具磨蚀性毒性求控工环境进行机加工
灰铸铁普遍加工磨蚀性铸造中游离碳化物降低机加工性引起刀具切屑裂口需具强韧性工具具坚硬刀具材料球墨铸铁韧性铁加工
钴基合金磨蚀性高度加工硬化求锋利具耐蚀性刀具材料低进刀速度
铸铜合金容易机加工锻铜积屑瘤形成锻铜难机加工黄铜容易机加工特添加铅更容易青铜黄铜更难机加工
镁容易机加工镁表面光洁性长久刀具寿命然高氧化速度火灾危险(种元素易燃)应该特心
钳易拉长加工硬化生成差表面光洁性尖刀具必
镍基合金加工硬化具磨蚀性高温非常坚硬机加工性锈钢相
钽非常加工硬化具延性柔软生成高表面光洁性刀具磨损非常
钛合金导热性确金属中低引起明显温度升高积屑瘤难机加工
钨易脆坚硬具磨蚀性性高温提高机加工性低
锆机加工性然爆炸火种危险性求冷性质切削液
2093 种材料机加工性
石墨具磨蚀性求硬尖具耐蚀性刀具
塑性塑料通常低导热系数低弹性模量低软化温度机加工热塑性塑料求正前角刀具(降低切削力)求角切削走刀深相高速度工件正确支承刀具应该尖
切削区外部冷许必防止切屑变黏性粘刀具空气流汽雾水溶性油通常实现冷机加工时残余应力许生成发展解力已机加工部分()温度范围冷段时间然慢慢变化冷室温
热固性塑料易脆切削时热梯度敏感机加工性热塑性塑料相
纤维存加强塑料具磨蚀性难机加工纤维撕裂拉出边界分层非常严重问题导致构成素承载力降材料机加工求加工残片仔细切避免接触吸进纤维
着纳米陶瓷(见825节)发展适参数处理选择例塑性切削(见2242节)陶瓷器机加工性已提高
金属基复合材料陶瓷基复合材料机加工赖单独成分特性说增强纤维金属须基体材料
2094 热辅助加工
室温难机加工金属合金高温更容易机加工热辅助加工时(高温切削)热源火感应线圈高束流(例雷射电子束)等离子弧集中切削刀具前块区域处(a)低切削力(b)增加刀具寿命(c)便宜切削刀具材料(d)更高材料切率(e)减少振动
许难工件加热保持变温度分布工件初微观结构许高温影响种影响相害实验进行中机加工陶瓷器氮化矽高温切削数应高强度金属高温度合金车削中
总结
通常零件机加工性根素定义表面粗糙度刀具寿命切削力功率需求切屑控制材料机加工性仅取决起特性微观结构赖工艺参数合理选择控制
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