內(nèi)燃機后油封蓋機械加工工藝規(guī)程設(shè)計及系列夾具設(shè)計【車內(nèi)外圓】【銑底平面】【鉆φ8.5和φ9孔】【說明書+CAD+SOLIDWORKS】

購買設(shè)計請充值后下載，資源目錄下的文件所見即所得，都可以點開預(yù)覽，資料完整，充值下載可得到資源目錄里的所有文件?！咀ⅰ浚篸wg后綴為CAD圖紙，doc,docx為WORD文檔，原稿無水印，可編輯。具體請見文件預(yù)覽，有不明白之處，可咨詢QQ:12401814 編號無錫太湖學(xué)院畢業(yè)設(shè)計（論文）相關(guān)資料題目：內(nèi)燃機后油封蓋機械加工工藝規(guī)程設(shè)計及系列夾具設(shè)計 信機 系 機械工程及自動化專業(yè)學(xué) 號： 0923169 學(xué)生姓名： 何巍巍 指導(dǎo)教師： 張大駿（職稱：高級工程師） （職稱： ）2013年5月25日目 錄一、畢業(yè)設(shè)計（論文）開題報告二、畢業(yè)設(shè)計（論文）外文資料翻譯及原文三、學(xué)生“畢業(yè)論文（論文）計劃、進度、檢查及落實表”四、實習(xí)鑒定表無錫太湖學(xué)院畢業(yè)設(shè)計（論文）開題報告題目：內(nèi)燃機后油封蓋機械加工工藝規(guī)程設(shè)計及系列夾具設(shè)計 信機 系 機械工程及自動化 專業(yè)學(xué) 號： 0923169 學(xué)生姓名： 何巍巍 指導(dǎo)教師： 張大駿（職稱：高級工程師 ） （職稱： ）2012年11月25日 課題來源本課題是廣西玉林柴油機廠提供圖紙委托無錫市宏業(yè)機電配件廠加工的柴油機零件，無錫市宏業(yè)機電配件廠提供相關(guān)資料,此種柴油機在載重汽車及客車上廣泛使用?？茖W(xué)依據(jù)（包括課題的科學(xué)意義；國內(nèi)外研究概況、水平和發(fā)展趨勢；應(yīng)用前景等）1、工藝是機械產(chǎn)品設(shè)計制造過程中十分重要的一個環(huán)節(jié)，其水平與質(zhì)量直接影響到產(chǎn)品的最終制造質(zhì)量及成本運行。2、加工技術(shù)正向高度信息化、自動化、智能化的方向發(fā)展，各種現(xiàn)代的加工方法也不斷地創(chuàng)造和完善，如快速成型技術(shù)、激光加工、電加工和射流加工等已相當(dāng)廣泛的應(yīng)用到加工中去，而這些使工藝設(shè)計也帶來巨大的進步。3、作為機械專業(yè)的本科畢業(yè)生采用此類課題可以培養(yǎng)學(xué)生認(rèn)識機械加工生產(chǎn)準(zhǔn)備工作是怎樣一個過程，可以受到理論與實踐相結(jié)合的鍛煉。研究內(nèi)容1、機械加工工藝規(guī)程的編制，結(jié)合具體工廠的條件和發(fā)展前景進行考慮。2、同樣結(jié)合具體工廠的現(xiàn)有生產(chǎn)條件和發(fā)展前景設(shè)計專用（不少于三副）擬采取的研究方法、技術(shù)路線、實驗方案及可行性分析采用組織分析零件的具體結(jié)構(gòu)，加工精度要求，表面粗糙度要求，制定出初步的加工方案，然后組織學(xué)生下工廠參觀、實習(xí)、實地了解工廠出現(xiàn)的生產(chǎn)條件，發(fā)展展望及具體的生產(chǎn)水平。然后在此基礎(chǔ)上編制工藝規(guī)程，填寫工藝文件，設(shè)計專用夾具，待初步完成后，再回工廠征集意見，加以改進，定稿。研究計劃及預(yù)期成果研究計劃：2012年11月12日-2012年12月2日：按照任務(wù)書要求查閱論文相關(guān)參考資料，填寫畢業(yè)設(shè)計開題報告書。2012年12月3日-2013年3月1日：參加實訓(xùn)及填寫畢業(yè)實習(xí)報告。2013年3月4日-2013年3月8日：學(xué)習(xí)并翻譯一篇與畢業(yè)設(shè)計相關(guān)的英文材料。2013年3月11日-2013年3月22日：工藝路線及夾具方案的確定。2013年3月25日-2013年4月12日：夾具圖及Solidworks模組圖的繪制。2013年4月15日-2013年4月19日：工藝規(guī)程設(shè)計和工藝過程卡、工序卡設(shè)計。2013年4月22日-2013年5月10日：工藝計算和夾具設(shè)計。2013年5月13日-2013年5月25日：畢業(yè)論文撰寫和修改工作。預(yù)期成果：工藝規(guī)程、工藝卡片、工序卡片夾具總圖及主要的零件圖、Solidworks模組圖設(shè)計說明書、相關(guān)資料特色或創(chuàng)新之處工藝規(guī)程可以適用于一般中小型工廠的普通通用機床，也能改進后用于專用機床，或加工中心，適用于范圍較廣。已具備的條件和尚需解決的問題現(xiàn)有廣西玉柴機器集團有限公司生產(chǎn)內(nèi)燃機后油封蓋的零件圖樣，委托加工工廠的現(xiàn)有生產(chǎn)條件及技術(shù)狀況，特別是已有的生產(chǎn)經(jīng)驗。目前缺少設(shè)計手冊、資料等，對檢測條件也不夠清楚其它資料也缺乏。指導(dǎo)教師意見該生已查閱大量國內(nèi)外參考資料,已對課題有了一定了解,計劃詳細可行,同意開題。 指導(dǎo)教師簽名：2012年 11月 25日教研室（學(xué)科組、研究所）意見教研室主任簽名： 年 月 日系意見主管領(lǐng)導(dǎo)簽名： 年 月 日無錫太湖學(xué)院畢業(yè)設(shè)計（論文）外文資料翻譯 信機 系 機械工程及自動化 專業(yè)院 （系）： 信 機 系 專 業(yè)： 機械工程及自動化 班 級： 機械94班 姓 名： 何巍巍 學(xué) 號： 0923169 外文出處： Manufacturing Engineering and TechnologyMachining 附 件： 1.譯文；2.原文；3.評分表 2013年5月25日 英文原文MACHINABILITYThe machinability of a material usually defined in terms of four factors:1、 Surface finish and integrity of the machined part;2、 Tool life obtained;3、 Force and power requirements;4、 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.Machinability Of SteelsBecause steels are among the most important engineering materials, their machinability has been studied extensively. The machinability of steels has been mainly improved by adding lead and sulfur to obtain so-called free-machining steels.Resulfurized and Rephosphorized steels. Sulfur in steels forms manganese sulfide inclusions (second-phase 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 built-up 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 non-resulfurized 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 32.11) and is smeared over the tool-chip interface during cutting. This behavior has been verified by the presence of high concentrations of lead on the tool-side face of chips when machining leaded steels.When the temperature is sufficiently high-for instance, at high cutting speeds and feeds (Section 20.6)the 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 “l(fā)ow carbon,” a condition that improves their corrosion resistance.)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 steels.Calcium-Deoxidized Steels. An important development is calcium-deoxidized steels, in which oxide flakes of calcium silicates (CaSo) are formed. These flakes, in turn, reduce the strength of the secondary shear zone, decreasing tool-chip 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 built-up edge, and require tool materials with high hot hardness and crater-wear resistance. Precipitation-hardening stainless steels are strong and abrasive, requiring hard and abrasion-resistant 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 low-carbon steels (less than 0.15% C) can produce poor surface finish by forming a built-up 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 built-up 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 (liquid-metal embrittlement, hot shortness), 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.Machinability of Various Other Metals Aluminum is generally very easy to machine, although the softer grades tend to form a built-up 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.Cobalt-based alloys are abrasive and highly work-hardening. They require sharp, abrasion-resistant tool materials and low feeds and speeds.Wrought copper can be difficult to machine because of built-up edge formation, although cast copper alloys are easy to machine. Brasses are easy to machine, especially with the addition pf lead (leaded free-machining 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 work-hardening, so it can produce poor surface finish. Sharp tools are necessary.Nickel-based alloys are work-hardening, abrasive, and strong at high temperatures. Their machinability is similar to that of stainless steels.Tantalum is very work-hardening, 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 built-up 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 coolant-type cutting fluid, however, because of the explosion and fire.Machinability of Various MaterialsGraphite is abrasive; it requires hard, abrasion-resistant, 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 water-soluble 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 load-carrying 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 and with the selection of appropriate processing parameters, such as ductile-regime cutting.Metal-matrix and ceramic-matrix composites can be difficult to machine, depending on the properties of the individual components, i.e., reinforcing or whiskers, as well as the matrix material.Thermally Assisted MachiningMetals 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, high-energy beam (such as laser or electron beam), or plasma arcis forces, (b) increased tool life, (c) use of inexpensive cutting-tool materials, (d) higher material-removal 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 high-strength metals and alloys, although experiments are in progress to machine ceramics such as silicon nitride. SUMMARYMachinability 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.中文譯文可機加工性一種材料的可機加工性通常以四種因素的方式定義：1、 分的表面光潔性和表面完整性。2、刀具的壽命。3、切削力和功率的需求。4、切屑控制。以這種方式，好的可機加工性指的是好的表面光潔性和完整性，長的刀具壽命，低的切削力和功率需求。關(guān)于切屑控制，細長的卷曲切屑，如果沒有被切割成小片，以在切屑區(qū)變的混亂，纏在一起的方式能夠嚴(yán)重的介入剪切工序。因為剪切工序的復(fù)雜屬性，所以很難建立定量地釋義材料的可機加工性的關(guān)系。在制造廠里，刀具壽命和表面粗糙度通常被認(rèn)為是可機加工性中最重要的因素。盡管已不再大量的被使用，近乎準(zhǔn)確的機加工率在以下的例子中能夠被看到。鋼的可機加工性因為鋼是最重要的工程材料之一，所以他們的可機加工性已經(jīng)被廣泛地研究過。通過宗教鉛和硫磺，鋼的可機加工性已經(jīng)大大地提高了。從而得到了所謂的易切削鋼。二次硫化鋼和二次磷化鋼 硫在鋼中形成硫化錳夾雜物（第二相粒子），這些夾雜物在第一剪切區(qū)引起應(yīng)力。其結(jié)果是使切屑容易斷開而變小，從而改善了可加工性。這些夾雜物的大小、形狀、分布和集中程度顯著的影響可加工性?；瘜W(xué)元素如碲和硒，其化學(xué)性質(zhì)與硫類似，在二次硫化鋼中起夾雜物改性作用。鋼中的磷有兩個主要的影響。它加強鐵素體，增加硬度。越硬的鋼，形成更好的切屑形成和表面光潔性。需要注意的是軟鋼不適合用于有積屑瘤形成和很差的表面光潔性的機器。第二個影響是增加的硬度引起短切屑而不是不斷的細長的切屑的形成，因此提高可加工性。含鉛的鋼 鋼中高含量的鉛在硫化錳夾雜物尖端析出。在非二次硫化鋼中，鉛呈細小而分散的顆粒。鉛在鐵、銅、鋁和它們的合金中是不能溶解的。因為它的低抗剪強度。因此，鉛充當(dāng)固體潤滑劑并且在切削時，被涂在刀具和切屑的接口處。這一特性已經(jīng)被在機加工鉛鋼時，在切屑的刀具面表面有高濃度的鉛的存在所證實。當(dāng)溫度足夠高時例如，在高的切削速度和進刀速度下鉛在刀具前直接熔化，并且充當(dāng)液體潤滑劑。除了這個作用，鉛降低第一剪切區(qū)中的剪應(yīng)力，減小切削力和功率消耗。鉛能用于各種鋼號，例如10XX，11XX，12XX，41XX等等。鉛鋼被第二和第三數(shù)碼中的字母L所識別（例如，10L45）。（需要注意的是在不銹鋼中，字母L的相同用法指的是低碳，提高它們的耐蝕性的條件）。然而，因為鉛是有名的毒素和污染物，因此在鋼的使用中存在著嚴(yán)重的環(huán)境隱患（在鋼產(chǎn)品中每年大約有4500噸的鉛消耗）。結(jié)果，對于估算鋼中含鉛量的使用存在一個持續(xù)的趨勢。鉍和錫現(xiàn)正作為鋼中的鉛最可能的替代物而被人們所研究。脫氧鈣鋼 一個重要的發(fā)展是脫氧鈣鋼，在脫氧鈣鋼中矽酸鈣鹽中的氧化物片的形成。這些片狀，依次減小第二剪切區(qū)中的力量，降低刀具和切屑接口處的摩擦和磨損。溫度也相應(yīng)地降低。結(jié)果，這些鋼產(chǎn)生更小的月牙洼磨損，特別是在高切削速度時更是如此。不銹鋼 奧氏體鋼通常很難機加工。振動能成為一個問題，需要有高硬度的機床。然而，鐵素體不銹鋼有很好的可機加工性。馬氏體鋼易磨蝕，易于形成積屑瘤，并且要求刀具材料有高的熱硬度和耐月牙洼磨損性。經(jīng)沉淀硬化的不銹鋼強度高、磨蝕性強，因此要求刀具材料硬而耐磨。鋼中其它元素在可機加工性方面的影響 鋼中鋁和矽的存在總是有害的，因為這些元素結(jié)合氧會生成氧化鋁和矽酸鹽，而氧化鋁和矽酸鹽硬且具有磨蝕性。這些化合物增加刀具磨損，降低可機加工性。因此生產(chǎn)和使用凈化鋼非常必要。根據(jù)它們的構(gòu)成，碳和錳鋼在鋼的可機加工性方面有不同的影響。低碳素鋼（少于0.15%的碳）通過形成一個積屑瘤能生成很差的表面光潔性。盡管鑄鋼的可機加工性和鍛鋼的大致相同，但鑄鋼具有更大的磨蝕性。刀具和模具鋼很難用于機加工，他們通常再煅燒后再機加工。大多數(shù)鋼的可機加工性在冷加工后都有所提高，冷加工能使材料變硬并且減少積屑瘤的形成。其它合金元素，例如鎳、鉻、鉗和釩，能提高鋼的特性，減小可機加工性。硼的影響可以忽視。氣態(tài)元素比如氫和氮在鋼的特性方面能有特別的有害影響。氧已經(jīng)被證明了在硫化錳夾雜物的縱橫比方面有很強的影響。越高的含氧量，就產(chǎn)生越低的縱橫比和越高的可機加工性。選擇各種元素以改善可加工性，我們應(yīng)該考慮到這些元素對已加工零件在使用中的性能和強度的不利影響。例如，當(dāng)溫度升高時，鋁會使鋼變脆（液體金屬脆化，熱脆化），盡管其在室溫下對力學(xué)性能沒有影響。因為硫化鐵的構(gòu)成，硫能嚴(yán)重的減少鋼的熱加工性，除非有足夠的錳來防止這種結(jié)構(gòu)的形成。在室溫下，二次磷化鋼的機械性能依賴于變形的硫化錳夾雜物的定位（各向異性）。二次磷化鋼具有更小的延展性，被單獨生成來提高機加工性。其它不同金屬的機加工性盡管越軟的品種易于生成積屑瘤，但鋁通常很容易被機加工，導(dǎo)致了很差的表面光潔性。高的切削速度，高的前角和高的后角都被推薦了。有高含量的矽的鍛鋁合金鑄鋁合金也許具有磨蝕性，它們要求更硬的刀具材料。尺寸公差控制也許在機加工鋁時會成為一個問題，因為它有膨脹的高導(dǎo)熱系數(shù)和相對低的彈性模數(shù)。鋁的重量輕和耐腐蝕，是其性能的兩大突出特點。純鋁的密度約為2.7g/cm3,僅為鐵、銅密度的三分之一。無論是固體鋁或熔融鋁，其密度均隨著純度的提高而降低；同等純度的熔融鋁的密度，則隨溫度的提高而降低。鋁對自然界的水（含海水）、大氣中的各種元素，以及油料與各種化學(xué)物品，都良好的耐蝕性。這是由于鋁的化學(xué)性質(zhì)及其活潑，其最特殊的性能是具有同氧（特別是空氣中的氧）強烈結(jié)合的傾向，鋁在空氣中被其表面生成一層厚度約為2x10-4mm的致密氧化膜（三氧化二鋁）所覆蓋，防止了鋁的繼續(xù)氧化，從而使鋁具有良好的耐蝕性。鋁合金能承受壓力加工?？杉庸こ筛鞣N形態(tài)、規(guī)格的鋁合金材。主要用于制造航空器材、建筑用門窗等。 形變鋁合金又分為不可熱處理強化型鋁合金和可熱處理強化型鋁合金。不可熱處理強化型不能通過熱處理來提高機械性能，只能通過冷加工變形來實現(xiàn)強化，它主要包括高純鋁、工業(yè)高純鋁、工業(yè)純鋁以及防銹鋁等?？蔁崽幚韽娀弯X合金可以通過淬火和時效等熱處理手段來提高機械性能，它可分為硬鋁、鍛鋁、超硬鋁和特殊鋁合金等。純鋁的力學(xué)性能不高，不適宜制作承受較大載荷的結(jié)構(gòu)零件。為了提高鋁的力學(xué)性能在純鋁中加入某些合金元素制成合金，常加入的合金元素有銅、鎂、鉻、鋅、硅、錳、鎳、鈷、鈦及鍶等，稀土元素在某些合金中加入。這些合金元素加入后通過以下幾個方面對鋁進行強化。鋁合金熱處理后可以得到過飽和的鋁基固溶體。這種過飽和鋁基固溶體在室溫或加熱到某一溫度時，其強度和硬度隨時間和延長而增高，但塑性降低。這個過程就稱時效。時效過程中使合金的強度、硬度增高的現(xiàn)象稱為時效強化或時效硬化。當(dāng)鋁中加入的合金元素含水量超過其極限溶解度時，淬火加熱時便有一部分不能溶入固溶體的第二相出現(xiàn)稱之為過剩相。在鋁合金中過剩相多為硬而脆的金屬間化合物。它們在合金中起阻礙滑移和位錯運動的作用，使強度、硬度提高，而塑性、韌性降低。合金中過剩相的數(shù)量愈多，其強化效果愈好，但過剩相多時，由于合金變脆而導(dǎo)致強度、塑性降低。在鋁合中添加微量元素細化組織是提高鋁合金力學(xué)性能的另一種重要手段。變形鋁合金中添加微量鈦、鋯、鈹、鍶以及稀土元素，它們能形成難熔化合物，在合金結(jié)晶時作為非自發(fā)晶核，起細化晶粒作用，提高合金的強度和塑性。鑄造鋁合金中常加入微量元素作變質(zhì)處理來細化合金組織，提高強度和塑性。變質(zhì)處理對不能熱處理強化或強化效果不大的鑄造鋁合金和變形鋁合金具有特別重要的意義。比如在鋁硅鑄造鋁合金中加入微量鈉或鈉鹽或銻作變質(zhì)劑進行變質(zhì)處理，細化組織可以顯著提高塑性和強度。同樣在鑄造鋁合金中加入少量錳、鉻、鈷等元素能使雜質(zhì)鐵形成的板塊狀或針狀化合物AlFeSi細化，提高塑性，加入微量鍶可消除或減少初晶硅，并使共晶硅細化；粒子園整度提高。冷變形強化亦稱冷作硬化，即金屬材料在再結(jié)晶溫度以下冷變形，冷變形時，金屬內(nèi)部位錯密度增大，且相互纏結(jié)并形成胞狀結(jié)構(gòu)，阻礙位錯運動。變形度越大位錯纏結(jié)越嚴(yán)重，變形抗力越大，強度越高。冷變形后強化的程度隨變形度、變形溫度及材料本身的性質(zhì)而不同。同一材料在同一溫度下冷變形時，變形度越大則強度越高。塑性隨變形程度的增加而降低。壓力鑄造簡稱壓鑄，是一種將熔融合金液倒入壓室內(nèi)，以高速充填鋼制模具的型腔，并使合金液在壓力下凝固而形成鑄件的鑄造方法。壓鑄區(qū)別于其它鑄造方法的主要特點是高壓和高速。（1）金屬液是在壓力下填充型腔的，并在更高的壓力下結(jié)晶凝固，常見的壓力為15100MPa。（2）金屬液以高速充填型腔，通常在1050米/秒，有的還可超過80米/秒，（通過內(nèi)澆口導(dǎo)入型腔的線速度內(nèi)澆口速度），因此金屬液的充型時間極短，約0.010.2秒（須視鑄件的大小而不同）內(nèi)即可填滿型腔。壓鑄機、壓鑄合金與壓鑄模具是壓鑄生產(chǎn)的三大要素，缺一不可。所謂壓鑄工藝就是將這三大要素有機地加以綜合運用，使能穩(wěn)定地有節(jié)奏地和高效地生產(chǎn)出外觀、內(nèi)在質(zhì)量好的、尺寸符合圖樣或協(xié)議規(guī)定要求的合格鑄件，甚至優(yōu)質(zhì)鑄件。壓鑄的流動性流動性是指合金液體充填鑄型的能力。流動性的大小決定合金能否鑄造復(fù)雜的鑄件。在鋁合金中共晶合金的流動性最好。影響流動性的因素很多，主要是成分、溫度以及合金液體中存在金屬氧化物、金屬化合物及其他污染物的固相顆粒，但外在的根本因素為澆注溫度及澆注壓力（俗稱澆注壓頭）的高低。實際生產(chǎn)中，在合金已確定的情況下，除了強化熔煉工藝（精煉與除渣）外，還必須改善鑄型工藝性（砂模透氣性、金屬型模具排氣及溫度），并在不影響鑄件質(zhì)量的前提下提高澆注溫度，保證合金的流動性。鈹和鑄鐵相同。因為它更具磨蝕性和毒性，盡管它要求在可控人工環(huán)境下進行機加工。灰鑄鐵普遍地可加工，但也有磨蝕性。鑄造無中的游離碳化物降低它們的可機加工性，引起刀具切屑或裂口。它需要具有強韌性的工具。具有堅硬的刀具材料的球墨鑄鐵和韌性鐵是可加工的。鈷基合金有磨蝕性且高度加工硬化的。它們要求尖的且具有耐蝕性的刀具材料并且有低的走刀和速度。盡管鑄銅合金很容易機加工，但因為鍛銅的積屑瘤形成因而鍛銅很難機加工。黃銅很容易機加工，特別是有添加的鉛更容易。青銅比黃銅更難機加工。鎂很容易機加工，鎂既有很好的表面光潔性和長久的刀具壽命。然而，因為高的氧化速度和火種的危險（這種元素易燃），因此我們應(yīng)該特別小心使用它。鉗易拉長且加工硬化，因此它生成很差的表面光潔性。尖的刀具是很必要的。鎳基合金加工硬化，具有磨蝕性，且在高溫下非常堅硬。它的可機加工性和不銹鋼相同。鉭非常的加工硬化，具有可延性且柔軟。它生成很差的表面光潔性且刀具磨損非常大。鈦和它的合金導(dǎo)熱性(的確，是所有金屬中最低的)，因此引起明顯的溫度升高和積屑瘤。它們是難機加工的。鎢易脆，堅硬，且具有磨蝕性，因此盡管它的性能在高溫下能大大提高，但它的機加工性仍很低。鋯有很好的機加工性。然而，因為有爆炸和火種的危險性，它要求有一個冷卻性質(zhì)好的切削液。各種材料的機加工性石墨具有磨蝕性。它要求硬的、尖的，具有耐蝕性的刀具。塑性塑料通常有低的導(dǎo)熱性，低的彈性模數(shù)和低的軟化溫度。因此，機加工熱塑性塑料要求有正前角的刀具（以此降低切削力），還要求有大的后角，小的切削和走刀深的，相對高的速度和工件的正確支承。刀具應(yīng)該很尖。切削區(qū)的外部冷卻也許很必要，以此來防止切屑變的有黏性且粘在刀具上。有了空氣流，汽霧或水溶性油，通常就能實現(xiàn)冷卻。在機加工時，殘余應(yīng)力也許能生成并發(fā)展。為了解除這些力，已機加工的部分要在（）的溫度范圍內(nèi)冷卻一段時間，然而慢慢地?zé)o變化地冷卻到室溫。熱固性塑料易脆，并且在切削時對熱梯度很敏感。它的機加工性和熱塑性塑料的相同。因為纖維的存在，加強塑料具有磨蝕性，且很難機加工。纖維的撕裂、拉出和邊界分層是非常嚴(yán)重的問題。它們能導(dǎo)致構(gòu)成要素的承載能力大大下降。而且，這些材料的機加工要求對加工殘片仔細切除，以此來避免接觸和吸進纖維。隨著納米陶瓷的發(fā)展和適當(dāng)?shù)膮?shù)處理的選擇，例如塑性切削，陶瓷器的可機加工性已大大地提高了。金屬基復(fù)合材料和陶瓷基復(fù)合材料很能機加工，它們依賴于單獨的成分的特性，比如說增強纖維或金屬須和基體材料。熱輔助加工在室溫下很難機加工的金屬和合金在高溫下能更容易地機加工。在熱輔助加工時（高溫切削），熱源一個火把，感應(yīng)線圈，高能束流（例如雷射或電子束），或等離子弧被集中在切削刀具前的一塊區(qū)域內(nèi)。好處是：（a）低的切削力。（b）增加的刀具壽命。（c）便宜的切削刀具材料的使用。（d）更高的材料切