變速器箱體機械加工工藝及夾具設計,變速器,箱體,機械,加工,工藝,夾具,設計 密 級 分類號 編 號 成 績 本科生畢業(yè)設計 (論文) 外 文 翻 譯 原 文 標 題 Precision Machining Technology 譯 文 標 題 精密機械加工工藝 作者所在系別 作者所在專業(yè) 作者所在班級 作 者 姓 名 作 者 學 號 指導教師姓名 指導教師職稱 完 成 時 間 譯文標題 精密機械加工工藝 原文標題 Precision Machining Technology 作 者 Peter J. Hoffman 譯 名 彼得·J·霍夫 曼 國 籍 美國 原文出處 Cengage Learning 譯文： 精密機械加工工藝 在機械加工過程中，工件受到切削力、離心力、慣性力等作用，為了保證在這些外力作用下，工件仍能在夾具中保持已由定位元件確定的加工位置，而不致發(fā)生振動或位移、夾具結(jié)構中應設置夾緊裝置將工件可靠夾牢。 一、夾緊裝置的組成 夾緊裝置的種類很多，但其結(jié)構均由兩部分組成。 1． 動力裝置 夾緊力的來源，一是人力；二是某種裝置所產(chǎn)生的力。能產(chǎn)生力的裝置稱為夾具的動力裝置。常用的動力裝置有：氣動裝置、液壓裝置、電動裝置、電磁裝置、氣—液聯(lián)動裝置和真空裝置等。由于手動夾具的夾緊力來自人力，所以它沒有動力裝置。 2． 夾緊部分 接受和傳遞原始作用力使之變?yōu)閵A緊力并執(zhí)行夾緊任務的部分，一般由下列機構組成： 1）接受原始作用力的機構。如手柄、螺母及用來連接氣缸活塞桿的機構等。 2）中間遞力機構。如鉸鏈、杠桿等。 3）夾緊元件。如各種螺釘壓板等。 其中中間遞力機構在傳遞原始作用力至夾緊元件的過程中可以起到諸如改變作用力的方向、改變作用力的大小以及自鎖等作用。 二、夾緊裝置的基本要求 在不破壞工件定位精度，并保證加工質(zhì)量的前提下，應盡量使夾緊裝置做到： 1. 夾緊力的大小適當。既要保證工件在整個加工過程中其位置穩(wěn)定不變、振動小，又要使工件不產(chǎn)生過大的夾緊變形。 2. 工藝性好。夾緊裝置的復雜程度應與生產(chǎn)綱領相適應，在保證生產(chǎn)效率的前提下，其結(jié)構應力求簡單，便于制造和維修。 3. 使用性好。夾緊裝置的操作應當方便、安全、省力。 三、基本夾緊機構 原始作用力轉(zhuǎn)化為夾緊力是通過夾緊機構來實現(xiàn)的。在眾多的夾緊機構中以斜楔、螺旋、偏心以及由它們組合而成的夾緊機構應用最為普遍。 1. 斜楔夾緊機構 采用斜楔作為傳力元件或夾緊元件的夾緊機構稱為斜楔夾緊機構。 直接采用斜楔夾緊時，斜楔的自鎖條件是：斜楔的升角小于斜楔與工件、斜 楔與夾具體之間的摩擦角之和.即： α≤Φ1+Φ2 為保證自鎖可靠，手動夾緊機構一般取α=6°~8°。用氣壓或液壓裝置驅(qū)動的斜楔不需要自鎖，可取 a =15 ° ~35 °。 斜楔夾緊具有結(jié)構簡單，增力比大，自鎖性能好等特點，因此獲得廣泛應用。 （二）螺旋夾緊機構 采用螺桿作中間傳力元件的夾緊機構統(tǒng)稱為螺旋夾緊機構。由于它結(jié)構簡單、夾緊可靠、通用性好，而且由于螺旋升角小，螺旋夾緊機構的自鎖性能好，夾緊力和夾緊行程都較大，是手動夾具上用得最多的一種夾緊機構。 1. 簡單螺旋夾緊機構 最簡單的螺旋夾緊機構由于直接用螺釘頭部壓緊工件，易使工件受壓表面損傷，或帶動工件旋轉(zhuǎn)。因此常在頭部裝有擺動的壓塊。由于壓塊與工件間的摩擦力矩大于壓塊與螺釘間的摩擦力矩，壓塊不會隨螺釘一起轉(zhuǎn)動。夾緊動作慢、工件裝卸費時是單個螺旋夾緊機構的另一個缺點。為克服這一缺點，可采用快速夾緊機構。 2. 螺旋壓板夾緊機構 在夾緊機構中，螺旋壓板的使用非常普遍，常見的螺旋壓板典型結(jié)構其結(jié)構尺寸均已標準化，設計者可參考有關國家標準和夾具設計手冊進行設計。 2. 偏心夾緊機構 用偏心件直接或間接夾緊工件的機構，稱為偏心夾緊機構。偏心件有兩種形式，即圓偏心和曲線偏心，其中，圓偏心機構因結(jié)構簡單、制造容易而得到廣泛應用。 偏心夾緊加工操作方便、夾緊迅速，缺點是夾緊力和夾緊行程都小。一般用于切削力不大、振動小、沒有離心力影響的加工中。 1．圓偏心輪的工作原理 2．圓偏心輪的夾緊行程及工作段 3.偏心輪的自鎖條件 αmax≤Φ1+Φ2 推導得： f1≥ 2e／D 當 f= 0.1 時，e／D ≥20 當 f= 0.15 時，e／D ≥14 四、定心夾緊機構 當工件被加工面以中心要素（軸線、中心平面等）為工序基準時，為使基準重合以減少定位誤差，需采用定心夾緊機構。 定心夾緊機構具有定心和夾緊兩種功能，如臥式車床的三爪自定心卡盤即為最常用的典型實例。 定心夾緊機構按其定心作用原理有兩種類型，一種是依靠傳動機構使定心夾緊元件等速移動，從而實現(xiàn)定心夾緊，如螺旋式、杠桿式、楔式機構等；另一種是利用薄壁彈性元件受力后產(chǎn)生均勻的彈性變形（收縮或擴張） ，來實現(xiàn)定心夾緊，如彈簧筒夾、膜片卡盤、波紋套、液性塑料等。 1. 螺旋式定心夾緊機構 螺桿兩端的螺紋旋向相反，螺距相同。當其旋轉(zhuǎn)時，使兩個 V 形鉗口作對向等速移動，從而實現(xiàn)對工件的定心夾緊或松開。V 形鉗口可按工件不同形狀進行更換。 這種定心夾緊機構的特點是：結(jié)構簡單、工作行程大、通用性好，但定心精度不高，主要適用于粗加工或半精加工中需要行程大而定心精度要求不高的場合。 2. 杠桿式定心夾緊機構 杠桿式三爪自定心卡盤中，滑套作軸向移動時，圓周均布的三個鉤形杠桿便繞軸轉(zhuǎn)動， 撥動三個滑塊沿徑向移動，從而帶動其上卡爪將工件定心并夾緊或松開。 這種定心夾緊機構具有剛性大、動作快、增力倍數(shù)大、工作行程也比較大等特點，但其定心精度較低。一般為 0.1mm 左右，它主要用于工件的粗加工。由于杠桿機構不能自鎖，所以這種機構自鎖要靠氣壓或其它機構。 3. 楔式定心夾緊機構 機動的楔式夾爪自動定心機構中，當工件以內(nèi)孔及左端面在夾具上定位后，汽缸通過拉桿使六個夾爪左移， 由于本體上斜面的作用，夾爪左移的同時向外脹開，將工件定心夾緊；反之，夾爪右移時，在彈簧卡圈的作用下使夾爪收攏，將工件松開。 這種定心夾緊機構的結(jié)構緊湊，定心精度一般可達 0.02mm0.07mm，比較適用于工件內(nèi)孔作定位基面的半精加工工序。 4. 彈簧筒夾式定心夾緊機構 這種定心夾緊機構常用于安裝軸套類工件。 彈性定心夾緊機構的結(jié)構簡單、體積小、操作方便迅速，因而應用十分廣泛。其定心精度可穩(wěn)定在 0.04mm0.010mm 之間。除上述介紹的定心夾緊機構外，常用的還有膜片卡盤機構、波紋套定心夾緊機構以及液性塑料夾緊機構等。 夾具是機械加工中不可缺少的部件，在機床技術向高速、高效、精密、復合、智能、環(huán)保方向發(fā)展的帶動下，夾具技術正朝著高精、高效、模塊、組合、通用、經(jīng)濟方向發(fā)展。 一、 高精 隨著機床加工精度的提高，為了降低定位誤差，提高加工精度對夾具的制造精度要求更高高精度夾具的定位孔距精度高達±0.5mm，夾具支撐面的垂直度達0.01mm/300mm，平行度高達 0.01mm/500mm。瑞士EROWA柔性夾具的重復定位精度高達2~5微米。機床夾具的精度已提高到微米級，世界知名的夾具制造公司都是精密機械制造企業(yè)。為了適應不同行業(yè)的需求和經(jīng)濟性，夾具有不同的型號以及不同檔次的精度標準供選擇。 二、 高效 為了提高機床的生產(chǎn)效率，雙面、四面和多件裝夾的夾具產(chǎn)品越來越多。為了減少工件的安裝時間，各種自動定心夾緊、精密平口鉗、杠桿夾緊、凸輪夾緊、氣動和液壓夾緊等，快速夾緊功能部件不斷的推陳出新。新型的電控永磁夾具，夾緊和松開工件只用1、2秒，夾具結(jié)構簡化，為機床進行多工位、多面和多件加工創(chuàng)造了條件。采用美國杰金斯公司的球鎖裝夾系統(tǒng)，1分鐘內(nèi)就能將夾具定位和鎖緊在機床工作臺上，球鎖裝夾系統(tǒng)用于柔性生產(chǎn)線上更換夾具，起到縮短停機時間，提高生產(chǎn)效率的作用。 三、 模塊 組合夾具元件模塊化是實現(xiàn)組合化的基礎。利用模塊化設計的系列化、標準化夾具元件，快速組裝成各種夾具，已成為夾具技術開發(fā)的基點。省工、省時、節(jié)材、節(jié)能，體現(xiàn)在各種先進夾具系統(tǒng)的創(chuàng)新之中。模塊化設計為夾具的計算機輔助設計與組裝打下了基礎。應用CAD技術，可建立元件庫、典型夾具庫、標準和用戶使用檔案庫，進行夾具優(yōu)化設計，為用戶三維實體組裝夾具。模擬仿真刀具的切削過程，既能為用戶提供正確、合理的夾具與元件配套方案，又能積累使用經(jīng)驗，了解市場需求，不斷的改進和完善夾具系統(tǒng)。 四、 通用 經(jīng)濟夾具的通用性直接影響其經(jīng)濟性。采用模塊、組合式的夾具系統(tǒng)，一次性投資比較大，只有夾具系統(tǒng)的可重組性、可重構性及可擴展性功能強，應用范圍廣，通用性好，夾具利用率高，收回投資快，才能體現(xiàn)出經(jīng)濟性好。 附錄： Cengage Learning In the machining process the work piece by the cutting force, centrifugal force, inertia force, such as the role of, in order to ensure that these external force, the workpiece can remain in the fixture by the positioning of the processing to determine the location of components, and should be no vibration or displacement, fixture structure should be set up reliable work piece clamping device folder will be in prison. First, the composition of clamping devices. Many different types of clamping devices, but their structures are composed of two parts. 1. Power plant The source of clamping force, one human; second is generated by a power device.The device can generate power as the power unit fixture. Commonly used in power plant are: pneumatic devices hydraulic devices electrical devices electromagnetic devices gas - liquid interaction devices and vacuum devices. Fixture as a result of manual clamping force from the human so it does not power plants. 2. Clamping part Receive and impart into the original clamping force to clamp the task force and part of the implementation of the general composition of the following agencies: 1) to accept the original force of bodies. Such as handles nuts and used to connect the institutions such as cylinder piston rod. 2) Force the middle of delivery. Such as hinges levers and so on. 3) Clamping components. Such as plate such as screws. Force delivery of them in the middle of the original transmission of force to the process of clamping devices can play such as changes in the direction of force to change the size of forces as well as the role of self-locking and so on. Second the basic requirements for clamping device Without damaging the work piece positioning accuracy and quality assurance process under the premise of clamping devices should be enabled to: 1. The size of the appropriate clamping force. It is necessary to ensure that the work piece in the whole process of its stable position vibration small but also so that the work piece does not produce excessive clamping deformation. 2. Technology is good. The complexity of the clamping device should be suited to the production of the Program to ensure production efficiency its structure should be kept simple easy to manufacture and maintenance. 3. Good use. The operation of clamping device should be convenient safe and labor-saving. Third the basic Clamp iginal force into a clamping force through the clamping body to achieve.Among the many institutions in the clamping wedge oblique spiral and by their eccentric combination of the most common application of clamping. (A) Wedge Clamp used as components or transmission of the clamping device clamping body known as the Wedge Clamp. Wedge clamping directly the oblique wedge of the self-locking conditions are:Wedge angle smaller than the work piece Wedge Wedge and folders between the concrete and the friction angle. Namely: α≤Φ1+Φ2 In order to ensure a reliable self-locking manual clamping generally take a =6 °~ 8 °. Using pneumatic or hydraulic device drivers do not need the self-locking oblique wedge it is desirable to a =15 ° ~35 °. Wedge clamp is simple in structure than by large self-locking features such as performance it is widely available. (B) Helical Clamp Used as intermediate screw transmission components are collectively referred to as the clamping screw clamping body organs. Because of its simple structure reliable clamping common good and as a result of the small helix angle spiral of self-locking clamping body good clamping force and the clamping itinerary are larger fixture on manual with the most a clamping body. 1. Simple screw clamp body The simplest spiral as a result of the direct use of clamping bodies pressed workpiece screw head so easy to damage the surface of the work piece under pressure or driven rotating work piece. So often in the head with swinging Press. Press with the work piece as a result of friction between the Press and the torque is greater than the friction between the screw torque screw together with the Press will not rotate. Clamping action slow time-consuming loading and unloading the work piece is a single spiral Another drawback of the Clamp. To overcome this shortcoming the rapid clamping bodies can be. 2. Clamp screw plate Institutions in the clamping the use of spiral plate is very common common structure of the spiral structure of a typical plate size has been standardized the designer can refer to the relevant national standards and fixture design manual design. (C) Eccentric Clamp With eccentric pieces, directly or indirectly, the work piece clamping body, known as the eccentric clamping body. There are two types of eccentric pieces, that is, and the curveof eccentricity eccentric circle, which, due to a round eccentric structure is simple and easy to manufacture and is widely used. Eccentric clamping processing is easy to operate, rapid clamp, the disadvantage of clamping force and clamping trip are small. Not generally used in cutting force, vibration small there is no centrifugal force of the impact of the processing. 1. Round the working principle of eccentric 2. Eccentric clamping round trip and paragraph 3. Eccentric self-locking condition of αmax≤Φ1+Φ2 Was derived: f1 ≥2e / D When f =0.1 hours, e / D≥ 20, when f =0.15 pm, e / D ≥14 Fourth institutions centering clamping When the work piece is processed by the central element of surface (axis, the center plane, etc.) for the base process in order to enable the base to reduce the positioning error of coincidence to be used centering clamping body. Centering centering clamping body and clamping the two functions such as horizontal self-centering three-jaw lathe chuck is a classic example of the most commonly used. Centering centering clamping the role of institutions according to their principle, there are two types, one is relying on the transmission mechanism so that mobile speed centering clamping device in order to achieve centering clamping, such as spiral leveraged institutions such as wedge; the other is the use of thin-walled elastic element force even after the elastic deformation (contraction or expansion), to achieve centering clamping, such as a spring clip drum, diaphragm chuck, bellows units, such as liquid plastic. 1. Centering clamping body spiral Rotary screw thread at both ends to the contrary, the same pitch. When it spins, the two V-shaped gag against the constant movement in order to achieve the centering of the work piece clamping or release. V-shaped work pieces of different shapes can shut up the replacement. Centering clamping bodies such features are: simple structure the work trip and general good but the centering accuracy is not high mainly suitable for rough or semi-finished tour of the needs of large and less demanding precision centering occasions. 2. Leveraged institutions centering clamping Three-jaw self-centering leveraged trading cards, sleeve for axial movement the circle are three fabric hook lever will rotate around the axis, the three struck the slider along the radial movement of the cards in order to promote its claws the work piece centering and clamping or release. This centering clamping rigid body, and move fast, by force multiplier, and the worktrip is also characterized by relatively large, but its relatively low precision centering. Generally about 0.1mm it is mainly used for rough work. Since the body can not self-locking lever, so that organizations rely on self-locking air pressure or other agencies. 3. Centering clamping wedge bodies Wedge mobile folder automatically centering body claw when the work piece surface within the hole and left the position in the fixture after the six-cylinder through the rod so that the left claw clip due to the role of ontology on the slope while the left claw folder to the opened outside the bulge will be centering the workpiece clamping the other hand claw shifted to right folder in the role of spring circle card folder under claw to release the work piece. Centering clamping bodies such compact structure usually ranging from precision centering 0.02mm~ 0.07mm compared with the hole for the workpiece surface for positioning the base of the semi-finishing processes. 4. Clip-on spring-centering clamping cylinder body This centering clamping sleeve body type commonly used in the installation of the work piece. Elastic centering clamping simple structure, small size, easy to operate quickly, so a wide range of applications. Centering accuracy of its stability in between0.04mm~ 0.010mm. In addition to the above described centering clamping bodies, are commonly used diaphragm chuck body, corrugated centering clamping sets of institutions, as well as fluid bodies such as plastic clamping. Machining fixture is an indispensable component in the machine tool technology to high-speed, high efficiency, precision, complex, intelligent, environmentally-friendly direction, driven by technology is moving fixture high-precision, high-performance, modular, mix, general economic direction. First, high-precision Machining with improved accuracy, in order to reduce the positioning error and improve machining accuracy of the fixture manufacturing precision demanding high-precision positioning jig Distance accuracy up to ± 5μm the bearing surface of the vertical fixture achieve 0.01mm / 300mm up to parallelism0.01mm/500mm. Switzerland duplication EROWA Flexible fixture positioning accuracy of up to 2 ~5μm. Precision machine tool fixture to the micron level has been raised the worlds leading manufacturer of fixture is precision machinery manufacturing enterprises. It is true that, in order to meet the needs of different industries and economy, folders with different models, as well as the different grades for the accuracy of the standard options. Second, efficient tool To improve production efficiency, double-sided, four and more than clamping fixture of more and more products. Work piece in order to reduce the installation time, all kinds of auto-centering clamping, precision flat clamp, clamping levers, cam clamp, such as pneumatic and hydraulic clamping, rapid clamping new features constantly. New type of electronically controlled permanent magnet fixture, step up and release the work piece only 1~2 seconds, simplifying the fixture structure for the machine to carry out stage, faceted and processing to create the condition. American JERGENS the company's ball lock clamping system,1 minutes, will be able to locate and lock fixture in the machine tool table, the ball lock clamping system of flexible production line for the replacement of fixtures, played reduce downtime and increase the role of productivity. Third, modules Modular components of modular fixture is the basis of the realization of portfolio. Take advantage of the modular design of serialization, standardization fixture elements, quickly assembled into a variety of fixtures, has become a fixture technology development basis points.Save labor, time, materials, energy-saving, being reflected in a variety of advanced fixture system innovation. The modular design laid the foundation for the the fixture computer-aided design and assembly. Application of CAD technology to create a component library the typical fixture library, standard and user archive fixture optimization design, assembly fixtures for users dimensional solid. Cutting process simulation tool, both to provide users with the correct fixtures and components supporting the program, but also the accumulation of experience, understand the market demand, and continue to improve and perfect the fixture system. Fourth, GM Economic fixture versatility direct impact on the economy. Modules, modular fixture system, a one-time investment is relatively large, the only fixture system reconfigurable and scalability features a wide range of applications, common good, fixture utilization, faster recovery of investment to reflect the economic good. 13 指 導 教 師 評 語 外文翻譯成績： 指導教師簽字： 年 月 日 注：1. 指導教師對譯文進行評閱時應注意以下幾個方面：①翻譯的外文文獻與畢業(yè)設計（論文）的主題是否高度相關，并作為外文參考文獻列入畢業(yè)設計（論文）的參考文獻；②翻譯的外文文獻字數(shù)是否達到規(guī)定數(shù)量（3 000字以上）；③譯文語言是否準確、通順、具有參考價值。 2. 外文原文應以附件的方式置于譯文之后。