【正文】 先進制造技術(shù)中的一個最基本的概念是數(shù)字控制（NC）。 the variant approach ,a set of standard process plans is established for all parts families that have been identified through group technology.在派生法中，對采用成組技術(shù)確定的一個零件族中的所有零件，編制一套標準的加工工藝規(guī)程。其中包括已建立的標準，可加工性數(shù)據(jù)，機器的規(guī)格，工藝裝備的清單，原材料庫存量和一些目前正在應(yīng)用的工藝文件。 Many of today^s more sophisticated lathes are called machining centers since they are capable of performing, in addition to the normal turning operations, certain milling and drilling operations.當(dāng)前許多技術(shù)更為先進的車床叫做加工中心。 The first screw machine were designed to feed bar stock and wire used in making small screw parts.單軸自動螺絲車床，顧名思義，一次僅能加工一根棒料。 The tracer or duplicating lathe is designed to produce irregularly shaped parts automatically. 靠模車床或仿形車床被設(shè)計用來對形狀不規(guī)則的零件進行自動加工。Computer of applications in engineering and other technical fields. Most graphical solutions that are possible with a pencil can be done on a puter and usually more productively. Applications vary from 3D modeling and finite element analysis to 2D drawings and mathematical caiculation.計算機圖形學(xué)在工程技術(shù)領(lǐng)域的應(yīng)用幾乎沒有任何限制，大部分可以鉛筆完成的圖解方法都可以用計算機完成，而且通常效率更高。例如，一個零件的尺寸可以被表示成20+，其公差（尺寸變動量）。公差的大小是由設(shè)計人員所確定的，它取決于許多與設(shè)計有關(guān)的條件以及過去在設(shè)計類似產(chǎn)品時所獲得的經(jīng)驗（如果有這方面經(jīng)驗的話）。Title Blocks In practice, title blocks usually contain the title or part name, drafter, date, scale, pany, and sheet number. Other information, such as tolerances, checkers, and materials, also may be given. Any modifications or changes added after the first version to improve the design is shown in the revision blocks. 標題欄 在實踐中，標題欄中通常包括標題或零件名稱、制圖員、日期、比例、公司和圖號。經(jīng)驗表明，可以采用某些便宜材料作為代替。 (c) production design. During the conceptualdesign stage, the designer is concerned primarily with the functions the product is to fulfill. 制造任何產(chǎn)品的第一步工作都是設(shè)計。這表明由于硬度是非破壞性試驗，而且不需要專門的試件，因而硬度是一個容易測量的性能。Ideally, in designing any machine element, the engineer should have at his disposal the results of a great many strength tests of the particular material chosen. These tests should have been made on specimens having the same heat treatment, surface roughness, and size as the element he proposes to design, and the tests should be made under exactly the same loading conditions as the part will experience in service.設(shè)計任何機械零件的理想情況為，工程師可以利用大量的他所選用的這種材料的強度試驗數(shù)據(jù)。在軸承內(nèi)圈上加工出一個圓弧或者倒角，用來提供容納軸肩處圓弧半徑的空間。It is not surprising that ,owing to the high stresses involved,a predominant form of failure shouls be metal fatigue,and a good deal of work is currently in progress intended to improve the reliability of this type of bearing . 滾動軸承由于在工作中會產(chǎn)生高的應(yīng)力，其主要失效形式是金屬疲勞，這一點并不奇怪，目前正在進行大量的工作以求改進這種軸承的可靠性。因此，在為一個特定的用途選擇緊固件時，應(yīng)該考慮到上述各種可能性。人們對于任何產(chǎn)品的滿意程度不僅取決于其組成部件，還取決于其連接方式。這是由剛性或者彈性聯(lián)軸器來實現(xiàn)的。3 、Components such as gears and pulleys are mounted on shafts by means of key. The design of the key and the corresponding keyway in the shaft must be properly evaluated. For example, stress concentrations occur in shafts due to keyways, and the material removed to from the keyway further weakens the shaft.齒輪和皮帶輪等零件通過鍵連接在軸上。軸的最常見的形狀是圓形，其截面可以是實心的，也可以是空心的（空心軸可以減輕重量）。Lesson2（此課后面沒翻譯，翻譯的不太準確諒解）1 、The turning of a part in a lathe is another example of several forces in action.（as shown in figure1） 車床車削是一些力在起作用的另一個例子。標量是那些只有大小的量。靜力學(xué)對靜止系統(tǒng)進行分析，即在其中不考慮時間這個引述，動力學(xué)對事件而變化的系統(tǒng)進行分析。他由靜力學(xué)和動力學(xué)兩部分組成。Mechanics deal with two kinds of quantities: scalars and vectors. Scalar quantities are those with which a magnitude alone is associated. Examples of scalar quantities in mechanics are time, volume, density, speed, energy, and mass. Vector quantities, on the other hand, possess direction as well as magnitude. Examples of vectors are displacement, velocity, acceleration, force, moment, and momentum.力學(xué)涉及兩種類型的量，標量 和矢量。矢量的例子有位移、速度、加速度、力、力矩、動量。 Rotary motio