【正文】 Note that this is also about the correct rotation for the wheel nuts of a passenger car. 注意這也是關(guān)于客車車輪螺母預(yù)緊的正確轉(zhuǎn)數(shù)。 The snugtight condition is the tightness attained by a few impacts of an impact wrench, or the full effort of a man using an ordinary wrench. 適度緊的狀態(tài)就是借助于沖擊扳手沖擊幾次所達到的預(yù)緊度，或一個男人用普通扳手盡全力上緊的程度。 Then torque wrenching, pneumaticimpact wrenching, or the turnofthenut method may be used. 扭矩扳手，氣動沖擊扳手，或螺帽旋動圈數(shù)扳手法等可用于測定預(yù)載荷。這就保證了已經(jīng)達到了所希望的預(yù)緊載荷。 機械工程專業(yè)英語 Lesson 19 Screws, fasteners and joints Having learned that a high preload is very desirable in important bolted connections, we must next consider means of assuring that the preload is actually developed when the parts are assembled. 課文分析 已經(jīng)知道：高預(yù)載荷在重要的螺栓聯(lián)接中是非常希望的。 機械工程專業(yè)英語 Lesson 19 Screws, fasteners and joints In such a joint the bolt has first been tightened to produce an initial tensile preload, after which the external tensile load and the external shear load are applied. 課文分析 在這種螺紋聯(lián)接中，首先把螺栓上緊以產(chǎn)生一預(yù)緊載荷初拉力，而后施加外拉力載荷和剪切載荷。 It is the intent, rather than the actual use, which determines the name of a product. 因而根據(jù)使用的目的來確定產(chǎn)品名稱，并不是根據(jù)其實際使用來命名的。如果所設(shè)計的產(chǎn)品打算跟螺母配合使用，那就是螺栓。 增生 Fasteners are named according to how they are intended to be used rather than how they are actually employed in specific instances. 課文分析 緊固件是根據(jù)將如何使用他們來命名的，而不是根據(jù)其在具體例子中的實際應(yīng)用命名的。 機械工程專業(yè)英語 Lesson 19 Screws, fasteners and joints To keep cost down, Boeing, Lockheed, and their subcontractors constantly review new fastener designs, installation techniques, and tooling. 課文分析 為了降低成本，波音、洛克希德和他們的承包商不斷重新審查緊固件的設(shè)計、安裝和切削加工。 機械工程專業(yè)英語 Lesson 19 Screws, fasteners and joints Jumbo jets such as Boeing’s 747 and Lockheed’s 1011 require as many as million fasteners, some of which cost several dollars apiece. 課文分析 大型噴氣發(fā)動機客機像被音 747和洛克希德 1011，需要 250萬個緊固件，有些每個要花數(shù)美元。 機械工程專業(yè)英語 Lesson 19 Screws, fasteners and joints In the material to follow you will discover the why of these questions. You will learn why a nut or bolt loosens and what you must do to keep it tight. 課文分析 在下面的文字中你將發(fā)現(xiàn)這些問題的原因。 機械工程專業(yè)英語 Lesson 19 Screws, fasteners and joints Could one seriously imagine a group of nut and bolt manufacturers anizing an association and getting together for annual meeting? What subject could possibly be of any interest? 課文分析 可以認真地設(shè)想有一群螺栓螺帽制造者組成一個協(xié)會并在一起召開年會嗎？那么還有什么學(xué)科不能讓人感興趣呢？ In spite of this taint, the subject is one of the most interesting in the entire field of mechanical design. 盡管存在這一偏見，但是這一學(xué)科在機械設(shè)計整個領(lǐng)域中卻是最使人感興趣的學(xué)科之一。 Parts may also be joined by welding, brazing, or clipping together. 零件聯(lián)接也可以用熔焊、銅焊和夾緊的方法。 ?鉸制孔用螺栓聯(lián)接：孔和螺栓桿多采用基孔制過渡配合（H7/m H7/n6） ,精確固定被聯(lián)接件的相對位置，并可承受橫向載荷。t hold true. The load seen by the hardware is the preload plus the external load. 機械工程專業(yè)英語 預(yù)備知識 一、 Background information Lesson 19 Screws, fasteners and joints 機械工程專業(yè)英語 預(yù)備知識 一、 Background information Lesson 19 Screws, fasteners and joints Theory The results of this type of joint design are: Greater preloads in bolted joints reduce the fatigue loading of the hardware. For cyclic loads, the bolt does not see the full amplitude of the load. As a result, fatigue life can be increased or, if the material exhibits an endurance limit, extended indefinitely. As long as the external loads on a joint don39。 stiffness with respect to the hardware39。 Lesson 19 Screws, fasteners and joints 機械工程專業(yè)英語 機械工程專業(yè)英語 預(yù)備知識 一、 Background information Lesson 19 Screws, fasteners and joints Bolted joints are one of the most mon elements in construction and machine design. They consist of cap screws or studs that capture and join other parts, and are secured with the mating of screw threads. There are two main types of bolted joint designs. In one method the bolt is tightened to a calculated clamp load, usually by applying a measured torque load. The joint will be de