【正文】 與艱苦、單調(diào)的工作同義，乏味但必須的工作。 機(jī)械工程專業(yè)英語 Lesson 19 Screws, fasteners and joints Studies in engineering graphics and in metal processes often include instruction on various joining methods, and the curiosity of any person interested in engineering naturally results in acquisition of a good background of fastening methods. 課文分析 在工程圖和金屬加工工藝研究中常常包括關(guān)于各種聯(lián)接方法的說明，在工程上對(duì)此很感興趣的，求知欲強(qiáng)的任何人自然會(huì)獲得關(guān)于固緊方法上良好的基礎(chǔ)知識(shí)。 ?控制預(yù)緊力的方法： 1）借助測(cè)力矩扳手或定力矩扳手 2）測(cè)定螺栓伸長量 機(jī)械工程專業(yè)英語 預(yù)備知識(shí) 一、預(yù)備知識(shí) Lesson 19 Screws, fasteners and joints 螺紋的防松 ?螺紋升角小于螺旋副的當(dāng)量摩擦角 ：自鎖性好 ?螺母與螺栓頭部等支承面上的摩擦力 ?摩擦防松：鎖緊螺母、彈簧墊圈、自鎖螺母 ?機(jī)械防松：開口銷與槽形螺母、止動(dòng)墊圈 ?鉚沖防松：端鉚、沖點(diǎn) 詞 匯 二、詞匯 screw 螺釘 、 螺紋 bolt 螺栓 nut 螺母 stud bolt 雙頭螺栓 washer 墊圈 thread 螺紋 機(jī)械工程專業(yè)英語 Lesson 19 Screws, fasteners and joints 課文分析 機(jī)械工程專業(yè)英語 Lesson 19 Screws, fasteners and joints Typical methods of fastening and joining parts include the use of such items as bolts, nuts, cap screws, setscrews, rivets, locking devices and keys. Parts may also be joined by welding, brazing, or clipping together. Studies in engineering graphics and in metal processes often include instruction on various joining methods, and the curiosity of any person interested in engineering naturally results in acquisition of a good background of fastening methods. Typical methods of fastening and joining parts include the use of such items as bolts, nuts, cap screws, setscrews, rivets, locking devices and keys. 課文分析 典型的緊固件和聯(lián)接件包括諸如螺栓、螺帽、有頭螺釘、緊定螺釘、鉚釘、鎖緊裝置和鍵。 ?雙頭螺栓聯(lián)接：被聯(lián)接件之一太厚或經(jīng)常拆裝 ?螺釘聯(lián)接：不用螺母，比雙頭螺柱簡單，用途相似，多用于受力不大、不需經(jīng)常拆裝的場(chǎng)合 ?緊定螺釘聯(lián)接：固定兩零件的相對(duì)位置，可傳遞不太大的扭矩和力 ?螺栓的類型：六角頭螺栓和雙頭螺栓 ?螺釘?shù)念愋停喊雸A頭、平頭、六角頭、圓柱頭、沉頭 機(jī)械工程專業(yè)英語 預(yù)備知識(shí) 一、預(yù)備知識(shí) Lesson 19 Screws, fasteners and joints 螺紋的預(yù)緊 ?預(yù)緊的目的：增強(qiáng)聯(lián)接的可靠性、緊密性，防止受載后被聯(lián)接件間出現(xiàn)縫隙或發(fā)生相對(duì)滑移。t hold true. The load seen by the hardware is the preload plus the external load. 機(jī)械工程專業(yè)英語 預(yù)備知識(shí) 一、 Background information Lesson 19 Screws, fasteners and joints Thread strength Nut threads are designed to support the rated clamp load of their respective bolts. If tapped threads are used instead of a nut, then their strength needs to be calculated. Steel hardware into tapped steel threads requires a depth of thread diameter to support the full clamp load. If an appropriate depth of threads is not available, or the threads are in a weaker material than the cap screw, then the clamp load (and torque) needs to be derated appropriately. 機(jī)械工程專業(yè)英語 預(yù)備知識(shí) 一、 Background information Lesson 19 Screws, fasteners and joints Failure modes The most mon mode of failure is overloading. Operating forces of the application produce loads that exceed the clamp load and the joint works itself loose, or fails catastrophically. Over torquing will cause failure by damaging the threads and deforming the hardware, the failure might not occur until long afterward. Under torquing can cause failures by allowing a joint to e loose. It may also allow the joint to flex and thus fail under fatigue. Brinelling may occur with poor quality washers, leading to a loss of clamp load and failure of the joint. Corrosion, embedment and exceeding the shear stress limit are other modes of failure. 機(jī)械工程專業(yè)英語 預(yù)備知識(shí) 一、 Background information Lesson 19 Screws, fasteners and joints Notes: Brinelling refers to a material surface failure caused by contact stress that exceeds the material limit. This failure is caused by just one application of a load great enough to exceed the material limit. The result is a permanent dent or brinell mark. Embedment is a phenomenon in mechanical engineering in which the surfaces between mechanical members of a loaded joint embed. It can lead to failure by fatigue as described below, and is of particular concern when considering the design of critical fastener joints. 機(jī)械工程專業(yè)英語 預(yù)備知識(shí) 一、預(yù)備知識(shí) Lesson 19 Screws, fasteners and joints 基本類