English for Mechanical Engineering机械工程专业英语常州工学院机电工程学院徐红丽Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd. Slotted cone pointed set screw. Hex nut. Slotted nut . Bright washer. Spring washer. Tab washer 锥端紧定螺钉锥端紧定螺钉锥端紧定螺钉锥端紧定螺钉 六角螺母六角螺母六角螺母六角螺母 六角槽形螺母六角槽形螺母六角槽形螺母六角槽形螺母 平垫圈平垫圈平垫圈平垫圈 弹簧垫圈弹簧垫圈弹簧垫圈弹簧垫圈 外舌止动垫圈外舌止动垫圈外舌止动垫圈外舌止动垫圈Hexagon head bolt. Stud. Slotted cheese head screw. Slotted pan head screw. Slotted countersunk screw. Hexagon socket cap 六角头螺钉六角头螺钉六角头螺钉六角头螺钉 双头螺柱头双头螺柱头双头螺柱头双头螺柱头 圆柱头螺钉圆柱头螺钉圆柱头螺钉圆柱头螺钉 盘头螺钉盘头螺钉盘头螺钉盘头螺钉 沉头螺钉沉头螺钉沉头螺钉沉头螺钉 圆柱头内六角螺钉圆柱头内六角螺钉圆柱头内六角螺钉圆柱头内六角螺钉 Types of screw fasteners 螺纹螺纹紧固件紧固件的的种类种类 Parts with threads used for joining and fastening are Parts with threads used for joining and fastening are called screw fasteners. The most widely used called screw fasteners. The most widely used components as screw fasteners are bolts, double screw components as screw fasteners are bolts, double screw bolts-stud, screws, nuts and washersbolts-stud, screws, nuts and washers。 用螺纹联接并起紧固作用的零件称为螺纹紧固件。常用的用螺纹联接并起紧固作用的零件称为螺纹紧固件。常用的用螺纹联接并起紧固作用的零件称为螺纹紧固件。常用的用螺纹联接并起紧固作用的零件称为螺纹紧固件。常用的螺纹紧固件有螺纹紧固件有螺纹紧固件有螺纹紧固件有螺栓螺栓螺栓螺栓、双头螺柱双头螺柱双头螺柱双头螺柱、螺钉螺钉螺钉螺钉、螺母螺母螺母螺母、垫圈垫圈垫圈垫圈等等等等。Lesson 19 Screws, fasteners and joints 机械工程专业英语机械工程专业英语Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background informationLesson 19 Screws, fasteners and joints Bolted joints are one of the most common 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 designed such that the clamp load is never overcome by the forces acting on the joint (and therefore the joined parts see no relative motion). The other type of bolted joint does not have a designed clamp load but relies on the shear strength of the bolt shaft. This may include clevis linkages, joints that can move, and joints that rely on locking mechanism (like lock washers, thread adhesives, and lock nuts).Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background informationLesson 19 Screws, fasteners and joints Bolted joint Screw joint Stud joint Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd. Bolt 螺 栓 The bolt assembly is used when joint parts are not too thick to drill through holes. 螺栓螺栓 用于联接二通孔薄件用于联接二通孔薄件Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd. Stud 双头螺柱Stud are used in situations where a part with a through hole and a part with blind tapped hole.双头螺柱双头螺柱 用于联接一通孔薄件和一盲孔厚件。用于联接一通孔薄件和一盲孔厚件。Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd. Screw 螺 钉Screws are mostly used for the cases with small bearing forces. such as inspection covers which have to be removed frequently.螺钉螺钉 多多用于用于用于受力不大用于受力不大需要经常拆卸需要经常拆卸的情况的情况Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd. Nut 螺 母Nut are used to match the other screw fasteners. 螺母螺母 与其他螺纹件配合使用与其他螺纹件配合使用Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd. Washer 垫 圈弹簧垫圈弹簧垫圈弹簧垫圈弹簧垫圈 平垫圈平垫圈平垫圈平垫圈Washer are used to match the other screw fasteners. 垫圈垫圈 与其他螺纹件配合使用与其他螺纹件配合使用Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background informationLesson 19 Screws, fasteners and joints Theory The clamp load, also called preload, of a cap screw is created when a torque is applied, and is generally a percentage of the cap screws proof strength. Cap screws are manufactured to various standards that define, among other things, their strength and clamp load. Torque charts are available that identify the required torque for cap screws based on their property class or grade. When a cap screw is tightened it is stretched, and the parts that are captured are compressed. The result is a spring-like assembly. External forces are designed to act on the parts that have been compressed, and not on the cap screw.Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background informationLesson 19 Screws, fasteners and joints Theory The result is a non-intuitive distribution of strain; in this engineering model, as long as the forces acting on the compressed parts do not exceed the clamp load, the cap screw do not see any increased load. This model is only valid when the members under compression are much stiffer than the cap screw. This is a simplified model. In reality the bolt will see a small fraction of the external load prior to it exceeding the clamp load, depending on the compressed parts stiffness with respect to the hardwares stiffness. Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background informationLesson 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 dont exceed the clamp load, the hardware doesnt see any motion and will not come loose (no locking mechanisms are required). In the case of the compressed member being less stiff than the hardware (soft, compressed gaskets for example) this analogy doesnt hold true. The load seen by the hardware is the preload plus the external load.Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background informationLesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background informationLesson 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 dont exceed the clamp load, the hardware doesnt see any motion and will not come loose (no locking mechanisms are required). In the case of the compressed member being less stiff than the hardware (soft, compressed gaskets for example) this analogy doesnt hold true. The load seen by the hardware is the preload plus the external load.Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background informationLesson 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 1.5 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.Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background informationLesson 19 Screws, fasteners and joints Failure modes The most common 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 come 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.Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、一、Background informationLesson 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.Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、预备知识一、预备知识Lesson 19 Screws, fasteners and joints 1、基本类型、基本类型u普通螺栓联接：被联接件上通孔和螺栓杆间留有间隙，故普通螺栓联接：被联接件上通孔和螺栓杆间留有间隙，故精度低、结构简单。精度低、结构简单。u铰制孔用螺栓联接：孔和螺栓杆多采用基孔制过渡配合铰制孔用螺栓联接：孔和螺栓杆多采用基孔制过渡配合（H7/m6、H7/n6）,精确固定被联接件的相对位置，并可承精确固定被联接件的相对位置，并可承受横向载荷。受横向载荷。u双头螺栓联接：被联接件之一太厚或经常拆装双头螺栓联接：被联接件之一太厚或经常拆装u螺钉联接：不用螺母，比双头螺柱简单，用途相似，多用螺钉联接：不用螺母，比双头螺柱简单，用途相似，多用于受力不大、不需经常拆装的场合于受力不大、不需经常拆装的场合u紧定螺钉联接：固定两零件的相对位置，可传递不太大的紧定螺钉联接：固定两零件的相对位置，可传递不太大的扭矩和力扭矩和力u螺栓的类型：六角头螺栓和双头螺栓螺栓的类型：六角头螺栓和双头螺栓u螺钉的类型：半圆头、平头、六角头、圆柱头、沉头螺钉的类型：半圆头、平头、六角头、圆柱头、沉头 Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、预备知识一、预备知识Lesson 19 Screws, fasteners and joints 2、螺纹的预紧、螺纹的预紧u预紧的目的：增强联接的可靠性、紧密性，防止预紧的目的：增强联接的可靠性、紧密性，防止受载后被联接件间出现缝隙或发生相对滑移。选用受载后被联接件间出现缝隙或发生相对滑移。选用较大的预紧力可提高联接的可靠性和疲劳强度较大的预紧力可提高联接的可靠性和疲劳强度u预紧应力不超过其材料的屈服极限的预紧应力不超过其材料的屈服极限的80%。u控制预紧力的方法：控制预紧力的方法： 1）借助测力矩扳手或定力矩扳手）借助测力矩扳手或定力矩扳手 2）测定螺栓伸长量）测定螺栓伸长量Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.机械工程专业英语机械工程专业英语预备知识预备知识 一、预备知识一、预备知识Lesson 19 Screws, fasteners and joints 3、螺纹的防松、螺纹的防松u螺纹升角小于螺旋副的当量摩擦角螺纹升角小于螺旋副的当量摩擦角 ：自锁性好：自锁性好u螺母与螺栓头部等支承面上的摩擦力螺母与螺栓头部等支承面上的摩擦力u摩擦防松：锁紧螺母、弹簧垫圈、自锁螺母摩擦防松：锁紧螺母、弹簧垫圈、自锁螺母u机械防松：开口销与槽形螺母、止动垫圈机械防松：开口销与槽形螺母、止动垫圈u铆冲防松：端铆、冲点铆冲防松：端铆、冲点Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.词词 汇汇 二、词汇二、词汇screw 螺螺钉钉、螺螺纹纹 bolt 螺螺栓栓 nut 螺螺母母 stud bolt 双双头头螺螺栓栓 washer 垫垫圈圈 thread 螺纹螺纹机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.课文分析课文分析机械工程专业英语机械工程专业英语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. Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.Typical methods of fastening and joining parts include the use of such items as bolts, nuts, cap screws, setscrews, rivets, locking devices and keys.课文分析课文分析典型的紧固件和联接件包括诸如螺栓、螺帽、有头螺典型的紧固件和联接件包括诸如螺栓、螺帽、有头螺钉、紧定螺钉、铆钉、锁紧装置和键。钉、紧定螺钉、铆钉、锁紧装置和键。 Parts may also be joined by welding, brazing, or clipping together. 零件联接也可以用熔焊、铜焊和夹紧的方法。零件联接也可以用熔焊、铜焊和夹紧的方法。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.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. 课文分析课文分析在工程图和金属加工工艺研究中常常包括关于各种联在工程图和金属加工工艺研究中常常包括关于各种联接方法的说明，在工程上对此很感兴趣的，求知欲强接方法的说明，在工程上对此很感兴趣的，求知欲强的任何人自然会获得关于固紧方法上良好的基础知识。的任何人自然会获得关于固紧方法上良好的基础知识。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.课文分析课文分析机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints If an uninformed person were asked to choose the dullest and most uninteresting subject in mechanical design that he could imagine, he might well choose the subject of fasteners, that is, nuts and bolts. In fact, the term “nuts and bolts” is synonymous with hard and monotonous work, necessary but totally uninteresting tasks. Could one seriously imagine a group of nut and bolt manufacturers organizing an association and getting together for annual meeting? What subject could possibly be of any interest? Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.If an uninformed person were asked to choose the dullest and most uninteresting subject in mechanical design that he could imagine, he might well choose the subject of fasteners, that is, nuts and bolts. 课文分析课文分析如果让一个对紧固件不甚了解的人去选择他能想象的如果让一个对紧固件不甚了解的人去选择他能想象的机械设计方面最枯燥无味的学科的话，那么他就会选机械设计方面最枯燥无味的学科的话，那么他就会选择紧固件学科，即螺栓和螺帽。择紧固件学科，即螺栓和螺帽。 In fact, the term “nuts and bolts” is synonymous with hard and monotonous work, necessary but totally uninteresting tasks. 事实上，术语事实上，术语“螺栓和螺帽螺栓和螺帽”是与艰苦、单是与艰苦、单调的工作同义，乏味但必须的工作。调的工作同义，乏味但必须的工作。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.Could one seriously imagine a group of nut and bolt manufacturers organizing an association and getting together for annual meeting? What subject could possibly be of any interest? 课文分析课文分析可以认真地设想有一群螺栓螺帽制造者组成一个协会可以认真地设想有一群螺栓螺帽制造者组成一个协会并在一起召开年会吗？那么还有什么学科不能让人感并在一起召开年会吗？那么还有什么学科不能让人感兴趣呢？兴趣呢？ In spite of this taint, the subject is one of the most interesting in the entire field of mechanical design. 尽管存在这一偏见，但是这一学科在机械设计整个尽管存在这一偏见，但是这一学科在机械设计整个领域中却是最使人感兴趣的学科之一。领域中却是最使人感兴趣的学科之一。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.The number of new inventions in the fastener field over any period you might care to mention has been tremendous. 课文分析课文分析在紧固件领域新发明的数目巨大超过你能注意到的任在紧固件领域新发明的数目巨大超过你能注意到的任何时期何时期There is an overwhelming variety of fasteners available for the designers selection. 数不胜数的紧固件可供设计者任意选择使用。数不胜数的紧固件可供设计者任意选择使用。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.Another thing: did you know that a good bolt material should be strong and tough, but a good nut material should be soft and ductile? 课文分析课文分析还有，你知道吗？好的螺栓的材料应该是坚固而有韧还有，你知道吗？好的螺栓的材料应该是坚固而有韧性，而好的螺帽的材料应该是软而有塑性的。性，而好的螺帽的材料应该是软而有塑性的。 Or did you know that there are certain applications where you should tighten the bolt as tightly as possible and, if it does not fail by twisting the bolt in two during tightening, there is a very good possibility that the bolt never will fail? 或者你知道吗或者你知道吗?在某些应用中你应该尽可能地把它们在某些应用中你应该尽可能地把它们旋紧，如果在上紧过程中，由于旋紧这螺栓过程中而旋紧，如果在上紧过程中，由于旋紧这螺栓过程中而未发生失效现象，那么螺栓将可能永远不会失效。未发生失效现象，那么螺栓将可能永远不会失效。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.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. 课文分析课文分析在下面的文字中你将发现这些问题的原因。你将掌握在下面的文字中你将发现这些问题的原因。你将掌握螺栓、螺帽为什么会松动和你必须怎样令它保持旋紧螺栓、螺帽为什么会松动和你必须怎样令它保持旋紧状态。状态。 Methods of joining parts are extremely important in the engineering of a quality design, and it is necessary to have a thorough understanding of the performance of fasteners and joints under all conditions of use and design. 联接件的联接方法在保证工程设计质量方面是极端重联接件的联接方法在保证工程设计质量方面是极端重要的。在设计和使用的各种情况下，充分了解紧固件要的。在设计和使用的各种情况下，充分了解紧固件和联接件的性能那是必要的。和联接件的性能那是必要的。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.Jumbo jets such as Boeings 747 and Lockheeds 1011 require as many as 2.5 million fasteners, some of which cost several dollars apiece. 课文分析课文分析大型喷气发动机客机像被音大型喷气发动机客机像被音747和洛克希德和洛克希德1011，需，需要要250万个紧固件，有些每个要花数美元。万个紧固件，有些每个要花数美元。 The 747, for example, needs about 70,000 titanium fasteners, costing about $150,000 in all; 400,000 other close-tolerance fasteners, costing about $250,000; and 30,000 squeeze rivets priced at 50 cents each, installed. 例如波音例如波音747，大约需要装，大约需要装70000个钛合金紧固件，个钛合金紧固件，全部大约要花全部大约要花150000美元；美元；400000个具有精密公差个具有精密公差的其他紧固件，大约要花的其他紧固件，大约要花250000美元；和美元；和30000个个挤压用铆钉，安装后每个价值挤压用铆钉，安装后每个价值50美分。美分。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.To keep cost down, Boeing, Lockheed, and their subcontractors constantly review new fastener designs, installation techniques, and tooling. 课文分析课文分析为了降低成本，波音、洛克希德和他们的承包商不为了降低成本，波音、洛克希德和他们的承包商不断重新审查紧固件的设计、安装和切削加工。断重新审查紧固件的设计、安装和切削加工。 Cost-saving designs and tooling will find a ready market, which will grow in value as jumbo jets proliferate. 节省的设计和加工成本将开发一个畅销市场，增长节省的设计和加工成本将开发一个畅销市场，增长的价值那将像坐上喷气式飞机一样。的价值那将像坐上喷气式飞机一样。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints pru5 5lifreitvi. 激增激增; 繁殖繁殖; 增生增生Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.Fasteners are named according to how they are intended to be used rather than how they are actually employed in specific instances. 课文分析课文分析紧固件是根据将如何使用他们来命名的，而不是根紧固件是根据将如何使用他们来命名的，而不是根据其在具体例子中的实际应用命名的。据其在具体例子中的实际应用命名的。 If this basic fact is remembered, it will not be difficult to distinguish between a screw and a bolt. 如果记住了这个基本事实，就将不难区别螺钉和螺如果记住了这个基本事实，就将不难区别螺钉和螺栓。栓。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.If a product is designed so that its primary purpose is assembly into a tapped hole, it is a screw. Thus a screw is tightened by exerting torque on the head. If a product is designed so that it is intended to be used with a nut, it is a bolt. 课文分析课文分析如果所设计的产品其主要目的是把它装入到已攻丝如果所设计的产品其主要目的是把它装入到已攻丝的螺纹孔中，那就是螺钉。这样螺钉是要在螺钉头的螺纹孔中，那就是螺钉。这样螺钉是要在螺钉头上施加扭矩来旋紧的。如果所设计的产品打算跟螺上施加扭矩来旋紧的。如果所设计的产品打算跟螺母配合使用，那就是螺栓。母配合使用，那就是螺栓。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.A bolt is tightened by exerting torque on the nut. A stud resembles a threaded rod; one end assembles into a tapped hole, the other end receives a nut. 课文分析课文分析螺栓是靠在螺母上施加扭矩来旋紧的。双头螺栓就螺栓是靠在螺母上施加扭矩来旋紧的。双头螺栓就像刻了螺纹的杆，一端旋入螺纹孔中，另一端再装像刻了螺纹的杆，一端旋入螺纹孔中，另一端再装上螺帽。上螺帽。It is the intent, rather than the actual use, which determines the name of a product. 因而根据使用的目的来确定产品名称，并不是根据因而根据使用的目的来确定产品名称，并不是根据其实际使用来命名的。其实际使用来命名的。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.Thus it may be desirable on various occasions to use a drill to drill a hole through two sheets of steel, say, and joint them using a screw and a nut. 课文分析课文分析这样，在各种场合用钻头给两块钢板钻通孔，人们这样，在各种场合用钻头给两块钢板钻通孔，人们就会用螺栓和螺帽来连接它们，这可能是人们所希就会用螺栓和螺帽来连接它们，这可能是人们所希望的。望的。 There are four forms of head most commonly used with cap screw: hexagon head, fillister head, flat head and hexagon socket head. 有帽螺钉最常用的四种螺钉头的形式是：六角头，有帽螺钉最常用的四种螺钉头的形式是：六角头，槽头，平头和内六角沉头。槽头，平头和内六角沉头。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.When a connection is desired which can be disassembled without destructing the parts assembled and which is strong enough to resist both external tensile load and shear load, or a combination of these, then the simple bolted joint using hardened washers is a good solution. 课文分析课文分析当需要一个螺纹联接即可以拆开又不破坏被联接件，当需要一个螺纹联接即可以拆开又不破坏被联接件，而且这个联接又要有足够的强度以承受外拉力和剪而且这个联接又要有足够的强度以承受外拉力和剪力或这两种力的合力时，使用带淬火垫圈的简单螺力或这两种力的合力时，使用带淬火垫圈的简单螺栓联接是一个很好的解决方法。栓联接是一个很好的解决方法。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.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. 课文分析课文分析在这种螺纹联接中，首先把螺栓上紧以产生一预紧在这种螺纹联接中，首先把螺栓上紧以产生一预紧载荷初拉力，而后施加外拉力载荷和剪切载荷。载荷初拉力，而后施加外拉力载荷和剪切载荷。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.The effect of the preload is to place the parts in compression for better resistance to the external tensile load and to create friction between the parts to resist the shear load. 课文分析课文分析预载荷的作用是使被连接件处于压应力状态以更好预载荷的作用是使被连接件处于压应力状态以更好地抵抗外部拉伸载荷和产生摩擦力以抵抗剪切载荷。地抵抗外部拉伸载荷和产生摩擦力以抵抗剪切载荷。The importance of preloading of bolts cannot be overestimated. A high preload improves both the fatigue resistance of a bolted connection and the locking effect. 螺栓预加载荷的重要性不能被过高地估计。较高预螺栓预加载荷的重要性不能被过高地估计。较高预载荷即提高螺栓联接的抗疲劳能力又改善锁紧作用。载荷即提高螺栓联接的抗疲劳能力又改善锁紧作用。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.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. 课文分析课文分析已经知道：高预载荷在重要的螺栓联接中是非常希已经知道：高预载荷在重要的螺栓联接中是非常希望的。下一步我们要考虑的是，当要装配零件时，望的。下一步我们要考虑的是，当要装配零件时，如何确保设计情况下该预载荷的产生。如何确保设计情况下该预载荷的产生。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.If the overall length L of a bolt with cross area A can actually be measured with a micrometer when it is assembled, the bolt elongation d due to the preload F can be computed using the formula d=FL/AE, where E is the modulus of elasticity of the bolt material. 课文分析课文分析如果横截面积为如果横截面积为A、总长度为、总长度为L的螺栓装配时，实的螺栓装配时，实际上是可以用千分尺来测量的，由于预载力际上是可以用千分尺来测量的，由于预载力F的作的作用而使螺栓伸长量为用而使螺栓伸长量为d，d可以利用公式可以利用公式dFLAE来计算，式中来计算，式中E是螺栓材料的弹性模量。是螺栓材料的弹性模量。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.Then simply tighten the nut until the bolt elongation through the distance d. This assures that the desired preload has been attained. 课文分析课文分析那么只要旋紧螺母直至使螺栓伸长达到那么只要旋紧螺母直至使螺栓伸长达到d。这就保证。这就保证了已经达到了所希望的预紧载荷。了已经达到了所希望的预紧载荷。 However, the elongation of a screw cannot usually be measured because the threaded end may be in a blind hole. 然而，螺钉的伸长量通常是不能测量的，因为螺钉然而，螺钉的伸长量通常是不能测量的，因为螺钉端部可能是在盲孔内。端部可能是在盲孔内。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.It is also impractical in many cases to measure bolt elongation. In such cases the wrench torque required to develop the specified preload must be estimated. 课文分析课文分析在许多情况下，去测量螺栓的伸长也是不切实际的。在许多情况下，去测量螺栓的伸长也是不切实际的。在这样情况下，能产生具体预载荷的扭矩扳手必须在这样情况下，能产生具体预载荷的扭矩扳手必须能测定出该预紧载荷。能测定出该预紧载荷。 Then torque wrenching, pneumatic-impact wrenching, or the turn-of-the-nut method may be used. 扭矩扳手，气动冲击扳手，或螺帽旋动圈数扳手法扭矩扳手，气动冲击扳手，或螺帽旋动圈数扳手法等可用于测定预载荷。等可用于测定预载荷。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.The torque wrench has a built-in dial, which indicates the proper torque. 课文分析课文分析扭矩扳手有一个内置式指示盘，以便显示正确的扭扭矩扳手有一个内置式指示盘，以便显示正确的扭矩。矩。 With impact wrenching the air pressure is adjusted so that the wrench stalls when the proper torque is obtained, or in some wrenches, the air automatically shuts off at the desired torque. 用冲击扳手时，要调节空气压力，当获得正确扭矩用冲击扳手时，要调节空气压力，当获得正确扭矩时，扳手即停止转动，或者有些气动扳手，当达到时，扳手即停止转动，或者有些气动扳手，当达到希望的扭矩时，压缩空气自动关掉。希望的扭矩时，压缩空气自动关掉。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.The turn-of-the-nut method requires that we first define the meaning of snug tight. 课文分析课文分析要使用螺母转动圈数法首先要求我们确定适度紧的要使用螺母转动圈数法首先要求我们确定适度紧的意义。意义。 The snug-tight condition is the tightness attained by a few impacts of an impact wrench, or the full effort of a man using an ordinary wrench. 适度紧的状态就是借助于冲击扳手冲击几次所达到适度紧的状态就是借助于冲击扳手冲击几次所达到的预紧度，或一个男人用普通扳手尽全力上紧的程的预紧度，或一个男人用普通扳手尽全力上紧的程度。度。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.Having attained the snug-tight condition, all additional turning develops useful tension in the bolt. 课文分析课文分析已经达到适度紧状态时候，所有的附加旋动会在螺已经达到适度紧状态时候，所有的附加旋动会在螺栓中产生有益张紧力。栓中产生有益张紧力。 The turn-of-the-nut method requires that one computes the fractional number of turns necessary to develop the required preload from the snug-tight condition. 旋动螺母圈数法要求；必须先旋动零点几转以便产旋动螺母圈数法要求；必须先旋动零点几转以便产生在适度紧基础上所要求的预紧载荷。生在适度紧基础上所要求的预紧载荷。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.For example, for heavy hexagon bolts the turn-of-the-nut specification states that the nut should be turned a minimum of 180 deg, from the sung-tight condition. 课文分析课文分析例如，对于重型六角头螺栓的旋转螺母圈数法的技例如，对于重型六角头螺栓的旋转螺母圈数法的技术要求称：螺母应从适度紧状态起最少旋动到术要求称：螺母应从适度紧状态起最少旋动到180度。度。 Note that this is also about the correct rotation for the wheel nuts of a passenger car. 注意这也是关于客车车轮螺母预紧的正确转数。注意这也是关于客车车轮螺母预紧的正确转数。 机械工程专业英语机械工程专业英语Lesson 19 Screws, fasteners and joints Evaluation only.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Copyright 2004-2011 Aspose Pty Ltd.