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1、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,Slotted cone pointed set screw. Hex nut. Slotted nut . Bright washer. Spring washer. Tab washer 锥端紧定螺钉 六角螺母 六角槽形螺母 平垫圈 弹簧垫圈 外舌止动垫圈,Hexagon head bolt. Stud. Slotted cheese head screw. Slotted pan head screw. Slotted countersunk screw. Hexago
2、n socket cap 六角头螺钉 双头螺柱头 圆柱头螺钉 盘头螺钉 沉头螺钉 圆柱头内六角螺钉,Types of screw fasteners 螺纹紧固件的种类,Parts with threads used for joining and fastening are called screw fasteners. The most widely used components as screw fasteners are bolts, double screw bolts-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
3、螺纹紧固件有螺栓、双头螺柱、螺钉、螺母、垫圈等。,Lesson 19 Screws, fasteners and joints,机械工程专业英语,机械工程专业英语,预备知识,一、Background information,Lesson 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
4、 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
5、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
6、lock washers, thread adhesives, and lock nuts).,机械工程专业英语,预备知识,一、Background information,Lesson 19 Screws, fasteners and joints,Bolted joint,Screw joint,Stud joint,Bolt 螺 栓,The bolt assembly is used when joint parts are not too thick to drill through holes. 螺栓 用于联接二通孔薄件,Stud 双头螺柱,Stud are used in situ
7、ations where a part with a through hole and a part with blind tapped hole. 双头螺柱 用于联接一通孔薄件和一盲孔厚件。,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 多用于用于受力不大需要经常拆卸的情况,Nut 螺 母,Nut are used to match the other scre
8、w fasteners. 螺母 与其他螺纹件配合使用,Washer 垫 圈,弹簧垫圈 平垫圈,Washer are used to match the other screw fasteners. 垫圈 与其他螺纹件配合使用,机械工程专业英语,预备知识,一、Background information,Lesson 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 genera
9、lly 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
10、 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.,机械工程专业英语,预备知识,一、Background information,Lesson 19 Screws, fasteners and joints,Theory
11、 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
12、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.,机械工程专业英语,预备知识,一、Background information,Lesson 19 Screws, fasteners and join
13、ts,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, ex
14、tended 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) th
15、is analogy doesnt hold true. The load seen by the hardware is the preload plus the external load.,机械工程专业英语,预备知识,一、Background information,Lesson 19 Screws, fasteners and joints,机械工程专业英语,预备知识,一、Background information,Lesson 19 Screws, fasteners and joints,Theory The results of this type of joint desig
16、n 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 load
17、s 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.,
