Lesson 19 Screws, fasteners and joints 机械工程专业英语 教学课件.pptVIP

English for Mechanical Engineering 机械工程专业英语 Jumbo jets such as Boeing’s 747 and Lockheed’s 1011 require as many as 2.5 million fasteners, some of which cost several dollars apiece. 课文分析 大型喷气发动机客机像被音747和洛克希德1011，需要250万个紧固件，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747，大约需要装70000个钛合金紧固件，全部大约要花150000美元；400000个具有精密公差的其他紧固件，大约要花250000美元；和30000个挤压用铆钉，安装后每个价值50美分。 机械工程专业英语 Lesson 19 Screws, fasteners and joints To keep cost down, Boeing, Lockheed, and their subcontractors constantly review new fastener designs, installation techniques, and tooling. 课文分析 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。 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，增长的价值那将像坐上喷气式飞机一样。 机械工程专业英语 Lesson 19 Screws, fasteners and joints [pr?u5lif?reit]vi. 激增; 繁殖; 增生 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 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。 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栓。 机械工程专业英语 Lesson 19 Screws, fasteners and joints 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 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。 机械工程专业英语 Lesson 19 Screws, fasteners and joints 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 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，另一端再装上螺帽。 It is the intent, rather