机械类车床外文翻译
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1、毕业设计(论文) 外文翻译(原文) Lathe 来源: http:/en.wikipedia.org/wiki/Lathe A lathe is a machine tool which spins a block of material to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about
2、 an axis of rotation. Lathes are used in woodturning, metalworking, and glassworking. Lathes can be used to shape pottery, the best-known design being the potters wheel. Most suitably equipped metalworking lathes can also be used to produce most solids of revolution, plane surfaces and screw threads
3、 or helices. Ornamental lathes can produce three-dimensional solids of incredible complexity. The material is held in place by either one or two centers, at least one of which can be moved horizontally to accommodate varying material lengths. Examples of objects that can be produced on a lathe inclu
4、de cue sticks, table legs, bowls, baseball bats, crankshafts and camshafts. History The lathe is an ancient tool, dating at least to the Egyptians , and known and used in Greece, the Roman and Byzantine Empires. The origin of turning dates to around 1300BC when the Egyptians first developed a two-pe
5、rson lathe. One person would turn the wood workpiece with a rope while the other used a sharp tool to cut shapes in the wood. The Romans improved the Egyptian design with the addition of a turning bow. Early bow lathes were also developed and used in Germany, France and Britain. In the Middle Ages a
6、 pedal replaced hand-operated turning, freeing both the craftsmans hands to hold the woodturning tools. The pedal was usually connected to a pole, often a straight-grained sapling. The system today is called the spring pole lathe. Spring pole lathes were in common use into the early 20th Century. A
7、two-person lathe, called a great lathe, allowed a piece to turn continuously (like todays power lathes). A master would cut the wood while an apprentice turned the crank。 During the industrial revolution the lathe was motorized, allowing wooden turned items to be created in less time and allowing th
8、e working of metal on a lathe. The motor also produced a greater rotational speed, making it easier to quickly produce high quality work. Today most commercial lathes are computer-operated allowing for mass-production that can be created with accurate precision and without the cost of employing craf
9、tsmen. Description Parts of a lathe A lathe may or may not have a stand, which sits on the floor and elevates the lathe bed to a working height. Some lathes are small and sit on a workbench or table, and do not have a stand. Almost all lathes have a bed, which is (almost always) a horizontal beam (a
10、lthough some CNC lathes have a vertical beam for a bed to ensure that swarf, or chips, falls free of the bed). A notable exception is the Hegner VB36 Master Bowlturner, a lathe designed for turning large bowls, which in its basic configuration is little more than a very large headst At one end of th
11、e bed (almost always the left, as the operator faces the lathe) is a headstock. The headstock contains high-precision spinning bearings. Rotating within the bearings is a horizontal axle, with an axis parallel to the bed, called the spindle. Spindles are often hollow, and have exterior threads and a
12、n interior taper on the inboard by which accessories which hold the workpiece may be mounted to the spindle. Spindles may also have exterior threads and an interior taper at their outboard end, or may have a handwheel or other accessory mechanism on their outboard end. Spindles are powered, and impa
13、rt motion to the workpiece. The spindle is driven, either by foot power from a treadle and flywheel or by a belt drive to a power source. In some modern lathes this power source is an integral electric motor. Accessories Unless a workpiece has a taper machined onto it which perfectly matches the int
14、ernal taper in the spindle, or has threads which perfectly match the external threads on the spindle (two things which almost never happen), an accessory must be used to mount a workpiece to the spindle. A workpiece may be bolted or screwed to a faceplate, a large flat disk that m A workpiece may be
15、 clamped in a chuck, which mounts directly to the spindle or mounted on a mandrel. In precision work (and in some classes of repetition work), cylindrical workpieces are invariably held in a collet inserted into the spindle and secured either by a drawbar, or by a collet closing cap on the spindle.
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