1、毕 业 设 计（论 文）外 文 参 考 资 料 及 译 文译文题目： Lathe and Turning 车床与车削 学生姓名： 学 号： 专 业： 所在学院： 指导教师： 职 称： 20xx年 2月 27日Lathe and TurningThe Lathe and Its Construction A lathe is a machine tool used primarily for producing surfaces of revolution and flat edges.Based on their purpose, construction, number of tools t
2、hat can simultaneously be mounted, and degree of automation, lathes-or, more accurately, lathe-type machine tools can be classified as follows:(1)Engine lathes(2)Tool room lathes(3)Turret lathes(4)Vertical turning and boring mills(5)Automatic lathes(6)Special-purpose lathes In spite of that diversit
3、y of lathe-type machine tools, they all have common features with respect to construction and principle of operation. These features can best be illustrated by considering the commonly used representative type, the engine lathe. Following is a description of each of the main elements of an engine la
4、the. Lathe bed. The lathe bed is the main frame, involving a horizontal beam on two vertical supports. It is usually made of grey or nodular cast iron to damp vibrations and is made by casting. It has guide ways to allow the carriage to slide easily lengthwise. The height of the lathe bed should be
5、appropriate to enable the technician to do his or her job easily and comfortably. Headstock. The headstock is fixed at the left hand side of the lathe bed and includes the spindle whose axis is parallel to the guide ways (the slide surface of the bed). The spindle is driven through the gearbox, whic
6、h is housed within the headstock. The function of the gearbox is to provide a number of different spindle speeds (usually 6 up to 18 speeds). Some modern lathes have headstocks with infinitely variable spindle speeds, which employ frictional, electrical, or hydraulic drives. The spindle is always ho
7、llow; it has a through hole extending lengthwise. Bar stocks can be fed through that hole if continuous production is adopted. Also, that hole has a tapered surface to allow mounting a plain lathe center. The outer surface of the spindle is threaded to allow mounting of a chuck, a face plate, or the
8、 like. Tailstock. The tailstock assembly consists basically of three parts, its lower base, an intermediate part, and the quill. The lower base is a casting that can slide on the lathe bed along the guide ways, and it has a clamping device to enable locking the entire tailstock at any desired locati
9、on, depending upon the length of the work piece. The intermediate part is a casting that can be moved transversely to enable alignment of the axis of the tailstock with that of the headstock. The third part, the quill, is a hardened steel tube, which can be moved longitudinally in and out of the int
10、ermediate part as required. This is achieved through the use of a hand wheel and a screw, around which a nut fixed to the quill, is engaged. The hole in the open side of the quill is tapered to enable mounting of lathe centers or other tools like twist drills or boring bars. The quill can be locked
11、at any point along its travel path by means of a clamping device. The carriage. The main function of the carriage is mounting of the cutting tools and generating longitudinal and/or cross feeds. It is actually an H-shaped block that slides on the lathe bed between the headstock and tailstock while b
12、eing guided by the V-shaped guide ways of the bed. The carriage can be moved either manually or mechanically by means of the apron and either the feed rod or the lead screw. When cutting screw threads, power is provided to the gearbox of the apron by the lead screw. In all other turning operations,
13、it is the feed rod that drives the carriage. The lead screw goes through a pair of half nuts, which are fixed to the rear of the apron.When actuating a certain lever, the half nuts are clamped together and engage with the rotating lead screw as a single nut, which is fed, together with the carriage,
14、 along the bed. When the lever is disengaged, the half nuts are released and the carriage stops.The quick-change gearbox is employed in plain turning, facing and thread cutting operations. Since that gearbox is linked to the spindle, the distance that the apron (and the cutting tool) travels for eac
15、h revolution of the spindle can be controlled and is referred to as the feed.A modern lathe usually has a quick-change gearbox located under the headstock and driven from the spindle through a train of gears. It is connected to both the feed rod and the lead screw and enables selecting a variety of feeds easily and rapidly by simply shifting the appropriate levers. On the other hand, when the feed rod is used, it supplies power to the apron through a worm gear. The latter is keyed to the fee
