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1、数控车床及车削加工介绍（中英文对照）1 LathesLathes are machine toolsdesigned primarilyto do turning,facingandboring, Very little turningis done onother types ofmachine tools, andnone can do it with equal facility. Because lathes also can do drillingand reaming, theirversatilitypermitsseveraloperationsto be done witha
2、 single setup of the work piece. Consequently, more lathes of various types are used in manufacturing than any other machine tool.The essential components of a lathe are the bed, headstock assembly, tailstock assembly, and the leads crew and feed rod.The bed is the backbone of a lathe. It usually is
3、 made of wellnormalized or aged grayor nodular castiron and providess heavy, rigidframe on which all the other basic components are mounted. Two sets of parallel, longitudinal ways, inner and outer, are contained on the bed, usually on the upper side. Some makers use an inverted V-shape for all four
4、 ways, whereas others utilize one inverted V and one flat way in oneor both sets, They are precision-machined to assure accuracy of alignment. On most modern lathes the way are surface-hardened to resist wear and abrasion, but precaution should be taken in operating a lathe to assurethat the ways ar
5、e not damaged. Any inaccuracy in them usually means that the accuracy of the entire lathe is destroyed.The headstock is mounted ina foxed positionon the innerways, usuallyat the left end of the bed. It provides a powered means of rotating theword at various speeds . Essentially, it consists of a hol
6、low spindle,mounted in accuratebearings,and a setof transmissiongears-similar toa trucktransmissionthroughwhich the spindlecan be rotatedat a numberof speeds. Most lathesprovidefrom 8 to 18 speeds, usuallyina geometricratio,and on modern lathes allthe speeds can be obtainedmerely by movingfrom two t
7、o four levers.An increasingtrend isto providea continuouslyvariable speed range through electrical or mechanical drives.Because the accuracy of a latheis greatlydependent on the spindle,it is of heavy construction and mounted in heavy bearings, usuallypreloadedtaperedrolleror balltypes.The spindleha
8、s a hole extendingthrough its length, through which long bar stock can be fed. The size of maximum size of bar stock that can be machined when the material must be fed through spindle.The tailsticdassembly consists,essentially,of three parts.A lowercasting fits on the inner ways of the bed and can s
9、lide longitudinallythereon, with a means for clamping the entire assembly in any desiredlocation, An upper casting fits on the lower one and can be movedtransversely upon it,on some type of keyed ways, topermit aligning theassembly is the tailstockquill.This is a hollow steelcylinder,usuallyabout 51
10、 to 76mm(2to 3 inches) in diameter, that can be moved severalinches longitudinally in and out of the upper casting by means of a handwheel and screw.The size of a latheis designated by two dimensions. The firstis known as the swing. This is the maximum diameter of work that can berotated on a lathe.
11、 It is approximately twice the distance between theline connecting the lathecenters and the nearestpoint on the ways, Thesecond size dimension is the maximumdistancebetween centers.The swingthus indicates the maximumwork piece diameter thatcan be turned in thelathe, while the distance between center
12、s indicates the maximum length of work piece that can be mounted between centers.Engine lathes are the type most frequently used in manufacturing. They are heavy-duty machine tools with all the components described previously and have power drive for all tool movements except on the compound rest.Th
13、ey commonly range in size from 305 to 610 mm(12 to 24 inches)swing andfrom 610 to 1219 mm(24 to 48 inches) center distances, but swings up to1270 mm(50 inches) and center distances up to 3658mm(12 feet) are notuncommon.Most have chip pans and a built-incoolantcirculatingsystem.Smaller engine lathes-
14、with swings usually not over 330 mm (13 inches ) also are available in bench type, designed for the bed to be mounted on a bench on a bench or cabinet.Althoughengine lathesareversatileand very useful,because ofthetime requiredfor changingand settingtoolsand formaking measurementson the work piece, t
15、hy are not suitable for quantity production. Oftentheactual chip-productiontineislessthan30%ofthe totalcycle time.Inaddition,a skilled machinistisrequiredfor alltheoperations,andsuch persons are costly and often in short supply. However, much of theoperators time is consumed by simple, repetitious adjustments and inwatchingchips being made. Consequently,
