毕业设计机电专业英语文章.doc

数控车床及车削加工介绍(中英文对照) 1Lathes Lathes are machine tools designed primarily todoturning, facing and boring, Very little turning isdone onother types ofmachine tools, and none can doitwith equal facility. Because lathes also can dodrilling and reaming, their versatility permits several operations tobedone with asingle setup ofthe work piece. Consequently, more lathes ofvarious types are used inmanufacturing than any other machine tool. The ponents ofalathe are the bed, headstock assembly, tailstock assembly, and the leads crew and feed rod. The bed isthe backbone ofalathe. Itusually ismade ofwell normalized oraged gray ornodular cast iron and provides sheavy, rigid frame onwhich all the other ponents are mounted. Two sets of parallel, longitudinal ways, inner and outer, are contained onthe bed, usually onthe upper side. Some makers use aninverted V-shape for all four ways, whereas others utilize one inverted Vand one flat way inone orboth sets, They are precision-machined toassure accuracy ofalignment. Onmost modern lathes the way are surface-hardened toresist wear and abrasion, but precaution should betaken inoperating alathe toassure that the ways are not damaged. Any uracy inthem usually means that the accuracy ofthe entire lathe isdestroyed. The headstock ismounted inafoxed position onthe inner ways, usually atthe left end ofthe bed. Itprovides apowered means ofrotating the word atvarious speeds .Essentially, itconsists ofahollow spindle, mounted urate bearings, and aset oftransmission gears-similar to atruck transmission —through which the spindle can berotated atanumber ofspeeds. Most lathes provide from 8to18speeds, usually inageometric ratio, and onmodern lathes all the speeds can beobtained merely bymoving from two tofour levers. Anincreasing trend istoprovide acontinuously variable speed range through electrical ormechanical drives. Because the accuracy ofalathe isgreatly dependent onthe spindle, itisofheavy construction and mounted inheavy bearings, usually pre