机械类数控车床外文翻译外文文献英文文献车床.pdf

Lathes

Lathesaremachinetoolsdesignedprimarilytodoturning,facingandboring,Verylittleturningis

doneonothertypesofmachinetools,andnonecandoitwithequalfacility.Becauselathesalsocando

drillingandreaming,theirversatilitypermitsseveraloperationstobedonewithasinglesetupofthework

piece.Consequently,morelathesofvarioustypesareusedinmanufacturingthananyothermachinetool.

Theessentialcomponentsofalathearethebed,headstockassembly,tailstockassembly,andthe

leadscrewandfeedrod.

Thebedisthebackboneofalathe.Itusuallyismadeofwellnormalizedoragedgrayornodularcast

ironandprovidessheavy,rigidframeonwhichalltheotherbasiccomponentsaremounted.Twosetsof

parallel,longitudinalways,innerandouter,arecontainedonthebed,usuallyontheupperside.Some

makersuseaninvertedV-shapeforallfourways,whereasothersutilizeoneinvertedVandoneflatwayin

oneorbothsets,Theyareprecision-machinedtoassureaccuracyofalignment.Onmostmodernlathesthe

wayaresurface-hardenedtoresistwearandabrasion,butprecautionshouldbetakeninoperatingalatheto

assurethatthewaysarenotdamaged.Anyinaccuracyinthemusuallymeansthattheaccuracyoftheentire

latheisdestroyed.

Theheadstockismountedinafoxedpositionontheinnerways,usuallyattheleftendofthebed.It

providesapoweredmeansofrotatingthewordatvariousspeeds.Essentially,itconsistsofahollow

spindle,mountedinaccuratebearings,andasetoftransmissiongears-similartoatruck

transmission—throughwhichthespindlecanberotatedatanumberofspeeds.Mostlathesprovidefrom8

to18speeds,usuallyinageometricratio,an