金属切削外文翻译

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1、METALCUTTINGTheimportanceofmachiningprocessescanbeemphasisedbythefactthateveryproductweuseinourdailylifehasundergonethisprocesseitherdirectlyorindirectly.(1)InUSA,morethan$100billionsarespentannuallyonmachiningandrelatedoperations.(2)Alargemajority(above80%)ofa

2、llthemachinetoolsusedinthemanufacturingindustryhaveundergonemetalcutting.(3)Anestimateshowedthatabout10to15%ofallthemetalproducedinUSAwasconvertedintochips.Thesefactsshowtheimportanceofmetalcuttingingeneralmanufacturing.Itisthereforeimportanttounderstandthemeta

3、lcuttingprocessinordertomakethebestuseofit.Anumberofattemptshavebeenmadeinunderstandingthemetalcuttingprocessandusingthisknowledgetohelpimprovemanufacturingoperationswhichinvolvedmetalcutting.AtypicalcuttingtoolinsimplifiedformisshowninFig.7.1.Theimportantfeatu

4、restobeobservedarefollows.1.Rakeangle.Itistheanglebetweenthefaceofthetoolcalledtherakefaceandthenormaltothemachiningdirection.Highertherakeangle,betteristhecuttingandlessarethecuttingforces,increasingtherakeanglereducesthemetalbackupavailableatthetoolrakeface.T

5、hisreducesthestrengthofthetooltipaswellastheheatdissipationthroughthetool.Thus,thereisamaximumlimittotherakeangleandthisisgenerallyoftheorderof15°forhighspeedsteeltoolscuttingmildsteel.Itispossibletohaverakeanglesatzeroornegative.2.Clearanceangle.Thisistheangle

6、betweenthemachinedsurfaceandtheundersideofthetoolcalledtheflankface.Theclearanceangleisprovidedsuchthatthetoolwillnotrubthemachinedsurfacethusspoilingthesurfaceandincreasingthecuttingforces.Averylargeclearanceanglereducesthestrengthofthetooltip,andhencenormally

7、anangleoftheorderof5~6°isused.Theconditionswhichhaveanimportantinfluenceonmetalcuttingareworkmaterial,cuttingtoolmaterial,cuttingtoolgeometry,cuttingspeed,feedrate,depthofcutandcuttingfluidused.Thecuttingspeed,v,isthespeedwithwhichthecuttingtoolmovesthroughthew

8、orkmaterial.Thisisgenerallyexpressedinmetrespersecond(ms-1).Feedrate,f,maybedefinedasthesmallrelativemovementpercycle(perrevolutionorperstroke)ofthecuttingtoolinadirectionus