机械工程专业英语课件.ppt

《机械工程专业英语课件.ppt》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、机械工程专业英语EnglishInMechanicalEngineeringCollegeofMechanicalEngineeringChongqingUniversity34Laser-AssistedMachiningandCryogenicMachiningTechniqueTomeetthedemandforproductionandprecision，researchersandequipmentbuildersarelookingoutsidetheboundsofconventionalmilling，drilling，turning，and

2、grinding.Newcuttingandmachiningprocessescontinuetoemergealongwithmethodsformodifyingtheconventionaltechniques.34Laser-AssistedMachiningandCryogenicMachiningTechniqueLaser-assistedmachining.Laser-assistedmachiningisaprocessthathaslongbeenresearchedandnowreadytocomeoutthelab.Inthisop

3、eration,alaserbeamisprojectedontothepartthroughfiberopticsorsomeotheroptical-beamdeliveryunit,justaheadofthetool(asshowninFig.34.1).Duringacut，laserpowerisvariedtomatchtheprofilebeingcut.CO2laserareusuallyusedwithpowerlevelsfrom200to500W.Thelaser-inducedheatsoftenstheworkpieceandmak

4、eiteasiertocut.34Laser-AssistedMachiningandCryogenicMachiningTechniqueThisprocesscanbeusedforverydiffcult-to-machinematerialssuchassuperalloyorceramics.Forexample，suchprocessyoucancutthroughceramicslikebutter.Italsooffersalowsurfaceroughness，usually0.5uminRaorbetter.34Laser-Assiste

5、dMachiningandCryogenicMachiningTechniqueBecausetheheatinglaserbeamistightlyfocused，heatingislocalizedaroundtheactualcuttingzone.Heatiscarriedoffinthechipsandtherearenochangesinthephysicalpropertiesofthematerialcutduetoheat.Therearetwoproblemswiththeprocess.Thereisaphysicalproblemin

6、itiallyofestablishingthecuttingparameters（laserpowerandfocus，cuttingspeedsandfeeds，etc.）andthepsychologicalproblemofconvincingpeopleitworkswellandhasmanyadvantages.34Laser-AssistedMachiningandCryogenicMachiningTechniqueCryogenicmachiningtechnique.Anuniqueuseofliquidnitrogenisofferi

7、ngamodificationoftraditionalturningtoimprovemanufacturingoperations.Using-195Cliquidnitrogenasacoolanttolowertheheatinthecuttingzoneoffersanumberofadvantages.Thecryogeniccoolantsystemdeliversajetof-195Cliquidnitrogendirectlytotheinsertduringturningoperations（asshowninFig.34.2）.34Las

8、er-AssistedMachinin