金属轧制.ppt

FundamentalofMaterialsing,-RollingofMetals金属轧制,Rolling轧制,Rollingistheprocessofreducingthethicknessorchangingthecross-sectionofalongworkpiecebycompressiveforcesappliedthroughasetofrollsFig.13.1;轧制是通过一些轧辊对一个长坯料进行加压使其厚度减薄或者界面形状发生变化的工艺。,Theprocessissimilartotherollingofdough面团）witharollingpin（擀面杖）toreduceitsthickness.Rolling,whichaccountsforabout90ofallmetalsproducedbymetalworkingprocesses,wasfirstdevelopedinthelate1500s.Thebasicoperationisflatrolling.扁平孔型轧制,orsimplyrolling,wheretherolledproductsareflatplateandsheet.,Sheetsaregenerallylessthan6mmthick.Theyareusedforautomobileandaircraftbodies,appliances仪表,foodandbeverages饮料）containers,andkitchenandofficeequipment.,appliances,Theextrusiondieisasteeldiskwithanopening,thesizeandshapeoftheintendedcross-sectionofthefinalextrudedproductasindicatedbelow.,Flat-andShape-RollingProcesses,Figure13.1Schematicoutlineofvariousflat-andshape-rollingprocesses.SourceAmericanIronandSteelInstitute.,Slab钢板Hotstrip热轧带钢Pickling酸洗oiling润滑,skelp制管钢板Pickling酸洗oling润滑,bloom钢锭rail铁轨Tuberounds,Platest6mmSheetst0,andso|ex||ez|.Hence,atensionstressisgeneratedattheedges,tomakethelengthattheedgeequaltothatatthecenter.Thiscausesedgecracking,speciallyifductilityislow.Alligatoringoccursbyacomplexprocess.Aidedbydefectsintheoriginalcasting.,RESIDUALSTRESSES,Smallerrollstendtoworkthemetalatthesurfaces.Themetalextendsonthesurface.Asthematerialcomesoutoftherolls,thecentralbulkregionputstheextendedsurfaceincompression.Thisissimilartowhatoccursduringshotpeening.Largediameterrollsoftenusedinhotrollingtendtoworkthecentralregionmorethanthebulk.Thisisbecauseofhigherfrictionatthesurfaces.Consequently,thematerialislongerinthebulkthanthesurface,andatensionstressisgeneratedatthesurface.,FLATROLLINGPRACTICE,UseofFlatteningRolls,VariousRollArrangements,SendzimirMillforColdRollingofThinSheetsofHighStrengthMaterials,SHAPEROLLING,RINGROLLING,THREADROLLING,计算机在塑性成形加工中的应用,