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1、4/22/20244/22/20241 1橘皮與裂痕橘皮與裂痕輕微裂痕小量模具痕跡4/22/20244/22/20242 2小量模具痕跡模具痕跡模具痕跡Tool Mark4/22/20243Locates the bend center lineDecreases formability of stripScores must extend all the way from edge to edgeScores that go too deep will cause crackingPre-Scoring 預壓痕預壓痕4/22/20244/22/20244 4Pre-ScoringuPoten
2、tial problems:Cracking from deep score and coiningScore not extending to edge,stress riser resulted in fatigue failure4/22/20244/22/20245 5CoiningCoining-Thickness Reductiont4/22/20244/22/20246 6CoiningCoining-Thickness Reduction Unintended Punch Bottoming Unintended Punch Bottoming Precise Location
3、 of Bends Precise Location of Bends Increase R/t Increase R/t Provide“knife-edge”Provide“knife-edge”Local Increase in Strength Local Increase in Strength4/22/20244/22/20247 7Coining Effect4/22/20248Coining Effect4/22/20244/22/20249 9Coining Effect4/22/20244/22/20241010CoiningIncreases Strength-Sligh
4、tlyDecreases Ductility-GreatlyDecreases Formability-GreatlyIncreases Stress Relaxation-ModeratelyDecreases Dimensional Stability-Slightly4/22/20244/22/20241111CoiningCoining-Problems in Areas WithHigh StressLarge DeflectionsModerate Forming RequirementsHigh Dimensional Accuracy4/22/20244/22/20241212
5、Springback Caused by residual compressive stress on the inside of the bend Caused by residual compressive stress on the inside of the bend and tensile stress on the outside of the bendand tensile stress on the outside of the bend Springback increases with the bend radius and with the yield Springbac
6、k increases with the bend radius and with the yield strengthstrength Thicker gages and higher elastic moduli decrease springbackThicker gages and higher elastic moduli decrease springbackCompressive StressTensileStressResultant Torsional(Straightening)Stress4/22/20244/22/20241313Controlling Springba
7、ck Overbend and allow to springback into desired shapeOverbend and allow to springback into desired shape Alternatively,Coining(“Hip-up”,or“Hit-forming”)reduces springback Alternatively,Coining(“Hip-up”,or“Hit-forming”)reduces springback(adds compressive stress to side in tension)(adds compressive s
8、tress to side in tension)The required“Hit-forming ratio H”to material thickness The required“Hit-forming ratio H”to material thickness is dependent upon the R/t value of the forming punch tip.is dependent upon the R/t value of the forming punch tip.Caution:May make bend susceptible to crackingCautio
9、n:May make bend susceptible to crackingHRt0.10.20.30.4 0.55101520H%R/t4/22/20244/22/20241414K=AK=Af f/A/A0 0=-25.54X=-25.54X3 3+17.91 X+17.91 X2 2 5.85X+1.08 5.85X+1.08 X=(YS/E)(R/t)X=(YS/E)(R/t)YS=yield strength,E=Elastic Modulus,R=punch YS=yield strength,E=Elastic Modulus,R=punch radiusradius t=th
10、icknesst=thicknessR0RfAtAfA04/22/20244/22/20241515試片1成形變薄T1 vs T2T1T24/22/20244/22/20241616試片1小量模具痕跡in ID of Bend4/22/20244/22/20241717試片2OD 試片2橘皮但無裂痕4/22/20244/22/20241818試片2非常輕微的模具痕跡on OD4/22/20244/22/20241919試片2折彎處幾乎沒有變薄4/22/20244/22/20242020試片2沒有模具痕跡in ID of Bend4/22/20244/22/20242121試片2沒有模具痕跡in ID of Bend
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客服电话：0574-28810668 投诉电话：18658249818
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