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Taiyuan University of Technology Sheet Metal Forming Processes and Die Design 冲冲冲冲冲冲冲冲冲 College of Materials Science and Engineering Lecturer 冲 CAO Xiao-qing 冲冲冲冲冲 March,2009 Chapter Buldging and Flanging Main contents: Flanging of a hole (dimpling) Flanging of outer edge; Bulging(expanding) and local forming Key points: Deformation feature of bulging and hole flanging New Words: Flanging/dimpling （（（（ , buldging （（（（ , press （（（（（（ formability （（（（（ ferrous metal （（（（（ / （（（（（ non-ferrous metal （（（（（（ non-metallic materials （（（（（（（ cutting process( （（（（（ , forming (plastic deformation)process （（（（（（ §6.1 Flanging Definition and classification Flanging of a hole Flanging of outer edge Ironing flanging 1.Definition and classification definition: plane sheet(semi-product) →vertical edge along certain straight line or curve via flanging die classification: flanging of a hole and flanging of outer edge 2.Flanging of a hole A hole is drilled or punched and the surrounding metal is expanded into a flange 2.1 Deformation feature deformation zone: a ring of D-d εθ (+) > ε ρ (−),σ θ (+ ),σ ρ (+) risky section : edge fracture(βtype: local extension is not enough) 2.2 Deformation degree flanging coefficient: m=d/D limit flanging coefficient[m]: maximum deformation degree of no fracture 2.Flanging of a hole Phases in the procwss of flanging of a hole 2.Flanging of a hole factors affecting [m]: material’s property;: ε↑[m]↓ relative thickness: d0 / t↓[m]↓ state of edge: smooth[m]spherical[m] shape of hole: circular[m]>un-circular[m] 2.Flanging of a hole 2.3 Calculation of blank principle: neutral line length is constant punching hole in plane sheet: calculate the diameter of pre-punched hole from the size of workpiece ,then check it with [m] calculate Hmax using [m],then compare with Hworkpiece punching hole in the bottom of drawing work-piece 2.4 Flanging force estimate using empirical formula 2.Flanging of a hole 2.5 Determination of flanging die 2.Flanging of a hole 3.Convex-shrink flange Shrinkage : wrinkle , σ θ (−), ε = b /( R + b) Tension : edge fracture, σ (+ ), ε = b /( R − b) θ Blank calculating principle: constant neutral line length 4.Ironing flanging Blank calculating principle : constant volume Difference between general flanging and ironing flanging §6.2 Bulging and local forming Bulging Local forming 1.Bulging 1.1 Deformation feature deformation region: stable (