23 bulk-deformation - ME250 Design and Manufacturing I Bulk...

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Bulk deformation processes ME250 Design and Manufacturing I
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2 Introduction Forging Extrusion Summary Outline
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3 Introduction Bulk deformation processes Stresses metals to plastically deform to a desired shape. Can be done cold, warm, or hot. Less or no waste. Near net or net shape process.
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4 Forging Forging processes Deform the metal between two dies to conform the die shape, using impact or gradual pressure (sometime under high temp.) Compression strengthen parts Usually flush is formed: need subsequent machining
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5 Forging Forged products
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6 Forging Forged products
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7 Forging Forging machine
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8 Forging Forging types open-die forging flushless forging impression-die forging
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9 Forging Force analysis of open-die forging Friction between work and die causes “barreling” Barreling as D/h (as contact area ) As forging proceeds, D , h , F F is maximum at completion
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10 Forging Required force for open-die forging Strain of work Flow stress of material K : strength coefficient n : strain hardening exponent Compression force A : contact area of work with die K f : shape factor = 1 + 0.4 m D / h : coefficient of friction 0 ln h h  n f YK ff F K Y A
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11 Example D 0 = 50 mm h 0 = 75 mm h f = 36 mm K = 350 MPa n = 0.7 m = 0.1 Assume = 0.002 at the moment of die contact Constant volume during compression No barreling effect to contact area A F [N] at h = 75, 62, 49, 36 [mm]? Forging D 0 h 0 h f
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12 Example At h = 75 [mm] Convenient tip: [MPa] X [mm 2 ] = [N] Forging 2 00 0 0 2 0.7 0.4 1 4 0.4 0.1 50 3.14 50 1 75 4 245410 [N] 245 [kN] n ff DD F K Y A K h m    at the moment of die contact
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13 Example At h = 62 [mm] Since 1) Constant volume during compression and 2) no barreling effect to contact area A, therefore Forging 2 2 00 0 0 0 0.4 1 4 0.4 / ( / ) 1 ln 4 649303 [N] 649 [kN] n ff n DD F K Y A K h h hD h h h D K hh m m
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This note was uploaded on 03/21/2010 for the course MECHENG 250 taught by Professor Stevis during the Fall '09 term at University of Michigan.

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23 bulk-deformation - ME250 Design and Manufacturing I Bulk...

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