ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 1 Deformation Processing - Drawing ver. 1ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 2 Overview • Description • Characteristics • Mechanical Analysis • Thermal Analysis • Tube drawingME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 3 Geometry Da Db Fa, sxa Fb, sxb aME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 4ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 5 EquipmentME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 6 Cold DrawingME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 7 A. Durer - Wire Drawing Mill (1489) (copper wire)ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 8 Self portrait at 28 (1500) The four horsemen of the apocalypse (1498)ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 9 Characteristics • Product sizes: – 0.0002” (5mm) to several inches (100-150 mm) • Mostly cold (T < 0.4 Tmelting) – below recrystallization point • Small diameter (wire): – uses a capstan • Diameter > 1 inch (25 mm) (rod): – bull blocks on a draw bench – length up to 40 feet (12 m)ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 10 Characteristics • Fine wire done through several dies • Speeds – large diameter: 30 feet per minute (9 m/min) – small diameter: 300 feet per minute (90 m/min) – fine wires: 5,000 feet per minute (60 mph – 100 km/h)ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 11 Die Materials • Large diameter – high carbon steel – high speed steel • Moderate diameter – tungsten carbide (WC) • Small diameter – diamond insertsME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 12 Characteristics • Lubrication – Coatings – Oil • Die angle (a) – typically small: 4-6oME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 13 Mechanical analysis (round wire / rod) Reduction in area (RA) 22221bababDDDDDRAabtDDRAln211lnDa Db Fa, sxa Fb, sxb aME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 14 Slab analysis Assume p, sx are uniform – OK for small a, m sx + dsx sx p p mp mp D D + dD dxME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 15 Equilibrium 0coscossincos4422aamaasssdxDpdxDpDdDDdxxxExpanding 0coscossincos424222aamaasssdxDpdxDpDdDDdDDdxxxME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 16 Equilibrium 0coscossincos422422222aamaasssssssdxDpdxDpDdDdDdDdDddDDdDDxxxxxxxsmall small small Eliminating higher order terms, dividing by D & , multiplying by 4 and canceling 0coscos4sincos42 aamaassdxpdxpDddDxxME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 17 Equilibrium dxdD2tan aatan2dDdxNoting dx D dD/2 a 0tan2coscos4tan2cossin42 aaamaaassdDpdDpDddDxxor 0tan222 amssdDppdDDddDxxME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 18 Equilibrium 0tan122 dDpdDdDxxamssFinallyME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 19 Maximum shear stress (Tresca) criterion flo wflo wxpss 2Bamtanp sx flowME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 20 Differential form pBdpDdDflow24 BBdDdDflowxx142ssME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 21 Integrating xbxabaBBdDdDflowxxDDssss142ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 22 Drawing stress • where: sxb = back stress (tension) sxa = pulling stress (tension) BbaflowxbBbaflowxaDDDDBB222112ssDa Db sxa sxb aME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 23 12nKYnflowflowsStrain hardening (cold – below recrystallization point) • For round parts - Tresca average flow stress: due to shape of elementME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 24 Strain rate effect (hot – above recrystallization point) • For a round part (derived for extrusion) – average strain rate due to shape of element – vb = velocity of “b” side – A = area mflowflowCYs2ababbbAADDDvlntan6332aME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 25 Value for p p = Y – s or p = 2flow – s maximum at entrance p sx flowME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 26 Effect of back tension with back tension without back tension drawing stress entry exit die pressureME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 27 Maximum RA • Solve previous equations with: a = 6o (typical value) m = 0.1 B = 1 sxb = 0 For failure: draw stress = material flow {yield} stress here, say K = 760 MPa, and n = 0.19 12nKYnflowfl owsnxaKssME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 28 Maximum RA • Yields RA = 0.6 – must be solved for each m, a, sxb BbannDDBBnKK2111211111119.0baDDME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 29 Energy / unit volume (u) u = F V / Aa V = sxa (with no back stress) V= volumeME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 30 Drawing - Ex. 1-1 Determine power, and plot sx and p along die length. • Drawing steel rod from f = 13 mm to f = 12 mm @ 1.5 m/s • K = 760 MPa, n = 0.19 • m = 0.1, a = 4o, sxb = 0ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 31
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