EFFECT OF BLANK RADIUS ON RADIAL STRESSES IN HYDROFORMING DEEP DRAWING PROCESS

Transcription

1 EFFECT OF BLNK RDIUS ON RDIL STRESSES IN HYDROFORMING DEEP DRWING PROCESS R.UDY KUMR Dep.of Mechanical Engineeing, Mahama Gandhi Insiue of Technology, Gandipe, Hydeabad ndha Padesh. India. bsac : This pape pesens evaluaion and effec of blank adius on adial sesses hough mahemaical fomulaions in hydofoming deep dawing pocess using caso oil medium. Hydaulic pessue can enhance he capabiliies of he basic deep dawing pocess fo making cups. In hydofoming deep dawing pocess, applying he hydaulic pessue on blank peiphey in adial diecion. I is obained hough he punch movemen wihin he fluid chambe, which is povided in punch and die chambes. These wo chambes ae conneced wih he bypass pah and i is povided in he die. Duing he pocess punch movemen wihin he fluid chambe he pessue is geneaed in fluid and i is dieced hough he bypass pah o blank peiphey, he fluid film is ceaed on he uppe and lowe sufaces of he blank and subsequenly educes ficional esisance and is o educe ensile sesses acing on he wall of he semi dawn blank. The blank is aking a cene place in beween blank holde and die suface wih suppoing of high pessuized viscous fluid. The adial sesses ae poduced in he blank in adial diecion due o punch foce applied on i, he shea sesses aced by viscous fluid on he boh sides of blank, so apply viscosiy phenomenon o his analysis. The adial sesses ae deemined in ems of viscosiy of caso oil, blank geomey and pocess paamees fo magnesium alloys. Keywods: adial sess, shea sess, deep dawing pocess, hydo foming, viscosiy. INTRODUCTION Hydofoming deep dawing is one of shee meal foming pocess o poduce seamless shells, cups and boxes of vaious shapes. In his foming pocess, addiional elemen such as fluid pessue is o be conibues posiively in seveal ways. mongs he advanages of hydaulic pessue foming deep dawing echniques, inceased deph o diamee aio s and educes hickness vaiaions of he cups fomed ae noable. In addiion, he hydaulic pessue is applied on he peiphey of he flange of he cup, he dawing being pefomed in a simulaneous push-pull manne making i possible o achieve highe dawing aio s hen hose possible in he convenional deep dawing pocess. Deep dawing is an impoan pocess used fo poducing cups fom shee meal in lage quaniies. In deep dawing a shee meal blank is dawn ove a die by a adiused punch. s he blank is dawn adially inwads he flange undegoes adial ension and cicumfeenial compession []. The lae may cause winkling of he flange if he daw aio is lage, o if he cup diamee-o-hickness aio is high. blank-holde usually applies sufficien pessue on he blank o peven winkling []. Radial ensile sess on he flange being dawn is poduced by he ension on he cup wall induced by he punch foce. Hence, when dawing cups a lage daw aios, lage adial ension ae ceaed on he flange and highe ensile sess is needed on he cup wall. Bending and unbending ove he die adius is also povided by his ensile sess on he cup wall. In addiion, he ension on he cup wall has o help o ovecome ficional esisance, a he flange and a he die adius. s he ensile sess ha he wall of he cup can wihsand is limied o he ulimae ensile sengh of he maeial, in he field of hydo fom deep dawing pocess he special dawing pocesses such as hydo-foming [3], hydomechanical foming [4], coune-pessue deep dawing [5], hydaulic-pessue- augmened deep dawing [6]. The pocess is an auomaic co-odinaion of he punch foce and blank holding foce, low ficion beween he blank and ooling as he high pessue liquid lubicaes hese inefaces and eliminaion of he need fo a complicaed conol sysem [7-]. The pessue on he flange is moe unifom which makes i easies o choose he paamees in simulaion. The pessue in he die caviy can be conolled vey feely and accuaely, wih he appoximae liquid pessue as a funcion of punch posiion, he pas can dawn wihou any scaches on he ouside of he pa and also obained in good suface finish, suface qualiy, high dimensional accuacy and complicaed pas. In he fluid assised deep dawing pocess he pessuized fluid seves seveal puposes ae suppos he shee meal fom he sa o he end of he foming pocess, hus yielding a bee fomed pa, delays he on se of maeial failue and educes he winkles fomaion. In his pape he adial sesses ae evaluaed in ems of viscosiy of fluid, blank geomey, and pocess paamees fo magnesium alloys and sudied using above pocess heoeically. The viscosiy phenomenon is consideed fo evaluaion of he pocess.. NOTTION p = Radius of punch cp = cone adius on punch d = adius of die opening Inenaional Jounal of pplied Reseach in Mechanical Engineeing (IJRME) ISSN: 3 595, Volume-, Issue-, 6

2 cd = cone adius on die = hickness of blank = adius of blank σ = adial sess σ ө = hoop sess dθ = Effec Of Blank Radius On Radial Sesses In Hydofoming Deep Dawing Pocess angle made by elemen a ob axis P h = blank holde pessue P = adial pessue of fluid = Shea sess acing by he fluid on each side of elemen = Toal Shea sess aced by he fluid on he Elemen d = widh of elemen = adial disance of blank elemen fom ob axis σ o = yield sess = Radial sess a die cone. d C = cleaance beween die and punch = d p (dy) = disance beween uppe suface of he blank elemen and blank holde (dy) = disance beween lowe suface of he blank elemen and die suface dy = disance mainained by blank elemen fom boh blank holde and die suface = shea sess aced by fluid on uppe suface of he blank elemen = shea sess aced by fluid on lowe suface of he blank elemen du = velociy of he blank elemen elaive o blank holde and die suface = dynamic viscosiy o absolue viscosiy o Viscosiy of fluid =, he oal shea sess acing by he fluid on he blank elemen h = heigh of he gap = hickness of fluid The adial sesses ae geneaed in he blank in adial diecion due o punch foce applied on i So hese sesses ae geneaed in cicula blank maeial duing in he hydofoming deep dawing pocess. The vaious sesses acing on he blank elemen duing he pocess is shown in fig.. Fo mahemaical modeling, evaluaion and effec of blank adius on adial sesses, le us conside a small elemen of blank d in beween blank holde and die suface in adial diecion a a disance fom he ob axis of he cicula blank wih in he fluid egion (fig..). The viscous fluid conac on he boh sides of blank elemen, due o his, he viscous foce is aced by fluid on he boh sides of he blank elemen. The oal shea sess acing by he fluid on he elemen = (i.e. shea sess is acing by he fluid on he each sides of elemen and i is same).then shea foce F is given by, F = x c Whee c = fluid conac aea Fig. Hydofoming Deep Dawing pocess 3. MTHEMTICL MODELING 3. Evaluaion and Effec of blank adius on Radial Sesses The Hydofoming deep dawing Pocess as shown in fig.. In his dawing Pocess, a high pessue is poduced in he fluid by he punch peneaion ino he fluid chambe. This pessuized fluid is dieced o he peipheal suface of he blank hough he bypass holes and also his high pessue fluid leak ou beween he blank and boh he blank holde and die. This ceaes a fluid film on uppe and lowe suface of he flange and subsequenly educes ficional esisance. Duing he pocess he shea sesses ae acing by fluid on he boh sides of semi dawn blank a a gap, which is povided beween he blank holde and die suface and he semi dawn blank is aking place a middle of he gap. The heigh of he gap is moe han he hickness of he blank. Fig.. Sesses acing on he elemen duing Dawing pocess pply he equilibium condiion in adial diecion, i.e. Ne foces acing on he elemen in he adial diecion equal o zeo. Inenaional Jounal of pplied Reseach in Mechanical Engineeing (IJRME) ISSN: 3 595, Volume-, Issue-, 7

3 F, Effec Of Blank Radius On Radial Sesses In Hydofoming Deep Dawing Pocess d d d () s, ae he wo pinciple sesses, he equaion is obain by using Tesca s yield cieia () Combined eq. () and eq. () d d d he hydofoming deep dawing pocess, he blank is aking place a middle of he gap. The effec of viscosiy phenomenon in his pocess as shown in below fig.3. Newon s law of viscosiy is inoduced o his pocess fo evaluaion of sesses in ems viscosiy, hen he sudy of effec of viscosiy of influence on hese sesses is incopoaed. Le us conside a small elemen of blank in beween blank holde and die suface wih in he fluid egion i.e gap. as shown in fig.3. Bu dy dy, because he blank elemen is aking place a middle of he gap d d Inegaing d d d d ln C (3) Whee C is consan, i is obained fom bounday condiion. Tha bounday condiion : a, Whee is he coefficien of ficion beween blank and boh he blank holde and die suface The bounday condiion is Sub. in eq. (3) we ge C ln Componen C is sub. in eq.(3) ln ( ) (4) This equaion (4) epesens mahemaical modeling and disibuion of adial sesses, effec of adius of blank on adial sesses duing he hydofoming deep dawing pocess. 4. PHENOMEN OF VISCOSITY In his hydofoming deep dawing pocess, he blank is ineacion wih he fluid, hen he viscosiy is comes ino he picue. Duing he pocess he shea sesses and shea foces ae acing by he fluid on he blank in he gap, which is he egion beween blank holde and die suface. Duing Fig.3.The blank elemen beween blank holde and die suface wihin he fluid egion Because dy dy dy dy h bu = du dy du dy, ccoding o du Newon s law of viscosiy =, dy du = dy Le us = = The oal shea sess acing by he fluid on he blank elemen = + = = = du Bu = dy = u, Whee du = u Inenaional Jounal of pplied Reseach in Mechanical Engineeing (IJRME) ISSN: 3 595, Volume-, Issue-, 8

4 = u h Effec Of Blank Radius On Radial Sesses In Hydofoming Deep Dawing Pocess du = = dy = 4 u h 4 u = = h (5 ) Now we have o deemine he adial sesses in ems of viscosiy, hen he sudy of effec of viscosiy of influence on hese sesses is incopoaed. 5. RDIL STRESSES EXPRESSED IN TERMS OF VISCOSITY We know ha adial sesses ae poduced in he blank a a adial disance is given by eq.4 ln ( 4 u and = we ge h (6) ln 4 u h ( ) a he end of he blank (i.e. edges), pu = (7) The equaion (6) epesens he effec of viscosiy of fluid on he mahemaical modeling and disibuion of adial sesses in he blank and also effec of blank adius on adial sesses duing hydofoming deep dawing pocess. 6. DESCRIPTION OF MGNESIUM LLOYS Magnesium is he highes of he commecially impoan meals, having a densiy of.74 gm/cm 3 and specific gaviy.74 (3% highe han aluminum alloys and 75% lighe han seel). Like aluminum, magnesium is elaively weak in he pue sae and fo engineeing puposes is almos always used as an alloy. Even in alloy fom, howeve, he meal is chaaceized by poo wea, ceep and faigue popeies. Sengh dops apidly when he empeaue exceeds C, so magnesium should no be consideed fo elevaed empeaue sevice. Is modulus of elasiciy is even less han ha of aluminum, being beween one fouh and one fifh ha of seel. Thick secions ae equied o povide adequae siffness, bu he alloy is so ligh ha i is ofen possible o use hicke secions fo he equied igidiy and sill have a lighe sucue han can be ) Inenaional Jounal of pplied Reseach in Mechanical Engineeing (IJRME) ISSN: 3 595, Volume-, Issue-, 9 obained wih any ohe meal. Cos pe uni volume is low, so he use of hick secions is geneally no pohibiive.fo engineeing applicaions magnesium is alloyed mainly wih aluminum, zinc, manganese, ae eah meals, and ziconium o poduce alloys wih high sengh o-weigh aios. pplicaions fo magnesium alloys include use in aicaf, missiles, machiney, ools, and maeial handling equipmen, auomobiles and high speed compue pas.on he ohe posiive side, magnesium alloys have a elaively high sengh-o-weigh aio wih some commecial alloys aaining senghs as high as 3 MPa. High enegy absopion means good damping of noise and vibaion. While many magnesium alloys equie enamel o lacque finishes o impa adequae connecion esisance, his popey has been impoved makedly wih he developmen of high puiy alloys. Fo his analysis wo ypes of Magnesium alloys consideed namely Z3B-O and Z6-F Magnesium alloy Z3B-O : composiion (%): 3.5 l,.6 Mn,.Zn and Tensile sengh 4MPa, Yield sengh 5MPa. Magnesium alloy Z6-F: composiion (%): 6.5l,.Zn and Tensile sengh 48MPa, Yield sengh Mpa. 7. RESULTS & DISCUSSION The adial sess disibuion in he blank duing he hydofoming deep dawing is given by eq.6 ln 4 u h ( ) The following pocess paamees and yield sess values of magnesium alloys ae consideed fo evaluaion and effec of blank adius on adial sesses of magnesium alloys wih given fluid fo successful fomaion of cup in hydofoming deep dawing pocess. p = 3 mm, cp = 4mm, d = 35mm, cd = 4mm, BH = 4 mm, c = 5 mm, Radial pessue of fluid = P, Punch speed (velociy of blank) u = mm/sec, h = 4 mm, hickness of blank = mm, adius of blank = mm,5mm,mm ype of maeials used: Magnesium alloys ype of fluid used: caso oil, viscosiy =.985N sec/ m Yield sess values ( ) of magnesium alloys: Z3B-O = 5 x 6 N/m Z6-F = x 6 N/m The evaluaion of values of Radial sesses ( ) in he blanks of magnesium alloys wih a given fluid a a adial disance fom ob axis fo a given adius of blanks a consan hickness of blanks

5 Effec Of Blank Radius On Radial Sesses In Hydofoming Deep Dawing Pocess as follows.subsiue he above values in above equaion we ge genealized equaion fo evaluaion of adial sesses duing he pocess wih espec o diffeen adius of blanks of magnesium alloys wih caso oil medium ae a consan hickness of blanks = mm. = mm ln.97 = 5mm 5 ln.975 = mm ln.97 The adial sesses of magnesium alloys ae pesened in fig. 4,5,6 a = mm wih diffeen adius of blanks = mm,5mm,mm wihin he ange of adial disance = 55mm o 95mm. Fom he figue, due o viscosiy of fluids, he shea sesses and shea foces ae aced on he blank suface duing he hydofoming deep dawing pocess. So he adial sesses ae deceases wih inceasing of he adial disance of he blank fom he ob axis. Radial sesses ae also depends up on pocess paamees, yield sess of alloys and fluid pessue. Radial sess ( N/m ).8x 8.6x 8.4x 8.x 8.x 8 8.x 7 6.x 7 4.x 7.x 7 Z3 - O Z6 - F Radial disance fom ob axis (mm) Fig.5. Radial sess disibuion in Magnesium alloys a = 5mm Fom fig.5 he magnesium alloys a = 5mm wih caso oil, he ange of adial sesses of Z6-F is 43.69N/m N/m and Z3B O is N/m N/m, he ode of adial sesses of magnesium alloys as Z3B-O < Z6-F.mong hese alloys, fo a low adial disance fom he ob axis of blank is 55mm, he adial sess is highe value in Z6-F and lowes value in Z3B-O..8x 8 Radial sess ( N/m ).6x 8.4x 8.x 8.x 8 8.x 7 6.x 7 4.x 7.x 7 Z3B - O Z6- F Radial disance fom ob axis (mm) Fig.4. Radial sess disibuion in Magnesium alloys a = mm Fom fig.4 he magnesium alloys a = mm wih caso oil, he ange of adial sesses of Z6-F is N/m N/m and Z3B O is n/m N/m, he ode of adial sesses of magnesium alloys as Z3B-O < Z6-F.mong hese alloys, fo a low adial disance fom he ob axis of blank is 55mm,he adial sess is highe value in Z6-F and lowes value in Z3B-O. Radial sess ( N/m ).6x 8.4x 8.x 8.x 8 8.x 7 6.x 7 4.x 7.x 7 Z3B - O Z6 - F Radial disance fom ob axis (mm) Fig.6. Radial sess disibuion in Magnesium alloys a = mm Fom fig.6. he magnesium alloys a = mm wih caso oil, he ange of adial sesses of Z6-F is N/m N/m and Z3B O is N/m N/m, he ode of adial sesses of magnesium alloys as Z3B-O < Z6-F.mong hese alloys, fo a low adial disance fom he ob axis of blank is 55mm,he adial sess is highe value in Z6-F and lowes value in Z3B-O. Compaing he above esuls a case oil wih espec o adius of blanks, he ode of adial sesses as mm 5mm mm Inenaional Jounal of pplied Reseach in Mechanical Engineeing (IJRME) ISSN: 3 595, Volume-, Issue-,

6 8. CONCLUSIONS Effec Of Blank Radius On Radial Sesses In Hydofoming Deep Dawing Pocess The Radial sesses ae he funcion of pocess paamees, yield sess of magnesium alloys and viscosiy of case oil. The adial sesses ae deceases wih inceasing of he adial disance of he blank fom he veical ob axis. The adial sesses ae inceases wih inceasing he adius of blank of magnesium alloys. These effecs ae due o viscosiy of caso oil aced on he blanks of magnesium alloys duing he foming pocess. The adial pessue of fluid acing on blank suface of alloys is equal o blank holding pessue is o fo unifom defomaion of blank duing he pocess. The winkling is educed in blank due o he blank suppoed by high pessuized viscous fluid. Radial sesses of magnesium alloys ae deemined wih in he ange of is 55mm 95mm wih caso oil. Fo = mm, a = 55mm he highes value of adial sess occued in Z6-F is N/m, lowes value occued in Z3B- is N/m. Fo = 5mm, a = 55mm he highes value of adial sess occued in Z6-F is N/m, lowes value occued in Z3B- O is N/m. Fo = mm, a = 55mm he highes value of adial sess occued in Z6-F is N/m, lowes value occued in Z3B-O is N/m. The pecenage of deceases of adial sess fo hese magnesium alloys a = mm is 78.8%, = 5mm is 74% and = mm is 7%.The deceased amoun of adial sesses in magnesium alloys wih in he ange is 55-95mm, in Z3B-O is N/m and in Z6-F is N/m. So among he ode of decease amoun in adial sesses of magnesium alloys as Z3B- < Z6 F. The adial sesses ae in he magnesium alloys ae high a is 55mm, low a is 95mm and adial sesses ae zeo a is equal o blank adius (a edges of blank ). So he adial sesses ae invesely popoional o he adial disance of he blank fom he ob axis wee obained. The adial sesses ae diecly popoional o he adius of blanks ae obained. The adial sesses ae depends on he viscosiy, fluid pessue and pocess paamees. The highe values of adial sesses ae gives he minimizing he dawing ime and highe in foming limis. These adial sesses ae used o ge bee esuls of fomabiliy of magnesium alloys. CKNOWLEDGEMENT The auho (D.R.Uday Kuma) hanks he managemen and pincipal of Mahama Gandhi Insiue of Technology fo encouaging and ganing pemission o cay ou his wok. REFERENCES []. J.M. lexande, n appaisal of he heoy of deep dawing, Me. Rev. 5 (9) (96) []. D.F. Eay, E.. Reed, Techniques of Pess-woking Shee Meal, penice-hall, New Jesey, 974, pp. 7. [3]. W. Panknin, W. Mulhause, Pinciples of he hydo fom pocess, Mileilungen de foschungges Blechveebeiung 4 (957) [4]. B. Lasen, Hydomechanic foming of shee meal, Shee Me.Ind. (Feb. 977) [5]. K. Nakamua, Shee meal foming wih hydaulic coune pessue in Japan, nn. CIRP 36 () (987) [6]. S. Thiuvaudchelvan, novel pessue augmened hydaulic-deep-dawing pocess fo high daw aios, J. Mae. Poc.Technol. 54 (995) [7]. K. Lange, Handbook of Meal foming, McGaw-Hill, New Yok, 985, pp...4. [8]. S. Yossifon, J. Tiosh, on he pemissible fluid-pessue pah in hydofoming deep dawing pocesses analysis of failues and expeimens, Tans. SME J. Eng. Ind. (988) [9]. S. Thiuvaudchelvan, W. Lewis, noe on hydo foming wih consan fluid pessue, J. Mae. Pocess. Technol. 88 (999) []. K. Obelande, The hydomechanical deep dawing of shee meals-ii, Blech Rohe Pofile 4 (98) []. D.Y. Yang, J.B. Kim, D.W. Lee, Invesigaions ino he manufacuing of vey long cups by hydomechnical deep dawing and ioning wih conolled adial pessue, nn. CIRP 44 (995) []. S.H. Zhang, J. Dancke, Developmen of hydo-mechanical deep dawing, J. Mae. Pocess. Technol. 83 (998) 4 5. Inenaional Jounal of pplied Reseach in Mechanical Engineeing (IJRME) ISSN: 3 595, Volume-, Issue-,