EXPERIMENTAL ANALYSIS OF TUBE HYDROFORMING

Transcription

1 In. J. Mech. Eng. & Rob. Res. 4 B Anjaneya Reddy e al., 4 Research Paper ISSN Vol. 3, No., January 4 4 IJMERR. All Rghs Reserved EXPERIMENTAL ANALYSIS OF TUBE HYDROFORMING Bahna Sreenvasulu, B Anjaneya Reddy * and B Sreenvasulu *Correspondng Auhor: B Anjaneya Reddy, bvanj@gmal.com The Tube Hydroformng Process (THF) s a relavely complex manufacurng process; he performance of hs process depends on varous parameers lke nernal pressure, axal loadng ec. and requres proper combnaon of par desgn, maeral selecon and boundary condons. Due o he complex naure of he process, he behavour of hs processes are suded expermenally. Curren sudy nvolves expermenal work on ube hydroformng. Sudy on varous parameers of he ube hydroformng process o approach opmum process parameers. How dfferen maerals and process parameers nfluence he loadng pahs. The sudy was a par of a large nvesgaon. Keywords: Bulge formng, Tube hydroformng, Manufacurng process, Process parameer, Maerals, Bulge hegh INTRODUCTION Tube hydroformng s one of he bes processes o produce ubular componens of dfferen shapes, n hs process he ubes are formed no he shapes of he des by usng nernal pressure and axal force. There are so many applcaons of ube hydro formng n auomobles, aerospace, households, saonares, ec., all ypes of ducle maerals can be used for ube hydroformng process lke alumnum, copper, brass, sanless seel, alloy seel ec. Ths process ncludesmany dffcules such as loadng varables, whch s called desgn of loadng pahs and also nernal pressure. If any varaon n loadng pahs whch leads o process falures such as bucklng, wrnklng, bursng generally he flud used for ube hydroformng process s waer, here are somany advanages of hydroformng such as lke wegh reducon and hgh ulzaon of maeral srengh and also sffness. Inally he ube EN3of lengh 5 mm, dameer 57.5 mm and hckness.5 mm s placed beween he des and wo plungers are used o enclose he ends of he ube o preven leakage as well as o provde axal feedng of ubular maeral o manan same hckness afer deformaon and a nozzle s provded o allow pressurzed flud Deparmen of Mechancal Engneerng, Madanapalle Insue of Technology & Scence, Pos Box No: 4, Kadr Road, Angallu (V), Madanapalle

2 In. J. Mech. Eng. & Rob. Res. 4 B Anjaneya Reddy e al., 4 no he ube from a hydraulc un. Frcon should be mnmzed whle he formaon of ube n THF. The frcon s developed n beween he ubular maeral and he de. If more frcon s developed he axal force and nernal pressure requred s also hgh and a he same me we can expec good formably,.e., hckness and bulge hegh of ube. In hs curren sudy analycal model for free bulge formng was proposed and was shown ha for =.5 where s s so ha we can oban good correlaon beween expermenal and analycal model was obaned. The ube formably can be ncreased and pressure can be decreased when = s consdered. Fgure schemac llusraon of he ube end condons durng formng: ) Freeformng, ) Fxed end, 3) Forced end. Fgure 3: Tube Afer Bulgng Fgure 4: Sresses Acng a he Mddle of he Tube on an Elemen Fgure : Tube and De Seup Analycal model for free bulge formng was proposed and was shown ha when =.5 ( / ), good correlaon beween expermenal and analycal model can be obaned. Fgure : Tube Subjeced o Axal Force ANALYTICAL SOLUTION Assume when a ube s subjeced o an nernal pressure (P ) a he mddle of he ube for an elemen, he below equlbrum can be wren P...() Von msses yeld creron (plane sresses) and equvalen sran can wren as: 84

3 In. J. Mech. Eng. & Rob. Res. 4 B Anjaneya Reddy e al., 4 where and /...() 4 / 3/...(3)...(4) /...(5) The radal and angenal srans and can be wren as ln...(6) ln...(7) where and s nal and fnal ube wall hckness and s nsananeous ube wall hckness LEVY-MISSES FLOW RULE YIELDS (OR) = ( + )/( + )...(8) = ( )/( )...(9) Combnng Equaons (, and 4) gves P...() A he nerface beween elasc and plasc deformaon we can assume ha d /...()...() =...(3) Yeldng srengh of a maeral y = y...(4) where d s he ouer dameer of he ube and s he nal hckness of ube P y y /...(5) If = P y d y d...(6) Plasc Deformaon Assume ha he ube expands as shown n below Fgure. Ths assumpon means So ha p Combnng Sub. d / p...(7) Combnng Equaons () and (6) gves p...(8) d / If = k(n)...(9) Combnng eq. and wh eq., we ge n k P 4 / 3 d n...() d ln ln d...() Equaon (9) no Equaon () yelds 85

4 In. J. Mech. Eng. & Rob. Res. 4 B Anjaneya Reddy e al., 4 p n k d ln d d Assume now ha: n...()...(3) 3 Combnng Equaons (5), (7) and (4) we ge d...(4) d Fracure sran can be denoed as: f n r...(5) Fracure sran n hydroformng can be wren as r n ln d / f...(6) Combnng Equaon (6) and (4) yelds 4 de n ln 3 d d fr 4...(7) / 3 where d fr s he ube ouer dameer a fracure and fr s he ube wall hckness a fracure. Noe: d fr and fr yeld he dameer and wall hckness a he mddle of expanson zone. n Table, he ousde dameer of he ube (D) s 57.5 mm and wall hckness () s.5 mm, lengh s 5 mm. Table : Chemcal Composon of En-3 EN-3 C mn s s n mo p cr Maeral Properes The ensle properes for he En-3 paren meal and mxed maeral specmens are shown n Table, he ubular maeral s nally esed from he surface defecs and hen expermen was conduced for beer oupu resuls. Table : Mechancal Properes of En-3 Densy (Kg/m 3 ) 7.8 Tensle srengh (N/mm ) 75 Yeld srengh (N/mm ) 45 Modulus of elascy (N/mm ) 5 Expermenal Approach In hs sudy, all he se of expermens were conduced on ube hydroformng machne and he ype of hydroformng s free buldge hydroformng, s carred ou expermenally concenrang manly on some parameers lke pressure, axal feedng, me and fnally frcon ha has been generaed beween ube and Fgure 5: Sresses Acng a he Mddle of he Tube EXPERIMENTAL PROCEDURES Maeral Selecon The maeral seleced for expermenal procedure s En-3, s composon s gven 86

5 In. J. Mech. Eng. & Rob. Res. 4 B Anjaneya Reddy e al., 4 de.the maxmum allowable workng pressure of he machnes MPa and he maxmum allowable axal force s, kn. Expermenal Toolng and Procedure The expermenal oolng s based on he concep of freehydroformng ha was manufacured omplemen he ubebulge es shown n Fgure 6. I s composed of an upper de, alower de, and wo axal plungers. whle free formng, heube s subjec o axal compressve force F and an nernalpressure P. Fgure 7 shows he smplfed schemac ofexpermenal oolng. The expermenal procedure ncludes four sages: () Theubes are prepared for he expermens. The ubes are cu noproper lengh; () The ube s placed no he de, he des areclamped properly and he axal plungers are pushed for sealng; (3) Axalcompressve force s appled wh he correspondngnernal pressure under dfferen lnear sran pahs o he ube unl he ube has subjeced o bursng; (4) Thedeformaon of he ube surfaceclosely a he fracure pon s measured for hemajor srans e and mnor Table 3: Analycal and Expermenal Resuls srans e. And he values ofhe rue sran (, ) are ransformed. RESULTS AND DISSCUSION Numercal Analyss Resuls Bysolvng Equaons (3) and (4) smulaneously, maxmum bulge hegh and hcknessvaraon of he ube (n max bulge hegh poson) can beobaned. The resuls such are obaned s compared wh expermenaldaa resuls. As shown, for =.5, a goodcorrelaon beween expermenal Fgure 6: Tes Specmen Afer Bulgng Fgure 7: Tes Specmen ha are Subjeced o Falure Max. Buldge Hegh (Analycal) Max. Buldge Hegh (Expermenal) Pressure (MPa) Buldge Hegh Error (%)

6 In. J. Mech. Eng. & Rob. Res. 4 B Anjaneya Reddy e al., 4 resuls and analycal resulshas been acheved. I s also known ha for b = ( ), formably of ube s ncreased and lower nernal pressure s needed for formng he ube and hckness varaon wll ncrease. In order o nvesgae he effec of hardenng coeffcen (4) on he formably of he exruded ube, pressure assumed o be 56.4 MPa and he value of n were vared beween.-.3 and he correspondng bulge heghs were compared. The resulng ube expanson s shown n Fgure as shown, a larger hardenng coeffcen leads n a hgher expanson. And also, for a gven ncremen n n a greaer ncrease n formably was seen a hgher n value. Influence of Frcon Frcon s an mporan facor n he majory of formng operaons. A low frcon coeffcen s ofen desrable for formng process. To sudy he effec of frcon beween he de and ube surfaces, a hgher frcon coeffcen leads o a less expanson and huge hckness varaon. In oher words, we can say ha decreasng he frcon whch reflecs n an ncrease n he formably of ubes. Fgure 8: Influence of Bulge Hegh and Pressure Fgure 9: Bulge Hegh, Axal Movemen w.r. Tme Fgure : Axal Movemen Illusraed wh Pressure Fgure : Varaon of Bulge Hegh w.r. Axal Movemen 88

7 In. J. Mech. Eng. & Rob. Res. 4 B Anjaneya Reddy e al., 4 The above graph s clear ha by gradually ncreasng pressurehe bulge hegh goes on ncreasng upo 9.79 mm, he axal feedng of ubular maeral whch reduces he frcon beween ube and de, also reduces he nake pressure and pushes he maeral n he bulgng area of he ube. CONCLUSION As per he above expermen, expermenal and heorecal analyss resuls and relevan dscussons, he below conclusons are obaned: Sran hardenng coeffcen has he hgh nfluence on formably of he ube, so ha for formng of maerals wh hgher value of n, Lower nernal pressure s needed, bu change n hckness n hese maerals s hgher han ohers wh lower of n, f he frcon beween de walls and ube ncrease, leads n renen force on he conac surface of he ubular maeral, so maxmum ouer dameer decreases and hckness varaon ncreases. As shown n hs sudy, f gh olerances are requred on fnal hydroformed ube, sprng back should be conrolled n he process. Wh hgher frcon hgher nal hckness, lower deradus and lower yeldng sress, gh olerances can be obaned. Correlaon could be acheved beween expermenal and numercal resuls. The orecal analyss showed ha hn walled cylnder equaons were suable o solve ube hydroformng process. Lower nernal pressure was needed o form f b =.5, here s a beer correlaon beween expermenal and analycal resuls. REFERENCES. Alaswad A and Benyouns K Y (), Tube Hydroformng Process: A Reference Gude, Vol. 33, pp Djavanrood F and Ghesary M (8), Analycal and Numercal Analyss of Free Bulge Tube Hydroformng, Vol. 5, No. 8, pp Hossen Seyedkash S M and Valollah Panahzadeh R (3), Process Analyss of Two-Layered Tube Hydroformng wh Analycal and Expermenal Verfcaon, Vol. 7, No. (), pp Jeong Km Æ and Sung-Jong Kang (3) A Predcon of Bursng Falure n Tube hydroformng Processes Based on Ducle Fracure Creron, Vol., pp Jong Km, Woo-Jn Song and Beom-Soo Kang (9), Probablsc Modelng of Sress-Based FLD n Tube Hydroformng Process, Vol. 3, pp Loh-Mousav M and Bakhsh-Jooybar M (8), Improvemen of Formably n T- Shape Hydroformng of Tubes by Pulsang Pressure. 7. Nader Asnaf (999), Analycal Modellng of Tube Hydroformng, Vol. 34, pp Nahale Boudeau and PerrckMale co (), A Smplfed Analycal Model for Pos-Processng Expermenal Resuls from Tube Bulgng Tes: Theory, Expermenaons, Smulaons, Vol. 65, pp Nng Ren, He Yang and Me Zhan (3), Sran Dsrbuon Characerscs of Welded Tube n NC Bendng Process Usng Expermenal Grd Mehod, Vol. 66, pp

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