NGHIEN c d u - TRAO OPi
NGHIEN COU XAY D U N G
QUI TRINH TAO HINH ISF T R £ N TAM NHl/A PVC
Nguyen Van Nang', Nguyin Thanh Nam'
Nguyin Thiln Binh', Nguyin Thi Hiing', Ll Khdnh Diln^
' Phdng Thi nghiem Dilu khiln sd vd Ky thudt he thdng, Trddng Dai hpc Bdch khoa TP Hd Chi Minh ' Bd mdn Thilt kl Mdy Khoa Co khi, Trddng Dai hpc Bdch khoa TP Hd Chi Minh
T6M TAT
Cdng nghi biln dang cue bd lien tyic ISF Id mot cdng nghe tiem ndng trong linh vUc tao mau nhanh trin vdt lieu tdm. Bdi bdo tap trung nghiin cUu thilt lap qui trinh gia cdng tao hinh tdm biln dang CVLC bd lien tuc ISF trin tdm vdt lieu PVC cd gia nhiet, dng dung trong cdc nghien cvtu thUc nghiem tao hinh ddi vdi tdm PVC bang phUdng phdp ISF hay trong thiic tl tao hinh cdc chi tilt diing tdm vdi nhdng hinh dang phdc tap khde nhau. Ddng thdi de xudt mot so gidi phdp han chi cdc dang hdng thudngxdy ra trong qud trinh tao hinh ISF tren tdm nhiia PVC.
ABSTRACT
Incremental Sheet Forming (ISF) is a potential technology that could be applied in rapid prototyping of sheet material. The article focuses on setting up the process of ISF on heated PVC sheet, using for experimental studies and in industry with different complex shapes planes. The article also suggests some measures to restrict the types of the damages, usually occurred during the forming of the PVC sheets by ISF.
Keyword: ISF process, forming of PVC sheets.
1. GlOfI THIEU _ l^m ngupi, ddpc tiln hdnh d trang thai chay hoac trang thdi deo vd chi thich hpp cho san Vdt lieu polymer chilm mdt ti 11 khd xuat hdng loat vi chi phi v l ndng ldpng va sii Idn trong ddi sdng hdng ngdy bdi trong thdc dau td trang thilt bi cao. Do vay, d l ddp ling t l cd rat nhilu sdn pham ddn dung vd cdng cdc yeu cau v l hieu qua kinh t l cho chi phi nghiep ddpc ldm td nhda. Cdc ky thudt truyin thap, phu hpp vdi sdn xuat dPn chile, 16 nho, thdng d l sdn xuat ra cdc sdn pham polymer tao mau nhanh thi can tim kilm cdc ky thu|t phan Idn dda vdo qui trinh gia nhiet - tao hinh sdn xuat mdi linh hoat hPn.
TAP CHf CO KHf VlfiT NAM • S6 1+2 (T^-«" i +^ "Sm 9017^
NGHIEN CUfU - TRAO DO I
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dddng chay dao phdi lap trinh tren mdy tinh, sau dd, kilm tra dddng chay md phdng, rdi xudt chdPng trinh sang mdy CNC.
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Hinh 1: Cdc thdnh phdn trong qui trinh tao hinh ISF dang SPIF
Vdi nhiem vu thay thi cdc phdPng phdp thong thddng trong viec tao ra cdc sdn pham nhda md van ddp dng cdc ylu cau ky thudt, mdt cdng nghe tao hinh tam mdi dd ddpc phdt triin trong nhdng nam qua gpi Id cdng nghe ISF (Incre- mental Sheet Forming). Hai dang cua cdng nghe ndy Id SPIF (Single point incremental forming) vd TPIF (Two point incremental forming). Luc ddu, cdng nghe ddpc nghiln cdu trin vdt lieu kim loai, ve sau ndy pham vi tim hiiu ddpc md rdng thIm tren cdc vdt lieu polymer, composite. Trong cdng nghe ISF thilt bi thddng Id mdt khung don gidn de kep tam vdt Uilu, trong khi sii tao hinh ddpc thdc hiln bang mdt dung cu dxiac di chuyin dpc theo dddng biln dang dd ddpc lap trinh san bdi mdy CNC hoac Robot cdng nghiep, hinh 1.
Trong qui truih ISF ddi vdi tam nhda nhiet deo hay cu thi Id tam nhda PVC, cd rat nhieu thdng so dnh hddng din khd ndng tao hinh cua chi tilt, mdt trong sd dd la thdng sd nhiet dp tao hinh T do tinh nhay vi nhiet cua nhda. Do dd viec nghiln cdu xdy ddng quy trinh gia cdng tao hinh tam nhda PVS bang phdPng phdp ISF Id can thilt.
2.C0SdLYTHUYET 2.1. Thiet ke va gia cong
Chi tilt ddpc thilt k l vd gia cdng md phdng bang phan mem CAD/CAM tich hpp chuyen dung nhd Pro/E, CATLV, Mastercam, Cimatron hoac cdc phan mIm thilt k l nhd Acad, Inventor, Solidwork... rdi chuyin sang phan mIm CAM dl gia cdng tao hinh.
Ddi vdi cdc chi tilt phdc tap vd cd nhilu
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Hinh 2: Cac dang bddc xuong dao cua dung cu Quy dao di chuyin cua dung cu ddpc lap trinh sdn theo hinh dang cua chi tilt. Bddc xudng dao cd 03 dang nhd sau: theo phdPng thang ddng td trin xudng, tao vdi mat phang nam ngang mdt gdc a, hoac cd dang hinh xoan dc [1], [2] (hinh 2).
2.2. May gia cong
Qui trinh cd the ddpc thiic hien trin may phay chuyin dung, mdy phay CNC trung tdm 03 true, 05 true, hoac robot cdng nghiep. So dd nguyin ly vd he thdng dilu khiln cua mdy tao hinh NC khdng khudn cd dang nhd hinh 3 [3].
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Hinh 3: So dd nguyen ly cua may tao hinh NC khdng khudn D l ddm bdo chat IdPng bl mat cung nhd dp chinh xdc tdt hPn, nIn tiln hdnh qui trinh tao hinh tren mdy phay CNC trung tdm vi khi dd he thdng cd sd cdng vdng hon khi tao hinh tren ro- bot mac du khi so sdnh thi robot vdpt trdi ve tinh linh boat.
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Hinh 4: Do gd trong qui trinh ISF 2.3. D6 gd
Dp chinh xdc cua do gd gdp phdn quan trpng din dp chinh xdc cua chi tilt [4]. Do vay nd phdi ddpc chi tao khd chuan, ddm bdo khi lap vdo thi phdi tam khdng bi cong venh. Tuy theo hinh dang chi tilt tao hinh md chi tao dd gd sao cho cd kich cd vd hinh ddng hpp ly
Ddi vdi vdt lieu khdo sdt Id nhda, do tinh nhay vdi nhiet dp nen can thilt phdi chi tao do gd cd gia nhiet de nghien cdu khd ndng biln dang d cdc trang thdi nhiet dp khde nhau.
cdch cdc dilm dung cu trdpt tren phdi tdm la nho hpn.
2.5. Dung dich bdi trPn
Trong qud trinh tao hinh can thilt, phaico sd bdi trPn tren bl mat tam nhda. Sd bdi trdn lam gidm ma sdt gida dung cu vd b l mat tdm va hap thu ldpng nhi|t gdy ra bdi sd biln dang nhii vet xodn cue bp. Ldu ldpng chdt bdi trPn phu thuoc vdo loai vdt li|u vd chieu ddy cua tam.
Hinh 5: Mdt so loai dung cu tao hinh trong qui trinh ISF 2.4. Dung cu
Dung cu gia cdng ddpc chi tao bang thep cdng de chdng mdi mdn vd biln dang trong qud trinh gia cdng. Cdc vdt lieu nIn sii dung ldm dung cu Id: thep gid, hpp kim Carbit, thep phu mdt ldp vdt lieu chdng ma sdt (nhd TiN, CrN, DLC), thep tdc dp cao... Dau dung cu dung d l gia cdng cd dang hinh bdn cau [5], [6] (hinh 5), vdi dddng kinh tdi thilu Id 6mm. Dddng kinh dung cu dnh hddng din chat ldpng b l mat cua chi tilt vd dddng kinh cdng Idn thi b l mat cdng nhan vi khoang
Hinh 6: Bdi trOn bang md trong qui trinh tao hinh ISF [3]
Dung dich bdi trPn cd thi Id md - hinh 6, nhdt (tuy theo vdt lieu vd b l ddy cua chi tilt ma chpn loai SAE ndo cho phu hpp), hoac dung dich trpn ngudi Emuxin.
Ndi chung, trong qui trinh tao hinh ISF, viec sii dung md bdi trPn, dung dich trPn nguoi se tuy thupc vdo tinh chat cua tdng loai vdt heu nhiia vd chilu ddy cua chung.
3. QUI TRiNH TAO HINH ISF TREN TAM NHl/A PVC
Gia cdng tao hinh ISF tren tam nhda nhiet deo cung gidng nhd khi thdc hien trin tam kim loai, dung cu di chuyin ldm biln dang deo tam nhda theo hinh dang dd ddpc md td. Phan tam khdng tao hinh ddpc kep chat bang khung kepd?t tren ban mdy Chi tilt gia cdng vd dddng di cia dung cu ddpc xdy ddng td md hinh CAD/CAM [7] (hinh 7). Cdc thdnh phan cP bdn ciia cong TAP CHf CO KHf VIET NAM
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S6 1+2 (Thang 1+2 nam 2012)NGHIEN CUfU - TRAO D(!)l
cua cdng nghe ISF (dang SPIF) ddpc t h i hien t r o n g h i n h S [8].
Dung cu -__^
de khdng cd bat ky mdt sai sdt ndo. Nlu mpi viec khdng cd van de gi thi sdn pham se tdng bddc ddpc tao hinh nhd dddng chay dao cua dung cu theo biln dang cua chi tilt cho d i n khi dddng chay cudi cung kit thuc.
ISF
Hinh 7: Mo hinh CAI^ v(Vi cac duoiig cha\' dao cua qui trinh tao hinh ISF
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Tao hinh ISF cho san pham
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Hinh 8: Cac thanh phan cd ban cua qui trinh tao hinh ISF
Trmh td thdc liien qui trinh co the tom tat nhd sau:
1/ Thilt klmd phdng chi tilt: Chi tilt ddpc thilt ke cd hinh ddng hinh hpc theo ylu cau cua ngddi s^ dung. Viec md phdng chi tilt Id nhd mdy tinh tren co sd sd dung cdc phan m l m thilt k l nhd:
Acad, Inventor, Solidvs^ork... Hay dung cic phdn mem tich hpp thilt k l vd gia cdng md phdng nhd:
Pro/E, CATIA, Mastercam, Cimatron...
2/lap trinh gia cdng chi tilt: cd hai cdch: 1) Lap trinh trdc tilp tren mdy phay CNC bang cdc chdong trinh vd cdc cdu lenh cd san t r i n mdy. 2) Hoac lap trinh rdi chay gia cdng thd tren mdy tinh r6i xuat sang mdy CNC. Cdch ndy an todn hon vi biet ddpc cdc sai sdt khi nhap cdc dd lieu khdng
^ling vd siia chda kip thdi md khdng gdy ra hd hong cho sdn pham vd Qidy gia cdng.
y Tiln hdnh gia cdng: Bddc nay ddi hdi ngddi
<iiing mdy phdi thuan thuc cdc thao tdc van hdnh
Hinh 9: So do torn tat cac bddc thdc hien trong qui trinh tao hinh ISF
4/ Hodn thdnh sdn phdm: Sdn pham ddpc coi Id hodn chinh khi hinh ddng hinh hpc cua nd dung vdi ylu cdu thilt kl. Vi vay, sau khi kit thuc qud trinh gia cdng phdi kilm tra lai kich thddc chi tilt.
N l u cd cdc sai lech Idn md khdng phdi Id sai sd gia cdng thi phdi kilm tra lai cdc dd lieu thilt ke vd chinh sda lai. Qui trinh gia cdng tao hinh tam biln dang cue bd liln tuc ISF trin vdt lieu tam nhda nhiet deo ddpc the hiln nhd trin hinh 9 [9].
Ngoai qui trinh ra can thdc hiln them mot sd thao tac khac:
Chon lUa vdt lieu tdm: Vdt lieu tam nhda PVC phdi dung ylu cau.
Kep chdt tdm nht^a trin do gd. Dd gd cung ddpc CO dinh tren bdn mdy Tat cd dIu ddpc h i n kit bang cdc bu Idng - dai dc.
Gd ddt dung cu vdo ddu gid dao vd xilt chat.
Chilu ddi ldm vile cua dung cu phdi hpp ly sao cho du tao ra chilu sdu cua chi tilt md khdng bi cong, cung nhd it rung ddng khi gia cdng.
Cdn chi tao them dUdng tao hinh n l u Id qui trinh tao hinh hai dilm (TPIF).
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Tim gdc gidi han biln dang Idn nhdt khi sU hU cP hpc vi dng sudt klo thing ddng. Hinh thai ck hdng cua chi tilt xudt hien sau mot Idn chay: Dung cdc khe ndt vd nhdng dddng lan truyin dpc theo cdc dung cu do khodng cdch, dung cp do gdc vd cd hddng chu vi Id tdPng td vdi sd hd hdng ddpc tim thi ddng them do gd. thdy trong qui trinh SPIF tren kim loai.
Tat ca cdc bddc trin phdi ddpc thdc hi|n can than trong qud trinh tao hinh. Neu cd sd gidn doan hoac sai sdt d cdc bddc tren thi phdi thpc hien lai mat rat nhilu thdi gian vd cdng sdc.
4. M O T SO HI/ H 6 N G X A Y R A TRONG QUA TRiNH GLV C O N G TAO HiNH ISF
4.1. Cdc dang xodn, rdch
Cdc hd hdng xuat hien trin chi tilt khi tao hinh ISF tren tdm PVC nhd hinh 10.
Hinh 10: Cac chi tiet bi hd hong sau khi tao hinh ISF tren tam nhda PVC
Dang hu hdng 1: Sxi hd hdng xuat hiln d vung chi tilt bi ldi nhd: vdt lieu khdng ddng chat, b l ddy tam khdng ddng dIu, bl mat phdi tdm bi tray xddc. Ddi vdi md hinh ndy, vit rdch md rpng do dng suat cua dung cu tdc ddng lln bl mat bi tray xddc khi tao hinh d nhiet dp phdng (300C).
Tuy nhiln, nlu vit xddc khdng qud Idn trong trddng hpp tao hinh cd gia nhiet thi khdng cd hiln tdpng rdch xdy ra.
Dang hu hdng 2: Vet rdch theo hddng chuyin ddng trdn cua dung cu d vung tilp gidp bdn kinh gdc gida thdnh nghieng vd mat ddy Dang hdng ndy xuat hien d chi dp: bddc xudng Idn, dddng kinh dung cu nhd, nhiet dp tao hinh cao. Sd biln dang ca hpc ddpc gdy ra bdi ldc cdng
Dang hu hdng 3: Sxi phdt triin cua cac vft xodn dpc theo thdnh nghieng cua chi tilt theo hddng chuyin d^ng quay cua true chinh do ma sdt khi di|n tich tilp xuc gida dung cu va tam nhda Idn.
Dang hu hdng 4: Cic vit ndt md rdng doc theo hddng phdn gidc trin thdnh nghiing chi tiet theo hddng ngdpc chilu di chuyin cua dung cu.
Theo dd, dda ra sd meo md sdm hon cua cac chi tilt vd cd lien quan din dng suat dd hinh thanh khi dung cu tao hinh tiln dpc theo hddng chu vi do CO sxi xudt hiln ddng thdi ciia sd trdpt tren bl mat vd ldc gdy ra sd udn theo hddng chu vi chuyin ddng.
4.2. Sd thay doi mau sac cua chi tiet
Nhiet dp cung ddng vai trd chinh trong hiln tdpng thay ddi mdu sac cua chi tilt sau khi tao hinh. Nhiet chu ylu sinh ra do ma sdt gifla dung cu bl mat tam PVC vd nhiet do tdm gia nhiet tao ra. Trong qud trinh tao hinh nlu tam nhda d nhilu trang thdi nhiet dp cao thap khac nhau thi chi tilt nhdn ddpc sau dd co chda cac dddng vdn sdng tdi khde nhau theo tdng ldp sau mdi bddc xudng dao (hinh 11).
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Hinh 11: Cac van sang toi dan xen nhau vi sU thay ddi nhiet dd
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Sd 1+2 -^Thiinff 1+2 nam 2012)NGHIEN c a u TRAO 061
Do vay d l khdng cd hien tdPng cdc van sdng tdi dan xen Idn nhau, dieu quan trong nhat la phdi gid cho nhiet dp ludn dn dinh trong sudt qud trinh tao hinh. Nhiem vu ndy ddng nghia vdi viec bat budc phdi dung dung dich tron ldm ngudi hoac cdc hdn hpp ldm mdt - bdi trPn nhd: nhdt- md, emuxin-md vd nhd vay se khdng cd hiln tdpng thay doi mdu sac chi tilt.
4.3. Vit cua dung cu
Sau mdi mdt vdng tiln dao thi dung cu se di chuyin xudng mdt bddc Az gpi id bddc xudng dao tao nen vit nhd thang ddng trin chi tilt. Tap hpp tat cd cdc vit cua mdi bddc xudng Id mdt vet dai theo dddng sinh ddpc xem nhd Id vet cua dung cu (hinh 12), vit cdng rd khi gdc tao hinh cang Idn.
4.4. Hiln tdpng cong vInh
Hien tdpng chi tilt bi cong venh d phan khdng tao hinh rat de nhdn thay (hinh 13). Sd thay ddi nhiet dp Id nguyen nhdn chu yeu gdy nen tinh trang nay Dung cu tilp xuc vdi chi tilt sinh nhiet do ma sdt hoac nhiet sinh ra do do gd gia nhiet khi tao hinh d chi dp lam ndng. Ngodi ra, do gd chda hodn hdo cung gdy ra hiln tdpng cong vInh chi tilt. Do dd, sau khi chi tilt ddpc tao hinh xong, khdng nIn lay chi tilt ra ngay md can dl vdi phut cho din khi nhiet d vung tao hinh bang vdi nhiet d vung khdng tao hinh rdi mdi thao tam kep lay chi tilt ra.
Hinh 12: Vet cua bddc xudng dao tren dddng sinh cua chi tilt
Mdt gidi phdp khdng d l lai vit dung cu la lap quy dao cho dung cu di chuyin theo hinh xoan 6c vdi mdt dilm bat dau vd mdt diem kit thuc. Bang cdch ndy thi loai bd ddpc vit nhdng lai xuat hien mdt vdi hiln tdpng bat Ipi khde do tinh chat ndi suy biln dang cua chdPng trinh CAM gay ra sd rung ddng trong qud trinh tao hinh, dp nhan thdp, ddi hdi mdy cd cdng suat mdy Idn.
Ngodi ra, khi tao hinh vdi bddc xudng dao lofn, trin chi tilt hiln rd cdc dddng chay dao cua dvng cu, vd dieu ndy ldm gidm ddng k l chat ldpng be mat. Do vay de tang chat ldpng b l mat cua sdn pham thi can thdc hien qud trinh tao hinh vdi biidc xudng dao nhd hon.
Hinh 13: Chi tiet cone thang bi venh sau khi tao hinh ISF
5. KET LUAN
Vdi cdc cdng vile dd thdc hiln, bdi bdo da gidi quylt ddpc nhdng van de:
Thiet lap qui trinh gia cdng tao hinh tam biln dang cue bd lien tuc ISF trin tam vat lieu PVC cd gia nhiet cd thi dng dung trong cdc nghiln cdu thdc nghiem tao hinh ddi vdi tam PVC bang phdPng phdp ISF hay trong thdc t l tao hinh cdc chi tilt dang tam vdi nhdng hinh dang phdc tap khde nhau.
- Due k l kinh nghiem, dl xuat mdt sd gidi phdp han chi cdc dang hdng thddng xdy ra trong qud trinh tao hinh ISF tren tam nhda PVC. • TAP CHf CO KHf VIET NAM
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Tai lieu tham khao:
[1]. Nguyen Thanh Nam. Bdo cdo nghi|m thu de tdi: Nghien cdu cdng nghe tao hinh nhdm tdm khong dung khudn. Trddng Dai hpc Bdch khoa, Dai hpc Qudc gia TR Hd Chi Minh, 2008.
[2]. V. Oleksikl, O. Bologal, R. Breazl, G. Racz ' Comparison between the numerical simulations of incremental sheet forming and conventional stretch forming process 1 "Lucian Blaga" University of Sibiu, Engineering Faculty 4 Emil Cioran Street, 550025, Sibiu, Romania.
[3]. Lotta Lamminen, Boel Wadman, Rein Kiittner, Torgeir Svinning - Prototyping and low volume production of sheet metal components - Helsinki University of Technology, Finland.
[4]. G. Ambrogio, L. Filice, F. Gagliardi and F. Micari Three-Dimensional FE Simulation of Single Point Incremental Forming: Experimental Evidences and Process Design Improving Department of Mechanical Engineering, University of Calabria, Arcavacata of Rende, 87036 Cosenza, Italy.
[5]. J. JeswietS F. Micari^ G. Hirt^ A. Bramle/, J. Duflou^ J. Allwood^ Asymmetric Single Point Incremental Forming of Sheet Metal - 'Queen's University, Kingston, ON, Canada; -University of Paler- mo, Palermo, Italy; ^University of Aachen, Germany; ^University of Bath, United Kingdom; 'Katholieke Universiteit Leuven, Belgium; ^University of Cambridge, Cambridge, England.
[6]. Rui Manuel dos Santos Oliveira Baptista, Paulo Antonio Firme Martins, Maria Beatriz Cipri- ano de Jesus Silva, Luis Manuel Mendon^a Alves - Single Point Incremental Forming - Universidade Tecnica de Lisboa, 9/2008.
[7]. W.C. Emmens *•*• G. Sebastiani ^ A.H. van den Boogaard ' The technology of Incremental Sheet Forming-A brief review of the history a CORUS RD&T, PC Box 10.000, 1970 CA IJmuiden, The Netherlands; b Institute of Forming Technology and Lightweight Construction (lUL), Technische Universitat Dortmund, Baroper Strasse 301, 44227 Dortmund, Germany; c University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands, 02/2010.
[8]. V. S. Lei*, T. N. NguyenS K. D. Le\ A. Ghiottil, G. ucchettal - Incremental sheet forming of glass mat thermoplastic 'DIMEG - University of Padova Via Venezia, 1, 35131 Padova, Italy; ^De- partment of Machine Design - HoChiMinh City University of Technology, Viet Nam.
[9]. Jukka Tuomi, and Lotta Lamminen Incremental Sheet Forming as a Method for Sheet Metal Component Prototyping and Manufacturing BIT Research Centre, Helsinki University of Technol- ogy PoBox 5500, FIN-02015 HUT, Finland.
^ TAP CHf CO KHf VIET NAM • Sd 1+2 (T^^-"" I +^ n3m 9012^