Đánh giá quá trình gia nhiệt cho lòng khuôn hình chữ nhật bằng phương pháp phun khí nóng từ bên ngoài

Tgp Chi Khoa Hfc Gido Due Ky Thuat (33/2015) Tnrcmg Bai Hpc SirPhfm Ky Thufl TP Hd Chi Minh DANH GIA QUA TRINH GIA NHIET CHO LONG KHUON HINH C H C NHALT B A N G PHU'ONG PHAP PHUN KHI NONG TU' BEN NGOAI EVALUATION OF HEATING PROCESS FOR THE RESTANGULAR I40LD CAVITY BY EXTERNAL GAS-ASSISTED HEATING Ph?m Son Minh', Do Thanh Trung', Nguyin Hp', Phan The NhSn' 'Tnrdng Bgi Hoc SuPhgm Ky Thugt TR HCM ^Truang Dgi Hoc Cong Nghe Dong Nai 'Truang Cao Ding Nghi Ky Thugt Cong Nghf TRHCM Ngay toa so^n nhin bit 23/3/2015, ngiy phan bien gia 6/4/2015, ngiy ctiap nhin dang 10/4/2 TOM TAT Nhdm ndng cao nhiet be mat long khuon hmh chu: nhat tnrac nhua nong chay dirge ep vdo khudn phun ep, phuangphdp gia nhiet cho bi mat khudn bdng nong da dirge img dirng Trong nghien cicu nay, nguon nong 200 °C da dugc sir dung cho qud trinh gia nhiet be mat khuon v&i be mat gia nhiet hinh chir nhat co kich thuac 175 mm x 12 mm Thong qua qud trinh mo phong vaiphdn mem ANSYS, phuangphdp ndy cho thdy phdn bo nhiet tren be mat khuon khd tot Ben cgnh do, phuang phdp mo phong ciing cho thdy khd ndng dir dodn khd chinh xdc gid tri nhiet dii tgi be mat khuon Ngodi ra, phuang phdp thirc nghiem ciing da dugc sir dung de khdo sdt nhiet ctia be mat khuon theo thdi gian gia nhiet Kit qud thi nghiim cho thdy nhiet be mat khuon se tdng nhanh 10 s ddu cua qud trinh gia nhiet, sau do, 20 s tiep theo, gid tri ndy se tdng chgm vd on dinh sau 30 s Tgi th&i diem on dinh, nhiet tgi cdc diem khdo sdt dao dong khodng 83.5°C tiin 95''C Til- khda: Phun ep, khuon, gia nhiet bdng nong ABSTRACT For enhancing surface temperature of the rectangular mold cavity before injecting melt plastic into the mold, a gas assisted mold heating method (GAMH) was applied In this research, a 200oC airflow source was used for heating the rectangular mold cavity with the heating area size ofl 75mm x 12mm Based on the simulated results with ANSYS CFX, it was clear that the GAMH had a good temperature distribution on the ccn>ity surface of mold Also, the simulated method showed the ability to predict quite accurately the temperature value on the cavity surface of mold In addition, experiments were conducted to examine the temperature on the surface temperature as a function of heating time The experimental results showed that the mold surface temperature increased rapidly in thefirst10s, slowly in the next 20s, and became stable after thai At the stable state, the temperature values of several considered points of the mold variedfrom 83.5°Cto 95''C Keywords: Injection molding, mold, gas assisted mold heating GIOI THIEU Phun ep la cdng nghS phun nhua nong chay dugc dinh lugng chinh xac vao long mOt khuon dong kin vdi ap Ivrc cao va tdc d6 nhanh, sau thai gian ngin, san phim dugc dinh hinh, va dat dSn nhiet d6 nguoi theo ygy ^^y^ g^jj phSm dugc lay ngoai Sau do, chu ky phun ep tiSp theo se dugc ti8n hanh Thai gian tii liic dong khuSn, phun nhua, dinh hmh san phim, l4y san phSm khoi khuon, dong khuon ggi la chu ky ciia mgt lin ep san phim Trong qua trinh di6n nhua vao khuon Tap Chi Khoa Hfc Gido Di/c Ky Thuft (33/2015) Truing Bai Hoc Sir Pham Ky Thuat TR Ho ChiMinh voi san phim mong, nhung lop nhua tiSp xHc vai cua khuon (bS mat khu5n nhiet dg thip) se dong lai Qua trinh d5ng lai b6 mat tiSp xiic voi khuon se lam giam ap Ivc cua dong nhua lam cho nhua se khong dien diy dugc 16ng khuon [1,2] Hien nay, san phim nhua rit da djng, tit hinh dang don gian dSn phiic tap, tu kich thuac 16n dfe kich thuoc nho Vcri su phat tri8n ciia xS hgi, yeu ciu moi voi cong nghe phun 6p luon dugc dugc dat ra, mgt nhihig yeu ciu cip thiet nhat la ch§ tao cac san phim nhua bSng cong nghe phun ep voi bi day nho hon mm phuc vu cho cac chip sinh hgc, cac thijt bi quang hoc, Tu cac yen ciu nay, nhim khic phuc hien tugng d6ng dac qua nhanh cua dong nhvra chay long khuon, phuong phap nSng cao nhiet b6 mat long khuon da dugc de xuat [3, 4] Trong nghien cuu cua Chen et.al, nhiet tim khuon dugc nang tir 60 °C dfa 100 "C, sau d6 qua trinh diin diy nhua n6ng chay vao long khuon dugc tiSn hanh [2, 4] Trcng bai bao nay, cac mftc nhiet khac da dugc trinh bay K6t qua cho thiy thcri gian di nang nhiet dO khuon tir 60 °C dto 100 °C voi luu chit gia nhiet la nude, sg keo dai 53 s Vdi phuong phap nay, thdi gian chu ky se keo dai, dd, hieu qua kinh te se giam r5 ret De nit ngin thdi gian gia nhiet cho khuon, cac phuang phdp gia nhiet be mat khudn da dugc nghien cuu [5 - 8] Trong dd, phucmg phap dimg ndng de nang nhiet dO long khuon dang dugc nhigu nha nghien ciiu tap trung khai thac [7 - 8] Mgt nhimg khd khan cua phuang phdp la khd nSng dieu khi§n dong ndng nham giam chenh lech nhiet dd tai bi mat long khuon Do dd, nghien ciiu sB tap trung ling dung cdng cy CAE (Computer assited Engineering) nhim phan tich va dv doan kit qud gia nhiet bing ndng cho mpt bd khuon thvc ti vdi long khuon hinh chil nhat Thdng qua md phdng tren phin mim ANSYS CFX, cdc gid tri nhiet va su phdn bd nhiet dg tai bi mat long khuon sS dugc xac dinh Sau dd, thi nghiSm gia nhiSt se dugc tiin hanh nhim khao sdt nhiet cua be mat khudn theo thdi gian gia nhiet, cung nhu ddnh gia chmh xac ciia kit qud md phong M PHONG VA THi NGHIfM Trong nghien cuu nay, khudn phun ep dimg cho qud trinh thi nghiem vi ddng chay nhua dugc sii dung cho qud trinh nghien cuu kha nang gia nhi6t cho long khudn bdng ndng Kit ciu ldng khuon cin gia nhiet dugc trinh bay nhu Hinh Tim khuon dung cho qua trinh thi nghiem se dugc gia cdng vdi mgt ldng khuon vd mdt cdng vao nhua Tai bi m^t can gia nhi6t, ldng khudn dugc each nhiet bdi vat lieu nhua chiu nhiet va cd kich thudc nhu Hinh MBiii^raBltmiBl X ^•-m Hinh 1: Kit cdu long khudn r-w^m I—wwtr\ ^ W////////^AW////////////////////////////////////AW/\^ •w^ Kenh d i n nhya | Jil 'W//M -I s==znzz^ T^^g -ig-Tf "^ T =&Hinh 2; Kich thuac bg phdn cdch nhiet cho long khuon Tgp Chi Khoa Hgc Gido Due Ky Thugt (33/2015) I Tnr&ng Dgi Hgc Sir Phgm Ky Thugt TP Hd ChiMinh \ Trong qui trinh phun ep truyin thing, sau mgt chu ky phun ep dugc hoan thanh, hai tam khuon se md va sdn phdm se dugc day khdi long khuon Sau dd, hai tam khudn se ddng lai va mdt chu ky phun ep mdi se dugc bit ddu Tuy nhien, vdi qui trinh phun ep nhva vdi su hd trg cua ndng qud trinh gia nhi$t cho long khuon, sau san pham dugc day khdi ldng khudn, ca cdu tay may se dua ngudn nhiet vao giiia hai tdm khudn, sau dd, ndng tii ngudn nhiet se dugc phun tri^c tiep len vi tri can gia nhiet eho long khudn Vi tri ciia khudn va ngudn nhiet ndng dugc trinh bay nhu Hinh Sau nhiet dp ciia long khudn dat dugc gia tri theo yeu cdu, ngudn nhift se dugc di chuyen ngoai khu vuc khudn, sau do, hai tdm khudn ddng lai va chu ky phun ep mdi dugc bat dau :§ J i{ I LoDgkh a cin gia iihi;l Hinh 3: Vi tri cua khuon qud trinh gia nhit VilrivaQ 28 38 38 38 nhiia Trong linh vuc phun ep nhua, phdn bd nhiet dp t^i bi mat khudn cd y nghia rat quan trgng, ddy la mgt nhiing yeu td chinh cd Hinh 4: Vi tri nhiet tai be mat long khuon dnh hudng den cong venh sdn phdm nhua sau phun ep [1, 5] Do dd, cdc thi nghiem cua nghien ciiu nay, gia tri nhiet dp tai bi mat long khudn se dugc ghi nhdn vdi diim nhu Hinh Ngoai ra, nham quan sat phan bi nhiet tai be mat nay, phuang phap md phdng ciing se dupe thuc hi8n vdi phan mim ANSYS Md hinh md phdng dugc trinh bay nhu Hinh Cdc thdng so md phdng dugc cai dat nhu thi nghiem thuc nhu Bang Nhdm quan sat qua trinh gia nhiet cho ldng khudn phun ep nhua, ddng ndng vdi nhi^t dg 200 "C dugc phun len be mat long khudn thong qua cdng phun (Hinh 3) Thdi gian gia nhiet se dugc ghi nhan tu luc bat dau phun din 30 s Gia tri nhiet tai diem tren bi mat long khudn se dugc ghi nh$n tir thi nghi6m, sau do, cac kit qua thi nghiem se dugc so sanh Hinh 5: Mo hinh mo phong qud trinh gia nhi$t vdi kit qua md phdng bdng nong Tgp Chi Khoa Hoc Giao Due Ky Thuat (33/2015) Tnrdng Bfi Hoc Sir Pham Ky Thuat TR Ho ChiMinh Bing 1: Thong sd md phdng Thdng s6 mo phong Nhiet dp inlet cua khdng 30 °C Nhiet phun vdo khu vuc can gia nhiet 200 "C Khdi lugng rieng cua 1.185 kg/m^ Nhiet dung rieng ciia 1004 J/kg.K He sd gian nd vi nhiet ciia 0.003356 K ' Ap suat khdng atm Nhiet dp ban dau cua tam nhdm 30 "C Khdi lugng rieng cua nhdm 2702 kg/m^ Nhiet dung rieng cua nhdm 903 J/kg.K H6 sd din nhiet ciia nhdm 237 W/m.K He sd truyen nhiet tir khdi sang tam nhdm 2340 W/m.K D^ng phan tich nhiet Transient Cac miic thdi gian phdn tich Osa30s (budc s) Budc tdi thieu cho mdt miic thdi gian phan tich Is Thdi gian khdi tao ban dau Os KET QUA VA THAO LUAN Ket qua md phdng va thi nghiem tai cdc vi tri khac tren be mat long khudn vdi thdi gian gia nhiet 30 s dugc trinh bay nhu Bang Trong qua trinh thi nghiem, su thay ddi nhiet dp tai diem dugc trinh bay nhu Hinh Ket qua thi nghiem cho thdy 10 s ddu, nhiet dp tai diem (Hmh 4) tang rdt nhanh Tuy nhien, su tang nhiet dp chdm lai 20 s tiip theo Sau dd, tu giay thii 30 trd di, nhiet dp tai diim se dat din gia tri dn dinh Vdi vi tri do, nhiet dp i n dinh dao dgng khoang 83.5 "C din 95 °C Vdi ket qud nay, phuang phap md phdng se dugc thuc hien vdi thdi gian gia nhiSt 30 s nhim quan sat phan bd nhiet tai be mat khudn Kit qua so sdnh giiia md phdng va thi nghiem v i phan bd nhiet dg tai diim thdi gian gia nhiet 30 s dugc trinh bay Hinh (diim PI), Hinh (diim P2), Hmh (diim P3) va Hinh 10 (diim P4) Cdc kit qud cho thdy 10 s ddu tien cua qud trinh gia nhiet, sai lech gifta kit qua md phdng va thuc nghiem dudi "C Tuy nhien, tir 10 s din 30 s, su khdc biet v i nhiet gifta md phdng va thuc nghiem thay ddi theo chiiu hudng tang (sai lech Idn nhdt khodng 10 "C) Hien tugng cho thdy qua trinh md phdng da bi anh hudng bdi dac tinh vat lieu va cdc di8u kien bien cua qua trinh gia nhiet Ngodi ra, gidi han cua trang thiet bi md phdng, kich thudc ludi va phdn hi chua dugc tdi uu hoa Tuy nhien, nhm chung cac ket qua tft Hinh din Hinh 10 cho thdy su tuang ddi giing giua md phdng va thuc nghiem tai tat cd cac vi tri khao sdt Vi vay, cd the du doan qud trinh gia nhiet bang ndng bang phdn m6m m6 phdng ANSYS CFX Phdn bd nhiet tai b6 mat long khudn iing vdi cdc thdi gian gia nhiet khac ciing dugc so sdnh nhu Hinh 11 Ket qua cho thay 10 s dau cua qua trinh gia nhiet, qua trinh truyen nhiet gifta ndng va long khudn dien rat manh chenh lech nhiet dp gifta ldng khudn va rat Idn, ket qua la nhiet dp cua ldng khudn gdn cdng phun se tang nhanh Tuy nhien, nhiet dp long khudn tang cao, qud trinh truyen nhiet ddi luu gifta vd long khudn se giam ddng ke, ben canh do, nhiet nang tai cac vi tri se truyen nhung vi tri cd nhiet dp thdp hon Do dd, tit 10 s den 30 s, su mdt can bdng nhiet dp da giam ddng ke Ngodi ra, Hinh 11 cho thay phan bd nhiet tai thdi diem 30 s vdi chenh lech nhiet cua cd b i mat long khudn la 11.5 "C Vdi chenh lech nhiet dp nay, phuong phdp gia nhiet bdng ndng tu ben ngodi hoan toan co the ling dung cho qui trinh phun ep Tgp Chi Khoa Hgc Gido D^c Ky Thugt (33/2015) Tnr&ng Dgi Hgc Sir Phgm Ky Thugt TP Hd ChiMinh Bdng 2: Kit qud nhiet dg tgi be mat khuon tgi mot so vi tri khdc ThM gian Vitri Kit qua Kit qua gia nhift mfi phong thi nghiem 62 59 58 57 5s 56 58 57 55 76 74 78 75 10 74 73 74 75 90 81 87 80 15 86 83 85 82 92 86 90 87 20 88 82 84 85 95 87 92 83 25 86 91 84 86 86 95 94 83.5 30 84 94 84 86 I Pi 200*C Ttin^iSni Pl_200°C_M6plmg Thoi gian gia nhi?l(s) Hinh 7: Bo thi so sdnh nhiet tgi diem PI v&i th&i gian gia nhiet 30 s n 200°C TliinEhiem P2_2{IO'X:_M6ph6i^ Then gian gia nhiet (s) Hinh 8: Do thi so sdnh nhiet tgi diem P2 v&i th&i gian gia nhiet 30 s —B-PS 200 °C ThinEhiem Thfii gisn gia ntai^t (s) Hinh 6: Thi nghiem su thay doi cua nhiet tgi diem tren be mat long khuon qud trinh gia nhi^t Thdi gian gia nhi^t (s) Hinh 9: Do thi so sdnh nhiet tgi diem P3 v&i th&i gian gia nhiet 30 s Tfp Chi Khoa Hoc Giao Due Ky Thuat (33/2015) Tmdng Bai Hoc SirPhfm Ky Thuat TR Hd ChiMinh KET LUAN Qud trinh gia nhiet cho long khudn hinh chft nhat bdng phuong phap phun ndng tft ben ngoai dugc nghien ciiu thdng qua md phdng va thi nghiem vdi mdt sd kdt luan nhu sau: Thdi gian gia nhi?( (s) Hinh 10: Do thi so sdnh nhiet tgi diem P4 v&i th&i gian gia nhiet 30 s Kit qua thi nghiem cho thdy gia nhiet bdng ndng tu ben ngoai, nhiet bi mat khudn se tdng nhanh 10 s dau, sau do, gid tri se tang cham 20 s tiip theo va dn dinh sau 30 s Tai thdi diem dn dinh, nhiet dugc phdn bd tuong doi ddng diu (ch6nh lech khoang 11.5 °C) Vi vdy, phuong phdp gia nhiet bdng ndng tu ben ngoai hoan toan cd the iing dung cho qui trinh phun ep nhua Kit qud so sanh gifta md phdng va thi nghiem cho thdy sy sai lech khdng Idn tai tdt cd cac vi tri khao sat tren be mat khudn Vi vay, cd the sir dung phan mem md phdng ANSYS CFX d i du dodn nhiet phan bi tren be mat long khudn qua trinh gia nhiet bang ndng, qua cd the ddnh gia chat lugng chat lugng sdn phdm Hinh 11: Phdn bo nhiet tgi ldng khuon img v&i cdc th&i gian gia nhiet khdc TAI LIEU THAM KHAO [1] S Y Yang, S.-C Nian, S.-T Huang and Y.-J Weng, A study on the micro-injection molding of multi-cavity ultra-thin parts Polymers Advances Technologies, Vol 22, 2011, pp 891-902 [2] Y K Shen, C F Huang, Y S Shen, S C Hsu, M W Wu, Analysis for microstructure of micro lens arrays on micro-injection molding by numerical simulation, Intemational Communications in Heat and Mass Transfer, Vol 35, 2008, pp 1097-1100 [3] K F Zhang, Z Lu, Analysis of morphology and performance ofPP microstructures manufactured hy micro injection molding, Microsyst Technol, Vol 14, 2008, pp 209-214 [4] B Sha, S Dimov, C Griffiths, M.S Packianather,/«ve5//ga//o« ofmicro-injection moulding: Factors affecting the replication quality Journal of Materials Processing Technology, Vol 183, 2007, pp 284-296 [5] S C Chen, D Chien, S H Lin, M C Lin, J A Chang, Feasibility evaluation of gasassisted heating for mold surface temperature control during injection molding process, Intemational Communications in Heat and Mass Transfer, Vo' '^^ "'^^^ " " Sfi(^-sn Tfp Chi Khoa Hfc Giao Dfic Ky Thuat (33/2015) Truang Bfi Hpc Sir Pham Ky Thuat TR Hd Chi Mmh [6] S C Chen,W R Jong, J A Chang, H S Peng, Simulation and verification on rapid mold surface heating/cooling using electromagnetic induction technology, 4th Intemational Conference on Heat Transfer, Fluid Mechanics and Thermodynamics Cairo, Egypt, 2005 [7] S C Chen, Y W Lin, R D Chien, H.M Li, Variable Mold Temperature to Improve Surface Quality of Microcellular Injection Molded Parts Using Induction Heating Technology, Advances in Polymer Technology, Vol 27, 2008, pp 224-232 [8] S C Chen, J A Chang, Y C Wang, C F Yeh, Development of Gas-Assisted Dynamic Mold Temperature Control System and Its Applicationfor Micro Molding, ANTEC, 2008, pp 2208-2212  ... trinh gia nhiet cho ldng khudn phun ep nhua, ddng ndng vdi nhi^t dg 200 "C dugc phun len be mat long khudn thong qua cdng phun (Hinh 3) Thdi gian gia nhiet se dugc ghi nhan tu luc bat dau phun. .. Ttin^iSni Pl_200°C_M6plmg Thoi gian gia nhi?l(s) Hinh 7: Bo thi so sdnh nhiet tgi diem PI v&i th&i gian gia nhiet 30 s n 200°C TliinEhiem P2_2{IO''X:_M6ph6i^ Then gian gia nhiet (s) Hinh 8: Do thi... v&i th&i gian gia nhiet 30 s —B-PS 200 °C ThinEhiem Thfii gisn gia ntai^t (s) Hinh 6: Thi nghiem su thay doi cua nhiet tgi diem tren be mat long khuon qud trinh gia nhi^t Thdi gian gia nhi^t