NGHIEN cuu-TRAODOI NGHIEN CUu ANH HUONG CUA CAC THONG SO KY THUAT DEN CHAT LUONG DUO CHI TIET N H U A KY THUAT STUDY ON THE EFFECT OF TECHNICAL PARAMETERS ON MOLDING QUALITY OF TECHNICAL PLASTIC PARTS TS Truong H6ng Minh', KS Luu Van Quy', ThS Nguyin Cong Hieu» 'Cong ty TNHH Thuong mai va Dich vu Cong nghiep Nhat Minh ^Truong Dai hoc Bach Khoa Ha Noi TOM TAT Bdi bda ndy trinh bdy nghien cim dnh hudng cua cdc thang sd ky thugt diicphun gim nhiet dd cdc vimg xy lanh, nhiet dp khiidn, dp luc phun, dp luc ddy, luc luc kep khuon, thdi gian phun, gian hni dp thai gian Idm nguoi, tdc dp phun, tdc dp quay ciia due vll, tdc dp ddng md khuon din c luang ciia chi tiet nhua ky thugt Tir dua cdc khuyin cdo cho cdc nhd chi tgo cdc linh kien nh ky thugt Bdy Id cdc kit qud duac diic kit tii qud trinh nghien cuu vd chi tgo cdc chi tiit nhua cd chinh xdc cao Igi Cdng ty Nhdt Minh Til khoa: Nhiet dp phun, dp luc phun, thai gian phun, tdc dp phun ABSTRACT This paper shidies the effect of technical parameters of injection molding including the tempera ofthe regions in cylinder, molding temperature, infection pressure, molding clamp force, injection pressure holding time, cooling time, injection velocity, rotatipn velocity of screw, closing and op veloci^ on quality of technical plastic parts From thatpoini this paper gives the recommendations fo •"'' f^'-r^rsoftechnical plastic parts These results obtainedfrom the study and the fabricationof plastic part with high precision at the Nhat Minh company Keyword,: Injection temperature, injection pressure, injection time, injection velpcity TAP CHi CO KHi VIET NAM, S6 1+2 nam 2014 www.cokhivietnam.vn NGHIEN cuu-TRAODOI 1, DAT VAN BE Dieu kien diic la cac thdng sd thiSt lap d^ hue bi^n mdt qua trinh ep phun san pham nhua :u nap va gia nhiet lam ndng chay nguyen lieu, ihun phu vao khudn, luu ap, lam ngudi va liy jan phim ngoai Ngoai khudn diic thi di^u d$n diic phun la yeu td quan trpng anh hudng di chat lupng san pham Di6u kien phun phu inh hudng tdi ngog.i quan, dieu kien luu ap anh ludng tdi kich thudc va dp cong venh cua san jham Ngoai ra, dieu kien diic phun anh hudng tdi lang suat san xuat - chu ky due, khdng the thiet ap dieu kien diic vdi chu ky qua dai Can thiet Dm gia nhiit phai thiet lap dieu kien diic de vira dam bao chat lupng san pham, vira phai dam bao hieu qua san xuat, tudi tho khudn ANH HlTOTVG CUA CAC THONG SO DEN CHAT LlTONG CHI TIET DUC a) Nhiet sy lanh va nhiet khudn Cdng nghe due phun nhua la qua trinh phun nhua ndng chay vao khudn, vi vay nhua phai dupc gia nhiet den nhiet dd ndng chay Ngudn tao va cung cap nhiet d may due phun hien la cac dai gia nhiet diing dien trd (Band Heaters) bd tri xung quanh xylanh cua may diic phun (hinh 1) Xy-lanh Pheu cap b^u Hinh 1: He thong Idm nong chdy hgt nhua nguyen lieu Nhua tir phlu chay vao xy lanh va chai qua giai doan nap - nen - ndng chay, vi vay nhiet xy inh nen duac thi^t lap tir thap den ndng chay Nhiet dp mdi viing each khoang S-IS^C cho dat bua luu d phia trude diu true vit dat din nhiet ndng chay mong mudn ^ TAP CHi CO KHi VIET NAM So 1+2 nam 2014 www.cokhivietnam.vn IGHIENCIJU-TRAO DOI Dai nhiet dp nong chdy ciia nhua khd rpng, dp vdi sdn phdm cd chiiu ddy mdng nen due miin nhiet dp cao di tdng dp chdy hdng di phun nhanh vda khudn 'Can - (25%L) -^ Nap \eu Nhiet ap nong chay, Tnc \ r ~(5-io) c > 1 Tnt -(5-lS) 50°C ~ 80°C A • Hinh 2: Cach thiet lap nhiet dp xy lanh Nhiet ldiu6n hi anh huong Ion bdi chu trinh diic, co ngot, tinh chit va hinh dang san pham, Nhiet ldiu6n du(?c Idem soat thong qua bo phan dieu tiet nhiet Ichuon (nuoc, dau,.,,), nhung Idia voi \dhm soat nhiet xylanh gia nhiet, khong phai cho toan bp va cho timg chuc nang, va no anh huotii rit Ion den nang suit san xuat, chat lugng san pham diic Bang Nhiet dp xy lanh vd nhiet dp khudn ciia mot sd logi nhua [I] Nhiet dp xylanh (°C) Nhi$t dp khuon ("C^, Poly etyrene Nhya - -300 34 + 65 Poly propyrene 180- -300 20^80 Thong thuong 150- -300 40 + 70 Kho chay 180- -210 40 + 70 Nhua AS 170- -290 40 + 80 NhuaABS 180- -250 50 + 70 Nhua methacrylic 180 - 260 59-95 Poly styrene Poly chloride Vinyl 150- - 50 + 70 Poly amide (66) 0 60 + 120 Poly acetal Poly carbonate 175 - 60 + 100 Thong thuong 270 - 0 70 + 120 Co thiiy tinh 280 - 40 + 100 I TAP CHi CO KHi VIET NAM, S6 1+2 nam 2014 www.cokhivietnam.vn NGHIEN CIJU-TRAO DOI ^-^- Nhua PPE cd tinh thay ddi Nhiet dp xylanh (»C) Nhiet dp khuon (°C) Thdng thudng 240 + 260 40 + 60 Cd thuy tinh 280 + 310 40 + 100 PBT 230 + 270 50 + 120 PPS 310 + 340 120+150 PES 340 - 380 110+150 b) Ap luc phun, dp luc ddy vd luc luc kep khudn * Ap luc phun VP - S0 < (-1 > 1 < A p Ivc p h u n giiM h^n Ap luc [^ Nhu vay, de phun dupc nhua ndng chay ve cudi san pham thi ap luc phun phai Idn ban tdng trd luc (mat ap luc) tren dudng di cua nhua Tuy nhien, ap luc phun cdn phu thudc vao van tdc phun - thdng sd duoc uu tien d giai doan phun de dam bao chat luang be mat san pham, dd may due chi quan ly ap luc phun Idn nhat Hinh 3: Ap luc thuc te ciia nhua tiong qud trinh phun Hinh 4: Quan he giiia van tdc phun vd dp lire phun Ap luc phun la trd luc nhua ndng chay xy-lanh bi nen ngan can true vit tien len qua trinh phun nhua, kgf/cm^ Ap luc khdng phai la ap luc cua nhua pbin tao hinh san phim khudn, ma di qua ranh rdt, ranh din nhua, cdng khudn, nen thuc t8 qua trinh da mit di luang ap luc rat Idn Miic mat ap luc cirng khac hiy thudc vao chiing loai nguyen lieu due, nhiet dp xylanh, nhiet dd khudn, toe dp phun, hoac hinh d^g ciia ranh rdt, ranh din nhua cdng khudn, va khdng di^ tinh duoc dan gian Trudng hop la may due phun ki6u hue vit cd the bi xudng 50% Ddi vdi nhung loai nhua luu ddng chay kem nhu nhua methacrylic, poly carbonate, nhua vinyl chloride cirng, mat ap luc Idn, doi vdi nhirng nhua cd tinh luu ddng cao nhu poly etyrene, poly amide, mat ap luc it Gidi han ap luc phun Idn nhat la ap luc gidi ban cho phep Idn nhat toan qua trinh phun Neu ap luc phun thuc te dat den gia tri thi may due se tu dieu chinh giam van tdc phun de ap luc phun khdng vuat qua gia tri cai dat Do vay, neu gidi ban ap luc phun Idn nhat duoc thiet lap thap ban tdng tdn thit ap lye thi se khdng the phun duoc nhua ve cudi san pham nhu phan tich tren, dd san pham se bi thieu nhua, Tiic la chiing ta phai thiet lap ap luc phun Idn nhat Idn hon ap luc thuc te ciia qua trinh phun Trong trudng hop ap luc tdi da ciia may due khdng dii thi phai chon may due Idn ban Luu ap la giai doan cua qua trinh phun nhua vao khudn - tiep sau giai doan phun Trong giai doan bao ap, nhua se tiep tuc duoc phun vao khudn de lap day phan cdn thieu cua giai doan phun va bu mdt phan vao lupng nhua da bi co ngdt ngudi May diic se im tien dieu chinh ap luc, chu khdng ' CHI CO KHI VIET NAM, Sd 1+2 nam 2014 www.cokhivietnam.vn IGHIENcuu-TRAODOI tigu chinh theo van tdc d giai doan nay, dd giai ban gom thdng sd la thdi gian va ap luc * Ap luc day sau: Ap luc diy sau la ap luc tac dyng vao phia sau rue vit diln nhua nguyen lieu vao xylanh de len phan nhua da duoc nap chat hon, cd tac dung tiy hoi nude lin nhua ve phia pheu va thiic liy viec lam mSm hda nhua khd luu ddng, lam rdn mau diu va phan tan deu chat tao mau rudng hop phoi hpp vdi chat tao mau diing mau did Ap luc nhd hon ap luc phun rat nhieu Nhiet xy lanh 245''C Tficdoquay 125 v/ph Khoang nap nhira 1.5D Nhua GP-PS 100 "^ 200 Hinh 6: Phdn bd dp luc nhua tdc dung len khuon Theo hinh thi luc kep khudn yeu cau (F, tar luc - tf) > ap luc trung binh (P, tf/cm^) x dien tic! hinh chilu cua san phim (A, cm^) x (1/1000) 300 Ap lire day sau, kgf/cm^ Hinh 5: Quan he giiea dp luc day sau vd khd ndng mem hoa nhua ABS [2J Gia tri ap luc sau phai duoc thiet lap sau xem xet van tdc quay ciia true vit, nhiet xy lanh va chung loai nhua Khdng nen thiet lap qua Idn vi se lam cho nhua trao ngoai vdi phun va ranh rdt va kha nang mem hda se giam di, lam phat sinh nhiing bat lai cho may mdc * Luc kep khudn Khi nguyen lieu phun duac phun vao khudn thi ap luc nhua se tac dung vao khudn lam cho khudn cd xu budng bi day va gay hien tuong bavia phat sinh Do luc kep khudn phai Idn hon ap luc nhua Viec tinh toan ap luc tmng binh khuor la rit khd ton thit ap luc tren dudng di ciii nhua qua trinh phun, vi vay, cd the lay luc trung binh bang khoang 60% cua ap luc phui thuc te Idn nhat de tinh toan tuong ddi Gan daj ngudi ta sir dung sensor de ap luc thuc te tron] khudn, dd them khoang 10% ty le an toan kh tinh toan Bdng Ap luc khudn Chiing loai san pham diic Ap Iwc khud (kgf/cm^) Hang tap pham, hang diing hang 250+400 San pham cdng nghiep thdng thudng 400-600 San pham dac chung, san pham mdng I TAP CHi CO KHi VIET NAM, So 1+2 nam 2014 www.cokhivietnam.vn >600 NGHIEN CirU-TRAO DOI c) Thai gian phun - luu dp, thai gian Idm ngugi de san pham due duoc ddng cirng va nhiet dd xudng dudi nhiet bien hinh de dam bao * Thdi gian phun binh dang san pham day khdi khudn Thdi Thdi gian phun (thuc ti) la khoang thdi gian gian chiem ty le Idn nhat chu trinh due true vit tiln len phia vdi phun tir vi tri can nguyen (khoang 40%)-50%) YIU to anh hudng Idn den lieu den vi tri chuyin doi giua van toe va ap luc (vi thdi gian lam ngudi la dd day san pham, nhiet dd tri VP) dl phun nhua mIm hda chay vao khudn xy lanh, nhiet dd khudn, Thdi gian phun thudng rit ngin khoang dudi d) Tdc dp phun tdc quay cua true vit, tdc giay den vai giay nhung lai la thdng so quan ddng ma khuon quyet dinh ngo&i binh san phim diic Thdi gian phun phu thudc vao khoang phun va van tdc phun ciia mdi khoang tuong ling, vao mdi tuong quan giua ap luc phun ly thuyet va gidi ban ap luc phun Idn nhat cai dat, vao mdi tuang quan giua thdi gian phun ly thuyet (tinh theo khoang phun va van tdc phun) va gidi h&n thdi gian phun Idn nhat cai dat Khi thdi gian phun ly thuyet keo dai thi qua trinh phun se bi dirng lai sau dat den gidi han thdi gian, tiic la dirng lai chua phun du luang nhua can thiet vao khudn Do can thiet phai cai dat gidi han thdi gian phun Idn hon thdi gian phun ly thuyet * Thdi gian luu ap Thdi gian luu ap la thai gian tri ap luc sau giai doan phun Vdi muc dich nay, day la thdi gian vira dl tri ap luc nhua d khudn vdi gia tri thich hop cho den cong khudn bj ddng cung lioan toan, vira la thdi gian dl lam ngudi san pham Viec thiet lap thdi gian duoc quylt dinh 3di dp Idn cua san phim (luong phun) va dp Idn ;ua cdng khudn Thdi gian luu ap thudng bing lo^c Idn ban thdi gian phun Giai doan phun cd juan he chat che vdi hinh dang san pham, giai toan luu ap cd quan be tdi kich thudc va dp chinh cac hinh dang cua san pham * Thdi gian lam ngudi: Thdi gian lam ngudi la thdi gian can thiet * Tdc phun Van tdc phun la van tdc tien len cua tryc vit de day nhua ndng chay chay vao khudn Khi phun mdt luong the tich nhua cd dinh thi van tdc cua ddng nhua se ty le nghich vdi tiet dien mat cat ma nd di qua, tire la van tdc thuc te ciia ddng nhua chay tai cac vi tri khac khudn se khac va khac vdi van tdc phun ciia true vit Do dd thuc te ngudi ta thiet lap nhieu khoang phun vdi cac tdc dd phun de dieu chinh van tdc ciia ddng nhua cho phu hop vdi cac vi tri ranh rdt, ranh dan, cdng khudn va binh dang san pham Tdc dd phun tai cdng khudn duoc dat thap de tranh hien tuong chay nhua, sau dd tang len de tranh cac hien tuong vet ddng, thieu nhua Tuy nhien, neu van tdc phun d khoang qua cao se gay cac loi vet den, vay bac hoac bavia Va van tdc phun d cudi san pham lai giam xudng de cd dii thdi gian de thoat ngoai, tranh bien tuong thieu nhua hoac bavia Xem xet tu tinh chat thdng thudng cua nhua cho thay nhua tinh luu ddng ciia nhua ndng chay giam rat nhanh d khudn su giam nhiet do, nen ve co ban tdc dp phun cang nhanh cang tdt, dac biet, ddi vdi cac san pham cd mdng Ddi vdi cac loai nhua tinh the nhu POM, PBT, dai nhiet dd ndng chay rat nhd nen tdc phun phai rat nhanh Nguoc lai, ddi vdi nhua cd tinh dn dinh TAP CHI CO KHI VIET NAM, So 1+2 nam 2014 www.cokhivietnam.vn NGHIEN ClfU-TRAO DOI nhiet nhu nhua vinyl clorua cirng, tdc dp phun nhanh, gja nhiet phu thudc vao ddi khang luu ddng cua nhua, la nguyen nhan gay Idi vet den, vl vay ciing cd trudng hop tdc phun thap * Tdc dp quay ciia true vit De nap nguyen lieu, true vit se quay de day nguyen lieu tir day pheu d phia cudi true vit di chuyen doc theo ranh ve phia dau true vit Tdc dp quay cua true vit la yeu to quan trpng anh hudng den kha nang mem hda nhua nguyen lieu Khi true vit quay, su nhao trdn nguyen lieu xay tao su phat sinh nhiet ma sat thiic diy qua trinh mem hda Tdc dp ddng md khudn thudc vao chiifio loai may diic ma cd the dieu chinh dupc ho^t khdng the khdng dieu chinh dupc, nhung thoM thudng se cd trinh tu ddng tac nhu sau Nghien cihi thyc nghiem [3] Bat dau dong (toe cham) Tien tnrffc (toe 6e cao) Mcf khuon (toe thap) Xiet khuon (toe thip) Lui sau (toe cao) ' D3y (toe dp lh§p) San pham ch8 tao la chi i\k banh rang nhua ky thuat (hinh 8) Ban ve chi tiSt cua chi tiSt bail rang duoc th6 hien tai lieu [3 ] San phim hanh rang nhua duoc su dung h? th6ng truyen dong ciia may in hay banh rang hong bg d6ng ho cong to met cua to, xe may, Nhiet xy lanh ^ 50 * Tdc dp ddng md khudn 100 Tdc quay, v/ph Hinh 7: Quan he giua tdc quay cua true vit vd khd ndng mim hda [2] Ndi chung tdc dd quay cua true vit cang cao cang tdt, nhung khdng nen qua cao vi gay qua nhiet Ngoai ra, nhung loai nhua cd tinh dn dinh nhiet kem nhu nhua vinyl chloride, nlu so lan quay cao se lam phat sinh chay va phan giai nhiet nen phai thiet lap so lin quay thip Doi vdi nhua cd dp dinh cao nhu nhua poly carbonate hay methacrylic thi cung nen &k, tdc quay thip Hinh 8: Chi tiet bdnh rdng nhua ky thugt Banh rang thudng duoc thiit IcS voi cac c4p chinh xac theo tieu chuan JIS B1702-3 2008 Tieu chuan quy dinh vi dung sai cua TAP CHf CO KHi VIET NAM, S6 1+2 nam 2014 www.coldiivietnam.vn NGHIEN cuu-TRAODOI mot buac rang theo cac cip chinh xac hi P4 Bdng Mot so thong sd che dp phun ep den P12 Theo do, cac hanh rang duong Icinh nho hon 20 mm va ciip chinh xac trung binh thuong Duong kinh vong dinh dimg hi P7 den PIO se co dung sai mot buoc rang (mm) nlm dai hi 10+29 |jm 20,59 20,69 20,79 Nhiet lam mat (°C) 50 60 70 Nhiet nong chay (°C) 150 165 180 goi la nhua polyaxetal, la mot loai nhua nhiet deo Thofi gian lam lanh (s) 4,5 7,5 tren co so andehyt fomic (CH^O) Thai gian giii (s) 0,2 1,2 2,2 Ap luc giii (MPa) 96 106 116 Vat Ueu nhua duoc sir dung dl chj tjo banh rang la nhua PolyOxyMetylen (POM) hay Ket qua nghien ciiu [3] da cho thiy, dieu Iden t6i uu de c h i tao san phim nhua POM tren thi nghiem ep phun bao g i m Thoi gian lam day khuon 1,5 giay, ap suiit phun 75 MPa, nhiet KET LUAN chay (phun) 215°C va nhiet long khuon 75°C Dieu kien diic bao gdm rat nhieu cac thdng sd Thai gian lam ngupi duac xac dinh 15 giay d i can phai cai dat Tiiy thudc vao ban chat nguyen dam bao co ngot thap va gia hop ly lieu sir dung, binh dang va kich thudc san pham, Nghien ciiu duoc thuc hien voi loai banh rang nhu hinh va co duofng kinh vong dinh lan ket cau khudn, loai may due sir dung ma thilt lap cho phu hop luat la 20,59 mm; 20,69 mm va 20,79 mm thi Giai doan phun bao gdm nhieu thdng sd cd de dat duac cac chi tiet banh rang co chat luong quan he lan rat phiic tap Khi lap dieu kien tot, cac thong so che phun ep duoc cho due phai dam bao van tdc phun duac uu tien d giai bang doan phun va ap luc bao ap d giai doan luu ap.'t* Ngay nhan bai: 14/01/2014 Ngay phan bien: 16/02/2014 Ngirdi phan bien: PGS,TS Dinh Van Chien, Trudng Dai hpc Md - Dja chat Tai lieu tham khao: 1] Sumitomo Injection Molding Machine Instruction Manual, Sumitomo Plastics Machinar^-, 2012 2] JSW Injection Molding Machine Instrucrion Manual, Japan Steel Work Co., Ltd, 2011 3], Nghien ciiu cong nghe san xuat linh kien nhua ky thuat cd chinh xac cao phyc vu cho mot so igbanh cdng nghiep, de tai nghien ciiu khoa hgc cip Nha nude, ma so KC.03 13/11-15, Chii nhiem de tai rS Truang H6ng Mmh, 2013 TAP CHI CO KHi VIET NAM So 1+2 nam 2014 www.cokhivietnam.vn ... Dinh Van Chien, Trudng Dai hpc Md - Dja chat Tai lieu tham khao: 1] Sumitomo Injection Molding Machine Instruction Manual, Sumitomo Plastics Machinar^-, 2012 2] JSW Injection Molding Machine Instrucrion... thiic diy qua trinh mem hda Tdc dp ddng md khudn thudc vao chiifio loai may diic ma cd the dieu chinh dupc ho^t khdng the khdng dieu chinh dupc, nhung thoM thudng se cd trinh tu ddng tac nhu sau... (toe thip) Lui sau (toe cao) '' D3y (toe dp lh§p) San pham ch8 tao la chi i\k banh rang nhua ky thuat (hinh 8) Ban ve chi tiSt cua chi tiSt bail rang duoc th6 hien tai lieu [3 ] San phim hanh rang