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 nghie
Trang 1NGHIEN 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 cua cdc vimg trong xy lanh, nhiet dp khiidn, dp luc phun, dp luc ddy, luc luc kep khuon, thdi gian phun, thai gian hni dp thai gian Idm nguoi, tdc dp phun, tdc dp quay ciia due vll, tdc dp ddng md khuon din chii luang ciia chi tiet nhua ky thugt Tir do dua ra cdc khuyin cdo cho cdc nhd chi tgo cdc linh kien nhua
ky thugt Bdy Id cdc kit qud duac diic kit ra tii qud trinh nghien cuu vd chi tgo cdc chi tiit nhua cdu do 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 temperature ofthe regions in cylinder, molding temperature, infection pressure, molding clamp force, injection tim pressure holding time, cooling time, injection velocity, rotatipn velocity of screw, closing and opeuing veloci^ on quality of technical plastic parts From thatpoini this paper gives the recommendations for
•"'' 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
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Trang 2NGHIEN 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 ra 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
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
2 ANH HlTOTVG CUA CAC THONG SO DEN CHAT LlTONG CHI TIET DUC
a) Nhiet do sy lanh va nhiet do 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 nay la cac dai gia nhiet diing dien trd (Band Heaters) bd tri xung quanh xylanh cua may diic phun (hinh 1)
Pheu cap b^u
Dm gia nhiit Xy-lanh
Hinh 1: He thong Idm nong chdy hgt nhua nguyen lieu
Nhua tir phlu chay vao xy lanh va chai qua 3 giai doan nap - nen - ndng chay, vi vay nhiet do xy
inh nen duac thi^t lap tir thap den ndng chay Nhiet dp mdi viing each nhau khoang S-IS^C sao cho dat
bua luu d phia trude diu true vit dat din nhiet do ndng chay mong mudn ^
TAP CHi CO KHi VIET NAM So 1+2 nam 2014
Trang 3IGHIENCIJU-TRAO DOI
Dai nhiet dp nong chdy ciia nhua khd rpng, do dp vdi sdn phdm cd chiiu ddy mdng nen due i miin nhiet dp cao di tdng dp chdy hdng di phun nhanh vda khudn
.c
>
1
A
'Can
- (25%L) -^
\eu
Nhiet ap nong chay, Tnc
\ r ~(5-io)
1 T n t
Nap
-(5-lS)
50°C ~ 80°C
•
Hinh 2: Cach thiet lap nhiet dp xy lanh
Nhiet do ldiu6n hi anh huong Ion bdi chu trinh diic, do co ngot, tinh chit va hinh dang san pham, Nhiet do ldiu6n du(?c Idem soat thong qua bo phan dieu tiet nhiet do Ichuon (nuoc, dau,.,,), nhung Idia
voi \dhm soat nhiet do 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 1 Nhiet dp xy lanh vd nhiet dp khudn ciia mot sd logi nhua [I]
Nhya
Poly etyrene
Poly propyrene
Poly styrene Thong thuong
Kho chay Nhua AS
NhuaABS
Nhua methacrylic
Poly chloride Vinyl
Poly amide (66)
Poly acetal
Poly carbonate Thong thuong
Co thiiy tinh
Nhiet dp xylanh (°C)
1 4 0
1 8 0
1 5 0
1 8 0
1 7 0 -
180 300 -300 -300 -210
- 2 9 0
- 2 5 0
180 - 260
1502 5 0
-175
270
280
- 1 9 0
- 3 0 0
- 2 1 0
- 3 0 0
- 3 1 0
Nhi$t dp khuon ("C^,
34 + 65
2 0 ^ 8 0
40 + 70
40 + 70
40 + 80
50 + 70
5 9 - 9 5
50 + 70
60 + 120
60 + 100
70 + 120
40 + 100
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Trang 4NGHIEN CIJU-TRAO DOI
^-^- Nhua
PPE cd tinh thay ddi Thdng thudng
Cd thuy tinh PBT
PPS
PES
Nhiet dp xylanh (»C)
240 + 260
280 + 310
230 + 270
310 + 340
340 - 380
Nhiet dp khuon (°C)
40 + 60
40 + 100
50 + 120
1 2 0 + 1 5 0
1 1 0 + 1 5 0
b) Ap luc phun, dp luc ddy vd luc luc kep khudn
* Ap luc phun
VP S ( - 1 < >
- 1 1
[ ^
<
0
1
Hinh 3: Ap luc thuc te ciia nhua tiong
qud trinh phun
Ap luc phun la trd luc do nhua ndng chay
trong xy-lanh bi nen ngan can true vit tien len
trong qua trinh phun nhua, kgf/cm^ Ap luc nay
khdng phai la ap luc cua nhua trong pbin tao hinh
san phim trong khudn, ma do di qua ranh rdt,
ranh din nhua, cdng khudn, nen thuc t8 trong
qua trinh nay da mit di luang ap luc rat Idn
Miic do mat ap luc cirng khac nhau 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 ha 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
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, do dd may due chi quan ly ap luc phun Idn nhat
A p Ivc p h u n giiM h^n
Hinh 4: Quan he giiia van tdc phun vd dp lire phun
Gidi han ap luc phun Idn nhat la ap luc gidi ban cho phep Idn nhat trong toan qua trinh phun Neu
ap luc phun thuc te dat den gia tri nay 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, khi 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 2 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 do ngudi May diic se im tien dieu chinh ap luc, chu khdng
' CHI CO KHI VIET NAM, Sd 1+2 nam 2014
Trang 5IGHIENcuu-TRAODOI
tigu chinh theo van tdc d giai doan nay, do dd giai
ban nay gom 2 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 khi diln nhua nguyen lieu vao xylanh de
len phan nhua da duoc nap chat hon, cd tac dung
tiy hoi nude lin trong 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 trong
rudng hop phoi hpp vdi chat tao mau diing mau
did Ap luc nay nhd hon ap luc phun rat nhieu
Nhiet do xy lanh 245''C
Tficdoquay 125 v/ph
Khoang nap nhira 1.5D
Nhua GP-PS
100 200 300
"^ 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 khi
xem xet van tdc quay ciia true vit, nhiet do xy lanh
va chung loai nhua Khdng nen thiet lap qua Idn
vi se lam cho nhua trao ra 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 trong
khudn thi ap luc nhua se tac dung vao khudn lam
cho khudn cd xu budng bi day ra va gay hien
tuong bavia phat sinh Do do luc kep khudn phai
Idn hon ap luc nhua
I TAP CHi CO KHi VIET NAM, So 1+2 nam 2014
Hinh 6: Phdn bd dp luc nhua tdc dung len khuon
Theo hinh 6 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)
Viec tinh toan ap luc tmng binh trong khuor
la rit khd do ton thit ap luc tren dudng di ciii nhua trong qua trinh phun, vi vay, cd the lay ai 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 do ap luc thuc te tron]
khudn, khi dd them khoang 10% ty le an toan kh
tinh toan
Bdng 2 Ap luc trong khudn
Chiing loai san pham diic
Hang tap pham, hang diing hang ngay
San pham cdng nghiep thdng thudng
San pham dac chung, san pham mdng
Ap Iwc trong khud
(kgf/cm^)
250+400
400-600
>600
Trang 6NGHIEN CirU-TRAO DOI
c) Thai gian phun - luu dp, thai gian Idm ngugi
* Thdi gian phun
Thdi gian phun (thuc ti) la khoang thdi gian
true vit tiln len phia vdi phun tir vi tri can nguyen
lieu den vi tri chuyin doi giua van toe va ap luc (vi
tri VP) dl phun nhua mIm hda chay vao khudn
Thdi gian phun thudng rit ngin khoang dudi 1
giay den vai giay nhung lai la thdng so quan trong
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 khi dat
den gidi han thdi gian, tiic la dirng lai khi chua
phun du luang nhua can thiet vao khudn Do 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 duy tri ap luc sau
giai doan phun Vdi muc dich nay, day la thdi gian
vira dl duy tri ap luc nhua d trong khudn vdi gia
tri thich hop cho den khi cong khudn bj ddng cung
lioan toan, vira la thdi gian dl lam ngudi san pham
Viec thiet lap thdi gian nay 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
de san pham due duoc ddng cirng va nhiet dd
ha xudng dudi nhiet do bien hinh de dam bao binh dang san pham khi day ra khdi khudn Thdi gian nay chiem ty le Idn nhat trong chu trinh due (khoang 40%)-50%) YIU to anh hudng Idn den thdi gian lam ngudi la dd day san pham, nhiet dd
xy lanh, nhiet dd khudn,
d) Tdc dp phun tdc do quay cua true vit, tdc
do ddng ma khuon
* Tdc do 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 nhau trong khudn se khac nhau va khac vdi van tdc phun ciia true vit Do
dd trong 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 nay qua cao se gay ra cac loi vet den, vay bac hoac bavia Va van tdc phun d cudi san pham lai giam xudng de khi
cd dii thdi gian de thoat ra 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 khi d trong khudn do su giam nhiet
do, nen ve co ban tdc dp phun cang nhanh cang tdt, dac biet, ddi vdi cac san pham cd thanh mdng
Ddi vdi cac loai nhua tinh the nhu POM, PBT, dai nhiet dd ndng chay rat nhd nen tdc do phun phai rat nhanh Nguoc lai, ddi vdi nhua cd tinh dn dinh
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Trang 7NGHIEN ClfU-TRAO DOI
nhiet nhu nhua vinyl clorua cirng, do 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 do 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 ra tao
su phat sinh nhiet do ma sat thiic diy qua trinh
mem hda
Nhiet do xy lanh
^
50 100
Tdc do quay, v/ph
Hinh 7: Quan he giua tdc do 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 do quay thip
* Tdc dp ddng md khudn
Tdc dp ddng md khudn tuy 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
3 Nghien cihi thyc nghiem [3]
Bat dau dong (toe do cham) Tien tnrffc (toe Mcf khuon (toe do thap) 3
6e do cao) Xiet khuon (toe do thip)
Lui sau (toe do cao)
' D3y ra (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 nay duoc th6 hien trong tai lieu [3 ] San phim hanh rang nhua nay duoc su dung trong h? th6ng truyen dong ciia may in hay banh rang hong bg d6ng ho cong to met cua 6 to, xe may,
Hinh 8: Chi tiet bdnh rdng nhua ky thugt
Banh rang nay thudng duoc thiit IcS voi cac c4p do chinh xac theo tieu chuan JIS B1702-3
2008 Tieu chuan nay quy dinh vi dung sai cua
TAP CHf CO KHi VIET NAM, S6 1+2 nam 2014
Trang 8NGHIEN cuu-TRAODOI
mot b u a c rang theo cac c i p do chinh xac hi P4
den P12 Theo do, cac hanh rang duong Icinh nho
hon 20 mm va ciip do chinh xac trung binh thuong
dimg hi P7 den PIO se co dung sai mot buoc rang
n l m trong dai hi 10+29 |jm
Vat Ueu nhua duoc sir dung d l ch j tjo banh
rang la nhua PolyOxyMetylen (POM) hay con
goi la nhua polyaxetal, la mot loai nhua nhiet deo
tren co so andehyt fomic (CH^O)
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 do
chay (phun) 215°C va nhiet do long khuon 75°C
Thai gian lam ngupi duac xac dinh 6 15 giay d i
dam bao do co ngot thap va gia thanh hop ly
Nghien ciiu duoc thuc hien voi 3 loai banh
rang nhu hinh 8 va co duofng kinh vong dinh lan
luat la 20,59 mm; 20,69 mm va 20,79 mm thi
de dat d u a c cac chi tiet banh rang co chat luong
tot, cac thong so che do phun ep duoc cho trong
bang 3
Bdng 3 Mot so thong sd che dp phun ep
Duong kinh vong dinh (mm)
Nhiet do lam mat (°C) Nhiet do nong chay (°C) Thofi gian lam lanh (s) Thai gian giii (s)
Ap luc giii (MPa)
20,59
50
150 4,5 0,2
96
20,69
60
165
6 1,2
106
20,79
70
180 7,5 2,2
116
4 KET LUAN
Dieu kien diic bao gdm rat nhieu cac thdng sd can phai cai dat Tiiy thudc vao ban chat nguyen lieu sir dung, binh dang va kich thudc san pham, ket cau khudn, loai may due sir dung ma thilt lap cho phu hop
Giai doan phun bao gdm nhieu thdng sd cd quan he lan nhau rat phiic tap Khi lap dieu kien due phai dam bao van tdc phun duac uu tien d giai 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 do 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