he thong kenh dan nguoi va he thong dinh vi dan huong (autosaved)
Post on 27-Sep-2015
22 Views
Preview:
DESCRIPTION
TRANSCRIPT
H THNG LM NGUI V H THNG NH V DN HNG
H THNG LM NGUI V H THNG NH V DN HNG
TRNG H S PHM K THUT HCM
KHOA O TO CHT LNG CAO
THIT K V CH TO KHUN PHUN P NHA
H THNG LM NGUI V H THNG NH V DN HNG
GVHD:Ths. TRN MINH TH UYN
SVTH: L VN TI MSSV:11144162
Mc Lc
I.H THNG LM NGUI TRONG KHUN P NHA3
1.Vai tr3
2.Cu to ca h thng lm ngui3
3.Phng php ch to v tnh ton h thng lm ngui4
a.Mt s cht lm ngui:4
b. dn nhit ca kim loi4
c.Quy lut thit k knh lm ngui4
d.Lm ngui li khun7
e.Lm ngui lng khun10
f.Cc chi tit s dng trong h thng lm ngui13
h.Tnh ton thi gian lm ngui20
i.Thi gian lm ngui mt s chi tit21
j.Kt lun:22
II.H THNG DN HNG V NH V22
a.Cht dn hng v bc dn hng22
1.Cc loi cht dn hng22
2.Cc loi bc dn hng22
3.Cch lp bc dn hng v cht dn hng24
b.C cu nh v25
1.C cu nh v mt cn25
2.C cu nh v chnh xc bng mt26
c.V tr ca cht v bc dn hng26
TI LIU THAM KHO26
I. H THNG LM NGUI TRONG KHUN P NHA
1. Vai tr
Gim thi gian lm ngui (chim 60% chu k p) nhng phi m bo cht lng sn phm tng nng xut.
Khun c nhit n nh, lm tui th khun cao ln ng thi hn ch ph phm.
2. Cu to ca h thng lm ngui
Hnh 1: Thnh phn h thng lm ngui.
D: Bm
C: ng cung cp cht lm ngui
G: Vch lm ngui
E: Knh dn ngui
F: ng dn
B: Khun
A: B cha dd lm ngui
H: B iu khin nhit
3. Phng php ch to v tnh ton h thng lm ngui
a. Mt s cht lm ngui:
Vd: Cht ng bang (glycol/nc) nhit lm vic -20 0 oC; nc lm lnh 0-90 oCvvv (Bng 1.8/GT.TKCTKPEN, trang 91).
b. dn nhit ca kim loi
Vd: Vt liu lm khun thp Ni Cr 30-60 W/m.k ( dn nhit); nhm 197 W/m (Bng 1.9/GT.TKCTKPEN, trang 91).
c. Quy lut thit k knh lm ngui
Ch dy ca sn phm, b tr knh dn ngui gn thnh dy ca sn phm.
Hnh 2: B tr knh dn ngui lm ng u v khng ng u
Gii nhit tt khi knh dn ngui t gn mt phn khun.
ng knh knh dn ngui khng i.
Mt u vo mt u ra, chnh lch t (1-5 0 oC).
Chia knh dn ngui nhiu vng lm ngui.
Dng cht lm ngui chy lien tc.
B tr lnh dn ngui ng u hai ph core and cavity.
Knh dn ngui phi c khoan c nhm to dng chy ri trao i nhit tt hn dng chy tng 3-5 ln.
Hnh 3: Knh dn ngui khng nn qu di
Dng chy ri Raynold:
Trong :
: t trng ring ca cht lm ngui kg/m3
: h s nht knh lm ngui (m2/s)
: ng knh knh dn ngui (m)
: vn tc trung bnh ca dng cht lm ngui (m/s)
Bng 1: Trng thi dng chy da trn Raynold
Bng 2: Kch thc knh lm ngui cho thit k
Hnh 4: Kch thc knh lm ngui cho thit k
d. Lm ngui li khun
1. H thng lm lnh c vch ngn (Baffe system)
Hnh 5: H thng lm lnh c vch ngn
2. H thng kiu vi phun (Fountain system)
Hnh 6: H thng kiu vi phun
3. H thng lm lnh dng l gc(Angle hole design)
Hnh 7: H thng lm lnh dng l gc
4. H thng lm ngui dng l tng bc(stepped hole design)
5. H thng lm ngui dng xon c(spiral cooling)
Hnh 9: H thng lm ngui dng xon c
6. Cc dng gii nhit khc
Hnh 10: lm ngui bng kh
Hnh 11: lm ngui bng ng dn nhit
PP
Vch ngn
Vi phun
L gc
L tng bc
Xon c
Dng khc
C cu
c im
Lm lnh li nh
Nng xut cao hn
Phn b gii nhit u hn
Kh ch to (Phi b kt trong qt ch to
Tng t pp l gc
ng lm ngui u
Nng xut cao hn
Thanh nhit ngoi gii nhit cn l li khun
ng dn nhit v thanh nhit nc truyn nhi gii nhit cho khun
Ci tin
Ci tin so vi pp vch ngn
D ch to hn,nhng phi c nt bt
Hiu qu nht so vi cc pp
e. Lm ngui lng khun
1. Mt s h thng b tr knh ngui lm lnh trn lng khun
Hnh 12: H thng lm lnh cavity dng trn
Hnh 13: Mt s h thng lm lnh cc dng khc.
2. Cc b tr h thng lm ngui trn lng khun.
Hnh 14: B tr knh dn ngui theo tng knh ring bit
Hnh 15: B tr knh dn ngui dng vng mt cp
Hnh 15: B tr knh dn ngui dng vng nhiu cp
f. Cc chi tit s dng trong h thng lm ngui
1. Cc nt chnh dng (pressure plugs)
Dng kha hay iu khin dng chy ca cht lm ngui theo ca ngi thit k.
Hnh 16: Mt s loi cc nt chnh dng
2. Nt v que lm lch hng dng(driverting plug and rod)
Hnh 17 : Mt s loi nt v que lm lch hng dng
3. Cascade water junction
Dng lm ngui cc li c cy vo khun hoc nhng vng kh thit k knh lm ngui
Hnh 18 : Mt s loi cascade water junction
4. Vch trn (bubbler tube)
L loi ng dng lm ngui nhng li nh c cy vo khun
Hnh 19 : Mt s loi vch trn
5. Vch phng hoc vch xon(baffle or sprical baffle)
Dng lm ngui 2 thnh phn. Vch phng s gip cht lm ngui chy ln xung bn trong cc l khoan v to ra dng chy ri bn trong chng qu trnh lm ngui din ra nhanh hn.
Hinh 20 : Mt s loi vch phng hoc vch xon
6. ng dn nhit (thermal pin)
Dng lm ngui li cy hoc cc li trc trn mt bn.
Hnh 21 : Lm ngui bng ng dn nhit
7. u gi chuyn tip(elblow)
Dng kt ni ng dn cht lm ngui vi knh dn lm ngui
Hinh 22 : Mt s loi u gi chuyn tip
8. u ni(connector)
Dng kt ng dn cht lm ngui vi knh dn lm ngui
Hnh 22: Mt s u ni
9. ng phn phi cht lm ngui.
Hnh 23: ng phn phi
g. Tnh lu lng nc lm ngui
Cn phi bit lu lng nc lm ngui v n trc tip lien quan n ng knh ca knh ngui s c thit k. Lu ln nc lm ngui c tnh:
Q= vi
Trong :
: Tn tht p dc ng trong knh ngui
: H s tn tht
: Tng chiu di knh dn ngui
: ng knh knh ngui
: H s gia tc trng trng.
Suy ra
= vi
Trong :
: nhm tuyt i
: ng knh knh dn ngui
Nhn xt : tn tht p t l nghch vi ng knh knh ngui, ng knh cng ln th s mt p cng nh.
Theo thc nghim : c th da vo bng di y chn cc gi tr ph hp.
ng knh knh dn ngui(mm)
Lu lng nc ti thiu(lt/pht)
8
2.84
10
3.41
14
5.11
16
5.68
20
6.82
25
9.46
h. Tnh ton thi gian lm ngui
Thi gian lm ngui c hiu l thi gian t lc khun bt u chiu tc ng ca p sut gi khun cho n khi khun m ra.
L hm s ca nhit khun, nhit chy do, tnh cht vt liu em phun p, v chiu dy ca sn phm.
Trng hp tnh thi gian lm ngui vi sn phm dy t 1- 4mm, nhit khun di 600C c th s dng cng thc sau:
vi : thnh dy nht ca sn phm.
V d:
, thnh sn phm dy 2.5mm
Trng hp nhit khun cao hn 600C th:
vi
Vi
h : Chiu dy ca sn phm(m)
: khu tn nhit
i. Thi gian lm ngui mt s chi tit
Hnh 24: Thi gian lm ngui mt s dng chi tit
j. Kt lun:
Nhit khun l thnh phn quan trng nht nh hng n nh hnh v cht lng sn phm.
Thi gian lm ngui c xc nh ch yu da vo nhit khun, khng th rt ngn thi gian lm ngui bng cch gim nhit m phi t khu thit k sn phm( dy khng cn thit), thit k khun nha(vt liu khun, knh nha, ng nc lm ngui)
II. H THNG DN HNG V NH V
C rt nhiu pp nh v hai tm khun, ph thuc vo hnh dng ca chi tit, chnh xc ca sn phm, tui th ca khun.
Cc cch chn:
1.Khng s dng nh v trong khun
2.Cht dn hng v bc dn hng
3.Kha cn gia lng khun v li khun
4.Kha cn gia nhm lng khun v li khun
5.Kha nm
6.Kt hp 1 vi 3,4,5 hoc 6
a. Cht dn hng v bc dn hng
Chc nng chnh ca cht dn hng v bc dn hng l a khun su vo khun trc thng hng vi nhau.
Cht dn hng nm khun trc v bc dn hng nm khun sau.
di ca cht dn hng phi di hn ming ghp cao nht tranh hng hc khi ng khun c bit khi lp rp.
1. Cc loi cht dn hng
2. Cc loi bc dn hng
Hnh 25 : Bc dn hng thng khng vai v c vai
3. Cch lp bc dn hng v cht dn hng
Khi cht c ci c trn tm h tr, c th g b t khun m khng g b tm ny. D bo dng
Cht c ci t trn nhanh chng, khi g b t khun chun. Lp rp hon chnh b loi b
Hnh 26: Lp bc dn hng v cht dn hng
Vic lp rp cc cht dn hng trong khun rt quan trng.
Trong mt khun bnh thng c th 4 cht dn hng, n gin 2,3 cht.
Nhng khun lp c ti 6 cht (khc ng knh) trnh gay ra hng hc cho lng v li khun
Bng 3: Bng tra kch thc trc dn hng
b. C cu nh v
Thng thng cc cht dn hng c th gi c mt thng hng s b, nhng vi khun chnh xc th dung sai ca cc cht dn hng l qu ln v th cn c nh v
Sn phm ln phi c b nh v (chu lc p b mt)
1. C cu nh v mt cn
ng dng chnh cho lng khun rng v su vi sn phm thnh mng
trnh bt trn mt cn v nng cao tui th ca khun, nn ti b mt ch tip xc ca mt cn hay lp vo n khi lp ghp ti b mt
Hnh 27: C cu nh v mt cn
2. C cu nh v chnh xc bng mt
Li ch:
Nng cao tui th, li nhun cho vic sa cha
1 Tm khun c nh
2 Nm nh v mt bn
3 tm khun di ng
1 Tm khun c nh
2 Nm hai mt bn
3 tm khun di ng
1 Nm mt bn
2 Nm chng n mn
Mt vt n v chnh xc
Mt vt i v chnh xc
Mt nh v c tm chng n mn
c. V tr ca cht v bc dn hng
Vic dc cc cht v bc dn hng trong khun cng rt quan trng
Hai Phn khun t ngc nhau s gy hng hc lng v li khun
S dng cht ng knh khc nhau(1 cht c k khc hoc 1 l x dch so vi cc l cn li) h thng thn khun tiu chun
TI LIU THAM KHO
THIT K V CH TO KHUN PHUN P NHA( T.S PHM SN MINH THS TRN MINH TH UYN)
SVTH: L VN TI Page 4
top related