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)

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