i hc nng -

Trng i hc k thutTS. inh Minh Dim

Gio trnh

Kim loi thit b nhit

nng, 2003

i hc nng -

Trng i hc k thutTS. inh Minh Dim

Tm tt bi ging

Phn 2

c kim loi

nng, 2003

i hc nng -

Trng i hc k thutTS. inh Minh Dim

Tm tt bi ging

Chng 4

Gia cng ct gt kim loi

nng, 2003

i hc nng -

Trng i hc k thutTS. inh Minh Dim

Tm tt bi ging

K thut c kh

nng, 2003

Chng 1: vt liu kim loi 1.1. Tnh cht ca kim loi 1.1.1 Tnh cht ho hc Kim loi l cc nguyn t ho hc pha tri bng tun hon Menelep. Kim loi tham gia cc phn ng vi kim; Cu to nguyn t: lp in t ngoi cng d tch khi ht nhn tr thnh in t t do v nguyn t tr thnh ion dng. Ngoi ra trong thc t ch to cc chi tit my ta cn k n tnh chu n mn, tnh chu nhit , tnh chu a xt, . . . ca kim loi v hp kim ca chng. 1.1. 2 Tnh cht vt l Kim loi l vt liu c nh kim; H s gin n nhit khc nhau; C tnh dn in, dn nhit tt; Khi lng ring () v nhit nng chy ( Tonc ) khc nhau; Kim loi c cu trc mng tinh th ; 1.1. 3 Tnh cng ngh Kim loi c bn, do cao, c kh nng gia cng nng hoc gia cng ngui,... c trng cho tnh cng ngh ca vt liu l : tnh c, tnh rn, tnh hn v tnh gia cng ct gt v nhit luyn (gia cng x l nhit). a. Tnh c Tnh chy long cao (nn kh nng in y lng khun tt); C tnh co ngt khi kt tinh (ng c). Tnh thin tch: S khng ng nht v thnh phn ho hc ca kim loi trong vt c. Tnh ho tan kh b. Tnh rn Kh nng bin dng vnh cu ca kim loi khi chu tc dng ca ngoi lc to nn hnh dng nht nh m khng b ph hu. c. Tnh hn Kh nng to nn mi lin kt khng th tho ri c gi l mi hn. d. Tnh ct gt Kh nng cho php gia cng trn cc my ct gt nh: tin, phay, bo, khoan, mi ... Tnh ct gt ph thuc vo nhiu yu t . V d : Thp t cc bon d ct gt hn thp cc bon cao; Gang xm d gia cng ct gt hn gang trng). e. Tnh Nhit luyn : Kh nng cho php thay i c tnh v mt s tnh cht ca vt liu nh qu trnh x l nhit.1. 2 Phn loi vt liu kim loi (n cht)

Theo mu sc Kim loi en Kim loi mu

: Fe; theo [12] cn c Co, Ni, Mn,... ( mu en xm) : Al, Cu, Pt, Au, ....

1

Theo nhit nng chy Nhit Khi lng ring nng chy oC g/cm3 : 1083 8,93 : 1450 8,90 : 1539 7,87 : 1668 4,51 : 1769 21,45 : 1855 6,51 : 1875 7,19 : 1950 6,02 : 2468 8,57 : 2620 10,2 : 2996 16,65 : 3395 19,35 : 419 7,11 : 232 7,29 : 271,3 9,80 : 327 11,34

Kim loi kh chy T nc

Kim loi d chy

Cu Ni Fe Ti Pt Zr Cr V Nb Mo Ta W Zn Sn Bi Pb

Kim loi nh Kim loi qu Kim loi phng x Kim loi him1.3 kim loi mu :

Be : 1284 1,85 Mg : 650 1,74 Al : 660 2,72 Au : 1063 19,32 Ag : 960 10,5 Pt : 1769 21,45 U : 1133 19,0 Ra (radi), Th (thry) Pu (plutoni), Co,... La, Cs (Xzi), Nd (Ndim), Pr (Prascim) ...

Kim loi mu v hp kim mu l kim loi m hu nh khng c cha st. Kim loi mu thng c cc tnh cht c bit v u vit hn kim loi en : tnh do cao, c tnh kh cao, c kh nng chng n mn, chng mi mn, c tnh dn in, dn nhit tt. Cc kim loi mu thng dng l nhm, ng, titan, manh, thic, vng bc v cc hp kim ca chng. Kim loi mu c th phn loi theo mt s c im sau : 1.3.1 Kim loi nng (c khi lng ring >= 5 g/ cm3) g/ cm3 V d : W = 19,35 cu = 8,94 g/ cm3 Ni = 8,92 g/ cm3 Sn = 7,30 g/ cm3 Zn = 7,14 g/ cm3 1.3.2 Nhm kim loi nh 7 %Al ( 1,3 -1,7 %C, 1,3-1,6 %Si, 0,4-1,0 %Mn, 18-25 %Al) . Lm vic n nhit 900 oC.1.6 Thp v cc ng dng ca n

Thp l hp kim ca st vi cc bon v 1 s nguyn t khc trong thnh phn cc bon : C < 2,14%. Ngoi ra cn c mt s nguyn t khc : Mn, Si,... cc tp cht: S, P, O2, N2, H2 1.6.1 Thp cc bon thng dng (hay cn c tn gi l thp cc bon cht lng thng). Chng c chia thnh 3 nhm ( theo TCVN v tiu chun ca Lin x ) Nhm A - m bo v c tnh ca thp; Nhm B - m bo v thnh phn ho hc (cho php hn) Nhm C - m bo c tnh & thnh phn ho hc, dng cho cc kt cu yu cu v cht lng cao nh kt cu hn;... K hiu theo TCVN 1765 - 75 Thp cc bon : ( ngha ca k hiu : CT - C cc bon, T- thp ) 3 nhm A, B, C K hiu theo TCVN 1675-75 Nhm A CT31 CT33 CT34 CT38 CT42 CT51 CT61 C tnh ca thp nhm A: b KG/mm2 32 32 - 40 34 - 42 38 - 47 42 - 52 50 - 62 60 - 72 ch KG/mm2 22 24 26 28 31 5 K hiu theo TCLX % 22 CT0 33 CT1 31 CT2 21 - 27 CT3 25 CT4 15 - 21 CT5 11 - 16 CT6 10 =14,3 >=13,8 >=13,8 12,9-13,2 11-11,7 12,3-13,2 13-13,3 13,5-13,8 12-13

89,5 91,5 90 87,5 88,5 87,0 82 90 88,5 87 89 89

Nhm TiC-WCT15K6 (WCTi15Co6) T5K10 (WCTiCo10)

Nhm TiC-TaC-WCTT7K12 (WCTTC7Co12) TT10K8 (WCTTC10Co8) TT20K9 (WCTTC20Co9)

Ngoi ra cn c mt s nhm vt liu cng nh sau : Nhm vt liu Ccbon - Nitrit - titan [16](trang 208 ) Khi lng ring 5,6 - 6,2 g/cm3 cng 88 - 93 HRC Gii hn bn un 120 - 180 KG/mm2. Nhm vt liu Ccbt - crm + hp kim cng [16](trang 208 ) Khi lng ring 6,6 - 7,0 g/cm3 cng 80 - 90 HRC Gii hn bn un 40 - 70 KG/mm2. Nhm vt liu khng c vnfram [16](trang 208 ) TIC% TiN% 4Ni1Mo Khi lng ring HRA Gii hn bn un THM-20 79% 21% 5,5 g/cm3. 91 115 KG/mm2. THM-25 74 26 5,7 90 130 THM30 70 30 5,9 89 140 KTHM30A 26 42 32 5,8 88 150 Vt liu bt mi v dng c ct Tc l s dng vt liu c cng hn gia cng vt liu mm hn. Bng 1-2Loi vt liu cng Knoop Gii hn bn Mpa = N/mm2 T nc o C HRA

Kim cng Nitrit Bo ( BN) TiC SiC WC Al2O3 SiO2Thp ti so snh

8000 5000 3100 3000 2700 2100 1000 800

7000 7000 2800 1000 5000 3000 1200 1200

3500 1540 3100 2400 2780 2050

93 82 - 90

17

Vt liu siu cng.[2] (trang 469) Bng 1-3Vt liu Kim cng t nhin Kim cng nhn to Loi n tinh th Loi a tinh th Nitri Bo (BN) Loi n tinh th Loi a tinh th KL ring g/cm3 3,01-3,56 3,48-3,54 3,30-4,00 3,44-3,49 3,30-3,40 cng HV 10.000 8.600 -10.000 8.000 -10.000 9.000-9500 7.000-8.000 Gii hn bn MPa 1900-2100 2000 200-800 500 2000-3000 Nhit gii hn ca bn 600-850 850 700 1200 1400

Vt liu kim cng tuy c cng cao nhng b gii hn bi bn nhit (C nhit gii hn ca bn thp ) Vt liu nitrit bo ( BN ) c cng cao v c tnh bn nhit cao nn thch hp vi gia cng c nh khoan tin, phay, phay, ...

1.9 Cc loi thp khc

1.9.1 Thp lm vic nhit thp [12, 16] trang 498) Chc nng cha v vn chuyn cc loi kh lng, hay vn hnh trong cc iu kin c nhit thp : Ni t lng : - 196 oC xy lng : - 183 oC Hydr lng : - 253 oC Hely : - 269 oC Neon lng : - 247 oC Cc cht kh cc bua hydr ho hi : Butan (-180 oC) Metyl ( - 80 oC) Ni chung khi nhit cng thp th bn cng tng nhng tnh do v nht gim. (Bng 89 page 502 ) Thp 10Cr14Mn14Ni4Ti dn nhit : ( 10

Khng bn

Thp khng g crm Cr13 : X13, 1X13, 2X13, 3X13, 4X13, X14 Cr17 : 12X17, 08X17T, 14X17H2, Cr25-28 : 15X25T, 15X28 Thp khng g Cr-Ni 12X18H8, 17X18H9, 12X18H9T, 12X17, 15X25T, 12X18H9 1.9.4 Thp bn axt [12](trang 497) Chng s n mn ca cc mi trng c hot tnh ho hc mnh. ng dng ch to thp hp ph, ht bm, dng c my lnh, thng cha axt,... Cc loi thp ny dng cha cc cht platic, cht do thu tinh, si thu tinh, cc loi axt vi nng v nhit khc nhau . tng tnh chng n mn trong mi trng axit ngi ta cho thm cc nguyn t : (Mo - Cu), (Cr - Ni - Mo), (Cr - Ni - Mo - Cu), V d : H70M (Ni70MoV) XH65MB (CrNi65MOW)Chng 2 : hp kim chu nhit - bn nhit

2.1 Khi nim chung v thp hp kim chu nhit v bn nhit Khi lm vic nhit cao chi tit chu tc ng ca cc yu t:Nhit , tc dng ho hc ca mi trng; tc dng ca p lc; tc dng ca ng sut;cho nn chng phi c cc yu cu c bit so vi cc loi thp cc bon thng dng. 2.2 Yu cu i vi chi tit khi lm vic nhit cao Phi c tnh bn nhit; gi vng c tnh n nh nhit cao; C kh nng chu ti trng ln To cao; Phi c tnh chu nhit tt: tc l c kh nng chng li s ph hu do n mn ho hc ca b mt vt liu trong mi trng kh nhit cao .2.3 Qu trnh xy ho thp

Thp l hp cht ca st v cc nguyn t khc nh Mn, Si, ... nhit cao st trong thp s tc dng mnh vi xy v to thnh mt lot cc lin kt ho hc nh : FeO, Fe3O4; Fe2O3. Khi To < 570 oC Lp xt c 2 vng: Fe2O3 - Fe3O4 Cu trc tinh th ca chng T oC 110 rt phc tp & tc khuych tn vo trong kim loi rt nh. Khi To > 0 oC - Lp xt cha 3 loi: Fe2O3 - Fe3O4 - FeO. Trong lp FeO 570 l lp xt ch yu, lp ny xp nn O2 d khuych tn vo kim loi. bt u hnh thnh lp oxid FeO; T = 100 oC 570 FeO chim khong 95 % trong thnh phn lp oxid T = >0 750 oC 900 800 700 600 5 Fe + 10 15 20 25 30 Fe + FeO 911 oCFeO FeO + Fe3O4 Fe2O3 + % Fe3O4 O

20

Hnh 2-1 Khi lng b xy ho 10 5

Gin trng thi Fe - O2 i[12] (trang 448) mgToC 1100 900Vng chu nhit km

2 1Vng chu nhit

51 400 500 600 Fe3O4 Fe + 700

700 500

10 C

20

30

%

Hnh 2-2

Hnh 2-3 [12] (trang 450)

bn 30

2

20 10

100

300

500

700

900

T

Hnh 2 - 6 S ph thuc ca bn lu (1000 gi) v nhit ca mt s hp kim (page 456 Guliaev). 1 - HK Mo 2 - HK Ni 3 - HK Co 4 - HK Fe-Cr-Ni-Co 5 - Thp stent 6 - Thp chu nhit 7 - HK Ti 8 - HK AlCh :

Mt s kim loi c nhit lm vic T = (0,7 - 0,8 )Tnc ca KL . Mt s kim loi c nhit lm vic T < 0.5 Tnc ca KL . Tnh bn nhit thay i theo hnh Tnh bn nhit ph thuc cc nguyn t c bn trong hp kim. Nhit cng tng th khong tnh bn hp li (hnh trn) c ngha l nh hng ca cc nguyn t hp kim v ch nhit luyn gim xung. 21

Cc c tnh ca vt liu chu nhit khng th nh gi bng mt thng s m phi kt hp nhiu yu t li vi nhau v cc loi vt liu chu nhit c cc yu cu khc nhau ph hp vi tng loi chi tit my. Loi tuc bin thng lm vic trong 10 nm , lng bin dng 1% Tuc bin kh my bay lm vic trong khong 300 - 3000 gi nn ng sut ln hn loi trn. Tn la vt i dng ch lm vic trong vi pht nhit cao , iu kin lm vic rt khc nghit . Tn la cp 1, cp 2 (v tinh phng ln qu o trong vi giy nn yu cu c bn nhit rt cao)V d

2.4 Cc phng php ho bn nhit cao Nguyn tc chung to ra ra cc vt liu c cu trc l tng ( khng c lch mng tinh th ) hoc to ra mt cu trc c nhiu cn tr cho chuyn ng lch trong mng tinh th chng li bin dng do. Trong thc t c th c mt s phng php ho bn vt liu thp nh sau :2.4.1 Ho bn bng dung dch rn

Khi to dung dch rn mng tinh th b x lch, mi lin kt nguyn t trong mng cng bin i do vy gii hn bn c tng ln . Trng hp to thnh dung dch rn ho tan v hn: L (pha lng) To C nguyn t A L+ t1 < t2

ToC nguyn t B

A 50% Hnh 2-7 Gin trng thi 2 nguyn t ho tan v hn Khi th c tnh nhit thng, gii hn bn t gi tr ln nht max ng vi 50% thnh phn cc t nguyn t ca mi loi. max dch v pha nguyn t c nhit cao hn . V vy to dung dch rn c bn cao cn chn dung mi l kim loi c nhit nng chy cao.Trng hp to thnh dung dch rn ho tan c hn:

bn nng ln nht ng vi thnh phn to thnh dung dch rn qu bo ho . 22

2.4.2 Ho bn bng pha th 2 Nguyn l:

Da vo kh nng hm lch (cn tr kh nng di chuyn ca cc phn t phn tn) Cht lng ho bn ph thuc vo phn tn ca cc phn t pha th 2; Cc phn t th 2 phi c tnh n nh cao, chm tch t, hoc phn hu khi tng nhit . Ho bn bng pha th 2 t tit ra t dung dch rn. Trc ht phi to dung dch rn bo ho, sau em ho gi , t dung dch rn s tit ra pha th 2 gy ho bn. Cc pha ho bn l: cc - bt, nitrt; cc pha lin kim loi . ho bn thp bn nng ngi ta hp kim ho nhng nguyn t c ho tan gii hn vi st hoc vi cc nguyn t hp kim khc c mt trong thp nhng pha lin kim loi . Tho mn nht l cc nguyn t: Cr, W, Mo ... ng thi tng c tnh ca thp bn nng cn phi hp kim ho cc nguyn t to cc bt mnh nh Ti, Nb, V ... Cc nguyn t ny c 2 chc nng: To cc - bt mnh n nh cao, khi nung chng tit ra dng phn tn nh mn gy ho bn mnh. Hn ch s tit ra khi dung dch (nn kim loi ) ca cc nguyn t ho bn dung dch rn Cr, W, Mo, ... Cc nguyn t ny cn c mt trong dung dch rn hn l trong pha th 2 . Phng php ho bn bng pha th 2 t tit ra t dung dch rn ch c tc dng trong khong nhit nht nh. nhit cao pha th 2 b tan vo dung dch rn mt tc dng ho bn .Phng php ho bn nh pha th 2 a vo bng nhn to

Cc pha ny hu nh khng tan vo dung dch rn c tnh n nh cao m c a vo bng cc lin kt nhng cc-bt phc tp: (Cr, W, Mo)23C6; (Nb, V)4C3 hoc cc xt Al2O3, MgO, ZrO3 . Cc loi ny thng c trong cc h Al - Al2O3 Ni - MgO Mo - ZrO3

2.4.3 Ho bn bin gii ht

nhit cao, qu trnh khuych tn xy ra rt mnh theo bin gii ht, do vy gy ra thi bn nhanh chng. Cc ht d trt ln nhau, lm tng tc do, gim bn lu. ho bn bin gii ht ngi ta a vo thp bn nng mt lng nh cc nguyn t c tnh hp ph b mt ln lm gim s khuych tn bin gii ht. V mt ny tho mn nht l nguyn t Bo ( B )2.5 thp chu nhit - bn nhit 2.5.1 Thp chu nhit

23

l loi thp c kh nng chng li s n mn ca ca cc mi trng ho cht v mi trng kh khi lm vic nhit cao T > 550oC V d : (page 450 Guliaev) 12X17 (12Cr17), 15X25T (15Cr25Ti), 12X18H9 (12Cr18Ni9), XH32T (CrNi32Ti). Thp khng r ( thp inox) L loi thp chng li qu trnh n mn b mt trong mi trng kh v cc mi trng cng nghip khc. y l mt khi nim c tnh tng i so vi thp thng . Trong thc t mi loi thp c kh nng chng n mn cao trong mt s mi trng nht nh v ngay c trong mi trng n vn b n mn vi tc nh (khng ng k) v c coi l thp khng r. Da vo tc n mn ( mm / nm ) ngi ta chia ra thp khng r thnh cc loi sau : ( page 141 T4 CBapka) (Xem bng ) Trong mi trng n mn yu (khng kh, nc ngt, ... c cc mc n mn nh sau : Thp c tc n mn 0,01 mm/nm, hon ton khng b g; Thp c tc n mn 0,1 mm/nm, c coi l thp khng g; > 0,1 mm/nm , c coi l thp b g; Ghi ch : 1 gam/(m2h) = 0,122 mm/nm Trong mi trng n mn mnh : nh dung dich axit, mui, ... Nu tc n mn 0,1 mm/nm c coi l thp chu axit hay mui tt Nu tc n mn 1 mm/nm c coi l thp khng g t yu cu Nu tc n mn > 1 mm/nm c coi l thp b g. (page 342 VLH ) nh hng ca cc nguyn t hp kim Crm l nguyn t c vai tr quyt nh i vi tnh cht khng g ca thp. Thp khng r thng cha cc nguyn t hp kim: Cr, (Ni). Cr c tc tc dng tng th in cc ca dung dch c ca st lp b mt c th to ra 1 mng mng th ng ho n nh, xt cht trong mi trng xy ho. Thnh phn Cr trong thp phi ln hn 12 %. Cc nguyn t hp kim khc Cht tng tnh chng n mn ca thp; Ci thin c tnh v cc tnh cht khc; Cc tp cht trong thp m khng th tch c trong qu trnh nu luyn Thp khng g crm Cr13 : X13, 1X13, 2X13, 3X13, 4X13, X14 Cr17 : 12X17, 08X17T, 14X17H2, Cr25-28 : 15X25T, 15X28 Thp khng g Cr-Ni 12X18H8, 17X18H9, 12X18H9T, 12X17, 15X25T, 12X18H9 Ni : l nguyn t m rng khu vc stent: X18H9, ... Ti , Nb : Tng tnh chng n mn tinh gii ht 24

Ngoi tnh chng n mn cao thp Cr-Ni cn c cc tnh cht khc nh : bin dng ngui, tnh hn, dai va p, tnh khng t tnh ... Thp khng g stent v stent - fert C bn cao, khng th ti tng bn c nhng c th tng bn bng phng php gia cng ngui. C dai va p v tnh do cao nhit thng v nhit thp (trong mt khong nhit ln). c tnh ca thp ny l : Dn in km; H s dn n nhit kh ln; 0X13, 1X14: c tnh gim chn ng, s dng ch to cnh tuc bin kh v thu in. Thp khng r stent c 2 nhm: 2.5.2 Thp bn axt [12] (trang 497) Chng s n mn ca cc mi trng c hot tnh ho hc mnh. ng dng ch to thp hp ph, ht bm, dng c my lnh, thng cha axt,... Cc loi thp ny dng cha cc cht platic, cht do thu tinh, si thu tinh, cc loi axt vi nng v nhit khc nhau . tng tnh chng n mn trong mi trng axit ngi ta cho thm cc nguyn t : (Mo - Cu), (Cr - Ni - Mo), (Cr - Ni - Mo - Cu), V d : H70M (Ni70MoV) XH65MB (CrNi65MOW)2.5.3 Thp bn nhit

L loi thp c bn cao khi lm vic nhit cao,[12] trang 471) 12MX (12MoCr), 12XM (12CrMoV), X18H10T (Cr18Ni10Ti), X18H12T Cr18Ni12Ti), 0X18H12b (0Cr18Ni12B). Trong thc t c tnh ca cc hp kim ph thuc vo khong nhit lm vic, gi tr ca chng s thay i nu khong nhit ti u m cc vt liu c bn cao chn vt liu cho ph hp. nh hng ca cc nguyn t hp kim ho tan vao thp n bn lu nh hnh bn do 21 14 7 M M Si

Cr Ni 2 3 % Nguyn t hp kim [12] (trang 461) 25

0

1

Hnh 2-8 nh hng ca cc nguyn t hp kim n bn lu ca st KG/mm2 800 600 400 200 200 400 600 800 1000Thp Cr-Ni Hp kim bn nhit ferrit Hp kim bn nhit -Ni

To C(trang 464)

Hnh 2-9 Gii hn bn ca mt s hp kim nhit cao [12]

1- Thp Cr-Ni kt cu c nhit lm vic T < 300 oC 2- HK Niken Ni T < 650 - 900 oC 3- Thp bn nhit stenit T 900 oC Da vo thnh phn ho hc, t chc ca thp ngi ta chia ra cc nhm chnh sau y: Nhm thp Pc-lt 12XM (12CrMo), 12XM (12CrMoV). Nhm thp Martenxt 12XMCP (12CrMoVSiB), X5B (Cr5WV). Nhm thp stent X18H10T (Cr18Ni10Ti); XH77T P (CrNi77TiAlB). HK bn nhit Ni - Co + Cc HK lm ni hi c nhit lm vic T =350 - 550 oC c khi T = 600 - 650oC + Cc HK lm ng ng c nhit lm vic T = 500 - 650 oC + Tuc bin kh , k thut tn la c nhit lm vic T > 650 oC2.5.3 Nhm thp bn nhit pc lt

y l nhm thp bn nhit c hm lng cc nguyn t hp kim thp 26

Khong (4 - 5)% cc nguyn t hp kim. S dng ch yu trong ch to ni hi , cc ng ng dn hi ... Nhit lm vic < (500 - 600) oC Pha chnh l dung dch rn + pha d cc-bt Gii hn bn do l c tnh ch yu ca loi thp ny. (Gii hn bn do l vi bin dng chy 1% sau thi gian nht nh 10.000 h; 100.000 h; 200.000 h; ... Thnh phn ho hc mt s thp pclt: (G.465) C Cr Mo V 12MX (12MoCr) 0,09 -0,16 0,4 -0,6 0,40 - 0,6 12XM(12CrMoV) 0,08 -0,15 0,4 - 0,6 0,25 - 0,35 0,15- 0,30 12XM (12CrMo) 0,09 -0,16 0,8 -1,1 0,40 - 0,60 12X1M (12Cr1MoV) 0,08 -0,15 0,9 -1,2 0,25 - 0,35 0,15- 0,30 V %C CO2 + C ( Hot tnh ) Cc cht mui , cht kch thch thm cc bon cng sinh cc phn ng to ra cc bon hot tnh : Na2CO3 ---> Na2O + CO2 CO2 + C ---> 2 CO BaCO3 ---> BaO + CO2 Cc phn ng trn xy ra lin tc , to nn CO v lin tip sinh ra cc bon " C " hot tnh i vo b mt chi tit cn thm. 37

c im ca thm cc bon th rn l * Thao tc d dng, quy trnh khng yu cu cht ch; * Cht thm d tm; * Khng i hi thit b c bit; * Phm vi s dng rng ri; Nhc im * Kh khng ch cht lng thm; * Cng lao ng cao, iu kin lao ng nng nhc : bi nhiu, nhit cao, ... lm nh hng n sc kho ca cng nhn. * Thi gian thm di, chi ph cho sn xut s ln; * C kh nng lm cho thp c t chc ht to gy kh khn cho qu trnh ti. 3.6.3 Thm cc bon th kh Ngi ta dng trc tip cc cht kh CO, CH4 thm. CH4 2H2 + C ( dng nguyn t) Khi thm ch cn 3 - 5 % CH4 trong khng kh (nng khong 0,8 - 1 % . l u im ni bt ca thm cc bon th kh. Khi thm bng kh CO th yu cu tinh khit ca CO l > 90% u im ca thm cc bon th kh : Nng sut cao, thi gian thm tng i ngn; Cht lng tt, m bo nng cc bon quy nh cho lp thm; D c kh ho v t ng ho nn ci thin c iu kin lm vic trong mi trng c hi. 3.6.4 Thm cc bon th lng Ch p dng cho nhng chi tit b v nng sut thp, iu kin lao ng nng nhc. Cc chi tit my sau khi thm c tin hnh ti 1 hoc 2 ln sau ram. cng trn b mt t phong 60-63 HRC trong li c cng 30-40 HRC. 3.7 Thit b nhit luyn Thit b nhit luyn bao gm cc loi thit b nung gi v khng ch nhit , dng c phc v cho qu trnh cp phi liu ly phi liu sau khi nung, ... y chng ta ch quan tm n cc loi thit b nung hay cc loi l nung phi khi nhit luyn. Yu cu i vi thit b nung Khng ch nhit chnh xc ; ( sai lch cho php trong khong t 5 - 10 oC). Nhit nung phi ng u trong phm vi lm vic. Mi trng kh l phi t b xy ho v t thot cc bon. t c hi, m bo an ton khi lm vic; Vn hnh d dng, d c kh ho v t ng ho ; Phn loi l nhit luyn : Theo cng dng : L , ti, ram, thng ho kim loi,... Da vo khong nhit ca l m mi loi l c th c nhiu chc nng nh l ti, thng ho, ... a s cc loi l bung c nhit cao trn 950oC cho nn c th s dng ti, , ram, ... Theo phng thc lm vic th c l lm vic gin on v l lin tc. Theo ngun nhit th c : 38

L in : L in tr, l cm ng hay l cao tn, L nhit luyn trong cht in phn : nh l mui hai cc, l mui ba cc,... L t : l t than ( nhin liu rn ), l t du ( nhin liu lng ) l t bng nhin liu kh nh cc loi kh t. Theo hnh thc b tr l c loi l t trc tip, l phn x, ... Theo mi trng truyn nhit : c l truyn nhit l khng kh, l truyn nhit bng kh bo v, kh chy, l du, l mui in phn, ...

c tnh k thut mt s l nhit luyn Tn lL ging L bung in tr L bung in tr L mui hai cc L mui ba cc

K hiuH31T LX H15T H60 C25T CBC 35/13

UV 380 380 380 380 380

PKW/h 24 15 60 25 35

T max o C650 650 1200 1200 850 1300

Bng 3-1 Cng dng Mi trng nung nngRam thp, ram cao,... Ti ram, , thm Khng kh cc bon Ti ram, , thm Khng kh cc bon

Ti thp hp kim, 100 % BaCl2 thp gi, dng c ct

S nguyn l cu to mt s l thng dng trong nhit luyn. L bung in tr

Hnh 3-8 S nguyn l l bung in tr 1 - Gch chu la; 2 - Dy in tr; 3 - Chi tit cn nung; 4 - Tm lt kim loi y bng thp chu nhit; L mui hai cc

39

Hnh 3-9 S nguyn l l mui hai cc . 1 - in cc; 2 - Bung nung; 3 - Gch chu la; 4 - Bt cch nhit; 5 - Gch cch nhit; 6 - V thp bo v L mui ba cc

Hnh 3-10 S nguyn l l mui ba cc 1 - in cc; 2 - Bung nung; 3 - Gch chu la; 4 - Bt cch nhit; 5 - Gch cch nhit; 6 - V thp bo v

40

Hnh 3-7 S nguyn l cu to tng l 1 - Bung nung; 2 - Gch chu nhit; 3 - Bt cch nhit; 4 - Gch cch nhit; 5 - V thp bo v

41

chng 4 khi nim chung v qu trnh sn xut c4.1. Thc cht, c im v cng dng ca sn xut c

4.1.1. Thc cht qu trnh c:

c kim loi l phng php ch to cc chi tit bng cch rt kim loi lng vo khun c hnh dng, kch thc c nh hnh trc theo yu cu, sau khi ng c ta c vt c.4.1.2 S qa trnh cng ngh ch to vt c :

B phn phn B k thut k thutNu chy Kim loi Pha ch hn hp lm khun Lm khun Ch to b mu Ch to hp li Lm li Pha ch hn hp lm li

S y khun

S y li

Lp rp khun li khun - Rt kim loi lng vo khun Gang hi liu

Tho d khun, li

Lm sch vt cVt c hng em nu li

Kim tra cht lng vt c

Giao hng

Hnh 4-1 S qu trnh ch to vt c43

4.1.3 c im :

Phng php c c th ch to sn phm t cc loi vt liu khc nhau : kim loi en ( c gang, c thp, ... c kim loi mu : c nhm, c ng, c vt liu phi kim loi : c cc tng t thch cao,... Vt c c th t vi gam n hng tn nh cc thn my ba, cc b my,... Ch to c vt c c hnh dng, kt cu phc tp nh thn my cng c, v ng c v.v...m cc phng php khc kh gia cng hoc khng ch to c (v d : v ng c, cc b my, thn my...) chnh xc v hnh dng, kch thc v bng khng cao (c th t cao nu c c bit nh c p lc). C th c c nhiu lp kim loi khc nhau trong mt vt c. Gi thnh ch to vt c r v vn u t t, tnh cht sn xut linh hot, nng sut tng i cao. C kh nng c kh ho v t ng ho. c cng c s dng trong vic ch to cc sn phm mang tnh ngh thut, trang tr : chn p tr in, chung nh th, c tng i...Nhc im :

Tn kim loi cho h thng rt, u ngt, u hi v do chiu dy thnh vt c ln. D gy ra nhng khuyt tt nh: thiu ht, r kh, ngm x, thin tch, chy ct v.v... iu kin lm vic nng nhc, nng sut khng cao. Kim tra khuyt tt bn trong vt c kh khn, i hi thit b hin i. 1.1.4 ng dng : c c ng dng kh rng ri trong thc t : Sn xut hng tiu dng : soong, cho, tha... Ch to cc b my : nh thn my ba hi, thn my tin, v hop gim tc, v mt, ghi l,... Ch to cc chi tit my : Piston, Xylanh, bnh rng, bnh , bnh li,...4.1.5 Phn loi cc phng php c : a. c trong khun ct :

Theo loi mu : c bng mu g, bng mu kim loi, bng dng quay, bng mu nha,... Theo vt liu lm khun : Hn hp ct - st , hn hp ct xi mng, hn hp lm khun vi nc thu tinh. Khun bng gch sa mt (khun c 1 ln v khun bn vnh cu)b. Cc phng php c c bit :

c trong khun kim loi, c di p lc, c li tm, c trong khun mu chy, c trong khun v mng, c lin tc v.v... Tu theo cc dng sn xut m c cc phng php ph hp. nhng44

nhn chung phng php c trong khun ct vn rt ph bin.4.2 Cc b phn chnh ca mt khun c bng ct:

1.2.1. Khun c :

L h thng cc b phn to ra l rng ( gi l lng khun ) khi rt kim loi lng vo s iu y, ng c v to nn nhng chi tit c hnh dng v kch thc theo yu cu. Khun c l mt b phn quan trng to nn lng khun. Thng thng khun c c to bi hai na hm khun : na hm khun trn v na hm khun di. Na hm khun di thng c lm ngay trn nn xng. Hai na hm khun c lin kt vi nhau bng cc cht nh v. Ngoi ra khun c cn c cc b phn chnh nh : H thng rt, u hi, u ngt, l xin hi,...1 2 3 4 5 6 7 8

9 10

Hnh 1-1 S cu to mt khun c 2 na ( khun ct ) 1 - Hm khun trn; 2,6 - Hn hp lm khun; 3- u hi v u ngt; 4 - Cht nh v hai na hm khun; 5 -Na hm khun di; 7 - L xin hi; 8- H thng rt; 9 - Li; 10- Lng khun.H thng rt l h thng cc b phn rt kim loi lng vo lng

khun. h thng rt gm c : cc rt (cc rt thng, cc rt c mng ngn, cc rt c mng lc x,...) , ng rt, rnh dn kim loi lng, rnh lc x. Hnh dng v kch thc ca chng c la chn v b tr hp l khi lm khun. u hi u ngt : u hi thng c b tr ni cao nht ca khun to iu kin cho qa trnh thot kh t lng khun ra ngoi d dng. u ngt thng c b tr nhng ni tp trung kim loi b p kim loi b thiu ht do co ngt. L xin hi to iu kin thot kh d dng.B mu : bao gm tm mu, mu vt c (mu chnh), mu u hi, mu u ngt, mu h thng rt (Cc rt, ng rt, rnh lc x, rnh dn). Mu vt c to nn hnh dng bn ngoi vt c (Tu theo loi vt c m c th gn thm

gi li,..)45

Li : l b phn to nn l rng bn trong vt c. Hnh dng bn ngoi ca

li l hnh dng bn trong ca vt c. Li thng c rnh thot kh, xng cng vng, gi li. Li thng c ch to trong hp li.Hp li : dng ch to li, hnh dng bn trong ca hp li l hnh dng

bn ngoi ca li. Mu v hp li : c th dng c mt ln, nhiu ln. Khi ch to mu, hp li phi tnh n co ngt ca kim loi, tnh n lng d cn gia cng c hay cc yu cu khc v chnh xc , bng,... Chnh v th, kch thc ca mu v hp li phi c thit lp da trn kch thc ca chi tit. B mu v hp li c ch to t cc loi vt liu g, kim loi, cht do hoc cc cht phi kim loi khc (xi mng, thch cao...) Gi mu dng to nn ch ta ca gi li, gi cho li ng vng trong lng khun. Tm mu : dng kp mu khi lm khun . Khun v li c ch to bng tay hoc bng my. Khun c lm trong hai hm khun, trn nn xng hay bng cc loi khun c bit khc nh khun kim loi,... Ngoi ra khi lm khun ngi ta cn c th t vt lm ngui, gn cng vng cho khun, li,.. lm khun cn c mu, hp li, hm khun v cc dng c khc...Li : l b phn to nn l rng bn trong vt c. Hnh dng bn ngoi ca

li l hnh dng bn trong ca vt c. Li thng c rnh thot kh, xng cng vng, gi li. Li thng c ch to trong hp li. Hp li : dng ch to li, hnh dng bn trong ca hp li l hnh dng bn ngoi ca li. Mu v hp li : c th dng c mt ln, nhiu ln. Khi ch to mu, hp li phi tnh n co ngt ca kim loi, tnh n lng d cn gia cng c hay cc yu cu khc v chnh xc , bng,... Chnh v th, kch thc ca mu v hp li phi c thit lp da trn kch thc ca chi tit. B mu v hp li c ch to t cc loi vt liu g, kim loi, cht do hoc cc cht phi kim loi khc ( xi mng, thch cao...) Gi mu dng to nn ch ta ca gi li, gi cho li ng vng trong lng khun. Tm mu : dng kp mu khi lm khun . Khun v li c ch to bng tay hoc bng my. Khun c lm trong hai hm khun, trn nn xng hay bng cc loi khun c bit khc nh khun kim loi,... Ngoi ra khi lm khun ngi ta cn c th t vt lm ngui, gn cng vng cho khun, li,.. lm khun cn c mu, hp li, hm khun v cc dng c khc...4.3 Hn hp lm khun v lm li

46

Hn hp lm khun v lm li gm: ct, t st, cht kt dnh, cht ph gia, nc v.v... C 2 loi: loi c ( dng) v loi mi ch to. Ct chim t l cao nht trong hn hp lm khun li (90% c khi n 97-98%).4.3.1: Yu cu i vi hn hp lm khun v lm li

Hn hp lm khun li cn c nhng tnh cht sau:a - Tnh do:

L kh nng bin dng vnh cu ca n sau khi b tc dng ca ngoi lc. Tnh do tng khi nc trong hn hp tng n 8%, t st v cht dnh tng, ct c kch thc ht nh.b - bn:

L kh nng chu tc dng ca ngoi lc m khng b ph hu. bn tng khi ht ct nh, khng ng u v sc cnh, mn cht ca hn hp tng, lng t st tng, lng nc tng n 8 %. Khun ti c sc bn nn (68) N/ cm2. Khun kh c sc bn nn (830) N/ cm2. Khi nhit tng n 9000C th sc bn nn tng 23 ln nh gi bn ta dng gii hn bn nn, c tnh theo cng thc sau : =c - Tnh ln:P F

(N/ cm2)

vi : P - lc nn; F- din tch tit din ngang ca mu em th l kh nng gim th tch ca n khi chu tc dng ca ngoi lc. Tnh ln cn thit vt c khng b cn tr khi ng c, trnh c hin tng nt n, cng vnh. Tnh ln tng khi dng ct sng ht to, lng t st t, cht kt dnh t v khi tng cc cht ph nh mn ca, rm vn, phn tru b kh,...d - Tnh thng kh:l kh nng cho php kh thot ra ngoi qua cc k h nh gia nhng ht ct ca hn hp. Tnh thng kh cn c vt c khng b r kh. Tnh thng kh tng khi ht ct to v u, lng t st v cht kt dnh t, dm cht ca hn hp gim, cht ph nhiu v lng nc < 4 %.

nh gi kh nng thot kh ca hn hp lm khun, ngi ta dng thng kh K: vi: K=Q. L 100. F . P. t

=

509,5 p.t

Q : lng thng kh thi qua mu (cm3). L : chiu cao ca mu (cm). F : din tch tit din ngang ca mu (cm2 ) P : p sut ca kh trc khi qua mu (N/ cm2 ) t : thi gian khng kh thot qua mu (pht ) 3 Trong thc nghim, ngi ta ly: Q = 2000 cm ; L = 50 mm; D = 50 mm, do khi th nghim ch cn xc nh thi gian khng kh thot qua mu.G - Tnh bn nhit:47

L kh nng vt liu m bo bn hay kh nng lm vic bnh thng khi nhit cao, (khng b chy, khng b chy hoc mm ra nhit cao). Tnh bn nhit tng khi lng ct thch anh Si02 tng, ht ct to v trn, cc tp cht d chy (Na2O, K2O, CaO, Fe2O3) trong hn hp t.

e - m:

L lng nc cha trong hn hp , c xc nh bng cng thc sau: X=g g1 100% . g

vi: g- khi lng hn hp ti; g1- khi lng hn hp kh ( nhit 105 110 oC). m tng khi lng nc trong hn hp tng, nhng m phi 68% v nu nhiu hn s lm cho sc bn, tnh thot kh gim.F - Tnh bn lu:L kh nng lm vic c lu v nhiu ln ca hn hp, c xc nh: R2 100% . C= R1

vi : R1- sc bn sn c ca hn hp, R2- sc bn sau mt thi gian s dng. Ngoi ra hn hp lm khun li cn cn phi tho mn mt s yu cu khc nh khng dnh mu, bn b mt m bo khng b bo mn khi c, cng, khng yu cu cht dnh cao, khng c hi, gin n nhit thp,... Ngoi ra cn yu cu thnh phn ct, kch c ht ct, thnh phn ho hc ca ct,... Trong thc t khng th tho mn ht cc yu cu nu trn. V vy tu loi vt c m ta chn u tin cc yu cu ph hp.4.3.2: cc loi vt liu lm khun v lm li

Ch yu l ct, t st, cht dnh kt, cht ph v.v...a. Ct:

Thnh phn ch yu ca ct l SiO2, ngoi ra cn c Al2O3, CaCO3, Fe2O3...Phn loi ct

Theo ni ly ct: gm ct sng ct ni. Ct sng ht trn u, tnh ln tnh thng kh tt nhng kh nng kt dnh km. Ct ni ht sc cnh, d dnh bm vo nhau nhng tnh thng kh km. Theo ht: Ngi ta xc nh ht ca ct theo kch thc l ry. S hiu ry gi theo kch thc l ry. B ry chun c 11 ry:Bng 4-1

Tn ct ct th rt to to va nh rt nh

Nhm 063 04 0315 02 016 01

S hiu ry lin k 1 - 063 - 04 063 - 04 - 0315 04 - 0315 - 02 0315 - 02 - 016 02 - 016 - 01 016 - 01 - 0063

Kch thc ht (mm ) 0,4 1 0,315 0,63 0,2 0,4 0,16 0,315 0,1 0,248

mn bt

0063 005

01 - 0063 - 005 0063 - 005 - nh 1K 1C 97 2K 2C 96

0,063 0,16 0,05 0,1(< 0,05)Bng 4-2

Theo thnh phn thch anh ( SiO2):

Loi ct theo Lin X Loi ct k hiu theo VN Lng cha SiO2 (%)Theo thnh phn t st:

3k 3C 94Bng 4 - 3

4K 4C 90

K hiu Theo S lng t st Lin x VN cha trong ct (%) Ct thch anh K C h1 ; > . trong khi lp rp khng b v khun, li gia gi li v khun cn c khe h.Bn v mu

T bn v vt c ngi ta v bn v mu. Kch thc mu tng t nh bn v vt c tr phn tai gi v dung sai ch to mu. Kch thc phn tai gi mu phi k thm khong h s1, s2, s3 gia gi li vi khun v gc vt thnh khun , , ch t gi li. Dung sai ch to mu l sai lch cho php khi ch to mu. Sai lch ph thuc vo vt liu ch to mu, dng sn xut, kch thc mu. lm khun, mu c chia lm 2 na lp ghp vi nhau bng cht nh v. Mt phn mu trng vi mt phn khun. Trng hp c bit mu c th ch to di dng nhiu phn tho ri. Trn bn v mu cn th hin c mt phn mu, cht nh v v cc phn tho ri c ca mu.

Hnh 4-3 Bn v chi tit cn ch to 53

Hnh 4-4 Bn v vt c

Hnh 4-5 Bn v mu ca vt c

bn v hp li

Tu theo phc tp ca li c th lm hp li nguyn, hp li 2 na v hp li tho ri. Kt cu, kch thc, dung sai v cch v hp li tng t nh thit k mu.102+0,87 120+2,87 70+30 52+0,7

40+0,5 R20+0,5

T

D

150+1,15

Hnh 4-3 B mu gi 4.5 Tnh c ca hp kim Tnh c ca hp kim lin quan n cc i lng : tnh chy long, tnh co, tnh thin tch tnh ho tan kh, ng sut c v t chc ca kim loi vt c 4.5.1-Tnh chy long: L mc chy long hay st ca hp kim c, n quyt nh kh nng in y khun v nhn c vt c r nt.54

4.5.2-Tnh thin tch L s khng ng nht v thnh phn ho hc trong tng phn ca vt c hoc trong ni b cc ht ca hp kim. Nguyn nhn Do t trng cc nguyn t trong hp kim khc nhau Do trong tng phn phn ca vt c c s chnh lch p sut gia cc vng vi nhau. Do tc rt gim nhng tc ng c tng; nhit gim; C 2 loi thin tch: Thin tch vng: L s khng ng nht v thnh phn ho hc trong tng vng ca vt c. Thin tch trong ni b ht kim loi: L s khng ng nht trong ni b ht. Thin tch ht do cc nguyn nhn sau: 4.5.3-Tnh co: (trang 145 LT c) Hin tng gim th tch v kch thc (ch yu l chiu di ca vt c) khi ng c. H s co chiu di St tinh khit 2,44 % Thp mm (1,182-2,0) % Gang xm 1,0 % C 2 loi co: lm co v r co. Lm co: L nhng l rng hnh nn, hnh thnh trn b mt vt c. Nguyn nhn l do lp ngoi ng c trc so vi lp kim loi lp bn trong.Lm co kn Lm co trn mt h

a/

b/

Hnh 4 - 6 Cc dng lm co kn (a) v lm co h (b) R co: L nhng l rng nh nm bn trong vt c, nm dc trc thi c v nm di v tr lm co.R co (thng nm ri rc trong vt c v ch yu tp trung pha trn vt c). 55

Hnh 4 - 7 R co trong thi c Gang xm c h s co ngt Thp

1% 2%

4.5.4-Tnh ho tan kh l s ho tan cc kh c trong khng kh hay do s phn hu m,... Cc cht kh c th l : O2, H2, N2, CO, CO2, CH4 vo kim loi lng gy nn r kh. S ho tan khi ph thuc vo nhit . Nhit tng ho tan kh vo vt liu tng. Tuy nhin tu theo tng loi vt liu m mc tng hoc bo ho ca chng s khc nhau. th biu din ho tan kh ca cc cht khc nhau s khng ging nhau. Khi giai on bt u si, kh t kim loi lng thot ra ngoi to nn p lc hi ngn cn s xm nhp ca cc cht kh bn ngoi vo kim loi, lc ny ho tan kh gim. Khi p sut mi trng tng, kh s ho tan vo kim loi nhiu Khi rt kim loi lng vi vn tc ln, hi nc v cc cht kh trong khun thot khng kp lm cho ho tan kh tng. Khng kh ho tan vo vt c l mt trong nhng nguyn nhn gy nn r kh c bit l khi n t trng thi bo ho. Kh nng ho tan kh khi chuyn t trng thi lng sang c c khc nhau (v d ho tan ca nhm nhit nng chy (lng) l 0,69 cm3/100g khi nhit nng chy (c) l 0,036 cm3/100g cho nn khi ng c rt d sinh ra r kh. 4.5.5 ng sut c ng sut sinh ra trong vt c c th do nhiu nguyn nhn Do tc ngui khng u sinh ra ng sut nhit. Do kt cu vt c khng hp l sinh ra cong vnh thm ch nt (nt nng , nt ngui) Bin php phng chng : to iu kin cho qu trnh kt tinh d dng, khng cn tr s co ngt kim loi; Kt cu chiu dy thnh vt c hp l; gim nhit rt v tc rt,...4.6 c gang xm

Gang c nhiu loi, nh gang trng, gang do, gang bin tnh, gang cu, song trong k thut c ngi ta ch yu s dng gang xm (xem trang 328 KT c). 4.6.1 Tnh c ca gang xm: Tnh chy long ca gang xm cao v c %C cao. Tnh chy long ch yu do thnh phn ca gang v nhit ca nc gang ra l quyt nh. co ca gang xm: co ca gang xm thp (1%). Trong qu trnh ng ngui th tch ca gang thay i (c th dng hoc m). Khi nhit gim th th

56

tch gim, khi grafit ho th th tch tng; c 1% grafit ho li lm tng th tch ln 2 %. Trong qu trnh ng c co ngt dao ng trong khong 1-5 %. Tnh ho tan kh ca gang xm: Cc kh ho tan trong gang xm: O2; N2; H2 v hi nc. Hm lng kh trong gang thng c tnh theo cm3/100g hoc theo %. Thng thng tng hm lng kh trong gang khong 6-50 cm3/100g. Trong cn lu hm lng cc cht nit v hydro l mt trong nhng nguyn nhn chnh gy nn r kh ( khi N2 > 12-15 cm3/100g v H2 > 3-4 cm3/100g). Tnh thin tch ca gang xm: Lng cha C; P; S v chiu dy thnh vt c ln th thin tch cng nhiu. Cc cht P, S c th kt hp vi mt s cht khc to nn cc hp cht d chy phn b vng tinh gii ht gy nn thin tch ht. Khi c gang xm cn ch to iu kin cho qu trnh grafit ho xy ra trit v nu khng th cc bon s b gi li trng thi hp cht Fe3C lm cho gang d b ho trng. 4.6.2- Nu chy gang xm Vt liu nu v m liu: Khi nu gang xm phi dng nhng nguyn nhin liu sau: nguyn liu kim loi, nhin liu cung cp nhit; tr dung ; trong sn xut c gi l vt liu nu. Mun nu ra loi gang c thnh phn ho hc ng yu cu, c nhit cao, vn hnh l d dng cn phi tnh ton phi liu cho mt m nu gi l m liu.Nguyn liu kim loi Bao gm gang thi, gang c, thp vn v hp kim ferro.

Bng 4-4 Mc gang Cc bon Silc G0 3,5 - 4 3,26 - 3,75 G1 3,6-4,1 2,76 - 3,25 G2 3,7 - 4,2 2,26 - 2,75 G3 3,8 - 4,3 1,76 - 2,25 G4 3,9 - 4,4 1,26 - 1,75 * Gang thi : Gang luyn thp l gang thi dng cho luyn thp. Thnh phn cc bon trong gang thi cao hn gang c nhng hm lng Si thp. Mt gy ca gang ny c mu trng, t khi dng lm nguyn liu cho c gang. Gang thi hp kim l gang thi c thm cc nguyn t hp kim nh Ni, Cr, Mo, Ti, Cu ,... thng dng phi liu khi c nhng chi tit yu cu c c tnh cao. * Gang c gm gang my (gang my c, thn my c, vt c hng, ...) v gang hi liu (nh u hi, u ngt, u rt, ... Gang vn c c im l t cc bon, hm lng Si cng t hn gang thi. * Gang hi liu : * Thp vn l nhng mu thp , thp hnh, u mu thp khi gia cng ct b ra, ... St thp vn c tc dng gim hm lngcc bon v Si nn thng dng phi liu nu ra gang c c tnh cao thng chim khong (1-10 )%. * Hp kim fero : Bng 4-5 Loi ferro K hiu Thnh phn Si % Mn % Cr % P% S% FerroSilic Si45 40-47 0,8 0,5 0,05 0,0457

Si75 70-80 0,7 0,5 0,05 0,04 Si90 87-95 0,5 0,2 0,04 0,04 Ferro cc Mn0 80 0,5 2,0 0,3 0,03 bon thp Ferro cc Mn1 78 1,0 2,5 0,3 0,03 bon tr.bnh Mn2 75 1,5 2,5 0,35 0,03 Vt liu trc khi a vo l phi c ly theo mt t l nht nh; phi lm sch g v cc cht bn. Kch thc vt liu phi nh hn 1/3 ng knh l ( trnh tc liu) ng knh l ng (mm) 600-700 900-1000 Khi lng thp vn ti a (kg) 10 15 Khi lng gang vn (kg) 15 20 b - Nhin liu Nhin liu dng cho l ng c th l : Nhin liu kh : Kh thin nhin (CH4),... S dng kh thin nhin khng nhng c li v mt kinh t m c v mt k thut v n gim c hm lng lu hunh trong gang v nng cao nng sut l. Nhin liu lng: Du cn Nhin liu rn : Than cc, than gy, than gy nhit luyn Bng 4-6 Loi than Thnh phn % Nhit tr S Tro m Cht bc Than cc 0,6 - 1,4 12 - 12,5 4 1,2 6500-7000 Than gy 1,0 5-7 2 - 2,5 4,5 - 4,9 7255-8535 Than gy NL 0,44 2,4 - 2,7 4,0 - 4,5 1,0 - 1,1 7000-7050 Than gy tuy c nhit lng cao nhng hm lng cht bc ln v bn km. Than gy nhit luyn c bn tng v hm lng cht bc thp. c- Cht tr dung: Khi c cht tr dung kt hp vi tro ca than, gch tng l b chy mn khi nhit cao, cc cht bn ln trong cc nguyn nhin liu,... thnh x c nhit nng chy thp v c tnh chy long cao, d tho x ra khi l trc khi ly gang. Khng c cht tr dung, x s c st kh thi ra ngoi, vic nu luyn gp kh khn, nhit gang nc gang gim. Cc cht tr dung thng dng mang tnh kim: vi CaCO3, (35% khi lng kim loi/M liu); L cht tr dung ch yu khi c bng than gy sng. hunh thch (CaF2): T - 150) oC v gi lu th kch thc ht stenit cng ln, lm cho tnh do ca kim loi gim nhiu, c th to nn nt n khi gia cng hoc gim tnh do ca chi tit sau ny. i vi thp cacbon nhit qu nhit di ng c khong 1500 tr ln. Thp cc bon kt cu (%C 0,4%) 1150 oC Thp hp kim 20X, 40X 1050-1100 oC (TCVN 20Cr, 40Cr) Hin tng ny c khc phc bng phng php . Loi qu nhit nhiu c th phi tin hnh t 2 - 6 ln. Hin tng chy Khi kim loi nung trn nhit qu nhit (gn ng c) vt nung b ph hu tinh gii ca cc ht do vng tinh gii b xy ho mnh lit. Kt qu lm mt tnh lin tc ca kim loi, dn n ph hu hon ton bn v do ca kim loi.Tinh gii ht kim loi

Hnh 5-9 Tinh gii ht b oxy ho v ph hu

Nhit chy ca mt s thp nh sau : Y12, Y13 (TCVN - CD120, CD 130) nhit chy l 1200 oC 45, 2X13 (TCVN - C45,1Cr13) 1350 oC Sau khi b chy th kim loi phi vt i hoc ct b phn b chy.

76

Nt n: Hin tng nt n xut hin bn ngoi hoc bn trong kim loi. Nguyn nhn: Do ng sut nhit sinh ra v s nung khng u, tc nung khng hp l v.v...ng sut nhit ny cng vi ng sut d sn c ca phi (cn, c) khi vt qua gii hn bn ca kim loi s gy ra nt n. i vi thp thng xy ra nt n t0 < 8000C. 5.5.2 Ch nung kim loi Yu cu i vi ch nung l phi tho mn cc yu cu k thut v kinh t. t tnh do cao, khng c khuyt tt v chi ph t. Chn khong nhit nung: Yu cu: m bo kim loi do nht. Kim loi bin dng tt v hao ph t nht. Cht lng vt nung phi c bo m. i vi thp ccbon da trn gin Fe-C chn khong nhit nung khi GCALVng chy Vng qu nhit 1147 911 Vng gia cng p lc 727

Hnh 5-11 S chn khong nhit gia cng i vi thp cc bon Thi gian nung ph thuc vo hnh dng , kch thc, phc tp ca phi, cc tnh cht ca vt liu, phng php nung, phng php xp phi liu vo l , ... Ch nung hp l cn m bo nung kim loi n nhit cn thit trong mt thi gian cho php nh nht. Nhit phi phn b u trn ton b tit din phi. Cn c vo gin trng thi st cc bon ( ng dng cho thp cc bon ) V d : i vi thp cc bon (Thp trc cng tch %C < 0,8%): Nhit bt u gia cng TbGC = Tc - ( 150 ... 200 ) oC Nhit kt thc gia cng Tktgc = TAr3 + ( 20 ... 40 )oC i vi thp sau cng tch:

77

S d phi kt thc di ng Acm v trn Ac1 v: Nu trn Acm th mc d kim loi trng thi 1 pha c tnh do cao , nhng khi ngui s tit ra xmentt (Fe3C) dng li lm gim tnh do. Nu kt thc di Acm th lc gia cng xmentt b v vn ra khi gia cng dng ht nn vt gia cng vn c bn v do cao. i vi thp trc cng tch: Nu kt thc gia cng di ng Ac3 th mc d kim loi trng thi 2 pha nhng pha fe rt c do cao nn vn gia cng c khng nh hng n cht lng sn phm. ng vi mi kim loi v hp kim c mt khong nhit nung xc nh . Chng ta c th tham kho trong cc s tay v rn dp hay gia cng p lc. Thi gian nung Thi gian nung cn phi chn hp l m bo: Yu cu k thut: Nhit phn b u, cht lng vt nung m bo tt khng nt n, khng b bin dng cong vnh, khng c khuyt tt,... Yu cu kinh t: nung chi tit nhanh, khng hao ph nhiu kim loi, nng sut cao, gim lng nhin liu... Thi gian nung ph thuc: 1. Tnh cht ca kim loi ( Tnh dn nhit, tnh dn nhit cao th thi gian nung cng nhanh; 2. Kch thc ca vt nung: Kch thc ln ( tit din ngang ln ) th thi gian nung ln; nhng b mt ln th thi gian nung cn cng nh . 3. Trng thi b mt; Hnh dng ca phi cng phc tp th thi gian nung cng ln; 4. Nhit ca l: Nhit l cng cao th thi gian nung cng nh. Hiu s gia nhit b mt v ca tm kim loi cng ln th thi gian nung cng nh. 5. Phng php xp phi; Thi gian nung c th tnh theo cng thc thc nghim: Khi nung trong l bung :t NUNG = . . K . D 3/ 2

t - Thi gian nung tnh bng gi - h s xp phi; - H s di tng i; D - ng knh hay cnh ngn ca tit din phi - H s nguyn liu: K = 10 Nu thp cha cc bon K = 12,5 K = 20,0 Thp hp kim cao C < 0,4 % C > 0,4 %

(h) (m)

78

Phng php x phi

H s xp phi 1

Phng php x phi

H s xp phi 1,4

2D 1,3

D 1,4 2,0

2

4

Hnh 5-10 S ph thuc thi gian nung v phng php xp phi Cc phng php nung: phi liu khi gia cng p lc : Nung trong cc thit b n gin nh l rn th cng, l phn x, l bung t than, l in, ...5.6 Cn kim loi

5.6.1 Khi nim chung v cn kim loi a. Khi nim : Cn kim loi l qu trnh bin dng kim loi gia hai trc cn c khe h nh hn chiu cao ca phi, kt qu lm cho phi gim chiu cao , chiu di v chiu rng tng. Hnh dng ca sn phm do hnh dng ca khe h gia hai trc cn quyt nh. Cn kim loi c s dng rng ri v n khng ch lm thay i hnh dng ca phi m cn nng cao cht lng phi kim loi : Ph hu t chc kim loi c c nhiu khuyt tt, t chc dng nhnh cy c nhiu r kh, ... to nn t chc mi c chc, ht nh mn cht hn, bn cao, khc phc c cc khuyt tt trong kim loi. b. S qu trnh cn kim loiD RA N T T Ho

C I B A L B H AA

A

1

PA

2

BB

3

Hnh 5-12 S nguyn l cn kim loi 1 - phi; 2 - sn phm; - chiu cao trc v sau khi cn. Ho, H1

3 - trc cn

79

Bo, B1

- chiu rng trc v sau khi cn.

- Chiu di trc v sau khi cn. Lo, L1 Vng ABB'A' - gi l vng bin dng; Cung AB,A'B' tip xc vi trc cn gi l cung n ( hay cung tip xc). Gc - gi l gc n hay gc tip xc; Gc - gi l gc ma st; c. Cc thng s c trng cho qu trnh cn H s ko di H s gin rng H s pL1 Fo = =1 2 Lo F1 B : = 1 Bo 1 Ho : = R H1

: =

Lng p tuyt i : Lng gin di tng i :

H

= Ho - H1 = D ( 1 - Cos )

L B

Lng gin rng tuyt i :

= L1 - Lo = B1 - Bo

d. iu kin cn vo Khi kim loi tip xc vi trc cn ti hai im A A' mi pha ca trc cn tc dng ln vt cn 2 lc : * Phn lc N; * Lc ma st T T = f.N * H s ma st f = T/ N = tg phi i qua c khe h gia hai trc cn lc Tx cn ln hn lc Nx Tx > Nx Tx = T Cos = f.N.Cos Nx = NSin f.N.Cos > NSin > Sin/ Cos > tg m f = tg > tg > Khi t n qu trnh cn thnh (Phi qua khi 2 trc cn), v tr ca lc hng tm P s dch chuyn dn v pha sn phm i ra. Nu p lc ca vng bin dng tc dng ln cung n u nhau v i xng qua trc i qua im gia cung n th phn lc ( lc hng tm P ) s chia vng bin dng ra lm 2 phn v c gc n ' = / 280

==>

f f tg

Khi vt cn vo gia trc cn th gc n s nh dn n khi vt cn hon ton vo trong 2 trc cn th gc n ch cn bng /2 . iu ny chng t khi cn thnh th gc ma st ch cn ln hn /2 cng qu trnh cn hot ng bnh thng. Hin tng ny gi l hin tng ma st tha. bo m iu kin cn vo ng thi s dng ma st tha khi cn thnh ngi ta thc hin mt s bin php nh: Tng h s ma st bng cch khot rnh, hn vt ln trn trc cn, bi cc cht tng ma st,... nhanh chng t iu kin cn thnh ngi ta tng tc cp phi ban u vo trc cn hoc rn nh u phi cn li. Thay i h gia hai trc cn t ln, sau gim dn cho n khi t khe h theo yu cu . Tc l t gc " ln" n " b" . Nh vy qu trnh cn c 3 giai on : Giai on trc cn bt u cun phi. Giai on ny khng n nh, v iu kin bin dng ca phi b thay i lin tc. Giai on cn thnh ( n nh ) iu kin bin dng = const; Giai on kt thc cn khi phi gn ra khi trc cn iu kin bin dng cng thay i. n gin ho khi nghin cu qu trnh cn ngi ta tha nhn mt s yu t lin quan n qu trnh trn nh sau 2 trc cn l hnh tr, c ng knh bng nhau; Hai trc quay cng vn tc gc, (cng s vng quay); C trng thi b mt nh nhau (c ngha l c cng h s ma st); Khng tnh n qu trnh bin dng n hi ca trc cn; Phi c kch thc tit din ngang khng thay i trn ton b chiu di b,h = const Cc iu kin khc cng phi ging nhau ( t chc kim loi, nhit , thnh phn ho hc, cng ngh bi trn, trng thi b mt, ...) 5.6.2. Sn phm cn Sn phm cn rt a dng, c phn ra bn nhm chnh: dng hnh, dng tm, dng ng v dng c bit. Loi hnh: Cc sn phm dng hnh c chia ra Loi hnh n gin : dng (a), gm c thanh, thi tit din trn, vung, ch nht, lc gic, bn nguyt tit din vung , ch nht, trn, lc gic, ... Loi hnh phc tp : dng hnh phc tp (b) c tit din ch V, U, I, T, Z ...

a. Dng hnh n gin

b. Dng hnh phc tp

Hnh 5-13 Hnh dng tit din mt s sn phm cn

81

Loi tm: Mng: Dy: Cun:

Cc sn phm dng tm c phn loi theo chiu dy ca tm thnh: S = 0,23,75 mm; B = 6002200 mm. S = 4,060 mm; B = 6005000 mm; L = 400012000mm. S = 0,22 mm; B = 2001500 mm; L = 400060.000 mm.

Loi ng: Cc sn phm dng ng c phn ra: ng khng c mi hn v ng c mi hn. ng khng hn c cn t phi thi c ng knh = 5426 mm, chiu dy thnh ng S S = 0,540 mm). ng c mi hn c ch to bng cch cun tm thnh ng sau cn hn gip mi vi nhau. Loi ny c ng knh ngoi n 720 mm v chiu dy n 14 mm. 5.6.3 Cc b phn ch yu ca my cn:

1

2

3

4

5

6

5 4

7

Hnh 5-14 S nguyn l cu to my cn1. Trc cn 2. Trc cc- ng 3. Hp phn lc 4. Khp ni 5. Bnh 6. Hp gim tc 7. ng c

Phn loi my cn : Cn c theo s lng trc cn & cch b tr chng + My cn 2 trc; + My cn 3 trc; + My cn 2 trc kp c cng dng nh my cn 3 trc; + My cn nhiu trc; 4, 6,12, 20, ... Theo cng dng + My cn phi; + My cn thp nh hnh; + My cn thp tm; + My cn ng; + My cn c bit nh cn rn, cn bi, cn vnh xe,...

82

Cn C theo s b tr trc cn ngi ta chia ra : + My cn n + My cn ng thng : + My cn 2 cp : + My cn nhiu cp : + My cn bn lin tc : + My cn lin tc :

83

3.6. Ko kim loi

3.6.1. Thc cht, c im v cng dng Thc cht: Ko si l qu trnh ko phi kim loi qua l khun lm cho tit din ngang ca phi gim v chiu di tng. Hnh dng v kch thc ca chi tit do l khun ko quyt nh. c im Ko si c th tin hnh trng thi nng hoc trng thi ngui. C th ko hu ht vt liu kim loi mu, kim loi en, cht do,... C th ko cc sn phm c hay rng bng, chnh xc cao; c tnh c nng cao. Nhc im : Khun mau mn v mn khng u gy h hng sn phm; sn phm d b bin cng nn khi ko nhiu ln cn phi nhit luyn. Cng dng: Ko si dng ch to cc thi, ng, si bng thp v kim loi mu. Ko si cn dng gia cng tinh b mt ngoi cc ng cn c mi hn v mt s cng vic khc.1 2 3 P 4 a) b) 1 2 3

P

Hnh 5-15 S nguyn l kp kim loi a/ Ko si; b/ Ko ng 1- Phi kim loi; 2/ Khun ko; 3 . Sn phm; 4. Nng to ng Khi ko si, phi (1) c ko qua khun ko (2) vi l hnh c tit din nh hn tit din phi kim loi v bin dng theo yu cu, to thnh sn phm (3). i vi ko ng, khun ko (2) to hnh mt ngoi ng cn l c sa ng ng knh nh li (4) t trong phi ko. Cc thng s chnh khi ko si : H s ko di :k= do < [k ] {k] H s ko cho php; d1

[k ] = 1 +

P(1 + f cot g

b

;

Fo, F1- Tit din trc v sau khi ko ln 1;. Mi ln ko tit din gim t (15-35) % ; do, dn - ng knh phi v ng knh sau khi ko ln th n. Lc ko :P = b F1 lg Fo (1 + f . cot g ) F1

84

Yu cu Lc ko phi ln thng cc lc ma st ca kim loi vi khun v lm bin dng kim loi. ng sut ko ti tit din ra khi khun phi nh hn gii hn bn ca kim loi ko. Tnh s ln ko si:k= do d1

d do d d2 = 1 = o ; ; k k k2 lg d o lg d n n= lg kd1 =

d1 =

do kn

Khun ko si v thit b ko si Khun ko si gm khun (1) v khun (2), bin dng l hnh ca khun gm 4 phn: on cn (I) l phn lm vic chnh ca khun c gc cn = 24o360 (thng dng nht l 260), on cn vo (II) c gc cn 90o l ni phi vo v cha cht bi trn, on thng (III) c tc dng nh knh v on cn thot phi (IV) c gc cn 600 si ra d dng khng b xc.Vt liu ch to khun Hp kim cng Thp dng c Thp hp kim1

BK 8, BK12 (theo LX), CD80, CD100, CD130, 30CrTiSiMo, Cr5Mo (theo TCVN).

II

I

IV III

Hnh 5-16 Khun ko1) khun 2) gi khun

Ch : Khi ko phi bi trn. Vt liu bi trn thng dng l grafit, bt vi, bt x phng v parafin1 2 5

Hnh 5-17 S nguyn l my ko si 1- Tang nh; 2- Khun ko; 3- tang qun sn phm ko

85

5.8 p kim loi

p kim loi l phng php lm bin dng kim loi khi i qua khun p c hnh dng v kch thc theo yu cu. 5.8.1 S nguyn l p kim loi1 2 3 4 1 2 4 3 1 2 3 4 5

a)

b)

c)

Hnh 5-17 S nguyn l p kim loi Hnh a : p thun; Hnh b - p nghch; Hnh c - p ng 1) Pistngp 2) Bung p 3) phi kim loi 4) Khun p 5) Nng to l c im :

Trng thi ng sut khi p l nn khi nn c th p cc vt liu km do. Cht lng sn phm p cao Nhc im l lc p ln, ma st ln, nhit cao nn khun mau mn,; kh in y khi p khun phc tp; hao ph nhiu kim loi. Yu cu vt liu ch to khun kp phi bn, chu mi mn. Thng s dng thp hp kim c cha W, V, Mo, Cr v.v...hoc hp kim cng.Cc phng php p :

Khi p thanh, thi ngi ta c th tin hnh bng phng php p thun hoc p nghch. p thun (H. a), kim loi trong bung p (2) chuyn ng ra ngoi cng chiu chuyn ng ca pistng p. p nghch (H.b), kim loi trong bung p (2) chuyn ng ngc chiu chuyn ng ca pistng p. p thun kt cu n gin, nhng lc p ln v ma st gia kim loi v thnh xi lanh lm tng lc p cn thit, ng thi phn kim loi trong xi lanh khng th p ht ln (1012%). p nghch lc p thp hn, lng kim loi cn li trong xi lanh t hn (68%), nhng kt cu p phc tp. H s p:=

S0 S1

Trong S0, S1 l tit din phi trc v sau khi p. Thng thng = 850.

86

5.9 Rn t do

5.9.1. Thc cht, c im v dng c rn t do Rn t do l mt phng php gia cng p lc m kim loi bin dng t do ra cc pha v ch b khng ch b mt trn v di bi ba v e.

1 P 2 3 N

Hnh 5-18 S nguyn l rn t do1 - u ba; 2- Vt rn; 3 - e; P - Lc tc dng

c im: u im C kh nng gia cng rng ri; Vt gia cng t vi gam cho n hng tn. Quy m sn xut a dng t th cng n phn xng v nh my rn dp. Chun b phi cho gia cng c kh : m t, cc cht,... Tit kim kim loi, gm lng d gia cng c kh ; nng cao chnh xc v nng sut ct gt (v d khi ch to bu long, trc khuu,... C th gia cng nhiu loi vt liu khc nhau. Lm thay i t chc kim loi t ci thin c c tnh cho kim loi sau khi rn. Thit b v dng c rn t do n gin, vn u t t Rn t do c dng rng ri trong sn xut n chic hay hng lot nh. Ch yu dng cho sa cha, thay th. Nhc im : chnh xc, bng b mt chi tit khng cao. Nng sut thp thi gian phc v ln, dung sai ln. Cht lng v tnh cht kim loi khng ng u nhau nn ch gia cng cc chi tit n gin hay cc b mt khng nh hnh. Cht lng sn phm ph thuc vo tay ngh ca cng nhn.

87

Dng c C 3 nhm dng c chnh: Nhm dng c cng ngh c bn nh cc loi e, ba, bn l, bn tp, sn, cht, mi t. Nhm dng c kp cht nh cc loi km, t v cc c cu kp cht khc. Nhm dng c kim tra v o lng: ke, thc cp (o trong o ngoi, o chiu su, cc loi compa. 5.9.2.Thit b rn t do Thit b rn t do bao gm thit b to lc, thit b nung nng phi, my ct phi, my nn thng, my vn chuyn.v.v... Rn t do c th tin hnh bng tay hoc bng my. Thit b rn nh cc loi my ba hi dng BH50, BH 75,... My ba hi nc khng kh p, my ba lxo, my ba ma st vn g (l va p), my p ma st (Lc tnh) my rn ngang, my dp trc khuu (nhm my dp) S nguyn l my ba hi7 8 9 10 11 12 13 14 15 6 5

4 3

2 1

Hnh 5 - 18 S nguyn l my ba hi 1- ng c in 2- B truyn ai 3- Trc khuu 4- Tay bin 5- Xi lanh p 6-Pistng p 7- Van phn phi kh 8- Xi lanh ba , 9-Pistng ba 10- thn piston ba 11- u ba 12- e 13- Gi e Nguyn l lm vic ca my ba: ng c 1 truyn ng cho trc khuu 3 qua b truyn ai 2. Thng qua bin truyn ng 4 lm cho pittng p 6 chuyn ng tnh tin to ra kh p bung trn hoc bung di trong xi lanh ba 9. Tu theo v tr ca bn p iu khin 14 m h thng van phn phi kh 7 s to ra nhng ng dn kh khc nhau, lm cho pittng ba 8 c gn thn pittng ba v e trn 10 chuyn ng hay ng yn trong xi lanh ba 9. e di 11 c lp vo gi e 12, chng c gi cht trn b e 13.

88

Khi lng phn ri l phn to ra nng lng va p ca ba. Khi lng phn ri gm piston ba, thn piston ba (8) v u ba (10). Da vo khi lng phn ri m t tn cho my ba hi. V d BH50, BH 75 (tc l my c khi lng phn ri l 50 kg, 75 kg tng ng. My ba lm vic theo ch khng ti, n nht, p lin tc, treo ba, ba p,...

5.9.3. Nhng nguyn cng c bn ca rn t do Nhm nguyn cng chnh : Vut, chn, t l, un, xon, hn rn, p vt,... Nhm nguyn cng ph : Nung nng, lm sch, l phng, nn thng,... a. Nguyn cng vutNguyn cng lm gim tit din ngang v tng chiu di ca phi rn. Dng rn cc chi tit dng trc, ng, dt mng hay chun b cho cc nguyn cng tip theo nh t l, xon, un. Thng thng khi vut dng ba phng, nhng khi cn vut vi nng sut cao hn th dng ba c dng hnh ch V hoc cung trn.

Vut c thc hin bng vic lt phi qua li theo mt gc 900 hay 1800.

5 7 8

3 6

14 2 5 6 9 10

12

a/

Hng dch chuyn phi

b/

Hnh 5-19 S nguyn l cc phng php vut kim loi a) Quay phi mt gc 900 hay 600 b) Quay phi theo chiu xon c . Mt s phng php vut c bit: * Vut trn trc tm: Nhm gim chiu dy v tng chiu di chi tit, ng knh trong ca phi hu nh khng i. Lng phi vo trc tm c cn 3 12 mm/m) v tin hnh gia cng trn e dng ch V v ba phng. Nu trc tm ln th bn trong c l rng dn nc lm ngui nu l ln vut u th trc tm phi nung trc khong 1502000C. Khi vut th vut dn tng on t hai u vo gia d ly chi tit ra khi trc tm.

Ba Chi tit

eHnh 5-20 S vut trn trc tm

Trc

* M rng ng knh trn trc tm:

89

Dng vut cc chi tit dng ng nhm tng ng knh trong, ng knh ngoi, gim chiu dy thnh ng m chiu di hu nh khng i. Trc tm c ng knh nh hn l phi t 50150 mm, chiu di cng tc ly ln hn chiu di phi mt khong 50100 mm. Trc tm cng b th nng sut vut cng cao nhng cng vng km.

P

ba

b

l aHnh 5-21 S m rng l trn trc tm b. Nguyn cng chn Chn l nguyn cng lm gim chiu cao, tng tit din ngang ca chi tit. Cng dng lm thay i dng th trong t chc kim loi gia cng cc u bu lng, l phng cc mt u ca phi, chuyn i kch thc ca phi : tng ng knh khoan sau vut nh li, hoc tng ng knh phi khi cn gia cng trc m khng c phi ln,... Chn c th chn ton b, hoc ch chn cc b tng phn ca phi nh khi chn u lm bu lng. Hng thca kim loi trc v sau khi chn

a)

b)

Hnh 5-22

S chn : a) lm phng mt u, b)thay hng th ca phi

Chn ton b: l nung c chiu di phi, khi chn thng xy ra cc trng hp sau: Trng hp 1: khid0 h0

h0 2 th vt chn c dng hnh trng (a). d0

Hnh 5-23 S chn phi c chiu cao nh

90

Trng hp 2: khi

h0 2 2,5 c th xy ra cc hin tng sau: d0

1. Lc p ln: vt chn c dng 2 hnh trng chng kht ln nhau . 2. Lc p khng ln: vt chn c dng 2 hnh trng kp . 3. Lc p nh v nhanh vt chn c dng loe hai u.

Trng hp 3: khi do b mt n nh.

h0 2,5 vt chn d b cong d0

Hnh 5-24 Hnh dng vt chn ph thuc kch thc v lc tc dng Chn cc b Khi chn ch cn nung nng vng cn chn hay lm ngui trong nc phn khng cn chn ri. Cng c th nung nng ton b ri gia cng trong nhng khun m thch hp.

Hnh 5-25 Hnh dngmt s dng chn cc b Xon l nguyn cng lm cho cc tit din ti ch xon quay tng i vi nhau mt gc quanh trc ca n ( nh khi ch to mi khoan, .. ) Un l nguyn cng lm thay i hng th ca vt rn, lm thay i hng ca trc phi.

Hnh 5-26 Hnh dng phi sau khi un.91

5.10 Dp th tch

5.10.1- Khi nim chung Dp th tch (cn gi l rn khun) l mt phng php rn m kim loi bin dng b khng ch bi cc b mt lng khun. b- c im: bng v chnh xc b mt cao: 0,1 0,05 v bng cao. C tnh ng u v cao, s bin dng thu trit v u khp. C th rn c cc chi tit phc tp, tit kim kim loi, thao tc n gin. Nng sut lao ng rt cao, d c kh ho nn c dng trong sn xut hng lot hay hng khi. b.Phn loi rn khun Phn loi theo kt cu lng khun.3 2 4 5 6

1

Hnh 5-27 S kt cu khun h 1- Na khun di; 2 - Na khun trn; 3- Rnh cha ba via; 4 - Ca ba via 5- Rnh thot kh; 6- Vt dp3 2 4 5

1

Hnh 5-27 S kt cu khun kn 1 -Na khun di; 2- na khun trn; 3- Rnh cha ba via; 4 - Rnh thot kh; 5 Vt dp

92

Rn trong khun h: Khun h l khun c mt phn khun ti vng tip gip vi vt gia cng thng gc vi phng ca lc tc dng, ca ba via khng hn ch s bin dng kim loi ra xung quanh. Xem hnh. Rn trong khun h tnh do thp, s in y khng cao, yu cu cng sut thit b ln. Song mt phn khun tng i n gin. Khun kn: L khun c mt phn khun ti vng tip gip vi vt gia cng song song hay gn nh song song vi phng ca lc tc dng, vt rn khng c hoc nh khng c ba via. Rn trong khun kn th tnh do ca kim loi tng, tnh in thu tt, khng yu cu cng sut thit b ln, song yu cu vic tnh ton phi phi chnh xc, cht lng nung cao. Phn loi theo trng thi nhit ca phi. Rn khun nng: Kim loi d bin dng, kh nng in y tt, khng yu cu cng sut thit b cao, khun mn. Song bng v chnh xc ca vt rn khng cao, khun phi chu nhit tt. Nn dng rn th, rn s b. Rn khun ngui: Ch nung phi gia cng n nhit kt thc gia cng hoc khng nung n c c im ngc li. 5.10.2 Thit b dp th tch thng dng: My ba hi nc-khng kh p rn khun; my p trc khuu; my p trc vt; my p thu lc; ... S nguyn l my p trc khuu dp th tch1 2 3 4 5

6 7 8 9

Hnh 5-28 S nguyn l v nguyn tc vn hnh: 1- M t; 2 B truyn ai; 3 B truyn bnh rng 4- Bnh rng chy lng khng vi trc khuu; 5- B ly hp dng ng m s truyn ng cho my; 6- Trc khuu 7- Tay bin 8- u trt 9- Bn my

93

5-11 dp tm 5.11.1 Khi nim

Dp tm l mt trong nhng phng php gia cng kim loi bng p lc ch to cc sn phm hoc chi tit t vt liu tm, hoc di, cun, bng m chiu dy ca phi t thay i hay thay i khng ng k trong qu trnh gia cng. Da theo trng thi nhit khi gia cng dp tm c phn ra Dp nng : qu trnh dp thc hin trng thi nng, thng s dng khi gia cng nhng tm dy S > = 10 mm, nh thp hp kim, vt liu km do nh Mg,... Dp ngui : qu trnh gia cng tin hnh trng thi ngui (khng nung nng). y l phng php s dng ch yu trong thc t ng dng : Trong cc ngnh cng nghip , c bit l ngnh ch to my bay, my nng nghip, hng tiu dng, t, thit b in,... nh cc phng php : Dp tm, ct hnh, t l, un , dp vut, tp ming, dp dn, mit,... Vt liu dng cho dp tm : Kim loi: Thp cc bon, thp hp kim, hp kim mu nh thp, ng, nhm, ... Phi kim loi: Giy, cc tng, bnt, aming, da, m cc vt liu ny dng tm hay di, cht do, composit, polymer,... 5.11.2 c im chung ca dp tm Chuyn ng ca thit b n gin. C th hon thnh cng vic phc tp bng mt ng tc n gin ca my dp. Ch to c nhng chi tit phc tp, nht l nhng chi tit c thnh mng. Sn phm c chnh xc cao v kch thc, hnh dng v a s khng yu cu gia cng c tip theo. lp ln tt; Sn phm dp c cu trc m bo bn , cng, nh lng tiu hao t kim loi . Tit kim c kim loi, t ph liu; Nng sut lao ng cao nh c trang b cc c cu t ng ho v c kh ho cao nn khng cn cng nhn c trnh chuyn mn cao. ( 30.000 - 40.000 sp/1 ca/ 1 khun ). iu kin lm vic ca ngi cng nhn c ci thin; Do c nhng u im trn m ngy nay dp tm ang c s dng rt rng ri nc ta cng nh trn th gii. 5.11.3 Thit b dp tm Phn loi: Theo nguyn l truyn ng My p trc khuu ( c hc ); My p thu lc;... Theo nguyn tc tc dng lc ca my My tc dng n ( my ch c mt u trt ); My tc dng kp: ( my song ng - c 2 u trt ). Trt ngoi dng gi phi, trt trong dng p su to nn sn phm. My 3 tc dng: ( my tam ng ) ngoi 2 con trt nh trn my cn c u trt th 3 dng y sn phm ra khi khun.

94

My p trc khuu dp tm (C hnh dng tng t my p trc khuu dp th tch (xem hnh 5-28) My p thu lc My c cu to phc tp, lc p ln, tc bin dng ca my n nh khng thay i, khng gy qu ti cho my v c van an ton; My p thu lc thng dng khi ch to nhng chi tit c kch thc ln, phc tp, yu cu cht lng cao. 5.11.4 Cng ngh dp tm Qu trnh gia cng bng phng php dp tm c chia ra 2 nhm nguyn cng chnh: Nhm cc nguyn cng ct: Tc l tch mt phn phi khi phn chung ca n ( ct hnh , t l, ct phi ra tng phn,... ) Nguyn cng to hnh: l nguyn cng lm bin dng kim loi hay dch chuyn 1 phn ca phi i vi phn khc m phi khng b ph hu. Nhm nguyn cng ny bao gm cc nguyn cng: Un, dp vut, tp, dp dn, mit, un vnh, cun mp, ... a. Nhm cc nguyn cng ct: Ct phi l nguyn cng ct ri vt liu ra khi phi theo ng vin bao khng khp kn ( h ) . ct phi c th dng cc my ct sau y: - My ct li dao song song; - My ct dao nghing; - My ct chn ng; My ct tm bng dao song song S nguyn l my ct dao song song nh hnh1 2 3 4 5 6

Hnh 5-29 S nguyn l my ct bng dao song song 1- u trt 2 - Li dao trn 3 - Phi 4 - Li dao di 5 - Bn my 6 - Rnh trt dn hng c im my ct dao song song Hai li dao song song vi nhau, khi ct 2 li dao lun tip xc vi phi trn c chiu di ct.95

Hnh trnh li dao nh . Lc ct ln; lc ct c tnh theo cng thc: P = K.B.S. C Trong : B - Chiu rng ca phi; S - Chiu dy ca phi; K - H s tnh n tnh cht ca kim loi, kch thc khng u ca kim loi, mn ca dao. K = 1,1 - 1,3 C - Gii hn bn ct ca phi ( Tr lc ct ); C = ( 0,8 - 0,9 ) B My c th ct cc tm: rng 3200 mm S (NaBO2)2.2Na(BO2)2 c Tnc = < 1000 oC 2P + 5 Cu2O ===> P2O5 + 10 Cu P2O5 + 3 Cu2O ===> P2O5(CuO)3 Cu + H2 ===> H2O + 2Cu Ghi ch nhit nng chy ca Tnc Cu = 1083 oC; Tnc Cu2O = 1235 oC Tnc CuO = 1336 oC Thuc dng cho hn gang Na2CO3, NaHCO3, K2CO3 Trong gang c cha SiO2 nn khi hn nng chy s xy ra phn ng : Na2CO3 + SiO2 ==> Na4SiO4 + 2 CO2 Thuc hn nhm : AlF3.3NaF Bng 4-1 NaCl 30 45 KCl 45 30 LiCl 15 10 KF 7 15 Na2SO4 3 Khi hn xy ra cc phn ng : LiCl + Al2O3 ==> 2AlCl3 + KCl + Al2O3 ==> 2AlCl3 K2O + H2 O ==> 2KOH 2KOH + Al2O3 ==> 2KAlO2 + H2 NaF + Al ==> AlF3 Hi Na bay ln , chc thng lp xid nhm 3Li2O

+

Na

6.4.2 Kh hn (oxy k thut v cc loi kh chy) a. xy k thut Khi hn kh ta cn xy k thut c tinh khit cao ( 97 ... 99.5 %) cn li c th c ln cc121

tp cht nh Ar, N2, ... Nu tinh khit gim th tiu hao O2 tng ln . V d : tinh khit gim 0.5 % th lng tiu hao c th tng t (5 ... 12) % ( khi tinh khit ca n trong khong (97 ... 99.5) % Cc phng php iu ch kh xy Phng php ho hc

Dng cc phn ng ho hc gii phng xy . Phng php ny cho nng sut thp, khng kinh t , nn n ch dng trong cc phng th nghim.Phng php in phn nc Kt qu s thu c xy v hydro. C 2 m3 hydro s c 1 m3 xy (trong c cha 0.7 % H2) Phng php chng ct xy t khng kh p sut bnh thng cc cht kh xy, nit, argon trng thi lng c nhit si l : Nit (N2) - 195.8 oC oC Argon (Ar) - 185.7 oC xy (O2) - 182.96 Bng cch cho cc cht kh trn bc hi ta ln lt thu c chng. m bo tinh khit cao cn tin hnh chng ct nhiu ln. thu 1 m3 xy cn tiu tn khong ( 0,45 ... 1,6) KW.h Qu trnh thu nhn xy t khng kh c thc hin qua cc giai on: Lm sch khng kh khi cc tp cht ( bi, CO2, hi nc, ...) Nn khng kh t 6 ... 200 at; Lm ngui s b khng kh nn, sau tch xy & nit. Trong qu trnh ny c khi cn thu c NH 3 dng cho my lnh. Gim p sut trong b phn ho lng khng kh ; ( khi gim 1 at th nhit gim 0.25 ... 0.5 oC ); Cho bay hi v tch cc cht kh ra khi hn hp;

4.4 Thit b hn kh Thit b hn kh gm c : Bnh cha kh xy, bnh cha kh axetylen hoc bnh ch kh axetylen hoc cc bnh cha kh chy khc (bnh cha kh metan, ...). Van gim p bnh xy, van gim p bnh axetylen, kho bo him cho bnh ch kh axetylen, m hn, m ct, ng dn kh v mt s dng c km theo.122

4.4.1 Bnh cha khBnh cha kh c ch to t thp cc bon hay t thp hp kim bng phng php dp (dng cho cc loi bnh p sut cao) hoc hn dng cho bnh c p sut thp (bnh cha kh C2H2, NH3. Bnh cha kh thng c dung tch 40 lt. Bnh cha kh xy c p sut 100, 150 v 200 t . Cc loi kh chy nh hydro, mtan, nit, khng kh nn c th cho vo bnh p sut cao (100, 150, 200 t) ring bnh cha kh axetylen, amnic NH3 phi cho vo bnh c p sut thp. Bnh cha kh C2H2 thng c dung tch 40 lt v p sut ti a l 19 t, bn trong c cha bt xp v than hot tnh c tm axetol nhm chng n bnh (mt bnh cha khong 290 - 320 gam than, 225 - 230 gam axeton cho 1 lt bnh cha). S cu to mt s bnh cha kh v bnh ch kh c th hin trn hnh .

4.4.2 Bnh ch kh : L loi thit b dng iu ch kh axetylen. Bnh ch kh cdng nh hnh 4-8 Bnh ch kh A XTYLEN (Nc SX : Balan) Cc b phn chnh ca bnh ch kh C2H2: 1. Van mt chiu khng cho khng kh i ngc vo bung phn ng. 2. Van bo him (P < 1,5 at) 3. Vt vn 4. Thanh ngang gi np bnh 5. Van x kh 6. Np y 7. ng h o p sut trng bnh 8. Ming ng nc vo bnh 9. Bung cha kh axetylen 10. Kho ng m kh Axetylen 11. Van gim p 12. Np y v mng bo him 13. Kho bo him 14. Van m kh i ra m hn 15. Van kim tra mc nc an ton cho kho bo him lm vic bnh thng 16. Van tho nc 17. ng dn; 18. Mc nc trong bung phn ng; 19. Vch ngn gia 2 bung; 20. Kh k p nc 21. Van kim tra mc nc trong kh p k nc; 22. Np tho nc vi; 23. Mc treo gi cc bua khi khng lm vic 24. Thanh ngang ca gi cc bua can xi CaC2; 25. C di (mc di) ca n by khi h xung; 26. C cu nng h gi ng cc bua can xi 27. n by; 28. Ming ng thi nc; 29. Van kim tra mc nc trong bnh cha kh; 30. Gi cha cc bua can xi (t n); 31. Quai cm ca gi cha cacbua can xi CaC2; 32. Bung phn ng; 33. ng dn kh t bung phn ng ra bung cha; 123

c tnh k thut ca bnh cha : 1. 2. 3. 4. 5. Khi lng cc bua can xi trong mi ln np Kch thc ht cc bua can xi (CaC2) p lc kh Nng sut khi sn xut lin tc Nng sut ln nht : 3 kg : d = 50 - 80 mm : P = 1,5 at : Q = 2000 lt/gi : Q = 2000 lt / gi

4.4.3 Kho bo hima. Hin tng va p ngc hay hin thng chy qut li ca ngn la. Ngn la hn chy n nh s m bo s nung nng v lm nng chy u kim loi, qu trnh vn hnh s an ton. S chy n nh ca ngn la ph thuc vo tc i ra ca hn hp vi tc chy. Nu tc chy ln hn tc i ra ca hn hp (khi p sut trong bnh ch nh hn bn ngoi) th ngn la c th chy qut li vo pha trong m hn n ng dn kh v vo n bnh ch kh; lc c kh nng gy n bnh e do trc tip tnh mng ngi s dng. Hin tng gi l hin tng chy qut li ca ngn la hay hin tng va p ngc. nguyn nhn c th l khi s dng bnh ch kh c th c hin tng p sut trong bnh ch kh gim v c th xy ra trng hp nh hn p sut bn ngoi m hn, hoc do u m hn b nung nng v chy mn rng ra, ... kt qu l p sut gim , tc ra nh hn tc chy. Khi s dng bnh cha kh th p sut trong bnh lun ln hn p sut bn ngoi nn ngn la hn lun nm ngoi m hn nn khng cn s dng kho bo him. Yu cu i vi kho bo him : m bo ngn cn v dp tt hin tng chy qut li ca ngn la, c bn cao chu p sut cao do qu trnh chy, d quan st, d vn hnh bo qun v sa cha, tiu hao t nc,... Kho bo him c nhiu loi h, kn, kh, ... S nguyn l kho bo him kiu kn (xem hnh 4-9, 4-10 ) Khi lm vic bnh thng, kh chy (C2H2) i t bnh ch kh qua van 5 ra m hn. Khi c hin tng va p ngc p sut trong kho bo him tng ln lm ng van 5 li, kh chy khng i vo c; khi p lc do kh chy trong kho bo him cao 6.5 Hn in tip xc 6.5.1. Cu to b mt kim loi hai hay nhiu chi tit lin k li vi nhau th cn p lc ln p cho khong cch gia cac kim loi bng mt thng s mng, c ngha l to nn mi lin kt gia cc nguyn t ca kim loi ny lin kt vi nguyn t ca kim loi kia nh lc ht v lc y gia chng. Song trong thc t iu ny thc hin rt kh v cu to b mt kim loi rt phc tp, g gh, khng phng, thm vo c nhiu cht bn

124

2 1

3

Hnh 5-1 S cu trc b mt kim loi 1. B mt th; 2. B mt t vi (micro); 3. B mt siu nh (Ultramicro)

Lp nguyn t dng t do ch-a cn b ng Lp hi n-c b kim loi ht vo Lp khng kh b kim loi hp Lp oxyd kim loi Lp b kim loi b bin dng Lp kim loi tinh khit (Vng kim loi c bn)

Hnh 5-2 Cu to lp b mt kim loi Qu trnh hnh thnh mi lin k hn khi hn tip xc Hn tip xc l mt trong cc phng php hn p lc. Thc cht qu trnh hn tip xc l mt qu trnh dch chuyn cc phn t kim loi ny tin st vo kim lkoi kia cho n khi khong cch gia chng bng mt thng s mng a = (3 - 5) x 10 -8 cm. Chng ta bit cu trc ca kim loi l cu trc mng tinh th. Kh khong cch gia chng bng mt thng s mng th gia 2 kim loi s xut hin lc tc dng tyng h gia chng to nnb mi lin kt kim loa bn chc. S hnh thnh mi lin kt ny c th m t theo 3 giai on sau: Giai on 1 : Chi tit 1 v chi tit 2 khng hon ton tip xc vi nhau trn ton b b mt m ch xy ra tyi mt s im no . Giai on 2 : Khi c ngun nhit nung nng th cc cht bn b ph hu, ng thi vi lc p tng ln s lm tng tit din tip xc; xut hin nhng ht tinh th chung , hay ni cch khc bt u c nhng mi lin kt kim loi. Giai on 3 : Khi lc p tng t gi tr nht nh th din tch tip xc tng ln gn bng 100 %, khi kim loi t mi lin kt bn chc.125

1

2 P P

Hnh 5-3 a - Giai on 1;

S s hnh thnh mi lin kt khi hn tip xc b. giai on 2; c. Giai on 3 P2 >P1

5.3 c im ca hn in tip xc 1. Hai kim loi lun tip xc nhau nn bo v khng cho khng kh bn ngoi xm nhp vo vng mi hanf, v vy cht lng mi hn cao. 2. in tr tip xc gia kim loi - kim loi, kim loi - in cc nh (khong 0,005 - 0,1 m).

3. Thi gian hn yu cu phi nh (c vi giy) 4. Ngun nhit cung cp cho vng hn c tnh theo cng thc : Q = 0,24 I 2 Rt (cal) I - cng dng in tnh bng A R - in tr vng tip xc (m) t - thi gian hn tnh bng giy 5. in p hn nh Uh = 1 - 5 vn 6. Cng sut ca my hn ln (n 1000 KVA 7. Dng in hn ln c th n 50.000 n 100.000 ampe 8. C th c kh ho v t ng ho qu trnh hn nn nng sut cao 9. Nhc im l my hn phc tp v gi thnh cao 5.4 Phn loi hn tip xc Theo dng mi hn : Hn tip xc im Hn tip xc ng Hn tip xc gip mi Theo ngun in My hn dng xoay chiu My hn dng 1 chiu My hn dng in xung My hn dng tn s cao My hn dng tn s thp Theo in cc My hn 2 in cu My hn nhiu in cc My hn inc cc gi Hn tip xc gip mi

Lc p khi hn

126

P

Lc kp cht P2

Lc kp cht P2P

Hnh 5-4 S nguyn l my hn tip xc gip mi 5.7 Hn tip xc im Khi nim : Hn tip xc im l phng php hn p lc m cc chi tit c hn ni vi nhau theo tng im ring bit. Phn loi : Hn im c th c cc phng php Phn loi : Hn tip xc dim 1 pha; hn tip xc im 2 pha v hn tip xc im bng in cc gi. S nguyn l hn tip xc im

a.

b.

c.

Hnh 5-8 S nguyn l cc phng php hn im127

a - S hn im 2 pha b - S hn im 1 pha c - S hn im bng in cc gi; 5.8 Hn ng :

5.8.1 Khi nim : L mt phng php hn tip xc tng t hn im nhng ccim hn c ni lin nhau to thnh ng hn nn gi l hn ng. Khi hn ng , in cc hn uc thay th bng bnh xe in cc v ln theo ng hn. 5.8.2 Phm vi ng dng hn cc chi tit mng, cc kt cu trong cng ngh ch to t, thng du, ... t cc loi vt liu khc nhau nh thp, ng nhm, manh, ... 5.8.3 S nguyn l my hn ng

3

1

2Hnh 5-12 S nguyn l my hn ng 1 - Ngun in hn 2 - H thng iu khin chu k hn 3 - Cng tc t; 4 - Cc phch cm thay i in p cung s cp; 5 - My bin p hn 6 - Khung ngoi ca my hn ng bao gm : cun th cp, dy dn in vt hn, c cu kp chi tit, bnh in cc hn.

128

Hnh 4-7 S cu to mt s bnh cha kh

a. Bnh cha kh xy; b. Bnh cha kh axetylen (C2H2); b. Bnh cha kh prpan (C3H8)

129

Hnh 4-8 S nguyn l bnh ch kh axtylen

th mng 8 s b thng to iuC2H2 cho kh chy thot ra ngoi (xem hnh 4-7, 4kin 9).C2H2 Ngn la chy qut li 130

Hnh 4-9 S nguyn l cc loi kho bo him kiu t.

C2H

C2H2

Hnh 4-10 S nguyn l cc loi kho bo him kiu kh

4.4.3 Van gim p Cng dng ca van gim p Van gim p c cng dng gim p sut t bnh cha xung p sut khi lm vic v lm n nh p sut trong sut thi gian lm vic. Phn loi van gim p : van gim p xy, van gim p axetylen, ... Theo nguyn l tc dung : c van giam p tc dng nghch v tc dng thun; Theo s bung c loi 1 bung, 2 bung v nhiu bung,... S nguyn l van gim p kiu nghch

2 1Kh ra t bnh

3 4 5 6

Kh ra m h

131

Hnh 4-11 S nguyn l van gim p kiu nghch 1 - ng h o p sut trong bnh cha 2 - ng h o p sut ra m hn, 3 - l xo gi np van 4 - Mng n hi 5 - l xo iu chnh mng n hi 6 - Vt iu chnh v tr mng ng hi

S nguyn l van gim p kiu thun (chiu ra ca kh cng chiu vi chiu m van)Kh ra t bnh cha Kh ra m hn

Hnh 4-12 S nguyn l van gim p kiu thun

Bnh ch kh :L loi thit b dng iu ch kh axetylen. Bnh ch kh c dng nh hnh 4-8 Bnh ch kh A XTYLEN (Nc SX : Balan) Cc b phn chnh ca bnh ch kh C2H2: 1. Van mt chiu khng cho khng kh i ngc vo bung phn ng. 2. Van bo him (P < 1,5 at) 3. Vt vn 4. Thanh ngang gi np bnh 5. Van x kh 6. Np y 7. ng h o p sut trng bnh 8. Ming ng nc vo bnh 9. Bung cha kh axetylen 10. Kho ng m kh Axetylen 11. Van gim p 12. Np y v mng bo him 13. Kho bo him 14. Van m kh i ra m hn 15. Van kim tra mc nc an ton cho kho bo him lm vic bnh thng 16. Van tho nc 17. ng dn; 18. Mc nc trong bung phn ng; 19. Vch ngn gia 2 bung; 20. Kh k p nc 21. Van kim tra mc nc trong kh p k nc; 132

22. Np tho nc vi; 23. Mc treo gi cc bua khi khng lm vic 24. Thanh ngang ca gi cc bua can xi CaC2; 25. C di (mc di) ca n by khi h xung; 26. C cu nng h gi ng cc bua can xi 27. n by; 28. Ming ng thi nc; 29. Van kim tra mc nc trong bnh cha kh; 30. Gi cha cc bua can xi (t n); 31. Quai cm ca gi cha cacbua can xi CaC2; 32. Bung phn ng; 33. ng dn kh t bung phn ng ra bung cha; c tnh k thut ca bnh cha : 6. Khi lng cc bua can xi trong mi ln np 7. Kch thc ht cc bua can xi (CaC2) 8. p lc kh 9. Nng sut khi sn xut lin tc 10. Nng sut ln nht : 3 kg : d = 50 - 80 mm : P = 1,5 at : Q = 2000 lt/gi : Q = 2000 lt / gi

133

IV Ti liu tham kho : 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Nguyn B An, S tay th hn, NXB xy dng, HfnI, 1986 inh Minh Dim, Conga ngh kim loI tp 3 (Phn Hn v ct kim loI) HN, 2001 L Conga Dng, Vt liu hc, NXB KH&KT, H NI, 2000. Nghim Hng, Sch tra cu thp gang thng dng,Trng HBK H NI, 1997 L Nhng, K thut dp nguI, NXB CNKT, H NI, 1981 L Nhng, Rn v dp nng, NXB CNKT, H NI, 1978. Trn Hu Tng, inh Cng M, Trn TI, Nguyn Vn Sim, L Vit Ngu, V Conga Lun, Conga Ngh kim loI tp 2, NXB H&THCN, 1972 Tn Yn, Conga Ngh dp nguI, NXB KHKT, H NI, 1974. .. 4 - . - . 1971 . . . . 1974 - . - . 1975

12. .. x - - - 1981 13. . x - . - . 1974. 14. .. x - . . 1975 15. .. - . - . 1977

Mc lc

ChngChng 1

Ni dungVt liu kim loi

1.1 Tnh cht ca kim loi 1.2 Phn loi vt liu kim loi n cht 1.3 Kim loi mu 1.4 C tnh ca kim loi 1.5 Gang v cc ng dng ca n 1.6 Thp v cc ng dng ca n 1.7 Thp hp kim 1.8 Hp kim cng 1.9 Cc loi thp khcChng 2 Thp bn nhit v chu nhit

Trang 1 1 1 2 3 6 10 13 15 17 20 19 19 19 21 25 26 35 35 36 36 37 40 40 45 45 47 52 53 56 58 62

2.1 Khi nim chung v thp chu nhit bn nhit 2.2 Yu cu i vi chi tit khi lm vic nhit cao 2.3 Qu trnh xy ho thp 2.4 S ph hu nhit cao 2.5 Cc phng php ho bn nhit cao 2.6 Thp chu nhit bn nhit Chng 3Cc phng php nhit luyn

3.1Khi nim chung v nhit luyn 3.2 iu kin nhit luyn 3.3 Gin trng thi st cc bon (Fe-C) 3.4 Cc phng php nhit luyn 3.5 S tng hp qu trnh nhit luyn 3.6 Ho nhit luyn. Chng 4c kim loi

4.1 Thc cht c im v cng dng c kim loi 4.2 Cc b phn chnh ca mt khun c 4.3 Hn hp lm khun li 4.4 Ch to b mu v hp li 4.5 Tnh c ca hp kim 4.6 c gang xm 4.7 Cc phng php c c bit

138

Chng 5

Gia cng kim loi bng p lc

5.1 Khi nim chung v gia cng p lc 5.2 Khi nim v bin dng deo kim loi 5.3 Cc hin tng xy ra khi bin dng do 5.4 Mt s nh lut p dng trong gia cng p lc 5.5 Nung nng kim loi khi gia cng p lc 5.6 Cn kim loi 5.7 K o kim loi 5.8 p kim loi 5.9 Rn t do 5.10 Dp th tch 5.11 Dp tmChng 6 Hn v ct kim loi

68 68 69 70 71 73 78 82 84 85 90 92 98 98 99 101 119 133 137 138

6.1 Khi nim chung 6.2 T chc kim loi mi hn v vng cn n 6.3 Hn h quang 6.4 Hn v ct kim loi bng kh 6.5 Hn tip xc Ti liu tham kho Mc lc

139