CC DNG KHUYT TT MI HN Nhng sai lch v hnh dng, kch thc v t chc
kim loi ca kt cu hn so vi tiu chun thit k v yu cu k thut, lm gim bn
v kh nng lm vic ca n, c gi l nhng khuyt tt hn. 1. NT NT - L mt
trong nhng khuyt tt nghim trng nht ca lin kt hn, nt c th xut hin
trn b mt mi hn, trong mi hn v vng nh hng nhit. Vt nt c th xut hin
cc nhit khc nhau Nt nng: Xut hin trong qu trnh kt tinh ca lin kt hn
khi nhit cn kh cao, trn 10000C. Nt ngui: Xut hin sau khi kt thc qu
trnh hn v nhit di 10000C, nt ngui c th xut hin sau vi gi hoc sau vi
ngy. Vt nt c cc kch thc khc nhau, c th l nt t vi hay nt th i. Cc vt
nt th c th gy ph hu kt cu ngay khi lm vic. Cc vt nt t vi, trong qu
trnh lm vic ca kt cu s pht trin rng dn ra to thnh c vt nt th i
C th pht hin cc vt nt bng mt thng hoc vi knh lp i vi cc vt nt th
di v nm b mt ca lin kt hn. i vi cc vt nt t vi v nm bn trong mi hn
ch c th pht hin c khi dng cc phng php kim tra nh siu m, kim tra t
tnh, chp X quang, v.v NGUYN NHN V BIN PHP KHC PHC
2. R KH
R KH - sinh ra do hin tng kh trong kim loi mi hn khng kp thot ra
ngoi khi kim loi mi hn ng c. R kh c th sinh ra bn trong hoc trn b
mt mi hn, c th tp trung hoc nm ri rc trong mi hn.
S tn ti ca r kh trong mi hn s lm gim tit din lm vic, gim cng chu
lc v kn ca lin kt hn. NGUYN NHN Hm lng cc bon trong kim loi c bn
hoc trong vt hn qu cao.
Vt liu hn b m, b mt chi tit hn khi hn b bn, dnh du m, g, hi nc
Chiu di h quang ln, tc hn qu cao BIN PHP KHC PHC Dng vt liu hn c hm
lng cc bon thp Trc khi hn vt liu hn phi c sy kh, b mt phi c lm sch.
Gi chiu di ct h quang ngn, gim tc hn. Sau khi hn khng g x hn ngay,
ko di thi gian gi nhit cho mi hn Ring i vi hn c kh bo v (MIG/MAG) S
dng kh bo v ph hp, c tinh khit cao, lu lng kh cp cho mi hn khi hn
phi 3. LN X LN X - l loi khuyt tt rt d xut hin trong mi hn, x hn v
tp cht phi kim loi c th tn ti trong mi hn, cng c th trn b mt mi hn
hoc chn mi hn
Mi hn b ln x hn s c nh hng ln n dai va p v tnh do ca kim loi mi
hn, lm gim kh nng lm vic ca lin kt hn di tc dng ca ti trng ng.
NGUYN NHN Dng in hn qu nh, khng nhit lng cung cp cho kim loi nng
chy v x kh thot ra khi vng hn. Mp hn cha c lm sch hoc khi hn nh hay
hn nhiu lp cha g sch x. Gc hn cha hp l v tc hn qu cao. Tc lm ngui
qu nhanh, x khng kp thot ra ngoi. BIN PHP KHC PHC Tng dng in hn cho
thch hp, hn bng h quang ngn v tng thi gian dng li ca h quang Lm sch
vt hn trc khi hn, g sch x mi hn nh v cc lp hn. Thay i gc v phng php
di chuyn que hn cho hp l, gim tc hn trnh x trn ln vo trong vng hn
hoc chy v pha trc vng hn.
4. KHNG NGU HN KHNG NGU - l khuyt tt nghim trng trong lin kt hn,
n c th dn n nt. Hn khng ngu sinh ra gc mi hn, mp hn hoc gia cc lp
hn. Phn ln kt cu b ph hu u do hn khng ngu.
NGUYN NHN Mp hn chun b cha hp l, gc vt qu nh Dng in hn qu nh hoc
tc hn qu nhanh Gc que hn cha hp l v cch a in cc khng hp l. Chiu di
ct h quang qu ln BIN PHP KHC PHC Lm sch lin kt trc khi hn, tng gc
vt v khe h hn Tng dng in hn v gim tc hn 5. CHY CHN CHY CHN - l phn
b lm thnh rnh dc theo ranh gii gia kim loi c bn v kim loi p. Bao gm
c chn mi hn mt trc v chn mi hn ngu. Chy chn lm gim tit din ca lin
kt hn, to s tp chung ng sut cao v dn n s ph hu ca kt cu trong qu
trnh s dng.
NGUYN NHN Dng in hn qu ln Chiu di ct h quang qu ln Gc que hn v
cch a que hn cha hp l S dng cha ng kch thc in cc hn
BIN PHP KHC PHC Khi dao ng m sang hai bn mi hn c thi gian dng
cho kim loi ph in y vo hai bn. m bo ng gc chuyn ng ca que hn iu
chnh li ch dng in, in p. iu chnh li khong cch ct h quang, t u m
xung ti vt hn l 10 - 15mm. iu chnh li vn tc hn, v gc m cho ph hp Hn
ch s thi tt h quang bng cch che chn gi. iu chnh li khong cch ct h
quang cho thch hp 6. HIN TNG BN TO Khuyt tt ny l hin tng bn to kim
loi ln vt hn, do vt hn khng m bo cht lng, thiu kh bo v hoc s dng
khng ng loi kh, gy mt thm m lin kt hn. NGUYN NHN Chiu di ct h quang
qu cao B mt mi hn b bn hoc du m. Tc ra dy ln qu chy khng ht H quang
b thi tt Gc m hn nghing qu. BIN PHP KHC PHC iu chnh li khong cch ct
h quang cho thch hp V sinh b mt mi hn cho sch s trc khi hn iu chnh
li ch ra dy ph hp vi in p h quang Che chn gi khng c hin tng gi thi
lch h quang Chnh li gc m hn cho ph hp, thng t 90 - 105 so vi hng hn
v vung gc vi hai bn.7. BIN DNG
Bin dng hn l nhng khuyt tt lm sai lch hnh dng mt ngoi ca lin kt
hn, lm n khng tho mn vi cc yu cu k thut v thit k. Chiu cao phn nh
hoc chiu rng ca mi hn khng ng u. ng hn vn vo khng phng
B mt mi hn nhp nh NGUYN NHN G lp v chun b mp hn cha hp l Trnh t
hn khng ng Vt liu hn khng m bo cht lng Tc hn v dng in hn ln. BIN
PHP KHC PHC p dng quy trnh hn th t ph hp Hn g tng phn v vng chng s
bin dng Vt mp hn ng gc v g mu hn theo ng yu cu iu chnh li ch dng
in, in p.
CC PHNG PHP KIM TRA MI HNMc ch ca phng php kim tra cht lng lin
kt hn l xc nh kh nng p ng cc iu kin lm vic ca lin kt hn, c th xc nh
cc tnh cht c hc, ho hc, kim loi hc v xc nh cc khuyt tt. Ngoi ra vic
kim tra cht lng mi hn cn c dng phn loi cc quy trnh hn v trnh tay
ngh th hn. Cc phng php kim tra c chia thnh hai phng php chnh :- Kim
tra ph hy - Kim tra khng ph hy
1. KIM TRA BNG PHNG PHP PH HU1.1 KIM TRA C TNH CA MI HN
Mc ch ca vic kim tra ny l xc nh c tnh c hc ca lin kt hn so snh
vi c tnh ca kim loi c bn. Qua , cng c c s nh gi trnh tay ngh ca ngi
th hn mt cch chnh xc hn. Cn c vo yu cu k thut, kh nng thit b kim
tra, quy trnh hn c p dng, m tin hnh th ko, th un, th cng v dai va p
ca lin kt di tc dng ca ti trng tnh hoc ti trng ng.
Cc phng php kim tra: Kim tra th ko Kim tra th un Kim tra dai va
p th ko, th un hoc cc phng php th dai va p cc mu c ct ra t phn kim
loi p ca lin kt hn v c gia cng c kh t c hnh dng v kch thc theo cc
tiu chun c p dng1.2 KIM TRA CU TRC CA LIN KT HN
Gm c hai dng l: Kim tra th v kim tra t vi KIM TRA TH - c tin hnh
trc tip vi cc mu th kim loi hoc cc mt gy ca chng. Cc mu th c ct ra
t lin kt hn, mi bng v ty sch bng dung dch axit nitric 25% ri dng
knh lp hoc mt thng pht hin khuyt tt ca lin kt hn, c th khoan ly mu
ngay trn kim loi p nghin cu. Thng dng cc mi khoan c ng knh rng hn
chiu rng ca mi hn 3mm ly c phn kim loi c bn v kim loi mi hn. KIM
TRA CU TRC T VI - c tin hnh di loi knh lp c phng i ln (100-500 ln),
nh vy c th xc nh c d dng v chnh xc cht lng kim loi ca lin kt hn.2.
KIM TRA BNG PHNG PHP KHNG PH HUPhng php kim tra ny c thc hin trc
tip vi lin kt hn v trn sn phm hn c th m khng gy nn bin i c tnh ca
sn phm. 2.1 KIM TRA BNG MT THNG
y l phng php c s dng thng dng kim tra ton b qu trnh hn, c th l
kim tra trc khi hn, trong khi v sau khi hn. Phng php ny d thc hin,
c th gip trnh c cc khuyt tt hoc pht hin sm cc khuyt tt trong khi
hn. Kim tra trc khi hn Kim tra bn v, cc tiu chun t ra cho lin kt
hn
Kim tra chng ch vt liu c s dng c v ph hp vi yu cu khng Kim tra
gia cng g lp, khe h v mp vt c ng vi thit k khng Kim tra sch ca lin
kt hn Kim tra trong khi hn Kim tra cc thng s ca quy trnh hn. Loi vt
liu hn tiu hao. Nhit nung nng trc khi hn (nu c yu cu) V tr hn v cht
lng b mt vt hn Trnh t hn X l cc mi hn nh v v sinh gia cc lp hn. Kch
thc lin kt hn Nhit v thi gian s l nhit sau khi hn. Kim tra sau khi
hn Lm sch b mt lin kt hn (b mt mi hn v vng kim loi c bn) Quan st k
bng mt thng hoc bng knh lp Kim tra kch thc ca mi hn so vi bn v thit
k. 2.2 KIM TRA BNG DUNG DCH CH TH MU y l phng php s dng cc dung dch
thm thu vo cc vt nt, r kh nh ca lin kt hn m khng th quan st c bng
mt thng, sau dng cc cht hin th mu pht hin ra v tr m dungdch thm thu
cn nm li cc vt nt cng nh r kh. Cn lu l : Phng php ny ch pht hin c
cc khuyt tt m ra trn b mt vt liu cn kim tra. Thng thng s dng 3 loi
dung dch v c tin hnh theo cc bc sau: Dng dung dch lm sch ty sch b
mt mi hn Phun dung dch thm thu ln b mt mi hn
Sau khi thi gian dung dch thm thu vo cc vt nt, r kh, th lau sch
b mt mi hn. Dng dung dch hin th mu phun ln vng mi hn va thc hin cc
bc trn pht hin khuyt tt. Phng php ny c tnh u vit l n gin, d thc
hin, pht hin c c cc khuyt tt nh khng quan st c bng mt thng mt cch
nhanh chng, tuy nhin n khng pht hin c nhng khuyt tt nm bn trong ca
lin kt hn v chiu su ca khuyt tt
2.3 KIM TRA BNG T TNH Dng bt st t rc trong trng ca nam chm t
nhin hay in t th n s phn b theo quy lut ca cc ng sc t. Quy lut ny
trc tin ph thuc vo s ng nht ca cu trc st t, nu nh trn ng i cc ng sc
t gp phi cc vt nt, khe h th quy lut phn b ca cc ng sc t thay i so
vi nhng khu vc khc do c s khc nhau v thm t. Khi gp cc khuyt tt cc
ng sc t tn ra bao xung quanh ly cc khuyt tt . Da vo nguyn l ngi ta
tin hnh kim tra bng cch rc bt st ln b mt mi hn, sau t kt cu hn vo
trong mt t trng ri nhn vo s phn b cc ng sc t c th pht hin v phn bit
c khuyt tt. Phng php ny ch p dng i vi cc vt liu t tinh, n cho php
pht hin cc khuyt tt nt b mt c kch thc rt nh, cc khuyt tt pha di b
mt lin kt hn nh: Nt vng nh hng nhit Hn khng ngu Nt pha di b mt R
kh, ln x 2.4 KIM TRA BNG TIA PHNG X (RNGHEN V GAMMA) Tia X v tia
Gamma l sng in t c bc sng rt ngn, tn s dao ng v nng lng rt cao c th
i xuyn qua khi kim loi dy. Mt phn bc x tia X v tia gamma b hp th,
mt phn s i qua mu kim \tra, lng hp th v lng i qua c xc nh theo chiu
dy ca mu. Khi c khuyt tt bn trong, chiu dy hp thc bc x s gim, iu ny
to phn khc bit trong phn hp th, c ghi li trn phim dng hnh nh bng gi
l nh bc x. Gii on phim s cho php pht hin cc khuyt tt bn trong vt hn
mt cch chnh xc. Phng php ny cho php pht hin c tt c cc loi khuyt tt
tr cc vt nt vi nh. 2.5 KIM TRA BNG SIU M
Sng siu m l dng sng m thanh dao ng n hi trong mi trng vt cht nht
nh, khi truyn qua bin gii gia cc mi trng vt cht khc nhau sng siu m
s b khc x hay phn tr li. Da vo c tnh , ngi ta ch to c cc loi my d
siu m pht hin cc khuyt tt nm su trong lng kim loi. Phng php ny cho
php pht hin cc vt nt, hn khng ngu, r kh, kt x,v c nhng thay i rt nh
vng nh hng nhit ca lin kt hn. Quan st trn mn nh ca my bng nhng xung
hin th, c th cho php bit c chnh xc v tr ca cc khuyt tt. 2.6 PHNG
PHP KIM TRA KN CA LIN KT HN Kim tra kn bng p lc kh Trc lc kim tra
cn bt kn, sau bm kh vo (khng kh hoc kh tr) n mt p sut nht nh no ,
sau bi nc x phng ln mt ngoi mi hn v quan st (100 gam x phng trn mt
lt nc).Nhng ch b r r s c pht hin theo cc v tr m bong bng x phng ni
ln. Kim tra bng p lc nc kim tra ngi ta bm nc vo kt cu cn kim tra,
to mt p sut d cao hn p sut lm vic 1,5 n 2 ln v gi p sut trong vng 5
- 6 pht. Giai on tip theo l h p xung n p sut lm vic ri dng ba g nh
vng xung quanh mi hn (rng 15 - 20mm)v quan st xem nc c r r ra khng.
i vi nhng kt cu h nh bn cha, thng,ch cn th bng cch bm nc vo v gi
trong vng 2 - 24 gi v quan st xem nc c b r r ra khng. Kim tra bng
phng php to chn khng Ch p dng trong iu kin khng tin hnh c bng cc
phng php th kn trn (v d nh: y bn, b) Trc tin bi nc x phng ln mi hn
cn kim tra. t bung chn khng trc tip ln vng mi hn cn kim tra, ti cc
vin xung quanh bung chn khng c rong cao su to kn cn thit vi vt liu
kim tra, chn khng c to ra nh c bm chn khng t pha ngoi. Do c s chnh
lch ln v p sut, khng kh s chui vo bung chn khng qua cc khuyt tt, np
y c thit k trong sut qua ta c th quan st v tr cc khuyt tt theo cc
bong bng x phng. LEVEL OF WELDING WORKERCng nhn hn in Bc 1 a) Hiu
bit: 1. Bit c bn v chi tit n gin qua 2 hnh chiu, cc k hiu mi hn ni.
2. Hiu c khi nim v dung sai kch thc. 3. Bit tnh cht ca vt liu thng
dng lm t thp cc bon.
4. Nm c kin thc thng thng v in v c c ch s trn cc ng h ca my hn
mt chiu, my hn xoay chiu. 5. Phn bit uc mi hn ngu hay khng ngu, tt
hay xu. 6. Bit tn v cng dng ca cc loi dng c chnh dng trong ngh v
dng c phng h c nhn. 7. Bit tnh cht nguy him ca dng in v bin php
phng nga tai nn. b) Lm c: 1. u c dy nng v dy ngui ca my hn. 2. Hn
nh, g c cc kt cu khng quan trng, hn ni uc tn dy t 5 mm tr ln. 3. Hn
c cc mi hn thng gc ca cc kt cu cong giang khng quan trng trong cng
ngh ng tu c trng ti 300 tn v tr hn bng. 4. Ty sch c cc mi hn thng
thng. 5. u c in ngun cho my hn xoay chiu. Bc 2 a) Hiu bit: 1. Hiu c
dung sai lp ghp, tra c dung sai kch thc. 2. Bit tiu chun, hnh dng,
cch gi tn cc loi thp nh hnh thng dng trong cng ngh ng tu. 3. Nm c
tnh cht, cng dng ca cc kim loi thng thng v vt liu thng dng trong
cng ngh ng tu. 4. c c cc k hiu mi hn theo tiu chun Nh nc. 5. Bit tn
gi, thnh phn, tnh cht, cng dng ca cc loi que hn thng gp, bit s lc v
thnh phn lp thuc bc que hn. 6. Bit nguyn nhn gy ra khuyt tt bn ngoi
ca mi hn v cch khc phc. 7. Bit cc phng php chuyn ng ca u que hn
trong hn tay. 8. Bit s lc nguyn l, cu to my hn xoay chiu, my hn mt
chiu thng dng. 9. Bit bin php phng nga tai nn in git v cch cp cu
khi b in git. b) Lm c: 1. iu chnh c dng in hn cho ph hp vi ng knh
que hn, chiu dy vt hn. 2. Hn c t th hn bng cc mi hn ni tip thng gc
loi tn 5 - 8 mm vi vt hn khng quan trng. 3. Hn c cc mi hn li, lm,
hn chng mi cc tm thp dy 5 -10 mm t th hn bng. 4. Pht hin c mt s h
hng thng thng ca my hn gi th in n sa cha. Bc 3 a) Hiu bit: 1. c c
bn v ca vt th qua 3 hnh chiu. 2. Bit tnh, ly du cc loi st, thp nh
hnh v tn tm trc khi un v hn. 3. Bit thnh phn chnh v tc dng ca cc
cht bo v mi hn. 4. Bit c cc khuyt tt ca mi hn trong cng ngh hn tay
v phng php trnh. 5. Nm c s lc cc phng php chng bin dng khi hn. 6.
Bit xc nh ng knh que hn theo loi mi hn v chiu dy tn. 7. Hiu c nguyn
l, cu to ca cc my hn thng dng v cc h hng thng gp. 8. Bit chn tit
din dy hn theo dng in hn.
9. Hiu c nguyn l, cu to dng c o in nh: vn k, ampe k. 10. Bit s
lc nguyn l hn t ng v bn t ng. b) Lm c: 1. Hn c cc b my vi chiu dy
tn n 12 mm v tr hn bng. 2. Hn ni kn nc c cc loi ng vi nhau, ng vi
mt bch ca kt cu chu p lc thp. 3. Hn p c cc chi tit khng quan trng
bng thp cc bon thp. 4. Hn p c t th hn ngang, hn leo cc b phn khng
quan trng nh: vch thng cha nc, cha du, vch tu, vch x lan. 5. Hn p v
lng c mt phng rng n 20 cm2. 6. Ct c tn dy 2 - 4 mm m bo k thut. 7.
S dng c my hn chm. 8. Lm c mt s vic ca th st bc 1 c lin quan. Bc 4
a) Hiu bit: 1. c c bn v kt cu hn v bn v c mt ct ngang. 2. Nm vng cu
to, nguyn l ca my pht in hn 1 chiu. 3. Bit phng php hn nng, hn lnh
gang v cch b tr mp hn. 4. Nm c mt s iu cn thit khi hn thp khng g.
5. Bit phn tch c nguyn nhn bin dng khi hn v cch chng bin dng. 6.
Bit cc phng php nghim thu vt hn bng cch kim tra bn ngoi, o kch thc,
th kn. 7. Nm c nguyn tc hn t ng, hn bn t ng: hn di lp thuc v hn
trong kh bo v. b) Lm c: 1. Hn c cc t th (hn leo, ngang, trn) cc chi
tit quan trng nh: ni cc phn on, tng on tu, hn cc ng di mn nc ca tu,
s lan. 2. Hn p c trc li, trc chn vt, trc trung gian, bnh rng hp s.
3. Hn c cc t th mi hn tn mng n 2 mm. 4. Hn c cc thng, ng t thp cc
bon chu p sut n 20 kg/cm2 v chu nhit n 300 oC. 5. Chun b hn v hn c
cc chi tit bng gang theo phng php hn lnh. 6. Pht hin c cc h hng
thng thng ca my hn v t sa cha c mt s trng hp. Bc 5 a) Hiu bit: 1.
Bit tnh cht, thnh phn, tc dng ca mt s kim loi mu v hp kim ca chng.
2. c c bn v kt cu hn tng i phc tp vi nhiu chi tit. 3. Bit nguyn nhn
gy ra cc ng sut v nhit, bin dng, cc phng php gim ng sut, bin dng
khi hn. 4. Bit ni v vn hnh cc my pht in v bin th hn lm vic song
song, bit dng cc my hn cng sut thp hn cc chi tit dy, m mp rng. 5.
Bit phng php nhit luyn sau khi hn. 6. Bit kt cu, cng dng ca bnh
sinh kh axtylen v xy. 7. Lp c trnh t hn cho th bc di. b) Lm c: 1.
Hn c bnh, ng chu p lc n 50 kg/cm2, lm vic nhit n 300 - 400 oC, chu
c
chn ng. 2. Hn c b my tu bin ln. 3. Hn c cc ng nc bng gang, cc v
hp s, v my bo m yu cu k thut v m thut. 4. Hn c t th hn trn mt s chi
tit, kt cu quan trng nh: ni tng on ca tu, tn v sng mi, sng li tu v
s lan. 5. Hn c cc kim loi mu nh: ng , ng thanh, ng thau. 6. Hn c hp
my v cc kt cu i hi chnh xc cao, m bo khng bin dng qu gii hn v ng
sut d ln. 7. X l c mt s bin dng sau khi hn. 8. Lm c th st c tay ngh
tng ng bc 2. 9. S dng c cc thit b hn hi v bin php an ton th hn hi
bc 2. Bc 6 a) Hiu bit: 1. Phc ho c g dng trong cng ngh hn. 2. Bit s
dng cc bin php cn thit trc khi hn gim ti a bin dng v ng sut sau khi
hn. 3. Bit phng php x l nhit trc khi hn. 4. Bit cu to, nguyn l lm
vic ca thit b hn t ng, hn bn t ng, hn bm, hn i u. 5. Bit cc phng
php c bn kim tra cht lng mi hn. 6. Bit trnh t, cng ngh hn cc mi hn
vt mp kiu X n 12 lp v quy cch que hn i vi mi lp hn. 7. Bit t chc ni
lm vic an ton v khoa hc. 8. C hiu bit v hn hi nh th hn hi bc 3. b)
Lm c: 1. S dng c my hn bn t ng, hn chm, hn i u. 2. Hn c ni hi, cc
kt cu chu p lc n 60 kg/cm2, chu nhit n 400 oC. 3. Hn c mi hn trn ca
tn mng 1,5 mm m bo yu cu k thut v m thut trn sut chiu di mi hn. 4.
Hn c tn dy 20 mm, hn ni cc loi trc ln ng knh n 100 mm m bo yu cu k
thut, khng bin dng qu tiu chun cho php. 5. Hn c thp khng g m bo yu
cu k thut. 6. Sa cha uc cc khuyt tt mi hn. 7. Lm c th hn hi c tay
ngh tng ng bc 3 v lm c mt s vic lin quan ca th st bc 3. 8. Tng hp v
ph bin kinh nghim sn xut tin tin, c nng sut v cht lng cao. Bc 7 a)
Hiu bit: 1. Hiu bit c k thut in trnh s cp. 2. Bit hu ht cc phng php
kim tra cht lng mi hn. 3. Bit v bin i cht kim loi trong mi hn v
nguyn nhn gy cht lng xu. 4. Nm c cu to, nguyn l lm vic ca thit b
kim tra mi hn bng siu m. 5. Nm c tnh nng k thut ca tt c cc thit b
hn hin c.
6. Bit phng php pha ch thuc hn dng cho hn bn t ng, hn t ng v bit
cc loi kh thng dng bo v mi hn trong hn bn t ng. 7. Bit tnh cng mi
hn. 8. Hiu bit c cc kiu g hn tin tin v bit lp trnh t mi hn trong mt
kt cu nhm gim bin dng hn v ng sut sau hn. 9. C hiu bit v hn hi nh
th hn hi bc 4. 10. Nm c l thuyt g, rn tng ng th bc 3. b) Lm c: 1.
Hn c mi chi tit, kt cu phc tp, mi t th phi qua trong cng ngh hn in.
2. S dng c cc thit b kim tra cht lng mi hn khi c ti liu hng dn. 3.
Pht hin, sa cha c cc h hng ca my hn tay v my hn bn t ng. 4. Lm c mt
s cng vic ca th st bc 4 v th hn hi bc 4. 5. Gii quyt c tt c cc kh
khn v k thut hn in. 6. Lp c quy trnh hn cho cng vic bc th ca mnh v
bc di, pht hin sai st trong cc quy trnh. 7. Tng kt c kinh nghim
trong ngh v xut cc ci tin, sng kin nhm tit kim vt t, nng cao nng
sut lao ng v cht lng sn phm.
