Bi tp ln
Mn: Cng ngh kim loi
MC LC 1. V bn v chi tit ca ming lt ray tu 2. Phn tch kt cu thnh lp bn v vt c. 3. V bn v mu v hp li. 4. Quy trnh lm khun c. 5. Tnh ton thit k h thng rt v tnh lc khun.
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
A- THUYT MINH 1/ phn tch bn v chi tit bn v chi tit ca ming lt ray tu
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
- Phn tch kt cu, thnh lp bn v c ming lt ray tu phn tch k cu, tnh ton cc thng s cho bn v vt ming lt ray tu Da vo bn v chi tit ta thnh lp bn v chi tit ca ming lt ray tu Ming lt ray tu l mt chi tit st ng ray tu c nh li, v ming lt ray tu cng phi chu mt lc ln khi tu chy qua ,Xut pht t iu kin lm vic nh vy nn vt liu chn c ming lt ray tu bng thp. u im ca thp l c tnh c tt, ct gt d dng nh cng khng cao, phoi d gy. Sau khi c xong chuyn sang gia cng li cc b mt ca ming lt ray tu nh yu cu ghi trn bn v chi tit bng my tin. Kch thc vt c = kch thc chi tit + dung sai c + lng d gia cng c. Dung sai c da vo bng 4.2 sch dung sai lp ghp ca NINH C TN ta tra c cc tr s dung sai ca kch thc danh ngha c trn bn v chi tit ming lt ray tu
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
2.Bn v vt cGVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
2.chn mt phn khun ,Bn v c v trn c s bn v chi tit, n th hin c mt phn khun, lng d gia cng, dc bn hnh gc lng , li, gi li, khe h gi li, cc kich thc t mt chun 3.xc nh lng d gia cng 4.xc nh dung sai vt c .(hnh v) 5.xc nh bn knh gc ln . m bo bn cho khun mu, ch tip gipa
Gc trong : r = 3 + 5
1
1 a +b 2
R
r
Gc ngoi : R = r + b a,b l chiu dy thnh vt c giao nhau. 6.xc nh dc rt mu.H3.Gc c
. dc : m bo rt khun mu, nhng nu dc qu ln s gy ra sai lch nn ta phi chn va , do mt khng gia cng c v cn c vo chiu dy thnh vt c ta chn dc m nghing 1 7 li vt c 8. tai gi mu . khi nim - B mu: L cng c chnh to hnh khun c. B mu bao gm: Mu chnh, tm mu, mu ca h thng rt, u hi, u ngt. - Hp li: Dng ch to ra li. Li to hnh dng bn trong ca vt c.GVHD: NGUYN B THUN SVTH: L QUANG PHONG
b
Bi tp ln
Mn: Cng ngh kim loi
9. cc yu cu thit k mu ming lt ray tu - Cu to phi n gin, d ch to mu v hp li. - bn t ming ri nh. - B mu dng c lu t, b bin dng. - chnh xc, nhn bng. 10. Thit k mu ming lt ray tu - Vt liu lm mu l g - Mt phn mu trng vi mt phn khun - Kch thc mu = kch thc vt c + co kim loi - Vt liu c ming lt ray tu l thp do co l 2%
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
3.B tr vt c trong khun
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
4. BN V VT MU
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
bn v hp li
_ Vt liu lm hp li l g v g c u im l r, nh, d gia cng. Do yu cu ng knh ca li khng ln nn vt liu lm hp li c th chn bng g tp h gi thnh sn phm m yu cu k thut vn t.
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
a5: xc nh kch thc ng rt Bc 1: Lm na khung di t tm mu sau t na mu di ln tm mu ri t mu rc lp phn chi ln mu tip tho rc lp ct o ln mu, ct m vo dm cht ln 1. Tip tc ct o vo dm cht ln 2, gt phng v xm hi. Bc 2: Lm na khun trn. quay na khun di 1800 t na khun trn ln nh v vi khun di bng cc cht nh v. Lp na mu trn vo khun di bng cc cht nh v rc mt lp phn ch. th ng rt, u hi, u ngt. Tip theo rc lp ct o vo v lam tng t nh lm na khun di sau xm hi. Bc 3: Tho lp khun. Theo cht nh v nhc khun trn ra tin hnh rt mu chnh v rt mu ca h thng rt, hi u ngt, s cha lng khung v khot rnh lc x v rnh dn, sn khun tin hnh lp rp khun.
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
11.Tnh ton h thng rt. a.xc nh din tch rnh dn ,ng rt,rnh lc x. Thit k h thng rt H thng rt l h thng dn kim loi lng t thng rt vo khun. S b tr ca h thng rt quyt nh cht lng vt c v gim c hao ph kim loi vo h thng rt. Hao ph do h thng rt gy nn t n 30%. Yu cu : - Ton b lng khun c in y kim loi - Dng kim loi phi chy u, m, khng va p vo lng khun. - H thng rt phi chc khng b v Thit k cc b phn ca h thng rt .
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
6.Cc loi cc rt
7.ng rt
. - ng rt : ng rt dng dn kim loi t phu n rnh lc x, ng rt c nh hng ln n tc chy ca kim loi vo khun c, p lc ca kim loi ln thnh khun c ph thuc vo chiu cao ng rt. Chiu cao ca ng rt cao hn mt cao nht ca vt c trong lng khun mt khong (100 200 ) mm a.5.xc nh khch thc ng rt .a.6- Rnh lc x : Rnh lc x c b tr nm ngang chn x i vo lng khun. N c b tr trn rnh dn, nhm t cho x
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
nh ni ln trn v li trong rnh lc x, cn kim loi sch theo rnh dn vo khun
8.Rnh lc x Cc loi rnh lc x: a-rnh lc tit din hnh ngang b- rnh x c mnh lc hoc mng ngn c- rnh lc x gp khc v nhiu bc a7. Rnh dn : Rnh dn dng dn kim loi lng t rnh lc x vo lng khun. Nhim v ca rnh dn l khng ch tc v hng ca dng kim loi chy vo khun. Hnh dng v s lng ca rnh dn c nh hng rt ln n cht lng vt c. Chn tit din ca rnh dn l hnh thang dt v u im ca rnh dn ny l d ni x, d ct rnh dn khi vt c, gim khuynh hng to thnh xp co ch dn kim loi vo lng khun.
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
Chn ch dn kim loi vo khun hp l bo m c s in y lng khun u n, trnh c nhng ng sut bn trong v r co tao ra trong vt c. Khi lng ca ming lt ray tu khng ln lm, v c dng hnh tr ta dn kim loi vo mt pha a.1.xc nh khi lng vt c . Khi lng kim loi chy qua cc rnh dn bng khi lng vt c ( k c h thng rt, u ngt ) Ta c : F .V .t. =G (1) F Vi : Tng thit din rnh dn (cm2) V : Vn tc kim loi chy qua h thng rt (cm/s)rd rd
t : Thi gian kim loi chy qua h thng rt (s) G : Khi lng vt c ( k c u ngt, h thng rt )
: khi lng ring ca kim loiGrd
F Ta c : = V .t. (cm2) (2) = 6,8 (g/cm3) F tnh c th phi bit c khi lng ming ltrd
ray tu ta c : Mml = m1 + m2 -m3 - m4
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
Trong : m1 : khi lng lng phn tn ca ming lt m2 : khi lng tr pha di ca ming lt bao gm c phn vt m3 : khi lng hnh tr rng ca ming lt m4 : khi lng phn vt Ta c : m1 = .V1 =.a.b.c thay s vo ta c m1 = 6,8.0,02.0,04.0,025 = 0,157 (kg) m2 = .V2 = .a.b.c thay s vo ta c m2 = 6,8.0,09.0,07.0,025= 0,1,236 (kg) m3 = .V3 = ..R 2 h thay s vo ta c m3 = 6,8.3,14.(0,015)2.0,025 = 0,138 (kg) a.b m4 = .V =. 2 .c4
.0,07 = 0,0275 (kg) thay s vo ta c m4 = 6,8. 2 mml = 0,157+1,236-0,138-0,0275 = 1,23 (kg) G = 1,23 (kg) Theo cng thc becnuli trong thu ng hc th :
0,01 .0,01
a.2. xc nh (v) h s cn thy lc V = 2 g .H = 0,58 Trong : : h s cn thu lc, chnp
= 0,4
g : gia tc trng trngG 2.g .H p .t.
g = 9,8 (m/s2)
HP : chiu cao trung bnh tnh ton ca p sut(cm) T ta c Frd
=
(3)
a.4. xc nh Hp.GVHD: NGUYN B THUN SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
Tnh HP chiu cao tnh ton ca ct p sut c tnh theo cng thcHp =H P2 2C
Trong : H : chiu cao ca ng rt t ch dn kim loi n mt thong (cm) C : chiu cao ca vt c (cm) P : chiu cao vt c tnh t ch dn kim loi vo khun tr ln (cm) rnh dn mt phn khun nn ta c Thay (4) vo (3) ta c :Hp =H G C .t. 8 C 8
= 0,11 (4) (5)
F
rd
=
2g H
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
9.S tnh ton ct p sut Thi gian kim loi chy trong rnh dn t c tnh theo cng thc thc nghim sau : a.3. xc nh thi gian rt t t = K G = 1,88 (s) chn K= 1,7 Thay t vo cng thc (5) ta c ViFrd = G
..K . 2 g . H
= 0,4 K =1,7 H = 0,12 ( m ) C = 0,055 ( m )
= 6,8( g / cm 3 )
C 8
G =1,23 ( kg )
Thay s vo ta cFrd = 1,23 0,055 6,8.0,4.1,7. 2.10 . 0,0.12 8 = 1,29 ( m 2 ) = 1,29 (cm 2 )
GVHD: NGUYN B THUN
SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loird
Vt liu c bng thp nn ta c t l F Trong : FrLX : l din tch rnh lc x For : l din tch ng rt Ta c FrLX = 1,29 .1,1 = 1,419 ( cm 2 )For =1,29 .1,2 =1,548 (cm )
: FrLX : For =1 : 1,1 : 1,2
Ta c ng knh ca ng rt phn di c tnh :dD = 4 For
=
4.1,548 = 1,4( cm ) 3,14
ng knh ng rt gn cc rt dR c ly ln hn dD 15% Ta c d r = d D + d D .0,15 = 1,4 +1,4.0,15 = 1,61( cm ) 5.2 Tnh lc khun.Sau khi lp khun, ta phi dng bu lng kp cht hai na phn khun hoc t mt ti trng ln khun trnh cho kim loi lng khng th nng khun trn ln v trn theo mt phn khun ra ngoi. Lc khun phi ln hn lc y acsimt ca kim loi lng ln khun. Tng lc y ln khun trn c tnh theo cng thc :
Pd = Pdkt + Pdl
Lc khun :
Q = ( P G KT ).n
n : H s an ton
GKT = GCt khun + GHm khun ; GHm khun = 15% GCt khTa c ;Gct khun = 120.120.100.10-9.7848 =11,3 (Kg) Ta c lc y khun trn l Pdkt = .V V : Th tch c gii hn mt y l phn b mt tip xc vi kim loi lng ( vt c ) chiu cao tnh t mt n mt thong kim loi cc rt
: khi lng ring ca vt liu kim loi
Vi V = 100.70.120 .10-9 = 8,4.10-4 m3 Pdkt =8,4. 10-4GVHD: NGUYN B THUN SVTH: L QUANG PHONG
Bi tp ln
Mn: Cng ngh kim loi
Lc y acsimt tc dng ln li Pdl = (35.222.3,14.7848.10-9)/4 = 0,1( Kg) Ta co ; P = Pdkt +Pdl = 0,1 . 0,6 = 6,7( Kg) Nn Q =(P Gkt ).n = 6,7 11,3= - 4,6 (Kg) n : h s an ton ; n= 1,5 V Q
