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OLYMPIC C HC TON QUC 2014
Mn thi: NG DNG TIN HC TRONG C HC (CHI TIT
MY)
H thng dn ng cho hai xch ti (hnh 1).
Hnh 1
1. ng c; 2. B truyn ai thang nm ngang; 3. Hp gim tc 1
cp bnh rng tr rng nghing vi 2 trc u ra ging nhau; 4.
B truyn bnh rng cn rng thng (2 cp); 5, 6. Xch ti
Cc yu cu k thut cho trc: Lc ko mt xch ti F = 6000N, vn
tc xch ti v = 0,5 m/s, sai s cho php vn tc xch ti 5%, bc xch
ti pc = 100mm, s rng a xch ti z = 8 rng. T s truyn cp bnh
rng tr trong hp gim tc ubr1 = 5, bnh rng cn ubr2 = 2,5, thi
gian
lm vic L = 6 nm, ti trng tnh, 1 nm lm vic 252 ngy, mi ngy
lm vic 12 gi. S vng quay ng b ng c 1000vg/ph.
Phn 1 Phn tnh ton chi tit my (21) 1.1 Tnh cng sut cn thit, chn t
s truyn b truyn ai, chn ng c (bng 1) v lp bng cc thng s k thut.
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1.2 Thit k cc b truyn bnh rng tr rng nghing trong hp
gim tc
Yu cu: Tnh trn phn mm Autodesk Inventor theo tiu chun ISO
6336:1996, chn vt liu (theo tiu chun ISO: thp
A576-1060 nhit luyn vi gii hn mi tip xc sHlim 590MPa, h s an ton
SH = 1,2, SF = 1,3), xc nh thi gian
lm vic Lh, gc nghing rng , khong cch trc, mun rng, s rng, ng knh
vng chia, chiu rng vnh rng, dch chnh rng, vn tc vng ca bnh rng, lc
hng tm, lc vng, lc dc trc... M hnh 3D cc cp bnh rng. Lu : Cc h s KA
= 1; KHv = 1; KH = 1,2; KH = 1 khi
nhp trong Autodesk Inventor.
Cc kt qu a vo thuyt minh.
1.3 Thit k cc b truyn bnh rng cn Tnh bng Autodesk Inventor. Vt
liu theo tiu chun ISO:
thp A576-1060 thng ho (vi gii hn mi tip xc sHlim
520MPa, gii hn mi un sFlim 410MPa), h s KA = 1.
Chn ch tiu tnh v xc nh mun me, z1, z2 theo ISO
6336:1996. Xc nh cc thng s hnh hc, lc hng tm,
lc tip tuyn, lc dc trc. M hnh 3D cp bnh rng cn.
Lu : Chn cc h s ph hp tnh ton trn phn mm
Autodesk Inventor.
Cc kt qu a vo thuyt minh.
1.4 Thit k b truyn ai Chn trc: Chn k hiu ai, ng knh cc bnh ai
(chn d1 =180mm), khong cch trc (a =d2), chiu di ai. Yu cu:
Chn k hiu ai theo tiu chun DIN 2215, nhp cc thng s
d1, d2, L.
Tnh bng Autodesk Inventor: S dy ai z v cc thng s
b truyn: vn tc, lc cng ai ban u, lc vng c ch, lc
cng trn nhnh ai ch ng v b ng, lc tc dng ln trc,
gc m ai, b rng bnh ai, khong cch trc... bng
Autodesk Inventor. M hnh 3D b truyn ai.
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Cc kt qu a vo thuyt minh
Lu : Chn cc h s PRB = 4,0 kW, h s k1 = 1,2.
1.5 Thit k cc trc hp gim tc v chn then
+ Tnh bng tay: Xc nh ng knh s b, phc tho s b
kt cu trc vi [] = 30 MPa.
+ Tnh bng Autodesk Inventor: V s phn tch lc tc
dng ln cc bnh rng, bnh ai. nh kch thc cc on
trc, chn vt liu thp (Steel) vi Sy = 300MPa, nhp gi tr
cc lc tc dng ln trc, cc biu mmen un, ng sut.
M hnh 3D cc trc.
+ Chn then theo phn mm.
a cc kt qu vo thuyt minh.
1.6 Chn ln
+ Chn ln cho cc trc hp gim tc trong Autodesk
Inventor theo tiu chun.
a cc kt qu vo thuyt minh.
Phn 2 Phn m hnh ho chi tit my v cm chi tit my (11)
2.1 Hon thin m hnh cc chi tit v lp cm chi tit trn cc trc hp
gim tc, bao gm bnh ai, cc bnh rng tr, bnh rng cn, cc
ln
2.2 Th hin bn v 2D hnh chiu bng ca hp gim tc vi y
kch thc lp, dung sai.
a cc kt qu vo thuyt minh.
Phn 3 Phn phn tch chi tit my v la chn s ng (8)
3.1 Phn tch s ph thuc s dy ai z, ng knh bnh ai nh d1 ca b truyn
ai vo h s PRB (Base power rating). 3.2 Nu tc ng b ng c h thng truyn
ng trn hnh 1 l 1500vg/ph v cc yu cu k thut cho trc ca b phn cng tc
nh Phn 1.
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a) V s cc phng n dn ng h thng cho xch ti theo cc yu cu nu (3
phng n). b) Phn b t s truyn v chn ng c cho 1 s cu a).
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Lu : Lu cc file theo hng dn trong phng thi
Bng 1. S vng quay ng c in SGA, c
Cng sut, kW 2,2 3,0 4,0 5,5 7,5 11,0 15 18,5
n,
vg/ph
Vi s vng
quay ng b
1500 vg/ph
1430 1420 1440 1450 1450 1460 1460 1470
Vi s vng
quay ng b
1000 vg/ph
945 970 965 960 970 970 970 980
