-
CHI TIT MY
-
TI LIU THAM KHO
1. C s thit k my - Trnh Cht
2. Tnh ton thit k h dn ng c kh (1,2) Trnh Cht, L Vn
Uyn
3. Chi tit my (1,2) Nguyn Trng Hip
-
Phn I. C S THIT K MY
Ch tiu:
- Nng sut, tin cy, tui th
- Chi ph
- An ton
-
=> Ni dung thit k my:
1. Xc nh nguyn tc hot ng, ch lm vic
2. Lp h s
3. Xc nh ti trng
4. Chn vt liu
5. Tnh ton thit k => kch thc
Xc nh hnh dng kch thc c th (kh nng lm vic, TC, )
6. Lp thuyt minh, hng dn
Kinh t
K thut
-
Chng 1 NHNG VN C BN
1. Gii thiu chung
1. Khi nim
- Chi tit my: n v nh nht hp thnh ca my (khng
nguyn cng lp rp)
-
- Nhm tit my: cc chi tit
u im:
- Tit kim kim loi qu
- D ch to
- D thay th
- B phn my: cc chi tit, nhm tit
- My
-
2. Phn loi
- CTM c cng dng chung
- CTM c cng dng ring
3. Hc phn Chi tit my
- Nguyn l lm vic, kt cu
- Phng php tnh ton thit k
-
2. Ti trng v ng sut
1. Ti trng
Khi nim
P
Ti trng lm vic
-
Phn loi
* Thay i theo thi gian
- Ti trng tnh
- Ti trng thay i
- Ti trng va p
* Tnh ton
- Ti trng danh ngha
- Ti trng tng ng
- Ti trng tnh ton
-
2. ng sut
c tnh thay i ng sut
ng sut khng i
ng sut thay i => chu trnh thay i ng sut
Ch bnh n
Ch khng bnh n
-
Loi ng sut
-
ng sut dp
=
.
-
ng sut tip xc
= .2
=212
[1 1 22 + 2 1 1
2
=121 2
-
= 0,3883 2
2
-
3. Cc ch tiu v kh nng lm vic
1. bn
- Kh nng tip nhn ti trng ca CTM m khng b ph hng
- Tc hi
- 2 loi:
+ bn tnh
+ bn mi
- iu kin m bo bn:
[]
[]
S [S] vi [S] = gh/[]
- Bin php tng bn
-
2. cng
- Kh nng cn li s thay i hnh dng di tc dng ti trng
- Tc hi
- iu kin m bo cng:
y [y]
[]
- Bin php tng cng
-
3. bn mn
- Mn: kt qu tc dng ca ng sut tip xc hay p sut khi cc b
mt tip xc trt tng i vi nhau m khng du bi trn
- Tc hi
- iu kin m bo bn mn
-
4. chu nhit
- Kh nng chi tit my c th lm vic trong phm vi nhit cn
thit m khong b nung nng qu mc cho php
- Tc hi
+ Lm cong vnh, thay i khe h gia cc chi tit
+ Gim bn (gin)
+ Gim nht
- iu kin m bo chu nhit
-
5. n nh dao ng
- Kh nng CTM c th lm vic trong phm vi vn tc m khng b
rung qu mc cho php
- Tc hi
- iu kin m bo
-
4. bn mi
1. Hin tng ph hy mi
3 giai on:
- Xut hin vt nt t vi
- Pht trin
- Hng
-
2. ng cong mi
=
-
3. th ng sut gii hn
-
4. Cc yu t nh hng bn mi
Hnh dng kt cu
Thay i tit din => tp trung ng sut
h s tp trung ng sut
=
; =
=; =
r
-
Kch thc tuyt i
nh hng
H s kch thc tuyt i:
=0
; =0
-
Cng ngh gia cng b mt
H s trng thi b mt : t s gia gii hn mi ca mu c trng thi
b mt ging chi tit v gii hn mi ca mu c b mt khng c
gia cng tng bn
-
Trng thi ng sut
nh hng ca ng sut trung bnh
-
5. Cc bin php nng cao bn mi
Bin php kt cu
Bin php cng ngh
-
5. tin cy
1. Khi nim
- Kh nng sn phm thc hin chc nng v duy tr trong thi gian
xc nh
- Khng m bo tin cy => thit hi
- c bit trong dy chuyn sn xut
-
2. Cc ch tiu nh gi tin cy
Xc sut lm vic khng hng
Xc sut khng xy ra hng hc trong thi gian nh
() == = 1 ()
() = =1
()
-
Cng hng
T s gia s hng hc trong 1 n v thi gian v tng s chi tit s
dng ti thi im
=
-
Tui th
Khong thi gian hot ng ca chi tit (my) t khi bt u hot ng
cho n khi hng
= 100 R(t) (%)
H s s dng
Ks = tlv/T = tlv / (tlv + tc + tp)
-
3. Phng php nng cao tin cy
Thit k
Ch to
S dng
-
6. Tnh ton thit k chi tit my
1. c im
- Thit k Kim nghim
- Chn trc thng s => thng s c trng
- Cng thc l thuyt + h s
-
2. Chn vt liu
Yu cu
- Ch tiu v kh nng lm vic
- Khi lng, kch thc
- iu kin s dng
- Tnh cng ngh ph hp
- Gi thnh
-
Cc loi vt liu
Kim loi en Kim loi mu
Kim loi gm Phi kim
-
3. Xc nh ng sut cho php
[] = gh / S
Xc nh ng sut gii hn
- ng sut tnh:
+ Vt liu do: gh = ch (gii hn chy)
+ Vt liu gin: gh = b (gii hn bn)
- ng sut thay i n nh
N > N0: gh = r
N < N0: = . 0
-
- ng sut thay i khng n nh
- NE N0: gh = r
- NE < N0: = . 0
''
0
'
1
1
'
'
1 1
1
1
1
1 1 1 )
.
(
n mmn ni i mi i i i
i im mi ii i i i i
n m m m m
i i i r E
m
n
E i
i
ii
i
coNN N
NN N N
N N N N
nst
N N
-
Xc nh h s an ton
S = S1 S2 S3
Ti trng, ng sut
1,2 1,5
C tnh vt liu
1,5 2,5
Mc quan trng
1 1,5
