การออกแบบ design.pdf
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Design of machine elements
--
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(Design of Machine Elements) --
().( )
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1. 4 2 14 3 25 4 (Static Strength) 32 5 37 6 47
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1
1.1 1.1.1
(Rigid)
1.1.2
1.1 1.
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1.1
2.
3.
4. 3
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(Standard part) (Drawing) (Detail drawing) (Assembledrawing) ()
5.
1.1
6.
(report)
1.2
1. 2.
3.
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4.
5. ()()()()
6. 7.
8.
1.3 1.3.1
(cold working )
(recrystallization temperature)
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(quenching )
( aging age hardening )
( decarburization )
(hot rolled) (forging) (heat treatment)(elasticity)
(malleability)
(ductility)
(toughness)
(hardness)
(stiffness)
(free carbon)
(temper carbon)(Killed steel)
(hardening) (Transformation range)
(austenite) (Machinability) (Tempering) (tempered)
(normalizing) (Normalizing)
38 C
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(Plasticity)
(Rimmed steel)
(Annealing)
1.3.2
(Wrought iron) (Slag) 1% 3%
1.5% 3.5% 1.11.1,
(()
3.25%, N/mm2, N/mm2(200mm),%,%
290 360
180 240
25 40
40 55
380 415
380 345
25 30
35 45
(Cast iron) 2.5 4 % (Compressive strength)
(White cast iron) (Cementite)
(Malleable cast iron)
880 C
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(Gray cast iron)
2.5% 4.0% 2%
(Nodular) (cerium)
(creep)
1.3.3
(Bush)
1. 2.
3.
4.
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5. (martensitic)
6. 7.
8.
9.
10. ()
11.
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3.5% 8.5%
250 ASTM SAE
2 (bronze)
(20 % )
(phosphor bronze) (silicon bronze) (aluminium bronze)(manganese bronze)
ASTM A Z K M H E rare earth
500 B 1112 100
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1105C
(Saturated) (Unsaturated) 2 (Thermosetting) (Thermoplastic)
(Filler) 2
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2
2.1 (Stress ) (Strain )2.1.1
(Stresses) (Strains)
()
A
F=
2 (tensilestresses) 2.1(a) (compressive stresses) 2.1 (b)
(+) (-) (Shear stresses) 2.1 (c)
3 (Principal stresses) 2 () 0 90 2.1
2.1
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Residual stresses residual stresses
Bearing stresses () (projected area)A = LD ( L ) 2.2
Bering stresses b=LD
F
A
F=
2.2 Bearing stresses
Elastic deformation
plasticdeformation
Elastic Plastic Elastic PlasticYield point
plastic deformationElastic Plastic
Elastic Plastic Yield point
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Stress Strain diagram 2.3
Stress Strain diagram Elastic Plastic Yield stress, YUltimate stress, uY
u 2.3
Stress Strain diagram
Yield point Yield point 0.1 0.2% offset yield stressyield stress 2.3
2.3 Stress Strain diagram
(Mild steel)
Brinell hardness number (BHN)
400 Yield stress Ultimate stress
y 0.6y u 0.6u
Youngs modulus
Youngs modulus Modulus of elasticity
E =
t
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t elastic ( t
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0.0127 (0.5) (Allowance) 0.0508 (2 )
y
(Variableload) (Fatigue)
(Endurance limit) n y
n u u
(Safety factor Design factor) y
2.2 2.2.1
(Working stress) (Designstress) 700 MN/m
2 420 MN/m2
140 MN/m2
5140700 ==uN
3140
420N y ==
Nu= .
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Ny=
1.
2. 3. 4.
5.
2.1
2.1 Ny Nu Nu
1.5 2 3 - 4
3 6
4 8
5 7 10 - 15
5 6
7 8
10 12
15 20
(Repeated, one direction) (Repeated and reversed)(Dead load)
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2.2.2 2.4 AISI C 1020 30 kN h = 1.5 b
) ) )
0 30 kN
2.4
AISI C1020
2
y
2
u
331N/mm)(48)(6.89548ksi
517N/mm)(75)(6.89575ksi
===
===
) 1.3 Ny = 1.5
2
td220.70N/mm
1.5
331==
)5.1)(( bb
F
bh
F
A
Ft ===
2b5.1
1000x3070.220 =
b = 9.52 mm. h = (1.5)(9.52) = 14.28 mm.
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) Nu = 3 2
td mm/N30.1723
517==
2
2tmm/N30.172
b5.1
F ==
172.30 = 30x1000
1.5b2
b = 10.77 mm. h = (1.5)(10.77) = 16.16 mm.
) Ny = 3 331/3
2b5.1
1000x30
3
331 =
b = 13.50 mm. h = (1.5)(13.50) = 20.20 mm.
) )
) b = 10 mm. h = 14 mm.
) (Fatigue)
2.2.3 (torque)
GJ
TL=
T L J (Polar area moment of inertia)
J =4
d32
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J = ( )idd32
44
d di
J
Tr=
r
nT2TWp ==
pW WT Nm
red/sn rev/s
hp =63000
Tn
T in lbn rev/min
(Thin walled tube) R 2.5
2.5
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= GRt2 2TL3
=2
Rt2
3T
2.2.4
1/10 2.6 () ()
. . 2.6
F = pLDi p Tangential stress , St
St = A
F
= 2tL
pLDi
= 2t
pDi
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F = pD 2i / 4 A = (D0+ Di) t / 2
Transverse stress, Stv
Stv
=F
A= p
2
iD
4
/
2
)tD(Di0
+ =
)tD2(D
D
i0
2
i
p
Transverse Stress tangential stress
=
(Effective wall thickness) th N Np
t =S2
NpDi
t =)SD(D2
NpDi
i
0+
S
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3
3.1 3.1.1
(Combined Stress) 3.1 F () () P
Torque (T) (Torsional Sharing
Stress )
3.1
2
F P X x T xy
X = b + t
X = 3d
32M
+
2d
4F
,
xy=
3d
16T
X = -b + t
X = - 3d32M
+2
d4F
, xy= 3d
16T
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3.2 () F Fa F
X = b + t , xy= 0
X = 3d
32M
+
2d
4F
X = -b+ t , xy= 0
X = 3d
32M
+
2d
4F
() () 3.2
3.2 () F Fa F
X = -
b - c ,
xy= 0
X = - 3d
32M
-
2d
4F
X = b- c , xy= 0
X = 3d
32M
-
2d
4F
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=
yx
xy
2tan2 1
3.1.2 (Differentiate) n
(Principal Stress)
2
+= + 2xy
2
22
,yxyx
21
1x x 45 - 145
3.2 3.2.1 Stress Element
35 P F Stress Element 3.5 3.6T PStress Element
Stress Element Stress Element
3.5 3.6
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3.2.2 3
2 (Mohr s circle)
1. ()
2. (x,
xy) (
y, -
xy) ,
3. 2
c
3.74. 2 3.7
xy
.......... ...........
3.7
123
max(1)
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2
21 +
max = 2
1
2
2
max =2
minmax
12 ()
1
2
max =2
21
.......... ...........
12 1 2
max = 2 31
=21
3.8
x y 0 3.8
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= + 22
22, 21
1
2
= + 22
2max
3.2.3 Stress Element Mohr s circle
3.9
x= 80 MPa
xy= 50 MPa
Stress Element
() () 3.9
3.9 ()
1 0 1 = 104 MPa 2 0 2 = -24 MPa
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max 1 C E = 64 MPa ()
2 C F = -64 MPa ()
1x 251.8 1 25.9
1 Mohr 2= 38.2 x = 19.1
3.10 () ()
.......... ...........
() () 3.10 Stress Element
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4(Design for Static Strength)
4.1 (Failure Theories)4.1.1 (The Maximum Normal Stress Theory )
(Maximum absolute value)
(3= 0) N
1 = -
N
y
21
>
2 = -
N
y
12
>
x =y
1 y =y
2
x = 1 , y = 2
4.1 ()
() () 4.1
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4.1.2 (The Maximum Shear-Stress Theory)
(Trescas criterion)
45
max
y/ 2
2
21 =
2
y
2
1 =
2
y
2
2 =
2
y
21 = y
1 = y
2 =
y
x-y = 1 , x= 1 , y = 1
x y
max = y
1
=
2/122
+
yy
y= y/2
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4.1.3 (Octahedral ShearStress Theory) (distortion energy
theory)
(plasticity) von Mises
(Octahedral plane)
ABC 4.2 (directional cosine) 3/1 oc
4.2
oc = [ ] [ ] [ ][ ]2/12
13
2
32
2
213
1 ++ (4.1)
2
3
1 = y (4.1) 2= 3= 0 1= y
= y3
2= 471.0 y (4.2)
oc
=
2 y2 = [ ] [ ] [ ]213
2
32
2
21 ++ (4.3)
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3= 0
N (4.3) 2
y= 2
2
2112 + (4.4 )
1 = 22 +
2 3/2
4.2
4.2A B C D E F GH
()
4.2
y
= [ ] 2/122 3 +
1
=
2/122
3
+
yy
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y =3
y= 0.577 y
2/122
1
+
= yy
(Maximumprincipal strain theory) (Maximum strain energy theory)
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5
5.1 5.1.1
(Fatigue)
5.1.2 (Discontinuity)
F
F
max (
0 = F/A) (Stress concentration factor)
K =0
max
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5.1
(Microscopic)
5.2 5.2.1
(Fatigue limit) (Reversed stress) 8 mm
. .
5.2 . .
F
F
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5.2.2 3
(Reversed bending) 5.2 .
5.3
A 5.3 () 8 mm A 50% (Iinfinite life) 1
5.2.3
A
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(50%)
n = 0.5u n = 690 N / mm2 n = 0.4 u n = 0.35 u
(106 )
n = 0.45 u n = 0.38 u 275N/mm
2(5x108)
n = 0.16 u 345N/mm
2(5x108)
5.3 5.3.1 (Surface factor) ka
5.4
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5.4 (Surface factor) ka
5.3.2 (Size factor) kb
8 mm
kb = 1.00 d < 8 mm
kb = 0.85 8 < d < 50 mm
kb
= 0.75 d > 50 m
(hb)0.808d= h
b
kb
= (d/7.62)-0.1133
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5.3.3 (Load factor) kc
kc
= 1.00
kc
= 0.80
kc = 0.60
5.3.4 (Temperature factor) kd
kd =1 {t350 c}
kd =0.5 {350
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q = 0 Kf= 1
q = 1 Kf= Kt
Kf= Kt () K
f= K
t
Kf
4.5 q
5.4 5.4.1
(Soderbergs Criterion) ()
() ()
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()5.6
(Sinusoidal) 5.6 () () 5.6 () 5.6 ()
R =
max
min
min max R = 0 5.6 ()R = -1 5.6 ()
5.4.2 (Soderbergs Criterion)
a =2
min-max (Stress amplitude)
m =2
minmax + (Mean stress)
am
a = A
aF
IC
aM
AFa
a = J
ra
T
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m=A
mF
I
Cm
M
A
mF
m =J
rm
T
Fa, M
a, T
a, F
m, M
mT
m
Fa =2
Fmin-Fmax
Ma =2
Mmin-Mmax
Ta =
2
Tmin-Tmax
.......... ...........
Fm =
2
FminFmax +
Mm
=2
MminMmax +
Tm =2
TminTmax +
AB
am AB AB N GE
4.7 GE DEF ABC
AC
DF=
BC
EF
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n
a
=
y
m-/N
y
N
1=
y
m
+
n
a
(Proof stress) (Goodman) B 4.7
N
1=
u
m
+
n
a
Kf
a
m
N1 =
y
m
+
n
af
K
N
1=
u
m
+
n
afK
(Gerber)
N
1=
y
m
+
n
afsK
Kfs
1)-q(K1Ktsfs
+=
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6
6.1 6.1.1
(Shaft) (Axle)
(Spindle) (Head stock spindle)(Stub Shaft) (Head Shaft)
(Line Shaft) (Power transmission shaft) (MainShaft)
(Flexible Shaft) (Cable) (Wire rope)
(Rigidity) (Deflection) (Criticalspeed) (Ball bearing)
(Misalignment)
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6.1.2 (mild steel)
AISI
1347 3140 4150 4340 90 mm.
(Nominal size) ISO/R 775-1969 6.1
6.1 ISO/P 775-1969
mm.6
7
8
9
10
12
14
18
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
110
120
130
140
150
160
170
180
190
200
220
240
260
280
300
320
340
360
380
6.1.3 ASME
(Cam shaft )
0.3 1 m.
1 20
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0.5
(Clearance) (Contact ratio)
0.08 mm./m.
(Spur gear) 0.125 mm. 0.286
(Bevel gear)
0.075 mm.
(Double integration) (Moment area)
ASME
..2497 (ASME) ASME (Static design method) 6.1
di
d
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6.1
)(
422
i
add
F
=
)(
3244
i
bdd
Md
I
Mc
==
)(16
44
i
xydd
TdJTr
==
(buckling)
)(
422
i
add
F
=
ASME (Fatigue factor)
Cm = C
t=
6.2
Cm Ct : :
1.0
1.5-2.0
1.5
1.5-2.0
2.0-3.0
1.0
1.5-2.0
1.0
1.0-1.5
1.5-3.0
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ba +=
/ddK i= F
K = di/d = 0
ASME
1= F
( ))/0044.011
kL= 115
k
L 6.1
( )
nE
kLy
2
2/
= 115>
k
L 6.2
n = 1.00 SS
n = 2.25 CC
xy2
2
max2
+
=
( ) ( )
22
24
3
8
1
1
16
+
++= MC
KFd(TC
)K(d mt
( ) ( )224
3
1
16MCTC
)K(d mt +
=
( ) ( )22316
MCTC
d mt +=
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n = 1.60 (partially restrained)L = 6.1 (Straight line formula)
6.2 ASME
d = 55 N/mm2
d = 41 N/mm2
7.3 d = 0.3y d = 0.18y 6.3
75 % 6.3
6.2 6.2.1
(Pulley) (Friction Wheel) (Gear)
6.2
(y)
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EI
FLy
48
3
max= EI
FLy
3
3
max =
y mm.
E = 200 kN /mm2 I = 80 x103mm4 6.3
6.3
EI
FLy
48
3
max=
)1080)(10200(48
600)10(1033
33
maxxx
xy =
81.2max=y mm.
6.2.2
. .
(Critical speed) nc
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6.4
6.4 W1 W2 W3 y1y2 y3
++
++=
2
33
2
22
2
11
332211945yWyWyW
yWyWyWnc
m
=
2
945Wy
Wync
m W Ny mmn
c rpm
() 25 %
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6.2 6.2.1 6 6 1. 6.5 (A)2. 6.1 (B)3. 6.5 (C)4. (Bearing Crushing)6.5(D)5. 6.5 (E)6. 6.5 (F)
6.5 6
6
6.2.2
()
=
6.4
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(t)
t =
td2
pD
6.5
p D
td
6.3
6.3
50-60 60-75
65-80 55-65 65-80 80-88 90-95
6.2.3
ASMEBoiler Code
1. ASME Boiler Code 6.4
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6.4
(D) (mm)
(t) (mm)
900925-1350
1375-1800
1800
6.00
7.90
9.40
12.50
6.4 6.4
6.4 t 6.4 BS DD5 ( mm)
6 8 10 12 15 18 20 22 25 28
30 32 35 38 40 45 50 55 60
ut = 380 N/mm2
uc = 655 N/mm2
u = 300 N/mm2
5
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6.5 (mm) (mm)
600-1800
900-2100
1500-2700
5-12
8-25
9-23
d = 6.6 t 6.6
t mm
(Solid plate) 6.3
() 6.5() 6.3() (6.5)
6.4 () (6.6)()
()
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6.3
6.3.1
mm mm x
16mm () M16
20mm 2 mm M20x2
M30-LH (LH = Left Hand )
ISO/R 261-1969 (E)
1. 1 2
2.
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P
() () (.) 1 2 1.00 0.25 0.838 0.693 0.729 0.456
1.20 0.25 1.038 0.893 0.929 0.730
1.60 0.35 1.373 1.170 1.221 1.270
2.00 0.40 1.740 1.509 1.567 2.070
2.50 0.45 2.208 1.948 2.013 3.390
3.00 0.50 2.675 2.387 2.459 5.030
3.50 0.60 3.110 2.764 2.850 6.780
4.00 0.70 3.545 3.141 3.242 8.780
4.50 0.75 4.013 3.580 3.688 11.300
5.00 0.80 4.480 4.019 4.134 14.200
6.00 1.00 5.350 4.773 4.917 20.1008.00 1.25 7.183 6.466 6.647 36.600
(9) 1.25 8.188 7.466 7.647 48.100
10.00 1.50 9.026 8.160 8.376 58.000
(11) 1.50 10.026 9.160 9.376 72.300
12.00 1.75 10.863 9.830 10.106 84.300
14.00 2.00 12.701 11.546 11.835 115.000
16.00 2.00 14.701 13.546 13.835 157.000
18.00 2.50 16.376 14.933 15.294 192.000
20.00 2.50 18.376 16.933 17.294 245.000
22.00 2.50 20.376 18.933 19.294 303.000
24.00 3.00 22.051 20.319 20.752 353.000
27.00 3.00 25.051 23.319 23.752 459.000
30.00 3.50 27.727 25.706 26.211 561.000
33.00 3.50 30.727 28.706 29.211 694.000
36.00 4.00 33.402 31.093 31.670 817.000
39.00 4.00 36.402 34.093 34.670 976.000
42.00 4.50 39.077 36.479 37.129 1120.000
45.00 4.50 42.077 39.479 40.129 1300.000
48.00 5.00 44.752 41.866 42.587 1470.000
52.00 5.00 48.752 45.866 46.587 1760.000
56.00 5.50 52.428 49.252 50.046 2030.000
60.00 5.50 56.428 53.252 54.046 2360.000
64.00 6.00 60.103 56.639 57.050 2680.000
68.00 6.00 64.103 60.639 61.505 3060.000
6.6
6.3.2
1. (Bolt and nut)2. (Cap Screw)
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3. (Stud bolt)4. (Machine screw)5. (Set Screw)
1.
. . .
. . 6.6
2. 6.6 ()
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3. 6.6 ()
.
.
.
4. 6.6 ()
5. 6.6 () d D d = 0.125D + 8 mm
6.3.3
1. 2. 3. 4.
5.
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6.4 6.4.1
1.
2.
1.
ISO/R 773 6.8 (hub) (Feather key)
A B C
6.8
6.8
2.
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2 ISO2491 1:10 ISO 2492
3. (Saddle key) 6.9 () 6.9 ()
. .4. (Woodruff key )
6.10 (A)
b ISO 3912 6.10 (B) h2 = 0.8 h1 75 mm.
5. (Tangential key ) 6.11 ISO 3117 2 2 180
6.9
6.10
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6.11
6. (spline) 6.12
ISO /R 14
6.12
7. (Overload ) (shear pin)
6.4.2
2 1.
2.
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(Torsional stiffness)
6.13 ()
. .
6.13
. .
6.14
6.14 F F F F
242
FdhdFT
+=
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, 6.7
T F d b l
, 6.8
h
cd 6.7 6.8
1/2 = 0.5y
b = h
22
dblFdT
==
ldb
T
A
F
..
2==
lhd
T
A
Fc
..
4==
42
dhlFdT c
==
42dhldbl c =
162
3 ddblT ==
b
dl
8
2=
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d/4
1.57
(6.1 ) (6.2)
6.7 6.7 2180
(6.1)(6.2)
6.7
(6.8) (6.1) (6.9)
(Effective length) le
6.9
le
ddl 57.12
==
6 8 10 12 14 16 18 20 22 25 28 32 36 40 45 50 56 63 70 80 90 100
110 125 140 160 180 200 220 250 280 320 360 400
lhd
Tcd
..
4=
cd
ehd
Tl
..
4=
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cd
(6.9) 25 %
6.4.3
75 %
l dm = (D+d)/2h = (D-d)/2
NyNy = 1.5 Ny = 2.5 Ny = 4.5
600 N/mm2ISO
600 N/mm2
cd
m
czlhd
T =
75.0.
2
cdm zhd
Tl
75.0
2
y
y
cdN
=
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38 mm 70 mm 600 N/mm2
320 N/mm2
900 Nm 38 mm ISO/R 774-A10 x 8
3.5
cd = 320/3.5 = 91.43 N/mm2
2 70 mm ISO/R 774-A10x8x70 2
6.4.5 (Pins)
1.
ISO 2338
6.8
6.15
cd
ehd
Tl
..
4=
43.91838
10009004
xx
xxle = 52.129= mm
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2. 1:506.16 ISO 2339 A B
6.16
6.8 ISO 2338
d
l
d
l
0.6
0.8
1.0
1.2
1.5
2.0
2.5
3.0
4.0
5.0
2-6
2-8
4-10
4-12
4-16
6-25
6-25
8-30
8-45
10-50
6.0
8.0
10.0
12.0
16.0
20.0
25.0
30.0
40.0
50.0
12-60
14-80
20-100
25-150
30-180
40506080100
3. (Clevis) 6.17 (Split pin) ISO 2340
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6.17
4. 6.18 ISO 2341
6.18
5. 6.19 6.8
6.19
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I
Mc3d
M32
A3
V4=
2d d3
F8
=
A
Fcd =
6.2.2 (cotter) ( socket) 6.20
6.20
cd td = =
CD
V = F/2 A
A A= dl
A=2d
s
A
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s
2
1
dd
T4
A
F
==
sdD
T2
+
N
y = 2.0
Ny = 2.5 N
y = 3.5
6.21
6.21 F
1=T/d
s
25 %
F 6.21
F =
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F
6.5 6.5.1
(Outer ring) (Innerring ) (Rolling element ) (Case) Rolling friction 25-50 %
2 1. Ball bearing
2. Rolling bearing
(Cylinder)
1. (Cylindrical roller bearing)
2. (Needle roller bearing)
3. (Taper roller bearing)
4. (Barrel roller bearing)
5. (Spherical roller bearing)
6. (Cylindrical roller thrust bearing)
7. (Spherical roller thrust bearing)
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6.22
6.5.2
(Diameter series) 8 9 0 12 3 4 8 4
(Width series ) 8 0 1 2 3 4 5 6 8 6 51309 5 13 d = 9 x 5 = 45 .
NU308 NU 03 d = 8 x 5 = 45 .
6.5.3
) 90 % B-10 (B-10 life) 3 50 %
Plain ball bearing 90 % Survival rpm x 60 x 106 106 90 % Survival 106/(rpm x 60)
) Ball ) Cylinder ) Taper ) Needle ) Spherical ) Barrel
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1
2
2
1
H
H
n
n=
n rpmH
1
2
2
1
B
B
F
F
k
k
=
F B k 3 -4 (k=3 ball bearing ,k=3.3 roller bearing
needle bearing )(B) (H)
B = H x rpm x 60
6.6
-
-
-
-
6.6.1
0.5%
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(helical spring) 12 mm
(wound cold) (wound hot)
(stress relieved) 260C 15 60
6.6.2
u x
A
d =
n y
B
d =
u N/mm2
n N/mm2
d mm
y = 0.60u
y = 0.47u
6.6.3 F 6.23 ()
Do Di D d
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6.23
F T 6.23 ()
Tr F
J A= +
2
FDT=
4( / 32)
/ 2
J d
r d
=
3
16
d=
2
4
dA
=
3 2
8 4FD F
d d
= +
C = D/d (Spring index)
3
8s
FDK
d
=
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KS = 1 +0.5
C
KS (Shear stress correction factor) F/A
Tr/J (Curvature correction factor) KC
K = KCK
S
4 1 0.615
4 4
C
C C
= +
K (Wahls factor)
=3
8FDK
d
=2
8FCK
d
6.7 6.7.1
4(Flat belt) (Round belt) (V belt) (Timing belt)
6.7.2 (Open belt) (Close belt)
6.24 (a)
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6.24 (a) (b)
6.24 (a)
C2
dDsin2 1d
=
C2
dDsin2 1D
+=
D = d = C = =
2
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[ ] )dD(2
1)dD(C4L dD
2/122 ++=
6.24 (b) 2
C2
dDsin2 1
+=
[ ] +++= )dD(2
1)dD(C4L
2/122