rolling element bearings-1
TRANSCRIPT
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Rolling Element Bearings prepared by
Wayne Book
ME3180
Based on Shigley and Mischke
and Budynas and Nisbett
esign o! Mechanical Elements
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Rolling Element Bearings
"utline# Bearing types and nomenclature
# $oads% li!e and !ailure modes
# Ball bearing selection criteria
# &apered bearings
' (nduced thrust load
' Selection
# )pplication and maintenance
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Ball Bearing Nomenclature*+rom Shigley,
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Roller Bearing Nomenclature*!rom Shigley,
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-lassi!ication ' Ball Bearings
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-lassi!ication ' Roller Bearings
*Norton,
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&ypes o! Ball Bearings
*!rom Shigley,
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&ypes o! Roller Bearings*!rom Shigley,
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Bearing $oads
Bearings are rated by radial loads + at a rating li!e $R
&hrust is included by increasing radial load to +e
- . basic load rating at $ . 10/ cycles *unusable,
&hrust
Radial !orce +Sha!tBearing
ousing
Speed
n
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+ailure o! bearings
# )ssume dirt% heat etc are not ma2or !actors
# +atigue spalls contact sur!ace due to cyclical
contact loading# itting o! signi!icant area de!ines use!ul li!e
# $10 li!e is the li!e e4ceeded by all but 105 o!
the bearings
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$i!e6$oad Relationships
=
=
=
=
bearingsroller1073%
bearings ball%3
loadRadial
re7minnspeedathoursorsreolutionin$i!e
1
9
9
1
a
F
L
F F
L L
a
Note: (! +1 . -% the basic load% then $1 . 10/ re7min *typical%
&imken uses ;0410/,< $ re . $hours 4 n 4 /0
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&ypical data: load s li!e< reliability
;05reach
li!e $
esign reliability higher . R redicted by Weibull distribution
+7$a .
constant esign
point
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)d2ustment o! -10 !or Reliability% etc
# esign !orce +% li!e$% and reliability R
# Weibull parameters
!rom endor:
' x0 , b, (θ-x0 )
# +ind normali=ed li!e
x D = L/L10
# -alculate ad2ustedrating
,>11*;00<,1,**
71
71
00
10 −≥
−−+
= R R x x
x F C
a
b
D
D D
θ
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-ombined Radial and )4ial $oads
# Nondimensionali=e e?uialentand a4ial loads
# lot nondimensionali=ede?uialent load snondimensionali=ed a4ial load
# )ppro4imate @ith t@o straightlines
# &hree parameters depend onratio o! a4ial load7rated load% seetable 1161
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E?uialent Radial $oad
table!rom!actor&hrust
table!rom!actorRadial
ringouterrotating19%
alingning6sel! orringinnerrotating1% !actorrotation
load*a4ial,thrustappliedloadradialapplied
loadradiale?ui8alent
ma4
=
=
==
==
=
+=
Y
X
V
F F
F
YF XVF
VF F
a
r
e
ar
r
e
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E4ample $oad +actors *!rom Shigley,
&able 1161
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)+BM) Si=e lan*!rom Shigley,
+igure 116>
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E4ample imensions A Ratings*!rom Shigley,
&able 1169
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Steps in Si=ing Ball Bearings
# ien +r % +a
# Select a trial bearing si=e !rom &able 1169
' +ind -0 and -.-10
# &able 1161 '
(nterpolate based on +a7-0 to get e ' -ompare +a7+r to e% select either C1%D1 or C9%D9
# -alculate e?uialent radial load +e
# -ompute li!e
# Select another bearing i! not satis!actory and repeat
a
e F
C L
=
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E4ample -alculations
# )n 09 series bearing @ith bore o! 30 mm
carries / kN radial and 98 kN applied
thrust -onsider both deep groe and
angular contact bearings
# +ind the radial and thrust !actors
# What is the predicted $10 li!eF
# +or the gien +r %at @hat alue o! +a doesthe thrust load begin to in!luence the li!e o!
the bearingF
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"ther Empirical +actors*!rom Shigley,
&able 116G
&able 116