Page 343 - Analysis and Design of Machine Elements

Example Problem 11.4 Rolling Contact Bearings 321
A single-row, deep-groove ball bearing 6210 is subjected to the following set of loads
and operates at the listed rotational speeds for the given percentage of time:

Applied Rotational Time percentage
Condition load P (N) speed n (rpm) a (%)
i i i
1 5400 150 30
2 2000 200 50
3 1000 750 20
This load cycle is repeated continuously throughout the life of bearing. Estimate the
total life of the bearing.
Solution

Steps Computation Results Units
1. Basic dynamic From bearing catalogues or Table 11.2, the basic dynamic C = 35 000 N
load rating C load rating C of the bearing 6210 is 35 000 N.
2. From Eq. (11.28) L = 88 924 h
h
10 6 C
L = ×

h 60 a n P + a n P +···+ a n P n
10 6 1 1 1 2 2 2 n n
= ×
60
35000 3
=
3
3
0.3 × 150 × 5400 + 0.5 × 200 × 2000 + 0.2 × 750 × 1000 3
88924
References
1 Mott, R.L. (2003). Machine Elements in Mechanical Design, 4e. Prentice Hall.
2 Hindhede, U., Zimmerman, J.R., Hopkins, R.B. et al. (1983). Machine Design Funda-
mentals: A Practical Approach.New York:Wiley.
3 Juvinall, R.C. and Marshek, K.M. (2011). Fundamentals of Machine Component
Design, 5e. New York: Wiley.
4 Wen, B.C. (2015). Machine Design Handbook, 5e, vol. 3. Beijing: China Machine
Press.
5 Pu, L.G. and Ji, M.G. (2006). Mechanical Design, 8e. Beijing: Higher Education Press.
6 Harris, T.A. and Kotzalas, M.N. (2007). Essential Concepts of Bearing Technology,5e.
New York: CRC Press.
7 Oberg, E. (2012). Machinery’s Handbook, 29e. New York: Industrial Press.
8 Li, F. and Ma, Y. (1993). GB/T 272-1993 Rolling Bearing--Identification Code. Beijing:
Standardization Administration of the People’s Republic of China.
9 Li, F. and Ma, Y. (2007). GB/T 276-2013 Rolling Bearings – Deep Groove Ball Bear-
ings – Boundary Dimensions. Beijing: Standardization Administration of the People’s
Republic of China.