Page 384 - Cam Design Handbook

THB12 9/19/03 7:34 PM Page 372

372 CAM DESIGN HANDBOOK

x 2
m 2

k 2 b 2

x 1
m 1

k 1 b 1

y

Cam

FIGURE 12.9. Model of two DOF elastic fol-
lower, closed-track cam-follower system.

b b
z = 1 , z = 2 .
1 2
2 km 2 km
1 1 2 2

12.3.5 Some Cam-System Dynamic Phenomena

12.3.5.1 Balancing. In this section miscellaneous subjects of interest in the dynamics
of cam-follower systems are covered, such as the balancing of rotating elements of
the cam body, the crossover shock that occurs in closed-track cam-follower systems,
the spring surge (resonance) that occurs with open-track cams, and harmonic analysis of
cams.
The balance of the dynamic members of all complex machinery is a critical factor in
the performance. Thus it is with high-speed cam-follower systems. The imbalance of the
asymmetrical cam mass itself with respect to the center of rotation is the first issue of
concern. Obviously, strong vibrations are induced in the system at the cam speed funda-
mental harmonic. This vibration can be kept to a minimum, although not completely elim-
inated, by intelligent practical cam proportions, using a well-ribbed, low-mass structure
with designed counterweights as part of the cam body.
Some of the other sources of vibration due to imbalance that may be investigated for
cam-follower systems are: