Page 448 - Cam Design Handbook

THB13 9/19/03 7:56 PM Page 436

436 CAM DESIGN HANDBOOK

FIGURE 13.19. Dynamic model for high-speed cam-follower
system.

Substituting in Eq. (13.78) gives

dy
2
L
y
k
-ky - - S 1 - (y - ) = m .
s
f
c
dt 2
Solving for cam displacement,
LS k + k s m dy
2
+
f
y = 1 + + .
c (13.79)
k k k dt 2
f f f
In Eq. (13.79), it is convenient to change the independent variable from time t to the
cam angle q, degrees. We know that
2
dy dy
2
= w 2 . (13.80)
dt 2 dq 2
Substituting gives
2
dy 2 Ê deg ˆ 2 Ê N ˆ Ê rev ˆ 2 d y
2
2
= 360 ¥ ¥ = 36 Ny¢¢. (13.81)
2
dt 2 Ë rev ¯ Ë 60 ¯ Ë sec ¯ dq 2
Substituting in Eq. (13.79) yields the cam displacement
+
LS k + k s m
f
y = 1 + y + 36 Ny¢¢. (13.82)
2
c
k f k f k f
Rewriting,