Page 202 - Cam Design Handbook

THB7 8/15/03 1:58 PM Page 190

190 CAM DESIGN HANDBOOK

N

g

B A
C

r(q)
s(y) q

y

O F

FIGURE 7.6. Layout of a translating flat-face follower cam mechanism.

On the other hand, the curvature of the cam profile can be calculated by means of the
formula (Angeles and Lopez-Cajun, 1991)
1
k = (7.31)
ss
+ ¢¢
where s and s≤ are, respectively, the translational displacement of the follower and its
second derivative with respect to the angular displacement of the cam. The parameters
involved are displayed in Fig. 7.6.
7.4.2.2 Oscillating Flat-Face Followers. As in the previous case, the pressure angle
for oscillating flat-face followers is also constantly equal to zero. On the other hand, the
formula for calculating the curvature of the cam profile is given by Angeles and Lopez-
Cajun (1991)
(1 + f¢) 3
k = (7.32a)
F y ()
where
e
2
e +
F y () ∫ f¢¢cos f + (1 + f¢) ( [ 1 2 f¢)sin f + ( 1 f¢) ], e ∫ (7.32b)
+
l
f being the angular displacement of the follower and e as shown in Fig. 7.7.
7.4.2.3 Translating Knife-Edge and Roller Followers. The translating knife-edge fol-
lower shown in Fig. 7.8 is not usually found in practice, because of the large contact
stresses that it produces. However, it has theoretical and practical importance because its