Page 23 - Cam Design Handbook

THB1 8/15/03 2:42 PM Page 11

INTRODUCTION 11

Cam
Turret

Cam

(a) Oscillating (b) Indexing turret,
follower. tapered roller.
FIGURE 1.14. Cylindrical blade cam.

(a) Convex cam. (b) Concave cam.
FIGURE 1.15. Globoidal cam-groove type, oscillating follower.

indexing globoidal cam with a turret follower. These blade-type globoidal indexing cams
have high accuracy, long life, low vibration, low noise, and shockless performance under
high speeds. For best action, the bearings should be preloaded so that the system has
limited backlash. This cam and the follower can be obtained commercially. For indexing,
they are often substituted for the familiar Geneva and star-wheel mechanisms, which have
inherently poor high-speed dynamic properties.
The conical cam shown in Figure 1.17 has the shape of a cone driving the follower in
a plane perpendicular to the base of the cone. The follower translates or oscillates, whereas
the cam usually rotates. This cam is used infrequently because of its cost and the diffi-
culty in cutting its contour. However, a conical cam may be necessary to change the direc-
tion of motion in a limited space. Grooves have been cut into conical cams for the
positive-drive action of the follower.