ILLUSTRATED SOURCE BOOK of MECHANICAL COMPONENTS
SECTION 18
CAMS
Generating Cam Curves
18-2
Balance Grooved Cams
18-9
Computer and N/C Simplifies Cam Design
18-15
Theory of Envelopes: Cam Design Equations
18-18
Cams and Gears Team Up in Programmed Motion
18-28
Minimum Cam Size
18-30
Spherical Cams: Linking Up Shafts
18-38
Tailored Cycloid Cams
18-4 1
Modifications & Uses for Basic Types of Cams
18-45
18-2
Generating Cam Curves
It usually doesn’t pay to design a complex cam curve if it can‘t be easily
machined-so check these mechanisms before starting your cam design.
Preben W. Jensen
F you have to machine a cam curve into the metal
I blank without using a master cam, how accurate
can you expect it to be? That depends primarily on
how precisely the mechanism you use can feed the
cutter into the cam blank. The mechanisms described
here have been carefully selected for their practicabil-
ity. They can be employed directly to machine the
cams, or to make master cams for producing othcrs.
The cam curves are those frequently employed in
automatic-feed mechanisms and screw machines. They
are the circular, constant-velocity, simple-harmonic,
cycloidal, modified cycloidal, and circular-arc can1
curve, presented in that order.
Circular cams
This is popular among machinists because of the
ease in cutting the groove. The cam (Fig 1A) has a
circular groove whose center, A, is displaced a dis-
tance a from the cam-plate center, Ao, or it may sim-
ply be a plate cam with a spring-loaded follower (Fig
1B).
Interestingly, with this cam you can easily duplicate
the motion of a four-bar linkage (Fig IC). Rocker
BBo in Fig lC, therefore, is equivalent to the motion of
the swinging follower in Fig IA.
The cam is machined by mounting the plate ec-
centrically on a lalthe. The circular groove thus can
be cut to close tolerances with an excellent surface
finish.
If the cam is to operate at low speeds you can re-
place the roller with an arc-formed slide. This per-
mits the transmis