Page 171 - Cam Design Handbook

THB6 8/15/03 2:40 PM Page 159

CHAPTER 6

ELEMENTS OF CAM
PROFILE GEOMETRY

Harold A. Rothbart, D.Eng.

6.1 INTRODUCTION 160 6.4 CAM RADIUS OF CURVATURE 169
6.2 CAM PROFILE GRAPHICAL LAYOUT 160 6.4.1 Radius of Curvature 169
6.3 CAM PRESSURE ANGLE 162 6.4.2 Undercutting of Cam—Roller
6.3.1 Introduction 162 Follower 170
6.3.2 Pressure Angle Forces— 6.4.3 Undercutting of Cam—
Translating Roller Follower 163 Flat-Faced Follower 173
6.3.3 Pressure Angle Forces— 6.4.4 Hub Design 173
Oscillating, Roller Follower 166 6.5 SUMMARY 174
6.3.4 Pressure Angle Forces—
Translating Flat-Faced
Follower 168

SYMBOLS

A = follower overhang, in
B = follower bearing length, in
d h = hub diameter, in
d s = shaft diameter, in
F = force normal to cam profile, lb
l = distance from force F n to follower axis, in
L o = external load on follower
N 1N 2 = forces normal to follower stem, lb
Q oQ b = reactions at pivot point Q, in
r = radius to cutter center. in
r b = base circle radius, in
R g = cutter or grinder radius, in
R r = roller follower radius, in
s = follower rise, in (other chapters usually shown as y)
T = total torque on system, lb/in
W = radius of follower stem, in
a = pressure angle, deg
a m = maximum pressure angle, deg
c = angle for radius r, rad
k = distance from normal force F n to pivot point Q, in
m = coefficient of friction
m c = coefficient of friction between cam and flat-faced follower
r = radius of curvature, in
r c = radius of curvature of cam profile, in
r k = radius of curvature of pivot curve, in
q = cam angle for rise, s, rad

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