Page 297 - Cam Design Handbook
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THB10 9/19/03 7:28 PM Page 285
CHAPTER 10
CAM MANUFACTURING
Harold A. Rothbart, D. Eng.
10.1 MANUFACTURING METHODS 285 10.5 CAM SHAPES VERSUS ACCELERATION
10.2 MASTER CAM ANALOG CURVE 296
DUPLICATION CAMS 287 10.6 DYNAMIC ERRORS BY FINITE
10.3 CONTINUOUS NUMERICAL DIFFERENCES 297
CONTROL (CNC) CAMS 288 10.7 MATERIAL PROCESSES 301
10.4 MANUFACTURING ERRORS AND 10.7.1 Melting Practice 302
DISCUSSION 291 10.7.2 Heat Treatment 302
10.4.1 Structural Errors 293 10.7.3 Metalworking 302
10.4.2 Fixed Backlash Errors 293 10.8 SPARE PARTS LISTING 303
10.4.3 Variable Backlash Errors 293 10.9 CAM FOLLOWERS 305
10.4.4 Miscellaneous Errors 293 10.9.1 Roller Followers 305
10.4.5 Probabilistic Model of Cam 10.9.2 Roller-Follower Installations 306
Profile 294 10.9.3 Sliding Followers 312
10.4.6 Manufacturing Discussion 295 10.10 CONCLUSION 312
SYMBOLS
r c = distance from center to cam, in
y = follower displacement, in
y ¨ = follower acceleration, in/sec 2
y ¨ m = maximum follower acceleration, in/sec 2
y ¨ s = follower deviation from theoretical cam curve, in
F = normal force, lb
I = moment of inertia of roller, lb-in-sec 2
R c = radius of cutter or grinder, in
R r = roller radius, in
a = angular acceleration of roller, rad/sec 2
m s = static coefficient of friction between cam and roller
s = error or deviation from theoretical cam profile, in
q = increment angle, rad
w = cam speed, rad/sec
10.1 MANUFACTURING METHODS
It is important that engineers be aware of the fabrication techniques involved in
manufacturing and inspecting the actual cam produced from the design information. They
should be knowledgeable about the experience and level of dedication of the machine shop
workers in making and assembling the parts. To ensure quality (1) errors in fabrication
and misalignment in assembly should be eliminated; (2) cam fabrication should be use-
fully monitored, and (3) tool wear, vibrations, and chatter should be eliminated. Neces-
sary periodic inspection also should be minimized.
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