Machinery's Handbook, 31st Edition
2376
CAMS AND CAM DESIGN
R 0
R max
E 2 L f
k tan τ 2
R y 2
M
h
R y 1
y 2
k tan τ 1
α 2
R u
E 1 α ” 1 α 1
y 1
O 1
O 2
R min
A Fig. 18. Finding Proportions of Cam; Swinging Roller Follower (CCW Rotation)
R 0
L f
k tan τ 2
y 2
R y 2
M
E 2
k tan τ 1
h
y 1
α 2
E 1
R y 1
α 1
R u
α ” 1
R min
R
max
O 1
O 2
A
Fig. 19. Finding Proportions of Cam; Swinging Roller Follower (CW Rotation)
Fig. 19 shows the construction for rotation toward pivot point M (clockwise rotation of the cam in this case). The layout of the cam curve is made in a manner similar to that shown previously in Fig. 12. In this example, the cam mechanism was so proportioned that the pressure angles at cer tain points (corresponding to P 1 and P 2 ) do not exceed certain specified values (namely α 1 and α 2 ). To make sure that the pressure angle at no point along the cam profile exceeds the speci fied value, the previous procedure should be repeated for a series of points along the profile. Formulas for Calculating Pressure Angles.— The graphical methods described previ ously are useful because they permit layout and measurement of pressure angles and radii of curvature of any cam profile. For cams of complicated profiles, and especially if
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