Machinery's Handbook, 31st Edition
2384
CAMS AND CAM DESIGN
2
a e N 2 6 ! φ ∆ = ∆ c m
(21)
where Δ a = change in acceleration, e = error in inches, Δ φ = w idth of error in degrees. The plus (+) sign is used for a “bump” and the minus ( − ) sign for a dent or hollow in the surface For e = 0.001, Δφ = 1 ° , and N = 900 rpm, . a 2 0001 1 6 900 58320 in/sec 2 2 × × ° ∆ =+ = a k which is 10 times the acceleration calculated for a perfect cam and would cause sufficient force F n to damage the cam surface. On high speed cams, therefore, accuracy is of consid erable importance. (e) What is the cam torque at φ = 45 ° ? From Formula (20),
. 1 56 0 4 110 30 108 in.-lbs. min . sin n # # ° = + = + ^ ^ = h T R y F h o sin α
(f) What is the radius of curvature at φ = 45 ° ? From Formula (10),
2 2 3
dr
r
2
r r R y 2 d = + = + = c c m c m m ; E dr r d d r 2 d 2 min 2 2 ρ φ φ φ = + − +
. 156 04 196 . .
From Formula (13b),
360
h 180 1 °
100 180 1 1 # # ° ° π :
100 360 45 # ° °
dr
°
φ
°
cos
cos
a
k
;
E
c
m
D
=
−
=
−
d
φ πβ
β
. 112
=
From Formula (13c),
360
h 2 180 2 ° ^ h
100 2 180 1 2 2 # # # ° ° π ^ ^ h h
100 360 45 # ° °
d d r 2 φ
φ
°
°
sin
sin
a
k
c
m
=
=
2
2
β
πβ
. 064 196 2 112 196 064 196 112 . . . . . . 2 6 2 2 2 2 3 @ # + − + ^ ^ ^ ^ h h h h
=
. 226in.
=
ρ
=
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online