Page 72 - Cam Design Handbook

THB3 8/15/03 12:58 PM Page 60

60 CAM DESIGN HANDBOOK

Substituting gives

1 1
At + v t + V t + A t = 4.
2
2
2 11 T 2 Q 3 2 3 3
Again substituting,
1 1
At + At t + At t - At = 4
2
2
2 11 1 1 2 1 13 3 13
1 2 1 2
A ( 00222) +. A ( 00222 00167)+. )( . A ( 00222 00333) -. )( . A ( 00333) =. 4.
2 1 1 1 3 1
Thus
A = 4050 in sec 2
1
A =- 2700 in sec 2
3
The velocity at the points of intersection from Fig. 3.3 is
v = v = A t = (4050 )(0 0222. ) = 90 ips.
T Q 11
The displacements for each part are
1 1
2
2
y A t = ( 4050 0 0222) = in
)( .
1
1 1 1
2 2
yA t t = ( 4050 0 0222 0 0167) =. )( . 1 5 . in
)(
2 1 1 2
y = . in
15
3
We can now plot the curves of displacement, velocity, and acceleration as shown in
Fig. 3.3.

Velocity
90 ips
Acceleration
4050 in/sec 2

-2700 in/sec 2

FIGURE 3.3. Example modified constant velocity curve.