Pitch Circle Problem 8.17 Construct the profile of a disk cam that ...
Pitch Circle Problem 8.17 Construct the profile of a disk cam that ...
Pitch Circle Problem 8.17 Construct the profile of a disk cam that ...
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
320.000 11.200<br />
340.000 2.800<br />
360.000 0.000<br />
To lay out <strong>the</strong> <strong>cam</strong>, first draw <strong>the</strong> prime circle which has a radius <strong>of</strong> 2.0" + 1.0" = 3.0". Next draw<br />
<strong>the</strong> pivot circle for <strong>the</strong> follower pivot. The radius <strong>of</strong> <strong>the</strong> pivot circle is 4". Draw <strong>the</strong> follower in <strong>the</strong><br />
initial position ( = 0˚ ) to determine <strong>the</strong> follower length (r 3 ) and <strong>the</strong> position on <strong>the</strong> pivot circle<br />
corresponding to = 0˚ . As indicated in Example 8.5, <strong>the</strong> length r 3 is given by<br />
r3 = r 1 2 (rb +r0) = 4 2 (2 +1) 2 = 2.646"<br />
Identify <strong>the</strong> point on <strong>the</strong> pivot circle corresponding to = 0˚ , lay <strong>of</strong>f <strong>the</strong> radial lines at 20˚<br />
increments from this point, and label <strong>the</strong> lines in <strong>the</strong> counterclockwise direction. Draw lines from<br />
<strong>the</strong> intersections <strong>of</strong> <strong>the</strong> radal lines with <strong>the</strong> pivot circle tangent to <strong>the</strong> prime circle. Then lay <strong>of</strong>f <strong>the</strong><br />
angular displacements from <strong>the</strong>se tangent lines. Locate <strong>the</strong> center <strong>of</strong> <strong>the</strong> follower by <strong>the</strong> distance r 3<br />
from <strong>the</strong> pivot circle along <strong>the</strong>se lines. Draw 1" radius circles through <strong>the</strong> endponts <strong>of</strong> <strong>the</strong> distances<br />
layed <strong>of</strong>f along <strong>the</strong>se lines, and fit a smooth curve which is tangent to <strong>the</strong> circles corresponding to<br />
<strong>the</strong> roller follower.<br />
The <strong>cam</strong> <strong>pr<strong>of</strong>ile</strong> is shown in <strong>the</strong> following figure.<br />
- 369 -