In this tutorial a plate cam with an oscillating, or swinging arm follower will be designed.   See the tutorial for the Kinematics here.

PROBLEM: 

          Design a cam to drive the slide shown in the drawing below to place a part in an assembly (not shown).  This slide is to move in 0.75 in (19.05 mm) and then retract without pause.  At the forward stroke, there is force for of 1.5 lbf on the slide to place the part.  This occurs over a distance of 0.125 in (3.175 mm).  This only occurs on the forward stroke. The cycle rate is 120 parts per minute, or 7200 per hour.  There is to be a pause at the retract position of 0.05 sec.  

The question here is: how do we turn these requirements into a timing chart and thereby data to enter into Cam Designer SE?

1.  The cycle rate tells us that the cam must rotate at 120 rev/min (one cycle for each rotation of the cam).  Then the degrees of cam rotation per second will be = 120 rev/min*360 deg/rev*1 min/60 sec =720 deg/sec.

2.  Therefore, the angle the cam will rotate through in 0.05 sec is: 720 deg/sec* 0.05 sec=36 deg.

3.  Since we need the slide to move in and back we will make the forward and return strokes equal.  This can be changed later, but this is a good start.  The remainder of the 360 degrees is 324 degrees and divided by 2= 162 deg

The next thing to be determined is: what is the relationship between the distance the slide moves and the angle the follower moves.  There are two ways to determine this: 

          a.  First way if you have the slide modeled in your CAD system is to measure it.

          b.  Second way is to compute it with simple trigonometry. 

Timing Chart:

          The timing chart for the motion above will look like this:

Some observations of this chart:

1.  All we are doing here is to define the stroke and it's relation to the rotation of the cam.  The motion profile will be defined in Cam Designer SE.

2.  The dwell of 36 degrees is placed at the end of the return stroke, but could be at the start. 

The mass of the slide is 0.285 lbm.  Cam Designer SE requires that the inertia of an oscillating follower be reflected to the pivot.  This requires using the parallel axis theorem.  The mass of the slide will be reflected to the pivot, as well as the moment of inertia of the arm.  The easiest way to compute the inertia of the arm and slide is to use the CAD system to compute the mass of the slide and the inertia of the arm.  The CAD system will likely compute the mass moment of inertia about the center of gravity of the arm.  For Cam Designer SE, that moment of inertia must be "transfered" to the pivot.  The equation is:  The complete equation for the inertia of the arm and the slide is:

In this example the following

I_CG=0.341202 lbm*in²

m_arm=0.195202 lbm

d_CG=0.991 in

m_slide=0.285901 lbm

l_lever=2.5 in

Using this data the inertia at the pivot is computed as: I_pivot=2.31973 lbm*in²

Cam Designer SE

Now open Cam Designer SE.  At the main screen there will be not kinematics or geometry.  Click on the Kinematics button and the and the screen appear as below.  Since we need to move in and back and there is no requirements for the velocity, acceleration or jerk, we are just going to select the rise return for the motion.  However, before we enter any kinematics profile, we need to select the cam type and follower type.  That has been done in the screen below.

Kinematics:

The screen below shows the completion of the kinematics.  The Kinematics and Geometry has been undocked to show this.  Also notice that the segment data and graph has been chosen to view this.  Try the other choices. 

The main screen will appear as below.  Notice that the cam is Unnamed as well as the Kin.  That is because the kinematics has not been stored.  When the kinematics is saved to disc, the name of the cam will be the same name as the Kinematics. 

After saving the Kinematics:

We could try different profiles here to see if the performance would be better, but, for moving in and back, the Rise-Return is the best, since it matches velocity, acceleration and jerk at the turn around point.

Geometry:

Click the Geometry Button in the main screen and the Geometry form will appear.  You can only see this after the first profile has been entered and saved in Kinematics.  See the tutorial video for the Geometry here.

Now select Plt for plate cam and in the Followers drop down select Oscillating-roller, then select Rib in the Face or Groove section and the form will appear as below:  Notice that the remainder of the data has also been entered.  Also, the drawing of the cam is shown.  After a few tries, the best

You can now examine the output data to determine if this is going to be satisfactory for this design.  Once that is done, the cam curves can be exported via DXF, or Surface Curve Vectors.  For these options see Export Options

Make sure you save the cam before you close Cam Designer SE.  Right click in the Cam list in the main screen and select Save Cam As, give it a name and the name will change in the Cam list to what you saved it as.

This completes this tutorial.