Getting Started Tutorials - MechDesigner > Tutorial 7: Design-Sets

Edit the Design-Set.

The objectives are to edit the four dimensions in the Design-Set, and

•Make sure the maximum radius of the smaller cam does not exceed :

•Minimize the Pressure-Angle

We will use a Cam-Data FB and a Graph FB to plot the Pressure Angle and the Radius-of-Curvature* to find the maximum radius of the Cam.

Note: * We could also use a Measurement FB to measure between the the center of the Cam-Shaft and the contact-point between the Cam and the Cam-Roller.

Plot the Cam RadUS of Curvature with a Graph:

STEP 1: Edit the 2D-Cam to display only the Inner cam.

1.Mechanism-Editor: Double-click the 2D-Cam in the graphic-area (or see How to open a dialog-box )

The 2D-Cam dialog is be open.

The two Cams are labelled as Inner, Outer

3.Click 2D-Cam dialog-box > Display tab > Cam Visibilities >Inner

4.Click to close the 2D-Cam dialog-box.

STEP 2: Add a Cam-Data FB and Graph FB to the graphic-area

1.Mechanism-Editor: Click Kinematic FB toolbar > Add Cam-Data FB

2.Click the graphic-area

3.Mechanism-Editor: Click Kinematic FB toolbar > Add Graph FB

4.Click the graphic-area.

A Cam-Data FB and a Graph FB are now in the graphic-area.

STEP 3: Link the 2D-Cam in the model with the Cam-Data FB

1.Mechanism-Editor: Edit the Cam-Data FB to open the Cam-Data Dialog-box (or see How to open a Dialog-Box)

We need to select the 2D-Cam

2.Mechanism-Editor: Click the 2D-Cam in the graphic-area (or Assembly-Tree),

3.Click to close the Cam-Data FB

The 2D-Cam is now linked to the Cam-Data FB.

STEP 4: Connect wires from the Cam-Data FB to the Graph FB (see image above)

1.Mechanism-Editor: Connect a wire from the Radius-of-Curvature output-connector(3) of the Cam-Data FB to the Y1 input-connector of the Graph FB.

2.Mechanism-Editor: Connect a wire from the Pressure-Angle output-connector(4) of the Cam-Data FB to the Y2 input-connector of the Graph FB.

Y-Axis Data Channel

We need to make sure we are looking at the Radius of Curvature of the Inside Cam in the plot.

STEP 5: In the Graph interface, select Inside RoC (see image above)

1.Mechanism-Editor: Double-click the Graph FB icon in the graphic-area (or see How to open a Dialog-Box)

The Graph FB interface is now open.

2.Graph FB interface: Click Graph interface > Y1: Cam Data drop-down (see image above)

3.Graph FB interface Click INSIDE RoC

Notes:

The Y-axis scale for the Radius-of-Curvature can have a massive range - from plus to minus infinity.

It is easier to use the plot if we set the Minimum and Maximum values of each Y-input with the Graph-Settings

STEP 6: Open the Graph-Settings dialog

1.Click : Graph toolbar > Graph-Settings

STEP 7: Edit the Minimum and Maximum Scales for each Plot.

1.Graph-Settings > Title and Input Selection > Y1 : Inside ROC Red-14-2

2.Graph-Settings > Y-axis : De-select Auto-scale Red-14-3

3.Graph-Settings > Y-axis : Y maximum = 200 ; Y minimum = 0 Red-14-4

Set the Maximum and Minimum Pressure-Angle

4.Graph-Settings > Title and Input Selection > Y2 : Pressure-Angle

5.Graph-Settings > Y-axis : De-select Auto-scale

6.Graph-Settings > Y-axis : Y maximum = 60 ; Y minimum = -60 (edit again to ±40 as the Pressure Angle improves)

7.Close the Graph-Settings dialog.

Note:

I would normally set the maximum and minimum Pressure-Angle values to ±35.

However, the Pressure-Angle is very biased to a large negative value. Hence, we can set a large range, and reduce it as the Pressure-Angle improves.

Step 7.3: Add Cam-Data and Graph FB

Step 7.3: Add Cam-Data and Graph FB

Edit the Design-Set.

Plot the Cam RadUS of Curvature with a Graph: