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 centre of the Cam-Shaft and the contact-point between the Cam and the Cam-Roller.


Plot the Cam Radii of Curvature with a Graph:

Design-Set-7-012

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

The Cam Display and Properties dialog should be open.

2.Click Cam Display and Properties dialog-box > Display tab > Cam Visibilities >

You can see you can display: Cam 1, the Pitch-Curve, and / or Cam 2.

We need to know if Cam 1 or Cam 2 is the smaller cam.

The Cam # is next to the contact-point between the Cam and the Cam-Roller - it is a number 1 or 2.

In this case, next to the smaller cam there is the number 2.

3.Click Cam Display and Properties dialog-box > Display tab > Cam Visibilities >Cam 1.

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

Icon-FB-CamData

1.Mechanism-Editor: Click Kinematic FB toolbar > Add Cam-Data FB, then click the graphic-area.

Icon-FB-Graphs

2.Mechanism-Editor: Click Kinematic FB toolbar > Add Graph FB, then click the graphic-area.

We need to link the 2D-Cam in the model with the Cam-Data FB.

3.Mechanism-Editor: Edit the Cam-Data FB to open the Cam-Data Dialog-box (or see How to open a Dialog-Box)
4.Mechanism-Editor: Click the 2D-Cam in the graphic-area (or Assembly-Tree), Click OK-tiny-11-15 to close the Cam-Data FB

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

5.Mechanism-Editor: Connect the Radius-of-Curvature output-connector(3) of the Cam-Data FB to the Y1 input-connector of the Graph FB.
6.Mechanism-Editor: Connect the Pressure-Angle output-connector(4) of the Cam-Data FB to the Y2 input-connector of the Graph FB.

Design-Set-7-011

STEP 3: Make sure the plot of the Radius-of-Curvature is for Cam 2 (Note: the default is Cam 1)
1.Double-click the Graph FB icon in the graphic-area (or see How to open a Dialog-Box)

The Graph is now open.


Note:

Each wire has up to 3 data-channels. We can plot one data-channel with each wire we connect to an input-connector of the Graph FB.

To select which data channel we plot, we use the Y-input: Cam-Data drop-down to the right of the plot area in the open Graph.

We need to select Radius-of-Curvature 2 for Cam 2.


2.Click Graph > Y-input data-channel > Radius-of-Curvature 2Red-14-1b

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STEP 5: Edit the Minimum and Maximum Scales for each Plot.

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.

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1.Click : Graph toolbar > Graph-Settings

Set the Maximum and Minimum Radius of Curvature Plot

1.Graph-Settings > Title and Input Selection  > Y1 : Rad of Curvature2 (enter a Graph Title if you want)
2.Graph-Settings >  Y-axis   : De-select Auto-scale
3.Graph-Settings >  Y-axis   : Y maximum = 200 ; Y minimum = 0

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 (update again later as Pressure Angle improves)

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 larger range, and reduce it when the Pressure-Angle improves.


7.Close the Graph-Settings dialog.

Save your model

Design-Set-7-015

Tutorials and Reference Help Files for MechDesigner and MotionDesigner 14.2 + © Machine, Cam, Mechanism, and Motion Design Software by PSMotion Ltd