2D-Cam Elements

2D-Cams have a number of elements, function-blocks and dialog-boxes that relate to each other. The Action [in the table ] shows how they are related and when to use them.

hmtoggle_plus12D-Cam : Related Elements and Actions

Action 1A

Add 2D-Cam

... optional ...

 

Action 1B

Edit 2D-Cam dialog-box

Action 2A                

Add Cam-Data FB

Action 2B

Edit Cam-Data FB to select a 2D-Cam

Action 3A

Do Cam-Analysis [with Graph FB]

Action 3B

Calculate Cam-Coordinates

*Force analysis only: Configure Power Source

Add Cam-Data Function-Block (FB)

Toolbar :

Kinematics FB toolbar

Add CamData FB

Cam-Data FB

Menu :

Add menu > Add Cam-Data FB

What for :

To analyse a 2D-cam - see below: Cam Analysis

To calculate the coordinates of a 2D-cam

See also: Add 2D-Cam

Cam-Data FB in Graphic-Area

Cam-Data FB in Graphic-Area

STEP 1: Add the Cam-Data FB to the graphic area
1.Click Kinematics Function-Block toolbar > Add Cam-Data FB
2.Click in the graphic-area

The Cam-Data FB is now in the graphic-area - see left.

Double-click FB to open the dialog-box

STEP 2: Edit the Cam-Data FB to open the Cam-Coordinates dialog-box
1.Double-click the Cam-Data FB to open the Cam-Coordinates dialog-box

- or -

Cam-Coordinates dialog-box opens immediately.

You must now select a 2D-Cam to link it to the Cam-Data FB.

Dialog-CamCoordiantes-Open

MD-2DCam-Element-GA-1click

STEP 3: Link a 2D-Cam to the Cam-Coordinates dialog-box
1.Click a 2D-Cam in the graphic-area

The 2D-Cam becomes linked to the Cam-Data FB . It is the: Selected Cam-Track.

Dialog-CamCoordiantes-Selected

STEP 4: Calculate the Cam-Coordinates NOW
1.Use the buttons in the toolbar to calculate and save Cam-Coordinates.

See Cam-Coordinates dialog-box

OR

STEP 3: Do Cam-Analysis NOW
1.Click  to close the Cam Coordinates dialog
2.Do Cam-Analysis with the data that is available at the 5 output-connectors of the Cam-Data FB

See below : Cam Analysis Parameters

tog_minusCam Analysis Parameters

GA-FB-CamData

The five output-connectors from the Cam-Data FB provide:

F   :  Contact Force : See Note 1
Ԏ  :  Contact Maximum Shear Stress : See Note 2
ρ  :  Radius-of-Curvature : See Note 3
μ  :  Pressure Angle : See Note 4
Ue : Entrainment Velocity - see Note 5

Drag wires from the output-connectors of the Cam-Data FB to a Graph FB or a Statistics FB

In the Graph FB, make sure you select the correct cam [Cam 1 or Cam 2] in the Y–axis display option.


Top-Tip:

When there is more than one 2D-Cam in the model, it frequently best to add one Cam-Data FB and Graph FB for each 2D-Cam in your model.

Connect the same output-connector from each Cam-Data FBs to the same Graph FB.

Then, it is easier to compare simultaneously the same analysis parameter [e.g. Pressure-Angle] of up to four 2D-Cams in one graph plot.


Make sure to do Configure the Power Source.

Note 1:

If Force does not show in the Graph FB, even with the Power Source configured correctly, try the changing the Cam: Cam 1 or Cam 2.

Note 2:

If Shear-Stress does not show in the Graph FB, even with the Power Source Configured Correctly, try the changing the Cam: Cam 1 or Cam 2.

The Maximum Shear Stress happens to be below the Cam Surface. You must enter the correct material properties for the Cam and the Cam-Follower in the 2D-Cam dialog-box.

The calculations we use to calculate the Maximum Shear Stress have assumptions. The most significant assumption is that there is no lubrication, but that there is no friction between the Cam and the Cam-Follower.


Note 3:

The Radius-of-Curvature [ROC] of the Cam-Follower is assumed to be 'positive'. If the cam conforms to the cam-follower roller [wraps around], the cam has a 'negative' ROC. If the cam is convex to the cam-follower roller, the cam has a 'positive' ROC.

Radius-of-Curvature of the Pitch-Curve is not available. If you need to know the Radius-of-Curvature of the Pitch-Curve, export the Radius-of-Curvature of Cam 1 and Cam 2 to Excel, and calculate their average. Also, it is easy to forget which cam is in the Graph plot. Make sure you use the Y–axis Display drop-down box to select the correct Cam.


Note 4:

1.The Pressure Angle is through the Centre of the Cam-Follower. There are also two other Pressure Angles available: the Contact Pressure Angle of Cam 1 and Cam 2.
2.We cannot calculate Pressure Angle for a Stationary Cam. As a work-around, add a line to the Cam-Follower that is perpendicular to the movement of the Cam-Follower. Add an 'Angle' measurement with the Cam Contact Point and the Line that gives the motion direction of Cam-Follower Roller. Please email for more information.

Note 5:

You need Entrainment Velocity to calculate the Film Thickness of the Lubrication between the Cam-Follower and Cam. If you know the surface finish of the cam and cam-follower, then you can also calculate the Film Thickness Ratio. This is an important parameter to calculate as it strongly influences the life of the cam and follower.

tog_minusCam Contact-Force / Contact-Stress

See also : Conjugate Cams FB


There are four ways to show and plot the Contact-Force between the Cam and the Cam-Follower.

In all four cases, you must do Configure Power Source to calculate Contact-Force and Contact Shear-Stress correctly.

Display in the Graphic-Area:

1.Display Force Vectors button. This shows two equal and opposite vectors:
the force vector that ACTS-ON the Cam-follower Part, and
the force vector that ACTS-ON the Cam-Part.

You must analyse whether the force between the cam and the follower is active or not.

2.Use: 2D-Cam dialog-box  > Cam Display Options > Contact-Force.
The Force remains at zero when the active force is less than zero.

Use a Graph-FB:

3.Use a Force-Data FB, select the Cam as the Force element, plot with a Graph FB.

You must analyse whether the force between the cam and the follower is active or not.

The Force is always 'positive'.

4.Use the Cam-Data FB and the Contact Force output-connector to plot with a Graph FB.

Contact-Force is = '0' if Contact-Force '0'.

This is the preferred option if you need to know whether the Cam-Force becomes less than zero.

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