Dialog: Cam-Data FB

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Dialog: Cam-Data FB

Cam-Data FB > Cam-Analysis

To analyze a 2D-Cam:

Action

Step in this topic:

1.Add a Cam-Data FB

see STEP 1

2.Link the Cam-Data FB to a 2D-Cam

see STEP 2

3.Connect wires to a Graph FB

see STEP 3

STEP 1: Add Cam-Data FB

To add a Cam-Data FB to the graphics-area:

Add Motion FB

1.Click Kinematics FB toolbar > Cam-Data FB

or

1.Click Function-Blocks menu > Cam-Data (FB)

2.Click the graphics-area

The Cam-Data FB is now in the graphics-area and Assembly-Tree.

Note:

Typically, add a CAM-Data FB for each 2D-Cam in your model.

TOP-TIP - if there is more than one 2D-Cam in your model

1.Edit the color of each 2D-Cam in your model

2.Rename the element-name of the 2D-Cam to its color

3.AND, rename element-name of each CAM-Data FB that you link to a 2D-Cam to the same color as the 2D-Cam.

See also: Application-Settings>Graphics>Display-Options>Enable “Show Function-Block names”

STEP 2: Link the Cam-Data FB to a 2D-Cam

To link the Cam-Data FB to a 2D-Cam, you must first open the Cam-Data dialog.

To open the Cam-Data dialog:

Double-click FB to open the dialog-box

1.Double-click the Cam-Data FB

OR

1.See How to open a dialog

The Cam-Data dialog is now open - see image below.

You can see that the name of a 2D-Cam element is not in the Selected 2D-Cam is boxRed-14-1.

Also, see the message “Select a Cam to activate this form”.
Cam-Data dialog - No 2D-Cam

Cam-Data dialog - 2D-Cam ''Not Seleted''
Click to select a 2D-Cam

Click to select a 2D-Cam

To select a 2D-Cam:

2.Click a 2D-Cam in the graphics-area or the Assembly-Tree

The 2D-Cam is now in the Selected 2D-Cam is box - see Red-14-1 in image below.

3.Click Red-14-2 () to close the Cam-Data dialog,

or

3.See Calculate Cam-Coordinates

Cam-Data FB : The name of the selected 2D-Cam is "Blue".

Cam-Data FB : The name of the selected 2D-Cam is "Blue".
MD-FB-CAMDATA-1

Result:

In the graphics-area, the caption above the Cam-Data FB has two parts:

•Top (Inner in the example): the last calculated Flank of the 2D-Cam that you have selected.

•Bottom Line (Blue in the example): the element-name of the Cam-Data FB - see TOP-TIP

You can:

•Analyze 5 Cam parameters - see Cam-Analysis Parameters

•Calculate the Cam's Coordinates - see Cam-Coordinates dialog

TOP-TIP:

If you have many 2D-Cams in your model, you can make it easier to see which Cam-Data FB is linked with which 2D-Cam.

1.Edit the color of a 2D-Cam - see 2D-Cam dialog : Display tab >  Display Option 

2.AND rename the 2D-Cam to the color of the 2D-Cam - see Rename element

3.AND rename the Cam-Data FB that has a link with a 2D-Cam, to the color of the 2D-Cam

Now, it is easier to see in the graphics-area and the Assembly-Tree, the link between 2D-Cams and Cam-Data FBs

STEP 3: Connect wires to a Graph FB

Analysis Parameters from Cam-Data FB

Analysis Parameters from Cam-Data FB

The output-connectors from the Cam-Data FB provide over a machine-cycle:

•F  : Contact Force : see Note 1

•Ԏ : Maximum Contact Shear-Stress : See Note 2

•ρ : Radius-of-Curvature : see Note 3

•μ : Pressure Angle : see Note 4

•Ue : Sliding Velocity : see Note 5

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

Make sure you select the correct Cam-Profile (Inner, Outer, or Pitch-Center Path) in the Y–axis display option of the Graph FB interface.

Note 1: Contact-Force

Configure the Power Source before you analyze the Contact-Force.

If, in a Graph FB, the Contact-Force is for a machine-cycle, and the Configure Power Source is correct, change the Graph FB > Y-axis Data-Channels from Inner to Outer, or vice versa.

Note 2: Maximum Contact Shear-Stress

Configure the Power Source before you analyze the Maximum Shear-Stress.

If in a Graph FB, the Shear-Stress is for a machine-cycle, and the Configure Power Source is correct, change the Graph FB > Y-axis Options from Inner to Outer, or vice versa.

About Maximum Contact Shear-Stress

The Maximum Shear Stress is not at the surface of the Cam-Profile - it is a little below its surface. The depth below the surface is a function of the material properties and shapes of the contacting bodies, and the Contact-Force.

To calculate Maximum Contact Shear-Stress, we assume that friction is zero and the Cam-Profile and Follower Profile are perfectly smooth.

Also, we assume that the material properties of the Cam-Profile and the Follower-Profile are:

•Young's Modulus,

•Poisson's Ratio,

Or, if you calculate the Life of the Roller and Cam, we take the properties from the Steel Category in 2D-Cam dialog > Cam-Life tab.

In the Cam-Life tab, we calculate the Maximum Contact-Stress, Maximum Shear-Stress, and the Depth of the Maximum Shear-Stress.

Note 3: Radius-of-Curvature

By convention, the Radius-of-Curvature (RoC) of a Follower-Roller is positive.

When the cam is convex relative to the Roller, the RoC of the cam is positive.

When the cam is concave relative to the Roller, the RoC of the cam is negative.

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 the Inner and Outer cams to Excel, and calculate the average.

Note 4: Pressure Angle

The Pressure Angle is through the center of the Follower-Roller. There are two other Pressure Angles, which are the Contact Pressure Angle of the Inner and Outer Cams - these are labeled as Inside Cont. PR, Ang and outside Cont. PR, Ang in the Graph FB > Y-axis display options.

Use Contact Pressure Angle with Flat-Faced Follower-Profiles.

We do not calculate for you the Pressure Angle of a Stationary Cam.

Note 5: Sliding-Velocity

The Sliding-Velocity assumes the Follower-Profile does not roll, even if the Profile represents a Roller; it assumes it slides over the Cam-Profile. Use the Sliding-Velocity to calculate the Film Thickness of the lubricating oil between the Follower-Profile and Cam-Profile. If you know the surface finish of the Cam-Profile and the Follower-Profile, you can also calculate the Film Thickness Ratio, . This is an important parameter as it strongly influences the life of the cam. A Film Thickness Ratio of less than 1 means that metal asperities of the Follower-Profile and Cam-Profile contact each other, and wear occurs.

Sliding Velocity = (Velocity of Cam-Profile – Velocity of Follower-Profile)

Entrainment Velocity = (Velocity of Cam-Profile +Velocity of Follower-Profile) ÷ 2

Slip-Slide-Ratio = Sliding-Velocity ÷ Entrainment Velocity

Top-Tip:

To plot and compare the Pressure-Angle for up to 4 × 2D-Cams:

1.Add 4 × Cam-Data FBs and 1 × Graph FB to the graphics-area.

2.Link the Cam-Data Fbs to 4 × 2D-Cams

3.Connect a wire from the Pressure-Angle output-connector of the 4 × Cam-Data FBs to the 4 × Y-axis input-connectors of the 1 × Graph FB

Now, in the Graph FB, set the scale of the Y-axes to the same minimum and maximum values. Do this:

4.In the Graph Settings > Title and Input Selection > Y-axis Input drop-down, select Set all

In the Graph-Settings >  Y-axis 

5.Deselect Auto-scale Y-axis

6.Enter 'soft-limits' for Y-maximum and Y-Minimum - e.g. for Pressure Angle, enter  +30º and –30º respectively.

Now, it easier to compare the Pressure-Angles of all 4 × 2D-Cams, and to see if the Pressure-Angle of a 2D-Cam is greater-than Y-Maximum and/or less-than the Y-Minimum values.
tog_minusContact Force / Contact Shear-Stress

After you correctly Configure the Power Source, you can find the Contact-Force and Contact Maximum Shear-Stress between the Cam-Profile and the Follower-Roller.

There are four methods to

Display in the graphics-area:

Method 1: Forces toolbar > Display Force-Vectors button.

Two equal and opposite Force-Vectors radiate from the Contact-Point between the Cam-Profile and the Follower-Roller. They are:

•the force vector that ACTS-ON the Follower-Profile and Follower-Part

•the force vector that ACTS-ON the Cam-Profile and Cam-Part

You must analyze if the force between the Cam-Profile and the Follower-Profile is active or not active (less than zero Newtons).

Method 2: Use: 2D-Cam dialog > Display tab > Cam Display Options > Contact-Force.

Plot with a Graph-FB:

Method 3: Add a Force-Data FB, select the 2D-Cam as the Force element, plot with a Graph FB.

Method 4: Use the Cam-Data FB to plot Contact Force from the top output-connector with a Graph FB.

Contact-Force is = 0 N if Contact-Force ≤ 0 N.

Note:

Method 4 is best if you need to know if the Contact-Force is less than or equal to zero