3D-Cam dialog-box

See also Add 3D Cam

Use the 3D-Cam dialog box to:

Set the number-of-points along the 3D-Cam, and across its flanks
Set the 'range' of the 3D-Cam (when it is an 'Indexing Cam')
Edit the display of the 3D-Cam in the graphic-area
Export the 3D-Cam to
oSolidWorks®
osave the data as number of text files

To Open the 3D-Cam dialog-box

1.Click the Mechanism name-tab in which you have added the 3D-Cam.
2.Click the 3D-Cam element in the Assembly-Tree or graphic-area
3.Right-click the 3D-CAD element
4.Click 'Edit element' in the contextual-menu

3D-Cam dialog-box

Dialog-13.2-3DCam

There are three tabs in the 3D-Cam dialog-box:

Cam
Display
Export

Buttons at top of the 3D-Cam dialog-box:

Rebuild button

Save Cam button

See below for more details.

Cam tab

tog_minus        Cam Surface Mesh Density 

Rims in 3D Cams

Rims along the Cam-Flanks (Purple), the Top and Bottom (Orange), and Points along each Rim.

Preamble:

We specify 3D-Cams with four(4) cam faces.
There are a number of lines, that we call Rims, along each cam face.
There are a number of points along each Rim.

The four (4) cam faces are the:

Two working faces.They are the Cam-Flanks.

The Cam Flanks are in continuous contact with the Cam-Follower Roller. There must be some clearance between the roller and the actual cam.

Two non-working faces. The Root-Face and the Top-Face.

The Root-Face is at the 'floor' of the cam. It should not contact the actual Cam-Follower Roller at any time.

The Top Face is 'outside' the cam diameter. It does not have a function in the actual cam. We use the Top-Face to close the 3D-Cam, when we export the data to SolidWorks, or save it as a STEP file.

Dialog-3DCam-Cam-CamMeshDensity

Parameters:

# Points along Rims:
Number-of-points along each Rim: '360' in dialog to left

# Rims along Flanks:
Number-of-rims across each flank (working faces) of the Cam: '6' in dialog to left

# Rims along Top & Bottom:
Number-of-Rims across the Root and Top (non working faces) of the Cam: '4' in dialog to left

# Hoops (data for CAD only)
Number-of-hoops that wrap around the 3D-Cam and connect the same Point along each Rim: '10' in dialog to left

The hoops help SolidWorks to keep the shape of the surfaces.

There is a minimum of 4 hoops if the Cam-Follower oscillates or reciprocates. That is, it is continuous.
If the Cam-Follower indexes, then Hoops are generated for you at the end-caps. There are 2.

tog_minus        Roller Parameters 

Taper-Roller VelocityDiagram-464

Preamble: Note: the equation: V = r ω [Linear Velocity = Radius × Angular Velocity]

The Roller-Parameter is the 'Taper-Angle' of the Cam-Follower Roller.

Why use a Taper-Roller with a Barrel and Globoidal Cam?

Different points on the cam-flank surface are at different radii from the cam's rotational axis. The tangential velocity of a points on the cam-flank at a large radius is greater than a point at a small radius.  The tangential velocities of all points on the surface of a rolling cylindrical roller are identical, because the radii of those points are identical.  Thus, the linear speeds of a cylindrical-roller and the cam-flank cannot be equal at all radii.

However, if you use a a tapered-roller, with an apex coincident with the rotational axis of the cam, then pure rolling can occur during the dwell periods, and nearly pure rolling during the motion periods.

Secondary-Contour-360-2

Nevertheless, cylindrical rollers are most often used as they are readily available, cheap, and can take high loads when they have needle-rollers.


What is the Roller Diameter of a Taper-Roller?

We cannot consider this until we understand the Extrusion-Offset and Extrusion-Depth parameters that define the Profile Extrusion of the Cam-Follower Roller.

In MechDesigner, to model a 3D-Cam, we sketch a circle to represent the diameter of the roller. We add a Profile to the circle to represent the cylindrical sides of the Cam-Follower. We use Extrusion dialog-box to make the Extrusion-Depth parameter equal to the 'Length/Width' of the Cam-Follower [usually given as the 'B' parameter in bearing catalogues].

Extrusion dialog-box:

Extrusion-Offset [mm]: Positive or Negative value

A dimension, that may be positive or negative.
Equals the position of the Primary-Contour [when the Part-Offset parameter is 0mm].

Extrusion-Depth [mm]:  ONLY a positive value.

Extrusion-Offset [mm] + Extrusion-Depth[mm]= the position of the Secondary-Contour.

Taper-Angle-360

Note: In image to the left, +Z-axis direction is downwards

Parameters

Dialog-R13-3DCam-RollerParameters

Taper-Angle [degrees] Inclines the Flanks of the 3D-Cam. The angle pivots about the Secondary-Contour.

With reference to the image to the left, we can see the

Positive Taper Angle increases the diameter in the +Z-axis direction.
Negative Taper Angle [shown in image] decreases the diameter in the +Z-axis direction.

Recommendation , if you are going to use the Taper-Roller parameter.

Below, we assume you have made sure the Mechanism Plane of the Cam-Follower is half way through the width of the Cam-Follower. It if is not, then change the dimension below to suit your model.

Taper-Angle-360-2

The Taper-Angle 'pivots' about the Secondary-Contour of the Extrusion Element that you use for the Cam-Follower:

1.Edit the Cam-Follower Extrusions with the Extrusion dialog-box

Enter these parameters:

Extrusion-Depth[mm] = 0.5 × Actual Roller Width[mm]
Extrusion-Offset [mm] = Extrusion-Depth[mm],

The Extrusion-Offset is the negative of the Extrusion-Depth. The Secondary Profile is on the Mechanism-Plane.

Then, the Taper-Angle parameter will rotate the cam flanks, pivoting on the Mechanism-Plane.

 

Taper-Roller Parameters-Settings-General-3

In the Clearances separator [in the 3D-CAM dialog, see below], enter:

1.Root-Clearance = minimum of 0.5 × Actual Roller Width[mm]
2.Add further Root-Clearance and Top-Clearance values to extend the flanks as required of the 3D-Cam, to suit your design.

tog_minus        Clearances 

Dialog-3DCam-Cam-RollerClearances

Preamble:

Clearances are practical considerations.

Clearance assumes the Cam is a Groove/Track Cam.

Positive Clearance values move the 3D-Cam faces away from the Cam-Follower Roller.


Parameters:

Radial-Clearance

A positive value 'pushes' the working cam-faces [flanks] outwards, to be outside of the cam-follower roller.
A negative value 'pulls' the working cam-faces [cam-flanks] inwards, to be inside the cam-follower roller.

Note: Total Clearance = 2 × Radial Clearance.

Clearance-TopRoot-360

Note: the Top-Clearance may be the Root-Clearance and Vice Versa.

Root-Clearance: This is intended to be the at the 'floor' of the cam-groove/track.

Use this parameter so that the Cam-Follower Roller does not touch the floor/root of the Cam Groove. A positive value extends the bottom, non-working face, nearer to the Centre of the Cam.

If the Extrusion Depth of the Cam-Follower Roller is the same as the width (B dimension) of the Cam-Follower Roller that you intend to use in your machine, then you should add Root-Clearance to give clearance between the bottom of the roller and the cam floor/root.

Top-Clearance: This is intended to be the an imaginary surface outside the working diameter of the Cam. We use it in SolidWorks to create a closed form.

A positive value moves the top, non-working face, further from the Centre of the Cam.

Make sure the top, non-working face is outside the maximum radius of the Cam-Blank.

 

Practically, the Radial Clearance is necessary to make sure that the Cam-Follower Roller does not jam as it slides along the Cam Groove in the Barrel or Globoidal Cam. My guide for Radial Clearance is approximately 1 ∕ 1000 of the Roller Diameter for accurately built machines.

As you increase the Radial Clearance there is more 'Play'. The motion of the machine will not be exactly the same as your motion design. Impacts and vibration occur each time the Cam-Follower Roller traverses the Radial Clearance. The greater the clearance, the longer the roller will skid before it reaches the rolling speed again.

To check the Cam-Follower-Roller does not show outside the four faces of the cam.

1.Increase the Number-of-Points to ~1 Point per 0.1º of cam rotation. Experiment for different size cams.
2.Rebuild the cam with the Rebuild button at the top of the dialog
3.Edit the Roller Extrusion. In the Edit Extrusion dialog-box, increase the Image Quality to High - the maximum Quality.
5.Step through the machine cycle with the F or B key. Or use the MMA spin box for smaller steps.
6.Inspect the Cam in the graphic-area to make sure the Cam-Follower does not break through the cam flanks and the Root of the Cam.

tog_minus        Flank Length 

Dialog-3DCam-Cam-RFlankLengths

Preamble:

Flank Length  parameters apply to Indexing Cams.

When you add a 3D-Cam, we calculate the coordinates for the cam over a complete machine cycle of the MMA, 0 – 360. However, cam-follower rollers of indexing cams do not stay in contact with the cam for a complete machine cycle 0 – 360. The cam-follower rollers progressively engage, then disengage with the cam, in a similar way to gear teeth.

We use the 'Flank-Length' separator to calculate the cam coordinates for the period only when one of the cam-followers is engaged with the cam. To do this we reduce the 'Flank Length' from a machine period of 0 and 360, to a period between two other machine angles.


Parameters:

You may need to edit the 'Flank Length' to calculate the cam for angles that are not  from 0 and 360.

To edit the Flank-Length:

1.Enter a 'Cam Start Angle' and a 'Cam End Angle'.

Start-Angle:

Edit the Start-Angle

End-Angle:

Edit the End-Angle

As you edit the Start and End Angle, you will notice the Cam becomes shorter in length.

The Number-of-Points that we calculate along each 'rim' in the cam does not change. Thus, the points along each rim become nearer to each other.

Display tab

tog_minus        Display in Graphic-Area 

Dialog-3DCam-Display-DisplayGraphicArea

Preamble:

The 'Display' edits how the 3D-Cam shows in the graphic-area.


Cam Display Options:

Solids* | Hoops | Rims check-boxes.

Solids*: show or hide, 3D-Cam as 'Solid' [with colour of the 'color' control, and with the Transparency %].
Hoops: show or hide a hoop at each Point along each of the Rims.
Rims: show or hide the Rims along the 3D-Cam

* You MUST select the Solids check-box to see the 3D-Cam in the Model-Editor other Mechanism-Editors.

Color

Use the Windows® colour-picker to select a colour of the 3D-Cam

Transparency

Use the slider to change the Transparency of the 3D-Cam.

Display Cam-Contour as...

Pressure-Angle
Cam-Profile

When you show the 3D-Cam as Pressure Angle, the faces have a colour-code.

Red identifies a high Pressure-Angle
Blue identifies a low Pressure-Angle

Minimum / Maximum

By default, the colour-code scales to the maximum and minimum values of the Pressure-Angle

If you want to change the scale, use the Maximum Value and Minimum Value boxes.

Auto-scale button

Click the auto-scale button to reset to the maximum and minimum values again.

Export tab

tog_minus        SOLIDWORKS Paths 

Dialog-3DCam-Export-SWPaths

Preamble:

After you have sent the 3D-Cam to SolidWorks, it is often useful to link the file-name in SolidWorks with the 3D-Cam in MechDesigner.

At a later date, when you open this 3D-Cam dialog again, you can use these buttons to open the part in SolidWorks.


Controls:

Get Cad Part Path button

Click this button to link the CAD file-name in SolidWorks with the 3D-Cam.

The file-name is put into the Cam Part Path box

Open Cam Part button

The Open Cam Part button open the CAD file that is in the o open the file in the box

tog_minus        SOLIDWORKS Data Transfer 

Dialog-3DCam-Export-DataTransfer

Preamble:

When you have set the correct parameters: Flank Lengths, Clearances, Mesh Density, Range, then you can export the cam to SolidWorks.

1.Open SolidWorks
2.Add a new Part and make sure the new Part is 'active'
3.Press the three buttons in the SolidWorks Data Transfer separator

Buttons:

Send Cam Blank button

MechDesigner exports the sketch of the 'Cam-Blank' and its 'Axis-of-Rotation'.
MechDesigner instructs SolidWorks to add a revolved feature with the Cam-Blank and 'Axis-of-Rotation'.

Note: Typically, the sketch of the Cam-Blank is symmetrical about the middle of the sketch. If the sketch is not symmetrical (top to bottom), then it is possible that SolidWorks will put the sketch 'up-side-down' with respect to the 3D-Cam. To flip the Cam-Blank, mirror [ in SolidWorks] the sketch about the Y–axis and then the X–axis.

Send Cam Surfaces button [Note you can also save the Cam as a STEP file, to import directly into your CAD.

MechDesigner exports each Rim and Hoop
MechDesigner instructs SolidWorks to:
oCreate a surface from the Rims for each face and flank of the Cam
oAdd end-caps to the surfaces, if it is an Indexing-Cam
oKnit the surfaces together

Remove Surfaces from Blank button

MechDesigner instructs SolidWorks to:
oCut the knitted surfaces into the Cam Blank
oHide the knitted surfaces

Note: You may need to edit the Surface Cut feature to reverse the direction of the cut.

tog_minus        Rebuild and Save Cam buttons

Dialog-3DCam-RebuildSaveButtons

Rims in 3D Cams

Rims along the Cam-Flanks (Purple), the Top and Bottom (Orange), and Points along each Rim.

Rebuild button

Click the 'Rebuild' button:

to recalculate the 3D-Cam with updated parameters
before you transfer the 3D-Cam to SolidWorks
before you save the 3D-Cam to text files

Save Cam button

Click the Rebuild button before you save the model

Click the Save button.

The Windows Save as dialog opens.

File type: ASC and SLDCRV

The data in each file is the XYZ coordinates of the Points on a Rim. Each Rim is saved to a different file.

In the image to the left, there will be 20 separate files - one file for each Rim.

File type: STEP [recommended]

The STEP file is very efficient. You can open the STEP file in most other 3D CAD.

Note:

From the STEP file, I do these steps:

In SolidWorks:

1.Open the STEP file of the Cam, and immediately save the model as a SolidWorks STLPRT file.
2.Open or make a solid model of a Cam-Blank
3.Use Insert menu > Part... and select the file of the SolidWorks Step file [see 1]

You may need to Move the Cam with Insert > Feature > Move/Copy

4.Use Insert > Feature > Combine : Subtract to cut the STEP file from the Cam-Blank.

 

 

tog_minus        Example Steps to Transfer a 3D-Cam to SOLIDWORKS

SolidWorksPArt

Make sure the active document is a Part document.

STEP 1: Open SolidWorks®
STEP 2: Add a new Part
STEP 3: Save the new Part

3D-CadDatTransfers-1

See Download SW Type Libraries

3D-SolidWorks-BarrelBlank

STEP 4: Click the 'Send Cam Blank' button

Step 4 is Complete

MechDesigner controls SolidWorks to:

1.Use the Sketch and Rotation Axis in the Cam-Blank Mechanism to make the Cam-Blank.

See Getting Started Tutorials 6C for more information.

You can see 'Sketch1' and 'Revolve1' in the SolidWorks Feature Manager.

MD-3DBarrel-CadSurfaces

STEP 5: Click the 'Send Cam Surfaces' button

To make the transfer quicker: Show a drop-down menu in SolidWorks® for example the 'help' menu'! [we do not know why this is makes the transfer faster].

MechDesigner controls SolidWorks to:

1.Make the Rims as 'Curve' entities
2.Make four Surfaces features (or six if the Flank-Lengths are not from 0 – 360)
a.two Cam Flanks, a Cam Floor and Cam Top
b.plus two 'End-Caps' if the Flank-Lengths are not from 0 – 360.
3.Knit the Surfaces

MD-3DBarrel-SolidWorksCutCam

STEP 6: Click the 'Remove Surfaces from Cam' button

The 3D-Cam Surfaces are 'Cut' into the Cam Blank.

Wait!

STEP 7: Save the Part In SolidWorks®

3D-BarrelCam-Negative-Space

If You can edit the 'SurfaceCut1' features in SolidWorks to and reverse the direction of the cut. If STEP 5 does not work, then 'manually' in SolidWorks® , use:

1.Insert > Cut > With Surface
2.Select the Knitted 3D-Cam Surface - the last feature in the Feature Manager.

Frequently, you will get the 'negative-space' of the cam. See image.

3.Edit the 'SurfaceCut' feature in SolidWorks® and click the 'Change Direction' button.
4.'Hide' the Knitted 3D-Cams Surface.

Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd