6C3: Examine 3D-Cams for Cam-Follower Clearance

3D-Cams have complex surface geometry. If you want to manufacture a Globoidal Cam, we recommend that you make sure the MechDesigner model and the 3D-Cam in SOLIDWORKS® agree. In other words, if you give a 'Flank Clearance' of 0.005mm (see 3D-Cam dialog-box) in MechDesigner, the SOLIDWORKS® model should agree with this clearance throughout the indexing and dwell motion.

This tutorial uses the CAD-Control FB to move an assembly model in SolidWorks (you must prepare this), to the same as position as the MechDesigner model. Then you can use the Clearance Detection tool in SolidWorks to see whether the Flank-Clearance' Parameter, as set in the MechDesigner model, agrees with the clearance as found in the SolidWorks model.

If the communications with the CAD-Control FB fails, enter the two 'angle mates' (see below) manually in SOLIDWORKS.

Add the CAD Control FB to the graphic-area:

The CAD Control FB is now in the graphic-area.

Use the CAD Control Function-Block to synchronize the positions of Parts in a SOLIDWORKS® Assembly model with the Parts in a MechDesigner model.

Q: Why do this when MechDesigner is perfect to model motions?

A: Because SOLIDWORKS® has useful tools that include:

The Clearance Detection Tool in SOLIDWORKS shows the exact gap between Parts.

We connect motion-values from Function-Blocks that move the indexer to the CAD Control FB.

When you configure the CAD Control dialog-box, motion-values from the indexer model in MechDesigner are 'piped' into 'Distance' or 'Angle' Mates of an equivalent assembly in SOLIDWORKS®.

The motion of the SOLIDWORKS® model is the same as the MechDesigner model. It is much slower than MechDesigner - do not use Cycle in MechDesigner.

This example is the CamCo® Part Number M601RDM4H24-330 in CamCo Catalogue, Page B-4.

There are two motions:

In SOLIDWORKS®, we have:

Clearly, the Cam-Box and Cam-Follower Turret/Wheel are very simplified. However, they are configured in the same way as the Cam-Box in the catalogue.

The 'Front' Plane of the 3D-Cam should be the 'Front' Plane in SolidWorks®.

Here, we add mates(SolidWorks® terminology) – that we want to control, with motion-values, from the MechDesigner model. The mates are:

The image to the left shows the 'mates' added to configure the three Solid Parts.

The two (highlighted) Mates – 'Angle 2' and 'Angle1' – are the Mates 'driven' by the Cad Control Function-Blocks.

(You can rename these Mates. I renamed them to 'Output Cam-Follower' and 'Output cam-shaft').

Notes on 'Angle' Mates in SOLIDWORKS:

Angle mates in SOLIDWORKS® cannot be 'negative'. They can only have a range from 0º to 360º'.

The output from an Angle Motion-Dimension in MechDesigner has a possible range of -180º to 180º. Much larger if we select the 'Accrue Index Motion' check-box in the Motion FB dialog-box.

The 'Relative' Positive and Negative sense of the Mate should be the same in SOLIDWORKS® and MechDesigner. That is, if you increase the Angle in SOLIDWORKS® by 10º and MechDesigner, the Part in the two models should move in the same direction. You should test which is positive in the Angle Mate Control in SOLIDWORKS.

The motion of the 3D-Cam (Input Shaft) and the motion of the Cam-Follower (Output Shaft) are in different Mechanism-Editors. We must make them available in one Mechanism-Editor.

We must add an indexing Cam-Follower Part in the Cam-Shaft Editor

In the image to the left ('Show Model in Mechanism' is Toggled IN'), the Part and the Function-Blocks in the 'Red Rectangle' have been added.

Note: Even though the Motion-Dimension value is 225º, the output value from the Angle Motion-Dimension FB itself is -135º!

As we cycle the Model in MechDesigner, the -135º value increases in the Positive sense to 0º and up to 225º.

The Angle Mate in SOLIDWORKS® is '+225º'.

Note: It is not possible to make angle negative in SOLIDWORKS®, thus we add 360 to –135º' to give 225º

We have configured the angle mate to increase in the same positive sense.

To do this we:

MechDesigner checks that you have the correct Type Libraries installed.

This may take 20 seconds.

With the SOLIDWORKS model open:

The dialog-box, 'finds' the correct mates in SOLIDWORKS.

Note: I renamed the mates in SOLIDWORKS from Angle2 and Angle1 to 'Output CamFollower' and 'Input CamShaft'.

Now, the positions of the Parts in SOLIDWORKS move when you move the Parts in MechDesigner.

The connection is slow – say a step per second.

Use the 'Step Forward', 'Step Backwards' or the 'Home' buttons – DO NOT USE THE CYCLE buttons.

It is possible to use the 'Interference Detection' and 'Clearance Verification' tools in SOLIDWORKS®.

The Cam-Follower moves to the angular position given by the Modified-Sine Motion-Law, with Constant-Velocity of 33%, in the MechDesigner and SOLIDWORKS models.

(If this does not happen the communication between MechDesigner and SOLIDWORKS has not worked.

Do not worry. Manually enter the angles in SOLIDWORKS.

you must read the two angles in MechDesigner and manually set the angles in SOLIDWORKS

The SOLIDWORKS 'Clearance Validation' Tool shows the clearance as 0.00389mm.

(I typically put 5μm (0.005mm) clearance between the Cam-Follower and the 3D-Cam in the 3D-Cam dialog-box – dependent on the 3D-Cam or Cam-Follower Size)

This means the data sent to SOLIDWORKS:

and / or