6A2.2: Swinging-Offset Flat-Faced Follower

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6A2.2: Swinging-Offset Flat-Faced Follower

Summary

This tutorial is Add Cam with an Oscillating Flat-faced Follower

It is very similar to Add Cam with Translating Flat-faced Follower - see Tutorial 6A2.1

Add Parts: Cam-Shaft and Follower

In MechDesigner, the Parts for a Cam and a Follower can be in complex Kinematic-Chain.

However, in this tutorial, we keep it simple. The cam rotates as a Cam-Shaft and Swinging Flat-Faced Follower is a Rocker. The two Parts are joined to the Base-Part.

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STEP 1: Add a Mechanism-Editor

STEP 2: Edit the Base-Part

1.Part-Editor: Add a Line - its start-Point will be the center of the Cam-Shaft

2.Part-Editor: Add a Line - its start-Point will be the center of the Swinging-Follower

3.Part-Editor: Add dimensions and constraints to the sketches

4.Exit the Part-Editor

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STEP 3: Add a Crank and the Swinging-Follower

We add two Parts - the start-Point of each Part is joined to the start-Point of each Line in the Base-Part.

1.Mechanism-Editor: Cam-Shaft : Add Part, Add Pin-Joint, Add Motion-Dimension FB

2.Mechanism-Editor: Swinging-Follower : Add Part, Add Pin-Joint, Add Motion-Dimension FB

3.Mechanism-Editor: Add Linear-Motion FB : Connect a wire from the Linear-Motion FB to the Motion-Dimension FB for the Cam-Shaft.

4.Mechanism-Editor: Add Motion FB : Connect a wire from the Linear-Motion FB to the Motion FB, and then a wire to the Motion-Dimension FB for the Swinging-Follower.

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STEP 4: Edit a Motion for the Swinging-Arm Follower - about 25 degrees.

Add the Flat-faced Follower

The Flat-Faced Follower must be a sketch-loop. One of the sketch-elements must be a Line.

The best shape for a Flat-Faced Follower is a long, narrow rectangle. The long side of the rectangle becomes the contact face.

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STEP 1: Edit the Swinging-Follower Part to add a sketch-loop

1.Double-click the Part-Outline of the Swinging-Follower

2.Part-Editor: Add LineRed-14-1b that will be in contact with the cam

3.Part-Editor: Add Lines to give a rectangle : LineRed-14-2 that is very short in comparison to LineRed-14-1b . LineRed-14-1b  and LineRed-14-2 are perpendicular (⊥).

4.Part-Editor: Complete the sketch with dimensions and constraints.

5.Exit the Part-Editor (e.g. Double-click a sketch-element)

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STEP 2: Add a Profile/Extrusion to the sketch-loop

1.Mechanism-Editor: Click Solids toolbar > Add Profile

2.Mechanism-Editor: Click the sketch-loopRed-14-1b

3.Mechanism-Editor: Click OK-tiny-11-15 in the Command-Manager

In this case the flat-face follower is offset to the Pin-Joint.

 

Add the 2D-Cam

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STEP 1: Add a 2D-Cam

1.Click Machine elements  toolbar > Add 2D-Cam

The Command-Manager has two selection boxes for two elements:

1.Mechanism-Editor: Click a Part - click Part-Outline of the Cam-Shaft Part Red-14-1b

2.Mechanism-Editor: Click a Profile - click the Flat-Faced Follower Profile Red-14-2

3.Click OK-tiny-11-15 in the Command-Manager.

You can see in the image that the cam does not seem to be correct Red-14-3

The problem, in this case, is classic under-cutting.

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STEP 2: Edit the Motion

1.Edit the motion so that the Rise or Return segments are longer.

Use the Blend-Point Editor > X-Axis value.- see MotionDesigner Help.

Dialog-R13.2-CamDisplay-CamVisibilities

Lastly we need to hide the 'external' Cam with the 2D-Cam dialog-box.

The external cam is either Cam 1, or Cam 2.

STEP 2: Edit the 2D-Cam

1.Mechanism-Editor: Click the 2D-Cam in the graphic-area.

2.Selection-Window: Right-click the 2D-Cam element

3.Selection-Window: Click Edit element in the contextual menu

The 2D-Cam dialog-box opens.

5.2D-Cam dialog-box: Cam Display tab > Cam Visibilities > de-select Cam 1 (or Cam 2)

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Note:

In the 2D-Cam dialog-box it is also possible to show the 'Pitch-Curve', which is nonsense with a Flat-faced Cam Follower.