Step 16.2: Motion-Path FB, Ram-R

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Step 16.2: Motion-Path FB, Ram-R

Motion-Path: Ram-R and Ram-P

We can use the Motion-Path FB to build two new pseudo-dyads:

•Ram-R

•Ram-P

An application of the Ram-R dyad is to model an engine valve and cam where we want to control the distance between the center of the cam-shaft and the center of the roller on the rocker.

Another application is to control the motion of a linear actuator that drives a scissor lift.

Kinematics of a Ram-R

GST-16-2-MD-RamR-F

Ram-R

The Ram-R is a similar to an R-R-R dyad. In the Ram-R dyad, one of the Parts extends.

The Ram-R uses the Motion-Path FB to add a Motion-Point to a sketch-element ( in the image, the CAD-Line) in one Part.

We join the other Part to the Motion-Point with a Pin-Joint.

We add a motion to the input of the Motion-Path FB to control the motion of the Motion-Point.

The Red Arrow is the path of the Motion-Point along the CAD-Line of one of the Parts.

tog_minus        How to add a Ram-R

GST-16-2-MD-RamR-A

STEP 1: Add two Parts and join with Pin-Joints to a Line in the Base-Part.

1.Edit the Base-Part | Add Line, Add Dimension 100mm, Add Horizontal Constraint

2.Close the Part-Editor

3.Add two Parts

4.Edit the length of the Parts =100mm

5.Add Pin-Joints between the start-Points of each Part and the end-Points of Line
Motion-Path FB

Motion-Path FB

STEP 2: Add a Motion-Path FB

1.Click Kinematics-FB Toolbar > Add Motion-Path FB

Add the Motion-Path FB to a CAD-Line (a sketch-path)

2.Click the CAD-LineRed-14-1 along the center of the Part

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

The default position of the Motion-PointRed-14-2 is at the start-Point of the sketch-element you select (in this case the CAD-Line), and coincident with the Pin-Joint on the left.
Motion-Path dialog-box

Motion-Path dialog-box

STEP 3: Edit the start Position of the Motion-Point.

There are two Parts that you have joined to the Base-Part with Pin-Joints. You will add one more Pin-Joint (See STEP 4) to give three(3) points of a triangular shape. Motion values at the input to a Motion-Path FB will control the length of one of the sides of the triangle before we add the final Pin-Joint.

1.Edit the Motion-Path FB

In the Point Parameters separator

2.Edit Linear OffsetRed-14-5 = 40mm

3.Close the dialog

The Motion-PointRed-14-3 is now 40mm from the start-Point of the CAD-Line.
GST-16-2-MD-RamR-D
GST-16-2-MD-RamR-E

STEP 4: Add Pin-Joint

1.Click Kinematic-elements toolbar > Add Pin-Joint

2.Click the end-PointRed-14-4 of the Cad-Line and then the Motion-PointRed-14-3 that is at 30mm along the CAD-Line

The Pin-JointRed-14-5 joins the two Parts. The Ram-R dyad is now defined.

The Parts are kinematically-defined, with Green Part-Outlines.

You may need to change the closure of the Ram-R dyad.

STEP 5: Change Dyad Closure

1.Kinematics toolbar > Change-Dyad-Closure

2.Click one of the two Parts.

3.Click OK-tiny-13-17 in the Command-Manager to complete the command.

STEP 6: Add a Linear Motion FB and a Motion FB

STEP 7: Edit the Data Type at the output from the Motion FB

When you connect a Motion FB to a Motion-Path FB, you MUST edit the Output Data-Type to Linear or Rotary (the Data-Type should NOT be Motion).

1.Edit the Motion FB to open the Motion FB dialog

In the Motion FB dialog:

2.Enable LinearRed-14-4 as the Output Data-Type

Close the dialog.

STEP 8: Edit the Motion in MotionDesigner

The maximum displacement is 50mm.

STEP 9: Connect the Linear-Motion FB to the Motion-FB to the Motion-Path FB

GST-16-2-GA-CamMotion

Add a 2D-Cam

GST-16-2-GA-CamProfile

Note: The motion of the Follower will not useful for an engine.

STEP 1: Add the Follower-Roller

1.Edit PartRed-14-9 Add Circle, Add Dimension, Add Coincident Constraint  

Constrain the circle to the end-Point of the CAD-Line

2.Do Solid menu > Add Profile

3.Click the circleRed-14-11
GST-16-2-GA-RamR-09

 

STEP 2: Add the Cam-Part

1.Add a PartRed-14-12 and join it with a Pin-Joint at the left of the Line in the Base-Part*.

2.Add Motion-Dimension FB - so that PartRed-14-12 is a Motion-Part (Rocker).

3.Connect a Linear-Motion FB to the input of the Motion-Dimension FB.

4.Edit the Motion-Dimension FB > Base-value = 0.

PartRed-14-12 is the horizontal Cam-Part.

* The Select-Elements dialog opens. CTRL + CLICK the start-Point of the PartRed-14-12 and the start-Point of the Line in the Base-Part.
GST-16-2-GA-RamR-11

STEP 3: Add the 2D-Cam

1.Do Machine elements > Add 2D-Cam

2.Click the new PartRed-14-12 as the Cam-Part.

3.Click the ProfileRed-14-11 as the Follower-Profile

The 2D-Cam is now in the graphics-area.

 
GST-16-2-GA-RamR-12

Kinematics-Tree

We call this kinematic-chain the Ram-R dyad

Kinematic-Chain #1 : The R-R-R is the Ram-R dyad - normally, this would be a structure. But a motion controls the length of one of the Parts in the dyad.

Kinematic-Chain #2 :The Rocker represents the Cam-Shaft.