Step 11.2: Add DYADS to the Piggyback Sliders

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Step 11.2: Add DYADS to the Piggyback Sliders

Add 3× R-R-R dyads

Add two dyads between the Piggyback Sliders and the machine frame (Base-Part).

It is then possible to drive one of the Parts in each dyad from the frame, and thus drive the Piggyback Sliders, with cams or servomotors. The cams and servomotors are fixed to the machine frame.

Dyads that we can use.

We can use any of the five dyads. To keep the principle simple, we will add in this tutorial two R-R-R dyads.

1.First R-R-R dyad: Connect to Slider-X and the Base-Part

2.Second R-R-R dyad: Connect to Slider-Y and the Base-Part

3 × R-R-R dyads

btn_delkeywordR-R-R dyad #1: between Slider-X and the Base-Part

GST-11-2-B-001

STEP 1: Prepare the Parts to locate the R-x-R (Pin-Joints)

1.Edit the Base-Part: Add Horizontal LineRed-14-1 to locate the R-x-x (Pin-Joint) in the Base-Part. Close the Part-Editor

2.Edit Slider-X*, Add a LineRed-14-2 to locate the x-x-R (Pin-Joint) in Slider-X. Close the Part-Editor.

* Optionally, edit Slider-Y

STEP 2: We can now add the Parts and the Joints for the R-R-R dyad #1

3.Add two Parts. Add a Pin-JointRed-14-3 two join the two Parts

4.Add Pin-JointRed-14-4 to join a Part to Slider-X (* or to Slider-Y)

5.Add Pin-JointRed-14-5 to join a Part to the Base-Part

btn_delkeywordR-R-R dyad #2: between Slider-Y and the BasePart

GST-11-2-B-002

STEP 1: Prepare the Parts to locate R-x-R (Pin-Joints)

1.Edit the Base-Part - Add Horizontal LineRed-14-1 to locate the R-x-x (Pin-Joint) in the Base-Part. Close the Part-Editor

2.Edit Slider-Y - Add a LineRed-14-2 to locate the x-x-R (Pin-Joint) in Slider-Y. Close the Part-Editor

STEP 2: Add the Parts and the  3x Joint the R-R-R dyad #2

3.Add two Parts.

4.Add a Pin-JointRed-14-3 two join the two Parts together

5.Add Pin-JointRed-14-4 to join a Part to Slider-Y

6.Add Pin-JointRed-14-5 to join a Part to the Base-Part

btn_delkeywordOPTIONAL: R-R-R dyad #3, with a Bell-Crank

Question: Why a  R-R-R dyad #3?

Answer: To drive the Piggyback Sliders from a position that is nearer to the drive of the 1st dyad. See the Bell CrankRed-14-2.

GST-11-2-B-003

STEP 1: Prepare the Parts to locate the R-x-R (Pin-Joints)

1.Edit the Base-Part - Add Horizontal LineRed-14-1 to locate where we join the R-x-x Pin-Joint in the Base-Part.

2.Edit a Part in dyad #2,  Add a LineRed-14-2 as a Bell-CrankRed-14-2 at 90º to the CAD-Line to locate where we add the x-x-R Pin-Joint .

3.Edit Slider-Y, Add a LineRed-14-2 to locate where we join the R-R-R dyad to Slider-Y. Close the Part-Editor

We can now add the R-R-R dyad #3

4.Add two Parts.

5.Add a Pin-JointRed-14-3 two join the two Parts

6.Add Pin-JointRed-14-4 to join one Part to the Bell-CrankRed-14-2

7.Add Pin-JointRed-14-5 to join a Part to the Base-Part

Now, the two Parts that drive the mechanism are near to each other.

This is more convenient place in the machine to add cams and servomotors.

Please watch the Video.
btn_delkeywordCalculate the Degrees-of-Freedom and Mobility

GST-11-2-B-004

DEGREES-OF-FREEDOM

The design has 9 Parts

•1 × Base-Part

•2  × Slider

•3 × dyads = 6 Parts

The design has 11 Joint

•3 × dyads = 9 Joints

•2 × Sliders

Gruebler EQUATION:

F = 3(P–1) – 2J  : (P = Parts ; J = Joints)

F = 3 × (9–1) – 2 × 11

F = 24 – 22 = 2

Degrees-of-Freedom = 2

MOBILITY

Mobility = Degrees-of-Freedom – Number of Motion-Dimensions.

Mobility = 2 – 2 = 0

How do we Drive the design so that we follow the XY Path?

We can use:

•Servomotors : We would need to save the motions of the Parts that you want to drive to a text file, and format it for the servo controller.

•Cams and Followers : Add the Follower-Rollers and Cam-Shafts. See Tutorial 6.

btn_delkeywordAdd 2D Cams to Drive the Parts

 

 

The video clip is of Piggyback Sliders, driven by two 2D-Cams
btn_delkeywordAlternative Configuration of the 2D Cams

 

 

This is a more convenient configuration. Now two cams are on one cam-shaft.