Add the Stationary Cam

tog_minusPreparation 2C: Add the Rocker

6D2-1-015

We will not design the tool. We will only add the Rocker to the sliding-part.

STEP 1: Edit the sliding-part
STEP 2: Add a vertical Line

See the image to the left.

 

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STEP 3: Add a Part
STEP 4: Add a Pin-Joint

See the image to the left

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STEP 5: Add a Motion-Dimension FB so that the Part is now a Rocker
STEP 6: The angle of the Rocker relative to the vertical Line is 135º.
STEP 7: Rename this Part to Follower.

We now want to synchronize the Motion of the Follower with the Motion of the sliding-Part.

6D2-1-018

We want a Slot Cam to rotate the Cam-Follower.

We must add a  sketch and Profile to represent the Cam-Roller Follower

STEP 8: Edit the Rocker, renamed as Follower.
STEP 9: Add a Line and Circle, as indicate to the left.
STEP 10: Close the Part-Editor
STEP 11: Add a Profile. Use the Circle.

We can rename the Circle Profile to Cam-Roller Follower.

Plan the motion for the Slot Cam

First: What do we want the Stationary Cam to look like?

6D2-1-019

The image to the left shows the design we want. It has a Slot CamRed-14-1b. To remind us, ....

... the Angle of the Rocker is a function of the motion of the Sliding-Part, NOT the MMA.

What is the difference between Design 1, 6D1, and this Design 2, 6D2?

Design 1: We can get the motion of the Sliding-Part directly. Its motion is the output from the Motion-Dimension FB.

Design 2: We do not know the motion of the Sliding-Part directly. The Sliding-Part is one Part in an R-R-P Dyad.


Note: the Motion of a Part includes its Position, Velocity, and Acceleration motion-values.

6D2-1-020This is the Motion for the Rocker that we have prepared.

Q: How can we get the motion of the sliding-part?

A1: METHOD 1

Use a Measurement FB to measure the position (and motion) of the sliding-part

A2: METHOD 2

Use a Point-Data FB to give the position (and motion) of the sliding-part relative to the origin of the Base-Part.

tog_minusMethod 1: Add a Measurement FB

A Measurement FB measures the distance between sketch-elements

In this case, we will measure the distance from a stationary sketch-element in the Base-Part to a moving sketch-element in the sliding-part.

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STEP 1: Add a sketch-element to the Base-Part
1.Edit the Base-Part
2.Part-Editor: Add a vertical LineRed-14-1b
3.Exit the Part-Editor

 

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STEP 2: Add a Line to the sliding-partRed-14-2:
1.Edit the sliding-part
2.Part-Editor: Add a vertical Line

The Line is vertical, from the start-Point of the sliding-part.

3.Close the Part-Editor

 

6D2-1-023

STEP 3: Add a Measurement FB to measure the perpendicular distance between the two LinesRed-14-3Red-14-4
1.Click Kinematic FB toolbar > Add Measurement FB
2.Mechanism-Editor: Click the PointRed-14-3 at the top of the Line in the Sliding-Part.
3.Mechanism-Editor: Click the LineRed-14-4 in the Base-Part
4.Mechanism-Editor: Click the graphic-area
5.Run toolbar > Cycle (or ALT+C)

The two Lines should not move past each other as you cycle the model. If they do, move the Line in the Base-Part more to the left.

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STEP 4: Add a Graph FB to find the range of the motion.
1.Click Kinematic FB toolbar > Add Graph FB  | then click the Graphic-Area.
2.Mechanism-Editor: Connect a wire from the Measurement FB to a Y-input of the Graph FB

The Measurement range in my model is: Minimum = 20.000mm; Maximum = 221.44mm

You can see the Maximum and Minimum values if you open the Graph Settings from the Graph FB.

Graph Settings dialogs > Y-axis | Minimum and Maximum values.

6D2-1-020A

STEP 5: Add a Motion FB
1.Click Kinematic FB toolbar > Add Motion FB | then click the graphic-area.
2.Edit the Motion FB to open the Motion FB dialog-box
3.Click the Select-Motion drop-down arrow and select the Rocker motion in MotionDesigner
4.Close the Motion FB dialog-box
5.Connect a wire from the output-connector of the Measurement FB to the Motion FB.

In the image, the Red lines/arrows indicate the range of output from the Measurement FB (20 up to 220 down to 20). This is also the input, or X-axis, to the Motion FB. Thus, the output from the Motion FB is limited to those values in Blue on the Y-axis.

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STEP 6: Connect the Function-Blocks
1.Connect a wire from the output-connector of the Motion FB to the input-connector of the Motion-Dimension FB (Rocker).

Note: The motion-units from the Measurement FB are NOT important. It is the number value provided to the Motion FB that are important.


STEP 7: Add the 2D-Cam
1.Click Machine elements toolbar > Add 2D-Cam
2.Click the Base-Part
3.Click the Follower Roller

MechDesigner adds the 2D-Cam to the Base-Part / Machine Frame.

Notes:

If the X-axis motion of the Slot Cam has a range greater than 360 units, then edit the motion in MotionDesigner to increase the X-axis to be greater than 360. Remember, the units of the Motion FB X-axis are dimensionless.
It is best to make sure the Measurement FB does not output a negative value.
You can use a Gearing FB to 'scale' or 'shift' the output of the Measurement FB to suit the motion and the requirements of the Stationary Cam.

Tutorials and Reference Help Files for MechDesigner and MotionDesigner 14.2 + © Machine, Cam, Mechanism, and Motion Design Software by PSMotion Ltd