Step 6D1.3: Add the Stationary 2D-Cam

<<<This is the motion we prepared for the Rocker in Step 6D1.2

The motion has 2 × Ramps

IMPORTANT NOTE:

Imagine the X-axis Units are mm and NOT degrees.

Then it is easy to imagine that the X-axis is equal to the motion of the Slider.

Let's look ahead:

This 2D-Cam will looks like the Rocker motion.

We will look at four methods to add the 2D-Cam. We will explain the problems and advantages of each.

A Cam-Roller is a Profile element.

STEP 2:

Click the Circle in the Rocker Part | Click in the Command-Manager.

There are two terms that we use.

We must click two elements:

Click in the Command-Manager to add the 2D-Cam.

The Cam does not have 2 × Ramps!

We can view the Pitch-Circle-Path:

The Function-Blocks have been connected as:

MMA(0-360) > Motion-FB(0-90) > Slider

MMA(0-360) > Motion-FB(2 × Ramps) > Rocker

Hence, the input to Motion FB (2 × Ramps) is 0 to 360 and thus its output is identical to the Motion Design in MotionDesigner.

IMPORTANT CONCEPT

If we delete the wire from the input to the Motion-Dimension FB for the Slider, the Slider will not move - obviously.

However, the Rocker continues to do its motion. This is because the input to the Motion-Dimension FB for the Rocker has an input from the Linear-Motion FB (MMA) and the Motion FB (2 × Ramps).

However, the Rocker should not move if the Slider does not move.

This method will move the Slider at Constant-Velocity. Thus, the input to the Slider is equal to the input of the Rocker Motion FB.

The output from the Linear-Motion FB is constant-velocity. The output from the Rocker Motion FB is now 2 x Ramps, while the Slider moves steadily,

As the input to the Slider is now 0 -360, the Slider will move 30mm (Base-Value) to 390mm (Base-Value + Motion-Value) with Constant-Velocity.

It then instantly moves to 30mm after each 0-360 cycle of the MMA.

However, the motion-design of the Slider has a motion-range (as intended) of 90mm to move the Slider from 30mm to 120mm.

To reduce the output from the Linear-Motion FB from 360 to 100mm, we can use a Gearing FB

STEP 5:

Connect a wire from the Linear-Motion FB to the Gearing FB and then a wire to the Slider Motion-Dimension FB.

When look at Cam 1 and Cam 2 - and not only the Pitch-Circle, there is serious undercutting of the Cam.

Now the stationary cam has 2 × Ramps is as we intend it to be.

Excellent. ... However, ...

Question 2: Why is it not an excellent result?

Answer 2: The Slider Cam looks like a 'Snail'!

The Slider moves at constant-velocity in one direction, and then jumps back to zero. It does not have the motion-design Slider that is in MotionDesigner.

We want the 2D-Cam for the Slider AND the Stationary 2D-Cams.

<<< Click the image to expand and collapse.

As stated above. We want a Cam to rotate the Rocker and also a Cam to move the Slider.

We will add all of the wires again.

Its output is, of course, the Slider motion that we have designed in MotionDesigner ( a Range of 0-100)

Its output controls the Slider Part - which will move by the BASE-Value(30) + Motion Values . ( a Range of 30-130)

This is the normal way to connect a Motion-Part.

This is the IMPORTANT STEP!

The input to the Rocker Motion FB now has a motion-range from 30 -100.

This is equal to the X-axis of the motion in the Rocker name-tab in MotionDesigner.

The image to the left indicates the input range, or the X-axis motion-values, on the Motion graph, which is at the input to the Rocker Motion FB

The motion-values (30 to 130) increase from 30 to 130 and then decrease again from 130 to 30 - exactly as does the Slider motion.

The output motion-values from the Motion FB have a range of 0 to 10 - the Y-AXIS of the motion in the Rocker motion name-tab.

The input to the Rocker Motion-Dimension FB is 0 to 10(Y-axis of Rocker motion). To find the angle of the Cam-Roller relative to the X-axis, we simply need to add up these values.

The Motion-Dimension is relative to the vertical line in the Slider Part =+90°, the Motion-Dimension FB > Base-Value = +230°, the Line for the Cam-Roller in the Rocker Part is at +30° .Thus +90+230+30 =350° or -10°

Thus, the Motion-Range, relative to the X-axis, rotates the Cam-Roller from -10 to 0.

Note: You will get a message in the Feedback area: '1 Mechanism dependencies detected'. It is advisable to rebuild the model when the number of dependencies becomes more than 1.

The Slot-Cam looks near to complete. However: it is not complete?

The motion-values at the input (the X-axis) to the Rocker Motion FB have a motion-range = 30 - 130.

We want the motion-range at the input (X-axis) of the Rocker Motion FB to be 0 to 360.

Thus, we need to move the starting point of the input(X-axis) from 30 to 0, and the maximum value to 360, but still be a function of the output from the Slider Motion-Dimension FB

We can use a Gearing FB.

STEP 2:

Connect a wire from the Slider Motion-Dimension FB to the Gearing FB.

STEP 3:

Connect a wire from the Gearing FB to the 2 × Ramps Motion FB.

The range of values at the output-connector of the Gearing FB is now 360

However, ...

To correct this offset we can use one of two possible other parameters in the Gearing FB.

Add After Gearing Ratio

This parameter is added after the input is multiplied by the Gearing-Ratio

Thus if we enter the -108

Add Before Gearing Ratio

This parameter is added before the input is multiplied by the Gearing-Ratio

Thus if we enter the -30

Thus, we get the same result in the two cases.

<<< The Gearing FB parameters.

We can see that the Slot-Cam now has the correct-profile.

We do NOT need to design the motion for the Rocker with an X-axis motion-range of 360.

We can design the Rocker motion with an X-axis motion-range of 100.

Also, we can start the Motion at 30 and not 0.

The new Motion Table is as follows. The Y-axis is the same.

The Slider-Cam and the Slot-Cam will now be the same as Method 3.