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17-Peridot

## Flywheel analysis with Creo Mechanism

Hi all,

I wonder if it is possible to study the relevance of the insertion of a flywheel in the motion chain.

I expect to see something by looking the Net Load at the servo motor.

My mechanism is a group of an automatic machine: a brushless motor moves a shaft whith two cams that let shift up/down some shafts.

Ideally tha angular velocity of the motor (+ reducer) is constant at 840 deg/sec.

The equation of the motion is:

Mm= motor moment

Mr= resistant moment

Jr= inertia momentum reduced to the camshaft

If I add a flywheel on the camshaft I can't see any variation of the Mm.

I suppose the reason is that by imposing a constant velocity, the contribute of the Jr (not its derivative) is always zero.

For now I don't want to take the resistant moment Mr due to the external forces.

Since that I imposed the velocity as a constant, the angular accelration, theta double points, is always zero.

If I add a flywheel on the cam-shaft I don't see any variation on the net load (Mm) respect when the flywheel there wasen't because I add to Jr a constant (constant because the flywheel is added on the camshaft that is the axis where I have reduced all the inertias) component so dJ/dtheta don't vary.

To see any variation I would need to resolve the 2° equation, but I don't think that it is possible inside Mechanism. Or yes?

I am able to extrapolate the function (by points) of Jr and its derivate, that are linked to the system and not to the velocity by two analysis:

1) velocity = constant; I can extract the dJ/dtheta by measuring the net load at the motor (Mm) and by having the velocity imposed.

2) by imposing a force motor, not servo motor, at the cam-shaft; I used the curve of the net load measured previusly, but it was not important the profile of the Mm, it is important that the profile of Mm is imposed (known) so by measuring the angular volecity and the accelartion in mechanism, I can obtain the function of J.

So I think that is possible to resolve the motion equation numerically (Mathcad or excel?) but how?

My goal is to observe how vary the Mm (and the velocity of the camshaft) during the cycle by varying the inertia on the camshaft by manteining a velocity of 840 deg/s as constant velocity, like a feedback loop that always try to reach and keeping the full speed of 840 deg/s.

Thanks

Bye

Thread modified by Giulio Fraulini. I've changed the section from "creo - Analysis and Simulation" to "Mathcad".

5 REPLIES 5
23-Emerald I
(To:gfraulini)

I spent a little time working on this.

I think where the problem lies is that you need a derivative of inertia (J) with respect to angular position; that's not something you can solve for.

23-Emerald I
(To:Fred_Kohlhepp)

You can develop inertia versus speed--a centrifugal governor:

23-Emerald I
(To:gfraulini)

Attached is a Mathcad (Prime 3.0) file that can take a defined function for J(theta) and M(theta) and solve for the angular position and speed.

17-Peridot
(To:gfraulini)

Hi

I'm sorry for the delay of the answer.

Is what I've done correct?

How can I do?

The program is made with MC15.

17-Peridot
(To:gfraulini)

Maybe I have to specify the characteristic of the motor?

I have a brushless Yaskawa, model SGMGV-20D.

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