Thread: electronic gearing question

JUKI AMS Texprocess Movie. - YouTube

Take a look at the machine shown at 4:33. They have taken a standard sewing machine that has a top shaft and bottom shaft that is usually linked via timing belt. If the rotation of the bottom shaft is just slightly off, it won't sew right. I am amazed at the speed obtained and accuracy that has to be there.

Is this pretty standard for electronic gearing or is there something special going on? I have several applications a machine separated from top and bottom shafts would be an easy solution.

Thanks

Jason

This can be done a number of different ways using a variety of different controllers.

This is not unlike rigid tapping on a milling machine where the Z-Axis move is slaved to the spindle rotation - We have done rigid tapping on some machines that use a registered tap so that the threads are the same every time and you can even start the program over and run the tap down the same hole multiple times without damaging the tapped hole in any way.

If this application was done with gearing - you would additionally need a "registration" correction that would get the two axes into alignment with one another. I doubt this is the way it was done.

More likely - they have a virtual master and two slave axes that are "geared" to the master. This allows more control of accelerations / velocity so that tighter servo loop gains can be achieved.

Thank you as always for the direction. I am assuming this is something I can do with the unidrives? I have got a project brewing for something similar.

Regards,

Jason

Yes, you would need an aux encoder module plus a motion made ez module on the slave drive, we have done this many times with the unidrive

Something to be aware of in a follower or electronic gearing application is the motors will have a bit of "give" to them.

For example, if one motor is following another and the follower is subjected to a sudden load, it may briefly lag the master if the motors are not sufficiently sized and the drives are not tuned to respond very quickly.

The control will sense the encoders are not in sync and correct, but the motors need to be sufficiently oversized if there is any danger of mechanical clash in this type of application.

Chris