Originally posted by Fred Floggle:
You'll have to have a diameter from the winder so that torque compensation and speed compensation can be carried out?
This is a surface winder so the winding drum speed isn't influenced by diameter, as is the case with a center winder. So speed compensation based on diameter isn't an issue. A case could be made that you want to modify the drive velocity loop gains as the diameter builds. However, I wouldn't get into that unless it's absolutely necessary. it's not that it's particularly difficult. It's just that it often isn't necessary.
Originally posted by Combo:
but, when u wind a carpet, when of the 2 blocks, the torque shoot decrease; can I do that wit current limitation ?
What's the formula of Torque (with the use of current in it)
You really want to modify the torque limit in the second drive, not the actual current limit. If the MM440 is operating in closed loop vector mode this should be possible. Using current limit in an AC drive to control torque with any accuracy can be a little tough.
However, I still think you want to go with a full velocity system. If you go with a torque based system you need to know how much torque is being used just to overcome friction and inertia losses in order to figure out how much torque you need to tensioning. The only way this will work with any accuracy is if you are sure the 'system' losses (friction) are
MUCH less than the required tension torque.
If it is a typical two-drum winder, the first roll the material contacts sets the base winder speed and may be tweaked based on tension feedback from upstream. The second, farther downstream, roll runs at some ratio (or percent draw) to the first. This draw sets the amount of web stretch as the roll is wound, which is what determines the inwound tension and, ultimately, roll hardness.
If you really want to go the torque route you will need to look up how to map a torque limnit value from your plc into the approporiate torque limit of your second roll drive. You probably also want to read back both the roll drives actual torque values.
Hope this helps.
Keith