17 April 2013:
Electromagnetic Press Rolls
As we have stated previously, we are going to be taking the ideas developed in this column over the last couple of years and developing them into design practices. This is how it works. We will provide the basic narrative here for one design practice each week. We will keep it open for comments for one month. After that, we will finish it in formal form and offer it for sale at a modest price. Here is where you come in. If you make a substantive contribution to a standard, the organization for which you work will be granted a pro bono license to use that standard with its current issue number for as long as you like. We have had good response so far! Contribute, please.
Electromagnetic Press Rolls (LGM 2013.015.01
Imagine very thin, very lightweight shelled press rolls. Inside an opposing pair of these press rolls are electromagnets which create the force, the pli, necessary for the press to function.
To use Electromagnetic Press Rolls on the paper machine.
The most important part of this concept is that the force necessary to make the press function is developed by the magnets, not by raw weight and air bags. This results in press frames having a singular function - necessary only to hold the light weight rolls in place in space. Weight is no longer a serious consideration.
Further to this concept, the magnets are not turned on until the rolls are up to speed. This reduces the starting torque, hence the size of all the components in the drive train.
As always, your comments will be appreciated.
Brian Brogdon, Ph.D.
(Regarding Cantilevered Dryers)
I work in narrow width machines and there is not much cantilevered beyond 20 inches in spite of its advantages for having an open-faced machine.
Certainly at that width the winder and rewind are much easier to do - they are the worst actors with cantilevering.
And it seems that the amount of iron on a cantilevered machine, is more than on the two side machine.
There is a strong interest in cantilevering the flexo press impression cylinder - we are moving to sleeves to reduce changeover times.
This might be a helpful place to learn some of the practical the engineering.
Send us your comments!