need help determing which direction to go in

[douggroh]

We have an assemly line that pushes material out at 4 meters per minute. We cut the material into blanks. Our guillotine chops the material to length, but it also stops it. If we could have the pull rolls sensing what tension is on the rolls, we could speed up the motor to make up the difference in speed the materail is running at.

https://files.engineering.com/getfi...a-81f9-a04c375d99e7&file=torque_converter.jpg

 

[LittleInch]

Can you edit your post so that it makes sense. I think I got it eventually, but it's not clear.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[douggroh]

Thank you, Littleinch.

 

[MintJulep]

The typical way to do this is move the cutter at the same speed as the material.

This is rather low-tech, but illustrates the fundamental concept nicely. Moving Head Cutter

 

[Compositepro]

Since the cutter is not moving with the web, it must stop when being cut. Nothing you do with the pull rolls will change that. You can either stop the rollers during the cut, or let the material buckle between the rollers and the cutter. If you allow buckling, then the measured length between cuts may change.

Many thin webs do not have enough stiffness to be pushed between the rollers and the cutter, particularly if the web has already buckled. That is why multiple drive belts are often used above and below the web to carry it to the cutter. They cause the web to be wavy (corrugated) in the cross plane, which makes the web stiff in the machine direction so that the web can be pushed into the cutter. The cutter will flatten the web as it cuts it.

There is only light friction between the drive belts and the web (no pinch) so the material can stop during the cut, without stopping the belts.

 

[douggroh]

Our materials are thicker and higher in the GSM than many nonwovens.

 

[jlnsol]

Hi Douggroh,

In dough sheeting lines it is common practice to add a horizontal movement to the guillotine knife in sheet running direction. This happens at sheet speeds from 1 m/min up to 15 m/min so 4 m/min should be no problem at all. The only difference between these guillotines and yours is that yours has a counter bar at the bottom which need to be moveable as well then, where dough machines cut directly onto the conveyor belts. Is it possible to add a pivot point above the guillotine where the whole unit rotates around? Cutting synchronized with the web speed will can increase your production a lot.

 

[berkshire]

In the sheet metal industry The shear/guillotine that cuts continuous sheets to length is called a flying cut off. Because during the shearing operation it travels with the sheet at the same speed, for the time of the cut, then returns to the start position for the next cut.
B.E.

You are judged not by what you know, but by what you can do.

 

[Ron]

Put the cutter or cutters on a rolling wheel as well. Circumferential distance between multiple cutters on wheel could dictate length of cut as well if you wanted. Nothing stops....continuous operation.

 

[douggroh]

Thank you all for your contributions. I will make my report accoringly.