WEBANCOR BOWED ROLL PRIMER
What is the purpose of a Bowed Roll?
How does it work?
The Bowed roll is similar to an idler roll except that it has a rubber type covering and the face length is in the configuration of a bow, instead of being straight. The inside of the roll is full of bearings to support the rubber convering, and allow the roll to be bent and still rotate. When the web passes over a straight idler roll the web direction changes vertically because of the amount of "wrap". When the web passes over an offset idler roll, the web direction will change vertically because of the "wrap" and also horizontally because of the roll being offset. The bowed roll can be considered a double offset roll, and the web will try to follow the offset of the roll, since the offset esentially goes both horizontal directions at the same time the web follows both ways, with the result that the web tries to stretch in width removing wrinkles, or spreads slits in a slitter application. The amount of spread or stretch depends on the amount of wrap and the amount of bow. There are many calculations available in the design of the Bowed Roll, however these should be used only as a guide and a starting point, since such variables as web material, tension, web width etc can cause changes to the result. When the product varies on a "daily" basic it might be wise to consider a Adjustable Bowed Roll. A fixed bow can be used successfully when the same product is used continuously, and rarely needs to be changed.
What is the difference between a Fixed and an Adjustable Bowed Roll?
What type of rubber covering should be used?
What diameter of roll should I use?