Question Regarding Crowned Roller Geometry in a Driven Nip
I have a crowned roller in the nip on a laminating machine. The nip is driven and the nip rollers are chain driven together with identical gearing. We have a crowned bottom nip roller to help even our nip pressure. We are still having uneven nipping at the edges, which is causing me to reevaluate our roller design. According to our testing, the lamination is even across the width, but in certain products it is pretty clear that the edges are getting pulled harder and causing a longer edge that will curl and stipple.
My question is, with a crowned roller pair with a non crowned roller, should the edge diameter of the crowned roll (so the area with no appreciable crown) match the diameter of the uncrowned roller? Or should the max diameter of the crowned roller (center) match the diameter of the uncrowned roller?
Looking at our rollers, the max diameter matches the top roller, and the edges are undersized. Could this cause a speed variance at the edge of the web? Or does the deflection of the roller take that up?
I'll pose this question to the roller manufacturer as well, but thought I would throw it out here. Thanks!
Submitted July 26, 2017 at 11:17AM by aboyd656
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