Practice application and design of concave rollers
Abstract
A concave roller is an effective and inexpensive wrinkle-preventing roller design. By definition, a concave roller (a.k.a. a reverse-crowned roller) is a roller with a larger diameter at the edges than at its center. But a definition is not an engineering specification. What is the right amount of diameter variation? What is the best way to shift from large to small diameter? This paper will present a simple, logical approach to specifying a concave roller's profile tailored to roller and web properties. Beyond a concave roller's anti-wrinkle effects, they also have a lesser known web-to-roller traction benefit. Most air lubrication and traction models only consider cylindrical rollers. Concave rollers induce crossweb tension variations, creating crossweb differences in air lubrication and web-roller coefficient of traction. By combining concave roller tensioning with air lubrication and traction models, this paper will show how a concave roller will maintain good traction and better control under higher lubricating layers than a cylindrical roller of the same surface roughness or texture.
Citation
Walker, T. J. (2007, June). Practice application and design of concave rollers. Paper presented at the Ninth International Conference on Web Handling (IWEB), Stillwater, OK.