Webex’s rugged bowed rolls provide effective web handling for the most demanding web converters — available in both permanent bow and adjustable bow models. Proven mounting solutions ensure ease of installation as well as extended versatility in web control. These precision bowed rolls are ideal for separation of slit webs, or the elimination of web wrinkles, slack edges and soft spots. Exceptional performance is evidenced in the even distribution of lateral web tension and vibration-free operation at all specified speeds.
Also referred to as a concave roll, reverse crown or bow tie roll, the reverse taper roll has a larger diameter at the outer edges and a smaller diameter at the roll centerline. The roll, as a result of its profile, creates a surface speed differential at each different roll diameter. The resulting tension differential, or higher edge stress, ultimately results in the material climbing outward toward the larger diameter edges of the roll.
To be effective the web and the roll must be in a state of traction and therefore, web tension and wrap angle are very important components to the effectiveness of reverse taper rolls. The amount of taper or crown depends on the application but generally is .0005" to .001" per inch, diametrical taper from the roll centerline to the edge. Reverse taper rolls are definitely the most cost effective web spreading devices. They have an advantage in that, even if they do not achieve the desired action, they can still be effectively applied anywhere in the line as general idler rollers.
These anti-wrinkle rolls can influence your web in various ways, including stretching it, spreading it or allowing the web to lay flat and simply not induce wrinkles in the first place.
These idlers are covered with a rubber elastomer and are precision machined with angled, outward spiraling grooves across the roll surface. There are different elastomers available for use, each with different physical properties such as solvent resistance, heat resistance and hardness. In addition, various groove patterns are available to meet your specific application needs. Our Customer Support Specialists can help you determine which elastomer and groove pattern is best for your specific application.
Grooved metal rolls are also often applied as wrinkle removal devices. Because there is no scientific reason that these should be effective, Webex engineers do not actively recommend the use of grooved metal rollers. However, we have many users in real-world applications that swear by the effectiveness of grooved metal rolls as wrinkle removal devices.