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Preventing negative issues at nip roller

Bass, Tom
Nagahori, Atsushi
Dealing with film scratches, wrinkles, and air entrapment is a problem that many converters are faced with on a regular, if not daily basis. Part of the problem is the rollers they have to work with at the nip point. Granted, rubber covered rollers at the nip point is a proven technology that has been utilized for many years. However, with the technological advancements in designing and manufacturing Carbon Fiber Reinforced Plastic (CFRP) rollers there are benefits to consider in utilizing this technology at the nip roll.
Carbon fiber rollers can be designed and manufactured as single-pipe or double-pipe depending upon the performance requirements of the roller. At the nip roller is where the majority of the benefits can be realized with the double-pipe design. While this double-pipe roller design is not new and is known as Airy or Bessel Point support, the historic design included a steel or an aluminum double-pipe roller with bearings attaching the inside to the outside pipe to reduce deflection of the nip roll.
The double-pipe carbon fiber roller utilizes a lightweight carbon fiber inner and outer roll as well as carbon fiber attachments from the inner to the outer roller. This design allows for 1/3 - 1/10 the deflection of a single-pipe carbon fiber roller design. The lower roller deflection causes a reduction in cross web pressure variation at the nip roller.