Rolling of recycled plastic fibers

A model was developed for the processing of recycled plastic flakes into fi bers to study the effect of the various processing parameters. Verification of the fiber rolling model was done by comparing it with the standard flat rolling model, i.e., rolling into flat sheets, by looking at the sample ro ll-face pressure distributions for the two processes. The roll-face pressur e distribution for fiber rolling and flat rolling showed the same basic cur ve profile, but the fiber rolling had a higher magnitude for the pressure. It seemed reasonable that the rolling and cutting of the plastic into fiber s would require a higher roll pressure than the rolling flat sheets. Rollin g operations have a neutral point on the rolls, which is the point of maxim um or peak pressure. The neutral point for fiber rolling is slightly nearer to the entry compared with hat rolling for the same percentage reduction i n cross-sectional area. After verifying the fiber rolling model with the flat rolling model, a para metric study was performed on the fiber rolling model, which showed how the processing parameters affected the roll-face pressure distribution and the torque required to turn the rolls: the coefficient of friction between the rolls and the plastic flakes, the size and shape of the fibers created, th e initial thickness of the plastic flakes, and the roll radius. The model w as useful in understanding the basic science of the fiber rolling process, and would be useful in optimizing the design of a rolling mill if this is d eveloped into a commercial process. (C) 2000 Elsevier Science S.A. All righ ts reserved.