A novel method for spreading fiber rovings through forced conveying
Sprache des Vortragstitels:
Deutsch
Original Tagungtitel:
European Regional Meeting of the Polymer Processing Society, PPS-2024
Sprache des Tagungstitel:
Englisch
Englische Kurzfassung:
Unidirectional fiber-reinforced thermoplastic tapes (UD tapes) are increasingly used in lightweight construction for local reinforcement of components.
UD tapes are typically manufactured by a continuous extrusion process in which multiple fiber rovings are first unwound from a creel and then spread to form a homogeneous fiber carpet. This carpet is then pulled through an extrusion die, where it is impregnated with thermoplastic polymer melt. In the downstream steps, the tape is finally calibrated to the required thickness, cooled, and rewound.
A critical step in UD-tape manufacturing is spreading the fiber rovings into a homogeneous carpet by mechancial (through deflection or vibration), electrostatical, pneumatical, or acoustical means. The major goal of these techniques is to spread these fiber bundles homogeneously and uniformly, although each of consists of several thousands, partially twisted individual filaments. A consistently homogeneously-spread carpet is a prerequisite for a tape with consistent and homogeneous impregnation quality, which is a necessity for defect-free reinforced components.
A major challenge in fiber spreading is the inconsistent and scattering width of the fiber rovings within a bobbin or between different bobbins caused by the manufacturing process of the rovings. Especially for heavy tows ? carbonfiber rovings consisting of more than 24K filaments ? the variable input quality of the rovings hinders a constant final spreading width when employing existing spreading techniques.
A novel spreading technique based on the principle of forced conveying was developed aiming for constant spreading widths largely independent of the incoming roving quality. In a feasibility study, we investigated the forced-conveying-spreading behavior of two 24K, one 48K and one 60K carbon fiber rovings; our new spreading method provided constant spreading widths independent of the input width and cross-sectional shape.
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