ENERGY-EFFICIENT AUTOMATED PROCESS FOR COMPOSITE TUBE MANUFACTURING VIA FRONTAL POLYMERIZATION

Conventional manufacturing of carbon fiber reinforced polymer (CFRP) tubes requires high energy consumption, long curing hours, large systems, and manual labor. In this study, we propose a design for an automated apparatus to continuously produce high performance CFRP composite tubes which leverage frontal polymerization chemistry, innovations in tooling, and oven design. Frontal polymerization of dicyclopentadiene (DCPD) uses the exothermic energy in the monomers to propagate a self-curing front and form a still poly-DCPD polymer. A long seamless sleeve of woven carbon fibers is pre-impregnated with uncured DCPD resin. The long sleeve is initially flattened and stowed upstream of the curing oven. The apparatus pulls the sleeve and opens it to form a hollow cylinder continuously by feeding it through in between an inner die (collet) and an outer die (hot ring). The apparatus has a novel design based on a kinematically constrained mandrel which fixes the inner die and other internal tooling. The kinematically constrained inner components include the axially-fixed expanding pressure collet which applies the pressure on the tube wall thickness during curing. This mechanical design enables continuous production of a hollow cylinder without restrictions on the tube length. The combination of fast curing resin, and mechanism design reduces energy consumption and cure times to produce composite tubes with good dimensional accuracy to those cured conventionally.