Method for spreading fiber bundles, spread fiber sheet, and method for manufacturing a fiber-reinforced sheet

Abstract

The present invention has an object to provide a fiber-spreading method which can form a thin spread fiber sheet having a large and uniform spread width by uniformly distributing fibers of a fiber bundle having an increased number of fibers. Since a set of regions Seach including a pair of a fiber-spreading region Aand an expansion region Bare arranged in a movable region M set so that the fibers of the fiber bundle can move in the width direction, the fiber-spreading region Amoving the fibers in the width direction while bending the fibers by letting a fluid pass through the fiber bundle, thereby spreading the fiber bundle to a spread width W(i=1, . . . , n), and the expansion region Bwhich is set on the upstream side in the feeding direction corresponding to the fiber-spreading region Aand in which the width of the fiber bundle expands toward the end with movement of the fibers in the width direction in the fiber-spreading region A, by performing pre-spreading in which a movement phenomenon in the width direction caused by distribution of the fibers of the fiber bundle occurring in the fiber-spreading region Ais made to act on the expansion region Bon the upstream side, the fibers can be uniformly distributed in the fiber-spreading region Aand the spread width can be expanded to a predetermined width so as to make the thickness uniform.