Filament winding method and apparatus, and tank

A filament winding method for winding fibers around a tank composed of a trunk portion having a uniform radius in a tank axial direction and a pair of domed portions, wherein each of the domed portions communicates with a corresponding end portion of the trunk portion in the tank axial direction and is formed with a diameter that becomes smaller outward in the tank axial direction, comprising the steps of:

• a first step wherein while the tank, which is rotating, relatively reciprocates in the tank axial direction to a helical winding head, fibers are fed from each of a plurality of yarn-feeding sections to the tank, wherein the helical winding head includes the plurality of yarn-feeding sections arranged on a concentric circle around the tank;
• a second step wherein after the tank lastly turns back in the tank axial direction, a large number of fibers are wound around only one of the domed portions and the trunk portion of the tank at the outermost layer of the helical winding, trailing ends of the large number of fibers are located at one end portion of the trunk portion, and feeding of the large number of fibers from the helical winding head is stopped;
• and
• a third step wherein after the second step, a small number of fibers are fed from a rotating hoop winding head to the trunk portion, hoop winding is performed on the outermost helical winding layer formed around to the other end portion of the trunk portion, and feeding of the small number of fibers from the hoop winding head is stopped, and then at the one end portion of the trunk portion, the large number of fibers pulled from the yarn-feeding sections of the helical winding head are cut off.