To obtain the outer surface without projecting and recessing parts by providing a projecting part protruded on the surface at the one side part in the thickness direction of the plate in the end part of the first plate, inserting a rotary tool into the butted portion from only the projecting part side under condition of abutting a backing on the surface at the other side part, executing a friction-joining and also positioning the surface at the other side part to the outer surface.
The end part of the first plate and the end part of the second plate are butted. The end part of the first plate is provided with the projecting part protruded on the surface at the one side part in the thickness direction of the plate in the first plate, and the rotary tool is inserted into the butted portion from only the projecting side part under condition of abutting the backing on the surface at the other side part in the butted portion, and the butted portion is friction-joined and also, the surface at the other side part in the butted portion is friction-joined as substantially flat state. The friction-joining is executed by laying the surface at the other side part in the butted portion and substantially on the flat bed. The surface at the other side part of a structure obtd. with the friction-joining is positioned to the outer surface of the structure to manufacture the structure.
ISHIMARU YASUO
TAKENAKA TAKESHI
