Patent ID: 7056594

Claim:
A friction stir welding method, comprising the steps of: abutting a first panel and a second panel, each of said first and second panels comprising a first plate, a second plate which is substantially in parallel to said first plate, and a third plate connecting a midway of one end side of said first plate and said second plate; positioning outer faces of said first plates of the first and second panels at substantially a same plane; abutting said first plates of the first and second panels together, the third plates of the first and second panels being spaced from each other when the first plates are abutted; providing an additional plate member extending between the third plates of the first and second panels, such that an abutted portion is formed between said additional plate member and said second plates of the first and second panels, overlying said third plates; and under a condition where said first plates are mounted on a bed and under a condition where a rotary tool is inserted to said abutted portion from an upper location, carrying out a friction stir welding of said abutted portion.