To reduce the weight of a hollow shape material that is joined by friction stirring welding.
The end of the face plates 111, 112 of a shape material 110 is connected by a rib 116. The projecting pieces 117, 117 of the rib are superposed on the end of the face plates 101, 102 of the other shape material 100. The joining line between the rib 116 and the rear face of the face plates 111, 112 is joined by a circular-arc 131 projecting to the hollow side 119 of the shape material 110. Both ends of the circular-arc 131 are connected to the rib 116 and the face plates 111, 112 in the form of a smooth recessed circular-arc 132, 133. As a result, there is no flow-out of metal from the relative part, so that the cross-section can be made smaller and lighter.
SATO AKIHIRO
FUKUYORI KAZUNARI
KAWASAKI TAKESHI
KASADO KIKAI KOGYO KK