| 摘要 |
PROBLEM TO BE SOLVED: To render a hollow extruded shape lightweight wherein members each having two surface plates and a rib for connecting the plates are connected together by frictional agitation jointing. SOLUTION: The surface plates 21 and 22 of the hollow shape 20 are connected in end-to-end relation by the rib 24 and are connected to the ends of the surface plates 11 and 12 of another hollow shape 10 by frictional agitation jointing. The outer line of the connection between the end of the surface plate 21 (22) and the rib 24 comprises arcs 31 (33) and 32 (34) which dent toward the hollow shape 20. The diameter of the arc 31 (33) is smaller than that of the arc 32 (34). Thus, the hollow extruded shapes can be rendered lightweight. |
