To provide a sheet back frame which can control the deformation of a side frame to a backward load by sharing a cantilever reclining and a inboard reclining by the same frame.
This sheet back frame 1 consists of right and left symmetric side frames 2a and 2b, and upper pipe 3 bonded by welding to both upper tip parts on the side frames 2a and 2b, a lower pipe 4 bonded by welding to the lower part of the side frames 2a and 2b. The side frames 2a and 2b are in a front opening shape widening a front side 12a than a rear side 12b. the faces of the side frames 2a and 2b are provided with triangle planes by adjusting the side frames 2a and 2b in a vertical direction to fold and bend the common edge of the adjacent triangles (shown by dotted lines in the Figure).
MIZOO AKIHIKO
MIZUNO RYOZO
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