| 摘要 |
PROBLEM TO BE SOLVED: To improve the rigidity of support legs 11 made of a metal and to easily form the support legs 11 made of the metal. SOLUTION: A pair of C-shaped metal members 1 includes: side plate portions 2 provided with a plurality of parallel support holes 5 for inserting a plurality of raising or lowering arms side by side; upper plate portions 3 bent from the corresponding side plate portions 2; and lower plate portions 4 bent from the corresponding side plate portions 2 and opposed to the upper plate portions 3. Each metal support leg 11 of an annular cross-section, which is formed by butting and welding the upper plate portions 3 of both the C-shaped metal members 1 and also butting and welding the lower plate portions 4 thereof, includes: a top plate portion 12 formed from the upper plate portions 3 welded together; a bottom plate portion 13 formed from the bottom plate portions 4 welded together; both opposite side plate portions 2; and an empty space 14 extending by its being surrounded by the top plate portion 12, the bottom plate portion 13, and both the side plate portions 2. Placing bases made of the metal are interspatially welded on and across on the top plate portion 12 of the support legs 11 made of the metal such that the placing bases interspatially extend between the support legs 11. COPYRIGHT: (C)2010,JPO&INPIT
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