| 摘要 |
The metallic top plate comprises: a rectangular plate; a first, a second, a third, and a fourth side plate bent downwards in a vertical direction from each of sides of the rectangular plate; a first, a second, a third and a fourth bottom plate bent inwards in a horizontal direction from each of lower ends of the first to fourth side plates; corner forming pieces bent toward the third and the fourth side plate to be in parallel with the third and the fourth side plate while being formed to be extended to both ends of the first and the second side plate facing each other among the first to the fourth side plate such that corners are formed; fifth bottom plates bent inwards in a horizontal direction from lower ends of the corner forming pieces; and welded pieces welded while being formed on side ends of the first and the second bottom plate and being overlapped on boundaries between the third bottom plate and the fifth bottom plate and on boundaries between the fourth bottom plate and the fifth bottom plate. The present invention performs an overlapped welding operation on the bottom without avoiding a welding operation at corners, thereby making a grinding operation unnecessary. |
