| 摘要 |
PURPOSE:To realize horizontal frames with no thermal deformation by a structure wherein lugs at both ends of each of some horizontal frames, which may be easily deformed thermally and consist of a part of a group of horizontal frames, are shiftably fixed by means of stepped screws. CONSTITUTION:The length (a) of the second horizontal frame 4b from the top out of six horizontal frames 4a-4f, for example, is made a little shorter than the distance (b) between a pair of vertical frames 5 so as to form clearances (c) on both sides of the frame 4b. The horizontal frame 4b has lugs 7 with respective elongated holes 8 at its both ends so as to be shiftably fixed to the vertical frames 5 by stepped screws 9. The horizontal frames 4a, 4c, 4d, 4e and 4f excluding 4b are fixed to the vertical frames 5 by claws 6, which are provided at both ends of each of the frames excluding 4b. Because a part of the horizontal frames, which are easily deformable by hot air, are shiftably mounted to the vertical frames by stepped screws, the expansion and contraction of the horizontal frames are absorbed by the shifting of the frames, resulting in preventing the horizontal frame 4b from deforming thermally. |
