| 摘要 |
<p>The upper and lower board sheet plates (3, 4) have a flap (16) provided with a U shaped recess including arms with top connected to two pavements (20). Each pavement is connected to lateral side walls (5, 6) and to a lateral face wall (7) through folding lines. Self-centering units e.g. inverse V-shaped recesses (32) and wedges (33), assure self-centering of the upper board sheet plate on the lower board sheet plate through fitting of a reinforcement i.e. rectangular movable plate (31), of a base between external edges of the pavements.</p> |
