| 摘要 |
<p>The crossbeam for metal shelving, with longitudinal axis horizontally disposed, comprises a sheet of steel bent cylindrically in which the upper wall and the lower wall each comprise a series of layers of the steel, united one to another along bend lines parallel to the longituidinal axis of the crossbeam. A first layer (11, 21) occupies about a first half breadthwise of the wall. A second layer (12, 22) is externally superposed on the first layer. An external third layer (13, 23) occupies the whole wall breadthwise. A fourth layer (13, 24) is internally superposed on the third layer and is coplanar to the second layer. A fifth layer (15, 25) is coplanar to the first layer. The crossbeam can be manufactured simply and rapidly and can be used for making considerably strong metal shelving. <IMAGE></p> |
