| 摘要 |
<p>A fire-protective door panel comprises a shallow box 3 formed by two metal sheets 1, 2 of which lower horizontal edge strips 4, 5 are angled in U-shaped manner in cross-section and are connected to one another by a weld seam 8 whilst edge strips 4', 5' are folded to form a rabbet. Arranged inside the box 3 is a stiffening frame 9 made of gypsum which encloses an insert or core 16 of insulating material. Intumescent strips 17 may be provided. <IMAGE></p> |
