| 摘要 |
<p>A fire-resistant door is assembled from a panel of sheet metal enclosed between two layers of plywood and supported on a hardwood frame and an ancillary hardwood frame covered on the opposite face with plywood and carrying fittings such as hinges, handles etc. The hardwood frames are linked by slots engaged by loose keys. Pref. bonds between the hardwood frames and the plywood covers are made using rigid adhesive, e.g. urea formaldehyde based. The interfaces between the sheet metal layer and its plywood covers are bonded by a relatively flexible adhesive. Pref. silicone mastic based, to accommodate differential thermal expansion. Easier to transport and install, as two or more separate panels, assembled in situ, than fire break doors involving one or more full-size metal panels and prefabricated as complete doors.</p> |
