| 摘要 |
<p>The sheet metal panel door is constructed of two identical flanged sheets which fit together via tongues and grooves provided on the vertical door edges. A cross section through each sheet presents a long base assymetric 'U', with an inward square return provided on the shorter leg end, and a similar return on the other leg end which then bend through 180 deg. and continuous to terminate in a further external square return. These returns form tongues and grooves respectively and the panel is assembled by a vertical sliding together of inversely related sheets. The terminal leg on the groove formation, aligns parallel to the panel edge, is set back from the panel edge by a distance equal to the sheet gauge, and serves as a guide for the tongue.</p> |
