| 摘要 |
<p>1465896 Nail STEEL CO OF CANADA Ltd 16 May 1974 [29 March 1973] 15199/73 Heading F2H The invention comprises a combination of a metal joist layer 24, a panel layer 22, and a nail 10 having a threaded portion 14, cylindrical portion 16, and conical portion 18, the threads 19 having an outer diameter greater than the maximum diameter of the conical portion and a thread angleαbetween 35 and 55 degrees, the length between the apex of the conical portion to the start of the threads being not less than the thickness of panel layer, and the length of threaded portion being at least as great as the combined thickness of the metal joist layer and panel layer, the nail securing the layers together with its head against the panel layer and with the threaded portion extending through both layers. The head may be flat as shown, or of rounded or countersunk form (Figs. 2, 2A, not shown).</p> |
