| 摘要 |
<p>A hybrid screw (S, S'') comprises a flared head (10, 10''), a cylindrical stem (12, 12'') and a distal pointed section (14, 14'') with the flared head (10, 10'') defining a cruciform opening (16, 16''). The cylindrical stem (12) defines a longitudinal inner bore (18) which communicates with the cruciform opening (16) of the head (10) and which defines longitudinal splines (19) adapted to be tapped by a further fastener. A side opening (20) is defined in the cylindrical stem (12) to allow for material cut by the hybrid screw (S) to evacuate through the inner bore (18). First (24, 24'') and second (26, 26'') thread sections of a common thread (22, 22'') extend helically around the cylindrical stem and the distal pointed sectin respectively. The first thread section (24, 24'') is large to firmly engage a friable material such as gypsum, whereas the second thread section (26, 26'') is adapted to cut through gypsum but also to engage a wooden component, such as two by four studs typically found behind gypsum sheets in walls. The hybrid screw (S, S'') which is longer than the thickness of the gypsum sheet can be used at a location in the wall opposite a structural stud thereof, the second thread section (26, 26'') then engaging the wooden member without reducing the axial advancement per rotation of the screw (S, S'') and thus of the first thread section (24, 24'') into the gypsum wall. As both the first and second thread sections have a substantially same pitch, both the cylindrical stem and the distal pointed section will be firmly secured in the gypsum and in the wooden member, respectively.</p> |
