| 摘要 |
A fixing for a laminated material comprises an elongate shaft extending from a tip to a head, the shaft having an external screw thread comprising a first thread section proximate the tip and a second thread section proximate the head, the first thread section having a thread diameter or form that differs from a thread diameter or form of the second thread section thereby to adapt the first thread section to a different material. When used in a dry lined wall, this permits the first thread section to engage with the masonry in order to provide the necessary pull-out resistance. Meanwhile, the second thread section can engage with the plasterboard in order to hold the plasterboard in place (and therefore protect it) and also to use the resistance to shear forces that plasterboard is capable of providing. Thus, the first and second thread sections preferably have a combined length greater than about 20mm in length so that the first thread section can extend into the masonry. The first and second thread sections can have the same thread pitch so as to pass smoothly through the two layers without disturbing their relative position. Alternatively, such as for use in other laminate situations, the first thread section can have a thread pitch greater than that of the second thread section. This will tend to draw the outer layer more firmly toward the underlying layer. Such a fixing can be in the form of a screw or a plug. |
