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A wall plug (UK English)〔In US English, a wall plug would likely be understood as an electric socket on a wall.〕 or screw anchor (US English), commonly called a "rawl plug" or dowel in British or US English respectively, is a fiber or plastic (originally wood) dowel used to enable the attachment of a screw in material that is porous or brittle or that would otherwise not support the weight of the object attached with the screw.〔(Oxford Dictionaries )〕〔(American Heritage Dictionary )〕 It is a type of fastener that for example allows screws to be fitted into masonry walls. There are many forms of wall plug, but the most common principle is to use a tapered tube of soft material, such as plastic. This is inserted loosely into a drilled hole, then a screw is tightened into the centre. The screwing action wedges the plug firmly in place, the soft material conforming tightly to the masonry. Such fasteners can attach one object to another in situations where screws, nails, adhesives, or other simple fasteners are either impractical or ineffective. Different types have different levels of strength and can be used on different types of surfaces. == History == Before commercial wall plugs, fixings were made to brick or masonry walls by chiselling a groove into a soft mortar joint, hammering in a crude wooden plug and then attaching to the wooden plug. This was time consuming and required a large hole, thus more patching of the wall afterwards. It also limited the holes' location to the mortar joints. The original wall plug was invented by John Joseph Rawlings in 1911, and marketed under the name ''Rawlplug''. These plugs became popular after the First World War, when a demand for retro-fitting existing buildings with new electric lighting coincided with a shortage of labour, encouraging many new labour-saving innovations in the building trade. Rawlplug gained their prominence from their adoption in the British Museum.〔(【引用サイトリンク】url=http://www.rawlplug.se )〕 Early wall plugs were thick-walled fibre tubes, made of parallel strings bonded with glue. Most current brands are plastic, first designed in 1958 by Artur Fischer, known as the Fischer Wall Plug. Some early plugs, including Rawlings', were also made of soft metal strips, punched with raised perforations for grip. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Wall plug」の詳細全文を読む スポンサード リンク
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