| 摘要 |
Disclosed is a first type of dowel which is composed of at least two longitudinal braces and transversal braces. Such a dowel is compact such that a drilled hole can have the same diameter as or only a slightly larger diameter than a screw. A second type of dowel comprises a band-shaped base, at least one surface of which is provided with spaced-apart projections that extend at an angle to the longitudinal direction of the base. Such a dowel is easy to produce, has great retention force, and can be used for various screw types and sizes. A third type of dowel is composed of an elongate element in the form of a cylinder segment, the cross-section of which has the shape of a segment of a circle. The drilled hole can have a small diameter because the dowel is located only on one side of the screw. The non-symmetrical design prevents the dowel from rotating along with the screw when the latter is screwed in. Since the dowel is open on one side, thread grooves can be molded thereinto and/or a lubricant can be applied to the internal surface of the dowel. The screw thread digs in a claw-like manner into resilient material, while the dowel is retained on the other side by compression. A fourth type of dowel comprises a threaded bar encompassing an externally threaded section as well as a first and a second internally threaded element which are screwed onto the externally threaded section of the threaded bar. A locking element is placed on the threaded bar, between the internally threaded elements, by means of a continuous bore, is provided with at least one locking area, and is semi-rigid at least in the region of the continuous bore. Said dowel can be used for a range of drilled holes and requires only a small depth of the hollow space. Drilled holes require only a comparatively small diameter for mounting the dowel. |
