DOWEL FASTENERS

Abstract

A fixing is described with a head portion (2), preferably formed as a headed stud (8, 9), and a dowel portion (1). The dowel portion (1) has a generally polygonal, preferably square, cross-section, and on each face is formed a series of barbs (4). The fixing is designed to be hammered into a hole of internal diameter corresponding to the external size of the shaft. Once inserted, the barbs (4) prevent easy extraction, e.g. from a chipboard or mdf-based furniture component. The fixing may have an axial hole (12) through which a secondary fixing, such as a headed screw, may pass, in order to render the force needed to pull the fixing out even greater.

Claims

1. A fixing for insertion into a cylindrical cavity, the fixing being formed of a slightly resilient plastics material having a head portion and a shaft extending therefrom, the shaft having a generally polygonal cross-section and the faces of the shaft carrying a series of barbs having an arcuate edge, wherein the exterior profile of the barbs is slightly greater than the interior diameter of the cylindrical cavity, and the polygonal cross-section shaft is a close fit within the cylindrical cavity.

2. The fixing according to claim 1 wherein the shaft is of square cross section.

3. The fixing according to claim 1 wherein each face of the shaft comprises a flat strip adjacent each edge of the face and a raised rib between them.

4. The fixing according to claim 1 wherein the barbs extend substantially across the entire width of each face of the shaft.

5. The fixing according to claim 1 wherein the barbs are shaped like a flat geometrical segment of a circle on one side and have a frusto-conical or generally convex shape on the other side of the barb.

6. The fixing according to claim 1 wherein the head portion forms a stud, comprising a cylindrical or slightly conical section of external diameter slightly greater than the diameter of the polygonal section shaft and a cap, the underside of which is annular in a plane perpendicular to the elongation of the shaft and the top being conical, domed or frusto-conical.

7. The fixing according to claim 1 further comprising a central axial hole through which a secondary fastener may be passed.

Description

[0019] By way of example, a fastener in accordance with the present invention is illustrated in the accompanying drawings in which:

[0020] FIG. 1 is a perspective view of a fastener in accordance with the present invention;

[0021] FIG. 2 is a side view of the fastener shown in FIG. 1;

[0022] FIGS. 3 and 4 are end views of the fastener, FIG. 3 being from the dowel portion end and FIG. 4 being of the head;

[0023] FIG. 5 is a longitudinal section of the fastener along the lines 5-5 in FIG. 2; and

[0024] FIG. 6 is a cross-sectional view along the lines 6-6 in FIG. 5.

[0025] Referring to the drawings, the dowel fastener according to the present invention illustrated in them consists basically of a dowel portion 1 and a head portion 2. The dowel portion 1 consists of a square section shaft 3 having on each of its four faces a set central low profile convex rib and of four moulded barbs 4. As can be seen most clearly in FIG. 6, the barbs 4 extend outwards from the square section shaft 3 so that they have an external size greater than the diagonal measurement between two corners of the shaft 3. The end of the shaft 3 has a circular, part frusto-conical cap 6. The frusto-conical shape means that the fastener may be positioned slightly extending into a pre-drilled hole before being inserted into that hole, e.g. using a hammer or mallet.

[0026] The head portion 2 is formed of a cylindrical section 8 and an end cap 9. The diameter of section 8 is slightly larger than the overall size of the dowel portion 1 so as to form a shoulder 10 which, when the fastener is inserted into the pre-drilled hole, abuts the surface of the material in which the hole is drilled.

[0027] The fastener illustrated has a central bore 12 through which a long woodscrew may be passed if it is desired, once the fastener has been inserted into a furniture component, to anchor it even more firmly against being pulled out from that component. The surface of the central low profile convex ribs is concentric with the axis of the dowel portion, as can be seen most clearly in FIG. 6.

[0028] The dimensions shown on the drawings are in millimetres, and as can be seen the particular fastener shown is designed to be inserted into a hole of 7 mm internal diameter.