GB2078893A - Fasteners - Google Patents

Abstract

A deformable plastics fastener adapted for reception on a threaded stud S to clamp an article A thereby has a plastics sleeve 10 to engage the stud, a concentric plastics rib 12 to engage the article and a flexible resilient plastics web 14 reinforced by a resilient metal washer 20 bridging the gap between the sleeve and rib and extending into the rib, the web and metal washer being deformed when the sleeve is pushed on to the stud to provide the clamping pressure. The fastener may be released by unscrewing it, holes in the web for engagement by a suitable tool being provided. <IMAGE>

Description

SPECIFICATION Fasteners This invention is concerned with a fastener suitable for holding an article against a surface by cooperation with a stud projecting through a hole in the article; fasteners of this kind include nuts which may be threaded on bolts welded, for example, to the surface and a variety of sheet metal spring clips.

Many fasteners for the foregoing purpose are available, varying in strength, ease of assembly and tightening, economy of production, weight, corrosion resistance, complexity and so on, as well as in their specific performance under particular conditions of heat, humidity, vibration etc. The object of this invention is to provide an improved fastener having a desirable blend of the foregoing factors, especially lightness in weight, ease of handling and assembly, simplicity of construction, economy of manufacture, and satisfactory clamping effect.

Afastenerwhich affords a reliable blend of such factors when used in co-operation with a threaded stud is provided by the present invention in that it comprises a plastics body having a sleeve portion for engagement with the stud, an annular rib concentric with said sleeve portion and spaced therefrom and a flat annular web bridging the gap between the sleeve portion and the rib, an articleengaging face of the rib being axially ahead of the sleeve portion, and the fastener also comprising a flat annular resilient metal washer lying against the web at the same side as the rib and with its periphery extending into the rib, the hole in the washer being slightly larger than the hole in the sleeve, so that when the fastener is advanced along a stud first the rib engages the article and then, on further advance of the sleeve portion, the web and washer are deformed and the rib is resiliently urged thereby towards said surface to clamp the article thereagainst.

Preferably, a stud with which the fastener is used is screw-threaded and the fastener is provided with means to enable it to be unfastened upon rotation by a suitable tool. The sleeve portion or rib, or both, of the fastener may, for this purpose, have a square or hexagonal periphery for engagement by a spanner, or the web may have two or more holes for engagement by a suitably shaped tool. The sleeve portion preferably provides a continuous, smooth inner wall.

The web of a fastener in accordance with the invention preferably joins the leading end of the sleeve portion to a rear end of the rib so that the depth of the rib is available for advance of the sleeve portion after the rib is engaged with the article to cause deformation of the web and washer which gives rise to the clamping pressure. Such a configuration of fastener is one for which it is especially simple to make moulding dies.

Where a fastener in accordance with the invention is to be used with a threaded stud, and its body is made of a thermoplastics polymeric material with the strength and resilience of nylon 66 for example, the sleeve portion is preferably a continuous wall uninterrupted by slits or projections. Nylon 66 is preferred where the fastener may be subject to high temperatures (e.g. 1500C).

The washer of a fastener in accordance with the invention is preferably stainless stell or other noncorrosive metal. The inner wall of plastics material of the body may flare out as a conical surface to meet the inner edge of the washer.

A fastener illustrative of the invention and selected for description by way of example and not of limitation of the invention is shown in the accompanying drawings in which: Figures 1 and 2 are views in plan and diametrical sections respectively of the illustrative fastener; and Figure 3 is a view in section showing the fastener clamping an article to a surface by co-operation with a screw-threaded stud.

The illustrative fastener is a one-piece moulding of nylon 66 with a moulded-in reinforcing washer intended for co-operation with a screw-threaded stud S (Figure 3) welded to the surface of a support Wand projecting through a hole H in an article A to be clamped to the support.

The illustrative fastener comprises a body having a sleeve portion 10 adapted to grip the stud S when it is pushed axially on to the stud. The sleeve portion has a smooth cylindrical internal surface into which the crest of the stud thread presses permitting release of the fastener by an anti-clockwise unscrewing rotation.

Concentric with the sleeve portion of the illustrative fastener is a flat annular rib 12 having an internal diameter more than three times the internal diameter of the sleeve portion. A rear end portion of the rib 12 is joined by a flat annular web 14to a forward end of the sleeve portion 10.

A flat spring stainless steel washer 20 lies against the same side of the web 14 as the ribs 12 and, being pre-assembled in the mould in which the body was made, extends at its periphery into the rib 12. The washer has a hole 22 slightly larger than the inner diameter of the sleeve portion 10, which increases conically towards the inner edge of the washer.

In order to clamp the article A two the support S, the illustrative fastener is pushed on to the stud with a front edge 16 of the rib 12 leading. After the leading edge of the rib has engaged the article, further advance of the sleeve portion 10 along the stud results in deformation of the web 14 and washer 20 (as shown in Figure 3), which deformation increases as the sleeve portion approaches the article. With the sleeve portion then gripping the stud and unable to retract along it, the rib presses against the article due to resilience of the deformed web, thus clamping the article to the support.

The illustrative fastener may be released by unscrewing it, which action may be assisted by a suitable tool. For this purpose, the web may have two holes 18 in it (as shown in Figures 1 and 2) for the engagement by pins of a suitable tool.

Deformation of the web of the illustrative fastener is normally limited by the depth of the rib 12, which has been found to be sufficient to give adequate clamping pressure.

Where the invention has been described with reference to use of the fastener for clamping an article against a surface from which a stud projects, there are other applications where it may be useful.

For example two such fasteners could be used on a threaded shaft to clamp between them a 'member which it is desired to drive frictionally upon rotation of the shaft.

By selection of a washer of appropriate size and yield stress, the maximum ultimate clamping force achieved by the washer can be determined.

Claims (7)

1. A fastener suitable in co-operation with a stud projecting from a surface through a hole in an article for holding the article against said surface, comprising a plastics body having a sleeve portion for engagement with the stud, an annular rib concentric with said sleeve portion and spaced therefrom and a flat annular web bridging the gap between the sleeve portion and the rib, an article-engaging face of the rib being axially ahead of the sleeve portion, and the fastener also comprising a flat annular resilient metal washer lying against the web at the same side as the rib and with its periphery extending into the rib, the hole in the washer being slightly larger than the hole in the sleeve, so that when the fastener is advanced along a stud first the rib engages the article and then, on further advance of the sleeve portion, the web and washer are deformed and the rib is resiliently urged thereby towards said surface to clamp the article thereagainst.

2. A fastener according to Claim 1 in which the sleeve portion has a continuous, smooth inner wall for engagement with a screw-threaded stud.

3. A fastener according to either one of Claims 1 and 2 having means for enabling the fastenerto be rotated by a suitable tool to unfasten it.

4. A fastener according to Claim 3 of which the periphery of the sleeve portion or rib or both is square or hexagonal.

5. A fastener according to Claim 4, the web of which has two or more holes in it.

6. Afastenerfor clamping an article to a support by engagement of a projecting stud substantially as hereinbefore described with reference to the accompanying drawings.

7. An assembly comprising an article clamped against the support by means of a screw-threaded stud and a fastener according to any one of the preceding claims.