GB2026083A - Fastener - Google Patents

Abstract

A fastener for attachment to an apertured support, the shank 12 having a central stem 16, a leading end for insertion through the aperture and a plurality of vanes 17, 18, 19 which extend lengthwise of the stem and radially outwardly from the stem, wherein each vane carries at least one resilient lateral flange 20, 20a which is adapted to be deflected radially inwardly when the shank is inserted through the aperture, each flange being bounded by a generally lengthwise extending radially outermost engagement edge 22, 23 adapted to ride on the rim of the aperture during insertion of the shank therethrough. <IMAGE>

Description

SPECIFICATION Fastener The present invention relates to an improved fastener for attachment to an apertured panel.

There is a need, particularly in the automotive industry for a resilient synthetic plastics fastener having a compressible shank which can be readily inserted into an aperture formed in the panel so as to secure the fastener to the panel. In designing a fastener of this type it is necessary to ensure that the shank can be inserted into the aperture easily without any risk of the shank tilting as it is inserted and without damage to the fastener but once in place will resist substantial pullout forces. In many applications it is a requirement that the resistance to removal should be kept within very close limits and with many known designs this is not possible. It is also necessary to take into account the manufacturing cost of the fastener which should be relatively easy to mould and should require a minimum of material.There is also a need for a fastener which will accommodate a substantial tolerance on the diameter of the aperture in which it is to be mounted, inaccuracies in the shape of the aperture and burrs around the rim of the aperture.

It is an object of the present invention to provide a fastener which will meet these requirements.

In one embodiment of the present invention we provide a fastener for attachment to an apertured support, the shank having a central stem, a leading end for insertion through the aperture and a plurality of vanes which extend lengthwise of the stem and radially outwardly from the stem, wherein each vane carries at least one resilient lateral flange which is adapted to be deflected radially inwardly when the shank is inserted through the aperture, each flange being bounded by a generally lengthwise extending radially outermost engagement edge adapted to ride on the rim of the aperture during insertion of the shank therethrough.

Each vane may carry two similar integral flanges extending laterally on opposite sides of the vane or alternatively the vanes may be arranged in pairs positioned symmetrically around the stem.

Preferably, the engagement edges of the flanges associated with each vane or each pair of vanes diverge away from the leading end of the shank and radially outwardly up to a maximum and then converge radially inwardly towards the head thereby forming a pair of shoulders adapted in use to retain the shank within the aperture. The angle of inclination or each engagement edge to the axis of the shank is preferably substantially greater from the shoulder towards the head of the fastener than between the shoulder and the leading end of the shank.

In use the leading end of the shank is inserted through an aperture in a panel in which the fastener is to be mounted until the diverging engagement edges of the flanges contact the rim of the panel aperture. As the shank is inserted further through the aperture, the flanges are deflected radially inwardly so as to compress the shank of the fastener until the shoulders pass through the aperture. The dimension between the shoulders and the head of the fastener in relation to the thickness of the panel is such that, when further insertion of the shank through the aperture is limited by abutment of the head against the outer surface of the panel, the radially inwardly and converging portions of the engagement edges of the flanges engage the rim of the aperture to resist withdrawal of the shank from the aperture.

The resilience of the flanges is sufficient to accommodate a substantial tolerance in the diameter of the aperture in which the fastener can be securely mounted. Preferably, the shank has at least six lateral flanges so that the rim of the aperture as engaged at six spaced points by the engagement edges of the flanges. The shank of the fastener will thus make secure engagement with the rim of the aperture even if the aperture is of an irregular shape or is surrounded by burrs or other projections. The six equally spaced points of engagement between the shank and the rim of the aperture also minimise any risk of the shank tilting or rotating as it is inserted into the aperture.

A preferred form of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is an elevation of a fastener according to the present invention; Figure 2 is an underplan of the fastener shown in Fig 1; Figure 3 is a side elevation, partly in section of the fastener shown in Figs. 1 and 2; Figure 4 is an elevation partly in section showing the fastener of Figs. 1 to 3 mounted in an apertured panel; Figure 5 is a side elevation, partly in section, of a modification of the fastener shown in Figs. 1 to 4; and Figure 6 is an under plan view of the fastener shown in Fig. 5.

In the drawings a fastener according to the present invention is indicated generally at 1 0.

The fastener 10 is formed from a suitable synthetic plastics material such as an acetal resin by injection moulding.

The fastener 10 comprises a head 11 and a shank 1 2. The head 11 comprises an end member 1 3 which is circular, a cylindrical portion 1 4 which is of substantially smaller diameter than the end member 1 3 and a resilient frusto-conical skirt 1 5 which partially surrounds the adjacent portion of the shank 12.

The shank 1 2 has a central stem 1 6 which is generally cylindrical, solid and co-axial with the cylindrical portion 1 4 of the head 11.

Joined to the stem 1 6 are three similar vanes, 17, 1 8 and 1 9 respectively. Each vane 17, 18, 1 9 extends longitudinally and radially from the stem 1 6 and carries two similar, lateral flanges 20, 20aforming a radially outwardly facing dished surface 21 which is bounded by two engagement edges 22 and 23 respectively. The bounding engagement edges 22 and 23 diverge and extend radially outwardly away from the leading end of the shank 1 2 up to a circumferential line 'a' of maximum radial extension. The bounding edges 22 and 23 then converge and extend radially inwardly from the line 'a' towards the head 11 to form shoulders 24.

The fastener 10 can be mounted in a circular aperture 25 in a sheet metal panel 26 as shown in Fig. 4. In order to mount the fastener in the aperture 25, the leading end of the shank 1 2 is inserted through the aperture 25 until the bounding engagement edges 22, 23 of the flanges 20, 20a contact the rim of the aperture 25. As the shank 11 is inserted further into the aperture 25, the flanges are deflected and radially compressed as the bounding engagement edges 22, 23 ride across the rim of the aperture.

The dimension 'b' between the shoulders 24 of the shank and the peripheral surface of the skirt 1 5 is less than the thickness of the panel 26 so that the skirt 1 5 is flattened as the shank is inserted through the aperture. As soon as the shoulders 24 of the shank pass through the aperture, the rim of the aperture on the inner surface of the panel 26 engages the converging and radially inwardly extending portions of the bounding engagement edges 22, 23 of the flanges so that the panel is clamped between the bounding engagement edges and the flattened skirt 1 5. Withdrawal of the shank from the aperture is thereafter resisted by the bounding engagement edges 22, 23 of the flanges.

It will be seen from Fig. 3 that the angle of inclination of the diverging portions of the bounding engagement edges 22, 23 to the axis of the shank is substantially less than the angle of inclination of the converging portions of the bounding engagement edges so that the shank presents substantially less resistance to insertion into the aperture than to withdrawal from the aperture.

The resilience and flexibility of the flanges 20,20a enables the shank to be securely mounted in apertures of substantially different diameters so as to allow a substantial tolerance in the aperture forming operation on the panel. Furthermore, since the rim of the aperture is engaged at six points around the periphery of the aperture, substantial irregularities in the shaping of the aperture as well as burrs or other deformations in the panel around the rim of the aperture can be accommodated without any loss of security. The substantial number of engagement points and their symmetrical position also reduces any risk of the shank tilting as it is inserted. This resistance to removal can be kept within close limits by varying the scope of the engagement edges or the shape and flexibility of the flanges.

The preferred embodiment of the fastener of the present invention is provided, as shown in the drawings, with three vanes 17, 18, 19.

However it is envisaged that there may be specific applications in which it is advantageous to provide more than three similar vanes or alternatively only two vanes.

It is also envisaged that the vanes may be provided in pairs positioned symmetrically around the circumference of the stem, as shown in Figs. 5 and 6. Figs. 5 and 6 illustrate a modification of the fastener shown in Figs. 1 to 4, the modification being indicated in Figs. 5 and 6 and generally at 30.

The fastener 30 comprises a head 31 which is similar in all respects to the head 11 of the fastener 10 and will not therefore be described in any detail. The fastener 30 also includes a shank 32 which has a central, substantially solid stem 33 and a rounded leading end 34.

Joined to the central stem 33 are six similar vanes 35, 36, 38, 39 and 40. The vanes are arranged in pairs which are symmetrically positioned around the circumference of the stem 33.

Each vane carries a lateral flange 41 which has a radially outwardly facing dished surface 42. Each flange 41 is bounded by an engagement edge 43 and the engagement edges 43 of each pair of flanges diverge and extend radially outwardly from the leading end of the shank up to a point of maximum radial extension and then converge and extend radially inwardly towards the head to form shoulders 44.

The fastener 30 is used in the same manner as the fastener 10 and can be mounted in a circular aperture in a sheet panel in the manner described with reference to Fig. 4. As the shank 32 is inserted through an aperture, the lateral flanges of each pair of vanes will be deflected and compressed radially inwardly until the shoulders 44 pass through the aperture whereupon the inwardly converging portions of the engagement edges 43 will locate behind the rim of the aperture so that the panel is clamped between the engagement edges 43 of the flanges and the skirt forming a part of the head 31 of the fastener.

The head 11 of the fastener 10 and the head 31 of the fastener 30 is adapted specifically for attaching a trim pad formed with a keyhole slot to an apertured panel in a manner which is well known in the automotive industry. However, it is envisaged that a fastener according to the present invention may be provided with a head which is adapted to hold a cable or rod or alternatively the fastener of the present invention may be adapted for use as a plug or closure for an aperture.

The flanges of the fastener of the present invention may have bounding engagement edges which extend in parallel with the axis of the shank from the shoulder to the head and these flanges may be joined to the head of the fastener or may terminate short of the head.

It is also envisaged that the flanges of the fastener of the present invention may be substantially flat rather than being dished.

While the preferred material for the fastener of the present invention has been described as an acetal resin it is envisaged that other materials may also be suitable.

Other variations to the fastener of the present invention may also be made without departing from the scope and spirit of the present invention.

Claims (11)

1. A fastener having a head and a shank adapted for attachment to an apertured support, the shank having a central stem, a leading end for insertion through the aperture and a plurality of vanes which extend lengthwise of the stem and radially outwardly from the stem wherein each vane carries at least one resilient lateral flange which is adapted to be deflected radially inwardly when the shank is inserted through the aperture, each flange being bounded by a generally lengthwise extending radially outermost engagement edge adapted to ride on the rim of the aperture during insertion of the shank therethrough.

2. A fastener as claimed in claim 1, wherein the vanes are positioned symmetrically around the stem.

3. A fastener as claimed in claim 1 or claim 2, wherein the fastener is provided with three vanes which are equi-angularly spaced around the stem.

4. A fastener as claimed in any preceding claim wherein each vane carries two similar integral flanges extending laterally on opposite sides of the vane.

5. A fastener as claimed in claim 4, wherein the engagement edges of the flanges associated with each vane diverge away from the leading end of the shank and radially outwardly up to a maximum and then converge radially inwardly towards the head thereby forming a pair of shoulders adapted in use to retain the shank within the aperture.

6. A fastener as claimed in claim 5, wherein the angle of inclination of each engagement edge to the axis of the shank is substantially greater from the shoulder towards the head of the fastener than between the shoulder and the leading end of the shank.

7. A fastener as claimed in any of claims 4 to 6, wherein the integral flanges of each vane are radially outwardly concavely dished.

8. A fastener as claimed in claim 1 wherein the vanes are arranged in pairs positioned symmetrically around the stem.

9. A fastener as claimed in claim 8, wherein the fastener is provided with three pairs of vanes which are equi-angularly spaced around the stem.

10. A fastener as claimed in claim 8 or claim 9 wherein the flanges of each pair of vanes extend laterally in opposite directions.

11. A fastener as claimed in claim 10 wherein the engagement edges of the flanges of each pair of vanes diverge away from the leading end of the shank and radially outwardly up to a maximum and then converge radially inwardly towards the head thereby forming a pair of shoulders adapted in use to retain the shank within the aperture.

1 2. A fastener as claimed in claim 11, wherein the angle of inclination of each engagement edge to the axis of the shank is substantially greater from the shoulder towards the head of the fastener than between the shoulder and the leading end of the shank.

1 3. A fastener as claimed in any of claims 8 to 12, wherein the flanges of each pair of vanes are radially outwardly concavely dished.

1 4. A fastener as claimed in any preceding claim, wherein the stem of the shank is substantially solid.

1 5. A fastener substantially as described herein with reference to Figs. 1 to 4 or Figs.

5 and 6 of the accompanying drawings.