GB2151294A

GB2151294A - Stud and socket fastening

Info

Publication number: GB2151294A
Application number: GB08427529A
Authority: GB
Inventors: Jean-Luc Rene Georges Klein
Original assignee: TRW Carr France SAS
Current assignee: TRW Carr France SAS
Priority date: 1983-10-31
Filing date: 1984-10-31
Publication date: 1985-07-17
Also published as: FR2554183A1; GB2151294B; GB8427529D0; DE3339513A1; FR2554183B1; DE3339513C2

Abstract

A socket for cooperating with a screw-threaded stud has an umbrella-shaped head 12 mounted on a cylindrical bore 14 profiled on the inside in the form of ribs 26 which are situated opposite one another, are vertically staggered, and extend from the inner wall of the member 3 towards the centre. The effect of these ribs is that little force is required for applying the stud while considerable force is required for its removal. <IMAGE>

Description

SPECIFICATION A fastener for attachment to a screw threaded stud This invention relates to a fastener and relates particularly but not exclusively to a plastics fastener adapted to be mounted on a screw threaded stud thereby to fasten a sheet member to.a support.

A known fixing element disclosed in DE-GM 1 743 435 is in the form of a plastics nut having an umbrella-shaped head contiguous with a bolt receiving member having internal profiling. The internal profiling is in the form of a continuous internal screw thread, whereby a screwbolt which is attached to a support and extends into an aperture in a sheet member placed on top of the support can be screwed into this thread. As a result of this operation the umbrellashaped head bears against the sheet member thus attaching it to the support. A disadvantage of this sytem is that installation takes a long time because of the necessary screwing motion. Furthermore, this arrangement is insecure since the screw thread of the plastics fixing element can undesirably work loose or can be damaged, for example by jarring against a metal bolt.

The object of the present invention is to provide a fastener for attachment to a screw threaded stud which at least partially overcomes the problems outlined above.

According to the present invention we provide a fastener comprising a generally cylindrical bore comprising at least one open end configured for pushfitting onto a screw threaded stud so as to mount the fastener on the stud wherein the inner wall of the bore is provided with at least two circumferentially spaced retaining elements wherein the at least two retaining elements are offset lengthwise of the bore.

An advantage of a fastener according to the present invention is that it can be push-fitted onto a screw threaded stud using a relatively small amount of force whereas, once applied to the stud, a greater pulling force is required to detach the fastener from the stud. This is because, as the fastener is being pushed onto a stud, the retaining members are successively deformed so as to pass over the turns of the screw-thread on the stud and thereafter wedge in between or on the turns of the screw-thread so that a relatively large pull-off force is required to dislodge the retaining members from the studs.

Another advantage is that the retaining members themselves deform resiliently to accommodate a screw threaded stud within the bore thus obviating the need for the walls of the bore to deform during insertion of a stud.

Consequently, the push-on force required to mount the fastener on a stud is reduced.

The fastener according to the present invention is particularly suitable for use with a coarse-thread stud enabling rapid and easy attachment of the fastener to the stud but with a substantial pulling force being required to remove the fastener from the stud.

A fastener according to the present invention also has the advantage of being rousable by virtue of the retaining members being able to be removed from a stud simply by rotating the fastener so as to unscrew it from the stud.

Preferably, the retaining members are situated generally opposite one another.

In a particular embodiment, the bore is provided with a plurality of circumferentially spaced series of resiliently deformable retaining elements defining a stud receiving channel wherein the retaining elements in each series are spaced lengthwise along the bore and the retaining elements in a first one of the series are offset lengthwise of the bore in relation to the retaining elements in a second one of the series. Offsetting the retaining elements in the different series has the advantage of reducing the push-on force required to mount the fastener on a screw threaded stud because neighbouring offset retaining members are deformed successively rather than simultaneously during mounting of the fastener.Preferably, the retaining elements in the first and second series are likewise equally spaced and the retaining elements in the first series are positioned generally centrally of the gap between the lengthwise nearest pair of retaining elements in the second series.

In a particular embodiment, the spacing between the retaining elements in the first and second series is equal to twice the potential lengthwise deformation of each retaining member. If, for example, the distance between adjacent retaining members in each series is 1.6 mum, then the even staggering of the retaining members means that there is in effect 0.8mm spacing between a retaining member and its closest lengthwise neighbour.

If, furthermore, each retaining member can be deflected by up to approximately 0.8mm this means that a continuous range of mounted positions of the fastener on a threaded stud is available. In practice, if the fastener is to be used to attach a sheet member to a support.

this feature means that a continuous range of sheet thicknesses can be accommodated.

In a particular embodiment, the fastener comprises two diametrically opposed series of retaining elements.

Preferably, the innermost edges of the retaining members define a generally oval channel within the bore.

This feature provides that different parts of each rib may be stressed unequally during insertion thus reducing the push-on force required to attach the fastener to a stud. Furthermore, this feature permits variation in the degree of wedging exerted by different parts of a single retaining member on the stud.

In a particular embodiment, the retaining members are flat ribs extending generally perpendicularly relative to the wall of the bore.

Preferably, with regard to the two circumferentially spaced side edges of each rib, one side edge extends radially of the bore and the other side edge extends at an acute angle to the inner wall of the bore. This shaping is a consequence of the particular slidable core member used in moulding. Advantageously, the acute angled end of each rib is more flexible than the other end of each rib.

In a particular embodiment, the fastener comprises a shank including the bore wherein the side walls of the shank comprise through apertures communicating with the bore so as to increase the deformability of the fastener during push-fitting on a stud. The apertures may extend along a major part of the length of the bore. Preferably, the shank comprises two opposed apertures.

According to a second aspect of the present invention we provide an assembly comprising a screwthreaded stud attached to a support, an apertured sheet member placed on the support so that the stud extends into an aperture in the sheet member and a fastener as described above in the form of a pushbutton fastener and comprising a head contiguous with a shank comprising the bore and which is push-fitted onto the stud so that the shank surrounds the stud in the aperture and the head abuts the sheet member thereby to fasten the sheet member to the support.

The assembly may comprise a sheet member in the form of an insulating mat and a support in the form of an end wall of a vehicle engine compartment. Accordingly, rapid and easy fitting of the insulating mat to the end wall can be achieved using the present invention.

Preferably, the stud receiving channel in the bore in the push-button fastener is smaller in cross-section than the core of the stud. This feature ensures that the retaining members are deflected and stressed during fitting on a stud and subsequently wedge against the core of the stud thereby securely to retain the fastener on the stud.

A particular embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1 is a side elevation of a fastener according to the present invention; Fig. 2 is a side elevation in section of part of an assembly according to the present invention; Fig. 3 is a bottom view of the fastener shown in Fig. 1; Fig. 4 is a section taken on the line IV-IV in Fig. 3 (which changes direction at a centre point Z).

Fig. 1 illustrates a plastics fastener in the form of a push-button fastener 1 0. The fastener comprises an umbrella shaped head 1 2 attached to a hollow cylindrical shank 14. The shank 14 defines an open ended cylindrical bore 1 6 having an entry section 1 7 and is formed with two opposed through apertures 1 8 and 20 which extend along a major part of the length of the bore 1 6.

Figs. 1 and 4 show that the openings 18 and 20 situated opposite one another in the shank 14 extend from the underside of the umbrella-shaped head 1 2 down to the top of the entry section 1 7.

On the inside wall of the bore 1 6 there are two series 22 and 24 of the retaining members in the form of flat inwardly extending ribs 26. The series 22 and 24 of ribs 26 are situated opposite one another and the ribs in series 22 are staggered vertically in relation to the ribs in series 24.

The top of the umbrella-shaped head 1 2 is formed with a slot 28 for engagement with a screwdriver.

Figs. 3 and 4 show the stud 10 in greater detail. Referring to Fig. 3, the innermost edges 30 of opposed ones of the ribs 26 define an oval stud-receiving channel 31 in the bore 16. The side edge 32 of each of the ribs 26 extends radially of the bore whereas the other side edge 34 of each of the ribs 26 extends at an acute angle to the inner wall 10 of the bore 1 6. Thus the acute angled end of each rib 26 is more flexible than the other end.

Referring now to Fig. 4, the vertical gap between adjacent ribs 26 in each of the series 22 and 24 is 1.6mm. Since the two series 22 and 24 of ribs 26 are staggered there is in effect 0.8 mm gap between a rib and its closest opposite neighbouring rib 26. Each of the ribs 26 can be deflected by approximately 0.8 mm so that a continuous range of attachment positions of the fastener 10 on a stud is possible.

The entry section 1 7 of the shank 1 4 is formed with a circular aperture 26 which is smaller than the cross-sectional area of the cylindrical inner wall of the bore 1 6 but larger than the stud-receiving channel 30 defined by the innermost edges of the ribs 26.

The circular aperture 36 is at the top of a conical lead-in portion 38 which, together with the circular aperture 36 provides for more reliable introduction of a stud into the interior of the bore 1 6.

Fig. 2 shows an insulating mat 40 placed on a support 42 to which is attached a screw threaded stud 44. The mat 40 has an aperture 46 through which the stud 44, which has a coarse screw thread extends.

To secure the mat 40 to the support 42 satisfactorily, the fastener 10 shown in Figs.

1, 3 and 4 is positioned so that the shank 14 is aligned above the stud 44 and the uppermost end of the stud 44 is located in the conical lead-in portion 38. The fastener 10 is then pushed downwardly onto the stud 44 until the underside of the head 1 2 abuts the mat 40 thus securing the mat 40 to the support 42.

As the fastener 10 is pushed onto the stud 44, the ribs 26 are deflected upwardly as they are pushed past the turns of the coarse thread on the stud 44. The openings 1 8 and 20 in the walls of the shank 14 permit some outward deformation of the series 22 and 24 of the ribs 26 to accommodate the stud 44 if necessary. When the fastener 10 has been mounted on the stud 44, the ribs 26 engage on and between the screw threads on the stud 44. The oval shape of the stud receiving channel 31 is configured so that at least a part of the ribs 26 wedge against the core of the stud 44.

Due to the configuration of the ribs 26 in the bore 1 6 therefore, the fastener 10 can be attached quickly and simply to the stud 44 using a relatively small push-on force. However, a relatively large pulloff force will be required to pull the fastener 10 off the stud 44 due to the interengagement of the ribs 26 with the screw thread of the stud 44.

The fastener 10 can be removed from the stud 44 by engaging a screw driver with the slot 28 formed in the head 1 2 and screwing the fastener in the appropriate direction so as to screw it off the stud 44. In this way, the fastener 10 can be reused many times.

When the fastener 10 is mounted on the stud 44, the relatively large head 1 2 abuts the mat 40 thereby preventing any tilting movement of the shank 1 4 on the stud 44.

The relatively large size of the head 1 2 also serves to grip a correspondingly large surface area of the mat 40 against the support 42.

Since the ribs 26 in the two series 20 and 24 are vertically staggered relative to one another, this increases the range of positions along the length of the stud 44 which the ribs 26 can occupy so that a continuous range of thicknesses of the mat 40 can be accommodated.

It will be appreciated that the fastener according to the present invention may be incorporated in various types of fasteners other than the push-button fastener described above. For example, a pipe clip may be provided with a fastener according to the present invention to enable it to be attached to a screw threaded stud protruding from a support and many other uses are envisaged. In fact, the present invention is applicable wherever it is desired to attach an article to a screw threaded stud.

Claims

1. A fastener comprising a generally cylindrical bore comprising at least one open end configured for push-fitting onto a screw threaded stud so as to mount the fastener on the stud wherein the inner wall of the bore is provided with at least two circumferentially spaced retaining elements wherein the at least two retaining elements are offset lengthwise of the bore.

2. A fastener according to claim 1 wherein the at least two retaining members are situated generally opposite one another.

3. A fastener according to claim 1 or claim 2 wherein thebore isprovidedwith a plurality ofcircumferentially spaced series of resiliently deformable retaining elements defining a stud receiving channel wherein the retaining elements in each series are spaced lengthwise along the bore and the retaining elements in a first one of the series are offset lengthwise of the bore in relation to the retaining elements in a second one of the series.

4. A fastener according to claim 3 wherein the retaining elements in the first and second series are likewise equally spaced and the retaining elements in the first series are positioned generally centrally of the gap between the lengthwise nearest pair of retaining elements in the second series.

5. A fastener according to claim 4 wherein the spacing between the retaining elements in the first and second series is equal to twice the potential lengthwise deformation of each retaining member.

6. A fastener according to any of claims 3-5 comprising two generally diametrically opposed series of retaining members.

7. A fastener according to any of claims 3-6 wherein the gap between adjacent retaining members in a series is twice the potential lengthwise deformation of each retaining member.

8. A fastener according to any preceding claim wherein the innermost edges of the retaining members define a channel of generally oval section within the bore.

9. A fastener according to any preceding claim wherein the retaining members are flat ribs extending generally perpendicularly relative to the length of the bore.

10. A fastener according to claim 9 wherein, with reference to the two circumferentially spaced side edges of each rib, one side edge extends radially of the bore and the other side edge extends at an acute angle to the inner wall of the bore.

11. A fastener according to any preceding claim wherein the open end of the bore comprises a circular aperture which is smaller than the cross-sectional area of the bore but larger than the cross-sectional area of the channel defined by the retaining members.

1 2. A fastener according to any preceding claim wherein the open end of the bore comprises a conical lead-in portion.

1 3. A fastener according to any preceding claim comprising a shank including the bore wherein the side walls of the shank comprise through apertures communicating with the bore so as to increase the deformability of the fastener during push-fitting on a stud.

14. A fastener according to claim 1 3 wherein the apertures extend along a major part of the length of the bore.

1 5. A fastener according to claim 13 3 or claim 14 wherein the shank comprises two opposed apertures.

1 6. A fastener according to any preceding claim in the form of a push-button fastener comprising a head from which a shank com prising the bore extends.

1 7. A fastener according to claim 1 6 wherein the head comprises screw driver en gaging means to enable the fastener to be screwed-off a stud.

18. A fastener comprising a generally cylin drical bore comprising at least one open end configured for push-fitting onto a screw threaded stud so as to mount the fastener on the stud wherein the inner wall of the bore is provided with a plurality of circumferentially spaced series of resiliently deformable retain ing elements defining a stud receiving channel wherein the retaining elements in each group are spaced lengthwise along the bore.

19. A fastener substantially as herein de scribed with reference to and as illustrated in the accompanying drawings.

20. An assembly comprising a screw threaded stud attached to a support, an aper tured sheet member placed on the support so that the stud extends into an aperture in the sheet member and a push-button fastener as claimed in claim 1 6 push-fitted onto the stud so that the shank surrounds the stud in the aperture and the head abuts the sheet mem ber thereby to fasten the sheet member to the support.

21. An assembly according to claim 20 I wherein the stud receiving channel in the bore .in the push-button fastener is smaller in cross section than the core of the stud.

22. An assembly substantially as herein described with reference to and as illustrated in the accompanying drawings.