GB2085542A

GB2085542A - Fasteners for plastics panels

Info

Publication number: GB2085542A
Application number: GB8131264A
Authority: GB
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 1980-10-17
Filing date: 1981-10-16
Publication date: 1982-04-28
Also published as: DE3137734A1; ES260818U; FR2492481A1; CA1161673A; SE8105742L; ES506317A0; AR227443A1; ES8301335A1; ES260818Y; IT1139231B; IT8124523A0; AU7389981A; BR8105364A

Abstract

A sheet metal clinch nut 10, plastics panel 20, and fastener 34 assembly is characterised in that the nut includes a flat portion 12 having a first aperture 14 with protrusions 16 and a body portion 18 having a second aperture 26 aligned with the first aperture 14; the plastics panel 20 has a portion 32 extending through the first aperture so as to fix the clinch nut axially and rotationally to the panel; and the threaded shank of the fastener 34 is of a length and diameter to enable member 36 to be fastened to panel 20. Other forms of nut for use with the plastics panel are described e.g. see Figs. 6, and 1. <IMAGE>

Description

SPECIFICATION Clinch nuts for plastic panels The present invention is directed to sheet metal clinch nuts particularly adapted for being secured to plastics panels. Some of the nuts are developments of those described in our British Patent Application No. 8103432 (Serial No.

2 069 088).

While clinch nuts in Application No. 2 069 088 are for attachment and use with thin metal panels, the clinch nuts of the present invention are for thin plastics panels. An example where a clinch nut of the present invention can be particularly suited for use is in the liners for refrigerators. The interior liner or wall of the refrigerator is a one piece plastics member, which can be vacuum formed, for example. The liner is inserted and attached to the refrigerator casing and then insulation is foamed-in-place between the inner and outer walls. Subsequently, shelf and drawer supports, light fixtures and other accessories must be affixed to the interior of the liner. Some type of metal fastening member is necessary to backup the plastics so as to distribute the load and prevent a fastener from pulling out of the plastics.

Conventional clinch nuts, and even those of Application 2 069 088, require the panel to be punctured to effect attachment to the panel. Such throughbores are clearly undesirable in an application such as this, since the foamed insulation would seep through these holes into the refrigerator compartment and not be retained between the two walls.

The present invention overcomes these deficiencies in prior art clinch nuts by providing an inexpensive, sheet metal nut which can be affixed to a thin plastics panel without the need for piercing the plastics.

The invention relates principally to a combination of a sheet metal clinch nut, a plastics panel, and a fastener with a threaded shank; the nut including a flat portion having a first aperture through the flat portion and protrusions extending from the flat portion into the first aperture, and a body portion integrally connected with the flat portion and offset from the plane of the flat portion so that a recess is defined between the protrusions and the body portion, there being a second aperture through the body portion, aligned with the first aperture; the plastics panel having one side abutting the side of the flat portion opposite the body portion, and having a portion extending from the plastics panel among the protrusions and into the recess to as to fix the clinch nut axially and rotationally to the panel member; the threaded shank of the fastener being of sufficient length to extend through the plastics panel and its extending portion and through the second aperture, and of a diameter such as to make threaded engagement with at least a portion of the periphery of the second aperture.

A sheet metal clinch nut as defined above may be attached to a plastics panel by a method comprising supporting the nut adjacent to one side of the plastics panel, and deflecting a portion of the panel towards the nut so that the plastics material flows between and around the protrusions into the recess.

In certain embodiments, the body portion of the nut is of convex/concave shape, integrally joined at its outer periphery to the flat portion, and the protrusions are deflected out of the body portion.

Apparatus for attaching such a nut to a plastics panel may comprise a first male die member and a second female die member, the male die member having a projection with a lateral dimension less than that of the space defined by the protrusions, said female die member having a pocket of sufficient size and shape to accommodate said body portion, a set of inwardly extending ribs having a pattern identical to that of said protrusions, each of said ribs having a width and length which is less than that of its respective protrusion so as not to impede free flow of the plastics material between and around the protrusions during attachment.

The panel need not be punctured, which makes the invention especially useful in applications such as that previously noted. Of course, the present invention may be used in other applications where piercing of the panel is not important or is unavoidable.

The accompanying drawings show various embodiments of the invention, by way of example.

In these drawings: Fig. 1 is a top view of the clinch nut of a first embodiment; Fig. 2 is a bottom view of the clinch nut shown in Fig. 1; Fig. 3 is a cross-sectional view taken along line 3-3 of Fig. 1, showing the clinch nut being assembled to a plastics panel; Fig. 4 is a cross-sectional view similar to Fig. 3 showing the clinch nut with a fastener attaching a shelf bracket to the plastics panel; Fig. 5 is a bottom view of a clinch nut of a second embodiment; Fig. 6 is a cross-sectional view taken along line 6-6 in Fig. 5 showing the clinch nut assembled to the panel; Fig. 7 is a top view of a clinch nut of a third embodiment; Fig. 8 is a cross-sectional view taken along line 8-8 in Fig. 7 showing the clinch nut assembled to the panel; Fig. 9 is a top view of a clinch nut of a fourth embodiment;; Fig. 10 is a cross-sectional view taken along line 10-10 in Fig. 9 showing the clinch nut assembled to the panel; Fig. 11 is a schematic top view depicting a method of feeding a strip of interconnected clinch nuts; Fig. 12 is a top view of a clinch nut of a fifth embodiment; Fig. 1 3 is a cross-sectional side view depicting the clinch nut of Fig. 12 being assembled to the plastics panel, as would be seen from along line 13-13 in Fig. 12.

Fig. 14 is a top view of the female die member used in the Fig. 1 3 assembly; and Fig. 1 5 is a sectional view of the Fig. 12 clinch nut assembled to the panel, as would be seen along line 1 5-15 in Fig. 12.

A clinch nut for a first embodiment of the present invention is depicted in Figures 1 to 4 generally at 10. A first or upper, generally planar flat portion 12 is adapted to be positioned adjacent to a plastics panel 20, e.g. part of a refrigerator liner. This portion 12 has an aperture 14 extending therethrough with a plurality of protrusions in the form of teeth 1 6 projecting inwards. A substantially planar body portion 1 8 extends generally parallel to the portion 1 2 and is interconnected thereto by portion 22. The portions 12 and 1 8 are spatially separated and this separation is maintained by a plurality of bumps 24 which are punched out of the portion 12.A second aperture 26 is formed in the body portion 1 8 along the innermost edge of a volute section 28 which is pushed out of the plane of the body portion 18.

As seen in Fig. 3, the clinch nut 10 is positioned and supported beneath the plastics panel 20 in the position desired. A punch 30 is then brought into contact with the upper surface of the panel (as seen in Fig. 3), and is driven a distance somewhat greater than the thickness of the panel, thus extruding the plastics material downwards through the aperture 14, to form an extended portion 32 of the panel. The bumps 24 maintain the nut portions 12 and 1 8 in a spaced condition giving the plastics material a recess into which it can flow. This plastics material flows between and beneath the teeth 16, thus locking the nut 10 to the panel 20 both axially and rotationally. A fastener 34 is inserted subsequently, to attach a shelf support 36 to the panel 20, as shown in Fig. 4.The periphery of aperture 26 is defined by an edge of the sheet metal lying in a helix. This contributes to threaded engagement with the fastener 34.

A clinch nut for a second embodiment of the present invention is shown in Figs. 5 and 6 generally at 10. The clinch nut of this embodiment is made from a singie thickness of sheet metal and may have a circular shape if desired. Teeth 1 6 are maintained substantially in the plane of a flat portion 12 while a body portion 28 is pushed out into a convexiconcave body of volute shape having an aperture 26 the edge of which is helical.

The inner periphery of the flat portion 12 forms the first aperture 14, while the second aperture 26 is, again, formed along the inner edge of volute portion 28. This embodiment functions in a manner similar to that of the Figs. 1 to 4 embodiment.

A clinch nut for a third embodiment is depicted in Figs. 7 and 8 generally at 10. In this embodiment, the flat portion is comprised of two substantially coplanar parts 1 2A and 1 2B.

Aperture 14 and its teeth 1 6 are formed along adjacent edges of these parts 1 2A and 12B, and there are two interconnecting portions 22A and 22B. These two portions make the use of spacing bumps unnecessary for many applications.

A clinch nut for a fourth embodiment is shown in Figs. 9 and 10 generally at 10. It is similar to the previous nut in that it has two interconnecting portions 22A and 22B. However, in this embodiment, it is the second aperture 26 rather than the first aperture 14 which is formed by the adjacent edges of two parts. Moreover the parts are inclined so that, as seen in Fig.10, the recess within the nut is of triangular shape.

Fig. 11 shows a novel method of feeding clinch nuts to be staked. A plurality of clinch nuts 10 are interconnected in a continuous strip by narrow fingers 40. These fingers may have V-notches 42 on one or both sides, the embodiment depicted in Fig. 11 showing notches on the one side only. On the opposite side are a pair of protrusions 44.

The strip of clinch nuts 10 is fed axially by a machine (not shown), such as that described in Application 2 069 088 for example. As the leading nut reaches the staking station 50 it is deflected angularly with respect to and in the same plane as the rest of the nuts in the strip. As shown, the angle of deflection is forty-five degrees, although this angle may be greater or smaller. Protrusions 44 on this and the adjacent nut make contact, ensuring complete breakage of the finger 40. The leading nut 10 is then completely separated and is in position to be staked to a panel as described in the aforementioned application. Although the method has been shown in conjunction with a round clinch nut, of course the method is applicable to clinch nuts of whatever shape desired.

A clinch nut for a fifth embodiment is depicted in Figs. 12 and 13 generally at 10. In this embodiment, the flat portion is a flange 50 extending laterally outwards from a body portion including an extruded cylindrical barrel 52. The barrel defines an aperture 54 and has an internal helical thread 56. The barrel 52 is joined to the flange 50 by a convexiconcave part of the body portion, from which are deflected protrusions in the form of teeth 58. There is a recess defined between the underside 60 of the teeth and the mouth of the aperture 54.

In assembiing this nut 10 to the panel 20, the nut is seated in a female die member 62 beneath the panel. The die 62 has a pocket 64 of sufficient size and shape to accommodate the body portion of the nut 10. The male die member 66 has a projection 68 which has a lateral dimension which is less than the smallest lateral dimension of the space defined by the innermost edges of the teeth 58.

Since the teeth 58 are cut from the body portion and bent upwardly therefrom, the tendency is for the plastics material being moved by projection 68 to collapse the teeth downards towards their original position. This would prevent the necessary flow of the plastics to connect the nut to the panel. For this reason, the female die member 62 has a plurality of ribs 70 extending inwards in the pocket 64 and having a pattern which is identical to that of the teeth 58. Each rib 70 has a lateral and longitudinal dimension less than that of its respective tooth 58. In this manner, the ribs 70 do not entirely inhibit the flow of the plastics material of the panel 20 around any of the sides of teeth 58, as shown in Fig. 1 5.

This embodiment and, in fact, any of the previously disclosed embodiments may also be used in applications where piercing of the panel is either unimportant or unavoidable.

A female die member similar to that shown here may also be used with the embodiment of Figs. 5 and 6. Because of the size and configuration of the body portion in the remaining embodiments, such supporting female die members are unnecessary.

Claims

1. A combination of a sheet metal clinch nut, a plastics panel, and a fastener with a threaded shank; the nut including a flat portion having a first aperture through the flat portion and protrusions extending from the flat portion into the first aperture, and a body portion integrally connected with the flat portion and offset from the plane of the flat portion so that a recess is defined between the protrusions and the body portion, there being a second aperture through the body portion, aligned with the first aperture; the plastics panel having one side abutting the side of the flat portion opposite the body portion, and having a portion extending from the plastics panel among the protrusions and into the recess so as to fix the clinch nut axially and rotationally to the panel member; the threaded shank of the fastener being of sufficient length to extend through the plastics panel and its extending portion and through the second aperture, and of a diameter such as to make threaded engagement with at least a portion of the periphery of the second aperture.

2. A combination according to claim 1, in which the body portion of the clinch nut includes a barrel which defines the second aperture, and in which there are several turns of internal thread.

3. A combination according to claim 1, in which the second aperture is defined by an edge of sheet metal lying in a heiix.

4. A combination according to any of claims 1 to 3, in which the body portion is of convex/concave shape, integrally joined at its outer periphery to the flat portion, and the protrusions are deflected out of the body portion.

5. A method of attaching a sheet metal clinch nut as defined in claim 1 to a plastics panel comprising supporting the nut adjacent to one side of the plastics panel, and deflecting a portion of the panel towards the nut so that the plastics material flows between and around the protrusions into the recess.

6. A method according to claim 5, wherein the deflecting step includes contacting a second side of the plastics panel with a punch and extruding the plastics material into the recess.

7. A method according to claim 6, including supporting the protrusions to prevent collapse by the punch and the plastics material being moved thereby, without completely preventing material movement around any side of any of the protrusions.

8. Apparatus for attaching a sheet metal clinch nut as defined in claims 1 and 4, to a plastics panel, comprising a first male die member and a second female die member, the male die member having a projection with a lateral dimension less than that of the space defined by the protrusions, said female die member having a pocket of sufficient size and shape to accommodate said body portion, a set of inwardly extending ribs having a pattern identical to that of said protrusions, each of said ribs having a width and length which is less than that of its respective protrusion so as not to impede free flow of the plastics material between and around the protrusions during attachment.

9. A combination according to claim 1, substantially as described with reference to Figs. 1 to 4, Figs. 5 and 6, Figs. 7 and 8, Figs. 9 and 10, or Figs. 1 2 to 1 5 of the accompanying drawings.