Aperture plug

A plug for a panel aperture comprising a plate portion and a plurality of resilient legs which depend from the plate portion and which are shaped to be snap-engagable through the aperture in the panel so that the plate portion is drawn onto the panel thereby at least substantially closing the aperture, wherein the legs are formed by extensions of the plate portion which have been folded back onto the plate portion and then away from the plate portion, whereby the legs project from the plate portion from a position radially inwardly of the periphery of the plate portion leaving the periphery of the plate portion unbroken. The folded portion of each leg is preferably located in a recess in the plate portion so as to lie flush with the undersurface of the plate portion and a sealing member may be provided on the undersurface of the periphery of the plate portion. The sealing member may be a heat softenable plastics material which will harden when heated and cooled to bond the plate portion to the panel in which the plug is mounted.

BACKGROUND TO THE INVENTION 
The present invention relates to a plug for closing an aperture in a panel 
and in particular to a plug for closing and sealing an aperture in a 
panel. 
It is known to provide a plug for a panel aperture comprising a plate 
portion and a plurality of resilient legs which depend from the plate 
portion and which can be snap-engaged through the aperture in the panel so 
that the plate portion is drawn onto the panel and substantially closes 
the aperture. Hitherto, the legs have been partially sheared from the 
plate portion so as to leave gaps in the periphery of the plate portion 
which reduce the effectiveness of the seal achieved by the plug. 
STATEMENT OF THE INVENTION 
According to the present invention a plug for a panel aperture comprises a 
plate portion and a plurality of resilient legs which depend from the 
plate portion and which can be snap-engaged through the aperture in the 
panel so that the plate portion is drawn onto the panel and substantially 
closes the aperture, the legs being formed by extensions of the plate 
portion which have been folded back onto the plate portion and then away 
from the plate portion, so that the legs project from the plate portion 
from a position radially inwardly of the periphery of the plate portion 
leaving the periphery of the plate portion unbroken. 
Preferably, the part of each leg which is folded back onto the plate 
portion is sealed in a recess formed in the plate portion so as to lie 
approximately flush with the surface of the plate portion from which the 
legs project. 
In a further aspect the invention provides a method of sealing an aperture 
in a panel comprising the steps of forming a plug comprising a metal plate 
portion having a substantially uninterrupted periphery and a plurality of 
legs each depending from the plate portion from a position spaced radially 
from the periphery of the plate portion and shaped to be snap-engaged into 
the aperture in the panel, providing a ring of heat flowable sealing 
material on the peripheral surface of the plate portion to form a 
continuous band of sealing material between the periphery of the plate 
portion and the legs, mounting the plug in an aperture in the panel, 
heating the panel to a temperature sufficient to cause the sealing 
material to flow onto any irregularities in the surface of the panel and 
thereby effectively seal the aperture.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIGS. 1 to 3 a metal plug is indicated generally at 10. The plug 10, 
which is formed from thin sheet steel and rendered resilient during 
manufacture, comprises a circular plate 11 and three retaining legs 12, 13 
and 14. The legs 12, 13 and 14 are equi-angularly spaced around the 
periphery of the plate 11 and each leg includes an outwardly inclined 
retaining portion 15 and an inwardly inclined lead-in portion 16. 
The legs 12, 13 and 14 are similar to each leg is formed from a tongue 17 
(shown in broken lines in FIG. 1) which is formed integrally with the 
plate 11 and folded back onto the plate 11 to form a fold 18 from which 
the respective leg projects at right angles and outwardly from the plate 
11. A depression 19 is formed in the plate 11 to receive the fold 18 of 
each tongue so that the outer surface of the fold is flush with adjacent 
surface of the plate. As can be seen from FIG. 1 the legs 12, 13 and 14 
are spaced inwardly from the periphery of the plate 11 so as to leave a 
continuous annular surface 20 around the periphery of the plate. 
The metal plug 10 can be used, as shown in FIG. 3 to close a circular hole 
21 in a panel 22. In use, the annular surface 20 is drawn against the 
outer surface of the panel 22 by the retaining portions 15 of the legs so 
as to seal the hole adequately for many purposes, for instance it can 
provide an adequate dust seal. The configuration of the legs also enables 
the plug to withstand considerable pressure. 
If, however, a better seal is required, then a ring seal of resilient or 
deformable material can be added to form a plug 10a as shown in FIGS. 4 to 
6, which incorporates a ring seal 23 formed from a polyvinylchloride based 
compound such as that sold by W. G. Grace & Co. as PLASTICOL Compound No. 
1268. 
A layer of the polyvinylchloride based compound is applied to the annular 
surface 20a of the plug 10a and the compound is cured so as to bond the 
layer to the plate 11a and form the ring seal 23 which is bonded to the 
plate 11a around the legs 12a, 13a and 14a. 
The plug 10a is then applied to an aperture 24 in a panel 25, as shown in 
FIG. 6, with the legs 12a, 13a and 14a projecting through the aperture and 
the rim of the aperture clamped between the inclined retaining portions 
15a of the legs and the ring seal 23. 
We have found that a suitable polyvinylchloride based compound such as 
PLASTICOL 1268 can be cured at about 160.degree. C for 1 to 2 minutes so 
as to bond effectively on the plate 11a. When cooled it becomes non-tacky 
and has sufficient resilience to form a good seal against a panel aperture 
taking up surface irregularities. It will subsequently withstand 
temperatures of up to 250.degree. C and when re-heated it will soften 
slightly but will not melt or become tacky. 
The plug 10a incorporating the sealing ring 23 has been found satisfactory 
in most conditions where the surface irregularities in the panel are not 
too great. If either of these conditions are present then we have found it 
advantageous to form the sealing ring from a material such as a low 
density polythene which will flow when heated so as to fill all the 
surface irregularities of both the panel and the plate portion of the 
plug. An example of a plug 10b having a sealing ring 26, which is formed 
from a low density polythene is shown in FIG. 7. 
The sealing ring 26 is preferably injection moulded, although it can be 
blanked from sheet material, and comprises an annular sealing portion 27, 
a web 28 which is of slightly smaller internal diameter than the diameter 
of the plate 11b, and a retaining rib 29. The ring 26 is stretched and 
fitted on the plate 11b where it is retained by the rib 29 with the 
sealing portion 27 located on the annular surface 20b of the plug. 
The plug 10b can be transported and handled with the ring 26 located in 
position by the resilience of the material and by the retaining rib 29. In 
use, the plug 10b is applied to an aperture 30 in a panel 31, in the same 
way as the plug 10 or the plug 10a so that the sealing portion 27 
surrounds the panel aperture 30 and is trapped between the panel 31 and 
the plate 11b. The panel and the plug 10b are then subjected to a 
temperature sufficient to soften the polythene causing it to flow. As the 
polythene material softens and flows it fills all of the surface 
irregularities of the panel 31 and of the plate 11b and also bonds to both 
the panel and the plate as shown in broken lines in FIG. 7 so as to form a 
water-tight seal. 
The plug 10b is particularly useful for sealing apertures in vehicle body 
panels. In such an application, the plug is located in the body panel with 
the ring 26 loosely fitted on the plate 11b and the body panel and plug 
are then passed through a vehicle paint oven where they are subjected to 
temperatures of 140.degree. C-170.degree. C or more. The temperature of 
the paint oven causes the polythene material of the ring 26 to flow 
filling irregularities in the panel surface and then bond to the panel and 
plate as it cools. 
It will be appreciated that the sealing ring 26 can be attached to the 
plate portion of the plug in any convenient manner prior to heating and 
the shape of the sealing ring can also be modified. For instance, the rib 
29 could be eliminated and the resulting sealing ring temporarily adhered 
to the plate portion prior to heating. Alternatively, the sealing ring can 
be attached to the plate portion of the plug with the aid of prongs, 
sheared from the plate portion. 
It will also be appreciated that the material from which the sealing ring 
is formed can be varied and will be suited to the particular conditions 
under which the plug is used. 
The number of legs provided on any of the plugs of the present invention 
can be varied, for instance, two or more legs can be provided to suit the 
particular application in which the plug is to be used. In addition, the 
shape of the plate portion of the plug can be varied, for instance, it can 
be externally oval, square or elongate and can also be curved to fit a 
curved surface.