An improved plug for an aperture such as the paint drain hole in an automotive body comprises an integral flat body having two opposed aligning protuberances and two opposed engaging protuberances formed adjacent the edge of the body. At least one engaging protuberance is angled radially outwardly and has sufficient spring qualities to allow a snap mount of the plug into the aperture.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
This invention relates to an improved plug having at least one finger means 
for retaining the plug in an aperture in a workpiece. 
(2) Discussion of the Prior Art 
Closure devices, such as impact or bang plug assemblies, are known in the 
prior art for engaging a workpiece to close or seal an aperture formed 
therein. A typical application for a bang plug is to close circular 
openings in the sheet metal of an automobile underbody, which openings 
were cut so that excess paint residue could drain out through the openings 
when the entire body was dipped in a paint bath. 
U.S. Pat. No. 4,634,018 to Becker discloses one impact plug assembly. Other 
closure assemblies are shown in U.S. Pat. No. 4,091,962 to Van Buren, Jr.; 
U.S. Pat. No. 3,990,604 to Branett et al.; U.S. Pat. No. 3,994,107 to 
Wallace et al.; and U.S. Pat. No. 4,391,384 to Moore, III et al. 
SUMMARY OF THE INVENTION 
An improved plug is provided for engaging a workpiece to close an apertures 
therein. The plug of the present invention comprises a relatively thin, 
substantially planar shaped body with no openings extending therethrough. 
The body has formed at the perimeter thereof a number of protuberances for 
engaging the aperture sidewalls and aligning the body with respect to the 
apertures. In addition to providing an alignment function, at least one of 
the protuberances comprises a finger that is angled in a radially outward 
direction to lockingly engage the workpiece in the region of the aperture 
sidewall to restrain the plug from being pulled or displaced out of the 
aperture once it is installed. The finger can be bent by a bending tool to 
so engage the sidewall. The body, including the finger, can also be formed 
of a material having a sufficient spring constant to permit flexing while 
popping or snapping the plug into position; thereafter, the exertion of a 
radially outward force as a result of spring loading inherent in the body 
and finger material retains the plug in place. 
It is an object of the present invention to provide an improved plug having 
no crossbar. 
It is a further object of the present invention to provide an improved plug 
having no holes in the plug itself. 
It is a further object of the present invention to provide an improved plug 
wherein the plug is only one skin thick and there is no seam to seal. 
It is a further object of the present invention to provide an improved plug 
that can be inserted and sealed into an apertures in a workpiece with ease 
and with minimal striking or banging of the plug. 
It is a further object of the present invention to provide an improved plug 
that can be easily installed using a ring seal. 
Further objects and advantages of the present invention will become 
apparent from the following description of the drawings and preferred 
embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As seen in FIGS. 1 and 2, the improved plug 10 of the present invention 
comprises a plug 12 having a number of protuberances described in detail 
below. Plug 12 is generally stamped or pressed from a sheet of metal such 
as 1010 steel and may be treated by galvanizing to prevent corrosion, 
although the plug may also be formed of other materials such as aluminum. 
Plug 12 is preferably a unitary piece with no seams or apertures in the 
plug body. 
Plug 12 is a preferably a round or oval shaped body and is substantially 
planar. 
As shown in FIG. 2, plug 12 can be of any chosen size of diameter to fit 
into and seal a correspondingly shaped and sized aperture in a workpiece. 
It is understood, however, that any shaped plug corresponding to any 
shaped aperture can in principle be used consistently with the present 
invention. 
As further seen in FIG. 2, a typical workpiece for receiving the improved 
plug 12 of the present invention is a section of sheet metal with an 
aperture cut therein, such as an automobile body with a paint drain hole. 
FIG. 2 depicts a workpiece 14 of a chosen thickness generally having an 
outer surface 16 and an inner surface 18. It is understood that the terms 
"inner" and "outer" are used for convenience only and are not intended to 
limit the scope of the present invention. 
An apertures 20 passes through the workpiece 14, the aperture 20 being 
defined by at least one boundary or sidewall 22. If the aperture 20 is 
other than round or oval, such as for example rectangular, it may be said 
to have more than one sidewall. Sidewall 22 joins inner surface 18 along a 
region denoted as an inner rim or juncture 24, which extends all the way 
around the aperture 20. 
As shown in FIG. 1, one preferred embodiment of the present invention 
includes a plug 12 comprising a relatively thin, substantially 
planar-shaped body 26 defined by a perimeter 28. Perimeter 28 is of a 
sufficient magnitude to permit body 26 to completely cover a corresponding 
aperture 20 for which it is intended. 
Body 26 has no openings therethrough, even through a variety of depressions 
28, 30, 32, and 34 therein form the structure for aligning the body 26 and 
retaining body 26 in the aperture 20. The fact that the plug 12 of the 
present invention has no holes therein is advantageous over the prior art, 
because the slots necessary for the prior art crossbar lever may provide 
an opening for dirt, gases, or other contaminants to pass through. For 
example, in the automobile industry it is particularly desirable that 
holes in the sheet metal body be sealed as thoroughly as possible to keep 
out noxious fumes from the engine and the roadway. 
Body 26 has a first side 36 for facing away from aperture 20 and a second 
side 38 for facing toward aperture 20. Second side 38 abuts workpiece 14 
in the regions 40 adjacent aperture 20. 
Body 26 further comprises a flange 42 extending adjacent to and around the 
perimeter 28 of body 26. Flange 42 further forms a groove 44 open to the 
second side 38 of body 26. Groove 44 is adapted for receiving a sealant, 
such as a plastisol and foaming agent, as disclosed in co-owned and 
copending U.S. pat. application Ser. No. 914,650, the disclosure of which 
is hereby incorporated by reference, to provide a relatively secure seal 
between second side 38 and outer surface 16 of workpiece 14 in the region 
40. Use of this sealant can provide a more effective closing off of the 
aperture. It is of course understood that the present invention can be 
used without this sealant. 
With reference to FIG. 1, it can be seen that the first side 3 of plug body 
26 has a number of depressions 28, 30, 32, and 34 formed therein with 
their respective corresponding protuberances 46, 48, 50, and 52 extending 
from the second side 38 of plug body 26. These protrusions extend into the 
aperture 20 to align the plug 12 with respect to the aperture 20 and 
workpiece 14, as well as cooperate with the sidewall 22 to snugly retain 
the plug 12 in the aperture 20, as described in more detail below. 
In FIG. 1A, depressions 28 and 32 form corresponding protrusions 46 and 50, 
as shown in FIG. 1C, for engaging the sidewall 22 of aperture 20 and 
therefore substantially restricting the movement of plug 12 along the axis 
B--B of FIG. 1A. Protrusions 46 and 50 need not completely abut the 
sidewall 22 so long as appropriately small tolerances, preferably in the 
range of 0.01-0.2 inch, are maintained. 
Also, in FIG. 1A, depressions 30 and 34 form protuberances 48 and 52, as 
shown in FIG. 1B, for engaging the sidewall 22 of aperture 20 and 
substantially restricting the movement of plug 12 along the axis A--A of 
FIG. 1A. Furthermore, as seen in FIG. 1B, protuberance 52 extends in a 
radially outward direction from protuberance 48 at an acute angle to 
planar side 38 to grippingly or lockingly engage the workpiece 14 in the 
region of juncture 24 where the sidewall 22 meets the inner surface 18. 
This protuberance, or finger, 52 is diametrically opposed to protuberance 
48 along axis A--A, and the distance between the two is chosen with 
respect to the size of the aperture 20 so that a snug fit is obtained 
against the sidewall 22. In this manner, plug 12 is restrained from 
falling out or being removed from aperture 20. 
Plug 12 can be installed into the wormpiece 14 in several ways. In one 
preferred way, protuberance 52 is initially straight, or substantially 
perpendicular to the second side 38 and the plane of the body 26. After 
the plug 12 is dropped or inserted into the aperture 20, a shaped bending 
tool 100 shown in FIG. 5 is inserted into the depression 34 and torque is 
applied to bend the protuberance 52 in a radially outward direction to 
engage the workpiece 14 adjacent the sidewall 20 in a locking or gripping 
fashion. For this embodiment, the finger 52 is preferably made of a 
material sufficiently pliable to permit such bending, but having 
sufficient spring-like qualities so as to exert a locking force against 
the workpiece once the bending torque is removed. 
In another preferred manner of inserting plug 12, finger 52 is already 
formed at an angle, preferably an angle A of between about 45 to about 89 
degrees, and most preferably at an angle of about 70 degrees, and is 
angled away from its diametrically opposed protrusion 48. The distance 
between finger 52 and protuberance 48 is chosen so that protuberance 48 
and its corresponding end of body 26 resist dropping into place in 
aperture 20 until a force, such as a blow by hammering, is applied in the 
vicinity of protuberance 48. For installation, finger 52 is first dropped 
into aperture 20. A force is then applied in the vicinity of protuberance 
48, thereby snapping or popping plug 12 into place. In this embodiment, 
the body 26 is preferably made of a material having a sufficient 
spring-like quality that can flex to the extent necessary to insert the 
plug and then spring back to exert the necessary retaining force against 
the workpiece and its sidewall. The bending tool of FIG. 5 can also be 
used with this embodiment to aid in bending finger 52 to pop or snap body 
26 in or out as desired. 
Another preferred embodiment of the present invention of the present 
invention is shown in FIG. 3, including FIGS. 3A, 3B, and 3C, which is 
substantially like the embodiment of FIG. 1 except that two angled fingers 
are used instead of one. In describing FIGS. 3A, 3B, and 3C, the same 
figure numbers are used except for primes for corresponding parts. The 
difference between the embodiment of FIG. 1 and that of FIG. 3 is that 
protuberance 48' is also a finger diametrically opposed to finger 52' 
along axis C--C. Protuberances 46' and 50' keep plug 12' aligned with 
respect to axis D--D, while fingers 48' and 52' keep plug 12' aligned 
along axis C--C as well as engage the workpiece in the vicinity of 
junction 20' to grippingly or lockingly engage the sidewall and keep the 
plug locked in place. The bending tool or key 100 of FIG. 5 can also be 
used to assist in installing plug 12' in its corresponding aperture. Also, 
if body 26' is made from a material having a sufficient spring constant, 
plug 12' can similarly be snapped into place by positioning fingers 48' 
and 52' at the entrance to the aperture and applying an inwardly directed 
force to snap or pop plug 12' into the aperture. 
It should be understood that various changes and modifications to the 
preferred embodiments described above will be apparent to those skilled in 
the art. Such changes and modifications can be made without departing from 
the spirit and scope of the present invention, and it is therefore 
intended that such changes and modifications be covered by the following 
claims.