U.S. patent application number 09/800793 was filed with the patent office on 2002-09-12 for sealing surface for plastic closure with radial seal.
Invention is credited to Hathaway, John, Taylor, Dale.
Application Number | 20020125205 09/800793 |
Document ID | / |
Family ID | 25179372 |
Filed Date | 2002-09-12 |
United States Patent
Application |
20020125205 |
Kind Code |
A1 |
Hathaway, John ; et
al. |
September 12, 2002 |
Sealing surface for plastic closure with radial seal
Abstract
A novel method for sealing a plastic closure to a container
flange using an elastomeric gasket. A plurality of annular sealing
bands are positioned on the diametric sealing surface of the
closure on which the gasket rests. As the closure is threaded into
the container, the annular sealing bands become embedded within the
gasket to improve the seal and overcome the negative sealing
effects of the parting line flash present on the closure portion of
the seal gland as a result of the manufacturing process.
Inventors: |
Hathaway, John; (Fort Wayne,
IN) ; Taylor, Dale; (Hamilton, IN) |
Correspondence
Address: |
Kwadjo Adusei-Poku
Masco Tech, Inc.
21001 Van Born Rd.
Taylor
MI
48180
US
|
Family ID: |
25179372 |
Appl. No.: |
09/800793 |
Filed: |
March 7, 2001 |
Current U.S.
Class: |
215/356 ;
215/352; 220/304 |
Current CPC
Class: |
B65D 39/082 20130101;
B65D 2251/205 20130101 |
Class at
Publication: |
215/356 ;
215/352; 220/304 |
International
Class: |
B65D 039/08; B65D
053/02 |
Claims
What is claimed is:
1. A closure adapted to be seated within an opening of a container
for selective access to materials within the container, said
closure comprising: a cap portion, an annular side wall portion
beneath the cap portion, the annular side wall portion comprising a
top neck section, a threaded section beneath the top neck section,
and a bottom section beneath the threaded section, and an annular
sealing band situated around the top neck section of the annular
side wall portion.
2. The closure as in claim 1, further comprising a plurality of
annular sealing bands situated around the top neck section of the
annular side wall portion.
3. A plastic closure for threaded engagement with a container, the
closure employing a gasket to provide a seal between the closure
and the container, the closure comprising: a cap portion, an
annular side wall portion beneath the cap portion and having a
smaller diameter than the cap portion, the annular side wall
portion comprising a top neck section, a threaded section beneath
the top neck section, and a bottom section beneath the threaded
section, and a plurality of annular sealing bands situated around
the top neck section of the annular side wall portion, whereby as
the closure is threaded within the container, the sealing bands
releasably engage the gasket, thereby improving the effectiveness
of the gasket.
4. The closure as in claim 3, wherein the annular sealing bands
have a sawtooth shape pointing upwards and outwards, for better
engagement with the gasket.
5. The closure as in claim 4, wherein the annular sealing bands
have a top surface and an angled surface, the angled surface being
angled upwards approximately 50.degree. from horizontal.
6. The closure as in claim 5, wherein the top surface of the
annular bands is displaced downwards approximately 10.degree.
degrees from horizontal.
7. The closure as in claim 3, wherein the annular sealing bands are
integrally molded within the closure.
8. The closure as in claim 7, wherein the bottom section of the
annular side wall portion is tapered for ready insertion with the
container.
Description
I. FIELD OF THE INVENTION
[0001] This invention relates to threaded closures for steel and
plastic drums, particularly drums using elastomeric gaskets
positioned around the closure for enhanced sealing. In particular,
the closure has a plurality of sealing rings positioned along its
sealing surface for proper positioning and improved contact with
the sealing gasket.
II. BACKGROUND OF THE INVENTION
[0002] One type of closure and flange sealing mechanism commonly
used in steel drum manufacturing involves using an elastomeric
gasket positioned radially on a closure. The closure is threaded
into a flange, creating a seal gland between them. As the closure
is initially threaded into the flange, the elastomeric seal easily
starts into the gland. As the closure is threaded further into the
flange, the gland becomes tighter causing the gasket to be
compressed radially like a cork, creating an effective seal.
[0003] Drum manufacturers perform critical testing on the
flange/closure seal to ensure that the seal is adequate. The
generally accepted manufacturing method of producing plastic
closures for use in this particular application requires the use of
a split-block mold, which offers the opportunity for "parting line
flash," otherwise referred to as parting line mismatch, to be
created on the closure's radial sealing surface. The sharp edged
surface created by the flash or mismatch is not an ideal sealing
surface, and provides a potential leak path through the gland. This
is especially applicable when hard elastomeric gaskets are used,
for example, low density polyethylene gaskets that may or may not
be irradiated, or cork gaskets. The polyethylene gaskets are
preferred when sealing aggressive solvents that soft gaskets are
typically not chemically compatible with.
[0004] In an effort to improve the closure performance, closure
manufacturers often perform a secondary operation on the closure
when parting line flash or mismatch is present on the sealing
surface. Secondary operations include machining the entire outer
circumference of the closure sealing gland, or else removing the
flash or mismatch through a secondary machining process. In either
case, the secondary operations add cost to the product, and lower
potential profits to the manufacturer.
[0005] This invention creates an improved sealing surface on the
closure which drastically improves the performance of a hard
elastomeric gasket when used in the above described gland,
eliminating the need for a secondary operation to remove parting
line flash on the closure sealing surface.
III. SUMMARY OF THE PRESENT INVENTION
[0006] The invention consists of a plurality of sealing rings
placed on the diameter of a closure used to seal steel or plastic
drums that utilize a diametric or cork style sealing gasket. The
lower rings (nearest the threads) bite into the gasket as the
closure is threaded into the flange, thereby improving the seal.
This is due to the radial compression that occurs to the seal as
the closure is threaded into the flange. The upper rings cause the
gasket to remain vertical so that it enters the gland in the proper
orientation. Without the upper ring, the gasket can cock to one
side or the other, and potentially be forced out of the gland as
the closure is threaded into the flange, rather than becoming
compressed within the gland. Also, the upper rings act as
additional sealing components, since they too are compressed into
the gasket as the closure is tightened into the flange.
[0007] The negative effect of typical levels of parting line flash
and mismatch, that often occur on the closure sealing surface
during generally accepted methods of manufacturing, is greatly
reduced when the multiple rings are used. Manufacturing becomes
more efficient with the use of this new sealing design since no
secondary operation is required to remove the parting line flash
and mismatch.
IV. BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present invention will be more fully understood by
reference to the following detailed description of a preferred
embodiment of the present invention when read in conjunction with
the accompanying drawings, in which like reference characters refer
to like parts throughout the views and in which:
[0009] FIG. 1 is an exploded perspective view of the closure
according to the present invention in combination with the sealing
gasket and the container;
[0010] FIG. 2 is a side elevational view of the closure embodying
the present invention;
[0011] FIG. 3 is cross-sectional view of a portion of the closure
showing the gasket in place over the sealing bands with the closure
being partially threaded into the container;
[0012] FIG. 4 is an cross-sectional view of a portion of the
closure showing the sealing bands of the instant invention embedded
within the gasket as the gasket is compressed between the closure
and the container; and
[0013] FIG. 5 is an enlarged side elevational view of the portion
"5" of the closure in FIG. 1, showing the sealing bands.
V. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT
INVENTION
[0014] The instant invention is directed towards a threaded closure
10 adapted to close and seal a container 50 such as a steel or
plastic drum. This closure 10 provides selective access to
materials within the container 50. Referring to FIG. 1, the closure
10 embodying the present invention is threadably received within
the container 50 opening to seal the container 50 and maintain
material within the container 50 during transport and storage. A
gasket 60 slips over the threads 38 of closure 10 and nests between
the closure 10 and the container 50 to ensure proper sealing.
[0015] Referring to FIG. 2, the closure 10 comprises a cap portion
20 over an annular side wall portion 30, the annular side wall
portion 30 being adapted to matingly fit within the opening of the
container 50. The annular side wall portion 30 comprises a top neck
section 32, a threaded section 34 and a bottom neck section 36
beneath the threaded section 34. The base of the bottom neck
section 36 may be rounded, tapered or otherwise adapted to be
readily inserted within a corresponding opening in the container
50. Above the bottom neck section 36, the threaded section 34
comprises external threads 38 adapted to cooperate with the
corresponding threads 52 of the container 50 opening, for secure
attachment of the closure 10 to the container 50. Above the
threaded section 34, the top neck section 32 includes a plurality
of annular sealing bands 40 and 42. In a preferred embodiment of
the invention, the annular sealing bands 40 and 42 appear as
upwardly and outwardly extending barbs (see FIG. 5). Extending
outward from the top of the top neck section 32 is the cap portion
20 of the closure 10. This overlapping cap portion 20 forms a
shoulder 22 that supports the closure 10 above the opening of the
container 50. The cap portion 20 also provides a gripping surface
for an operator to remove the closure 10 from the container 50.
[0016] Referring to FIG. 3, the closure 10 is shown partially
threaded into the container 50. The container 50 has an upwardly
extending annular flange 52 around the opening for receiving and
supporting the closure 10. As shown, the mating threads 54 of the
container 50 are situated on the inner surface of the upwardly
extending annular flange 52. To provide enhanced sealing between
the closure 10 and the container 50, it is conventional to use a
sealing gasket 60, situated under the shoulder 22 between the cap
portion 20 and the top neck section 32 of the closure 10. The
gasket 60 is placed on the closure 10 by moving the gasket 60 over
the threads 38. The gasket 60 is then anchored under the shoulder
22 beneath cap portion 20 and over the sealing bands 40 and 42. Now
referring to FIG. 4, as the closure 10 is threaded within the
container 50, the gasket 60 is radially compressed between the
closure 10 and the annular flange 52 of the container 50, thereby
providing an enhanced sealing mechanism.
[0017] Although the conventional method of using a gasket 60 to
provide enhanced sealing is widely used within the industry, it has
been observed that the sealing qualities of the gasket 60 are
greatly reduced by the presence of a parting line flash or a
parting line mismatch on the sealing surface of the top neck
portion of the closure 10. The parting line flash is a direct
result of the split-block mold used in the manufacture of the
closure 10. The parting line flash disrupts the sealing surface of
the closure 10 by causing a line of separation between the sealing
surface of the top neck section 32 and the gasket 60. This is most
often observed when a hard elastomeric gasket or a cork gasket is
used. To overcome this flash problem, the industry has typically
resorted to performing a secondary operation on the closure to
remove the flash from the sealing surface of the top neck section
32 of the closure 10. These secondary operations include machining
the entire sealing surface of the closure, or using some polishing
mechanism to remove the flash.
[0018] Pursuant to the instant invention, and as shown in FIGS. 2
through 5, the preferred embodiment employs a plurality of annular
sealing bands 40 and 42 around the sealing surface of the top neck
section 32 of the closure 10. The sealing bands 40 and 42 may have
many shapes, for example, the bands 40 and 42 may appear rounded or
shaped like triangular teeth. However, in the preferred embodiment
the sealing bands are shaped as upward and outwardly extending
saw-tooth barbs. As best shown in FIG. 5, the top surface 41 of the
sealing bands 40 and 42 is slightly displaced downwards from
horizontal. A 10.degree. downward angle may be used. By contrast,
the upwardly angled surface 43 is preferably displaced
approximately 50.degree. degrees from horizontal. This sawtooth
shape facilitates both passing the gasket 60 over the sealing bands
40 and 42 and proper seating of gasket 60 under the cap portion 20.
As the gasket 60 is placed over the closure 10, the shape of the
bands 40 and 42 allow the gasket 60 to slide upwards over the
upwardly angled surface 43 with the minimum of resistance. Further,
once the gasket 60 has passed over the sealing bands 40 and 42, the
reduced downward slope of top surface 41 resists the downward
movement of gasket 60, thereby holding the gasket 60 in its proper
position abutting the shoulder 22. Although it is preferably to
make the sealing bands 40 and 42 as pointed as possible in order to
facilitate penetration into the gasket 60, the actual tips may be
rounded due to limitation inherent in the molding process.
[0019] As the closure 10 is threaded into the annular flange 52 of
the container 50, the gasket 60 is radially compressed between the
closure 10 and the container 50. In particular, starting with the
lowermost sealing band, the sealing bands 40 and 42 become embedded
within the gasket 60. Furthermore, the upper sealing bands serve
additionally to maintain the gasket 60 in the proper vertical
orientation with respect to the sealing surface of the top neck
section 32, as the gasket 60 is compressed between the container 50
and the closure 10. In effect, the resulting sealing band-gasket 60
interface is sufficient to overcome the negative sealing effects of
the parting line flash, thereby creating an improved seal between
the closure 10 and the container 50, without the need for
additional and costly secondary operations on the closure 10 to
remove the parting line flash. Although the invention may be
practiced with a single sealing band 40 around the sealing surface
of the top neck section 32, the preferred embodiment employs two or
more sealing bands 40 and 42. The additional sealing bands provide
positional stability to the gasket as the closure is being threaded
into the container.
[0020] The foregoing detailed description has been given for
illustrative purposes only and is not intended to limit the scope
of the invention, as some modifications will be obvious to those
skilled in the art without departing from the scope and spirit of
the invention as recited in the appended claims.
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