Note: Descriptions are shown in the official language in which they were submitted.
CA 02277535 2003-09-04
63632-1493
Thread Forming Pipe Plug
Background
The present invention relates to self-tapping
fasteners, and more particularly to removable, self-tapping
threaded pipe plugs that will provide a sealed plug with
respect to fluids and liquids carried in the pipe, the
pressure tight plug being attained preferably without thread
sealing compounds.
National standards for pipe plug threads have been
developed and are widely used, these are well known in the
art and are referred to as National Pipe Thread standards -
Fuel and oil, viz., - NPTF standards. The standard tapered
NPTF pipe plug has been developed for use in engagement with
a pre-tapped pipe or workpiece. The pipe is prepared by
first drilling a straight hole, which is then taper reamed
to provide a tapered hole. Finally the tapered reamed hole
is tapped with a NPTF tapered tap to provide an internally
threaded, tapered aperture, the internal thread being formed
to a prescribed, predetermined configuration. With the
standard NPTF pipe plug, the roots of both the exterior and
interior threads are truncated slightly more than the crests
so that the roots have wider flats than the crests, which is
designed to produce metal-to-metal contact and deformation
occurring at the crests and roots coincident with threaded
engagement, prior to attaining thread flank contact. The
deformation of the crests of the internal and external
threads provides a sealing action at both the major and
minor diameters, in theory preventing spiral leakage through
the threads. In practice, however, due to the capillary
action of the fluid or gas
2
CA 02277535 1999-07-16
carried in the pipe, a potential spiral leakage path exists along the helix of
the
screw thread, if deformation does not completely seal the spiral path.
One disadvantage of the standard NPTF pipe plug is that during
installation of the NPTF plug into the pre-tapped hole cross-threading may
occur,
which results in an unsealed spiral path along the threads. The cross-threads
may
not be detected and thereby causes fluid leakage under pressure at the plug
seal
during service. When the cross-threading is detected, the joint often must be
scraped or reworked, both of which are costly and time consuming.
Sub
Accordingly, objects of the present invention include providing a pipe
plug which can cold-form threads into a pipe wall and which assures fluid
sealing
of the pipe without use of thread sealing compounds, as well as allowing
replacement in the pipe with a subsequently employed standard NPTF pipe plug,
if necessary. Also, the present invention allows a sealed pipe plug to be
formed
with a less costly fabrication and assembly procedure, as the tapping of the
pipe
aperture prior to engagement of the plug is eliminated. Also, because the pipe
plug of the present invention can engage an untapped internal wall and form
the
female NPTF threads as it is assembled, prevents cross-threading. Further, as
will be discussed more fully hereinafter, a sealing portion on the plug of the
present invention attains a positive seal, and augments that attained with the
inter-
CA 02277535 2003-12-22
63632-1493
engaged NPTF thread to assure a leak proof joint. Further,
it is anticipated that the novel plug of the present
invention can be used with an internally tapered opening in
a workpiece, as well as with a non-tapered opening.
In accordance with a first broad aspect, the
invention provides a plug and fastener for sealing in an
opening in a workpiece, said plug and fastener comprising: a
shank having an unthreaded sealing portion comprising a
plurality of non-helical annular sealing rings, a threaded
portion, and a head portion, said unthreaded sealing portion
being disposed between said head portion and said threaded
portion, said threaded portion engaging with an internal
wall of said opening and providing a first seal, said
unthreaded sealing portion entering said opening and being
configured to engage and provide a second seal against the
internal wall of said opening.
In accordance with a second broad aspect, the
invention provides a method of providing a seal between a
plug and fastener and a workpiece having an opening formed
therein, said method comprising the steps of: providing
said plug and fastener, said plug and fastener having a
shank, an unthreaded sealing portion comprising a plurality
of non-helical annular sealing rings, a threaded portion,
and a head portion, said unthreaded sealing portion entering
said opening and being disposed between said head portion
and said threaded portion, said threaded portion engaging
with an internal wall of said opening and providing a first
seal, and said unthreaded sealing portion being configured
to engage and provide a second seal against the internal
wall of said opening; providing said workpiece having said
opening; engaging said plug and fastener in said opening and
driving said plug and fastener into said opening such that
4
CA 02277535 2003-09-04
63632-1493
the threaded portion and unthreaded sealing portion enter
said opening and engage said internal wall to provide a
first seal and a second seal, respectively.
4a
CA 02277535 1999-07-16
Brief Description of the Drawiqgs
FIG. 1 is a side view in section of a self tapping pipe plug with sealing end
portion thereof shown initially entering a tapered pipe or workpiece aperture;
FIG. 2 is a side view, again in section, similar to FIG. 1 showing
completed engagement of the self tapping plug and the seal attained by the
sealing portion of the plug, as well as completion of cold-formed threading by
the
thread-forming portion of the plug fully inserted into the workpiece aperture;
FIG. 3 is an enlarged, fragmentary view of the sealing formation of the
plug sealing portion engaging the wall of the pipe hole shown in FIG. 2, and
illustrating the anticipated radial pre-stress distribution;
FIGS. 4-10 are side views of six further thread-forming pipe plugs with
six different configurations of the respective sealing tip portions thereof;
FIGS. 4a-l0a are enlarged fragmentary views of the sealing formations
produced in pipe apertures by the respective corresponding plugs shown in
FIGS.
4-10, also showing the anticipated pre-stressing patterns;
FIGS. 11, 13, 15, 17, 19, 21 and 23 are side, cross-sectional views of
several different plug and fasteners which are in accordance with different
embodiments of the present invention, showing each plug and fastener initially
entering an opening in a workpiece; and
5
CA 02277535 1999-07-16
FIGS. 12, 14, 16, 18, 20, 22 and 24 are side, cross-sectional views
showing the plug and fastener of FIGS. 11, 13, 15, 17, 19, 21 and 23,
respectively, fully engaged in the opening in the workpiece.
6
CA 02277535 2003-09-04
63632-1493
Detailed Description of the Illustrated Embodiments
Referring particularly to that which is
illustrated in FIGS. 1-3, a pipe plug constructed in
accordance with an embodiment of the present invention is
generally indicated by reference character 10. The plug 10
has a tapered shank 12 which includes a tapered, thread-
forming portion 14 from which a (progressively) tapered and
unthreaded sealing end portion 16 extends. Between the
thread-forming portion 14 and the driving head 11, there is
provided a standard NPTF tapered threads 15. The thread-
forming portion 14 may be of any known type of thread-
forming configuration, such as a tri-lobular design. One
such thread-forming design is well known in the trade under
the trademark TAPTITE~. Any type of thread-forming
configuration for the thread-forming portion 14 will be
acceptable, and the tri-lobular TAPTITE~ configuration is
disclosed herein only by way of example, and not as a
necessary element of the invention. In the embodiment
illustrated in FIGS. 1-3, the thread-forming portion 14 and
threads 15 conform to 1/8-27 standard NPTF pipe plug tap
dimensions with a taper, for example of 1.7899°. The thread-
forming portion 14 will cold-form internal threads to the
NPTF mating standard in a smooth-reamed, tapered wall 18 of
a pipe or workpiece P bore or hole 20. As shown in FIG. 1,
the sealing end portion 16 of the plug 10 is initially
insertable without engagement against the unthreaded opening
mouth 19.
Since the NPTF standards are well known to those
skilled in the art, the thread-forming portion 14 and the
threads 15 and 30 have not been shown to scale. It is to be
understood that the thread-forming portion 14 and full
threads 15 are formed to a standard. The thread-forming
7
CA 02277535 2003-09-04
63632-1493
portion 14 is designed to form an internal thread 30 in the
tapered wall 18 of the pipe bore 20. The internal thread 30
thus formed is configured in accordance with the NPTF
standard to be engaged by the threads 15, also formed to
said selected NPTF standard. When the selected NPTF threads
and 30 are engaged, there will be produced metal-to-
metal, interfering engagement between the respective crests
and roots of threads 15 and 30 in accordance with said
standard. This engagement results in a metal-to-metal seal
10 along the spiral thread path. As such, it is to be
understood that the thread-forming portion 14 and the
threads 15 and 30, as well as those thread configurations on
the embodiment of FIGS. 4-10, are configured to NPTF
standards, and are thus shown schematically.
15 As can be seen in FIG. 1, the sealing end portion
16 is spaced from the thread-forming portion 14 by a reduced
diameter medial portion 17. In the embodiment of FIG. 1,
the sealing end portion 16 includes three adjacently spaced
sealing rings 22, 24, and 26 which have progressively
reduced diameter to form a tapered relationship therebetween
as best illustrated in the enlarged view of FIG. 3 (more
fully described hereinafter).
Since the sealing rings 22, 24, 26 have
sufficiently smaller diameter than the initial, decreasing
bore diameter along the unthreaded opening mouth 19, there
is no initial engagement therebetween as the thread-forming
portion 14 begins to cold-form or swage the female thread
turns 30 (FIG. 2) into the smoothly reamed tapered wall 18
and unthreaded opening mouth 19, so that the sealing rings
22, 24, 26 do not initially engage the tapered wall and add
drive load to the preliminary female thread-forming
operation. However, as the thread-forming operation
proceeds to the point where the drive head 11 approaches
8
CA 02277535 2003-09-04
63632-1493
seating against the periphery of the pipe or workpiece
opening mouth 19a, the sealing tip rings 22, 24 and 26
progressively are driven into interference engagement
against the tapered wall 18 of the pipe. Each ring
progressively swages a respective annular sealing
deformation 23, 25 and 27 radially inwardly from the wall 18
against the angled lead face 22a, 24a and 26a of the
respective sealing rings 22, 24 and 26 as shown in FIG. 3.
The resulting annularly formed pipe wall deformation rings
23, 25 and 27 provide three additional pressure seal
formations which will completely seal the tapered wall 18.
Further, these deformations 23, 25 and 27 and the seals
attained therewith, extend about the full inner
circumference of the tapered wall 18, that is about a full
360°. The seal provided by the end portion 16 should provide
a complete sealing of the bore 20. The engagement of the
end portion 16 with the tapered wall 18 serves to pre-stress
the workpiece or pipe wall with the pre-stressing patterns
being illustrated schematically at X1, X2 and X3 in FIG. 3.
Further, the engagement of the NPTF threads 15 with the
female NPTF threads 30 formed by the thread-forming portion
14, will provide a standard NPTF type seal along the spiral
leak path provided by the engaged threads. This seal along
with that provided by the sealing end portion 16 assures
that the plug will not leak.
Further, keeping in mind the above discussion
regarding the method of fabrication with regard to the prior
art NPTF design, the above disclosed invention is possessed
of numerous advantages. First the tapping step for the
internally tapered bore is eliminated, as the self-tapping
thread-forming portion 14 on the plug will form the tapered
internal thread 30 in the workpiece. Secondly, as the
female or internal NPTF thread 30 is formed as the plug is
9
CA 02277535 2003-09-04
63632-1493
engaged with the workpiece, there is no danger of
cross-threading. Accordingly, the reworking and waste
associated with the prior art method of fabrication is
eliminated. Also, it should be noted that the engagement of
the sealing end portion 16 with the wall 18 of the
unthreaded opening mouth 19 serves to pre-stress the
workpiece, as illustrated at X1-X3 to permit said pipe or
workpiece P to better withstand internal pressures and also
prevent leakage.
Referring again to FIG. 2, since the female thread
turns 30 have a cold-formed or swaged minor diameter which
is smaller than the diameter of the original smooth wall
from which the mating threads were created, the smallest
formed female mating diameter 31 formed is nevertheless
larger than the outer diameter of the largest seal ring 22.
The three seal rings 22, 24 and 26 can then be withdrawn
with clearance past the smallest minor diameter 31 of the
formed female threads 30 which will, therefore, not be
disturbed or deformed when the plug 10 is entirely
unthreaded and removed from the pipe or workpiece.
Accordingly, the female threads 30 remain intact so that the
plug 10 or any replacement NPTF pipe plug having standard
NPTF threads can be threaded into the female threads 30 for
re-sealing the pipe. That is to say, engagement of a
standard NPTF plug will attain thread deformation and the
expected NPTF type seal, which is not as efficient as the
dual seal attained with the present invention.
Referring again to FIG. 3, in the illustrated
embodiment of the plug 10, the end portion sealing rings 22,
24 and 26 are disposed in a tapered relationship matching
the taper of the originally smooth tapered wall 18, for
example, approximately 1.7899° relative to the pipe axis (not
CA 02277535 2003-09-04
63632-1493
shown). The respective rings 22, 24 and 26 are separated by
lesser diameter land portions that cooperate with the rings
to define a series of spaced grooves. In order to roll form
these annular sealing rings 22, 24, 26 simultaneously in a
single operation with the formation of thread forming
portion 14 and threads 15, the volume of the material in the
rings should preferably be equal to each other. In order to
achieve such equal ring volume, and produce the tapered
relationship of the rings with relatively converging outer
diameters, the longitudinal widths of the rings increase
inversely relative to the converging decrease in outer
diameters so that the sealing ring 26 has the smallest outer
diameter with the largest longitudinally flat width 26b.
The leading faces 22a, 24a and 26a of the respective rings,
preferably form an angle of approximately 45° relative to the
respective face width 22b, 24b and 26b in order to help
minimize the resistance between these front faces as the
seal rings 22, 24, 26 embed and swage the tapered wall 18 to
form the annular internal wall deformation rings 23, 25 and
27. The respective annular trailing faces 22c, 24c and 26c
can form angles of approximately 30° relative to the
respective ring widths 22b, 24b and 26b as shown in FIG. 3.
As such, referring to the pre-stress patterns X1-X3, the
forward most area of pre-stressing X1 is the widest with the
area X3 the narrowest. The degree of pre-stressing is
greater in area X3 than at area X1 due to the fact that the
extent of radial interference is greater at area X3 than area
X1 and the force is concentrated over a smaller area at X3.
Referring now to FIGS. 4 and 4a, a second
embodiment of a pipe plug construction in accordance with
the present invention is generally indicated by reference
character 10. In this embodiment of the pipe plug, the
unthreaded sealing end portion 116 is a smooth cylindrical
11
CA 02277535 2003-09-04
63632-1493
shank portion of reduced diameter extending without taper
from the tapered, thread-forming portion 114. The threads
115, similar to the threads 15 of the embodiment of
FIGS 1-3, is a standard NPTF thread. The operation of
thread-forming portion 114 and threads 115 correspond to
those of thread-forming portion 14 and threads 15 of the
FIGS 1-3 embodiment and as such these functions are not
discussed in detail. The end of the sealing end portion 116
has a rounded rim 122 in order to minimize initial
interference with the tapered wall 118 (FIG. 4a) as the
thread-forming portion 114 begins cold-forming the female
thread turns 130 (FIG. 4a) into the tapered wall 118. As
shown in FIG. 4a, the annular lead side wall portion 117 of
the cylindrical sealing end portion 116 will be interference
engagement with tapered wall 118 and will cold-form or swage
an annular, 360°; sealing deformation 123 radially inwardly
from the tapered wall 118 to produce a leading pressure seal
formation as the thread-forming portion 114 completes cold-
forming the female thread turns 130 and the NPTF threads 115
engage the internal NPTF threads 130 formed by thread-
forming portion 114. The sealing deformation 123 provides
assured sealing of the sealing end 116 against the tapered
pipe wall 118 to prevent leakage upstream of the spiral leak
path through the thread turns 130 formed in the pipe bore
wall 118. The pre-stressing pattern of the tapered wall 118
attained with this embodiment is illustrated at X4, FIG. 4a.
Referring now to FIGS. 5 and 5a, a third
embodiment 210 of the pipe plug in accordance with the
present invention is shown in which the sealing end portion
216 includes four spaced sealing rings 222, 224, 226 and
228. The sealing rings form a tapered relationship so that
the sealing ring 228 has the smallest peripheral diameter
228a and the ring 222 has the largest peripheral diameter
12
CA 02277535 2003-09-04
63632-1493
222a. The sealing rings 222, 224, 226 and 228 perform
swaging deformation of the pipe bore wall 218 to form
annular, 360° pipe wall deformation rings 223, 225, 227 and
229 which add additional pressure seal augmenting the seal
formation of the formed female pipe wall threads 230 against
the thread-forming portion 214 of the plug, without however
the fabrication complexity of the angled leading and
trailing faces provided on the sealing rings 22, 24 and 26
of the first pipe plug embodiment 10 shown in FIGS. 1-3.
The prestressing pattern attained with the end portion 216
is shown at X5.
The embodiments of FIGS. 5 and 5a, as well as
those of FIGS. 6-9 and 6a-9a, are similar to those of
FIGS. 1-3 and 4 and 4a with respect to the general fastener
design in that all include a driving end portion in the form
of a driving head and a threaded shank. The threaded shank
is divided in two portions 214 and 215 (FIGS. 6 and 6a).
Similar to thread-forming portion 14 and threads 15 of FIGS.
1-3, the thread-forming portion 214; 314 etc. are of the
general type and kind disclosed with respect to portion 14,
FIGS. 1-3, that is of a tri-lobular configuration. Here
again, the type of thread-forming configuration used with
respect to these embodiments is not critical to the
invention. As an alternate to the tri-roundular or
tri-lobular configuration discussed for any of the disclosed
embodiments, the thread-forming portions 14; 114; 214 etc.
could be of five (5) lobe design, or any other thread-
forming configuration, many others of which are well known
in the art. All that is required is that the thread-forming
portions 14; 114; 214 etc., be capable of forming a standard
NPTF internal thread 30; 130; 230 in tapered wall 18; 118
etc. Correspondingly, the threads 15; 115; 215, etc., are
of standard NPTF configuration designed to mate with the
13
CA 02277535 2003-09-04
63632-1493
internal NPTF threads formed by the thread-forming portions
14; 114; 214, etc. Accordingly, with regard to the
discussion that follows regarding the remaining embodiments
of FIGS. 6-9, while the respective thread portions 314, 414,
etc.; 315; 415, etc. and 330; 430 are designated, they will
not be discussed in detail and it is to be understood that
these threaded portions correspond and function as do
thread-forming portions 14 and threads 15 and 30, FIGS. 1-3.
Only the novel configuration of the respective sealing end
portions 316; 416, etc. will be discussed in detail.
With the above in mind, reference is now directed
to FIGS. 6 and 6a, wherein a fourth embodiment of a pipe
plug, designated 310, in accordance with the present
invention includes a sealing end portion 316 having a single
sealing ring 322. The sealing ring 322 has a generally
narrow uniform cylindrical peripheral surface 324 as best
shown in FIG. 6a. The peripheral surface 324 has a
conically tapered leading face 326 against which the ring
322 swages an annular, 360°, a sealing deformation ring 328
radially inwardly from the tapered wall 318. The
longitudinal taper of the conical lead face 326 promotes an
extended surface for engagement of the extended bore wall
deformation 328 for assured seal by the sealing end portion
316 and prevention of any spiral leak through the
cold-formed female pipe thread turns 330 by the plug
thread-forming portion 314. The pre-stress pattern is
illustrated at X6, FIG. 6a. As can be seen, the pre-
stressing is greatest proximate the land or cylindrical
surface 324, and tapers off toward the end of the sealing
end portion 316. Here again, the seal provided by the
14
CA 02277535 2003-09-04
63632-1493
interfering engagement of sealing portion 316 with tapered
wall 318 and the deformation thereof at 328 provides a
pressure seal that enhances the overall sealing action
CA 02277535 1999-07-16
and works in tandem with the seal provided by the engagement of standard NPTF
threads 315 and 330.
Referring now to FIGS. 7 and 7a, a fifth embodiment 410 of a pipe plug in
accordance with the present invention has a sealing end portion 416 which has
a
generally bulbous or otherwise curved peripheral surface 422 formed in
truncate
extension from a reduced shank portion 417 at one end and a truncate end
surface
424 at the terminal end of the plug. The peripheral surface 422 may be
generally
spherical, or elliptical, or merely generated from any curved surface. The
arcuate
sealing surface 422 cold-forms the wall 418 to produce a swaged or sheared
annular, 360 °, sealing deformation 428. The maximum diameter 426 of
the
arcuate sealing tip surface 422 is smaller than the minor diameter of the
smallest
female thread turn cold-formed by the thread-forming plug portion 414 to
enable
withdraw clearance of the sealing tip portion 416 through the formed female
thread turns 430 to enable plug removal without disturbance of the formed
female
pipe threading turns. The pre-stressing pattern of wall 418 is illustrated at
X~.
In FIGS. 8 and 8a, a sixth embodiment 510 of a pipe plug in accordance
with the present invention is illustrated as having a sealing end portion 516
including three cylindrically formed sealing rings 522,524 and 526. The
sealing
rings 522,524 and 526 are serially contiguous or stepped with progressively
reduced respective diameters to form an incrementally tapered relationship
therebetween converging toward the planar terminal end 527 of the fastener.
16
CA 02277535 1999-07-16
This end 527 has a rounded end rim 529 against which a swaged annular wall
deformation from the tapered pipe bore wall 518 provides the pressure seal at
the
plug sealing tip portion 516. The sealing rings 522, 524, 526 produce
progressively increasing interference and deformation of the bore wall 518.
Thus, the pre-stressed pattern as illustrated at X8 is attained. The seal
achieved
with the end portions 516 work with the standard NPTF seal achieved with the
engagement of threads 515 and 530 to assure that the plug does not leak.
In FIGS. 9 and 9a a seventh embodiment is shown. This seventh
embodiment 610 of a pipe plug in accordance with the present invention has a
sealing tip portion 616 in which an annular, arcuate side wall surface is
portioned
into six annular rings 622,624,626,628,630 and 632 which are narrowly spaced
by respective annular recesses or grooves 623,625,627,629 and 631. The spacing
grooves provide generally sharp lead edges on the respective sealing rings
which
bite into the tapered bore wall 618 to form a series of annular sealing
deformations 640,642,644,646 and 650 and a plurality of additional pressure
seal
formations which completely eliminate any potential spiral leak path between
female thread turns 630 formed into the pipe bore and the thread-forming
portion
614 of the pipe plug 610. The pre-stressing pattern achieved with end portion
616 is shown at X9.
Referring now to FIGS. 10 and 10a, an eighth embodiment 710 for a pipe
plug in accordance with the present invention has a sealing end portion 716
17
CA 02277535 2003-09-04
63632-1493
having a single, elongate sealing ring 722. The sealing
ring 722 has a generally elongate, conically tapered
peripheral surface 724 and a generally sharp-edged, annular
leading rim 726 which bites into the tapered wall 718 to
shear or swage an annular sealing ring deformation 728
radially inwardly from the tapered wall 718. The sealing
deformation 728 forms an additional pressure seal against
the rim 726 and the elongate conical wall 724 provides
extended seal surface against tapered wall 718 which combine
to completely eliminate any potential spiral leak path
between the female thread turns 730 formed into the tapered
wall 718 in the thread-forming portion 714 of the plug 710.
A backwardly sheared, annular sealing deformation 723 is
also formed at the rear, sharpened-edge annular rim 725 of
the conical sealing tip wall 724. Radial clearance for the
rear seal deformation 723 is provided by the reduced
diameter medial shank portion 717 of the plug 710. Here
again the pre-stress pattern has been illustrated
schematically, and is indicated at Xlo.
While the sealing end portion 16; 116...716, have
been illustrated in conjunction with a self-threading or
tapping plug 10, several alternatives should be kept in
mind. First, the plug or plugs 10, 110...710 may be employed
without the sealing end portion 16; 116...716. Further, the
sealing end portion 16; 116...716 are not limited to use on
the self-threading plug 10; 110...710 of the present
invention, but may be used on standard NPTF plugs that are
not self-tapping and are engaged in pre-tapped pipe on
workpiece apertures.
18
CA 02277535 1999-07-16
FIGS. 11-24 illustrate several combination plug and fasteners 810, 910,
1010 and 1110 which are in accordance with still further embodiments of the
present invention. As shown, each respectively includes a sealing portion 816,
916, 1016 and 1116 located between a head portion 81 l, 911, 1011 and 1111 and
a threaded portion 814, 914, 1014 and 1114, with the head portion 811, 911,
1011
and 1111 being at one end of the plug and fastener 810, 910, 1 O 10 and 1110,
and
the threaded portion 814, 914, 1014 and 1114 being at the other, opposite end
of
the plug and fastener 810, 910, 1010 and 1110. Each plug and fastener 810,
910,
1010 and 1110 is configured such that the respective threaded portion 814,
914,
1014 and 1114 is meant to initially enter an opening 19 in a workpiece P, and
the
sealing portion 816, 916, 1016 and 1116 follows the threaded portion 814, 914,
1014 and 1114 into the opening 19. When each plug and fastener 810, 910, 1010
and 1110 is fully engaged in the opening (shown in FIGS. 12, 14, 16, 18, 20,
22
and 24), the respective threaded portion 814, 914, 1014 and 1114 engages an
1 S internal wall of the opening 19 to form a first seal, and the sealing
portion 816,
916, 1016 and 1116 engages an internal wall of the opening to form a second
seal.
Each of the combination plug and fasteners 810, 910, 1010 and 1110 will
now be described individually, pointing out differences between them. The plug
and fastener 810 illustrated in FIGS. 11-16 includes a tapered threaded
portion
814 as well as a tapered sealing portion 816. The sealing portion 816 includes
a
19
CA 02277535 1999-07-16
pair of sealing rings 822, 824, where the respective diameters 823, 825 of the
rings 822, 824 differ from each other and taper or converge toward the
threaded
portion 814. In other words, the diameter 825 of sealing ring 824 which is
closer
to the threaded portion is smaller diameter than the diameter 823 of sealing
ring
822 which is closer to the head portion 811. Additionally, a longitudinal
width
824b of the sealing ring 824 which is closer to the threaded portion 814 is
larger
than a longitudinal width 822b of the sealing ring 822 which is closer to the
head
portion 811. In other words, the sealing rings 822 and 824 have peripheral
surfaces which have differential longitudinal widths 822b and 824b,
respectively,
which are inversely proportional to their respective outer diameters 823 and
825.
Preferably, the leading faces 822a and 824a of the respective rings 822 and
824,
form an angle of approximately 45 ° relative to the respective widths
822b and
824b in order to help minimize resistance as the seal rings 822, 824 embed and
swage an internal surface of the opening 19, as will be described (for
clarity,
reference numerals 822, 824, 822a, 824a, 822b and 824b are indicated only in
FIG. 11 ).
As shown in FIGS. 11 and 12, the plug and fastener 810 may be engaged
in an opening 19 in a workpiece P where the opening is formed of a tapered
bore
850 and tapered counter bore 852. The bore 850 and counter bore 852 are
tapered in that, as indicated in FIG. 11, diameter A of bore 850 is less than
CA 02277535 1999-07-16
corresponding diameter C, and diameter B of counter bore 852 is less than
corresponding diameter D.
Alternatively, as shown in FIGS. 13 and 14, the plug and fastener 810 may
be engaged with an opening 19 in a workpiece P where the opening is formed of
a tapered bore 850 and non-tapered counter bore 852a. As shown in FIG. 13,
diameters B and D of the counter bore 852a are substantially equivalent while
diameter A of bore 850 is less than diameter C. Still further, as shown in
FIGS.
and 16, the plug and fastener 810 may be engaged in an opening in a
workpiece P where the opening is formed of a non-tapered bore 850a and a non-
10 tapered counter bore 852a. In this case, as shown in FIG. 15, diameters A
and C
of the bore 850a are substantially equivalent, and so are diameters B and D of
the
counter bore 852a.
Regardless of the shape of the opening 19 and the dimensions of the bore
850, 850a and counter bore 852, 852a, when the combination plug and fastener
15 810 is initially inserted into the opening 19, as shown in FIGS. 11, 13 and
15, the
threaded portion 814 is initially inserted therein. Because the counter bore
852,
852a has a larger diameter (diameters B and D in each of FIGS. 1 l, 13 and 15)
than does the threaded portion 814 of the plug and fastener 810, the threaded
portion 814 does not engage an internal wall 854, 854a of the counter bore
852,
852a and instead proceeds to engage an internal wall 856, 856a of the bore
850,
850a as the plug and fastener 810 is engaged in the opening. Because the
21
CA 02277535 1999-07-16
threaded portion 814 of the plug and fastener 810 does not engage the internal
wall 854, 854a of the counter bore 852, 852a, no potential spiral leak path is
formed thereon by the threaded portion 814.
As shown, preferably the internal wall 856, 856a of the bore 850, 850a is
S provided as being initially unthreaded. Hence, the threaded portion 814 of
the
plug and fastener 810 forms threads on the internal wall 856, 856a of the bore
850, 850a as the threaded portion 814 engages therewith. Alternatively, it is
possible to provide that the internal wall 856, 856a of the bore 850, 850a is
pre-
threaded.
As shown in FIGS. 12, 14 and 16, as the plug and fastener 810 further
advances in the opening 19, the sealing portion 816 engages the internal wall
854,
854a of the counter bore 852, 852a much like the engagement of the sealing
portions of the plugs previously described. When the plug and fastener 810 is
fully engaged in the opening 19, the engagement between the threaded portion
814 of the plug and fastener 810 and the internal wall 856, 856a of the bore
850,
850a provides a first seal, and the engagement between the sealing portion 816
of
the plug and fastener 810 and the internal wall 854, 854a of the counter bore
852,
852a provides a second seal. Because the sealing rings 822 and 824 (as
mentioned, for clarity, reference numerals 822 and 824 are shown only in FIG.
11 ) do not comprise one continuous helical sealing structure, the sealing
portion
22
CA 02277535 1999-07-16
816 of the plug and fastener 810 does not provide a helical leak path along
the
internal wall 854, 854a of the counter bore 852, 852a.
The combination plug and fasteners 910 and 1010 illustrated in FIGS. 17-
20 differ from plug and fastener 810 only in that plug and fasteners 910 and
1010
include threaded portions 914, 1014 which are not tapered. The sealing
portions
916 and 1016 of the plug and fasteners 910 and 1010, respectively, are
identical
to the sealing portion 816 of plug and fastener 810, and provide a pair of
sealing
rings having the same structure of the sealing rings 822 and 824 of sealing
portion 816. Additionally, like the plug and fastener 810, each plug and
fastener
910 and 1010 includes a head portion 911 and 1011, respectively, where the
sealing portion 916 and 1016 is located between the head portion 910 and 1010
and the threaded portion 914 and 1014.
As shown in FIGS. 17 and 18, plug and fastener 910 can be engaged with
an opening 19 in a workpiece P where the opening is formed of a non-tapered
bore 850a and non-tapered counter bore 852a. In this case, as shown in FIG.
17,
diameters A and C of bore 850a are substantially equivalent, and so are
diameters
B and D of counter bore 852a. The engagement of the plug and fastener 910 with
the internal walls 854a and 856a thereof is identical to that which was
described
in relation to plug and fastener 810. The plug and fastener 910 forms a first
and
second seal with the internal walls 854a and 856a employing the threaded
portion
914 and sealing portion 916. This is shown in FIG. 18.
23
CA 02277535 1999-07-16
As shown in FIGS. 19 and 20, plug and fastener 1010 can be engaged in
an opening 19 essentially provided by two workpieces P, and PZ where the first
workpiece P, provides a bore 850b and the second workpiece PZ provides a
counter bore 852b. Hence, as shown in FIG. 20, engagement of the plug and
fastener 1010 in the opening 19 provides that the two workpieces P, and P2 are
secured together due to the engagement of the threaded portion 1014 with
workpiece P, and the engagement of the sealing portion 1016 with workpiece P2.
Of course, the other embodiments previously described may also be so engaged
with two workpieces in much the same manner to provide for securement thereof.
As shown, the bore 850b provided in workpiece P~ may be pre-threaded.
The plug and fastener 1110 illustrated in FIGS. 21-24 differs from plug
and fastener 810 only in that the sealing portion 1116 of plug and fastener
1110 is
comprised of a pair of sealing rings 1122 and 1124 where the longitudinal
widths
1122a and 1122b thereof are substantially equal. However, it is preferred
that,
like plug and fastener 810, the diameters 1123, 1125 of the rings 1122, 1124
differ from each other and taper toward the threaded portion 1114. In other
words, the sealing ring 1124 which is closer to the threaded portion 1114
preferably has a smaller diameter 1125 than does the diameter 1123 of sealing
ring 1122 which is closer to the head portion 1111. Likewise, preferably
leading
faces 1122a and 1124a of the respective rings 1122 and 1124, form an angle of
approximately 45 ° relative to the respective widths 1122b and 1124b in
order to
24
CA 02277535 1999-07-16
help minimize the resistance between these front faces as the seal rings 1122,
1124 embed and swage an internal surface of the opening 19 as will be
described
(for clarity, reference numerals 1122, 1124, 1122a, 1124a, 1122b, 1124b, 1123
and 1125 are indicated only in FIG. 11 ).
As shown in FIGS. 21 and 22, plug and fastener 1110 can be engaged with
an opening 19 in a workpiece P where the opening is formed of a tapered bore
850 and a non-tapered counter bore 852a. In this case, as shown in FIG. 21,
diameter A of bore 850 is less than diameter C, while diameters B and D of
counter bore 852a are substantially equivalent. Alternatively, as shown in
FIGS.
23 and 24, plug and fastener 1110 can be engaged with an opening 19 in a
workpiece P where the opening is formed of a tapered bore 850 and a tapered
counter bore 852. In this case, as shown in FIG. 23, diameters A and B are
less
than corresponding diameters C and D, respectively. Regardless, engagement of
the plug and fastener 1110 therein is identical to that which was described in
relation to plug and fastener 810. The plug and fastener 1110 preferably forms
a
first and second seal with the internal walls of the bore 850 and counter bore
852
employing the threaded portion 1114 and sealing portion 1116 thereof, as
illustrated in FIGS. 22 and 24.
25
CA 02277535 2003-09-04
63632-1493
While preferred embodiments of the present
invention are shown and described, it is envisioned that
those skilled in the art may devise various modifications
and equivalents without departing from the spirit and scope
of the appended claims.
For example, the configuration of the sealing end
portion 16; 116; 216 etc. may take varying shape. The
primary considerations are that the sealing end portion
achieve interfering engagement with the bore wall to such an
extent as to attain a seal. While deformation and cold-
forming of the bore wall is preferred, it is not absolutely
necessary to achieve a complete seal, however, deformation
tends to produce interference which results in a seal.
Further, while the thread-forming portions 14; 114; 214
etc., are disclosed to be formed as tri-lobular or tri
roundular in accordance with the well known TAPTITE~ type of
thread-forming design, other thread-forming configurations
for thread-forming portions 14; 114 etc., may be employed,
these are also well-known in the art. The only requirement
is that the thread-forming portions 14; 114 etc., produce
the desired internal thread in accordance with the NPTF
standards. Further, as discussed above, the plug 10;
110...710 may be used without a forward sealing portion 16;
116...716, or the forward sealing portion designs may be used
on standard NPTF plugs.
26
