U.S. patent application number 11/091146 was filed with the patent office on 2005-09-29 for pipe coupling having wedge shaped keys.
This patent application is currently assigned to Victaulic Company of America. Invention is credited to Dole, Douglas R..
Application Number | 20050212284 11/091146 |
Document ID | / |
Family ID | 35064271 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050212284 |
Kind Code |
A1 |
Dole, Douglas R. |
September 29, 2005 |
Pipe coupling having wedge shaped keys
Abstract
A coupling and pipes joined by the coupling are disclosed. The
pipes have circumferential grooves adjacent their ends which are
engaged by keys that project inwardly from the couplings. The keys
are wedge shaped and substantially fill the grooves to provide a
rigid joint. The grooves may have a shape that is complementary to
the grooves. The keys may have convex or concave cross sectional
shapes. The couplings have segments attached by fasters engaging
lugs at either end of the coupling. The lugs are attached pad to
pad or in spaced relationship. Gaps may be maintained between
various surfaces on the keys and on the grooves through tolerances
on the couplings.
Inventors: |
Dole, Douglas R.;
(Whitehouse Station, NJ) |
Correspondence
Address: |
SYNNESTVEDT & LECHNER, LLP
2600 ARAMARK TOWER
1101 MARKET STREET
PHILADELPHIA
PA
191072950
|
Assignee: |
Victaulic Company of
America
Easton
PA
|
Family ID: |
35064271 |
Appl. No.: |
11/091146 |
Filed: |
March 28, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60556962 |
Mar 26, 2004 |
|
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|
Current U.S.
Class: |
285/110 |
Current CPC
Class: |
F16L 21/065 20130101;
F16L 23/08 20130101; F16L 17/025 20130101; F16L 17/04 20130101;
F16L 25/12 20130101; F16L 43/00 20130101; F16L 23/22 20130101; Y10T
29/49948 20150115; B21D 17/04 20130101 |
Class at
Publication: |
285/110 |
International
Class: |
F16L 017/00 |
Claims
What is claimed is:
1. In combination, a pair of pipes and a coupling for connecting
said pipes end to end, said pipes having circumferential grooves
proximate to each said end, said coupling comprising a plurality of
segments positionable circumferentially around said pipes and means
for attaching said segments end to end, each of said segments
having a pair of keys projecting radially inwardly toward said
pipes for engagement with said circumferential grooves, said keys
being positioned in spaced apart relation from one another and
defining a space therebetween, said keys having a wedge-shaped
cross section, said grooves having a complementary shape to said
keys for receiving said keys when said segments are positioned
circumferentially around said pipes.
2. A combination according to claim 1, wherein at least two of said
segments have outwardly extending lugs at one end, said lugs
aligning with one another and being adapted to receive a fastener
for attaching said segments to one another end to end, said lugs
and fastener comprising said attachment means.
3. A combination according to claim 2, wherein one of said keys has
an inner surface facing said space and an outer surface facing away
from said space, said inner and outer surfaces being angularly
oriented relative to one another thereby defining said wedge-shaped
cross section of said one key.
4. A combination according to claim 3, wherein said outer surface
has a substantially flat cross-sectional profile.
5. A combination according to claim 3, wherein said inner surface
is oriented substantially perpendicularly to a longitudinal axis of
said pipes.
6. A combination according to claim 3, wherein said one key further
includes a radially facing surface positioned between said inner
and outer surfaces, said one key being sized so that when said lug
on one of said segments is engaged in pad to pad contact with said
lug on another of said segments, said radially facing surface and
said outer surface remain substantially in spaced relation away
from said pipe, said inner surface engaging said groove to connect
said pipes to one another.
7. A combination according to claim 3, wherein said one key further
includes a radially facing surface positioned between said inner
and outer surfaces, said one key being sized so that when said lug
on one of said segments is engaged in pad to pad contact with said
lug on another of said segments, said outer surface is positioned
in contact with said pipe and said radially facing surface is
positioned in spaced relation away from said pipe, said inner
surface engaging said groove to connect said pipes to one
another.
8. A combination according to claim 7, further comprising a
plurality of teeth positioned on said outer surface, said teeth
engaging said groove when said outer surface is positioned in
contact with said pipe.
9. A combination according to claim 3, wherein said one key further
includes a radially facing surface positioned between said inner
and outer surfaces, said one key being sized so that when said lug
on one of said segments is engaged in pad to pad contact with said
lug on another of said segments, both said radially facing surface
and said outer surface are positioned in contact with said pipe,
said inner surface engaging said groove to connect said pipes to
one another.
10. A combination according to claim 7, wherein said radially
facing surface has a substantially flat cross-sectional
profile.
11. A combination according to claim 6, wherein said spaced
relation between said radially facing surface and said pipe is no
greater than about 0.030 inches.
12. A combination according to claim 6, wherein said pipe ends are
separated apart from one another by a gap, said outer surface being
spaced apart from said pipe by a distance approximately equal to
1/2 of said gap between said pipe ends.
13. A combination according to claim 6, wherein said spaced
relation between said outer surface and said pipe is no greater
than about 0.035 inches.
14. A combination according to claim 3, wherein said one key
further includes a radially facing surface positioned between said
inner and outer surfaces, said one key being sized so that when
said lug on one of said segments is attached in spaced apart
relation to said lug on another of said segments, said radially
facing surface and said outer surface remain substantially in
spaced relation away from said pipe, said inner surface engaging
said groove to connect said pipes to one another.
15. A combination according to claim 3, wherein said one key
further includes a radially facing surface positioned between said
inner and outer surfaces, said one key being sized so that when
said lug on one of said segments is attached in spaced apart
relation to said lug on another of said segments, said outer
surface is positioned in contact with said pipe and said radially
facing surface is positioned in spaced relation away from said
pipe, said inner surface engaging said groove to connect said pipes
to one another.
16. A combination according to claim 3, wherein said one key
further includes a radially facing surface positioned between said
inner and outer surfaces, said one key being sized so that when
said lugs on one of said segments are attached in spaced apart
relation with said lugs on another of said segments, both said
radially facing surface and said outer surface are positioned in
contact with said pipe, said inner surface engaging said groove to
connect said pipes to one another.
17. A combination according to claim 15, wherein said radially
facing surface has a substantially flat cross-sectional
profile.
18. A combination according to claim 1, wherein one of said grooves
comprises: a first side surface positioned proximate to an end of
said pipe; a second side surface positioned in spaced apart
relation to said first side surface and distally to said end of
said pipe; a floor surface extending between said first and second
side surfaces; and wherein one of said first and second side
surfaces is oriented at an angle to said floor surface, said angle
being greater than 90 degrees.
19. A combination according to claim 18, wherein said second side
surface is oriented at said angle to said floor surface.
20. A combination according to claim 19, wherein said first side
surface is oriented substantially perpendicularly to said floor
surface.
21. A combination according to claim 1, further comprising a
sealing member positionable within said space between said keys,
said sealing member extending circumferentially around said pipes
to provide a fluid tight seal between said pipe ends.
22. A coupling for connecting two pipes together end to end, said
pipes having circumferential grooves proximate to each end, said
coupling comprising first and second segments positionable
circumferentially around said pipes, each said segment having
outwardly extending lugs at each end, said lugs of said first
segment aligning with said lugs of said second segment and being
adapted to receive fasteners for attaching said segments to one
another, each of said segments having a pair of keys projecting
radially inwardly toward said pipes for engagement with said
circumferential grooves, said keys being positioned in spaced apart
relation from one another and defining a space therebetween, each
of said keys having an inner surface facing said space and an outer
surface facing away from said space, said keys further including a
radially facing surface positioned between said inner and outer
surfaces, said keys being sized so that when said lugs on said
first segment are engaged with said lugs on said second segment, at
least one of said radially facing surfaces and said outer surfaces
remain substantially in spaced relation away from said pipes, said
inner surfaces engaging said grooves to connect said pipes to one
another.
23. A coupling according to claim 22, wherein both said radially
facing surface and said outer surface remain substantially in
spaced relation away from said pipes when said lugs on said first
segment are engaged with said lugs on said second segment.
24. A coupling according to claim 22, wherein said outer surface is
angularly oriented relative to said inner surface thereby defining
a wedge-shaped cross section of said keys.
25. In combination, a pair of pipes and a coupling for connecting
said pipes end to end, said pipes having circumferential grooves
proximate to each said end, said coupling comprising a plurality of
segments positionable circumferentially around said pipes, each of
said segments having a pair of keys projecting radially inwardly
toward said pipes for engagement with said circumferential grooves,
said keys being positioned in spaced apart relation from one
another and defining a space therebetween, said keys having a cross
sectional shape that substantially fills said grooves when said
segments are positioned circumferentially around said pipes.
26. A combination according to claim 25, wherein one of said keys
has a wedge shaped cross sectional shape.
27. A combination according to claim 26, wherein said one key has
an inner surface facing said space and an outer surface facing away
from said space, said outer surface being angularly oriented
relative to said inner surface thereby defining said wedge shaped
cross section of said one key.
28. A combination according to claim 27, wherein said outer surface
is oriented at an angle up to 70 degrees relatively to an axis
oriented coaxially with a longitudinal axis of said pipes.
29. A combination according to claim 25, wherein said keys have a
convexly curved cross sectional shape.
30. In combination, a pair of pipes and a coupling for connecting
said pipes end to end, said pipes having circumferential grooves
proximate to each said end, said coupling comprising a plurality of
segments positionable circumferentially around said pipes and means
for attaching said segments end to end, one of said segments having
a first key projecting radially inwardly toward one of said pipes
for engagement with said circumferential groove on said one pipe,
another of said segments having a second key projecting radially
inwardly toward the other of said pipes for engagement with said
circumferential groove on said other pipe, said keys having a
wedge-shaped cross section, said grooves having a complementary
shape to said keys for receiving said keys when said segments are
positioned circumferentially around said pipes.
Description
FIELD OF THE INVENTION
[0001] The invention concerns couplings for joining pipes end to
end and effecting a substantially rigid or flexible fluid tight
joint therebetween.
BACKGROUND OF THE INVENTION
[0002] Couplings for joining pipes together end to end comprise
arcuate segments that circumferentially surround co-axially aligned
pipes and engage circumferential grooves positioned proximate to
the ends of each pipe. The couplings are also used to connect pipes
to fluid control components such as valves, reducers, strainers,
restrictors, pressure regulators, as well as components to
components. Although in the description which follows pipes are
described, they are used by way of example only, the invention
herein not being limited for use only with pipes per se. It should
also be noted that the term "pipe" as used herein refers to
straight pipes as well as elbows, tees and other types of
fittings.
[0003] The segments comprising the couplings have circumferential
keys that extend radially inwardly toward the pipes and fit within
the grooves around the pipes. The keys are typically somewhat
narrower than the grooves to permit them to fit within the grooves
and bear against the shoulders formed by the grooves to hold the
pipes together against internal pressure and external forces that
may be applied to the pipes. External forces may arise due to
thermal expansion or contraction of the pipes due to changes in
temperature as well as the weight of the pipes or components such
as valves attached to the pipes, which can be significant for large
diameter pipes and valves. Wind loads and seismic loads may also be
a factor.
[0004] It is advantageous that pipe couplings be substantially
rigid, i.e., resist rotation of the pipes relative to one another
about their longitudinal axes, resist axial motion of the pipes
relatively to one another due to internal pressure, and resist
angular deflection of pipes relative to one another. A rigid
coupling will be less likely to leak, requiring less maintenance,
and will simplify the design of piping networks by eliminating or
at least reducing the need for engineers to account for axial
motion of pipes in the network when subjected to significant
internal pressure. Pipes joined by rigid couplings require fewer
supports to limit unwanted deflection. Furthermore, valves and
other components which may tend to rotate out of position because
their center of gravity is eccentric to the pipe axis will tend to
remain in position and not rotate about the longitudinal axis under
the pull of gravity when the pipe couplings are substantially
rigid.
[0005] Many couplings according to the prior art do not reliably
provide the desired degree of rigidity mainly because they use keys
having rectangular cross-sections that are narrower than the width
of the grooves that they engage. This condition may result in
inconsistent contact between the coupling and the pipes which
allows too much free play and relative movement, for example,
axially, rotationally or angularly, between the pipes. It is also
difficult to ensure that such keys properly engage the grooves.
Couplings which provide a more rigid connection may be ineffective
to force the pipe ends apart at a desired distance from one another
so that the keys and grooves are in proper alignment and the pipes
are properly spaced. When properly spaced apart, the pipe ends and
the coupling cooperate with a sealing member positioned between the
coupling and the pipe ends to ensure a fluid tight seal. The
movement of the pipes, although small, is effected as the couplings
are engaged with each other and the pipe and may required that
significant torque be exerted upon the fasteners used to clamp the
coupling to the pipes. This is especially acute when pipes to be
joined are stacked vertically one above another, and the action of
engaging the coupling with the pipes must lift one of the pipes
upwardly relatively to the other in order to effect the proper
spacing between the pipe ends. For such couplings, it is also
difficult to reliably visibly ensure that the couplings have been
properly installed so that the keys engage the grooves and the
pipes are spaced apart as required to ensure a fluid tight
seal.
[0006] It would be advantageous to provide a coupling that provides
increased rigidity while also reducing the force necessary to
engage the coupling with the pipe ends to effect their proper
spacing, and also provides a reliable visual indication that the
couplings are properly installed on the pipes.
SUMMARY OF THE INVENTION
[0007] The invention concerns a pair of pipes and a coupling for
connecting the pipes end to end. The pipes have circumferential
grooves proximate to each the end. The coupling comprises a
plurality of segments positionable circumferentially around the
pipes. Each of the segments has a pair of keys projecting radially
inwardly toward the pipes for engagement with the circumferential
grooves. The keys are positioned in spaced apart relation from one
another and define a space therebetween. The keys have a
wedge-shaped cross section. The grooves have a complementary shape
to the keys for receiving the keys when the segments are positioned
circumferentially around the pipes.
[0008] One of the keys has an inner surface facing the space and an
outer surface facing away from the space. The outer surface is
preferably angularly oriented relative to the inner surface thereby
defining the wedge-shaped cross section of the one key. Preferably,
the inner surface is oriented substantially perpendicularly to a
longitudinal axis of the pipes.
[0009] The one key further includes a radially facing surface
positioned between the inner and outer surfaces. The one key may be
sized so that when the lugs on one of the segments are engaged,
either in pad to pad contact or in spaced apart relation with the
lugs on another of the segments, the radially facing surface and
the outer surface remain substantially in spaced relation away from
the pipe, the inner surface engaging the groove to connect the
pipes to one another.
[0010] In another embodiment, the outer surface is positioned in
contact with the pipe, the radially facing surface is in spaced
relation away from the pipe, and the inner surface again engages
the groove to connect the pipes to one another. In an additional
embodiment, the outer surface is in spaced relation away from the
pipe and the radially facing surface is in contact as well as the
inner surface. Alternately, the one key may be sized so that when
the lugs on the one segment are engaged in either pad to pad
contact or spaced apart relation with the lugs on the other
segment, both the radially facing surface and the outer surface are
positioned in contact with the pipe, the inner surface engaging the
groove to connect the pipes to one another.
[0011] Preferably, one of the grooves comprises a first side
surface positioned proximate to an end of the pipe. A second side
surface is positioned in spaced apart relation to the first side
surface and distally to the end of the pipe. A floor surface
extends between the first and second side surfaces. One of the
first and second side surfaces is oriented substantially
perpendicularly to the floor surface.
[0012] The invention further includes coupling for connecting two
pipes together end to end. The pipes have circumferential grooves
proximate to each end. The coupling comprises first and second
segments positionable circumferentially around the pipes. Each
segment has outwardly extending lugs at each end. The lugs of the
first segment align with the lugs of the second segment and are
adapted to receive fasteners for attaching the segments to one
another. Each of the segments has a pair of keys projecting
radially inwardly toward the pipes for engagement with the
circumferential grooves. The keys are positioned in spaced apart
relation from one another and define a space therebetween. Each of
the keys has an inner surface facing the space and an outer surface
facing away from the space. The keys further include a radially
facing surface positioned between the inner and outer surfaces. The
keys are sized so that when the lugs on the first segment are
engaged with the lugs on the second segment, at least one of the
radially facing surfaces and the outer surfaces remain
substantially in spaced relation away from the pipes, the inner
surfaces engaging the grooves to connect the pipes to one
another.
[0013] The invention also concerns a pair of pipes and a coupling
for connecting the pipes end to end. The pipes have circumferential
grooves proximate to each the end. The coupling comprises a
plurality of segments positionable circumferentially around the
pipes. Each of the segments has a pair of keys projecting radially
inwardly toward the pipes for engagement with the circumferential
grooves. The keys are positioned in spaced apart relation from one
another and define a space therebetween, the keys having a cross
sectional shape that substantially fills the grooves when the
segments are positioned circumferentially around the pipes. In one
embodiment, the keys have a convexly curved cross sectional
shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a perspective view of a coupling for connecting
two pipes end to end, the pipes being shown in phantom line;
[0015] FIG. 1A is a perspective view showing a detail of the
coupling depicted in FIG. 1;
[0016] FIG. 2 is an exploded perspective view of the pipe coupling
shown in FIG. 1;
[0017] FIG. 2A is an exploded perspective view of an alternate
embodiment of a pipe coupling according to the invention;
[0018] FIG. 2B is a perspective view of a portion of FIG. 2 shown
on an enlarged scale;
[0019] FIG. 3 is a side view of a segment comprising the coupling
shown in FIG. 1;
[0020] FIG. 4 is a bottom view of the segment shown in FIG. 3;
[0021] FIG. 4A is a side view of an alternate embodiment of a
segment having one key and a flange for mating with flanged pipes
or fittings;
[0022] FIG. 5 is a cross-sectional view taken at line 5-5 of FIG.
1;
[0023] FIGS. 5A and 5B are cross sectional views taken at line 5-5
of FIG. 1 showing alternate embodiments of the coupling according
to the invention;
[0024] FIGS. 6 and 7 are side views of a roller tool forming a
groove in a pipe;
[0025] FIGS. 7A-7G show side views of various embodiments of roller
tools for forming a groove in a pipe;
[0026] FIG. 8 is a cross-sectional view of an alternate embodiment
of the coupling;
[0027] FIG. 9 is a partial perspective view of an alternate
embodiment of a coupling according to the invention;
[0028] FIGS. 10-15 are longitudinal sectional views of embodiments
of pipes having circumferential grooves according to the invention;
and
[0029] FIGS. 16-21 illustrate various fittings and components
having circumferential grooves according to the invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0030] FIG. 1 shows a pipe coupling 10 for connecting two pipes 12
and 14 co-axially end to end. As shown in FIG. 2, coupling 10 is
comprised of at least two segments 16 and 18. Each segment 16 and
18 has lugs 20 and 22 respectively, the lugs being positioned at or
proximate to each end of the segments. The lugs 20 at each end of
segment 16 align with the lugs 22 at each end of segment 18. Lugs
20 and 22 are adapted to receive fasteners, preferably in the form
of bolts 24 and nuts 26 for joining the segments to one another end
to end surrounding the pipes 12 and 14. In one embodiment, shown in
FIG. 1, the lugs 20 engage the lugs 22 in what is known as
"pad-to-pad engagement" with the lugs contacting one another when
the segments 16 and 18 are properly engaged with the pipes 12 and
14 as explained below. The lugs may also be attached to each other
in spaced apart relation when the segments 16 and 18 are properly
engaged with the pipes 12 and 14, as illustrated in FIG. 1A.
[0031] Although lugs are the preferred means for attaching the
segments to one another end to end, it is recognized that there are
other attachment means, such as circumferential bands, axial pins,
and latching handles. These means are disclosed in U.S. Pat. Nos.
1,541,601, 2,014,313, 2,362,454, 2,673,102, 2,752,174, 3,113,791,
and 4,561,678, all of which are hereby incorporated by
reference.
[0032] For large diameter pipes, it is sometimes advantageous to
form the coupling 10 from more than two segments. As shown in FIG.
2A, pipe coupling 10 comprises segments 16a and 16b joined to each
other and to segments 18a and 18b, also joined to one another. Each
segment again preferably has lugs 20 and 22 at each end thereof,
the segments being joined to one another end to end by fasteners
such as bolts 24 and nuts 26. The following description of the
coupling 10 is provided by way of example, and is based upon a
coupling having two segments with lugs at either end. Various
aspects of the description are applicable to alternate embodiments
regardless of the number of segments comprising the coupling or the
manner in which the segments are attached to one another.
[0033] As shown in FIG. 2, each segment 16 and 18 has an arcuate
surface 28 facing inwardly toward pipes 12 and 14. A pair keys 30
project radially inwardly from the arcuate surface 28. Keys 30 on
each segment are in spaced apart relation to one another and define
a space 32 between them. As best shown in FIG. 5, to effect the
connection between pipes 12 and 14, keys 30 engage grooves 34 and
36 extending circumferentially around pipes 12 and 14 respectively.
Engagement of keys 30 with grooves 34 and 36 substantially rigidly
connect the pipes 12 and 14 coaxially to one another and maintain
them at a predetermined separation as indicated by the gap 38. A
sealing member 40 is positioned within space 32 and between the
arcuate surfaces 28 of segments 16 and 18 and the pipes 12 and 14.
The gap 38 between the pipes 12 and 14 provides tolerance
facilitating mounting of the coupling and allows pressurized fluid
to apply hydraulic pressure to the sealing member 40 and ensure a
fluid tight seal between the pipes 12 and 14.
[0034] As best shown in FIGS. 2 and 3, each key 30 preferably has a
pair of camming surfaces 42 positioned adjacent to lugs 20 and 22
or otherwise near the ends of the segments. Camming surfaces 42
preferably face outwardly away from space 32 and are angularly
oriented, as shown in FIG. 2B, with respect to an axis 43 oriented
substantially tangential to the key 30. The camming surfaces have
an angular orientation 45 that forms a wedge 46 adjacent to each
lug, also shown in FIG. 4. As the segments 16 and 18 are brought
into engagement with grooves 34 and 36 to connect pipe 12 to pipe
14 as illustrated in FIG. 5, the camming surfaces 42 (see FIG. 2)
are the first surfaces to engage the grooves 34 and 36. The wedge
46 formed by the camming surfaces 42 provides a mechanical
advantage which forces the pipes 12 and 14 apart from one another
as the lugs 20 and 22 of segments 16 and 18 are brought toward one
another, preferably into pad-to-pad engagement. This wedging action
ensures that a separation gap 38 between the pipe ends (see FIG. 5)
will be achieved when the connection between the pipes 12 and 14 is
effected while reducing the force required to bring the lugs 20 and
22 toward each other. Lugs 20 and 22 are normally drawn toward each
other by tightening nuts 26 (see FIG. 1). The mechanical advantage
obtained by the use of wedge 46 significantly reduces the torque
applied to nuts 26 needed to bring the lugs 20 and 22 into
pad-to-pad engagement to separate the pipes 12 and 14 by the gap
38, and thereby allows large diameter, heavy pipes to be manually
connected, even when stacked vertically above one another. Such
configurations are a particular problem as the insertion of the
keys 30 into the grooves 34 and 36 must lift the entire weight of
the pipe to form the gap 38. The wedge 46 makes this effort
significantly easier. Preferably, as shown in FIG. 2B, the angular
orientation 45 of camming surfaces 42, as measured with respect to
axis 43, is preferably about 50, but may be up to about 100 for
practical designs.
[0035] The use of keys having camming surfaces is not confined to
couplings for joining grooved pipes to one another, but may be used
on practically any coupling arrangement having at least one key.
FIG. 4A shows a coupling segment 51 used in conjunction with a
similar coupling segment to attach grooved pipe to flanged pipe.
Coupling segment 51 has an arcuate key 30 with camming surfaces 42
at either end. As described above, the camming surfaces may be
angularly oriented tangentially with respect to the key 30 and form
a wedge 46 as shown in FIG. 4. Opposite the key is a flange 53
adapted to engage a mating flange on a flanged pipe. The flanges
are secured via fasteners that pass though bolt holes 55 as is
understood for flanged connections. The coupling segment 51 is
attached end to end to its associated coupling segment by
attachment means, preferably lugs 20 positioned near the ends of
the segment that align and are engaged by fasteners as is
understood in the art and described above.
[0036] As best shown in FIGS. 5 and 5A, keys 30 preferably have a
shape that will effect a wedging action when they engage grooves 34
and 36. FIG. 5 illustrates one configuration wherein keys 30 have a
wedge-shaped cross section. The keys 30 are defined by an inner
surface 50 facing space 32, an outer surface 52 facing outwardly
away from space 32, and a radial surface 54 positioned between the
inner and outer surfaces and facing radially inwardly toward the
pipes engaged by the coupling. Preferably, the inner surface 50 is
oriented substantially perpendicularly to the axis 48 and outer
surface 52 is oriented angularly relative to the axis 48 so as to
form the wedge-shaped cross section of keys 30. The relative angle
56, measured radially with respect to the key between the outer
surface 52 and an axis 48 oriented substantially co-axially with
the longitudinal axes of pipes 12 and 14, ranges up to about
70.degree., although 50.degree. is preferred (see also FIG. 1).
[0037] Although surfaces 52 and 54 in FIG. 5 are shown in
cross-section as having a straight profile, they may be, for
example, convex, concave or have some other profile shape and still
effect a wedging action when engaged with grooves 34 and 36. An
alternate embodiment of keys 30 is illustrated in FIG. 5A wherein
surface 50 has a curved cross sectional profile in the form of a
convex radius that substantially blends into radial surface 54.
[0038] As shown in FIG. 4, it is preferred that the radial angular
orientation 44 of camming surfaces 42 be substantially equal to the
radial angular orientation 56 of the key outer surface 52 as
measured relatively to the longitudinal axis 48. It is advantageous
to match the radial orientation angles of the camming surfaces 42
and the key outer surfaces 52 with one another to avoid point
contact when the surfaces engage facing surfaces of the grooves 34
and 36 as the coupling is installed in order to mitigate gouging
between the surfaces that results from point to point contact.
[0039] Preferably, the grooves 34 and 36 that keys 30 engage have a
shape that is complementary to the wedge-shape cross section of the
keys. In general, it is advantageous that the keys have a cross
sectional shape that substantially fills the grooves even when the
shapes of the groove and key are not exactly complementary. Groove
36 is described in detail hereafter, groove 34 being substantially
similar and not requiring a separate description. Groove 36 is
defined by a first side surface 58 positioned proximate to end 14a
of pipe 14, a second side surface 60 positioned in spaced apart
relation to the first side surface 58 and distally from the end
14a, and a floor surface 62 that extends between the first and
second side surfaces. The complementary shape of the groove 36 to
the keys 30 is achieved by orienting the floor surface 62
substantially parallel to the radial surface 54, orienting the
first side surface 58 substantially perpendicularly to the floor
surface 62 (and thus substantially parallel to the inner surface
50), and orienting the second side surface 60 substantially
parallel to the outer surface 52 (and thus angularly to the floor
surface 62).
[0040] Preferably, the keys 30 and the lugs 20 and 22 are sized and
toleranced so that when the lugs 20 are in pad-to-pad engagement
with the lugs 22, i.e., in contact with each other as shown in FIG.
1, the keys 30 engage the grooves 34 such that the keys' outer
surface 52 is either just contacting the second side surface 60 in
what is called "line-on-line clearance" (see the left half of FIG.
5), or is in spaced relation to the second side surface 60 of the
groove, as defined by a gap 64 no greater than 0.035 inches (shown
on the right half of FIG. 5. Furthermore, the radial surface 54 is
also in either line on line clearance with the floor surface 62
(left half, FIG. 5), or in spaced relation to floor surface 62, as
defined by a gap 66 no greater than 0.030 inches (right half, FIG.
5). The inner surface 50 is nominally in contact with the first
side surface 58 as shown in FIG. 5, but there may be a gap there as
well for certain tolerance conditions. As a practical matter,
however, it is difficult and costly to make pipes and couplings
perfectly round and to the exact dimensions desired, so that there
will be intermittent contact between various surfaces of the keys
30 and grooves 34 and 36 circumferentially around any pipe joint,
creating an effectively rigid joint. Joint rigidity may be further
augmented by the use of teeth 31 that project outwardly from the
various surfaces of keys 30 as best shown in FIG. 2. Teeth 31 bite
into the groove surfaces of the pipes, augmenting friction to help
prevent rotational displacement of the pipes relatively to the
couplings. The same relationships between the various surfaces
mentioned above may also be achieved when the lugs are attached to
one another in spaced apart relation as shown in FIG. 1A.
[0041] Analogous relationships between the key surfaces and the
surfaces comprising the grooves are contemplated even when the keys
do not have a shape complementary to that of the groove, as shown
in FIG. 5A. Couplings having such keys, for example, the convex
shaped key 30, may have surfaces 52 that just contact the second
side surface 60 in line on line clearance (left side, FIG. 5A), or
be in spaced relation to surface 60 (right side, FIG. 5A), having a
gap 64 between the surfaces 52 and 60 of about 0.035 inches. Again,
surfaces 54 and 66 may also be in line on line clearance or may be
separated by a gap 62, preferably no greater than 0.030 inches.
[0042] Alternately, as shown in FIG. 5B, wedging action of keys 30
may also be ensured when inner surface 50 and outer surface 52
contact groove surfaces 58 and 60, respectively, but radial surface
54 is in spaced relation to the groove's floor surface 62 with a
gap 66. The right side of FIG. 5B shows various straight sided key
surfaces 50, 52 and 54 and counterpart straight sided groove
surfaces 58, 60 and 62 giving the groove and the key substantially
complementary shapes. The left side of FIG. 5B shows a convexly
curved outer surface 52 engaging a straight surface 60, as an
example wherein the shape of the key and the groove are not
substantially complementary. Note that groove floor surface 62 is
shown on the left side to be angularly oriented with respect to the
surface of pipe 12.
[0043] It is found that the preferred configuration defined by
pad-to-pad engagement of lugs 20 and 22 in conjunction with the
tolerance conditions as describe above provides several advantages.
The engagement of inner surface 50 with first side surface 58
forces pipes 12 and 14 into substantially precise axial position
relative to one another. Because these surfaces bear against one
another when the coupling is installed on the pipes they will not
shift axially when internal fluid pressure is applied. Thus,
designers need not take into account lengthening of the piping
network due to internal pressure during use, thereby simplifying
the design. The relatively small gaps 64 and 66 (which could be
zero) ensure adequate rigidity and prevent excessive angular
displacement between the pipes and the couplings, while the
tolerances necessary to limit the gaps within the desired limits
allow the coupling 10 to be manufactured economically. It also
allows the grooves in the pipes, valves or other fittings to be
manufactured economically. The gaps work advantageously in
conjunction with the normally encountered out of roundness of
practical pipes to provide a rigid joint. The pad-to-pad engagement
of lugs 20 and 22 provides a reliable visual indication that the
coupling 10 is properly engaged with the pipes 12 and 14.
[0044] If it is desired to have a more flexible coupling 10 to
allow greater angular deflection, then the gaps 64 at one or both
ends of the coupling may be made larger than the aforementioned
limit of 0.035 inches. For flexible couplings, it is found
advantageous to have gap 64 between surfaces 52 and 60 preferably
be 1/2 of the size of gap 38 between the ends of pipes 12 and 14 as
shown in FIG. 5.
[0045] It is also feasible to have keys 30 engage grooves 34 and 36
without a gap under all tolerance conditions. This configuration
takes advantage of the wedging action of the keys to provide a
rigid joint. It is not practical, however, to have this
configuration and also maintain pad to pad engagement of lugs 20
and 22 because it is very difficult to economically manufacture
couplings and pipes to the necessary tolerances to ensure both pad
to pad engagement and full contact circumferential wedging
engagement of the keys and grooves. For the configuration wherein
pad-to-pad engagement is not nominally held, as shown in FIG. 9, it
is preferred to employ a tongue 110 adjacent to the lug 20 on
segment 16 that fits into a recess 112 adjacent to lug 22 on
segment 18. The tongue prevents sealing member 40 from blowing out
through a gap between the lugs 20 and 22 when the joint is
subjected to high internal pressure.
[0046] As illustrated in FIG. 6, groove 36 is advantageously formed
by cold working the material forming pipe 14. In a preferred
embodiment, groove 36 comprises a first side surface 37 positioned
proximate to the end of pipe 14, a second side surface 60
positioned in spaced apart relation to the first side surface and
distally to the end of the pipe, and a floor 41 that extends
between the first and second side surfaces. Preferably, the second
side surface is angularly oriented relatively to the floor at an
angle 43 that is than 90 degrees.
[0047] A roller tool 68 is used having a cross sectional shape at
its periphery substantially identical to the desired shape of the
groove. The roller tool 68 is forcibly engaged with the outer
surface 70 of pipe 14 around its circumference, either by moving
the roller tool around the pipe or moving the pipe about its
longitudinal axis 48 relatively to a roller tool. Preferably, a
back-up roller 72 engages the inner surface 74 of the pipe 14
opposite to the roller tool 68. The pipe wall 76 is compressed
between the roller tool 68 and the back-up roller 72. Use of the
back-up roller 72 provides a reaction surface for the roller tool.
The back-up roller also helps ensure that accurate groove shapes
are achieved by facilitating material flow during roll
grooving.
[0048] During cold working to form the groove 36 having the
angularly oriented second side surface 60, it is found that
significant friction is developed between the roller tool 68 and
the pipe 14. The friction is caused by the contact between the
angled surface 78 on the roller tool 68 that forms the angularly
oriented second side surface 60 of groove 36. Because it is angled,
points along angled surface 78 are at different distances from the
axis of rotation 80 of roller tool 68. Due to their different
distances from the axis 80, each of the points on the surface 78
will move relative to one another at a different linear speed for a
particular angular velocity of the roller tool 68. The points
farthest from the axis 80 move the fastest and the points closest
to the axis move the slowest. Thus, there is a velocity
differential along the angled surface 78 which causes the surface
to slip relatively to the second side surface 60 of groove 36 as
the roller tool 68 rotates relatively to the pipe 14 to form the
groove. The relative slipping between the roller tool and the pipe
causes the friction. Excessive heat caused by the friction can
result in a break down of the roller tool bearing lubricants and
make the roller tool too hot to handle when changing tools for a
different size pipe. The roller tool must be allowed to cool before
it can be changed, resulting in lost time.
[0049] To mitigate the generation of excessive heat, the roller
tool 82, shown in FIG. 7, is used to form a groove 84 in pipe 14.
In groove 84, the second side surface 86 has a first surface
portion 88 oriented angularly relative to the floor surface 90, and
a second surface portion 92, positioned adjacent to the floor
surface 90 and oriented substantially perpendicular to it, thereby
reducing the size of the angularly oriented second side surface 86.
By reducing the size of the angled surface regions on both the
roller tool 82 and the groove 84 the friction caused during cold
working to form the groove is reduced. The first surface portion
88, being angularly oriented, still provides the advantages as
described above for the second side surface 60. An example of a
coupling 10 engaging a groove 84 is shown in FIG. 8.
[0050] The roller tool 82 has a circumferential surface 94 with a
cross sectional shape complementary to groove 84, the shape
comprising a first perimetral surface 99 oriented substantially
perpendicularly to the axis of rotation 80 of roller tool 82, a
second perimetral surface 98 positioned in spaced relation to the
first perimetral surface 96 and oriented substantially
perpendicular to the axis 80, a radial surface 100 extending
between the first and second perimetral surfaces and oriented
substantially parallel to axis 80, and an angled surface 102
positioned adjacent to perimetral surface 100 and oriented
angularly to the axis 80. The angled surface 102 is preferably
oriented up to about 70.degree. relatively to axis 80, and most
preferably at about 50.degree.. Surface 102 slopes away from the
second perimetral surface, thereby making contact with the pipe
when forming the groove 84.
[0051] Wedging action between the keys 30 and grooves in the pipes
can be achieved for groove cross sectional shapes other than those
described above. The main criterion for wedging action is that the
width of the groove at the surface of the pipe be greater than the
width of the groove at the floor of the groove. FIGS. 10-15 show
various groove configurations meeting this criteria. FIG. 10 shows
a groove 114 partially defined by a side portion 116 having a
concave cross sectional shape. FIG. 11 shows a groove 118 partially
defined by a side portion 120 having a convex cross-sectional
shape. In FIG. 12, the groove 122 is partially defined by a side
portion 124 having first and second angled portions 124a and 124b,
the first angled portion 124a having a greater slope than the
second angled portion 124b. FIG. 13 shows a groove 126 partially
defined by a side portion 128 having a first angled portion 128a
with a slope less than the second angled portion 128b. Combinations
of radius and angled portions are also feasible, as shown in FIG.
14, wherein groove 130 has a radius portion 132 and an angled
portion 134. FIG. 15 illustrates an example of a groove 136 having
a wedge-shaped cross sectional profile, there being no floor
portion of any significance as compared with the other example
grooves. The groove 136 is defined by side portions 136a and 136b
oriented angularly with respect to one another. Common to all of
the designs is the characteristic that the width 138 of the groove
at the surface of the pipe is greater than the width 140 of the
groove at the floor of the groove. Note that, although it is
preferred that the floor be substantially parallel to the pipe
surface, it may also be curved, as shown in FIG. 10, or
non-existent, as shown in FIG. 15, which has no floor, the floor
width being essentially zero. The floor may also be angularly
oriented as shown in FIG. 5B.
[0052] Roller tools for creating grooves as described above are
shown in FIGS. 7A-7G. In FIG. 7A, roller tool 101 is rotatable
about axis 80 and has a radially facing surface portion 103 flanked
by a first surface portion 105 and a second surface portion 107.
Roller surface portion 105 is preferably oriented perpendicularly
to axis 80 and results in the formation of a substantially vertical
groove side surface. Roller surface portion is concave and results
in the convex groove side surface 120 as shown in FIG. 11.
[0053] Similarly, roller tool 109, shown in FIG. 7B, has a radially
facing surface portion 111 extending between a perpendicular
surface portion 113 and a convex surface portion 115. Such a roller
produces a groove with a concave side surface 116 as shown in FIG.
10.
[0054] Additional roller embodiments 117 and 119, shown in FIGS. 7C
and 7D, each have a surface portion 121 with a first face 123
angularly oriented with respect to axis 80, and a second face 125,
also angularly oriented with respect to axis 80, but at a different
angle. In roller tool 117, the slope of the first surface portion
is greater than the slope of the second surface portion, and this
roller produces a groove 122 as shown in FIG. 12. In roller tool
119, the slope of the first surface portion is less than the slope
of the second surface portion, and this roller produces a groove
126, having an angularly oriented side surface 124 as shown in FIG.
13.
[0055] Roller tool 127, shown in FIG. 7E, has no radially facing
surface, an angled surface 129 intersects with a surface portion
131 that is substantially perpendicular to the axis of rotation 80.
Roller tool 127 is useful for creating the groove shown in FIG.
15.
[0056] Roller tool 133, shown in FIG. 7F, has a curved radially
facing surface 135 and an angularly oriented surface 135 as well as
a perpendicular surface 137. The curved surface may be convex,
concave, sinusoidal, hyperbolic, or irregularly curved.
[0057] As shown in FIG. 7G, the roller 139 may have a radially
facing surface 141 that is angularly oriented with respect to the
axis of rotation 80. A groove as shown in FIG. 5B is produced by
such a tool.
[0058] While grooves adapted to achieve significant wedging action
with the keys of a coupling have been described applied to pipe
ends, such grooves may also be used in conjunction with pipe
fittings as well. For example, FIG. 16 shows an elbow fitting 140
having circumferential grooves 142 at either end. Grooves 142 may
have any of the cross sectional profiles illustrated in FIGS. 5 and
10-15 or their variations as described above. Similarly, the Tee
fitting 144 shown in FIG. 17 has grooves 146, preferably adjacent
to each of its ends, the grooves being adapted to develop wedging
action to couple the fitting to pipes or other fittings as
described herein. FIG. 18 shows a fitting 148 having a wedging
groove 150 adjacent to one end and a flange 152 at the opposite
end. Fitting 148 allows a piping network using mechanical couplings
to be joined to another network coupled using flanges. Furthermore,
as illustrated in FIGS. 19 and 20, other types of fittings such as
a reducer 154 (FIG. 19) used to join pipes having different
diameters, or a nipple 156 (FIG. 20) may also benefit from having
respective grooves 158 and 160 that are like those illustrated and
described above that increase the wedging action between the
coupling and the groove to ensure either a stiffer or more flexible
joint, depending upon the tolerances of the coupling as described
above.
[0059] As further shown in FIG. 21, components related to control
of fluid flow, such as a valve 162 may also have grooves 164 that
are like those described above to couple the valve to pipes,
fittings or other components using mechanical couplings as
described herein.
[0060] Pipe couplings according to the invention incorporate the
advantages of a rigid connection with a reliable visual indicator
for confirming that the coupling properly engages the pipes to
effect a fluid tight joint. The couplings have tolerances allowing
them to be economically produced and still yield a substantially
rigid joint between pipes.
* * * * *