Note: Descriptions are shown in the official language in which they were submitted.
2 ~
TJ~S IN~NTION relates to pipe ~oint6 and is particularly,
but not exclusively, applicable to the formation of ~oints
between rigid thermo-plastics material.
It i8 known to effect joints between the ends of rigid
5 thermc-plastics pipes in ~arious ~ays, for example by th~
use of solvent cements or by fitting injection moulded end
fittings to the pipes, and ~oining the pipe~ by securing
the respective end fittings together by appropriate Recur-
ing means.
The use of solvent cements to form joints between
rigid thermo-plastics pipes prevents subsequent disassembly
Or the parts cemented to~ether without dama6re, entails an
inevi~able lapse Or time before a joint is ready for ser~ice
and is not practicable with some types of thermo-plastics
materials. ~urthermore, unless end fittings are employed,
it is difficult to provide, by the use of sol~ent cements~
an end-to-end joint between thermo-plastics pipes of the
same diameter 1~hich has adequate strength to resist axial
forces between the pipes connected or to resist tra~sverse
bending forces applied to a ~oint. The use o~ injcction
moulded end fittin~s may avoid this disadvantage but of
course entalls additional e~pense.
It ~8 ~n object of the present invention to provide an
improved pipe ioint by means of which the above noted dis-
2~ advantages may be a~oided and which is simple and economicalin construction. According to the invention there is provided a mechanical
pipe joint comprising,
a first pipe having an end portion affording one end of
the first pipe,
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a ~econd pipe having an end portion within which said end
portion of said first pipe is snugly received, said end portion
of said second pipe affording one end of said second pipe,
each ~a~d pipe having, on ~ts exter~or, an annular rib
extending around the pipe and coaxial therewith, each said rib
being at a location spaced from the end of the respective pipe
afforded ~y the respective end portion,
the joint further including a clamping ring encircling the
two pipes and spanning said annular rib~ of the two pipes, a
respective flange, extending toward the axis of the pipes being
provided at each of the two axial ends of t~e clamping ring,
each said flange engaging t~at flank of a respective one
of said annular ri~s which is furthest from the other of said
annular ri~s,
each said pipe ha~ing an internal annular groove at an
axial pos~tion corresponding to the external annular rib thereon,
said end portion of said first pipe extending at least
partly across said annular groove ~n said second pipe to define
an annular space ~etween a wall of said annular groove in said
sec~nd pipe and the adjacent part of the exterior of said end
portion of the first pipe,
and an annular seal disposed in said annular space.
The clamping ring is preferably formed of two arcuate
parts flexi~ly connected at their one ends~ for example by
a hinge arrangement and provided at their other ends with
formations which, in the assembled ~oint, are engaged by a
channel-shaped wed~ring mcmber slid over said formations
in a direction substantially parallel ~Yith the longitudinal
axes of the pipes at the Joint.
The flanks of said annular ribs engaged by the ~lan~es
of the clamping ring are preferably inclined with resp~ct
to the ax~3 of the pipe joint and the flanges of the
clamping ri~g correspondingly inclined in such a way that
a circumferential clamping forcc applicd to the clamping
ring acts to wedge the two pipes towards each other.
An embodiment of the invention is described below with
reference to the accompanying drauin~s in which:
~ igure 1 is a vicw in a~ial scction o~ a pipe joint
cmbod~ri~r thc i~lvnntion,
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Figure 2 i8 a view in half axial ~ection of a modified
pipe ~oint embodying the invention,
Figure 3 i~ a cro B ~ - sectional view, as seen along the
line III-III in Figure 1, of the clamping ring and wedging
member only, forming part of the pipe ~oint of ~igures 1
and 2, and
Figure 4 i9 a side elevation view of a wedging member
used to secure the clamplng ring.
Referring to Figure 1, a joint between the ends of two
cylindrical pipes 10 and 12 of rigid thermoplastics material
i~ effected by deforming respective end portions of the
pipes 10 and 12, whilst softened under the action of heat~
to the respective forms shown, 80 that the pipe 12 has a
cylindrical end portion 14 which i~ of the same diameter as
the ma~or portion of the pipe 12 and is separated from the
major portion of the pipe 12 by an annular deformation 15
while the pipe 10 ha~ a cylindrical end portion 16 of a
diameter greater than that of the ma~or part of the pipe 10
and having an internal dlameter such that the end portion
14 can be fitted snugly within the end portion 16 as shown
in ~igure 1. The end portion 16 is separated from the ma~or
portion of the pipe 10 by an annular deformation 17.
Each of the annular deformations 15, 17 provides, on
the exterior of the respective pipe 12, 10, a respective
annular rib having at it~ crest an axially ~hort cylindrical
external surface substantially coaxial with the pipe and
conically sloping flanks extending re~pectively from the
crest to the cylindrical surface of the major part of the
pipe and from the crest towards the respective end portion
1~ or 16. Similarly, each annular deformation 15, 17 pro-
vides on its interior an annular groove of a form comple-
mentary with that of the rib on the exterior of the
respective pipe.
Thus each said annular groove comprise~ an axially
short ~urface which is cylindrical about the axis of the
re~pective pipe 10, 12 and forms the bottom of the groove,
and conically inclined walls extending respectively from
1 1C~5S20
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the bottom of the groo~e to the major portion of the
re~pectl~e pipe and to the end portion of the respective
pipe In ~igure 1, the bottom of the groove provided by
deformation 17 i8 indicated at 24, the conically inclined
wall extending to the major portion of tube 10 is indicated
at 26 and the conically inclined wall extending to the end
portion 14 i8 indicated at 22.
It will be noted that the annular deformation 15 on the
pipe 12 provides, in the region of the transition from the
end portion 14 to the annular deformation 15, a radially
extending shoulder 20 on the exterior of the pipe and facing
towards the free end of the end portion 14. The free end
of the end portion 16 of pipe 10 abuts this shoulder 20
to limit movement of the pipes 10 and 12 towards each other
as shown in Figure 1.
The relati~e lengths of the end portions 14 and 16 are
such that~ in the position shown in Figure 1, the end portion
14, on the lnterior of the pipe 10, 0xtends partially over
the annular groove provided by the deformation 17 and, in
particular, extend~ over the conically inclined wall 22 of
thi~ groove, further extends over the bottom 24 of this
grooYe and partly oYer the other conically inclined wall 26
of thi~ groove. There is thus defined between the end part
of the end portion 14 and the groove provided by the annular
deformations 17 an annular recess in which is accommodated
an a~nular elastomeric seal 28 which is generally U-shaped
in half axial ~ection with the channel defined between the
arms of the U facing toward~ the conically sloping wall 26.
The radially outer arm of the U fit~ snugly against the
bottom 24 of the groove provided by deformation 17 whilst
the other limb of the U bears snugly again~t the cylindrical
external surface of the end portion 14.
The two pipes 10 and 12 are held together in the joint
by a clamping ring 30 which extends around the joint and
spans both defo~mations 15 and 17. Referring to Figure 3,
the clamping ring 30 compri~es two similar arcuate parts
30a and 30b which are formed as pressings in sheet steel
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and which are pivotally connected by a hinge arrangement
40. Each said arcuate part includes a ma~or, part cyllndri-
cal portion 32, the axls of curvature of the part cylindri-
cal portion being parallel wlth the pivotal axis of hinge
arrangement 40, the axeR of curvature of portions 32 being
coincident in the position shown in Figure 3 and being
indicated at 31 in Figure 3.
Over the ma~or part of the angular extent of each
portion 32 about its axis of curvature, part conical flanges
34, 36 are provided at axially extreme ends of the portion
32, the axis of curvature of these part conieal flanges
corresponding with that of the re~pective portion 32, and
the flanges 34, 36 extending from the respective portion 32
towards the axis of curvature of the latter.
Thus each arcuate part 30a, 30b provides on its concave
side, a segment of an annular channel about the axis of
curvature of the respective portion 32, the channel being
open toward~ the last mentioned axis. When the clamping
ring i8 in its closed position around the pipes 10, t2~
the axes of curvature of the portions 32 of the part~ 30a,
30b substantially coincide with each other and with the axis
of the pipes 10, 12 so that the parts 30a, 30b provid~
respective segment~ of the same annular channel about the
axis of the ~oint and which cha~nel receives the ribs
provided by annular deformation~ 15 and 17. A~ ~how~ in
Figure 1, the major part of the axial length of the clamping
ring is provided by the cylindrical portions 32, which ln
the assembled joint are sub~ta~tially coaxial with the pipes
10 and 12, extend from the deformation 15 to the deformation
17 and are spaced radially outwardly therefrom, the conically
inclined flanges 34 and 36, bearing against the ribs provided
by deformations 15 and 17 re~pectively. The flange 36 has
the same inclination with respect to the axis of the pipe
joint as tne 510ping flank of the deforma'ion 17 which is
furthest from the defo~mation 15 and bears against the
extsrnal surface provided by the las* mentioned flank.
S~milarly, the flange 34 has the same inclination as that
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flank of the annular deformation 15 which i5 furthest from
the deformation 17 and the flange 34 beara against the
e~ternal surface presented by the lnst mentioned flank. It
wlll be appreciated that by virtua of the inclination of
the flange~ 34, 36 and the flank~ of the deformations 15,
17 against which they bear, a circumferential tens$on in
the clamping ring 30 will give rise to forces urging the
end portion 14 further into the pipe 10 and thus urging the
end face of the end portion 16 towards engag~ment with the
shoulder 60. Thus forces urging the pipes 1~ and 12 axially
towards each other are absorbed compressively by abutment of
the end face of portion 16 with the shoulder 20 whilst
forces tending to separate the pipe~ 10 and 12 ~xially are
absorbed by the steel clamping ri.ng 30.
Referring again to ~igure 3, at the circumferential
end of each arcuate part 30a, 30b adjacent the hinge arrange-
ment 30, the portion 32 i~ extended beyond the adjacent
circumferential ends of the flanges 34, 36 and i~ bent at
its end to form, with the correspondingly bent end of the
portion 32 of the other arcuate part and a hinge pin 42,
the hinge arrangement 40. The hinge arrangement 40 allows
the clamping ring to be opened to allow it to be slipped
over an assembled pipe joint and thereafter closed about
the joint. The manner in which the clamping ring ls held
clo~ed about the pipe ~oint is illustrated in ~igures 3 and
4. At the circumferential end of each arcuate part 30a,
30b remote from the hinge arrangement 40, the respective
portion 32 is extended beyond the adjacent circumferential
ends of the respect1ve flanges 34, 36 and the extended
portion l~ bent outwardly in a rever~e sen~ to the curva-
ture of the respective arcuate part; to provlde a generally
channel shaped formati~n 44 running generally parallel with
the axis of curvature of the respective portion 32, the wall
46 of each channel formation 44 which is furthest from the
hinge arrangement 40 terminating. in a respective free edge
48. The edges 48 of the walls 46 of the two arcuate part~
are so formed that when the clamping ring is in its closed
520
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position, with the relative positions of the parts 30a,
30b being as shown in Figure 3, the free edges 48, as
viewed in the direction of the arrow 50 in ~igure 3 are
inclined equally but in opposite sense3, with respect to
the direction of the axe~ of curvature of the respective
arcuate part 30a, 30b. Thus, in the closed position of
the clamping ring illustrated in Figure 3 the edges 48
slope t~wards each other from one axizl 0nd of the clamp
to the other, as viewed in the direction of arrow 50 in
Figure 3.
The clamping ring is held clamped circumferentially
around the joint by means of a generally channel-section
member 52, the member 52 having a flat wall 53 forming the
base of the channel and side walls 54 which, as ~iewed in
cross section in Figure 3, are curved so a~ t~ extend towards
each other at their free ends so that the channel is narrower
at its mouth than at the position intermediate its mouth
and its base. Each side wall 54 i8 of substantially uniform
cross section from one end of the member 52 to the other but
the width of the base 53 of the channel tapers fr~m one end
of the member 52 to the other and the directions of longitud-
inal extension of the two side walls 54 are correspondingly
inclined with respect to each other in the longitudinal
direction of the channel as shown in Figure 4, the mutual
inclination of the directions of longitudinal extension of
the side walls corresponding to the mutual inclination of
the edges 48 in the closed position of the clamping ring.
When the clamping ring has been closed about a pipe
joint, the wedging member 52 is slid over the flanges 46
in a longitudinal direction parallel with the axis of the
~oint, the widest part of the channel provlded by member 52
being engaged over the flanges 46 at the axial end where the
free edges 48 of these are closest and the member 5Z thereupon
slid in the axial direction, the edges ~8 bearing against the
inner surfaces of the side walls 54 and thereby being wedged
towards each other as the clamping member is slid along,
the clamping member being retained by the inwardly turned
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f`ree edge parts of the side walls 54 engaging in the channels
provided by the formations 44.
In the joint of Figure 1, the conically ~loping flanks
of the deformations 15, 17 and the corresponding flanges
34, 36 are inclined at 45 with respect to the axis of the
pipe joint. A pipe joint of Figure 2 corresponds in ~tructure
to that of Figure 1 except that, in the joint of ~igure 2,
the flanks of the deformations 15, 17 and ths correspondingly
inclined flanges 34, 36 are inclined at 30 with respect
to the axis of the pipe joint.
It will be not~d from Figure 1 that any internal fluid
pressure within a pipe system incorporating the joint of
Figure 1 or Figure 4 will tend to urge apart the lips of
the sealing member 28 providing the respective limbs of the
U-section, and will also tend to urge the seal into a
narrowing part of the annular space accommodating the member
28, said narrowing part being defined between the inclined
wall 22 and the exterior of portion 14. The seal i8 thus
urged more firmly into contact with the surfaces with which
it i~ intended to make sealing engagement, thus ensuring
good sealing.
It will be appreciated that, although an internal
pressure wlthin a pipe system incorporating the joint shown
in Figure 1 or Figure 2 will produce a force tending to
~eparate the pipes 10 and 12 axially~i such a force will be
counteracted, as explained previously, by the clamping
ring 30.
Furthermore, the axial length of the surface~ of end
portions 14 and 16 which are in mutual engagement in the
assembled pipe joint is sufficient to afford a high degree
of rigidity to the ~oint to withstand transverse bending
stresses. The axial length of *he last-mentioned surfaces
also affords self alignment of the pipes 10 and 12 in the
joint~
In addition~ the joint described ha~ the advantage of
being readlly assembled and just as readily disassembled
without damage to any of the parts of the joint.
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It should be appreciated that the above description,
with reference to the drawings, of pipe ~oints embodying
the invention ls given by way of non-limitative e~mple
only, and that this applies particularly to the clamplng
ring construction described wlth reference to Figures 3 a~d
4. The clamping ring may take any of a variety of other
possible forms consistent with its function, particularly
as regard~ the provision made for opening the ring ~ufficient-
ly to position it over the pipe ~oint and the means employed
for tensioning the ring circumferentially. However, the
general ~ectional shape of the clamping ring illustrated
in Figures 1 and 2 iB preferred for pipe ~oints having the
form illu9 trated in those figures.