Note: Descriptions are shown in the official language in which they were submitted.
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This ap~lication rela~es generally to tlle field of clamps for
clamping of tubular sections. ~ore particularl~, the invention relates -to a
band seal clamp wherein a generally c~lindrical straplike band is clamped
around two portions of pipe o$ generall~ circular cross-sectlon, which may be
either butted against one another or be sized so that one fits wi-thin the
other. Upon tighkening of the clamp a rigid and mechanically strong connection
is formed which exerts a radially inward, subtantially uniform force completely
aro~lnd the circumference of the tubes.
The prior art is replete with various attempts at solving the
problem of clamping two generally cylindrical members, for example tubes or
pipes, together. The problem is to provide a clamp which exerts a radially
inward force uniformly around the entire circumference of the tubes to be
fastened together. ~hile it is relatively straightfor~ard to exert the force
over the greater portion of the circumference of the tubes, it is important if
a mechanically strong and leak-free connection is to be formed that the force
be exerted over the entire circumference of the pipe. To this end, numerous
attempts have been made in the prior art to provide rigid pipe couplings; see,
far example, United States Patent 494,996 to Dwelle in ~hich rigid hinged
members are clamped together to grip the pipe. See also United States Patent
2,227,551 to ~orris which shows clamps having interlocking fingers to be
clamped together to exert the force QVer the entire circumference of the tube.
Later ~atentees realized that it would be preerable to use a somewhat flexible
band wh~ch would be slightly deformed ~o more closel~ match the contaurs of
the pipe to be clamped, thus being more likely to exert the orce uniforml~
araund the entire circumference of the pipe. Into this class fall the patents
tQ Cassel et al United States 4,056,273 and United States 3,9Q5,623, as well as
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that to ~oti United States 4,165,109. All these show provision of cla~ps which
use a plurality of bolts connecting two ends of a band wrapped around a pair of
pipes to be joined and havlng a connection piece i.nterposed therebetween.
Typicall~, the connection piece ls formed wich an axially extending recess
formed between the bolt ho].es on both its sides so that upon tightening of the
bolts the ends of the band will be deforlned to fit more closely together within
the recesses; force bars may be used to spread the orce exerted by tightening
the bolts uniformly across the wldth of the clampO In some cases, particularly
United States Patent 4,056,273 to Cassel, the shaping member may also be shaped
to coact with the outer circumference of the tube so as to exert a radially
lnward force thereon by being pulled into the surface of the pipe by the
tightening of the bolt~s) simultaneously with deormation of the ends of the
band. However, the fact th,at this deformation is required means that the
orce exerted upon tightening the bolts is at least partiall~ directed towards
this deformation ancl is not useful in achieving the primary object o~ the
clamp, that is, to e:xert a generally radiall~ inw.ard force substantially
uniformly around the circumference of the tubeO
As ~ill be discussed in further detail below, the present invention
is directed at solving this need of the art in that it has as its primar~
ob~ective the provision of an improved band seal clamp for the clamping of
tubes together.
The improved band seal cla~p should preferahly provide a substant-
ially uniform clamping force exerted radially inwardly about subs~an*ially
the entire circumference of the tube, Substantial deformation of the ends of
the band is to be avoided upon tightening of the clamp. The band seal clamp
can be readily assembled in a "band aid" mode, that is~ ~ithou~ disassembly of
pairs of tubes to be clamped; instead, the clamp can be slipped around the tubes
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without their disassembly or without requiring free access from
the joint to be clampec~ to one end of the tube.
Summary of the Invention
The inventlon provides a band clamp for clamping of one
or more tubular memberc;, comprising: an elongated flat strip oE
material adapted to be circumferentially wrapped around said tubu-
lar members to be coup].ed and having outwardly extending end por-
tions, said end portions having slots extending in the direction
of elongation of said strip for interaction with clamping means
inserted therethrough; a central shaping and spacing member adapted
to be disposed between the end portions of said strip and having
holes formed therein for insertion of said clamping means, said
holes being so sized as to fit relatively closely with said clamp-
ing means, and shaped t:o fit said tubular members to be clamped;
and first and second fc,rce transmitting members adapted to be dis-
posed on opposite sidec of said centxal shaping member and of said
end portions of said ba~nd, said force transmitting members having
holes formed therein fc,r insertion of said clamping means and hav-
: ing outwardly extending reaction surfaces formed thereon to inter-
act with inwardly exten.ding reaction surfaces formed on the end
portions of said band, whereby the slots permit the end portions
of said band -to move generally radially outwardly with respect to
said tubular members when clamped by said clamping means.
The invention also provides a band seal clamp for clamp-
ing one or more tubular members, comprising: a spacing member hav-
ing one or more holes formed therein for the inser-tion of generally
cylindrical bolts and adapted to space the axes of said bolts a
predetermined distance from said tubular members; at least one
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force har having holes ormed therein for the inse:rtion of said
bolts, and having a generally planar surface extending generally
axially with respect to said -tubular members and disposed at an
angle between about 30'' and about 60 with respect to a plane on a
diameter of said tuhular members passing through the center of said
spacing member; and a generally strap-like band having Eirst and
second end portions having slots formed therein for insertion of
said bolts, at least one of said end portions being shaped so as to
coact with said surface formed on said force bar, so that upon
assembly of said band i.ts end portions are disposed on opposite
sides of said spacing member, said force bar is disposed on the
same side of said shaped end portion of said bands from said spac-
ing member, said shapecl end portion separating said force bar from
said spacing member, and said bolts are inserted through said holes
in said spacing member, through said force bar and through said
slots in said band, such that upon tightening of said bolts, the
slots permit the end portions of said band to move in a direction
generally radially outwardly from said tubular member, whereby a
substantially uniform compressive force is exerted at all points
around the circumference of said tubular members covered by said
band.
The invention will be better understood if reference is
made to the accompanying drawings, in which:
Figure 1 represents an overall perspective view of a
exemplary preferred embodiment of a complete connector according
to the invention;
Figures 2a-2c represent cross-sectional views of
successive stages in the clamping of a tube by the coupling of the
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invention, taken along the line 2c-2c of Figure l; and
Flgures 3a-3c represent comparable cross-sections of a
second embodiment of the invention shown at various stages of
assembly.
As described above, this invention re:Lates to the pro-
vlsion of a
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band seal clamp for clamping two tubcs togetherO A completed assembly of such
a clamp according to the invention is depicted generally in Figure 1 clamping
two tubes shown in phantom. The two ~ubes may be butted together or one may
slide within the otherO In either case, the objective of the clamp is to
exert a substantially uniform compressional force directed radially inwardly
on the tubes~ This is done by tightening two bolts 12 which cause the band 10
to tighten generally upon the tubes. The bolts 12 operating in concert with
shaped members or force bars 14 cause the overall circumference of the band 10
which is in contact with the tubes to decreasel thus exerting a compressional
10 force on the tubeO This movement is effected by the relative shaping of the
force bars 14 with respect to a central shaping member 16 in a manner which
will be discussed more fully belowO
Referring now to ~igures 2a through 2c, the sequence of operations
leading to clamping of *he tubes by the clamp of the invention is shown. In
Figure 2a, a portion of a tube 20 and a section of the band seal clamp 10 of
the invention are shown. As wilL be apparentJ the first step in assembly of
the clamp is to bring the two ends 22 and 24 of the band together. These ends
have down-turned portions 22a and 24a respectively which fit within a groove
26 formed wi~hin the central shaping and spacing member 16. They are retained
20 there by the "spring" of thl3 band, typically formed of formable steel. As
noted, the central shaping and spacing member 16 comprises an upper portion 16a
and a lower portion 16b which are connected by a thin tongue of material 16c;
one or more holes indicated by dotted lines at 16d are formed in the spacing
member 16 for insertion of through bolts 12 (Figure 2b). These holes 16d are
shaped to fit bolts 12 relatively closely, as compared with the corresponding
holes formed in the band 10 which are instead slotted, to permit movement of
the band 10 with respect to
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the bolts 12 for reasons l~lich will be discussed below.
Referring now to ~'igure 2b, the bolts 12 are shown assembled toget-
her ~th the force bars 1~ disposed on either side of the shaping member 16.
A nut 28 is used on the opposite side of the bolt 12 from its head; however,
it ~ill be understood that one o the orce bars 14 could b~ threadedl although
this would then mean that the~ could not be identical. Similarly, the force
bars could be individually fitted ~o the bolts. They could be circular in
outline, or elongated as sho~n. Whatever, the shape of these force trans-
mitting members, the bolt holes must fit the bolts well enough that the
reaction surfaces cannot be rotated out of contact with the band 10. The force
bars 1~ are formed to comprise a generall~ semi-circular cross-section which
ma~ have a substantially flat face shaped to interact with recesses formed in
the cross sectional outline o~ either side of the central shaping and spacing
nember 16 and with the band 10 fitting therewithin. As shown in Figure 2b,
the initial hole 16d formed for the insertion of the bolt 12 in the shaping
and spaclng member 16 is positioned so as that upon assembly of the force bars
14 their semi-circular outline shape does not fit within the semi-circular
recesses in the shaping member 16, but instead is disposed some dlstance
outwardly along a radial line with respect to the tube 20. The bolts are thus
~0 fixedl~ spaced c.ut~ardly from the tube 20 b~ the shaping member 16. Therefore,
upon tightening of the nut 28 ~ith respect to the bolt 12 an unbalanced force
~ill be exerted on the band 10 by the force bars; since the hole 16d in the
shaping mem~er 16 fits the bolt 12 closel~ as explalned above, the resultant
force exerted tends to separate the upper portion of the shaping member 16a
~rom the lower portion 16bu Since the ends 22 and 24 of the band are held b~
the shaping and spacing member 16~ the upward movement of the upper portion 16a
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with respect to the lower portion 16b o$ the shaping member tends to *ighten
the band 10 on the tube 20, Eventually the tongue 16c breaks$ which permits
further uplif~ing of the ends of the band; concomitantly, of course, the band
is tightened by the relative outwarcl movement of the rigidly fixed end sections
indicated generall~ at 22 and 24. A shaping rnember having such a frangible
tongue could be made by a process such as ex~rusion, or perhaps by molding.
~owder metallurgy techniques might also be employed.
As shown in Pigure 2c the net effect of tightening the bolts is to
move the upper portion 16a ~f the shaping member 16 outwardly with respect to
lQ the lower portion 16b; as the ends of the band 22 and 24 are attached to the
owter portion 16a, the band 10 is tightened about the tube 20 upon tigh~ening
of the nut 28 with respect to the bolt 12.
It will be appreciated by those skilled in the art that this method
of tightening the band prov:ldes a relatively limited range of adjustment, which
means merely that a given b~md seal clamp will only be use~ul to clamp tubes of
a relatively limited range of sizes. Since, however, tubing is manufaGtured
only to specific and well-known sizes, this poses no difficul~y but instead
provides the advantage of a]lowing the underside of the lower portion of the
shaping member 16 to be curved as at 16e so as to fit the tube 20 very closely.
In this ua~ the net force exerted on the tube is relatively uniform around its
circumference, being merel~ a function ~f the total force exerted by tightening
the nuts 28 on the bolts 12 divided by the area of the band 10 combined with
that of the curved surface 16e. By making the wldth of the band equal to the
length of the shaping member~ the force exerted ~ill be uniform all the way
around the circumference of the clampO
Figures 3a through 3c sho~a second preferred embodiment of the
invention. These three figures are all cross-sections taken through one of ~he
plurality of bolt holes ~oxmed in the band 10 and in the central spacing member
30 and show how the tightening of the bolt results in relative compression of
the tube by the band, ~or exaD~ple, in ~igure 3a the band 10 is shown generally
assembled about a central ~lember 30 having one or more holes 32 formed therein.
The hole 32 is sized so as to fit relatively closely with a bolt 34 (Figure 3b)
inserted therethrough, while a somewhat wider slot lOa is formed in the band
10. As noted from Figure 3a, the ends of the band 10 may be formed ~o comprise
surfaces lOf and making an angle--typically bet~een about 30 and about 60,
l~ith respect to a plane on a diameter of the tube and going through the center
af the spacing member 30--simply by folding over of its ends, and may thus
double the thickness of the band in ~he region of the holes lOa. As noted,
the hole lOa is a slot being larger than the hole 32 formed in the central
member, so that relative movement of the band with respect to the bolts 34 is
posslble~ Referring no~ ~o ~igure 3b, a bolt 34 is shown having been assembled
through the slQt lOa and through the hole 32 in the central spacing member 30.
~atching force bars 36 are dispased on opposite sides of the central spacing
member and are held in place by the bolt 34 on which is threaded a nut 38. As
discussed above, the ends of the band 10 are formed to comprise angled reaction
surfaces lOf disposed on either side and awa~ from the central shaping member
3~. These reaction surfaces lOf are adap~ed ~o interact with shaped surfaces
on the force bars 36 and are disposed with respect to the slot lQa so that
upon assembly of the force bars 36 together with bolt 34 and nut 38 the force
bars 36 will only touch the ends of the band 10 at the reaction surfaces lOf~
so that when the nut 38 is tightened on the bolt 34 thus exerting an axial
stress on the bolt, the force exerted on the band 10 by the force bars 36 will
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be exerted only on the shaping surfaces lOf. Since these surfaces are on the
side of the bolt 34 opposite the tube 30, the net effec~ of tightening the
bolt 34 will be to pull thls ends of the band 10 together and force them to
slide out~ardly past the force bars, thus tightening the band 10 on a tube or
pair of tubes about ~hich it is encircled. Clearl~, the interacting surfaces
of the band lOf ~nd of the force bars 36, as in the case o~ the embodiment
of Figures 1 and 2a-2c need not be simple planes or semicylindersl so long as
they form a tangent surface throughout their relative movement. It will
furthermore be understood that a plurality of bolts and nuts could be used by
axial extensions o the force bars and spacing members, widening the band, and
multiplying the holes and slots. Another possibilit~ would be to fill the
loop-like structure formed on the ends of the band with an incompressible
member such as a rod, to preclude c~llapsing of the loop~ though the passage
o the bolt 34 through the slots formed in both the bod~ of the band and in
the folded over loop end would largel~ eliminate this possibility.
Further t:ighteni~ng of the nut 38 upon the bolt 3~ results in ~he
condition shown in F:igure ;c, where the force bars 36 have bottomed in ~he
recesses formed in the end of the band 10 by its bending over to form its ends.
~t ~111 b~ noted that in this embodiment the ends of the band are shaped to
provide a reaction surface lOf to interact with the force bars, as opposed
t~ the embodiment of Figures 2a-2c, in which the central shaping and spacing
member provides the reactian surface. In the embodiment of Figures 3a-3c, the
function of member 30 is ch,iefl~ therefore spacing the bolts 34 from the sur-
~ace of the tube to be clamlped, and providing shaped surfaces 30a and 30b
tFigure 3~ to exert force uniforml~ on the tube and to provide a ~ide radius
bend to the band upon tightening of bolts 34 respectivel~. As noted, the shaft
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of the bolt 3~ no~ abuts the bottom of the slot lOa formed in the ends of the
band lO, as opposed to the position sho~n in ~igure 3b. ~rrows drawn in
Figure 3c show the movement o~ the various parts of the clamp according -to -tlle
invention, upon tightening of the nut 38 with respect to the bolt 3~.
As discussed abl~ve in connection with Figures 2a through 2c, the
amount of tightening provided by the clamp according to the invention is rel-
atively limited, which requires that the clamp be chosen to it relatively
closely upon the tube prior to assembly. In turn this results in the advantage
that the underside 30a of 1he central shaping member 30 can likewise be chosen
to fit the tube relativel~ accurately, whereby substantially uniform compres-
sional forces are exerted at all points around the circumference of the band
on the tube~
It will be appreciated that there has been described a band seal
clamp for the clamping of 1:ubes to one another which meets the needs of the
art and objects of the inve~ntion described above, although it might also be
useful in clamplng a single~ tube, e.g. to clamp a plug over a leak. ~he clamp
of the invention is simple and readily and inexpensively manufacturable~ yet
exerts a substantially unif`orm compressional force upon tubes clamped thereby.
Moreover, the fact that it relies upon relative movement of the band with
respect to the clamping bolts, the positions of whlch are fixed by the central
spacing member, as permitte~d by the formation of slots in the ends of the band,
rather than upon simple deformation of the band to fit a recess formed in a
central shaping member, as shown in the prior art, results in more of the total
f'orce being applied to cla~ing and less lost to deformation. Finally, it will
be appreciated that while two preferred embodiments of the invention have been
descrlbed, numerous other modi~ications and improvements are possible. In
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particular, the clamp of the invention need not be symmetric; only one en~ of
the band need have an angled reaction surface, and only one forcebar need be
providedO In some circumstances this might simplify manufacture and/or
assembly of the clamp of t:he invention. Therefore, the scope of -the inven-tion
should not be measured by the above disclosure) which :is exemplary only, but
rather by the following claims.
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