Note: Descriptions are shown in the official language in which they were submitted.
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This invention is an improvement of Unitea States Patent
~o. 4,019,550 issued April 26, 1977 to De~Iaitre.
The invention herein is concerned generally with sealing
nuts and more particularly with a sealing nut having the ability
to withstand extremely high pressures. -
The particular environment in which the nut of the
invention is intended for use is one which poses stringent
re~uirements. The environment comprises a hydraulic chamber
which is subject to internal pressures above 20,000 p~s.i.
having a threaded stud or other threaded member extending
through a threaded passageway in the wall of the chamber, it
being desired from time to time to rotate the threaded stud for
reasons which are of no concern to this invention. Hydraulic
fluid deteriorates many substances; the environment may be ;~
subject to heat which may reach over 90C; the nut may have to
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be loosened and tightened often; the pressure may have to be
contained over a considerable length of time. There are other
considerations related to the general need for a locking and
sealing nut of this kind.
The sealing nut of the invention has a wide range of
utility in other environments as well as the particular one
,~ which is mentioned above, this being in connection with hyaraulic
brake systems for highway vehicles.
As will be explained, the insert of the nut of the invention~ 25 is formed independently of the nut body and before the nut body
is tapped. It is formed of a type of nylon which has a lubricant
~hat is compounded in it primarily for the purpose of enabling
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it to release readily from molds. Coincidentally, the
lubricating qualities assist in the taking up of the nut during
its last stages of installation. Such a material cannot be
molded and bonded into a recess as proposed by the prior art
because it will fall out. certainly if attempted to be secured
by some expensive means such as adhesive it cannot help but be
displaced during the tapping process.
To have a substantial protruding part and still secure
the insert mechanically~ into the nut body while at the same
time providing a space for the displacement of the protruding
;; part during installation is not taught by the prior art so
far as known. The displacement is a substantial one in order
to effect the seal and lock and the way of doing this with a
stiff insert material and without raising other probleMs is
-also not taught in said prior art.
~ The structures of the prior art which involve the use
of confined inserts have not displaced one of the principal
methods of assuring a seal in the high pressure hydraulic field.
The method in common use at this tima involves forming a recessed
seat in the surface of the body through which the male threaded
member is to be screwed, surrounding and coaxially wi-th the
threaded member. An o-ring or other sealing member to be conEined
is installed in the recess and adapted to be compressed by the
nut, either with or wlthout a washer. Several such 0-rings may
be used. This type of structure is expensive and the 0-rings
must be replaced frequently.
The invention herein is ideally suited for use in the high
`; pressure hydraulic field, but its principles are applicable in
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other fields where the requirements to achieve sealing are .--
not as great. This is because of the great economy and effec-
tiveness. This is true aside from the fact that it eliminates ~;:
the need for surface recesses, washers and O-rings~
S The most important difference between the sealing nut of
the invention and the prior structures is that the substantial :
protrusion of the insert (called a "crown") herein is not
intended to be only extruded and/or compressed during the take-
up action of the nut, as in the prior art, but instead is .
folded outwardly upon itself initiallyO Thus, a substantial
displacement is achieved without the need for expenditure of
large amounts of energy, meaning that great torques need not b~ ;
applied.in the early stages.of assembly. The crown is made
relatively narrow, i.e., measured radially, so that there is
enough space to enable the formation of a shoulder to provide .
. for securement of the insert into a socket by coining a lip
onto the shoulder while still leaving space (called a "gallery")
. for t-he folded end of the crown to seat. After this has occurred
and the axial end of the lip approaches the metal-to-metal con-
tact desired, the body of the insert is compact ready to receive
.~ the pressure for causing the necessary cold flow to effect
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sealing.- At this time, the maximum of torque is applied.
.. ~ The manufacture of the nut is highly economical since the
inserts are molded independently in production, the nut bodies
formed i.n a manner not differing substantially from that used
to make the bodies of elastic stop nuts, the inserts installed
in the sockets, the lips coined and the nuts tappedO The folded
crown is preformed prior to the nut being tapped by deflecting
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the crown outwardly.
As s-tated above, the nut~of the invention is especially
intended for use in the high pressure hydraulic field but its
principles are also applicable in circumstances where the
requirements are less stringent This should not be considered
to detract from the many features and advantages which are
achieved specifically in the high pressure hydraulic field.
In order to indicate the benefits and advantages of the
nut of the invention when used in the high pressure hydraulic
field there follows a list of the features achieved through
the practice of the in~ention in that field. In considering
this list, it will be apparent that the nut of the invention
is also applicable where insteaa of a so-called "wet" en~iron-
ment existing on the interior of a chamber through the wall of
which a threaded male member is adapted to be screwed, the
; environment may be "dry" but under gaseous pressure. Unless the
gas is corrosive, the problem of the deterioration of the insert
caused by hydraulic fluids and the like is eliminated.
The features which are set forth are the principal ones,
there being many others of a minor and indirect nature (not
necessarily in the order of importance):
(1~ The sealing material is rugged, stiff, durable
;. and yet has a sufficient degree of flow to
achie~e the necessary sealing and loc~ing.
i 25 (2) There is a substantial displa^ement of the
crown of the insert without requiring undue
torque and without damaging the insert during
such displacement.
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(3~ The insert is permanently locked lnto the body
of the nut, this being accomplished by machinery
and methods used to form elastic stop nuts of
conventional construction.
(4) There is a space (gallery) into which the dis- -
placed portion of the crown enters towards the
end of the take-up action.
(5) There is a metal-to-metal contact of the nut
body against the bearing surface after tha nut
has been fully ta~ken up at which time the insert
material is fully confined and has been forced
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, to flow into the areas where the sealing must
be effected.
(6) The nut and its insert are tapped with a
continuous thread during manuacture so that
the nut can be spun on the male threaded member
to the point where the actual taking up can be ~ -
commenced.
(7) The nut is reusable in that notwithstanding it
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; 20 has been tor~ued home and has effected a seal
and a locking, it can be unscrewed readily, is
;~ readily backed off without the need for application
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, of any substantial torque and can thereafter be
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reinstalled with as much sealing and lockiny
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, 25 efficiency as before.
; (8) The seal is such as to withstand extremely high
` pressures without leakage.
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(9) The nut has an indefinite shelf life since the
insert material does no-t deteriorate. This also
means that when installed and maintained under
pressure for a long period o~ time there is no,
relaxation which could give rise to leakage
because, in addition to the nature of the
material of the insert, it is confined and not
readily capable of cold flowing past the limits
- established by the act of compression in
achieving the metal-to-metal contact.
It should again be emphasized that the economy with
which the nut of tha invention can be made and its ef~activaness
make it well suited to form other applications in addition to
sealing in the high pressure hydraulic field.
lS The disadvantages of tha previous proposals may be ovarcoma
by providing a shouldered insert with a protruding crown locked
, into the nut body by a coined lip. Tha insert is tapped with ~''"
'~ tha nut body to form an integral threadad insert and nut.
In utilizing the nut the crown is outwardly folded into an '
, annular gallery between the inner edge of the coined lip and
,' the crown in a turtle-neck-like fold as it is moved against
, . the bearing surface. The bearing surface generally has a
chamfer into which the crown may be extruded to remove part of~
; the fold and locking the nut and insert firmly in place to make
reuse of the nut very difficult. ~he crown is angled or daflected
outwardly prior to utilizing the nut to partially prefold the
crown to enhance the reusa~ility of the nut. The crown is
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angled outwardly such that it does not receive a vertical
loading forcing it into the chamfer, but insteaa is folded
outward before cold flow can take place so that the fold is
not cut off in utilizing the nut.
S The preferred embodiments of this invention will now .
be described, by way of example, with reference to the drawings
accompanying the specification in which:
Figure 1 is a side elevational ~iew of a locking and
sealing nut constructed without the preformed fold of the crown,
.; 10 half of the nut being shown in section and the nut being shown
. in the condition it has before it has been put into use;
Figure 2 is a plan vlew of -the nut of Figure 1 taken
. from the bottom or insert end thereof;
`; Figure 3 is a fragmentary sectional view of the nut of
1~ the invention with portions shown in elevation, in the process
of being installed into engagement with the ~earing surface
of a metal body containing pressuri~ed fluid, the nut having
been partway screwed onto a threaded male member: -
, Figure 4 is a view similar to that of Figure 3 but sh~wing
. 20 the nut of the invention fully screwed home and sealing the
. joint represented by the male threaded member and the metal
body;
Figure 5 is a fragmentary sectional view o~ the nut of
the invention but showing the same some time after it has been
removed from a joint such as that of Figure 4;
Figure 6 is a side elevational view of the nut prior to
the de1ection or angling operation to preform the turtle-neck-
like fold;
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1092~1~
Figure 7 is a view similar to Figure 6 following the
deflection operation; and
Figure 8 is a view similar to Figure 7 of the preformed
turtle-neck-like fold after the nut ana insert have been
tapped.
Basically the invention is concerned with a sealing and
locking nut having an insert of a relatively stiff nylon in
which the insert protrudes and folds over upon itself when
the nut is engaged against a bearing surface. This gives rise
to the several advantages which have been described and enable
the nut to be made in an economical way with a structure that
provides highly efficient sealing and locking. The fold is
partially preformed to enhance the reusability of the nut.
The nut without the preformed fold is designated 10 and
shown in Figures 1 and 2 in its condition prior to use, after
it has been fabricated. In the fabrication techniques are used
which have been known in and of themselves and thus machinery
is available for such economical manufacture. The nut comprises
a nut body 12 having conventional hexagonal facets 14 to enable
its being engaged by a suitable spanner or wrench. There is
a central threaded bore 16 whose metal threads are shown at 18
in the upper part of the nut 10 as viewed in Figure 1. The nut
10 is formed with an annular interior socket 20 defined by an
annular, integral, generally axially extending wall 22 on the
bottom end of the nut body 12 and a conically tapered surface 24.
The recess 20 is drilled out during the fabrication o~ the nut
body 12. The outer diameter of the wall 22 is at most slightly
less than the diameter across opposite flat facets.
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In the recess there is provided an insert 26 in the form
of a ring of generally irregular cross section, the insert
being molded independently of the nut body 12 and initially
formed with a shoulder 28 lying in a plane normal to the axis
of the nut 10. For convenience the axis is shown by a broken
line and is designated 30. The insert 26 has an annular
protrusion at its lower end which is called a crown 32 and
extends axially beyond the wall 22 and hence protrudes
substantially from the lower end of the nut 10. The axial end
of the wall 22 is in the form of a hooked lip 34 that engages
against the a~ial end of the shoulder 28 and thereby forms a
gallery 36 between the crown 32 and said lip 34. The crown end
is roundea as shown at 33.
The upper end of the bore 16 is slightly countersunk at
` 15 38 and the outer corners of the nut are chamfered as at 40 in
accordance with conventional design practices~
The insert 26 is permanently locked in place by the wall 22 ~'
and the lip 3~ and its bore 42 is threaded as at 44 with the - '
identical thread 18. This is accomplished by assembling the
nut body 12 and the insert 26 with the bores 16 and ~2 unthreaded
and thereafter tapping both bores in a single operation.
'~ In,,~the manufacture of the nut 10 the body 12 is made on
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conventional screw machine apparatus independently of the insert
26. The outer circumference of the insert and the inner
circumference of the wall 22 at this time are of right cylindrical
~ configuration. The wall is longer than shown since the lip 34
,- is not yet formed. The dimensions are such that the insert 26
: is readily telescoped into the recess 20 in an easy slide fit.
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After this preliminary assembly, the nut 10 is placed in a
suitable press and the free end of the wall 22 is coined over
and upon the shoulder 28. In this process the wall 22 is
constricted somewhat and thus applies internal pressure against
the insert. It then assumes the generally slight tapered
configuration which it has in the drawings.
The insert 26 is made of a relatively stiff, high durometer
nylon. The material which has been used for the specific
application to the high pressure hydraulic field is described
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; 10 as heat stabilized-lubricated 66 nylon. This material is sold --
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` comrnercially under the trademark "Zytel 103 HSlL" by E. I.
Du Pont de ~emours. The lubricant may be a silicone, but in
any event it assists in the removal of the molded parts from
their molas and assists in the easing ofi friction during
installation and removal of the nut. It is heat retardant to a
temperature of about 105C. Its stiffness and memory make it
ideally suited for the purpose of the invention.
In the course of use of the nut 10 without the preformed
fold, the crown is outwardly inverted upon itself in a turtle-
neck-like fold which is then packed down into the gallery 36.
Pressure upon the insert thereafter effects the sealing and
locking function.
In Figure 3, the nut 10 has been engaged upon a threaded
stud or bolt 46 which in turn is engaged in a threaded
; 25 passageway 48 of a body 50 designed to contain some fluid 52
; such as hydraulic fluid at high pressure. The stud 46 might
` be any form of adjusting member, rnechanism operating device or
even a fastener which is required to enter the interior o the
--10--
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body 50 which requires that none of the fluid 52 escapes past
the stud 46 through the passageway 48. Likewise, it is desired
to lock the stud 46 from rotating or vibrating loose.
It is intended that the nut lO be screwed home against the
bearing surface 54 of the body 40 in such a manner as to seal
and lock the ~oint represented by the stud ~6 and the body 50.
Since the threads 18 and 44 have been cut at the same time to
the proper dimensions and clearance to fit the thread of the
stud 46, when the nut lO is first engaged on the stud 46, it
lO - will spin freely along the stud to the point where the free
end of the crown 32 just touches the bearing surface 54.
~It is presumed that the bearing surface 54 is metal such as
steel and that the body 12 of the nut is also steel.)
The next step in the procedure of tightening the nut is
to apply a wrench or spanner to the facets 14 and turn the nut
clockwise (looking down onto the surface 54 for a right-hand
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threa~). The first thing that happens is that the crown 32
starts to spread radially outward as it is forced against the
bearing surface 54. This is assisted by the rounded end 33
sliding on the surface 54. This condition about half-way through
the tightening process is shown at 32-A in Figure 3. The inner
- surface of the crown 32 must expand slightly in order for this
to occur and the crown 32 must be capable of bending. This must
be done without any breakage for example along the roots of
' 25 the threads 44 in the vicinity of the crown 32.
The 66 nylon which is used is fully capable of accomplishing
this. The dimension at X in Figure l being relat1vely narrow
compared to the overall diameter and the axial length of the
" -11
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crown proviaes sufficient flexibili-ty For example, in a nu-t
having a 5/8 inch tapped thread of 18 threads per inch, the
outer diameter of the crown was about .78 inch and the amount
protruding axially beyond the lip 34 was about .085 inch.
This particular nut was one which used a so-called heavy
pattern, the dimension across the flats of the facets 14 being
about 1.05 inch.
Continuing with the explanation of the inversion of ;~
the crown 32, the torque which is required to start this
inversion is relatively less than the final torque which will
be applied. It is less than that which would be required to
crush the insert and thereby force it to flow into interstices
where it might be desired. The application of torque is con-
tinued until the crown 32 is fully pressed into the gallery 36
as shown at 32B in Figure 4. ~ust before the end of the lip 34
engages the surface 54, the complete fold has taken place and
the line of fold is shown at 56. This has been referred to as
a turtle-neck-like fold. It results from an inversion of about
90 for the crown 32, which while it is not a complete reverse
fold is nevertheless quite substantial for a synthetic resinous
material and unique, so far as known, for any type of nut insert.
The volume of the crown 32 that will be pressed into the
gallery 36 is chosen, easily by trial and error, to be more than
enough to fill the gallery before the free end of the lip 34
engages the bearing surface 54. This means that as the last
turn or turns of the wrench are being applied, the body of the
insert 26 has tremendous pressure applied to it tending to ma~e
it expand. Through cold flow, the material of the insert 26 is
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forced into the threads of the stud 46 in the area 58; into -the
clearance space between the threads 18 and the threads of the
stud 46 in the area 60; and also into the countersink 62 that
is formed in the entrance of the passageway 48. This effects
both a sealing and a locking of the stud 46 in place.
In a joint such as described, using a 5/8 x 18 sealing nut
; of the dimensions mentioned above, that is, with the heavy
design of the nut body 12, withstood over 50,000 p.s.i. in a
test of hydraulic equipment without failure or leakage.
The nut 10' is reusable, as explained. Thus, if the stud
46 has to be turned temporarily, the nut lO'ma~ be backed off
;~ until the insert is relieved of pressure after which the stud
` may be rotated and the nut lO're-torqued to seal and lock with
substantially the -same effectiveness as before. It has been
15 found that after the nut has been in place and under pressure
for a period of time it generally can be completely removed
from the joint and later reused. The configuration of the
insert is changed, but not to a degree that renders the nut
useless. Due to the remarkable "rnemory" of polyamide resin,
the crown 32 will slowly tend to return towards its original
configuration, although it may never reach the same.
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In Figure 5 there is shown a nut lO'which has the
- configuration of a crown at 32C which had been compressed to
its folded condition and subjected to very substantial pressures
for a period of time. It will be noted that the fold 56 has now
opened up and can be seen at 56A and that there is an annular
protrusion at 62A. This represents the poxtion of the insert
that was forced into tha countersink 62.
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The nut l~' gener~lly can be reused effectively on the
same jolnt from which it was removed. -
In Figures 6-8 there is shown a nut 10" which is formed
with a preformed turtle-neck-like fold on a crown 32' of an
S insert 26'. It has been discovered that the reusability of
the nut 10' as shown in Figure 5 may be effected by the ~ -
protrusion shown at 62A. As previously stated this represents .
the portion o the insert that was forced into the counter~ink
or chamfer 62 and into the threads of the stud 46 locking both,
~ which is undesirabl.e in a calibration or reusability situation.
,
The resulting protrusion 62A does not cause a significant
problem if the nut 10' is not to be reused, or the bearing
: . surface 54 is unchamfered.
~ problem may exist due to a large size o~ nut, due to
the pressure the insert is under or due to the conflnement
. of the insert (or a combination of all three). Part of the ~ .
: insert, especially a portion of the protrusion 62A, may be .
~ cut off or may be jammed into the threads of the stud 46 in
; the area of the chamf~r 62 such that it can be difficult to
. 20 calibrate the mal.e stud and/or remove the nut. Furthermore,
:~ . when any portion of the protrusion 62A is cut off, the high
~ pressure sealing capability of the nut is affected when the
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nut i5 reusedO To overcome these problems the nut 10" is
formed with the turtle-neck~like fold of the crown 32' partially
preformed. This provides several advantages including no loss
of material from the insert 26' because the protrusion 62A will
not be extruded into the chamfer 62, the nut 10" has an increased
life, and the installation torque required for seating the nut
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lO"is reduced The sealing of the nut is not e:~fected, but
the performance is improved.
As shown in Figure 6 the nut lO" is formed in the same
manner as the nut lO previously described, with the wall 22
engaged against the axial end o:E the shoulder 28 of the insert
` 26' which includes the upstanding crown 32'. The manufacturing
steps to form and to lock the nut body 12 and insert 26'
together are identical to those previdusly discussed; however,
at this point one additional step is performed to preform the
turtle-neck-like fold of~ the crown 32' before the nut 10" is
tapped. A deflection tool 70 is pressed downwardly against the
top o the nut 10" deflecting or bumping the crown 32' in a ~:
radially outwardly direction to partially preform the turtle-
neck-like fold. The deflection tool 70 may bé mounted in a
:, 15 conventional punch press or other conventional machinery to .
press the deflection tool into the untapped bore 72 of the
.` insert 26'. Although it is preferable to utilize the deflection
tool 70, it would be possible to mold the insert 26' with the
crown 32' partially folded over as shown in Figure 7.
As shown in Figure 7 the crown 32' has been deflected or
bumped radially outward to partially form the fold as shown at .
74. The insert 26' is still made of a relatively stiff, high
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. durometer 66 type nylon. These nylon resins are sold under
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the trademark "ZYTE~" by E. I. DuPont de Nemours. The 66 nylon
25 is one of the four basic groups of the "ZYTEL" nylon resins.
As previously stated these nylon or polyamide resins have a
"memory" which will tend to draw the folded over crown 32' back
toward its original position as shown in Figure 6, but the crown
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32' will remain partially folded over as shown at 74.
Typically, the crown 32' will be folded to pxeform appro~imately .
50 percent (50%) of the turtle-neck-like fold which is completed
and compressed when the nut 10" is fully screwed down a~ainst
a metal surface completely enclosing the crown 32' in` the
gallery 36 defined by the shoulder 28, the metal body bearing
surface 54 (Figure 4) and the edge of the wall 22 When the
nut 10" is used and fully torqued down the gallery 36 will
substantially be filled as beore; however, no insert material
will have been extruded into the chamfer 62 and the threads o~
the stu~.
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The deflection tool 70 has a radially increasing rounded
surface 76. The smaller radius on the end 78 of the deflection
, tool 70 must have a radius su~stantially equal to or sli~htly
smaller than the bore 72. An upper surface 80 is provided
with a radius which is chosen so that the crown 32' will be
deflectea or bumped radially outward to a distance greater than
the outer radius of a standard countersink or chamfer 62 on the
surface 54 of the metal body 50. Once the deflection tool has
; 20 been pressed into the bore 72 and removed as shown in Figure 7
the nut 10" will then be tapped to form the continuous thread ~ :82 in both the insert 26' and the nut body 12 as before The
. crown 32' does not return to its original position but remains
folded as shown at 74 so that the threads 82 are not ~ully formed
. in the upper portion of the insert at 74. Thus, the insert 26'
of the nut 10" has a preformed turtle-neck-like fold which
enhances the utilization of the nut 10" as previously discussed
and allows the nut 10" to be reused without a decrease inper~ormance.
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