U.S. patent number 3,561,776 [Application Number 04/777,227] was granted by the patent office on 1971-02-09 for composite ring seal and method of making.
This patent grant is currently assigned to The Fluorocarbon Company. Invention is credited to John D. Wilson.
United States Patent |
3,561,776 |
Wilson |
February 9, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
COMPOSITE RING SEAL AND METHOD OF MAKING
Abstract
A radial loaded ring seal having an annular jacket of suitable
material such as Teflon, the jacket being of channel-shaped cross
section surrounding a loading spring of channel-shaped cross
section, the loading spring being fabricated from a spring strip of
suitable material such as stainless steel by being helically wound
into a tube in which the edge margins of the successive
convolutions are in overlapping relation, the tube then being
formed into a ring and deformed under suitable pressure means in a
die or by other suitable means into a generally U-shaped annular
spring member having a double-walled channel with a radial side
opening, after which the preformed jacket is applied to the spring
to provide a composite structure in which the jacket forms a shield
for the spring which in turn provides radial energizing means for
the jacket.
Inventors: |
Wilson; John D. (Pacific
Palisades, CA) |
Assignee: |
The Fluorocarbon Company
(Anaheim, CA)
|
Family
ID: |
25109648 |
Appl.
No.: |
04/777,227 |
Filed: |
November 20, 1968 |
Current U.S.
Class: |
277/647; 277/651;
277/946; 277/652 |
Current CPC
Class: |
F16J
15/121 (20130101); Y10S 277/946 (20130101) |
Current International
Class: |
F16J
15/12 (20060101); F16j 015/32 () |
Field of
Search: |
;277/152,153,205,206,212C,235 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Myhre; Charles J.
Claims
I claim:
1. A composite sealing ring, comprising:
a. an annular flexible sealing jacket of channel-shape in cross
section formed to provide spaced opposed side walls; and
b. circumferentially extending spring loading means between said
sidewalls, said spring means comprising a helically wound flat
strip and being of generally channel shape configuration in cross
section and formed to provide spaced opposed sidewalls respectively
acting on said jacket sidewalls to resist deformation thereof.
2. A sealing ring according to claim 1, wherein the wound strip
presents an imperforate substantially smooth surface.
3. A sealing ring according to claim 1, wherein the edge margins of
successive convolutions of the wound strip are in overlapping
relation.
4. A sealing ring according to claim 3, wherein the exposed
overlapped edge is of less thickness than the concealed edge.
5. A sealing ring according to claim 1, wherein the spring means
channel is substantially U-shaped and formed with a double
wall.
6. As an article of manufacture, annular spring means,
comprising:
a. a ring formed by a helically wound ribbonlike strip having
overlapped convolutions, said wound strip having its opposite ends
connected;
b. said ring having a double-walled U-shaped cross section
including an inner wall and an outer wall; and
c. with the portions of the convolutions in one of said walls being
oppositely inclined in relation to the portions of the convolutions
in the other of said walls.
7. An article of manufacture according to claim 6, wherein the ring
surface is imperforate.
8. The method of fabricating a composite sealing ring, which
comprises the steps of:
a. forming annular spring means of generally channel-shaped cross
section having a side opening and in which a helically wound
ribbonlike strip of spring material has marginally material
successive convolutions; and
b. thereafter conforming to the spring means a flexible sealing
material to provide a ring jacket having a channel-shaped cross
section with channel wall portions respectively embracing opposed
channel wall portions of the spring means.
9. The method according to claim 8, wherein the edge margins of
successive convolutions are wound into overlapping relation.
10. The method according to claim 9, wherein the spring means
presents a substantially smooth imperforate surface of engagement
to the jacket.
11. The method of fabricating a loading spring for a composite
sealing ring, which comprises the steps of:
a. helically winding a ribbonlike strip of spring material into a
tubular structure in which the edge margins of successive
convolutions are in overlapped relation;
b. forming an elongate portion of the tubular structure into a ring
configuration with the opposite ends of the portion juxtaposed;
and
c. thereafter deforming the ring wall to obtain a ring
configuration having a channel cross section.
12. The method according to claim 11, wherein the deformed ring
wall provides a substantially U-shaped channel.
13. The method according to claim 11, wherein the ring channel is
defined by a double wall.
14. The method according to claim 11, including the additional step
of bonding the strip ends together at the juxtaposed ends of said
portion.
15. The method according to claim 11, wherein the edge of the wound
strip which is outwardly exposed is of less thickness than the
other edge, whereby the tubular structure will have a substantially
smooth outer surface.
16. The method according to claim 11, wherein the ribbonlike strip
prior to winding is stretched along its leading edge to decrease
its thickness.
17. The method according to claim 16, wherein said leading edge is
stretched by feeding the strip edgewise, prior to winding, over an
arcuate path in which the leading edge is radially outwardly
positioned with respect to the other strip edge.
18. The method according to claim 11, wherein the ring wall is die
deformed to provide a double-walled circumferentially extending
U-shaped channel having a radial open side.
19. A sealing ring, comprising:
a. annular spring means of U-shaped transverse section including a
helically wound ribbonlike strip having overlapped convolutions
coacting to provide a doublewall in said section; and
b. a sealing medium overlying surfaces of the wound strip adapted
to sealingly engage a surface under the loading provided by said
spring means.
20. A composite sealing ring, comprising:
a. an annular flexible sealing jacket of channel-shape in cross
section formed to provide spaced opposed sidewalls;
b. circumferentially extending spring loading means between said
sidewalls, said spring means being of generally channel-shape
configuration in cross section and formed to provide spaced opposed
sidewalls respectively acting on said jacket sidewalls to resist
deformation thereof; and
c. said jacket sidewalls having inner and outer wall portions
embracing and shielding the spring means in an operative position
from the sealed medium.
21. A sealing ring according to claim 20, wherein the jacket outer
wall portions have circumferentially extending outer sealing
faces.
22. A sealing ring according to claim 20, wherein the spring means
has a substantially U-shaped cross section with sidewalls extending
from a bottom bridging portion, and the jacket sidewalls include
portions overlapping said bottom bridging portion on its inner and
outer surfaces.
23. A composite sealing ring, comprising:
a. an annular flexible sealing jacket of channel-shape in cross
section formed to provide spaced opposed sidewalls;
b. circumferentially extending spring loading means between said
sidewalls, said spring means being of generally channel shape
configuration in cross section and formed to provided spaced
opposed sidewalls respectively acting on said jacket sidewalls to
resist deformation thereof; and
c. said jacket channel being substantially W-shaped and the spring
means channel being substantially U-shaped, the jacket and spring
means being mounted with the open sides of said channels in
confronting relation, and the jacket wall portions embracing and
shielding the spring means in an operative position from the sealed
medium.
Description
BACKGROUND OF THE INVENTION
The present invention relates to ring seals.
Heretofore, it has been known that the characteristics of certain
plastic materials possess inherent properties which make them
particularly advantageous for use as a sealing material. One of
these is polytetrafluoroethylene resin, commonly known as "Teflon."
Principally among the desirable characteristics of this material
are its wide temperature range, chemical inertness, low friction,
unlimited shelf life, high tensile and compressive strength, high
wearability, and an ability of the material to seal by conforming
to other surfaces. A desirable property which this material lacks,
however, is that of elasticity, and for this reason it has not been
possible to utilize it directly as a substitute for rubber and
other elastomer types of seals where dependence upon natural
resiliency is necessary to supply sufficient force at the interface
of the seal and faying surface to effect sealing.
In order to overcome the lack of resiliency of Teflon, prior art
structures have been designed with a loading spring which is
arranged to artificially provide the resiliency which is lacking in
the Teflon material. Such structures have been utilized in axially
loaded seals, as well as in radially loaded seals. However,
primarily due to the structural design of the spring element, the
prior art devices have not been entirely successful for a wide
range of installation conditions.
More specifically, it may be noted that in the case of axially
loaded seals, one conventional construction has utilized a
perforated U-shaped annular spring while another has utilized a
V-shaped spring to energize a Teflon sealing surface. Seals of this
type have been used in connection with pipe flange joints, fuel
line connections, and similar installations. Use of either of these
spring structures for a radial loaded seal is not practically
possible as the stress characteristic is changed from essentially a
beam loading in the axial loaded seal to a circumferential loading
in a radial loaded seal. The spring operation is thus changed from
a low stress/deflection to a high stress/deflection.
In the case of radial loaded seals, the trend has been to endeavor
to design the loading spring so that it will embody a minimum of
perforations, gaps, irregularities, or discontinuities, as well as
high compliance (a low stress/deflection factor). Exemplary of
springs which have been used in the radial loaded seal designs of
the prior art is a helical wound, garter-type spring of wire or
flat strip material. However, such springs have openings or gaps
between the load applying surfaces engaged with the jacket. In
other known designs of the prior art, a wire wound helical spring
has been used. However, such a construction aggravates the
condition. In still another design, a U-shaped spring has been used
in which individual sections eliminate circumferential stresses,
but still leave gaps and irregularities in the application of load
to the jacket.
In the present invention, the inherent disadvantages of the prior
art structures have been overcome by a unique spring design which
eliminates openings and gaps and provides a relatively smooth
loading surface, while at the same time enabling the use of a
U-shaped section spring of generally conventional configuration but
offering high compliance when utilized in a radial loaded
orientation. Since the loading is substantially continuous, the
spring of the present invention permits a thinner jacket than is
possible in conventional designs. This is a vital advantage as in
many applications it avoids the possibility of a thick jacket
overpowering the spring under certain operating conditions which
could cause a failure of the seal.
The spring structure of the present invention provides a longer
jacket life in dynamic applications, and overcomes the
disadvantages of springs of the prior art structure under static
conditions where, for example, helical wound springs, particularly
those utilizing wire, have been known to cut through the jackets.
The spring structure of the present invention further permits the
fabrication of a radial loaded seal with a W cross section jacket
which is particularly advantageous to form a shield over the spring
as a protection against types of sealed media which would be
damaging to the spring material. Further, in pharmaceutical and
reagent chemical manufacturing, the jacket is "clean," easily
rinsed, and not a source of entrapment for fluid which may later
act as a contaminant. In the case of food processing, it is
apparent that media such as milk cannot be sealed in commercial
equipment with "open spring" seals, since this design does not
insure complete removal of entrapped milk, even with steam
cleaning.
SUMMARY OF THE INVENTION
The present invention relates generally to sealing rings and is
more particularly concerned with sealing rings of the type which
are radially spring loaded, and an improved method for the
fabrication thereof.
Having in mind the inherent disadvantages of the prior art
structures as previously explained, it is one object of the
herein-described invention to provide a spring-loaded ring seal
capable of utilizing a material such as Teflon and which will have
low stress/deflection characteristics.
A further object is to provide a composite ring seal in which an
annular sealing jacket is energized by a loading spring comprised
of an imperforate helically wound strip in which the marginal edges
of adjacent convolutions are in overlapping relation.
A further object is to provide a composite sealing ring including
an annular sealing jacket of Teflon or the like having a channel
cross section and a helically wound imperforate loading spring
having a channel cross section, and wherein the jacket provides a
protective shield for the spring.
A still further object is to provide a composite ring seal
structure in which the loading spring comprises a helically wound
flat strip having edge margins of successive convolutions in
overlapping relation so as to provide an imperforate surface, and
wherein the wound strip structure is deformed transversely into a
channel configuration.
Another object is to provide a ring seal loading spring of
helically wound construction which is transversely of channel
configuration, and wherein the channel embodies double imperforate
walls.
Still another object is to provide an improved method of
fabricating an annular loading spring and associated jacket to
provide a composite ring seal structure.
It is also an object to provide an improved imperforate helically
wound ring seal loading spring, and method of fabricating the
same.
Further objects and advantages of the invention will be brought out
in the following part of the specification, wherein detailed
description is for the purpose of fully disclosing a preferred
embodiment of the invention without placing limitations
thereon.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to the accompanying drawings, which are for illustrative
purposes only:
FIG. 1 is a sectional view through a ring seal embodying the
features of the present invention as it would appear when installed
in a seal cavity;
FIG. 2 is an enlarged transverse sectional view through a strip
such as used for fabricating the spring means embodied in the ring
seal of the present invention;
FIG. 3 is an elevational view, partly in section of mechanism for
winding the spring strip;
FIG. 4 is a sectional view of the same, taken substantially on line
4-4 of FIG. 3;
FIG. 5 is an enlarged view of the wound strip as it appears during
the winding operation, portions being in section to show the
overlap of the edge margins of the successive convolutions;
FIGS. 6, 7, and 8 are enlarged fragmentary perspective views
showing the successive steps for joining the ends of a length of
the helically wound strip to provide a ring configuration for the
seal spring;
FIG. 9 is a sectional view taken substantially on line 9-9 of FIG.
8;
FIG. 10 is an enlarged plan view of the spring ring as it appears
prior to deformation into its final channel configuration;
FIG. 11 is a view illustrating mechanism for deforming the spring
ring, by means of cooperable die members shown in open
position;
FIG. 12 is a fragmentary view showing the die members in closed
position with the deformed ring therein;
FIG. 13 is an enlarged fragmentary perspective showing the channel
configuration of the spring, including a transverse section
therethrough to indicate the double-walled structure thereof;
FIG. 14 is an enlarged fragmentary perspective view showing the
preformed seal jacket as initially applied to the completed spring
means during fabrication of the ring seal; and
FIG. 15 is an enlarged fragmentary view illustrating the completed
composite ring seal, a transverse section being taken therethrough
for disclosing the cooperative association of the jacket and spring
parts.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring more specifically to the drawings, there is shown therein
a composite sealing ring as generally indicated at 10 which
embodies the features of the present invention and essentially
includes a flexible annular jacket A and associated loading spring
means B mounted in the jacket to reinforce and resist undue
deformation thereof, as well as energize the jacket to assure a
proper sealing action thereof.
As best shown in FIGS. 1 and 15, the jacket is constructed with a
ring configuration having a channel-shaped cross section. More
specifically, this jacket is fabricated so as to provide outer and
inner circumferentially extending sidewalls 11a and 11b which
extend over the associated sidewalls 12a and 12b of the loading
spring means B. The loading spring structure B, as in the case of
the jacket, is of ring configuration with a channel cross section
which is U-shaped, the sidewalls 12a and 12b being bridged by
bottom wall portion 12c. As will be seen in FIG. 1, the bottom wall
portion of the loading spring means is intimately engaged by
inwardly extending wall portions 13a and 13b which are integrally
formed with the jacket sidewalls and extend inwardly into embracing
engagement with the bridging wall portion of the loading spring
means. At the opposite end, the sidewalls 11a and 11b are
interconnected by an integrally formed wall portion 11c, this
portion being deflected between its ends so as to provide inner
sidewalls 14a and 14b connected by a bridging wall 14c which are
conformed to the inner wall surfaces of the loading spring means.
As thus arranged, the loading spring means is of substantially
U-shaped cross section, while the jacket is of substantially
W-shaped cross section. Thus, the jacket provides a protecting
shield for the spring means with respect to its side opening and
prevents the sealed medium from coming into contact with the
loading spring means. At this end of the jacket, the sidewalls 11a
and 11b are respectively provided with circumferentially extending
sealing surface faces 15a and 15b which are adapted to engage
circumferentially extending surfaces 16a and 16b which are to be
sealed when the sealing ring is positioned within a seal cavity 17
which is in communication with a source of fluid pressure through
an annular passage as indicated by numeral 18. The seal cavity is
provided with a backup wall 19 which provides an abutment surface
for circumferentially extending end faces 20a and 20b formed
respectively on the wall portions 13a and 13b. Adjacent the
surfaces 16a and 16b, the wall portions 13a and 13b have
circumferentially extending surfaces 21a and 21b which are slightly
recessed with respect to the sealing faces 15a and 15b so as to
provide a small clearance.
It is preferred that the jacket A be formed of a tough, durable,
flexible material such as polytetrafluoroethylene resin, commonly
known as "Teflon" or some similar plastic material having the
desired characteristics, and which will permit the fabrication of
the jacket so as to have the preferred configuration as explained
above by using extrusion, molding, or machining processes as
conventionally employed.
A main feature of the present invention resides in the unique
construction embodied in the loading spring, and the method of its
fabrication and embodiment into the composite sealing ring
structure as described above. A most important factor contributing
to the success of applicant's sealing ring resides in a design
concept which permits the utilization of a spring unit which
embodies a helically coiled spring element in a manner whereby the
inherent disadvantages of conventional arrangements will be
successfully eliminated. It is believed that the construction of
the loading spring unit will be best understood by explaining the
method or manner of its fabrication.
In the first instance, a strip 22 of flat ribbonlike material, for
example, stainless steel or other suitable material is helically
wound into the form of a flexible tube in such a manner that the
marginal edges of successive convolutions will have overlapping
relationship in which the leading edge 24 of each convolution will
be outwardly exposed, while the trailing edge of the convolutions
as indicated at 25 will be concealed by successive strip turns.
The mechanism for winding such a tube may vary as to details. One
embodiment of a mechanism for this purpose is disclosed in FIGS. 3
and 4 as including a frame member 26 having edge seating flanges
27-27. An annular hub 26' on one side is positioned between these
flanges and extends outwardly from a surrounding recessed planar
surface 27a. An associated plate member 28 is provided with an
opening 29 adapted to receive the hub thereinto to permit mounting
of the plate 28 into assembled relation in face engagement with the
seating flanges 27-27 in which position it can be secured by
threaded screws 30. The hub 26' and associated plate 28 are
provided with a series of aligned passages 31 which rotatably
support a mandrel 32 therein. At one side of plate 28, the mandrel
32 extends through a winding passage 33 of sufficiently increased
diameter to permit the winding of the tube structure 23 therein. At
the inner end of the passage 33, the strip 22 is fed edgewise to
the mandrel through the space 34 between the inner surface of plate
28 and the recessed planar surface 27a during a winding
operation.
It has been found, however, that advantageous results are obtained
and that it is possible to secure a smoother outer surface on the
tube 23, if the leading edge 24 of the strip 22 is thinned by a
stretching operation as shown in FIG. 2, prior to winding upon the
mandrel. In the disclosed mechanism, this stretching and thinning
operation is accomplished by carrying the entering strip edgewise
around the hub 26' in an arcuate path as generally indicated at 35
so that the edge 24 of the entering strip will be radially
outwardly positioned with respect to the edge 25.
Following the winding of the strip upon the mandrel, the wound
strip is heated to a suitable temperature, for example, a
temperature of the order of 900.degree. F. in the case of stainless
steel materials to relax the material and achieve a tightening of
the winding. After treatment in this manner, the wound strip is
removed from the mandrel, cleaned, and cut to required lengths.
The cut length of tube 23 is then formed into a circular or a ring
configuration 36 (FIG. 10) by juxtaposing the opposite ends of the
tube length, as shown in FIG. 6, wherein opposite ends of the
strip, as indicated at 22a and 22b, are positioned so that upon
telescoping the ends of the tubular structure, the strip ends 22a
and 22 b, may be easily guided and worked into an overlapping
initial engagement, as shown in FIG. 7. By continuing to push the
ends of the tube together, and the exercise of a slight twisting
movement, the overlapped strip ends 22a and 22b may be caused to
reach a desired fully lapped engagement as shown in FIGS. 8 and
9.
Having thus formed the ring configuration 36, this ring is now
deformed into a channel configuration having a substantially
U-shaped cross section. One mechanism for deforming the ring
configuration 36 is disclosed in FIGS. 11 and 12 as comprising a
lower female die member 37 and an operatively associated upper male
die member 38, the die members being supported for relative
movement to open and closed positions. The female die member is
disclosed as having an annular groove 39 having an upwardly opening
side defined by outer and inner concentric walls 40a and 40b
leading downwardly to downwardly converging sidewall portions 41a
and 41b respectively, which are interconnected at their lower
extremities by a curved bottom wall 41c. As thus arranged, a ring
36 may be placed in an initial position at the upper end of the
annular groove between the concentric walls 40a and 40b.
The male die member 38 is provided with an appropriate annular
projection 42 which is provided at its base portion with inner and
outer concentric wall portions 43a and 43b which lead to downwardly
converging wall portions 44a and 44b, which terminate at their
lower extremities in a curved end portion 44c.
The annular groove 39 and annular projection 42 are so dimensioned
that when the die members 37 and 38 are moved into closed position,
as shown in FIG. 12, the inserted ring 36 will be deformed into the
bottom of the groove 39 in such a manner as to produce a double
walled U-shaped channel configuration such as forms the loading
spring means B of the composite sealing ring of the present
invention. When deforming the ring 36, it is desirable to allocate
the ring so that the overlapped strip ends 22a and 22b will be
positioned within the bottom of the channel as shown in FIG. 13.
The overlapped ends are then spot welded together as indicated at
45.
The deformed, U-shaped spring structure is then passivated and is
ready for assembly into the preformed jacket structure A as shown
in FIG. 14 for the final assembly operation. With the jacket A and
loading spring means B oriented as shown in FIG. 14, with the
sidewalls 11a and 11b of the jacket outwardly spaced with respect
to the sidewalls 12a and 12b of the spring means, so that the wall
portion 11c is of straight undeformed configuration, the assembled
parts are placed in a suitable mold where they are heated to a
temperature of substantially 250.degree. F. and then cooled. During
this operation the wall portion 11c is deflected into the channel
of the spring means, and the sidewalls 11a and 11b moved into
engaged position with the sidewalls 12a and 12b to provide the
finished structure as shown in FIG. 15.
Although the ring seal has been described above as having the
jacket A separately formed and assembled with the loading spring B,
it is contemplated within the broad concept of the invention that
the loading spring may have the sealing material applied directly
as a surface coating or covering. The sealing material in such case
would include any of a variety of materials such as plastics,
metals, e.g., lead, and the like, which would be applied to the
spring material either prior to or after the coiling operation.
From the foregoing description and drawings, it will be clearly
evident that the delineated objects and features of the invention
will be accomplished.
Various modifications may suggest themselves to those skilled in
the art without departing from the spirit of the invention and,
hence, I do not wish to be restricted to the specific form shown or
uses mentioned, except to the extent indicated in the appended
claims.
* * * * *