U.S. patent application number 12/573898 was filed with the patent office on 2010-03-25 for watertube and method of making and assembling same within a boiler or heat exchanger.
This patent application is currently assigned to BURNHAM HOLDINGS, INC.. Invention is credited to Edward A. BENDER, Thomas Wayne MOORE.
Application Number | 20100071635 12/573898 |
Document ID | / |
Family ID | 42036329 |
Filed Date | 2010-03-25 |
United States Patent
Application |
20100071635 |
Kind Code |
A1 |
MOORE; Thomas Wayne ; et
al. |
March 25, 2010 |
WATERTUBE AND METHOD OF MAKING AND ASSEMBLING SAME WITHIN A BOILER
OR HEAT EXCHANGER
Abstract
A one-piece tube for use as a watertube within a watertube
boiler or heat exchanger has a free end section that is formed to
have an integral, outward-extending circumferential ring, or
flange, a spaced distance from an adjacent end face of the tube. A
boiler is provided that has an elongate header and a plurality of
separate watertubes each having an intermediate section and
opposite end sections. An end section of each watertube is
connected to the header. The intermediate section of each watertube
has a substantially constant outer diameter along its full length
and is closely spaced to adjacent watertubes within the combustion
chamber. At least one of the end sections of each watertube has a
transition that reduces the diameter of the watertube as it extends
from the intermediate section to an outwardly-extending
circumferential flange. This arrangement permits close spacing of
the connection sites of the watertubes to the header and permits
the connection sites to be provided in a linear array.
Inventors: |
MOORE; Thomas Wayne; (Bunker
Hill, IN) ; BENDER; Edward A.; (Peru, IN) |
Correspondence
Address: |
MCNEES WALLACE & NURICK LLC
100 PINE STREET, P.O. BOX 1166
HARRISBURG
PA
17108-1166
US
|
Assignee: |
BURNHAM HOLDINGS, INC.
Lancaster
PA
|
Family ID: |
42036329 |
Appl. No.: |
12/573898 |
Filed: |
October 6, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11380456 |
Apr 27, 2006 |
|
|
|
12573898 |
|
|
|
|
Current U.S.
Class: |
122/235.14 ;
122/235.15 |
Current CPC
Class: |
B21D 41/04 20130101;
F28D 7/082 20130101; F28D 7/08 20130101; F24H 1/40 20130101; F28D
1/0477 20130101; F28F 9/12 20130101 |
Class at
Publication: |
122/235.14 ;
122/235.15 |
International
Class: |
F22B 37/10 20060101
F22B037/10 |
Claims
1. A watertube for use to conduct water or steam, the watertube
comprising: an intermediate portion having a first end portion and
a second end portion; the first end portion having an integrally
formed, radially outward-extending circumferential flange spaced
from a free end of the first end portion, the flange formed to
accept a driving force applied in a direction parallel to the
longitudinal axis of the first end portion toward the free end of
the first end portion without failing; a radially extending surface
on a distal side of the flange, the radially extending surface
being dimensioned to engage an apparatus which exerts the driving
force; the first end portion having a tapered outer wall which
tapers down from the flange to the free end of the first end
portion; whereby an axial force applied to the radially extending
surface of the flange results in the tapered first end portion
being received in an opening of a manifold and secured in
fluid-tight engagement therein.
2. The watertube as recited in claim 1, wherein the intermediate
portion has a serpentine configuration.
3. The watertube as recited in claim 1, wherein the first end
section has been compressed along its axial length to form the
flange.
4. The watertube as recited in claim 1, wherein the tapered outer
wall of the first end portion has a frustoconical
configuration.
5. The watertube as recited in claim 1, wherein a fastener is
positioned on the flange to ensure that the first end portion of
the watertube will be retained in the opening of the manifold.
6. The watertube as recited in claim 1, wherein the flange is
continuous about the circumference of the first end portion of the
watertube.
7. The watertube as recited in claim 1, wherein the tapered outer
wall has a non-uniform, varying taper configuration.
8. The watertube as recited in claim 1, the second end portion
comprising: an integrally formed, radially outward-extending,
circumferential second flange spaced from a free end of the second
end portion, the second flange formed to accept a driving force
applied in a direction parallel to the longitudinal axis of the
second end portion in a direction toward the free end of the second
end portion without failing; a second radially-extending surface on
a distal side of the second flange, the second radially-extending
surface being dimensioned to engage an apparatus which exerts the
driving force; the second end portion having a tapered second outer
wall which tapers down from the second flange to the free end of
the second end portion; whereby an axial force applied to the
second radially-extending surface of the second flange results in
the tapered second end portion being received in an opening of a
manifold and secured in fluid-tight engagement therein.
9. A boiler, comprising: an elongate header located adjacent the
boiler; a plurality of watertubes each having an intermediate
section and an end section, the end section of each of the
watertubes connecting to the header; the intermediate section of
each of the watertubes having a substantially constant outer
diameter; the end section of each of the watertubes having a
transition that reduces the diameter of the watertube as it extends
from the intermediate section; and the end section of each of the
watertubes having an outwardly-extending circumferential flange
located on an opposite side of said transition from said
intermediate section such that said flange extends from a part of
said end section of reduced diameter.
10. A boiler according to claim 9, wherein the outwardly-extending
circumferential flange has a peripheral outer edge of a
predetermined diameter that closely matches or is not significantly
greater than the outer diameter of the intermediate section.
11. A boiler according to claim 9, wherein the header has a series
of sockets for receiving a portion of the end sections of the
watertubes, and wherein the series of sockets of the header is
provided solely as a closely-spaced, non-staggered, linear array of
sockets.
12. A boiler according to claim 9, wherein a fastener is secured to
the header between each of said sockets and extends over and
engages top surfaces of the outwardly-extending circumferential
flanges of an adjacent pair of the watertubes to prevent withdrawal
of the watertubes from the sockets.
13. A boiler according to claim 9, wherein each of the watertubes
are identical and made of a single length of tube with integral end
sections having the transition and outwardly-extending
circumferential flange formed by a forming operation.
14. A boiler according to claim 9, wherein each of the watertubes
are identical and include an end fitting welded thereto for
providing the outwardly-extending circumferential flange.
15. A boiler according to claim 9, wherein the watertubes each have
a second end section which extends from the intermediate section,
the second end section of each of the watertubes including said
transition and said outwardly-extending circumferential flange.
16. A boiler according to claim 9, wherein the intermediate section
of each of the watertubes extends in a non-linear, serpentine
path.
17. A watertube and header assembly for a boiler or heat exchanger,
comprising: an elongate, hollow header extending within the boiler
or heat exchanger; and a plurality of separate, closely-spaced,
elongate watertubes extending from the header; each of the
watertubes having an intermediate section and at least one end
section, the end section of each of the watertubes being connected
to the header; the intermediate section of each of the watertubes
having a substantially constant outer diameter along its full
length and being closely spaced to adjacent watertubes; and the end
section of each of the watertubes having a transition that reduces
the diameter of the watertube as it extends from the intermediate
section.
18. A watertube and header assembly according to claim 17, wherein
an outwardly-extending circumferential flange is located on an
opposite side of the transition relative to the intermediate
section such that the flange extends from a reduced-diameter part
of the end section.
19. A watertube and header assembly according to claim 18, wherein
the outwardly-extending circumferential flange has a peripheral
outer edge of a predetermined diameter that closely matches the
outer diameter of the intermediate section.
20. A watertube and boiler assembly according to claim 19, wherein
the header has a series of sockets for receiving free end tip
portions of the end sections of the watertubes, the series of
sockets being provided as a closely-spaced linear array of sockets
along a length of the header.
21. A watertube and boiler according to claim 20, wherein a
fastener is secured to the header between each of the sockets and
extends over and engages upper surfaces of the outwardly-extending
circumferential flanges of an adjacent pair of the watertubes to
prevent withdrawal of the free end tip portions of the watertubes
from the sockets.
22. A watertube for a boiler or heat exchanger, comprising an
intermediate section and opposite end sections, the intermediate
section having a substantially constant outer diameter along its
full length and having bends providing the intermediate section
with a serpentine-like shape, each of the opposite end sections
having a transition that reduces the diameter of the watertube as
it extends from the intermediate section to an outwardly-extending
circumferential flange located on an opposite side of the
transition relative to the intermediate section such that the
flange extends from a part of the section of reduced diameter, the
outward-extending circumferential flanges having a peripheral outer
edge of a predetermined diameter that closely matches the outer
diameter of the intermediate section.
23. A watertube according to claim 22, wherein the transitions and
outwardly-extending circumferential flanges are integral, formed
parts of the watertube.
24. A watertube according to claim 22, wherein the
outwardly-extending circumferential flanges are provided by
separately-manufactured end fittings that are welded to the end
sections.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This Application is a continuation-in-part application of
U.S. Utility application No. Ser. 11/380,456, filed Apr. 27, 2006,
and entitled "Watertube and Method of Making and Assembling same
within a Boiler or Heat Exchanger."
FIELD OF THE INVENTION
[0002] The present invention relates to a boiler and/or heat
exchanger used in a domestic and/or commercial heating and/or hot
water and/or steam system, and more specifically, the present
invention relates to a watertube structure and to methods of making
a watertube and assembling it within a boiler and/or similar heat
exchanger. The invention also relates to a watertube, a header and
watertube assembly, a boiler having the header and watertube
assembly, and a method of assembling the boiler.
BACKGROUND OF THE INVENTION
[0003] Examples of boilers having watertubes are provided by U.S.
Pat. No. 1,824,256 issued to Bryan and U.S. Pat. No. 4,993,368
issued to Jones et al. For example, the Bryan patent discloses a
boiler having a plurality of bent watertubes extending through a
combustion chamber. The ends of the bent watertubes connect to the
upper and lower domes of the boiler via separately manufactured
tapered fittings.
[0004] A return pipe of the heating system is connected to the base
header for returning cool water or like fluid to the boiler. The
cool water or like fluid flows upward into the plurality of
closely-spaced watertubes where the water or like fluid is heated
as it passes through and/or adjacent the combustion chamber. A
delivery pipe connects to the top of the dome header which receives
the heater water, like fluid, or steam from the watertubes and
delivers the steam and/or heated water or fluid to the system via
the delivery pipe.
[0005] Typically, such a boiler will have a front and a rear with
the headers extending horizontally in a front-to-rear direction at
the top and bottom of the boiler. A plurality of closely-spaced
watertubes typically having undulating intermediate sections
extends through the combustion chamber. The upper end sections of
the watertubes connect to the dome header, and lower end sections
connect to the base header. Each watertube essentially extends
through the boiler within a vertically-disposed plane that is
parallel with the front and rear of the boiler and that is parallel
to all other planes defined by the other watertubes.
[0006] Each manifold, dome, header, or like casting is typically
provided in the form of an elongate hollow pipe or the like that
has a relatively large diameter as compared to the diameter of the
watertubes. Conventionally, the end sections of the watertubes
connect to the manifolds, headers, domes, or castings via
separately manufactured nipple fasteners or end fittings.
[0007] A conventional watertube for a boiler and/or heat exchanger
is typically made of a metallic material and has substantially
constant inner and outer diameters from end-to-end. The
intermediate sections of the tubes extend in various bent,
serpentine, or other shapes or patterns between opposite free ends.
A separately-manufactured tapered fitting is typically welded to
each free end to enable the tubes to be connected in a fluid-tight
and secure manner to domes, manifolds, headers and/or like
castings.
[0008] The separately-manufactured fitting typically provides the
end of the tube with an outwardly-extending circumferential ring
and a tapered end section. The tapered end section is inserted into
a corresponding tapered hole, port or socket in a dome, manifold,
headeror like casting. A clip, clasp or like fastener is typically
applied to the circumferential ring to ensure that the inserted
tube end remains in engagement with the dome, manifold, header or
like casting.
[0009] A 45 degree angle fillet weld is typically used to connect
the fitting to the tube. The 45 degree angle fillet weld extends
from an upper, exposed, radially-extending end surface of the
circumferential ring to the adjacent outer wall surface of the
tube. A problem with the use of the fillet weld is that the fillet
weld eliminates any clean or flat surface of the circumferential
flange on which a force can be readily applied to drive the tube
end into the hole in a dome or the like. Existence of the fillet
weld further complicates the already difficult and inefficient
process of handling relatively heavy tubes within small spaces
available during a boiler or heat exchanger assembly and the
process of driving the tube ends into position within the boiler in
a manner that provides leak-free connections.
[0010] Accordingly, there is a need for a watertube structure that
can be handled and driven more easily into a hole, port or socket
of a dome, manifold, or casting to create a leak-free connection
therewith. In addition, there is a need for an efficient process of
assembling watertubes in boilers and heat exchangers and for making
watertubes.
[0011] The conventional watertube is made of steel, has constant
inner and outer diameters from end-to-end, and weighs at least
about fifty pounds. The intermediate sections extend in various
bent, serpentine, or other shapes as they extend within the
combustion chamber of boiler. The separately-manufactured fittings
are typically welded to each free end to enable the ends of the
watertubes to be connected in a fluid-tight and secure manner to
water domes, manifolds, headers and like castings as discussed
above.
BRIEF SUMMARY OF THE INVENTION
[0012] According to a first aspect of the present invention, a
watertube for use to conduct water or steam is provided. The
watertube has an intermediate portion with a first end portion and
a second end portion. The first end portion has an integrally
formed radially outward extending, circumferential flange which is
spaced from a free end of the first end portion. The flange is
formed to accept a driving force applied in a direction parallel to
the longitudinal axis of the first end portion toward the free end
of the first end portion without failing. A radially extending
surface on a distal side of the flange is provided. The radially
extending surface is dimensioned to engage an apparatus which
exerts the driving force thereon. The first end portion has a
tapered outer wall which tapers down from the flange to the free
end of the first end portion. The application of an axial force to
the radially extending surface of the flange results in the tapered
first end portion being received in an opening of a manifold and
secured in fluid-tight engagement therein.
[0013] According to another aspect of the present invention, a
method of making a tube for a boiler or heat exchanger is provided.
A one-piece tube for use as a watertube within a boiler or heat
exchanger has a free end section of a predetermined
substantially-constant diameter. The method includes the step of
forming an integral, outward-extending circumferential ring, or
flange, on the free end section of the tube a spaced distance from
an adjacent end face of the tube. This may be accomplished by
radially expanding the tube within the free end section followed by
axially compressing the free end section to cause a portion of the
tube to bulge radially outward to form the circumferential ring or
flange. The method can also include the step of forming the free
end section of the tube that extends from the circumferential ring,
or flange, to the adjacent end face of the tube with a taper such
that the diameter of an outer wall of the tube progressively
decreases from the circumferential ring, or flange, to the end
face. Preferably, the tube is made of a metallic material and the
forming process is cold or hot forming process.
[0014] According to yet another aspect of the present invention, a
method of assembling a watertube boiler or heat exchanger is
provided. A one-piece metallic tube having a free end section of a
predetermined substantially-constant diameter is cold and/or
hot-formed to produce an integral circumferential flange extending
outwardly from the tube a spaced distance from an adjacent end face
of the tube. A force is applied on a radially-extending surface of
the circumferential flange to drive the end of the metallic tube
into a hole, port or socket of a dome, manifold or like casting of
a watertube boiler or heat exchanger to secure the one-piece tube
to the dome, manifold, header or like casting. Before being engaged
with the dome, manifold, header or like casting, the free end
section of the metallic tube that extends from the circumferential
flange to the adjacent end face can be formed with a taper such
that the diameter of an outer wall of the tube progressively
decreases from the circumferential flange to the end face.
[0015] According to yet another aspect of the present invention, a
boiler or heat exchanger is provided. The boiler or heat exchanger
has at least a pair of opposed domes, manifolds, or like castings
and one or more metallic watertubes each having opposite ends
connected to the opposed domes, manifolds, or like castings. At
least one end section of the one-piece watertube is formed to have
an integral outwardly-extending circumferential flange. The flange
provides a readily-engagable, radially-extending surface on which a
substantially axially-directed force can be applied to drive the
end of the tube into sealing engagement with a hole, port, or
socket of one of the domes, manifolds, or like castings.
Preferably, a portion of the tube extending from the
circumferential flange to an adjacent end face of the tube is
formed with an inward taper such that a diameter of an outer wall
of the tube progressively decreases from the circumferential flange
to the end face. A wall defining the hole, port, or socket in the
dome, manifold or like casting can be tapered to enable tight
engagement with the tapered end of the tube. The watertube can have
a substantially serpentine shape between its opposite ends.
[0016] According to yet another aspect of the present invention, a
boiler is provided that has an elongate base header located
adjacent a base of the boiler, an elongate dome header located at
the top of the boiler, and a plurality of separate watertubes each
having an intermediate section and opposite end sections. An upper
one of the end sections of each watertube is connected to the dome
header and a lower one of the end sections of each watertube is
connected to the base header such that the intermediate section
extends through a combustion chamber of the boiler. The
intermediate section of each watertube has a substantially constant
outer diameter along its full length and is closely spaced to
adjacent watertubes within the combustion chamber. At least one of
the end sections of each watertube has a transition that reduces
the diameter of the watertube as it extends from the intermediate
section and transitions to a reduced-diameter free end tip of the
end section.
[0017] According to some embodiments, the above-referenced end
section of the watertube has an outwardly-extending circumferential
flange. The flange is located on an opposite side of the transition
from the intermediate section of the watertube such that the flange
extends from a reduced-diameter part of the end section adjacent
the free end tip. The outwardly-extending circumferential flange
has a peripheral outer edge of a predetermined diameter that
closely matches or is not significantly greater than the constant
outer diameter of the intermediate section. Further, the base
header and the dome header have a series of sockets for receiving
the tip portion of the end sections of the watertubes, and
preferably the series of sockets of at least one of the base header
and dome header is provided as a closely-spaced linear
(non-staggered) array of sockets.
[0018] According to yet another aspect of the present invention, a
watertube and header assembly for a boiler or heat exchanger is
provided and includes an elongate, hollow header extending within
the boiler or heat exchanger and a plurality of separate,
closely-spaced, elongate watertubes extending from the header. Each
of the watertubes has an intermediate section and at least one end
section. The end section is the part of the watertube that connects
to the header, and the intermediate section has a substantially
constant outer diameter along its full length and is closely spaced
to adjacent intermediate sections of like watertubes. The end
section of each watertube has a transition that reduces the
diameter of the watertube as it extends from the intermediate
section to an outward-extending circumferential flange located on
an opposite side of the transition relative to the intermediate
section. Thus, the flange extends from a part of the end section
having a reduced diameter. Preferably, the outward-extending
circumferential flange has a peripheral outer edge of a
predetermined diameter that closely matches the outer diameter of
said intermediate section, and the header has a series of sockets
for receiving the free end tip portions of the end sections of the
watertubes. The series of sockets are provided as a closely-spaced
linear array of sockets along a length of the header.
[0019] According to yet another aspect of the present invention, a
watertube for a boiler or heat exchanger is provided and comprises
an elongate tube having an intermediate section and opposite end
sections. The intermediate section has a substantially constant
outer diameter along its full length and bends providing the
intermediate section with a serpentine-like shape. Each of the end
sections has a transition that reduces the diameter of the
watertube as it extends from the intermediate section to an
outwardly-extending circumferential flange located on an opposite
side of the transition relative to the intermediate section. Thus,
the flange extends from a reduced-diameter part of the end section.
The outwardly-extending circumferential flange has a peripheral
outer edge of a predetermined diameter that closely matches the
outer diameter of the intermediate section.
[0020] According to a final aspect of the present invention, a
method of assembling a boiler is provided. The method includes the
steps of mounting an elongate hollow base header below a combustion
chamber of the boiler, mounting an elongate hollow dome header
above the combustion chamber of the boiler, and providing only a
linear array of sockets in each of the base and dome headers. A
plurality of watertubes is provided such that each of the
watertubes includes an intermediate section of substantially
constant outer diameter and opposite end sections. Each of the end
sections has a transition that reduces the outer diameter of the
watertube as it extends from the intermediate section to an
outwardly-extending circumferential flange located on an opposite
side of the transition relative to the intermediate section. Each
outward-extending circumferential flange has a peripheral outer
edge of a predetermined diameter that closely matches the outer
diameter of the intermediate section. The method further includes
the step of connecting the plurality of water tubes to the linear
array of sockets of the base and dome headers such that the
intermediate sections of the watertubes extend through the
combustion chamber of the boiler closely-spaced to intermediate
sections of the adjacent watertubes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The features and advantages of the present invention should
become apparent from the following description when taken in
conjunction with the accompanying drawings, in which:
[0022] FIG. 1 is a cross-sectional view of a watertube boiler
according to the above referenced prior art Bryan patent;
[0023] FIG. 2 is a view illustrating the staggered connection
pattern of prior art watertubes to a header;
[0024] FIG. 3 is a schematic view of a tube expansion method step
according to the present invention;
[0025] FIG. 4 is a cross-sectional view taken along line 3-3 of
FIG. 3;
[0026] FIG. 5 is a schematic view of a ring, or flange, forming
step according to the present invention;
[0027] FIG. 6 is a cross-sectional view taken along line 5-5 of
FIG. 5;
[0028] FIG. 7 is a schematic view of a taper forming step according
to the present invention;
[0029] FIG. 8 is a cross-sectional view taken along line 7-7 of
FIG. 7;
[0030] FIG. 9 is a perspective view of an end section of a formed
watertube according to the present invention;
[0031] FIG. 10 is a cross-sectional view taken along line 9-9 of
FIG. 9:
[0032] FIG. 11 is a front view of a watertube according to the
present invention;
[0033] FIG. 12 is a side view of the watertube of FIG. 11;
[0034] FIG. 13 is an enlarged view of an end section of the
watertube of FIG. 11;
[0035] FIG. 14 is a perspective view of a watertube and header
assembly according to the present invention;
[0036] FIG. 15 is a cross-sectional view taken along line 8-8 of
FIG. 14;
[0037] FIG. 16 is a cross-sectional view of the watertube of FIG.
11 assembled to a header according to the present invention;
and
[0038] FIG. 17 is a front elevation view of an assembly of the
watertube of FIG. 11 connected to upper and lower headers.
DETAILED DESCRIPTION OF THE INVENTION
[0039] The present invention relates to watertubes that are used in
commercial boilers, heat exchangers, and like apparatus. FIG. 1
illustrates an example of a watertube boiler 10 that is known in
the art. The boiler 10 includes at least one upper dome 12 and at
least one base header 16. The so-called bent watertubes 20 have
opposite ends interconnecting the base header 16 to the dome 12. A
serpentine portion of each watertube 20 extends within a combustion
chamber 22 of the boiler. System water is fed into the boiler 10 or
dome 12 and travels within the watertubes 20. The water is heated
in the watertubes 20 and the heated water or steam flows from the
watertubes 20 into the dome 12 and then to a system supply
pipe.
[0040] A typical watertube is made of a metallic material. The
inner and outer diameters of such a watertube are typically
constant from end-to-end. For example, the outer diameter of each
tube may be 1.5 inch, and the inner diameter of each tube may be
1.25 inch thereby providing a tube wall thickness of about 0.125
inch. The watertubes can extend in serpentine or other shaped paths
including linear shaped paths. The watertubes are assembled within
boilers, heat exchangers and like apparatus.
[0041] A watertube 30 according to the present invention is similar
to watertube 20 discussed above; however, the watertube 30 is
provided as one-piece without the use of separately-manufactured
fittings, nipples, or like coupling devices secured or welded
thereto. Rather, the watertube 30 according to the present
invention has a free end section that is formed into a desired
shape without any component being added or welded thereto.
Accordingly, there are no fillet welds or the like capable of
providing leakage paths.
[0042] The method of making the watertube 30 is shown in FIGS. 3-8.
A tube 30a is initially provided having an end section 32 with a
uniform and constant inner diameter and a uniform and constant
outer diameter. A holding clamp 34 is positioned about a portion of
the tube to grip the tube a predetermined spaced distance from an
adjacent end face 36 of the tube 30a. The holding clamp 34 rigidly
supports the tube relative to one or more dies 38 that are capable
of being inserted into the end section 32 to radially expand the
end section 32.
[0043] The die 38 shown in FIGS. 3 and 4 includes a tip 40 of a
diameter sufficiently small to permit insertion within the tube 30a
without resistance. An opposite end of the die 38 includes an
expansion section 42 that is larger in diameter than the inner
diameter of the tube 30. The die 38 also includes an intermediate
frustoconical section 44 that transitions the diameter of the die
38 from that of the tip 40 to that of the expansion section 42.
Accordingly, the outer and inner diameters of the tube 30 can be
radially expanded by inserting the die 38 therein with a
predetermined amount of force, and/or by sequentially inserting a
set of dies each having a progressively larger diameter expansion
section. Thus, end section 32 can be expanded to a desired inner
diameter D1.
[0044] After the end section 32 is expanded, an upsetting element
46 or the like engages the end face 36 and applies an axially
directed force thereon to thereby compress the axial length of the
end section 32. The upsetting element 46 can include an insertable
support section (not shown) that extends within the end section 32
of the tube 30 while the upsetting element 46 applies the desired
axial force. A face 48 of the holding clamp 34 has an annular
recessed molding area 50 into which the end section 32 bulges in
response to the axial compression. This results in the formation of
an integral, radially outward extending, circumferential ring, or
flange, 52. Preferably, the flange 52 includes a
radially-extending, substantially-flat surface 54 that is located
on a distal side of the flange 52 and that is readily engagable by
a forked or like driving tool (not shown) for reasons discussed in
greater detail below.
[0045] After the end section 32 is radially expanded and axially
compressed, one or more dies 56 is utilized to provide the end
section 32 with an outer diameter D2 that tapers inward from the
flange 52 to the end face 36. For example, the die 56 can have a
tapered inner surface 58 that is telescopically forced over the end
section 32 to thereby radially contract the outer and inner
diameters of the end section 32. In this way, the die 56, or a set
of dies, can be used to provide the end section 32 with a
frustoconical, or gradually tapered, outer wall 60.
[0046] As stated above, the tube 30 can be made of metallic
material, for example steel. Of course, watertubes made of other
materials can also be used. Preferably, the forming steps are cold
and/or hot-forming steps without the use of any stress-relieving
process steps, and both ends of the tube 30 can be formed as
described above. Accordingly, the watertube 30 is a one-piece tube
without separately-manufactured fittings or nipples and without
welded connections.
[0047] The watertube 30 having a formed end section 32 as shown in
FIGS. 9 and 10 can be assembled in a boiler, heat exchanger, or
like apparatus. Preferably, the boiler, heat exchanger, or like
apparatus has one or more pairs of opposed domes, headers,
manifolds, or like castings. These castings preferably have a
tapered hole, port or socket for receiving and engaging a tapered
end section 32 of the watertube 30. Accordingly, the end section 32
is aligned with the hole, port or socket and a force is applied to
drive the watertube into fluid-tight engagement with the dome,
manifold or like casting. For examples of boilers, domes, manifolds
and the like, the disclosures of U.S. Pat. Nos. 1,824,256 and
4,993,368 are incorporated herein by reference.
[0048] A forked tool (not shown) or the like is utilized to engage
the unobstructed, radially extending surface 54 of the
circumferential flange 52 and exert a substantially axially
directed force thereon to efficiently drive the tapered end section
32 into the hole, port, or socket. Thereafter, a clip, clasp or
like fastener can be placed over the flange 52 to ensure that it
remains engaged with the dome, manifold or like casting.
[0049] The above described methods, boiler, heat exchanger and like
apparatus provide watertubes that can be driven more efficiently
and more easily into domes, manifolds and the like. The use of
separate fittings and welds are eliminated thereby eliminating the
possibility of weld leaks and the like. In addition, a driving
force can be applied to the tube during the assembly process
without concern of creating leakage paths. The end forming process
also enables better control over tube tolerances with respect to
diameters, tapers and the like to further ensure the formation of
fluid-tight connections.
[0050] Various changes can be made to the above referenced methods
and apparatus. For example, the circumferential flange 52 can be
continuous or discontinuous, and the flange surface 54 can be of
shapes other than substantially-flat. For example, the flange can
be formed with a surface having a series of slots, recesses, or the
like adapted to engage the head of a driving tool. One or both ends
of the tube can have a formed end, and the tube can extend in a
bent or linear path. The taper of the end section can be a
gradually continuous uniform taper or a non-uniform varying taper.
Alternatively, a uniform, non-tapered end section can be
utilized.
[0051] Referring to FIG. 2 a conventional staggered pattern of
watertubes 112 connected to a header 120 is illustrated. As shown
in FIG. 2, the circumferential flanges 114 of the
separately-manufactured end fittings extend radially outward of the
outer diameter "A" of the watertubes 112. Thus, the existence of
the flanges 114 requires sufficient spacing between adjacent
watertubes. However, since a given number of closely-spaced
watertubes are required along a given length of the header, the
connections of the watertubes to the header must be staggered or
offset. As shown in FIG. 2, a spacing "B" is required between
adjacent watertubes 112 to accommodate the circumferential flanges
14, and the staggering of the connection sites permits the walls of
the intermediate sections of the watertubes 112 to have a spacing
"C" as viewed from the direction represented by arrow 126. A
disadvantage of the staggered pattern of connection sites is that
it requires the header 120 to be of an increased size or diameter
than otherwise would be desired or necessary.
[0052] With the above discussion in mind, a watertube 130 according
to the present invention is illustrated in FIGS. 11-14. The
watertube 130 has an undulating intermediate section 132 that
extends through the combustion chamber of a boiler. The outer
diameter "D" of the watertube 130 is substantially constant along
the full length of the intermediate section 132 and can be equal to
the outer diameter "A" of watertube 112. End sections 134 and 136
extend from the opposite ends of the intermediate section 132.
Somewhat similar to the circumferential flange 114 and tip 116 of
the watertube 112, the watertube 130 of the present invention can
also have outwardly-extending circumferential flanges 138 and free
end tips 140 which may or may not be tapered.
[0053] However, unlike the watertubes 112, the watertube 130 of the
present invention is not of a constant diameter between opposite
circumferential flanges 138. Rather, each end section, 134 and 136,
includes a transition 142 located between the intermediate section
132 and each circumferential flange 138. See FIG. 13. The
transition 142 reduces the inner and outer diameters of the
watertube 130 as it extends from the intermediate section 132
toward the circumferential flange 138. For example, the outer
diameter "E" of the transition 142 adjacent the circumferential
flange 138 is less than that of the outer diameter "D" of the
transition 142 adjacent the intermediate section 132. The
transition 142 can be provided by tapered walls as shown in FIG. 13
or by walls having a stepped configuration.
[0054] The circumferential flange 138, as illustrated in FIG. 13,
extends from a part of the watertube 130 having the reduced outer
diameter of "E," and its outermost circumferential edge extends to
a diameter of "F." The outer diameter "F" of the circumferential
flange 138 closely matches the outer diameter "D" of the
intermediate section 132 of the watertube 130. Accordingly, the
existence of the outwardly-extending circumferential flanges 138
from the end sections, 134 and 136, provides no limitation with
respect to close-spacing of watertubes 130 where they connect to a
header. For example, as best illustrated in FIG. 14, the watertubes
according to the present invention can be closely-spaced together
in a linear pattern where they extend from header 144 despite the
presence of the circumferential flanges.
[0055] Accordingly, the transition 142 of the watertube 130
adjacent the circumferential flange 138 accommodates the existence
of the outwardly-extending circumferential flange 138, thereby
eliminating any spacing requirements as a result of the
circumferential flange 138. For example, see FIG. 16 Thus, the
watertubes 130 can be spaced together as close as desired in any
pattern, linear or otherwise. This, in turn, enables the size or
diameter of the header 144 to be reduced. For example, the header
120 required by the staggered pattern of FIG. 2 may need to have a
diameter of at least about eight inches to accommodate the offset
spacing of the connection sites; whereas, for similar-sized
watertube diameters, the header 144 in FIGS. 14-17 may require a
diameter of only three inches due to the linear connection site
pattern. This provides advantages with respect to increasing the
velocity of the fluid through the boiler, improving convective heat
transfer within the boiler, and reducing costs with respect to
making and assembling the boiler.
[0056] In the embodiment of the present invention illustrated in
FIGS. 11-13 and 16, the end sections 134 and 136 of the watertube
130 are produced as a result of a forming operation applied to the
ends of the watertube 130. Thus, the watertube 130 comprises a
single piece of tube in which the transition sections 142 and
circumferential flanges 138 are formed using appropriate forming
dies or the like.
[0057] In contrast, FIGS. 14 and 15 illustrate another embodiment
of a watertube 150 according to the present invention. These
watertubes have separately applied end fittings 152. The end
fitting 152 is secured to a free end of the watertube 150, such as
by being welded thereto (the existence of the fillet weld is not
shown for purposes of ease of illustration). An intermediate
section 154 of the watertube 150 can have a constant outer diameter
between opposite end sections. However, at end sections of the
watertubes 150, where the watertubes 150 are required to connect to
manifolds, headers, domes or like castings 144, the watertubes 150
are provided with a transition 156 that tapers inward from the
intermediate section 154 to a reduced outer diameter section 158.
The end fitting 152 is secured to the reduced outer diameter
section 158 and the circumferential flange 160 provided by the end
fitting 152 extends outward from the reduced diameter section 158.
As discussed above, the transition 156 enables the outer diameter
of the circumferential flange 160 to substantially and closely
match the outer diameter of the intermediate section 154. Thus, the
existence of the circumferential flange 160 does not restrict close
spacing of adjacent watertubes 150 regardless of the connection
pattern (staggered, linear, or otherwise).
[0058] The transitions 142 and 156 of the watertubes 130 and 150
also accommodate the installation of clips, clasps, fasteners or
the like 162 that mechanically secure the watertubes 130 and 150 to
the headers, manifolds, domes, castings or the like 144. For
instance, as illustrated in FIGS. 14-16, threaded shafts 164 extend
from the header 144 and permit the placement of washers 166 or the
like that overlap with engage the upper surfaces of circumferential
flanges 138 and 160 of adjacent watertubes 130 and 150 and secure
the watertubes 130 and 150 to the header 144 via placement of a
securement nut 168 or the like. Of course, other fastening
mechanisms can be used. Thus, the transitions 142 and 156 not only
permit close spacing of watertubes 130 and 150 on the header 144,
but also accommodate placement of fasteners 162 that prevent
undesired withdrawal of the watertubes 130 and 150 from the header
144 during assembly or use.
[0059] FIG. 17 provides a simplified example of a boiler 170 having
watertubes 130 and headers 144. The headers 144 are illustrated as
being in the form of pipes of a given diameter. This diameter can
be reduced as desired due to the use of a linear connection pattern
of the watertubes to the header; for instance, see the linear
pattern of FIG. 14. A combustion chamber 172 is located at an
elevation between the headers 144, and the watertubes 130 extend
from the base header through the combustion chamber 172 to the
upper header.
[0060] The watertubes of the present invention can be efficiently
and readily driven into water domes, manifolds, headers and the
like despite their close spacing. In addition, the end forming
process used to form the ends of watertube 130 enables better
control over tube tolerances with respect to diameters, tapers and
the like to ensure the formation of fluid-tight connections.
[0061] Various changes can be made to the above-referenced
watertubes, assemblies, and methods of assembly. For example, the
circumferential flanges can be continuous or discontinuous, and can
be formed with a surface having a series of slots, recesses, or the
like adapted to engage the head of a driving tool. Alternatively,
the watertubes can be provided with ends not having circumferential
flanges. Also one or both ends of the watertube can have a formed
end, and the intermediate section of the watertube can extend in a
bent or linear path. The taper of the transition can be a gradually
continuous uniform taper or a non-uniform varying taper.
[0062] Accordingly, the present invention provides a watertube
configuration and watertube-to-header assembly that permits
close-spacing of adjacent watertubes without the use of staggered
connection patterns. Further, the headers or manifolds to which the
watertubes of the present invention connect can be provided of
smaller diameters or sizes yet still enable a desired number of
watertubes to be connected thereto in a closely-spaced manner. The
benefits that will be achieved with such an assembly include
improving the velocity of the water, steam, or like fluid through
the watertube and header assembly, improving convective heat
transfer to the water or like fluid, and reducing manufacturing and
assembly costs.
[0063] While preferred watertubes, assemblies and methods have been
described in detail, various modifications, alterations, and
changes may be made to the present invention without departing from
the spirit and scope of the present invention as defined in the
appended claims.
* * * * *