U.S. patent application number 13/833771 was filed with the patent office on 2013-08-08 for exothermic welding assembly.
This patent application is currently assigned to HARGER, INC.. The applicant listed for this patent is Harger, Inc.. Invention is credited to Mark S. Harger, Curtis R. Stidham.
Application Number | 20130199747 13/833771 |
Document ID | / |
Family ID | 40843823 |
Filed Date | 2013-08-08 |
United States Patent
Application |
20130199747 |
Kind Code |
A1 |
Stidham; Curtis R. ; et
al. |
August 8, 2013 |
EXOTHERMIC WELDING ASSEMBLY
Abstract
An assembly is disclosed for exothermic welding comprising a
mold which is formed of a material which withstands exothermic
welding temperatures and includes a weld cavity therein for
positioning at least two members which are to be exothermically
welded together, and an ignition cavity communicating with the weld
cavity. The mold is capable of accommodating any one of several
exothermic welding procedures which may involve either a flint
igniter or the use of an electrical igniter which is readily
accommodated by the mold in the performance of several of the
procedures. The electrical igniter is formed of a pair of flat,
longitudinally extending conductor strips with a sheet of
insulation laminated therebetween, a filament adjacent one end of
the strips, and one or more positioning tabs adjacent one end of
the strips. A cartridge is also provided which contains the weld
metal and the electrical igniter and which may be positioned in the
ignition cavity of the mold. The cartridge is formed of a material
which is consumed during the welding procedure and may contain a
plate of a different material adjacent its bottom which melts at a
higher temperature than the materials of the cartridge.
Inventors: |
Stidham; Curtis R.; (Medina,
OH) ; Harger; Mark S.; (Libertyville, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Harger, Inc.; |
Grayslake |
IL |
US |
|
|
Assignee: |
HARGER, INC.
Grayslake
IL
|
Family ID: |
40843823 |
Appl. No.: |
13/833771 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13091863 |
Apr 21, 2011 |
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13833771 |
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11969572 |
Jan 4, 2008 |
7950568 |
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13091863 |
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Current U.S.
Class: |
164/250.1 ;
164/333 |
Current CPC
Class: |
B22C 9/06 20130101; B23K
23/00 20130101 |
Class at
Publication: |
164/250.1 ;
164/333 |
International
Class: |
B22C 9/06 20060101
B22C009/06 |
Claims
1. An exothermic welding assembly comprising: a mold portion having
a first cavity therein for positioning at least two members
adjacent each other for exothermic welding, the mold portion
including an exterior surface with an annular groove, and a second
cavity in communication with the first cavity and configured for
seating a cartridge containing a weld metal and a portion of an
igniter; and a cover portion having an exterior surface with an
annular projection configured for sealingly engaging the annular
groove, the cover portion further including a chamber in
communication with the second cavity and configured for
accommodating a filter for trapping emissions created during the
exothermic welding.
2. The assembly of claim 1, further including a preconstructed
cartridge defining a chamber that contains particulate weld metal
prior to ignition.
3. The assembly of claim 2, wherein the cartridge includes a bottom
wall formed of a material that melts with the particulate weld
metal during the exothermic welding.
4. The assembly of claim 2, wherein the cartridge further includes
a filament end of the igniter.
5. The assembly of claim 4, wherein the filament end is formed of a
material that melts with the particulate weld metal during the
exothermic welding.
6. The assembly of claim 1, wherein the mold portion further
includes a passage extending from the second cavity to the outside
of the mold portion, the passage formed to accommodate electrical
conductors of the igniter.
7. The assembly of claim 1, wherein the cover portion includes a
vent passage fluidly connecting the chamber in communication with
the second cavity to the outside of the cover portion.
8. An exothermic welding kit comprising: a mold portion having a
first cavity therein for positioning at least two members adjacent
each other for exothermic welding, the mold portion including an
exterior surface with an annular groove, and a second cavity in
communication with the first cavity and configured for seating a
cartridge containing a weld metal and a first portion of an
igniter; a first cover portion having an exterior surface with an
annular projection configured for sealingly engaging the annular
groove, the first cover portion further configured to cover the
second cavity during the exothermic welding; and a second cover
portion having an exterior surface with an annular projection
configured for sealingly engaging the annular groove, the second
cover portion further including a chamber in communication with the
second cavity and configured for accommodating a filter for
trapping emissions created during the exothermic welding.
9. The kit of claim 8, wherein the mold portion further includes a
passage extending from the second cavity to the outside of the mold
portion, the passage formed to accommodate electrical conductors of
the igniter.
10. The kit of claim 8, wherein the second cover portion includes a
vent passage fluidly connecting the chamber in communication with
the second cavity to the outside of the second cover.
11. An exothermic welding assembly, the assembly configurable for a
smokeless or a non-smokeless welding procedure, the assembly
comprising: a mold portion having a first cavity therein for
positioning at least two members adjacent each other for exothermic
welding, the mold portion including an exterior surface with an
annular groove, and a second cavity in communication with the first
cavity and configured for seating a cartridge containing a weld
metal and a portion of an igniter; a first cover portion having an
exterior surface with an annular projection configured for
sealingly engaging the annular groove and covering the second
cavity during the non-smokeless welding procedure; and a second
cover portion having an exterior surface with an annular projection
configured for sealingly engaging the annular groove during the
smokeless welding procedure, the second cover portion further
including a chamber in communication with the second cavity adapted
to accommodate a filter for trapping emissions created during the
exothermic welding.
12. The assembly of claim 11, further including a preconstructed
cartridge defining a chamber that contains particulate weld metal
prior to ignition.
13. The assembly of claim 12, wherein the cartridge includes a
bottom wall formed of a material that melts with the particulate
weld metal during the exothermic welding.
14. The assembly of claim 12, wherein the cartridge further
includes a filament end of the igniter.
15. The assembly of claim 14, wherein the filament end is formed of
a material that melts with the particulate weld metal during the
exothermic welding.
16. The assembly of claim 11, wherein the mold portion further
includes a passage extending from the second cavity to the outside
of the mold portion, the passage formed to accommodate electrical
conductors of the igniter.
17. The assembly of claim 11, wherein the second cover portion
includes a vent passage fluidly connecting the chamber in
communication with the second cavity to the outside of the second
cover.
18. A mold portion for an exothermic welding assembly, the mold
portion comprising: a first cavity defined therein for positioning
at least two members adjacent each other for exothermic welding; a
second cavity in communication with the first cavity and configured
for seating a cartridge containing a weld metal and a portion of an
igniter; and an exterior surface with an annular groove configured
to separately receive and engage 1) an annular projection of a
first cover portion, the first cover portion cooperative with the
mold portion to cover the second cavity during a non-smokeless
exothermic welding procedure and 2) an annular projection of a
second cover portion, the second cover portion defining a chamber
therein adapted to accommodate a filter for trapping emissions
created during a smokeless exothermic welding procedure.
19. The mold portion of claim 18, further including a passage
extending from the second cavity and in communication with the
outside of the mold portion, the passage formed to accommodate
electrical conductors of the igniter.
Description
BACKGROUND
[0001] The present invention relates to exothermic welding and an
improved assembly, weld metal cartridge and igniter therefor.
[0002] Exothermic welding has been employed in the past as an
effective method of welding two or more members together which may
be copper and/or steel, such as cables to cables, cables to ground
rods, cables to steel surfaces including plates and pipes, cables
to bus bars, cables to rebar and the like. Such exothermic welding
eliminates the need for an outside source of heat or power and
produces a permanent, corrosion resistant weld which cannot loosen
and does not increase electrical resistance.
[0003] In exothermic welding a particulate weld metal is employed
which is a mixture of copper oxide and aluminum which, when
ignited, produces the following chemical reaction:
3Cu.sub.2O+2Al.fwdarw.6Cu+Al.sub.2O.sub.3+heat (4600.degree.
F.)
[0004] To accomplish such welds the members to be welded together
are positioned adjacent to each other utilizing a weld cavity in a
mold formed of a material, such as graphite, which is capable of
withstanding the extremely high temperatures of the exothermic
welding process. Another ignition cavity in the mold contains a
loose particulate weld metal which is to be ignited to initiate the
welding process. A metal disk, which typically is a tin plated
steel, is first positioned in the ignition cavity to prevent the
loose particulate weld metal from flowing into the welding cavity
in which the materials are to be welded together prior to ignition.
The loose particulate weld metal is then poured into the ignition
cavity, and the mold cover is closed. In order to initiate
ignition, a spark generator ignites the loose particulate weld
metal which melts in the ignition cavity to melt the metal disk and
the molten weld metal flows from the ignition cavity into the weld
cavity to weld the members together.
[0005] In another prior exothermic welding procedure as disclosed
for example in U.S. Pat. No. 6,994,244, a weld metal cartridge
comprising a container which contains the weld metal is placed in
the ignition cavity of the mold, and an igniter formed of
electrical conductors is positioned in the weld metal in the
container. When an electrical current is passed through the
conductors, the igniter heats to ignite the weld metal, and the
molten weld metal flows from the ignition cavity into the weld
cavity to weld the members together. In this procedure, the
container may be formed of a metal, such as copper, which also
melts with the weld metal and flows with the molten weld metal to
the weld cavity. The container may also be formed of other metals,
such as steel. However, even though the steel bottom of the
container may achieve a sufficient temperature to melt when the
weld metal is melted, the steel side walls may not, thereby leaving
a residue which must be removed from the ignition cavity before the
mold can be reused to perform another welding procedure.
[0006] In still another prior exothermic welding procedure,
ignition of the loose particulate weld metal in the ignition cavity
is initiated by first igniting a starting powder which ignites
quickly and at a lower ignition temperature than the ignition
temperature of the weld metal. This starting material may be a more
finely ground form of the weld metal and may be located in a
depression in the cover of the mold where it can be ignited by a
spark from a flint igniter. After ignition, the molten starting
material flows through the cover and into the weld metal in the
ignition cavity of the mold to ignite and melt the weld metal in
the ignition cavity.
[0007] Smokeless exothermic welding procedures are also currently
available for exothermic welding in clean room environments. In
such smokeless procedures a filter is employed with the mold to
trap most of the emissions created in the exothermic welding
process while allowing the heated air to escape through the
filter.
[0008] It would be desirable if an exothermic welding mold existed
which was capable of accommodating at least each of these several
exothermic welding procedures as well as others, and which would
avoid the need for maintaining an inventory of different molds in
order to enjoy the specific advantages of each procedure.
[0009] It would also be desirable if the mold was capable not only
of accommodating the performance of each of these exothermic
welding procedures, but could also accommodate the smokeless
exothermic welding procedures discussed above.
SUMMARY
[0010] In one principal aspect of the present invention, an
exothermic welding assembly comprises a mold formed of a material
which withstands exothermic welding temperatures and which has an
elongate axis. The mold includes a first portion having a first
cavity therein for positioning at least two members adjacent each
other which are to be exothermically welded together, and a second
portion comprising a mold cover. A second cavity is present in the
mold for containing a weld metal. The second cavity communicates
with the first cavity and has a first vent passage extending
therefrom to the exterior of the mold to vent gases from the second
cavity. A depression is located in the mold cover for containing a
starting material for the initiation of the reaction of the weld
metal. The depression in the mold cover opens to the top of the
mold cover, and a second passage extends between the depression and
the second cavity in the mold to communicate the starting material
when ignited with the weld metal in the second cavity. A third
passage is also associated with the mold and which extends at a
substantial angle to the elongate axis from a side of the mold and
toward the elongate axis of the mold and the depression.
[0011] In still another principal aspect of the present invention,
in the assembly the third passage extends through the cover and
from the side of the mold into the depression, and the third
passage is constructed and arranged to receive an electrical
igniter and contain it in the third passage so that the igniter can
extend from outside of the mold into the depression.
[0012] In another principal aspect of the present invention, in the
assembly the third passage extends along the top of the cover and
from the side of the mold toward the depression, and the third
passage is constructed and arranged to receive an electrical
igniter and contain it in the third passage so that the igniter can
extend from a side of the mold into the depression.
[0013] In still another principal aspect of the present invention,
the assembly includes a fourth passage which extends at a
substantial angle to the elongate axis from a side of the mold and
toward the elongate axis between the first portion of the mold and
the cover and from the side of the mold and into the second cavity,
and the fourth passage is also constructed and arranged to receive
an electrical igniter and contain it in the fourth passage so that
the igniter can extend from outside of the mold into the second
cavity and the weld metal therein.
[0014] In still another principal aspect of the present invention,
the assembly includes a container in the second cavity in the mold
which contains the weld metal, and an electrical igniter has one
end positioned in the container and in the weld metal therein, and
the other end extends laterally from the container and through the
fourth passage to the outside of the mold.
[0015] In still another principal aspect of the present invention,
the container includes a cover on the container, and the igniter
extends laterally from the container and from beneath the
cover.
[0016] In still another principal aspect of the present invention,
the assembly includes a filter in the mold between the second
cavity and the first vent passage.
[0017] In still another principal aspect of the present invention,
a weld metal cartridge for exothermic welding comprises a container
having a top, a side wall and a bottom with the side wall and
bottom defining a chamber therein. A particulate weld metal is in
the chamber, and a cover covers the top and retains the particulate
weld metal in the chamber and the said side wall of the container
is positioned relative to the particulate weld metal and is formed
of a material so that the side wall melts with the particulate weld
metal during the welding procedure. A plate of material is located
adjacent the bottom which is formed of a material which melts at a
higher temperature than the material of the side wall.
[0018] In still another principal aspect of the present invention,
the material of the side wall comprises copper and/or the plate
comprises steel, and the plate may be a disk which covers a
substantial area of the bottom.
[0019] In still another principal aspect of the present invention,
the container includes a bottom wall and the disk is fixed to the
bottom wall.
[0020] In still another principal aspect of the present invention,
an electrically conductive igniter has one end thereof in the
chamber of the container beneath the cover and adjacent the weld
metal, and an opposite end of the igniter extends from the
container and from beneath the cover, whereby the end of the
igniter in the container ignites the weld metal upon passage of an
electrical current through the igniter.
[0021] In still another principal aspect of the present invention,
an igniter for igniting a particulate exothermic weld metal
comprises a pair of flat, longitudinally extending electrical
conductor strips, and a sheet of insulation is laminated between
the electrical conductor strips to insulate the electrically
conductive strips from each other. An ignition element comprising a
filament is located adjacent one end of the electrical conductor
strips and electrically connected to the strips, and the filament
is formed of a material which heats substantially when electricity
is passed therethrough to a temperature sufficient to ignite the
exothermic weld metal. The other end of the electrical conductor
strips is adapted to be coupled to a source of electrical power
sufficient to cause the filament to heat to ignite the particulate
exothermic weld metal.
[0022] In still another principal aspect of the present invention,
the filament material is tungsten and/or the insulation is an
aromatic polyamide.
[0023] In still another principal aspect of the present invention,
at least one positioning tab is located adjacent the one end of one
of the strips for positioning the filament prior to ignition of the
particulate exothermic weld metal, and the positioning tab may be
constructed and arranged to couple the igniter to the top of a
container for containing the particulate exothermic weld metal.
[0024] In still another principal aspect of the present invention,
at least two positioning tabs are spaced from each other on one end
of one of the strips and they may be constructed and arranged to
couple the igniter to the top of a container for containing the
particulate exothermic weld metal.
[0025] In still another principal aspect of the present invention,
one of the electrical conductor strips is narrower in width than
the other.
[0026] These and other objects, features and advantages of the
present invention will be more clearly understood through a
consideration of the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In the course of this description reference will be
frequently made to the attached drawings in which:
[0028] FIG. 1 is an overall perspective, exploded view of a
preferred embodiment of exothermic welding mold assembly of the
present invention;
[0029] FIG. 2A is a plan view of the mold assembly as substantially
shown in FIG. 1;
[0030] FIG. 2B is a cross sectioned elevation view of the mold
assembly shown in FIG. 2A and as viewed substantially along line
2B-2B of FIG. 2A, and in which a welding procedure is shown in
which a starting material is ignited by the spark of a flint
igniter;
[0031] FIG. 3A is a plan view of the mold assembly as substantially
shown in FIG. 1;
[0032] FIG. 3B is a side elevational view of the cover of the mold
assembly as viewed substantially along line 3B-3B of FIG. 3A;
[0033] FIG. 3C is a cross sectioned elevation view of the mold
assembly shown in FIG. 3A and as viewed substantially along line
3C-3C of FIG. 3A, and in which a welding procedure is shown in
which a starting material is ignited by an electrical igniter;
[0034] FIG. 4A is a plan view of the mold assembly as substantially
shown in FIG. 1;
[0035] FIG. 4B is a cross sectioned elevation view of the mold
assembly as viewed substantially along line 4B-4B of FIG. 4A, and
in which a welding procedure is shown in which loose weld metal is
ignited in the ignition cavity by an electrical igniter
therein;
[0036] FIG. 5A is a plan view of the mold assembly as substantially
shown in FIG. 1;
[0037] FIG. 5B is a cross sectioned elevation view of the mold
assembly as viewed substantially along line 5B-5B of FIG. 5A, and
in which a welding procedure is shown in which the weld metal is in
a cartridge placed in the ignition cavity and which is ignited by
an electrical igniter in the cartridge;
[0038] FIG. 6A is a plan view of the mold assembly as substantially
shown in FIG. 1;
[0039] FIG. 6B is a cross sectioned elevation view of the mold
assembly as viewed substantially along line 6B-6B of FIG. 6A, and
in which a smokeless welding procedure employing the cartridge as
shown in FIG. 5 is employed;
[0040] FIG. 7A is a plan view of a second preferred embodiment of
exothermic welding mold assembly of the present invention;
[0041] FIG. 7B is a side elevation view of the cover of the mold
assembly as viewed substantially along line 7B-7B of FIG. 7 A;
[0042] FIG. 7C is a cross sectioned elevation view of the mold
assembly shown in FIG. 7A as viewed substantially along line 7C-7C
of FIG. 7A;
[0043] FIG. 8 is a cross sectioned enlarged elevation view of the
cartridge container and igniter substantially as shown in FIGS. 5B
and 6B;
[0044] FIG. 9 is an enlarged detailed overall perspective view of
the electrical igniter substantially as shown in the preceding
figures; and
[0045] FIG. 10 is an overall perspective view of a preferred
embodiment of electrical power source for firing the electrical
igniter to initiate the exothermic reaction.
DETAILED DESCRIPTION
[0046] With particular reference to FIG. 1, a preferred embodiment
of exothermic welding assembly of the invention and for practicing
the welding procedures of the invention comprises a mold M formed
of a suitable material, such as graphite; for withstanding the
extremely high temperatures of the exothermic welding process. The
mold M as typically employed in exothermic welding is comprised of
two mold halves 10 and 12 and a cover 14 as shown in FIG. 1. Mold
half 10 includes one half of a weld cavity 16 which, for example as
shown in FIG. 1, receives members, such as cables 18, 19, 20 and
21, to position the cables in a closely adjacent relationship to
each other to be exothermically welded together in the weld cavity
16. Although the members 18-21 as shown in the drawings as the
members to be welded together are cables, the members may be
plates, pipes, rebar, etc., or combinations thereof and the weld
cavity 16 may open to a face of the mold M to accommodate such
other shapes for example as shown in U.S. Pat. No. 6,382,496 which
is incorporated herein in its entirety by reference. And although
four cables 18, 19, 20 and 21 are shown as being welded together it
will be understood that the number of cables may be fewer of
greater than four.
[0047] Mold half 10 also includes a second vertically extending one
half ignition cavity 22 which opens to the top of mold half 10 as
seen in FIG. 1. Cavities 16 and 22 are connected by a passage 24
which permits the molten exothermic weld metal to flow between the
ignition cavity 22 to the weld cavity 16 to weld the members 18,
19, 20 and 21 together in the welding process.
[0048] Although not fully shown in the drawings, the side of the
other mold half 12 which faces mold half 10 includes the other
complementary half of weld cavity 16, ignition cavity 22 and
passage 24 to complete the cavities and passage when the mold
halves are assembled together.
[0049] In addition, a pair of guide recesses 26 extend from the
face of the mold half 10 which faces mold half 12 to receive
complementary guide pins (not shown) on mold half 12 to assure
accurate alignment of the mold halves when they are assembled
together. Although the recesses 26 are shown extending from the
face of mold half 10 into the mold half, the location of the
recesses can be reversed without departing from the invention, i.e.
the recesses 26 may be positioned on mold half 12 and pins on mold
half 10.
[0050] The mold M is completed by the cover 14 which covers the
ignition cavity 22 when the exothermic reaction is to be initiated.
The cover 14 is preferably hinged to mold half 10 by a hinge 27 as
shown in FIG. 1. The cover also includes a vent passage 28 which
extends from one side of the cover 14 to over the ignition cavity
22 to permit venting of the gases and heat generated during the
exothermic welding procedure.
[0051] As in typical exothermic welding molds, the two mold halves
10 and 12 are held together by a suitable handle clamp (not shown).
Accordingly, recesses 29 are shown on mold in FIG. 1 to accommodate
the handle clamp. A suitable clamping arrangement is shown in the
aforementioned U.S. Pat. No. 6,382,496.
[0052] The mold halves 10 and 12 may also include an annular
projection 30 which is adapted to fit into a complimentary annular
groove 32 in the mold cover 14 to more securely hold the mold
halves together during the welding procedure. It will be
appreciated that the location of the projection 30 and groove 32
may be reversed if desired, i.e. the projection 30 may be on the
cover 14 and the groove 32 on the mold halves 10 and 12.
[0053] Thus far, the mold which has been described is essentially
conventional in the exothermic welding art.
[0054] In the preferred embodiment of the present invention the
exothermic welding mold M is constructed to be readily compatible
with anyone of a number of different welding procedures. Thus, the
number of molds that need to be kept in inventory to accomplish
individual and different welding procedures is substantially
reduced if not eliminated altogether and only a single mold
construction need be employed.
[0055] The construction and use of the mold assembly of the
invention for one such exothermic welding procedure is shown in
FIGS. 2A and 2B. In this procedure, a fine particulate starting
material 34 is placed in a depression 36 in the top of the mold
cover 14 as seen in FIGS. 2A and 2B. The depression 36 is formed in
the cover 14 of the mold and opens to the top of the cover so that
it may be accessed from the top of the cover for placement of the
starting material 34 therein, and to permit ignition of the
starting material by a spark from a flint igniter. The starting
material 34 may simply comprise the weld metal which is to
ultimately form the weld, but in a more finely divided form so that
it ignites quicker and at a lower temperature than the weld
metal.
[0056] As shown in FIGS. 2A and 2B, the depression 36 may take the
form of an elongate groove 38 which is formed in the cover 14 and
which preferably extends and opens to one side of the cover, but
does not extend all the way across the cover to the other side of
the cover as seen in FIGS. 2A and 2B. The depression 36 may be
further defined by a projection 40 which extends from one of the
sides of the groove 38, but stops before reaching the other side of
the groove to form a space 41. This construction including the
space 41 permits any debris which might be left in the depression
36 following the completion of the weld procedure to be easily
removed from the depression by a brush or the like. Space 41 also
serves another function in one of the other weld procedures to be
later described.
[0057] The depression 36 also contains a substantially vertical
passage 42 extending between the depression 36 and a chamber 44 in
the cover 14, and the chamber 44 communicates directly with the
ignition cavity 22. The passage 42 permits the molten starting
material 34 after it has been ignited to flow into the ignition
cavity 22 as seen in FIG. 2B and ignite the particulate weld metal
46 in the ignition cavity. The weld metal 46 prior to ignition is
held in the ignition cavity 22 and prevented from passing through
passage 24 by a tin plated steel disk 48 or disk of other suitable
material which may be consumed by the molten weld metal and become
part of the weld.
[0058] In order to perform the welding procedure using the mold
assembly as shown in FIGS. 2A-2B, the cables 18, 19, 20 and 21
which are to be welded together in the procedure are placed in one
half of the weld cavity 16 of either mold half 10 or 12 and the
mold halves are clamped together to form the bottom portion of the
mold M. When the mold halves 10 and 12 are clamped together, they
define the complete ignition cavity 22 and weld cavity 16, and the
cables are held, in position in readiness to be welded together in
the weld cavity. Now that the ignition cavity 22 is formed and
complete, the disk 48 is placed in the bottom of the ignition
cavity 22 and the ignition cavity is filled to the desired level
with the particulate weld metal 46. The cover 14 of the mold is
then closed and the starting material 34 is placed in the
depression 36.
[0059] In order to initiate the exothermic welding procedure shown
in FIGS. 2A and 2B, a flint igniter 50 is positioned relative to
the starting material 34 in the depression 36 of the mold cover 14
and is activated to generate a spark to ignite the starting
material 34. When the starting material is ignited, it melts and
the molten material passes through passage 42 into the weld metal
46 in the ignition cavity 22. This molten starting material 34 then
ignites the weld metal 46 which generates substantial heat on
ignition and it melts the steel disk 48. This will result in the
molten weld metal 46 and melted disk 48 to pass through passage 24
into the weld cavity 16 to weld the cables 18, 19, 21 and 21
together.
[0060] Another welding procedure which may be performed by the mold
assembly of the present invention is shown in FIGS. 3A-3C. In this
procedure, the starting material 34 is also positioned in the
depression 36 as previously described. However, in this procedure,
ignition is accomplished by an electrical igniter.
[0061] As seen in FIGS. 3A-3C and 9, the electrical igniter 52 is
formed by laminating a flat sheet of insulation 54 between two,
flat longitudinally extending electrical conductor strips 56 and
58. The insulation may for example be an aromatic polymer such as
Nomex which is available from E. I DuPont de Nemours & Co. The
conductor strips 56 and 58 are preferably formed of a metal which
is a good electrical conductor, such as copper. The upper strip 56
is somewhat narrower in width and is shorter than the bottom strip
58, as best seen in FIG. 9, and for a reason to be described to
follow. The upper strip 56 is also shorter than the lower strip 58
which permits the upper strip to terminate in a projection 60 which
is spaced from a similar projection 62 formed on the lower strip 58
further toward the end of the igniter. A wire filament 64 is held
by the spaced projections 60 and 62 and extends between them. The
filament 64 is formed of a material which gets sufficiently hot
when an electrical current is passed through the filament to ignite
the starter material 34. The filament material may for example be
stainless steel or tungsten.
[0062] A tab 66 is also preferably formed on the end of the lower
conductor strip 58. The tab 66 in addition to other functions as
will be described in other welding procedures to follow, serves to
act as a positioning element by engaging the projection 40 in the
groove 38 as seen in FIG. 3C to thereby insure that the filament 64
is properly positioned relative to the starting material 34 before
ignition.
[0063] In order to accommodate the electrical igniter 52, passage
68 is formed in the cover 14 as best seen in FIGS. 3A-3C which
extends at a substantial angle to the elongate axis a-a of the mold
M. The passage 68 opens to a side of the mold cover 14 and extends
through the mold cover to the depression 36 in which the starting
material 34 is positioned. The passage 68 preferably takes the
shape of an inverted T as best seen in FIG. 3B having a narrower
portion 69 opening to the top of the mold cover 14 and a wider
portion 70 at the bottom. This permits the wider lower conductive
strip 58 to be positioned in the wider portion 70 of the passage 68
and the narrower upper conductor strip 56 in the narrower portion
69 of the passage. This stabilizes the conductor 52 against both
vertical as well as lateral movement and insures that the filament
64 is always properly positioned in the starter material 34 and not
too far above it to accomplish its ignition function. It will also
be appreciated that in the alternative the conductive strips 56 and
58 and the sheet or strip of insulation 54 may all be of the same
width in which case they will all be positioned in the wider
portion 70 of the passage 68.
[0064] The passage 68 also preferably includes a still wider
portion 71 adjacent its end at and opening to the depression 36.
This still wider portion receives tabs 72 which extend from the
lower wider conductor strip 58 as best seen in FIG. 9 and which
have a principal function to be described later with regard to
still another welding procedure. Positioning of the tabs 72 in the
still wider portion 71 of the passage 68 also assists in the
positioning and holding of the igniter and the filament 64 relative
to the starting material 34, and also permits the use of a single
igniter construction to be used in all of the welding procedures to
be described herein and which are initiated electrically.
[0065] To perform the welding procedure shown in FIGS. 3A-3C, the
initial steps are again taken as described with respect the
procedure shown in FIGS. 2A-2B up to ignition. Once the procedure
is ready for ignition, the right end of the electrical conductor 52
opposite the filament 64 is inserted from the left as viewed in
FIG. 3C into the narrower and wider elongate passages 69 and 70 and
slid horizontally to the right. The projections 60 and 62 and
filament 64 will pass the projection 40 through the space 41, the
tab 66 will come to rest against the projection 40, and the tabs 72
will be positioned in the wider portion 71 of the passage 68 as
seen in FIGS. 3A and 3C. At this point the right end of the
conductor extends from the side of the mold cover 14 to its outside
where it can be coupled to a suitable power source to provide the
electrical current necessary for ignition.
[0066] At this point, the electrical igniter 52 and its filament 64
have been properly positioned to commence the welding procedure
shown in FIGS. 3A-3C and the igniter is held in this position in
the passage 68. Electrical power is then transmitted through the
conductors 56 and 58 to heat the filament 64 and ignite the
starting material 34. From there on, the procedure is identical to
the procedure described with respect to FIGS. 2A-2B.
[0067] Still another welding procedure which may be performed by
the mold assembly of the present invention is shown in FIGS.
4A-4B.
[0068] As in the previous procedures, the particulate weld metal 46
is contained in the ignition cavity 22. However, in this welding
procedure the electrical igniter 52 as previously described with
respect to FIGS. 3A-3C and 9 extends through an elongate passage 73
between the top of the lower mold half 10 of the mold M and the
bottom of the cover 14 between the ignition cavity 22 and through
the side of the mold and at a substantial angle to the elongate
axis a-a of the mold M as seen in FIG. 4B.
[0069] To perform this welding procedure as shown in FIG. 4A-4B,
the initial steps are identical to those previously described,
except that the starting material in the depression 36 and the
placement of the electrical igniter 52 through the passage 68 are
eliminated. Instead the electrical igniter 52 is positioned in the
passage 73 so that its forward end with the filament 64 is located
directly in the weld metal 46 and the other end of the electrical
igniter 52 extends to outside of the mold M where it may be coupled
to a suitable electrical energy source to energize the igniter 52.
In this procedure the portions of the igniter 52 which are in the
ignition cavity 22 also melt when the weld metal 46 melts, and
together with the molten weld metal flow through passage 24 and
into the weld cavity 16 to become part of the weld.
[0070] Still another welding procedure which the mold assembly of
the present invention is capable of accommodating is shown in FIGS.
5A-5B. In this welding procedure, instead of positioning the
particulate weld metal 46 and igniter 52 freely in the ignition
cavity 22 as in the procedure shown in FIGS. 4A-4B, the weld metal
and filament end of the igniter are contained in a preconstructed
cartridge 74 having side walls 76 and a bottom wall 78 which define
a container 79 having a chamber 80 therein. The container 79 is
preferably constructed and sized to fit into the ignition cavity 22
as shown in FIG. 5B and the weld metal 46 and filament end of the
igniter 52 are contained in its chamber 80. The container side
walls 76 and bottom wall 78 are preferably formed of a material
which melts with the weld metal 46 and therefore is removed from
the ignition cavity 22 and becomes part of the weld in the weld
cavity 16 leaving little if any residue in the ignition cavity 22
after the welding procedure is completed. Such meltable material
may for example be copper metal. As previously mentioned; the
filament end of the igniter 52 which is in the container also melts
with the molten weld metal and becomes part of the weld in the weld
cavity 16.
[0071] To assemble the cartridge 74 the chamber 80 of the cartridge
is preferably substantially filled with the particulate weld metal
46. The electrical igniter 52 is then positioned on the top of the
container 79 with the filament 64 in the particulate weld metal 46,
and the igniter is fixed to a laterally extending rim 81 which
preferably extends annularly around the top of the container 79 by
crimping the tab 66 at the end of the lower conductor strip 56
under the rim 81 as seen in FIGS. 5B and 8. The electrical igniter
52 also preferably includes tabs 72 as previously discussed which
are spaced from the tab 66 and also project from the lower
conductor strip 58 as best seen in FIG. 9. Tabs 72 are also
positioned to be inserted under the container rim 81 at the
opposite side of the container 79 from the tab 66. Thus, the tabs
66 and 72 firmly hold the electrical igniter 52 in position on the
container 79 and so that the projections 60 and 62 and igniter
filament 64 are located in the weld metal 46. In order to complete
the cartridge 74, the container 79 and its chamber 80 are covered
with a cover 84 to prevent loss of the weld metal 46 during
shipping and handling. The cover 84 may comprise a suitable film,
such as aluminum foil, polymer or the like, which will also be
consumed during the welding procedure and passed with the molten
weld metal 46 and container side walls 76 and bottom wall 78 into
the weld cavity 16 to become part of the weld.
[0072] The welding procedure as shown in FIGS. 5A-5B is essentially
identical to that described with respect to FIGS. 4A-4B, except
that the weld metal 46 and electrical igniter 52 are contained
within the preconstructed cartridge 74 and its container 80.
Accordingly, all that is needed to perform the welding procedure of
FIGS. 5A-5B after the cables 18, 19, 21 and 21 are positioned in
the weld cavity 16 and the mold halves 10 and 12 are clamped
together, is to place the cartridge 74 into the ignition cavity 22
so that the portion of the igniter 52 outside of the container 80
extends from the ignition cavity 22 through the passage 73 to the
outside of the mold M. The mold cover 14 is then closed, the end of
the igniter 52 is coupled to a suitable source of electrical energy
and the igniter 52 is energized.
[0073] Although the container 79 and its side wall 76 and bottom
wall 78 as seen in FIGS. 5A-5B and 8 may be formed of a material
such as a copper metal which readily melts and is consumed during
the ignition of the weld metal 46 to become part of the weld in the
weld cavity 16, it is preferred that a steel plate such as a disk
48 also be positioned adjacent the bottom of the container 79 as
seen in FIGS. 5B and 8. The reason that the additional steel disk
48 is preferred is that it slows the initial discharge of the weld
metal 46 through passage 24 at the beginning of ignition because it
has a higher melt temperature than the copper metal in the
container walls and bottom. This permits the temperature of the
molten weld metal to be higher and produce better slag
(Al.sub.2O.sub.3) separation when it finally melts the disk 48 and
is discharged into the passage 24 and weld cavity 16. This results
in a more homogenous mix of the various materials of the container
79, igniter 52 and weld metal 46 in the final weld and improves the
quality of the weld in the weld cavity 16. Although the disk 48 is
shown fixed to the bottom 78 of the container 79, in the
alternative it may itself form the bottom of the container 79, or
it may be separate from the bottom 78 of the container 79 and be
placed in the bottom of the ignition cavity 22 followed by the
cartridge 74.
[0074] The welding procedure shown in FIGS. 6A-6B is essentially
identical to the procedures described for FIGS. 5A and 5B. The only
difference is. that the procedure shown in FIGS. 6A and 6B is a
smokeless procedure in which the mold cover 14 accommodates a
filter F in the chamber 44 in the mold cover 14 between the
ignition cavity 22 and the vent passage 28 in the mold cover 14 as
best seen in FIG. 6B. The filter F traps most of the emissions
created in the exothermic welding process while allowing the heated
air to escape through the filter.
[0075] Although the smokeless procedure shown in FIGS. 6A-6B is
shown as employed with the procedure shown in FIGS. 5A-5B utilizing
the cartridge 74, it will be appreciated that it also may be
employed with the procedure shown and described in FIGS. 4A-4B
where the weld metal 46 is positioned loosely in the ignition
cavity 22 and not in a cartridge.
[0076] The construction and welding procedure and mold assembly
shown in FIGS. 7A-7C are substantially the same as that described
with respect to FIGS. 2A-2B. In both procedures, the starting
material 34 is positioned in the depression 36 in the mold cover
14. However, unlike FIGS. 2A-2B in which the igniter 52 is
positioned in the passage 68 which is formed in the mold cover 14,
the igniter 52 in FIGS. 7A-7C extends through a passage 85 formed
in the bottom of a block 86 which is fastened to the top surface 87
of the mold cover 14 by suitable fasteners 88. The block 86 may be
formed of any suitable material that is capable of withstanding the
heat to which it may be exposed during the welding procedure, such
as anodized aluminum. The block 88 firmly holds the igniter against
the top surface 87 of the mold and against lateral or vertical
movement and it positions the filament 64 in the mold depression 36
and starter material 34. The passage and block arrangement shown in
FIG. 7A-7C have the advantage of being somewhat simpler to form the
passage through which the igniter 52 is to extend.
[0077] A suitable power supply 90 is shown in FIG. 10 which
generally comprises a housing 91 with a battery (not shown)
therein. An electrical connector 92 extends from the housing 91
which is electrically connected to the battery and has an external
coupling 94 having a socket 95 which receives the distal end of the
electrical igniter 52 to transmit electrical energy to the igniter
and its filament 64. To energize the igniter 52 to ignite either
the starting material 34 or the weld metal 46, a switch 96 is
provided to turn on and off the electrical power to the socket
95.
[0078] Upon consideration of the foregoing description of the
invention, it will be appreciated that the exothermic welding
assembly of the present invention has the capability of
accommodating multiple different exothermic welding procedures
through the use of a single mold assembly, thus greatly simplifying
the exothermic welding procedure and reducing the need for
inventory of multiple molds unique to the various exothermic
welding procedures. It will also be appreciated that in the welding
procedures in which the cartridge 74 is provided, the handling of
the particulate weld metal and igniter is facilitated and the
proper placement of the igniter is assured together with efficient
and consistent functioning of the welding procedures. Moreover, the
cartridge 74, although capable of being consumed and cleared from
the ignition cavity during the exothermic welding process with
little or no residue or debris, also may be formed or used in
conjunction with the disk 48 improve the quality of the final
weld.
[0079] It will also be understood that the preferred embodiments of
the present invention which have been described are merely
illustrative of the principles of the invention. Numerous
modifications may be made by those skilled in the art without
departing from the true spirit and scope of the invention.
[0080] Various features and advantages of the invention are set
forth in the following claims.
* * * * *