Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Title: Welding Torch Apparatus
Field of the Invention
This invention relates in general to arc welding equipment and more
particularly to
arc welding torch cleaning devices.
Background of the Invention
Metal inert gas (MIG) and metal active gas (MAG) welding equipment introduces
a welding wire and a shield gas through a passageway running through the
welding torch.
The welding wire and the shield gas share the same passageway. The welding
wire exits at
a tip at the gas nozzle whereas the shield gas exits via a gas diffuser inside
the gas nozzle.
During welding the shield gas exiting from the gas nozzle provides a shroud of
gas around
the welding pool area ensuring the integrity and quality of the weld.
The arc welding process creates weld material spatter at the welding tip which
often
adheres to the weld tip and/or the inside of the gas nozzle eventually
clogging the torch and
leading to a breakdown of weld integrity and quality. This problem has plagued
the arc
welding process since its inception and has become particularly acute in high
production
robotic welding operations where any down time is critical.
In order to overcome this clogging problem a number of methods and devices
have
been used or described to clean the welding tip and gas nozzle. One method is
to
mechanically remove the welding spatter that has accumulated on the welding
tip and gas
nozzle by abrading or brushing the surfaces affected. Another method is to
periodically dip
the gas nozzle with the welding tip into a container of oil coating the gas
nozzle and welding
tip surfaces in order to minimize the adhesion of the spatter on these parts
of the welding
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torch.
Another method for preventing the build up of spatter on the gas nozzle and
welding
tip is described in US Patent No. 4,609,804 dated September 2, 1986 by Kishi
et al. entitled
Arc Welding Apparatus, in which is described an automated means for
introducing oil mist
into the welding nozzle and tip area via the existing passageway and gas
diffuser which
transmit the shield gas and welding wire to the gas diffuser and welding torch
tip
respectively. This method of preventing spatter build up includes momentarily
introducing
pressurized air through the passageway and into the gas diffuser and then
introducing
pressurized air with an oil mist entrained through the passageway and into the
gas diffuser
to coat the welding tip and the interior of the gas nozzle. The oil mist is
turned off, the
shielding gas turned on and welding is continued.
The drawback with this method is that the welding wire is in intimate contact
with the
oil in the oil mist air mixture as it travels through the passageway. The oil
mist which is
introduced through the passageway can adhere to the welding wire and be
dragged through
to the welding tip and onto the work piece being welded. This can lead to
welding
imperfections and may also lead to blockage and gumming up of the passageway.
Accordingly there is a need for an apparatus and method which overcomes the
above
mentioned problems in existing devices and methods and provides an effective,
automated
means of keeping the welding torch and welding tip clean without sacrificing
weld quality.
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Summarv of the invention
In accordance with one aspect of the invention: a welding torch apparatus for
use with
conventional arc welding torches having, a gas nozzle with an interior and a
longitudinal
axis, a first passageway for supplying of both a welding wire to a tip, and
gas mixtures to a
gas diffuser, the welding torch apparatus comprises a gas injection means for
selectively
introducing into the interior of the gas nozzle, gas mixtures which by-pass
the first
passageway, so that contact is avoided between gas mixtures passing through
the gas
injection means, and gas mixtures and welding wire passing through the first
passageway,
until the gas mixtures and welding wire enter the interior of the gas nozzle
and wherein only
gas mixtures passing through the gas injection means include oil additions for
coating with
oil an interior surface of said gas nozzle as well as said gas diffuser and
tip thereby
minimizing weld spatter buildup on said interior surface, gas diffuser, tip,
and also
minimizing oil contamination of said weld wire.
Preferably the gas injection means comprises a second passageway for
selectively
introducing into the interior of the gas nozzle gas mixtures through the
second passageway
which by-passes the first passageway, so that contact is avoided between the
gas mixtures
passing through the second passageway, and gas mixtures and welding wire
passing through
the first passageway, until the gas mixtures and welding wire enter the
interior of the gas
nozzle.
Preferably the gas injection means comprises a longitudinally extending
mounting
tube securely attached to a gooseneck. The mounting tube has longitudinal
channels defined
in an outer diameter for receiving gas mixtures and communicating gas mixtures
to the
interior of the gas nozzle. The welding torch apparatus additionally comprises
an injector
collar securely mounted on the outer diameter of the mounting tube, the
injector collar
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having a gas receiving means for receiving gas mixtures and communicating gas
mixtures
to the mounting tube channels.
Preferably the gas diffuser comprises gas discharge apertures disposed at an
acute
angle less than 90 degrees relative to the longitudinal axis such that the
flow of gas mixtures
is directed toward the tip.
Preferably the gas discharge apertures are disposed at an acute angle between
60 and
30 degrees relative to the longitudinal axis such that the flow of gas
mixtures is directed
toward the tip.
Preferably the gas mixtures passing through the gas injection means are
selected from
the group comprising; air, air with an entrained oil mist, argon, argon with
an entrained oil
mist, nitrogen, nitrogen with an entrained oil mist, or a mixture thereof, and
gas mixtures
passing through the first passageway are selected from the group comprising;
shield gases,
air, nitrogen, argon or a mixture thereof.
In accordance with another aspect of the present invention: a welding torch
cleaning
apparatus for use with conventional arc welding equipment having a torch, a
gooseneck, a
nozzle, a first passageway for supplying of both a welding wire to a tip and
gas mixtures to
a gas diffuser. The welding torch cleaning apparatus comprises compressed gas
sources
containing gas mixtures. A gas injection means for selectively introducing
into the gas
nozzle gas mixtures which by-pass the first passageway, so that contact is
avoided between
the gas mixtures flowing through the gas injection means and gas mixtures and
welding wire
passing through the first passageway, until the gas mixtures and welding wire
enter the
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interior of the gas nozzle, and wherein only gas mixtures passing through the
gas injection
means include oil additions for coating with oil an interior surface of said
gas nozzle as well
as said gas diffuser and tip thereby minimizing weld spatter buildup on said
interior surface,
gas diffuser, tip, and also minimizing oil contamination of said weld wire. It
additionally
comprises a gas distribution means for selectively communicating gas mixtures
from gas
sources to the gas injection means, and from gas sources to the first
passageway, wherein
torch cleaning is accomplished by supplying gas mixtures to the gas injection
means and to
the first passageway in a pre-selected cleaning cycle.
Preferably the gas distribution means comprises gas pipes connected to the gas
sources and to the first passageway and the gas injection means. The gas pipes
interposed
by gas valves for controllably and selectively communicating gas mixtures from
gas sources
to the gas injection means and from gas sources to the first passageway.
Preferably the gas distribution means further comprises a control means for
controlling the opening and closing of the gas valves according to the pre-
selected cleaning
cycle.
Preferably the control means further comprises a programable electronic
controller
for opening and closing the gas valves according to the pre-selected cleaning
cycle.
In accordance with another aspect of the present invention: a method of
operating an
arc welder having an arc welding torch, a supply of gas mixtures including a
supply of air
with and without an entrained oil mist, a gooseneck, a gas nozzle, and a first
passageway for
supplying both a welding wire to a tip, and supplying gas mixtures to a gas
diffuser. The
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method of operating an arc welder comprises the steps of:
a) Arc welding in a conventional manner with gas mixtures and welding wire
supplied through the first passageway;
b) terminating arc welding;
c) c) supplying gas mixtures via a gas injection means, the gas injection
means
selectively introduces into the interior of the gas nozzle gas mixtures which
by-pass the first passageway, so that contact is avoided between gas mixtures
passing through the gas injection means, and gas mixtures and welding wire
passing through the first passageway, until the gas mixtures and welding wire
enter the interior of the gas nozzle and wherein only gas mixtures passing
through the gas injection means include oil additions thereby coating with oil
an interior surface of said gas nozzle as well as said gas diffuser and tip
thereby minimizing weld spatter, buildup on said interior surface, gas
diffuser
and tip.
d) terminating supply of air with an entrained oil mist; and
e) repeating steps (a) to (e).
Preferably the method of operating an arc welder is modified wherein step (c),
is
substituted with the following step:
c) simultaneously supplying gas mixtures through the first passageway and
supplying gas mixtures via a gas injection means, the gas injection means
selectively
introduces into the interior of the gas nozzle gas mixtures which by-pass the
first
passageway, so that contact is avoided between gas mixtures passing through
the gas
injection means, and gas mixtures and welding wire passing through the first
passageway in
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order to expel excess oil and spatter on gas diffuser, tip and interior
surface of said gas
nozzle; until the gas mixtures and welding wire enter the interior of the gas
nozzle and
wherein only gas mixtures passing through the gas injection means contain oil
additions.
Preferably the method of operating an arc welder has the following additional
steps
prior to step (e):
d') supplying compressed air via the first passageway;
d") terminating supply of compressed air.
In accordance with another aspect of the present invention: a gas diffuser for
use with
conventional arc welding torches having, a gas nozzle with a longitudinal
axis, a first
passageway for supplying of both a welding wire to a tip, and gas mixtures
through the gas
diffuser. The gas diffuser comprises gas discharge apertures disposed at an
acute angle less
than 90 degrees relative to the longitudinal axis such that the flow of gas
mixtures is directed
toward the tip.
Brief Description of the Drawings
The invention will now be described by way of example only, with references to
the
following drawings in which:
Figure 1 is a schematic perspective exploded view of the welding torch
apparatus
particularly showing the gas injection means.
Figure 2A is an exploded schematic side cross sectional view of the welding
torch
apparatus.
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Figure 2B is a schematic transverse cross sectional view taken through A-A of
Figure
2A.
Figure 2C is a schematic transverse cross sectional view taken through B-B of
Figure
2A.
Figure 3A is a schematic side cross sectional view of the portion circled in
Figure 2A.
Figure 3B is a schematic transverse cross sectional view of the detail shown
in Figure
3A.
Figure 4 is a schematic side cross sectional view of the assembled welding
torch
apparatus showing the path of the welding wire and the shield gas through the
first
passageway.
Figure 5 is a schematic side cross sectional view of the assembled welding
torch
apparatus showing the path of the welding wire and the shield gas through the
first
passageway and the oil mist through the second passageway.
Figure 6 is a schematic piping diagram of gas distribution means showing the
piping
and valving for supply of shield gas and gas mixtures to the welding torch
apparatus.
Figure 7 is a flow diagram showing a preferred method of use of the welding
torch
cleaning apparatus.
Figure 8 is a flow diagram showing another preferred method of use of the
welding
torch cleaning apparatus.
Figure 9 is a flow diagram showing yet another preferred method of use of the
welding torch cleaning apparatus
Detailed Description of the preferred Embodiment
Referring to Figure 1, 2A, 2B, 2C and 3A and 3B, a preferred embodiment of the
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present invention, a welding torch apparatus shown generally a 10, comprises
gooseneck 12,
mounting tube 14, injector collar 16, collet 18, gas diffuser 20, tip 22, and
gas nozzle 24.
Mounting tube 14 extends longitudinally from gooseneck tip 26 and has four
longitudinal channels 28 running part way along the outer diameter 15 of
mounting tube 14.
Outer diameter 15 and inner diameter 17 of mounting tube 14 is threaded for
threadably
mounting of components thereon. Injector collar 16 is threadably mounted onto
outer
diameter 15 of mounting tube 14 making contact with first insulator ring 30.
Second
insulator ring 38 makes surface contact with a front surface 19 of injector
collar 16. Collet
18 is threadably mounted onto outer diameter 15 of mounting tube 14 until
collet 18 makes
contact with second insulator ring 38. Gas diffuser 20 is threaded into inner
diameter 17 of
mounting tube 14 until gas diffuser 20 makes contact with tube end 36. Tip 22
is threaded
into gas diffuser 20. Gas nozzle 24 fits over nozzle insulator 42 and nozzle
insulator 42 then
fits interferingly over the outer diameter of collet ring 40. These components
are known in
the art except for: injector collar 16, modifications made to mounting tube
14; namely the
addition of longitudinal channels 28, and optionally modifications to gas
diffuser 20
described below.
Referring now to Figure 4 as well, which shows first passageway 48 shown in
thick
lines which is the pathway taken by welding wire 46 and shield gas 44 through
the welding
torch apparatus 10. A shield gas is a gas used during the welding operation to
protect the
molten weld pool from exposure to air thereby ensuring good weld quality. Gas
mixtures can
be a shield gas, a single gas, two or more gases, or a gas with an oil
addition such as oil in
the form of an oil mist entrained in a gas, or any combination of the
foregoing. Welding wire
46 is supplied through first passageway 48 and exits at tip end 50. Shield gas
44 is also
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introduced through first passageway 48 exiting through gas discharge apertures
52 located
in gas diffuser 20. It will be recognized by those skilled in the art that
this is the
conventional pathway taken by shield gas 44 and welding wire 46. This
configuration or
variations thereof is found in most conventional MIG or MAG welding torches.
It will be
further appreciated that collar 16, and longitudinal channels 28 are new or
modified
components of a conventional torch and that optionally, gas diffuser 20 is
also modified as
described below for optimum performance.
Referring now to Figure 5 as well, gas injection means shown generally as 27
preferably comprises collar 16 having injector gas inlet shown generally as 32
and annular
collar plenum 34. Injector gas inlet 32 is connected to and communicating with
annular
collar plenum 34 which is connected to and communicating with longitudinal
channels 28.
Longitudinal channels 28 extend to tube end 36. Collar 16 together with
longitudinal
channels 28 create a second passageway 33 for gas mixtures to be supplied into
the interior
53 of gas nozzle 24. Injector gas inlet 32 comprises a hole 39 bored proximate
outer
diameter 35 of collar 16 and a connecting bore 37 connecting hole 39 with
collar plenum 34.
Collar plenum 34 distributes gas mixtures to longitudinal channels 28 thereby
evenly
distributing gas mixtures supplied through second passageway 33 around the
inner surface
51 of gas nozzle 24. An incoming pipe (not shown) is threadably connected to
hole 39 for
supplying gas mixtures to gas inlet 32. It will be recognized by those skilled
in the art that
first passageway 48 and second passageway 33 are independent and separate
passageways
which provide the supply of gas mixtures to the interior 53 of gas nozzle 24.
The gas
mixtures passing through the first and second passageway do not contact each
other until
released into the interior 53 of gas nozzle 24.
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Optionally, the following additional modifications can be made. Gas discharge
apertures 52 in gas diffuser 20 are normally disposed perpendicular to
longitudinal axis 23.
In order to optimize the performance of welding torch apparatus 10, gas
discharge apertures
52 are bored optimally at a 45 degree angle as depicted or at an acute angle
between 30 and
60 degrees relative longitudinal axis 23 thereby aiding the flow of gas
mixtures through and
out of the interior 53 of gas nozzle 24. Additionally to enhance the flow of
gas mixtures
through second passageway 33, an annular relief 41 is machined in collet 18 in
order to
assist in the even distribution of gas mixtures to all of the longitudinal
channels 28.
Referring now to Figure 6, a schematic diagram of gas distribution means shown
generally as 61 showing gas sources generally as 63, and gas pipes 65, the gas
distribution
means 61 comprises supplying air 62, shield gas 44, and oil 64 to welding
torch apparatus
10 in a pre-selected manner. Air 62 is supplied to solenoid valves 68, 70 and
to pressure
regulator 66. Pressurized oil reservoir 72 contains oil 64 which is supplied
to solenoid valve
74 and check valve 76. Air 62 is mixed with oil 64 in needle valve 78 creating
an air with
oil mist gas mixture (hereinafter referred to as oil mist 80) which is
selectively supplied to
gas inlet 32. Shield gas 44 and air 62 can selectively be supplied to first
passageway 48 or
shut off completely. Gas sources 63 may also be any other gases known by
persons skilled
in the welding industry and therefore Oil mist 80 may also be any gas known by
persons
skilled in the welding industry entrained or mixed with an oil mist.
In use, MIG or MAG welding with welding torch apparatus 10 is carried out in
the
conventional manner, briefly described as follows. Welding wire 46 is
continuously
supplied through first passageway 48 until exiting at tip 50. Simultaneously
shield gas 44
is introduced through first passageway 48 exiting through gas discharge
apertures 52 in gas
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diffuser 20 creating a gas shroud within the interior 53 of gas nozzle 24 and
also over the
welding puddle (not shown) thereby protecting and shrouding the weld puddle
during
welding. This is the conventional manner in which MIG or MAG welding is
carried out.
Referring now to Figure 7, following steps 102 to 108 is the preferred method
of
carrying out a pre-selected cleaning cycle. Firstly step 102, arc welding is
carried out in the
conventional manner as described above. Secondly step 104, arc welding is
paused or
terminated for a short period of time. During this pause feeding of weld wire
46 through first
passageway 48 is halted and optionally shield gas 44 is turned off. Welding
torch apparatus
10 is then positioned away from the workpiece that is being welded. In third
step 106, oil
mist 80 is introduced into gas injection means 27 and flows through second
passageway 33.
This expels any built up spatter on tip 22, gas diffuser 20 and interior
surface 51 of gas
nozzle 24 and simultaneously coats tip 22, gas diffuser 20 and the interior
surface 51 of gas
nozzle 24 with oil contained in oil mist 80. Finally, in step 108 oil mist 80
is turned off and
optionally shield gas 44 is turned on. The welding torch is repositioned over
the work piece
and welding wire 46 is fed through first passageway 48 and conventional arc
welding
resumes.
Referring now to Figure 8, third step 106 in Figure 7 is replaced by step 107
wherein,
oil mist 80 is introduced via gas injection means 27 and flows through second
passageway
33. This expels any built up spatter on tip 22, gas diffuser 20 and interior
surface 51 of gas
nozzle 24 and simultaneously coats tip 22, gas diffuser 20 and the interior
surface 51 of gas
nozzle 24 with oil contained in oil mist 80. Simultaneously air is supplied
through first
passageway 48 aiding the removal and expulsion of spatter. Steps 102, 104 and
108 are
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identical to those above.
Referring now to Figure 9, preferably the pre-selected cleaning cycle
comprises the
additional steps following step 108 to those described in Figure 7, of steps
110 and 112. In
step 110, compressed air is introduced through first passageway 48 and exits
at gas discharge
apertures 52 thereby eliminating any excess oil and/or spatter still remaining
on gas diffuser
20, tip 22, and interior surface 51 of gas nozzle 24. Step 112, compressed air
flowing through
first passageway 48 is then turned off and welding torch apparatus 10 is moved
into position
over the workpiece to be welded and the feeding of weld wire 46 through first
passageway
48 is once again initiated and optionally shield gas 44 is turned on providing
it had been shut
off earlier and arc welding continues in the conventional manner.
Oil mist 80 enters gas nozzle 24 through second passageway 33 which avoids
contact
with weld wire 46 which it is fed through first passageway 48. Additionally
supplying
compressed air 62 through first passageway 48 (either simultaneously or
sequentially)
ensures that any excess oil is removed from gas diffuser 20, tip 22, and
interior surface 51
of gas nozzle 24. Gas diffuser 20 having gas discharge apertures 52 angled at
approximately
45 relative to the longitudinal axis 23 also helps the cleaning and removal of
excess oil from
within gas nozzle 24. The possibility of excess oil entering the weld puddle
is minimized
thereby providing for a high quality weld.
Oil 64 in this specification is defined as any substance which when applied to
the
surface of gas nozzle 24 prevents weld spatter buildup. The oil 64 must be
capable of being
transported to nozzle 24 in a carrier gas; such as nitrogen or air, and
preferably be transported
in the form of an oil mist 80. Preferably oil 64 is common petroleum oil,
mineral oil,
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vegetable oil and the like. However it may be any spatter retardant material.
It will be apparent to persons skilled in the art that any commercially
available
welding torch can be modified in a similar manner as described in the
preferred
embodiments. There are many different ways of providing two independent and
separate
passageways into the interior 53 of nozzle 24. The exact physical structure
can be varied
without departing from the spirit of this invention. It is also possible to
use a variety of
different gas mixtures. For example the gas mixture may be an inert gas with
an oil addition
or any variety of welding or other gas mixtures that are commercially
available. The
composition of the oil is not critical and many commercially available oils
can be effectively
used as for example motor oil 10W30. The viscosity of the oil is such to
enable an oil mist
to be mixed with a gas which is known to persons skilled in the art.
It will be apparent to persons skilled in the art, various modifications and
adaptations
of the structure described above are possible without departure from the
spirit of the
invention, the scope of which is defined in the appended claims.
