Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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END ASSEMBLY FOR WELDING DEVICE
FIELD OF THE INVENTION
[0001] The present invention relates to an end assembly for use
in a welding device.
In particular, the present invention relates to end assembly for controlling
the flow of gas
during welding.
BACKGROUND
[0002] Metal Inert Gas (MIG) welding also referred to as "wire-
feed" or Gas Metal Arc
Welding (GMAVV) utilizes heat from an electrical arc to melt a consumable
electrode to
form a weld on a workpiece. A MIG welding system typically includes a power
supply, a
gas supply and an electrode supply connected to a welding device or welding
gun. A
ground cable is used to connect the workpiece to the power supply. The welding
device
generally includes a handle, a gooseneck and an end assembly. The welding
system can
be automatic or semi-automatic and may be manually or robotically controlled.
The
electrode and gas are coupled through a conduit in the handle and the
gooseneck to the
end assembly of the welding device. The electrode extends through the contact
tip of the
end assembly and the gas moves around the contact tip in the nozzle of the end
assembly. When the welding device is activated, the electrode is fed through
the contact
tip toward the workpiece and the gas is directed through the nozzle towards
the
workpiece. When the electrode is placed adjacent to will or in contact with
the workpiece,
the electrode completes an electrical circuit between the power supply and the
workpiece,
allowing current to flow through the electrode to the workpiece. The current
produces an
arc between the electrode and the workpiece. The heat of the arc melts the
electrode and
the workpiece in the region surrounding the arc, creating a weld puddle. The
gas flowing
out the nozzle shields the weld puddle from atmospheric gases and outside
contaminants.
The type of gas used in MIG welding varies depending on many factors. Noble or
inert
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gases such as Argon are often used. However, Carbon Dioxide (CO2) and a
mixture of
gases such as CO2 and Argon are also used. Once the electrode is moved away
from the
workpiece, the electric circuit is broken and the weld puddle cools and
solidifies, forming
a weld.
[0003] There remains a need for an end assembly for a welding
device which allows
for better control of the flow of shielding gas around the weld puddle and
which enhances
cooling of the tip during use.
BRIEF SUMMARY OF THE INVENTION
[0004] The end assembly of the present invention is used with a
welding device for
GMAW. In one embodiment, the end assembly includes a gooseneck, a diffuser
body, a
contact tip and a nozzle. The components of the end assembly are secured
together so
as to share a common axis. The diffuser body features a number of passageways
for
allowing shielding gas to flow into an annular space between the diffuser
body, contact
tip and nozzle. In addition, the diffuser body features passageways extending
toward the
contact tip and communicates with a gas chamber. The gas chamber in turn
provides gas
to one or more passageways in the contact tip. In one embodiment, a plurality
of tip
passageways are arranged parallel to and around the central electrode bore of
the contact
tip. In another embodiment, the central electrode passageway of the tip is
backboard at
the base of the tip to provide clearance for gas flow to a series of
transverse passageways
through the nozzle tip. In both embodiments, the gas flow channels, combined
with the
gas flow around the outside annular surface of the nozzle tip, provide
improved shielding
and cooling of the welding tip.
[0005] Further still, the present invention relates to a contact
tip for a welding device
having a radiused or rounded convex curved first end, and a radiused or
rounded second
end with a center bore extending. The second end of the diffuser body has
buttress
threads with mate with buttress threads of the contact tip. The diffuser body
has a
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radiused or rounded concave surface. When the contact tip is attached to the
diffuser
body, the mating concave and convex surfaces are brought into direct contact,
providing
excellent thermal and electrical conductivity between these components. In the
first
embodiment, the above-described tip gas flow channels are positioned directly
adjacent
to the central electrode bore so as not to interfere with the contact between
the mating
concave and convex surfaces of the contact tip and diffuser body. In the
second
embodiment, the contact tip features an enlarged electrode passageway at the
base of
the tip, with the bore at the entrance end of the contact tip radially inside
the concave and
convex surfaces of the diffuser body and contact tip. In both embodiments the
diffuser
body together with the contact tip form a gas flow chamber at the base of the
contact tip
which serves to distribute shielding gas to the flow passages of the contact
tip.
[0006] The substance and advantages of the present invention will
become apparent
by reference to the following drawings and the description.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0007] Figure 1 is a schematic illustration of a GMAW welding
system of a prior art
design.
[0008] Figure 2 is a longitudinal cross-sectional view of an end
assembly of a prior art
GMAW welding system.
[0009] Figure 3 is a longitudinal cross-sectional view through a
nozzle assembly in
accordance with a first embodiment of the present invention.
[0010] Figure 4 is a perspective view of the gas entrance end of
the diffuser body.
[0011] Figure 5 is a perspective view of the gas exit end of the
diffuser body which
receives the contact tip.
[0012] Figure 6 is a cross-sectional view through the nozzle.
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[0013] Figure 7 is a cross-sectional view of an end assembly in
accordance with a
second embodiment of the present invention.
[0014] Figure 8 is a cross-sectional view similar to Figure 7,
showing gas flow paths
through the end assembly.
[0015] Figure 9 is a cross-sectional view of the end assembly of
Figure 7, shown with
an electrode wire passing through the end assembly.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Figure 1 is a general, schematic representation of MIG
welding system 10. The
welding system 10 includes gas supply 12, electrode supply 14, and electrical
power
supply 16 connected to welding device 18. In general, welding device 18
includes handle
20, gooseneck 22 and end assembly 24. Welding device 18 also includes an
activation
switch which, in one embodiment, is trigger 26 on handle 20. Welding system 10
is used
to perform a welding operation on workpiece 34. It is understood that the
welding system
can be operated similar to welding systems well known in the art.
[0017] Figure 2 shows a design of end assembly 10 in accordance
with a prior art
design having gooseneck 22, diffuser sleeve 28, insert 30, contact tip 32 and
nozzle 36.
Gooseneck 22 has opposed first and second ends 38 and 40, with passageway 42
extending therebetween. First end 38 of the gooseneck 22 is connected to
handle 20 of
welding device 18. Gooseneck 22 includes inner conduit 44 which extends
between ends
38 and 40, and forms passageway 42. Inner conduit 44 is constructed of an
electrically
conductive material. In the example presented, inner conduit 44 is made of
copper. Wire
guide 45 is formed from a wound wire and is a flexible cable having a center
bore for
allowing passage of electrode 48. Gooseneck 22 also includes outer housing 46
or
covering which protects inner conduit 44. Passageway 42 of gooseneck 22 is
sized to
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enable wire guide 45, electrode 48 and gas 50 to move through the passageway
from first
end 38 will.
[0018] Diffuser sleeve 28 has opposed first and second open ends
52 and 54, with
wall 56 therebetween, forming inner cavity 58. First end 52 of diffuser sleeve
28 is
mounted on second end 40 of gooseneck 22. Inner cavity 58 extends between open
first
end 52 and open second end 54. The size and shape of inner cavity 58 of
diffuser sleeve
28 varies depending on the type of gooseneck 22, the size of insert 30, and
the type of
contact tip 32 used. Wall 56 has a least one radially extending passageway 60.
In one
embodiment, wall 56 has a plurality of passageways 60 spaced around the
perimeter of
the wall. Passageways 60 in wall 56 are in fluid communication with gooseneck
passageway 42.
[0019] Contact tip 32 is connected to second end 54 of diffuser
sleeve 28. First end
62 of contact tip 32 extends into inner cavity 58 of diffuser sleeve 28.
Center bore 66 of
contact tip 32 extends along the longitudinal axis of the contact tip. When
contact tip 32
is secured in second end 54 of diffuser sleeve 28, center bore 66 of contact
tip 32 is
coaxial with the longitudinal axis of the diffuser sleeve. In one embodiment,
external
threads 68 are formed adjacent to first end 62 of contact tip 32 which mate
with internal
threads 70 on the interior surface of inner cavity 58 of diffuser sleeve 28.
Threads 68 and
70 are preferably formed as buttress profile threads.
[0020] In the prior art example presented, first end 62 of the
contact tip 32 has a
radiused or rounded convex outer end surface. Second end 64 of contact tip 32
is also
radiused. Nozzle 36 has open second end 76 with gas channel 78 surrounding
contact
tip 32. When nozzle 36 is secured on diffuser sleeve 28, the nozzle extends
outward from
first end 74 along diffuser sleeve 28 toward second end 76 so that wall 56 of
diffuser
sleeve 28 is in gas channel 78 and passageway 42 in wall 28 of diffuser sleeve
20 and
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gas channel 78 of nozzle 36. Nozzle 36 extends along contact tip 32 so that
contact tip
32 is in gas channel 78.
[0021] Insert 30 has a first end 80 and a second end 82 and forms
at least one radial
passageway 88. Passageways 88 are in fluid communication with gooseneck
passageway 42 and sleeve passageway 60. Shielding gas flowing into gooseneck
22
escapes into the radial gap situated between tip 32 and nozzle 36 to provide
shielding
gas flow to the weld site.
[0022] In the prior art example presented, the inner surface of
insert second end 82 is
formed with a radiused or rounded concave surface which matches first end 62
of the
contact tip 32. This contact at the concave and convex surfaces provides
excellent
electrical and thermal conductivity between tip 32 and insert 30.
[0023] Now with reference to Figures 3-6, a first embodiment of
an end assembly of
the present invention is described. Elements of this first and the later
describe second
embodiment having equivalent function as in the prior art example described
above are
identified by like reference numbers. Referring in particular to Figure 3, end
assembly 92
is shown. In this instance, diffuser body 94 integrates the functions of the
previously
described prior art diffuser sleeve 28 and insert 30, such that the insert
component is not
used. Here, diffuser body 94 forms first end 96 and second end 98 with central
passageway 102 formed by internal bore 111 therebetween. Diffuser body 94
forms
internal threads 104 which receive a threaded end of gooseneck 22. Diffuser
body 94
further forms, at second end 98, a concave bore area having internal threads
106 which
mesh with external threads 108 of contact tip 110. Diffuser body 94 forms a
series of
radially extending passageways 112 which allow shielding gas to flow in a
radially outward
direction from internal passageway 102 into the annular space within nozzle
36. In a
manner similar to the previously described prior art example, diffuser body 94
forms
concave radiused seat surface 114 which closely conforms with matching convex
surface
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115 of first end 116 of contact tip 110. Concave and convex surfaces 114 and
115 are, in
geometric terms, formed by a curved line rotated about the central
longitudinal axis of tip
110. Contact tip 110 forms, as in the prior art, central longitudinal
electrode bore 118.
Differing from the prior art, in this embodiment contact tip 110 further forms
a series of
gas flow passageways 120 which are parallel to central bore 118 and spaced at
regular
angular intervals around the central bore. In one embodiment, three gas flow
passages
120 are formed, but other numbers could also be implemented. Shielding gas
under
pressure inside diffuser body 94 flows through radially outer passageways 102
and also
in a longitudinal direction into and through gas flow passageways 120.
[0024] When contact tip 110 is threaded into diffuser body 94,
the above-described
matching concave and convex surfaces 114 and 115 are brought into intimate
contact
which provides excellent electrical and thermal conductivity. The lowermost
surface of
contact tip 110 forms flattened first end 116. The radial positioning of gas
flow
passageways 120 is provided within flattened end 116 such that these
passageways do
not interfere with the previously described surface to surface contact
provided at surfaces
114 and115.
[0026] Figure 4 is an enlarged pictorial view of the inside of
diffuser body 94, viewed
in an upward direction from first end 96. As shown, this area features central
blind bore
section 122 formed with a radiused inside surface such as formed by a ball
mill type tool.
Between the surface formed by blind bore 122 and concave surface 115 is web
126. A
series of bores are formed through web 126 including central bore 123 provided
for
passage of electrode 48 and a series of radially offset bores 124 provided for
the flow of
shielding gas. Figure 5 shows diffuser body second end 98 viewed from above,
into the
diffuser second end 98. This view also shows annular seat surface 114 of
diffuser body
94 which mates with contact tip surface 115. As shown in Figure 5, bores 124
can be
provided radially displaced from the longitudinal axis of contact tip 110,
such that only a
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portion of the bore is exposed to chamber 128. It is necessary that bores 124
communicate with chamber 128 to provide gas flow passage.
[0026] Referring now in particular to Figures 3-5, web 126 is
displaced such that when
contact tip 110 is installed within diffuser body 94, there is a separation
between the base
first end 116 of the contact tip and web 126, forming chamber 128. As best
shown by the
arrows in Figure 3, shielding gas flows upwardly through internal passageway
102 and
some of the gas flows in a radially outward direction through diffuser body
passageways
112. Another portion of the gas continues to flow upward in an axial direction
through
bores 124 in web 126 and communicates with chamber 128. Chamber 128 enables
gas
flowing through holes 124 to communicate with contact tip passageways 112
regardless
of the rotational indexed final position of the contact tip when it is
threaded into diffuser
body 94. Chamber 128 provides a distribution of the shielding gas through each
of gas
flow passages 120. Another function of web 126 is to provide a surface
abutting the distal
end of wire guide 45 which is installed within diffuser body central bore 111
while further
allowing the flow of shielding gas to contact tip 110.
[0027] In this embodiment, contact tip central bore 118 is
dimensioned to be just
slightly larger than the outside diameter of electrode 48. This clearance
provides enough
space for smooth passage of electrode 48 while also providing the necessary
electrical
contact connection between contact tip 110 and the electrode. It is known that
electrode
48 can be provided having various cross-sectional shapes, the most typical
being a
circular or round shape. However, other shapes such ellipses and other non-
round
configurations can be provided. In these cases, the shape of the contact tip
bore and
associated electrode are matched.
[0028] Now with reference to Figures 7, 8 and 9, a second
embodiment of an end
assembly is shown, here designated by reference number 136. End assembly 136
utilizes
diffuser body 94 identical to the prior embodiment. Differences in end
assembly 136 relate
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to the configuration of contact tip 138. In this case, contact tip does not
feature the parallel
gas flow passages 120. Instead central nozzle bore 140 features an initial
larger diameter
section 142 and a distal section 144. Bore section 142 as a diameter
substantially larger
than the outside diameter of electrode 48 providing an annular space for the
flow of
shielding gas. However, distal bore section 144 closely conforms to the
outside surface
shape of the associated electrode 48 and provides electrical and thermal
contact with the
electrode. At the intersection of bore sections 142 and 144 a series of cross
bores 146
are provided. In a preferred embodiment cross bores 146 are perpendicular to
the
longitudinal axis of the nozzle and a pair are provided which are mutually
perpendicular.
Cross bores 146 terminate at a side outside surface of contact tip 138. In
this preferred
embodiment, four outside gas escape passages are formed by the pair of cross
bores
146.
[0029] Contact tip 138 of end assembly 136 features the same
interaction with diffuser
body 94, and provides the same convex and concave surfaces 114 and 115 for
contact
connection between contact tip 110 and diffuser body 94 which provides
excellent
thermal and electrical conductivity. These surfaces are formed outside the
diameter of
bore section 142.
[0030] Figure 7 shows and assembly 36 with wire guide 45
installed. As shown wire
guide 45 is seated against the end surface of blind bore 122. This
configuration would
also be used in the first embodiment of end assembly 92. As shown, bore 111
has a larger
diameter than the outside diameter of wire guide 45. Also, where wire guide 45
abuts the
blind end of bore 111, bores 124 are positioned outside the outer diameter of
the wire
guide providing for the flow path of shielding gas into chamber 128.
[0031] Figure 8 shows in drawn lines the flow of shielding gas
through and assembly
136. As shown, shielding gas is initially provided to the inside bore 111 of
diffuser body
94. A portion of the gas flow flows radially out of bores 112. Another portion
of the flow
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travels toward tip 138, flowing through offset bores 124 into chamber 128 and
into the
radial clearance provided between the enlarged bore section 142 and electrode
48. This
flow travels along contact tip 138 until it reaches the point of intersection
with cross bores
146 were the gas flows radially outward of the contact tip. A very small
proportion of the
gas is permitted to flow between the small radial clearance between electrode
48 and the
inside diameter of the small bore section 144. End assembly 136 is adapted to
be used
with nozzle 36 as shown in Figure 3. Accordingly the escaping shielding gas is
directed
to flow around the weld site at the distal end of contact tip 138.
[0032] Both embodiments of end assemblies 92 and 136 provided for
enhanced
cooling of the contact tips 110 and 138 since there is a significant flow of
shielding gas
through internal passages within the contact tips. This provides numerous
benefits. One
significant benefit is that, with the contact tips being kept at a cooler
temperature due to
heat transfer to the shielding gas, there is a reduced tendency of the distal
end of the
context tips 110 and 138 to accumulate welding splatter on the contact tips
which is a
major cause of maintenance requirements. Furthermore, excessive heating of the
contact
tips causes softening of the contact tip material which can lead to
enlargement of the
electrode bore at the distal end of the tip, which negatively impacts the
precision with
which the electrode wire 48 is directed to the workpiece and reduces effective
electrical
conduction with the electrode. Cooler contact tips during welding operations
has been
shown to significantly increase the useful life of the contact tips.
[0033] In the foregoing description, various features of the
present invention are
grouped together in one or more embodiments for the purpose of streamlining
the
disclosure. This method of disclosure is not to be interpreted as reflecting
an intention that
the claimed invention requires more features than are expressly recited in
each claim.
Rather, as the following claims reflect, inventive aspects lie in less than
all features of a
single foregoing disclosed embodiment. Thus, the following claims are hereby
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incorporated by reference herein in their entirety, with each claim standing
on its own as
a separate embodiment of the present invention.
[0034] It is intended that the foregoing description be only
illustrative of the present
invention and that the present invention be limited only by the hereinafter
appended
claims.
[0035] While the above description constitutes the preferred
embodiment of the
present invention, it will be appreciated that the invention is susceptible to
modification,
variation and change without departing from the proper scope and fair meaning
of the
accompanying claims.
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