Electric arc welding gun

An apparatus for welding a workpiece comprises a body tube having a tapered portion defining a first angle, and an end fitting releasably connectable with the body tube and having a tapered portion defining a second angle. The tapered portion of the body tube is releasably connectable with the tapered portion of the end fitting. The first angle differs from the second angle by a distance sufficient for facilitating manual separation of the tapered portion of the body tube from the tapered portion of the end fitting. A liner has a first portion disposed within the end fitting and a second portion disposed within the body tube. A connection member operatively releasably connects the first portion of the liner with the second portion of the liner. A member is disposed on the body tube or the end fitting for releasably connecting the body tube to the end fitting. A positive stop member is formed the body tube or the end fitting for positively retaining the member on the body tube or the end fitting.

BACKGROUND OF THE INVENTION 
The present invention relates generally to a novel construction for an 
improved welding apparatus, and more specifically to a novel construction 
for an improved electric arc welding gun/torch. 
Welding processes are widely used in modem day manufacturing. One such 
welding process is commonly referred to as arc welding, which utilizes an 
electrical current, and an electrode. The American Welding Society ("AWS") 
defines arc welding with seven subclasses, viz. shielded metal arc 
welding, submerged arc welding, gas metal arc welding, flux cored arc 
welding, gas tungsten arc welding, plasma arc welding, and electroslag 
welding. Electrical current heats the tip of an electrode such that the 
electrode and the adjacent portions of the workpiece become hot enough to 
fuse. In order to prevent molten metal from reacting with components of 
the surrounding ambient atmosphere, a fluid flow of a shielding gas, such 
as helium, argon and the like, or a solid slag surrounds the molten metal 
and the adjacent portions of the workpiece. 
In some instances, these things needed for arc welding are provided in the 
form of a welding apparatus or gun which facilitates manipulation of the 
electrode and the shield by a workman during welding. One example of an 
arc welding gun of the prior art generally comprises a handle member 
connected to an end of a composite cable which delivers arc power and 
shielding gas from suitable sources. A cone nut is located at the end of 
the composite cable, and the cone nut has threads connectable with 
complementary threads on an end fitting. The end fitting has another set 
of threads which are engagable with complementary threads on a lock nut 
for operatively connecting a body tube to the end fitting. Because the end 
fitting and the body tube are electrically conductive, an insulating 
member may be positioned over exposed portions of the end fitting and the 
lock nut. A liner, in which a consumable electrode can be inserted, 
extends through the composite cable and the body tube, and terminates 
adjacent a distal end of the body tube. A contact tip for weldingly 
contacting the electrode is disposed at the distal end of the body tube. 
Currents used in arc welding can be on the order of hundreds of Amps. These 
currents generate sufficient heat, especially at and adjacent the contact 
tip, which, in combination with other effects of arc welding, can cause 
deterioration of portions of the welding gun. The body tube and the liner 
are often susceptible to this deterioration. In addition, body tubes may 
have certain, predetermined configurations which make them particularly 
adept at forming a certain weld, may have particular utility with a given 
workpiece, etc. The liner may be abraded within the body tube as the 
electrode is continuously used. Therefore, it may become desirable to 
replace the body tube and/or the liner in order to insure efficient 
welding of the workpiece. However, the method of replacing a body tube 
and/or a liner may be quite difficult or tedious and may be relatively 
expensive in time and in labor. 
A typical method of replacing a body tube A may be more easily understood 
with reference to FIG. 2. To replace a body tube A, the handle member must 
be removed. The insulating member is slid off of the lock nut B and the 
end fitting C to reveal the driving flats of both elements. The cone nut D 
at the end of the composite cable E is inserted into a vise F, and the 
vise F is activated to firmly hold the cone nut D against rotation. Now, a 
first wrench is applied to the lock nut B to rotate the lock nut B with 
respect to the end fitting C to disengage the threaded connection 
therebetween. A second wrench is applied to the end fitting C to fix the 
end fitting C against rotation with respect to the cone nut D or the lock 
nut B. Force is applied to the first wrench to rotate the lock nut B while 
another force is applied to the second wrench to hold the end fitting C 
fixed. This force application continues or is increased until the threaded 
connection between the lock nut B and the end firing C is loosened. Once 
the connection is loosened, the body tube A is rotated with the lock nut B 
and removed completely from the end fitting E. 
Because the threaded connection between the lock nut B and the end fitting 
C is torqued, often to about 15 foot-pounds, the forces required to break 
the threaded connection may be rather significant. In addition, 
appropriate portions of the body tube A and/or the end fitting C may be 
tapered at a slight incline. This taper may make the time required to 
disassemble the body tube A and the end fitting C rather long, which 
increases the down time of the welding gun, and which possibly 
correspondingly decreases the amount of revenues that can be generated by 
use of the gun. Alternatively, two workmen, one working each of the 
wrenches, may cooperate to loosen the connection, but this method is 
relatively labor intensive, thereby also possibly decreasing associated 
revenues. 
The liner extends through the axial length of the composite cable E and 
into the body tube A. The liner may be ten to fifteen feet long or longer 
depending upon the length of the composite cable E desired for a specific 
welding application. While the old liner may be relatively easily removed 
by pulling it through the open, distal end of the composite cable 
connection, the new liner will have to be carefully inserted through the 
entire length of the composite cable E. This installation process may be 
tedious, requires removal of the welding gun from production, possibly 
further reducing revenues. In addition, it is to be noted that the 
operative welding temperatures, about 400 degrees Fahrenheit, tend to be 
concentrated at the contact tip of the welding gun. Thus, significant 
deterioration of the liner may only occur immediately adjacent the contact 
tip. This means that, in some instances, deterioration of a few inches of 
the liner may require replacement of the entire liner, which may be almost 
an order of magnitude longer than the deteriorated portion of the liner. 
Because the entire liner must be replaced due to deterioration of such a 
small portion thereof, liner replacement of the present art can be 
wasteful and also costly. These things can increase the costs of 
maintaining and/or using a welding gun because of increased labor and 
parts costs. 
Because of these characteristics, among others, of some prior art welding 
apparatuses, such as arc welding guns and the like, it is desirable to 
provide an improved welding apparatus which is not subject to some, if not 
all of the above-discussed characteristics of the prior art welding guns. 
The present invention is intended to provide such an improvement. 
SUMMARY OF THE INVENTION 
The present invention provides an improved welding apparatus, such as an 
arc welding gun and the like. The welding gun facilitates removal of a 
body tube therefrom without the use of tools, thereby possibly reducing 
the time and labor needed to replace a body tube. In addition, with the 
welding gun of the invention, it is not necessary to replace the entire 
axial length of a liner to remove a relatively small deteriorated distal 
portion of the liner. The welding gun of the invention may be less costly 
to repair and maintain than some prior art welding guns, and it is 
possible that utilization of the novel welding gun may result in revenue 
savings to a user. 
A general object of an embodiment of the present invention is to provide a 
novel construction for a welding apparatus, and especially for an arc 
welding apparatus. 
A more specific object of an embodiment of the invention is to provide a 
novel construction for a welding gun, and especially for an arc welding 
gun. 
Another object of an embodiment of the present invention is to provide a 
novel welding gun having a body tube which is replaceable quicker and 
easier than some prior art body tubes. 
An additional object of an embodiment of the invention is to provide a 
novel welding gun having a body tube which can be removed without the aid 
of other tools. 
A further object of an embodiment of the present invention is to provide a 
novel welding gun having a construction which makes liner replacement 
easier than some prior art welding guns. 
A novel welding apparatus, constructed according to the teachings of the 
present invention, comprises a body tube having a tapered portion defining 
a first angle, and an end fitting releasably connectable with the body 
tube and having a tapered portion defining a second angle. The tapered 
portion of the body tube is releasably connectable with the tapered 
portion of the end fitting. The first angle differs from the second angle 
by a distance sufficient for facilitating manual separation of the tapered 
portion of the body tube from the tapered portion of the end fitting. A 
liner has a first portion disposed within the end fitting and a second 
portion disposed within the body tube. A connection member operatively 
releasably connects the first portion of the liner with the second portion 
of the liner. A member is disposed on one of the body tube or the end 
fitting for releasably connecting the body tube to the end fitting. A 
positive stop member is formed on the one of the body tube or the end 
fitting for positively retaining the member on the body tube or the end 
fitting.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
While the invention may be susceptible to embodiment in different forms, 
there are shown in the drawings, and herein will be described in detail, 
specific embodiments with the understanding that the present disclosure is 
to be considered an exemplification of the principles of the invention, 
and is not intended to limit the invention to that as illustrated and 
described herein. 
Referring initially to FIG. 1, a novel arc welding gun 10, constructed 
according to the teachings of the present invention, is illustrated. It is 
to be noted that, while the embodiments of the invention will be discussed 
herein with respect to their employment with arc welding, for the sake of 
clarity, the embodiments of the invention may be used with any suitable 
type of manufacturing process without departing from the scope of the 
invention. In addition, while the embodiments of the invention will be 
discussed separately, again for the sake of clarity, it is to be fully 
understood that the embodiments can be combined in any suitable manner 
without departing from the scope of the invention. Also, some elements of 
the novel welding gun 10 are well known to those having ordinary skill in 
the art, and, thus, those elements of the welding gun 10 will be discussed 
only with sufficient detail necessary to provide the reader with an 
appreciation of the embodiments of the invention. Furthermore, the 
embodiments of the present invention can be utilized with certain existing 
welding apparatuses and guns, such as the EZ FEED and EZ FEED II welding 
guns available from Bernard Welding Equipment Company of Beecher, Ill. 
The welding gun 10 generally comprises a handle portion 12, haft of which 
is shown in FIG. 1, a composite cable 14, an end fitting 16, and a body 
tube 18. The handle portion 12 can be made of an electrically insulating 
material, such as a plastic, and may have a configuration adapted for 
facilitating manipulation of the welding gun 10 by a workman. The 
composite cable 14 may be of well known construction and is connected at 
one end to a suitable source of electrical power and shielding gas, such 
as helium, argon, carbon dioxide, and the like, not shown. An opposite end 
20 of the composite cable 14 is operatively connected to a proximal end of 
the end fitting 16 by suitable means. The composite cable 14 may have any 
axial length sufficient to position the welding gun 10 for welding. A 
cable liner 22 extends substantially axially through the hollow interior 
of the composite cable 14 and the end fitting 16 in well known fashion. 
However, a proximal portion of the cable liner 22 terminates distally 
within the end fitting 16. This is an important difference from some of 
the welding guns of the prior art, and the significance of this 
construction will become more clear later. This cable liner 22 
construction allows for replacement of a deteriorated portion of the liner 
22 without requiring replacement of the entire liner 22, as discussed 
earlier with respect to FIG. 2. 
The body robe 18 comprises an inner element 24, made of a conductive metal 
such as copper, and an outer element 26, made of a metal such as brass. An 
insulating element 27, made of an appropriate material, such as a high 
temperature TEFLON, nylon, or the like, is disposed between the inner 
element 24 and the outer element 26, which are releasably connectable to 
the end fitting 16. The insulating element 27 prevents electrical current 
from flowing from the inner element 24 to the outer element 26. The body 
tube 18 is straight or bent to define an angle for facilitating the 
welding process, The angle usually measures 22.5, 30, 45, 60 or 180 
degrees. The body tube 18 has a distal welding end 28, opposite to the end 
of the body tube 18 connected to the end fitting 16, which terminates at a 
contact tip 30 for weldingly contacting an electrode, not shown. A 
majority of deterioration of the liner 22 occurs proximate to the contact 
tip 30. A member or locking nut 32 is disposed around the body tube 18 
adjacent the end thereof connectable to the end fitting 16 for firmly 
attaching the end fitting 16 to the body tube 18. The body tube 18 also 
includes a through bore 34 extending along the axial length of the body 
tube 18. The through bore 34 is dimensioned for accepting a jumper liner 
36, which forms an operative extension of the cable liner 22. The 
significance of the jumper liner 36 will be discussed further below. 
As shown in FIGS. 1 and 3, the end fitting 16 has a through bore 38 for 
accepting the cable liner 22 and a portion of the body tube 18 and the 
locking nut 32. Specifically, the through bore 38 comprises a 
substantially cylindrical portion 40, a substantially tapered portion 42, 
and an internally threaded portion 44 including female threads 46. The 
cylindrical portion 40 has an inner diameter larger than the outer 
diameter of the cable liner 22 so that the cable liner 22 can be inserted 
through the cylindrical portion 40. The tapered portion 42 which forms 
part of a novel structure of the welding gun 10, is located between the 
cylindrical portion 40 and the threaded portion 44, and the inner surface 
thereof defines an angle .alpha. with respect to a longitudinal axis, 
represented by dotted line 48 in FIG. 3. In the illustrated embodiment, 
the angle .alpha. measures about 2 degrees. The threads 46 on the threaded 
portion 44 are matable with complementary male threads 50 on a threaded 
portion 52 of the locking nut 32 to releasably join the end fitting 16 to 
the body tube 18. The threads 46 and 50 define a thread profile common to 
the similar structures on other welding apparatuses available from Bernard 
Welding Equipment Company of Beecher, Ill. This facilitates 
interchangability of the embodiments of the present invention with 
existing welding equipment. 
The body tube 18 also includes novel structures unique to the welding gun 
10. A proximal end 54 of the body tube 18, and specifically the inner 
element 24, includes a tapered portion 56 whose outer surface defines an 
angle .beta. with respect to the longitudinal axis 48, shown in FIG. 3, 
which measures about 2.5 degrees. It is to be noted that there is an 
angular differential, measuring about 0.5 degrees, between the angle 
.alpha. and the angle .beta.. This precise measure of this differential 
and the angles .alpha. and .beta. is subject to usual manufacturing 
tolerances. This differential facilitates removal of the body tube 18 from 
the end fitting 16, thereby providing for relatively quick change of the 
body tube 18 and the jumper liner 36 without the need of tools, even when 
the threaded connection between the end firing 16 and the body tube 18 is 
torqued to about 30 inch pounds. This advantage of the present invention 
will be discussed in greater detail later. 
The body tube 18 has a substantially cylindrical portion 58 located 
distally of the tapered portion 56. The locking nut 32 is located around 
the cylindrical portion 58. In order to positively locate and retain the 
locking nut 32 about the cylindrical portion 58, a snap ring 60 is 
attached to the outer diameter surface of the cylindrical portion 58 to 
limit movement of the locking nut 32 in one direction. As is illustrated 
more clearly in FIGS. 3 and 6, a proximal end of the locking nut 32 has an 
annular recess 62 or increased inner diameter portion dimensioned for 
accepting and covering a portion of the snap ring 60. The annular recess 
62 insures that the snap ring 60 will remain in place on the cylindrical 
portion 58 when substantial loads are applied thereto, and also cooperates 
with the snap ring 60 to form positive stop means for limiting movement of 
the locking nut 32 on the cylindrical portion 58 toward the end fitting 
16. 
In order to positively retain the locking nut 32 on the cylindrical portion 
58, a distally located positive stop means is also required. This distally 
located positive stop means is formed by swaging the material comprising 
the inner element 24 of the body tube 18 to create a protuberance or 
raised step 64 on the outer surface of the inner element 24. The step 64 
may be annular and projects substantially radially away from the outer 
surface of the inner element 24 a distance sufficient for positively 
limiting distal movement of the locking nut 32 on the cylindrical portion 
58. In the illustrated embodiment, the step 64 extends away from the outer 
surface of the cylindrical portion 58 approximately 0.015 inches. It is to 
be noted, as is evident from FIGS. 1, 3 and 6, that the inner diameter 
surface of the cylindrical portion 58 of the body tube 18 remains 
substantially constant, and that the inner diameter of the cylindrical 
portion 58 is not increased or decreased by the formation of the step 64. 
Furthermore, by forming the step 64 by a swaging procedure, the overall 
strength of the body tube 18 is increased. 
The locking nut 32 also includes an annular recess 66 or increased inner 
diameter portion located distally of the annular recess 62. The annular 
recess 66 is dimensioned to accept the step 64, and cooperates with the 
step 64 to limit distal movement of the locking nut 32 along the body tube 
18. Thus, the relative axial locations of the annular recesses 62 and 66 
on the locking nut 32 and of the snap ting 60 and the step 64 on the 
cylindrical portion 58 are predetermined to positively limit the range of 
axial movement of the locking nut 32 along the outer diameter surface of 
the cylindrical portion 58. However, it is to be remembered that those 
relative axial locations are chosen to provide sufficient axial movement 
of the locking nut 32 to facilitate joinder of the body tube 18 to the end 
fitting 16, and that the locking nut 32 is free to rotate about the 
cylindrical portion 58. Also, while the illustrated embodiment shows one 
step 64 and one snap ring 60 forming the positive stop means, it is 
envisioned that the snap ring 60 can be replaced by another step 64 
without departing from the invention. 
As stated above, the body tube 18 can be releasably joined to the end 
fitting 16 without the aid of tools. Thus, the threads 50 on the locking 
nut 32 are engagable with the threads 46 on the end fitting 16 by hand. To 
facilitate this manual joining of the end fitting 16 with the body robe 
18, the locking nut 32 comprises an inner element 68 and a hand nut or 
outer element 70. The inner element 68 is formed from a metal, such as 
brass and the like, and is constructed substantially similarly to the 
locking nuts of the prior art. The outer element 70 is formed of an 
electrically insulating plastic material which can withstand the operating 
temperatures of the welding gun 10, which are about 390 degrees 
Fahrenheit, and can hold at least 8 foot-pounds of torque. The currently 
preferred material for the outer element 70 is GLASTIC 1412AD (black) 
which is available from Glastic, Inc. 
The outer element 70 can be overmolded onto the inner element 68, or, 
alternatively, may be molded as a separate piece, slid over the inner 
element 68 and secured thereto by means of a mechanical or chemical 
fastening system. In order to insure firm attachment of the inner element 
68 to the outer element 70, the inner element 68 is provided with means 
for keying the inner element 68 to the outer element 70. In the 
illustrated embodiment, this keying means takes the form of a pair of 
annular recesses 72A and 72B or reduced outer diameter portions located 
along the shank of the inner element 68. If the outer element 70 is 
overmolded onto the inner element 68, the plastic material of the outer 
element 70 flows into the annular recesses 72A and 72B, thereby insuring a 
firm bond between the inner element 68 and the outer element 70. The 
locking nut 32 includes a plurality of driving flats 101 which can assist 
in efficient torque transmittal from the outer element 70 to the inner 
element 68 to threadibly engage the male threads 50 on the locking nut 32 
with the female threads 46 on the end fitting 16. 
The locking nut 32, and specifically the outer element 70, is provided with 
a configuration for facilitating manual attachment of the end fitting 16 
to the body tube 18. This configuration is more clearly illustrated in 
FIGS. 4 and 5. The illustrated embodiment of the configuration of the 
locking nut 32 comprises a series of alternating lobes 74 and flutes 76 
disposed along the circumference of the outer element 70. Preferably, 
there are six lobes 74 and six flutes 76 disposed equidistantly along the 
circumference of the outer element 70, i.e. located every sixty degrees 
along the circumference. In addition, each lobe 74 includes knurls 78 
which can provide for a better grip of the outer element 70. This 
configuration and the outer element 70 in general facilitate torque 
transfer from a workman's hand to the inner element 68, which includes the 
male threads 50. Thus, the locking nut 32 and the end fitting 16 can be 
joined by hand, and the desired torquing of the threaded joint between the 
end fitting 16 and the locking nut 32 can be accomplished manually without 
the need of tools. This can reduce the amount of time required to change 
liners 22 and body tubes 18. In addition, because the end fitting 16 and 
the locking nut 32 are tightened and torqued by hand, the possibility of 
over-torquing of the threaded joint therebetween is reduced. Furthermore, 
the construction of the body tube 18 and the end fitting 16 allows the 
body tube 18 to be rotated with respect to the end fitting 16 when the 
threaded joint between the end fitting 16 and the body tube 18 is tightly 
tightened or torqued. The body tube 18 can be rotated through a full three 
hundred and sixty degree arc about its axis, thereby allowing the 
positioning of the contact tip 30 to a desirable working, operational 
position. These things can provide greater flexibility in welding and 
represent significant improvements over the welding apparatuses of the 
prior art. 
As noted above, the outer dement 70 is made from an electrically insulating 
material. This is necessary because the inner dement 68 is placed within 
the current path through the welding gun 10. The currents can be quite 
large, on the order of hundreds of Amps. Specifically, it is expected that 
the welding gun 10 may be made commercially available in at least 200, 350 
and 500 Amp models. Because of these large currents, there may be a 
possibility that electrical energy may arc across a gap, such as the 
annular gap 80 between a potential ground circuit, not shown, and the 
inner element 68 of the locking nut 32. In order to reduce the probability 
of arcing across the gap 80, an insulating member 82 is located within the 
gap 80. In an exemplary embodiment, the insulating member 82 comprises a 
rubber O-ring surrounding the locking nut 32 between the threads 46 and 
the annulus of the inner element 68. 
In addition to providing for relatively quick replacement of the body tube 
18, an embodiment of the invention also provides for relatively quick and 
easy replacement of the cable liner 22. As stated earlier, a portion of 
the cable liner 22 may deteriorate during welding operation of the welding 
gun 10. This deterioration tends to be concentrated at a distal portion of 
the cable liner 22 adjacent the contact tip 30 of the body tube 18, while 
the proximally located portions of the cable liner 22 may remain 
substantially intact. Thus, it may be more economical to replace only a 
small, deteriorated portion of the cable liner 22 than to replace the 
entire axial length thereof. In addition, by replacing only a small 
portion of the cable liner 22, the down time of the welding gun 10 can be 
reduced because the new cable liner 22 would not have to be inserted 
through the entire length of the composite cable 14. The novel welding gun 
10 of the present invention has unique structures which allow this to be 
done. 
As shown more clearly in FIGS. 4 and 6, the welding gun 10 includes a 
connection member 84 which releasably couples the cable liner 22 in the 
composite cable 14 with the jumper liner 36 in the body tube 18 such that 
the jumper liner 36 forms an operative extension of the cable liner 22. 
Accordingly, while the cable liner 22 within the composite cable 14 may be 
of the usual length, the length of the jumper liner 36 may be only about 
the length of any body tube 18. Because the jumper liner 36 is so much 
shorter than the cable liner 22, the jumper liner 36 may be less expensive 
compared to the cable liner 22, and the time required to change the jumper 
liner 36 as compared to the cable liner 22 may be correspondingly reduced. 
This can reduce the down time of the welding gun 10, and may provide the 
user with correspondingly increased revenues. 
The construction of the connection member 84 is shown in FIGS. 4 and 6. As 
illustrated, the connection member 84 has a substantially cylindrical 
configuration, but it is to be recognized that other configurations are 
also possible as long as the connection member 84 is insertable, in the 
illustrated embodiment, into the through bore 34 in the body tube 18. The 
connection member 84 is preferably made from a metal, such as brass, but 
other materials can also be used. 
The connection member 84 comprises a first portion 86 for accepting an end 
of the cable liner 22 and a second portion 88 which accepts an end of the 
jumper liner 36. The first portion 86 has an outer diameter larger than 
the outer diameter of the second portion 88 and substantially equal to the 
inner diameter of the tapered portion 56 and the cylindrical portion 58 of 
the body tube 18. This construction allows the connection member 84 to be 
inserted into and fit relatively snugly within the through bore 34 in the 
body tube 18. The first portion 86 has an inner diameter larger than the 
outer diameter of the cable liner 22 and an inner diameter of the second 
portion 88, which is substantially equal to the outer diameter of the 
jumper liner 36. Because the inner diameter of the first portion 86 is 
larger than the outer diameter of the cable liner 22, the cable liner 22 
can be inserted into the first portion 86. Moreover, because of the 
diametric differential between the cable liner 22 and the first portion 
86, the inserted end of the cable liner 22 can float within the first 
portion 86. Thus, the cable liner 22 can float or move within the first 
portion 86 to accommodate stretching of the composite cable 14, which 
controls movement of the cable liner 22. 
In an alternative construction of the connection member 84, the distal end 
of the cable liner 22 may not be inserted into the connection member 84, 
but the distal end of the cable liner 22 may butt up against a proximal 
end of the first portion 86. With this alternative construction, the first 
portion 86 does not need the large inner diameter discussed above. 
The first portion 86 also has a external configuration for facilitating the 
functionality of the welding gun 10. Specifically, as is shown more 
clearly in FIG. 4, the first portion 86 has a number of alternating flutes 
90 and lobes 92 equidistantly spaced along the circumference of the first 
portion 86. In the illustrated embodiment, there are four flutes 90 and 
four lobes 92, although other numbers are also possible. The flutes 90 
define outer diameters smaller than the outer diameters deemed by the 
lobes 92. The flutes 90 form channels which extend along the axial length 
of the first portion 86 for allowing gas to pass from the end fitting 16 
into the body tube 18. 
The lobes 92 also extend along the entire axial length of the first portion 
86, define the boundaries of the flutes 90 and form bearing surfaces 
engagable with the inner diameter surfaces of the tapered portion 56 and 
the cylindrical portion 58 of the body robe 18, as shown in FIG. 6. Thus, 
the lobes 92 substantially center the connection member 84 within the 
through bore 34 in the body tube 18, which provides for easier insertion 
of the cable liner 22 into the first portion 86. A proximal end of the 
first portion 86, opposite to the end thereof connected to the second 
portion 88, is configured to form flanges 94 extending radially outwardly 
from ends of the lobes 92. The flanges 94 act as positive stops for 
positively locating the connection member 84 within the body tube 18. In 
an exemplary embodiment, there is at least one flange 94 associated with 
each lobe 92. The flanges 94 define an outer diameter greater than the 
inner diameter of the tapered portion 56 of the body tube 18 and contact 
the end 54 of the tapered portion 56 of the body tube 18 to limit movement 
of the connection member 84 into the body tube 18. 
As stated above, the second portion 88 has an inner diameter substantially 
equal to the outer diameter of the jumper liner 36 so that the jumper 
liner 36 is insertable into the second portion 88. In addition, the first 
portion 86 has a reduced inner diameter segment 98 adjacent the second 
portion which defines an inner diameter substantially equal to the outer 
diameter of the jumper liner 36. An end of the jumper liner 36 is inserted 
through the second portion 88 up to the proximal end of the segment 98, as 
shown in FIG. 6. The jumper liner 36 is fastened within the second portion 
88 by means of a crimp 100 formed on the second portion 88. In this 
manner, when the cable liner 22 is inserted into the first portion 86, the 
jumper liner 36 forms an operative extension of the cable liner 22 so that 
the cable liner 22 effectively extends through the composite cable 14 to a 
position adjacent the contact tip 30 of the body tube 18. Once operatively 
extended, a conductor or electrode can be threaded through the cable liner 
22 in common fashion. 
The embodiments of the present invention provide a number of distinct 
advantages over the welding apparatuses of the prior art. The angular 
differential between the tapered portion 42 of the end fitting 16 and the 
tapered portion 56 of the body tube 18 facilitates loosening of the end 
fitting 16 and the body tube 18, which maintains current flow between the 
end fitting 16 and the body tube 18. The precise measure of the angles 
defined by the tapered portions 42 and 56 is not as important as the 
differential between those angles. Accordingly, it is envisioned that the 
tapered portions 42 and 56 could define a number of different angles 
without departing from the scope of the invention, as long as the 
differential or distance between the angles is sufficient for facilitating 
manual separation of the tapered portion 42 of the end fitting 16 and the 
tapered portion 56 of the body tube 18. Preferably, this differential or 
distance is about 0.5 degrees. The outer element 70 of the locking nut 32 
allows the locking nut 32 to be threadibly attached by hand. This, along 
with the thread profiles and the limits of unaided human strength, may 
prevent over-torquing of the threaded connection between the end fitting 
16 and the body tube 18. The locking nut 32 also allows the body tube 18 
to rotate about its axis along a three hundred and sixty degree arc, and 
thereby allows for easy changes of the orientation of the body tube 18. 
The construction of the jumper liner 36 and the connection member 84 allows 
for easier and more economical replacement of a deteriorated portion of 
the cable liner 22, as compared to some welding apparatuses of the prior 
art. Stretching of the composite cable 14, which effectively moves the 
cable liner 22 during operation of the welding gun 10 is compensated for 
by the clearance between the outer diameter of the cable liner 22 and the 
inner diameter of the first portion 86 of the connection member 84, i.e. 
the cable liner 22 floats within the first portion 86 of the connection 
member 84 as the cable liner 22 stretches. The flutes 90 allow for 
shielding gas to flow over the connection member 84 during welding so that 
the presence of the connection member 84 does not affect the efficiency of 
the welding gun 10. The protuberance or step 64 positively retains the 
locking nut 32 on the body tube 18 and positively limits axial movement of 
the locking nut 32 with respect to the body tube 18. In addition, by 
forming the step 64 by swaging the material of the body tube 18, the body 
tube 18 has increased strength as compared to a body tube 18 comprised of 
unswayed material. Each of these embodiments can be combined in any 
suitable fashion, and the embodiments may also be utilized with existing 
welding equipment. 
While embodiments of the present invention are shown and described, it is 
envisioned that those skilled in the art may devise various modifications 
of the present invention without departing from the spirit and scope of 
the appended claims.