Water cooled gas metal arc welding gun

A water cooled gas metal arc welding (MIG) gun which is provided with a water cooling system for the gun barrel that introduces the coolant water at the bottom of the barrel to create a coolant water flow through the gun that does not allow the coolant water to stagnate and heat up. The gun includes a water cooled shielding gas cup on the lower end that ensures coolant water flow therethrough, and provides metal thickness at the end of the cup which prevents physical abuse of the cup from affecting the guns' performance. The gun has a shielding gas delivery system which ensures good shielding gas flow and allows for replaceable shielding gas diffusers.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The field of art to which this invention pertains may be generally located 
in the class of devices relating to electric arc welding. Class 219, 
Electric Welding, United States Patent Office Classification, appears to 
be the applicable general area of art to which the subject matter similar 
to this invention has been classified in the past. 
2. Description of the Prior Art 
This invention relates generally to the gas metal arc welding (GMAW) art, 
also referred to as the metal inert gas (MIG) art, and more particularly, 
to a water cooled MIG welding gun constructed and arranged to handle the 
extreme temperatures encountered in gas metal arc welding applications. 
Heretofore, it has been an extremely difficult problem to use the 
progressive manual cast welding technique known as "Flood Welding" with 
flux-cored welding wire. This problem is due to the fact that the 
equipment to use it has not been capable of withstanding the extreme 
temperatures of the environment in which this type of welding takes place. 
The mass of the part being welding is generally heated to 900 degrees 
Fahrenheit, and the arc temperature of the flux-cored wire used with a MIG 
gun is between 7,000 degrees Fahrenheit and 10,000 degrees Fahrenheit. The 
arc and ambient temperatures are within two inches of the end of the MIG 
gun, and the MIG gun can run continuously for periods of hours. The 
welding gun equipment on the market today, while capable of doing some of 
the necessary work has not been able to consistently work without burning 
up. 
SUMMARY OF THE INVENTION 
The invention provides a water cooled gas metal arc MIG welding gun which 
is capable of withstanding the extreme temperatures of the environment in 
which "flood welding" with flux-cored welding wire takes place. The 
welding gun of the present invention includes an inner barrel having an 
axial passage for the conveyance therethrough of flux-cored welding wire 
which then passes through a shielding gas diffuser and an electrically 
conductive contact tip. An outer barrel is telescopically mounted around 
the inner barrel in a radially spaced apart position, to form a 
cylindrical longitudinal pressurized coolant water passage around the 
inner barrel. A tubular water cooled cup assembly is mounted on the lower 
end of the gun, and it surrounds a shielding gas diffuser and a 
electrically conductive contact tip, and provides a discharge passage to 
permit shielding gas emitted from the shielding gas diffuser to flow 
downwardly and outwardly over the welding area. The tubular water cooled 
cup assembly includes a cylindrical pressurized longitudinal coolant water 
chamber which is supplied with a coolant water inlet tube and an outlet 
tube for discharging coolant water after it has moved around and through 
the cylindrical coolant chamber in the cup assembly. 
The pressurized coolant water for the inner barrel is admitted at the 
bottom of the cylindrical longitudinal coolant passage and it flows upward 
to prevent the water from stagnating and heating up. The water cooled cup 
assembly is constructed to ensure optimum coolant water flow, and metal 
thickness at the lower end of the cup, so that physical abuse of the cup 
does not affect its performance. The shielding gas system ensures good 
shielding gas flow and permits quick and easy replacement of the gas 
diffusers.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, and in particular to FIGS. 1 and 8, the 
numeral 10 generally designates a water cooled gas metal arc welding (MIG) 
gun made in accordance with the principles of the present invention. It 
will be understood that the welding gun 10 is used in a vertical position, 
as illustrated in FIG. 1, and accordingly, the various parts of the 
welding gun 10 will be referred to as having an upper end and a lower end. 
As shown in FIG. 3, the welding gun 10 employs a conductive gun barrel 
structure that includes an inner elongated barrel 11 which comprises a 
copper tube. As shown in FIG. 3, the upper end 12 of the inner barrel 11 
is seated within the tubular lower end or hub 13 of a conductive gun 
header, generally indicated by the numeral 14. The gun header 14 is made 
from copper and it is fixedly secured to the upper end 12 of the inner 
barrel 11 by any suitable means, as by being silver soldered thereto. 
The welding gun 10 further includes a water cooled conductive outer barrel 
15 which comprises an elongated copper tube. The upper end of the outer 
barrel 15 is seated around the hub 13 on the gun header 14 and is fixedly 
secured thereto by any suitable means, as by being silver soldered 
thereto. The lower end of the outer barrel 16 is seated around the 
periphery of a cylindrical gas diffuser sleeve, which is generally 
indicated by the numeral 16. The lower end of the inner barrel 11 is 
seated against the upper end of the gas diffuser sleeve 16. The inner and 
outer barrels 11 and 15 are fixedly secured to the gas diffuser sleeve 16 
by any suitable means, as by being silver soldered thereto. As illustrated 
in FIG. 8, the welding gun 10 includes a tubular or cylindrical barrel 
insulator member, generally indicated by the numeral 20, which is slidably 
mounted over the outer barrel 15 and which has its upper end seated 
against the gun header 14. The barrel insulator 20 is fixedly secured in 
position on the outer barrel 15 by any suitable means as by a press fit. 
The barrel insulator 20 includes an upper portion 21, and an integral 
lower portion 22 which has a smaller diameter. The barrel insulator 20 is 
made from any suitable insulating material, as for example a black 
"TEFLON" tubing available on the market under No. PL-583. 
As shown in FIGS. 5 and 8, the welding gun 10 includes a water cooled 
copper cup assembly, generally indicated by the numeral 23, which is 
operatively mounted on the lower end of the gun 10. As shown in FIG. 6, 
the water cooled copper cup assembly 23 includes an upper cylindrical 
copper sleeve or tube member 29 which has its lower end fixedly secured 
around the upper end of a water cooled cup chamber sleeve 26. The water 
cooled copper cup assembly 23 further includes a lower sleeve or tube 
member 25 which is mounted around the lower end of the water cooled cup 
chamber sleeve 26. The lower end of the upper sleeve 24 abuts the upper 
side of a peripheral shoulder 28 on the water cooled cup chamber sleeve 
26. The upper end of the water cooled cup lower sleeve 25 abuts the lower 
side of the peripheral shoulder 28 on the water cooled cup chamber sleeve 
26. The upper sleeve 23 and the lower sleeve 25 are fixedly secured to the 
water cooled cup chamber sleeve 26 by any suitable means, as by being 
silver soldered thereto. The water cooled copper cup assembly 23 is 
slidably mounted over the lower end of the reduced diameter integral 
portion 22 of the barrel insulator 20 and it is secured thereto by any 
suitable means as by a press fit. The upper end of the upper sleeve of the 
water cooled copper cup 23 abuts a shoulder 27 (FIG. 5) formed at the 
junction point between the larger diameter portion of the barrel insulator 
upper portion 21 and the barrel insulator lower and smaller diameter 
portion 22. As shown in FIG. 6, the inner bore 29 in the water cooled 
copper cup upper sleeve 23 is made to a dimension to slidably receive the 
lower smaller diameter barrel insulator portion 22. 
As shown in FIG. 8, a shielding gas diffuser or nozzle 30 is mounted in the 
lower end of the gas diffuser sleeve 16. The shielding gas diffuser 30 has 
a reduced diameter, threaded upper end 31 which is threadably mounted in 
the threaded lower end of a stepped bore 33 that is formed through the gas 
diffuser sleeve 16. The shielding gas diffuser 30 has formed therethrough 
an axial bore 34 which is provided with an internal threaded lower end 35, 
and in which is threadably mounted the upper threaded end 36 (FIG. 2) of 
an electrically conductive contact tip 37. As shown in FIG. 8, the 
shielding gas diffuser 30 and the electrically conductive contact tip 37 
are disposed within an axial bore 38 formed through the water cooled 
copper cup chamber 26 and in a position radially spaced therefrom, to 
provide a passage for shielding gas emitted by the shielding gas diffuser 
30. 
As shown in FIGS. 2 and 8, the numeral 40 designates an elongated flexible 
elastomeric tubing for conveying a flux-cored welding wire from a wire 
reel source to the welding gun 10. The tubing 40 has operatively mounted 
on the leading end thereof, a connector fitting 41 which has a threaded 
attachment end 42. As shown in FIG. 8, the connector fitting threaded 
attachment end 42 is mounted through a hole 44 in an electrode lead or 
power cable lug, generally indicated by the numeral 46, and into threaded 
engagement in the upper threaded end 47 of an axial bore 48 in the gun 
header 14. A suitable 0-ring 45 is mounted between the electrode power 
cable lug 46 and the gun header 14. The cable lug 46 is adapted to have 
connected thereto a conventional electrode power lead that is connected to 
a conventional welding machine power source. An elongated coil spring 
liner 49 is mounted in the tubing 40. The tubing 40 has operatively 
mounted on the trailing end thereof a suitable fitting 50 for attachment 
to a flux-cored wire supply reel source. The numeral 52 designates a 
conventional flux-cored welding wire which is conveyed through the spring 
liner 49, and it extends downwardly from the lower end of the electrically 
conductive contact tip 37, as for example, approximately 1/2 inch, during 
the operation of the welding gun 10. The flux-cored wire 52 is supplied 
from a conventional welding wire supply reel. The flux-cored wire 52 is 
conveyed into the welding gun 10 through the axial bore 48 in the gun 
header 14, and then through the cylindrical passage 53 in the inner barrel 
11, and then through stepped bore 33 of the gas diffuser sleeve 16, and 
finally through the axial bore 54 in the electrically conductive contact 
tip 37. 
As shown in FIG. 4, the header 14 is provided with a transverse bore 58 
that communicates at its inner end with the axial bore 48 in the gun 
header 14 and which has a threaded outer end 59 for threadably mounting 
therein a threaded connector outlet of a conventional shielding gas hose 
gas hose connector fitting 60 (FIG. 2). The gas shielding connector 
fitting 60 is provided with a threaded inlet end 61 for threaded 
attachment to the outlet end of a shielding gas hose 62, for supplying an 
inert shielding gas, as for example argon gas, to the welding gun 10. The 
shielding gas passes downward through the passage 53 through the inner 
barrel 11, the stepped bore 33 through the gas diffuser sleeve 16, and 
into the axial bore in the gas diffuser 30 and out of a plurality of 
radially disposed gas diffuser ports 63, formed around the periphery of 
the gas diffuser 30. The gas nozzle or diffuser 30 delivers the shielding 
gas to the axial bore 38 formed through the water cooled cup chamber 
sleeve 26 and to the weld area around the electrically conductive contact 
tip 37 in a smooth and unrestricted manner. The gas diffuser or nozzle 30 
is made from copper, since copper is a very good heat conductor, and a 
copper nozzle resists melting when exposed to the heat generated in a 
welding operation. The electrically conductive contact tip 37 is also made 
from copper. 
As illustrated in FIG. 2, coolant water is conducted from a suitable source 
of coolant water by a conventional coolant water inlet hose 66. The 
coolant water inlet hose 66 is threadably connected to a threaded inlet 
end 68 of a brass water inlet fitting 67. The water inlet fitting 67 has a 
threaded outlet pipe 69 which is threadably mounted in the water inlet 
bore 70 (FIGS. 4, 8) in the gun header 14. As shown in FIGS. 3 and 8, the 
coolant water entering the gun header 14 flows through the longitudinal 
inlet passage 71 in the gun header 14 and thence into an elongated water 
inlet pipe 72, that has its upper end communicating with the water inlet 
passage 71 in the gun header 14, and its outlet end 74 disposed adjacent 
the lower end of the inner gun barrel 14, and into the lower or bottom end 
of the cylindrical space 75 formed between the inner gun barrel 11 and the 
outer gun barrel 15. As shown in FIG. 8, the coolant water is forced to 
the bottom cylindrical passage 75, as indicated by the numeral 76, from 
whence it moves upwardly around the inner barrel 11 to the upper end of 
the welding gun 10, as indicated by the numeral 77. The coolant water is 
then conducted through the water outlet passage 80 in the gun header 14, 
and out a threaded water outlet bore 81 in the gun header 14, and into a 
brass water outlet fitting 82 (FIG. 2). Threadably connected to the outlet 
83 of the fitting 82 is a conventional coolant water hose 84, which is 
adapted to have its outlet end attached to the inlet end (FIG. 2) of a 
coolant water inlet tube 85 that is operatively attached to the water 
cooled copper cup assembly 23. As shown in FIGS. 6 and 8, the coolant 
water enters the coolant water inlet tube 85, and flows in the direction 
of the arrow 86 to an outlet end which is fixedly mounted, as by being 
silver soldered, in a tube opening 87 formed through a water cooled cup 
lower sleeve or tube 25. The water then flows into a cylindrical hollow 
water passage 88 that is formed around the axial bore 38 in the water 
cooled cup chamber sleeve 26. The coolant water then flows around through 
the cylindrical water passage formed by the cylindrical chamber 88 and out 
through an opening 89 (FIG. 7) in the water cooled cup lower sleeve 25 and 
into a coolant water outlet and return tube 90. As illustrated in FIGS. 2 
and 5, the coolant water return tube 90 has operatively connected to its 
upper end a coolant water return hose 91 which returns the coolant water 
to the source of the coolant water. It will be seen that the 
aforedescribed water cooling system for the inner gun barrel 11 forces the 
water to start at the bottom of the elongated water inlet tube 72, which 
conducts the inlet water down to the area 75 in the lower end of the inlet 
barrel 11, from whence coolant water flows back upwardly around the inner 
tube 11 so as to create a flow through the welding gun that does not allow 
the water to stagnate and heat up. The structure of the water cooled gas 
cup 23 ensures an optimum coolant water flow, and metal thickness, at the 
end of the cup, so that physical abuse of the cup 23 does not affect its 
performance. 
In use, the welding gun 10 is disposed in a vertical position, as shown in 
FIGS. 1, over a workpiece generally indicated by the numeral 94, which is 
operatively supported on a workpiece stand generally indicated by the 
numeral 95. The welding gun 10 is operatively supported by a gun support 
apparatus, generally indicated by the numeral 96. A suitable gun support 
apparatus is one available on the market from the Weld Mold Company, of 
750 Rickett Road, Brighton, Mich. 48116-0298 under the title of "Wire 
Manipulator". The gun support apparatus 96 is shown schematically in FIG. 
1, and it generally includes a wire supply reel or wire spool 97, a 
control system to control the wire feeding speed of the flux-cored wire 52 
and the flow of shielding gas. The numeral 99 generally designates the gun 
attachment structure employed in the wire manipulator. The numeral 100 
generally indicates the gun movement controls employed in the gun support 
apparatus 96. The numeral 101 generally indicates the gas, flux-cored 
wire, electrode power lead, and coolant water tubes or lines. The movement 
of the welding gun 10 is controlled by the operator through the gun 
movement controls, generally indicated by the numeral 100.