A metal inert gas welding torch having a wire guide assembly threadably secured at one end to a torch body and a collet nut assembly threadably secured to the other end of the wire guide assembly. A spidered collet is mounted in the collet nut assembly and forms a plenum chamber with the wire guide assembly and collet nut. A contact tip is gripped by the spidered collet and extends into the plenum chamber whereby the shielding gas cools the contact tip prior to the distribution of such gas into a nozzle.

The invention relates to an electric arc welding torch. More particularly 
this invention relates to a consumable electrode metal arc gas shielded 
welding torch. 
In metal inert gas welding (Mig) a consumable electrode wire is fed from a 
source thereof through a welding torch to a point of use. Welding current 
is usually introduced into the wire through a tubular contact tip mounted 
in the torch. The industry is constantly seeking welding torches of this 
type which are simple, inexpensive to manufacture, have longer contact tip 
life and generally are easy to handle. The torch of this invention has 
these and several other desirable features as will be described 
hereinafter. 
In one aspect of this invention a torch is provided with a system for using 
the shielding gas passing through the torch to cool the contact tip. The 
relatively low contact tip operating temperature will minimize the 
tendency for weld spatter to clog the contact tip which of course requires 
replacement of the tip. The torch provides for easy replacement of the 
contact tip when it does become necessary to change the tip from excess 
spatter or from burnback of the wire into the tip. 
The torch also has an arrangement for providing better distribution of the 
shielding gas passing through the torch thus providing better gas 
shielding of the arc and weld puddle. 
Accordingly, it is an object of this invention to provide a torch which is 
simple and inexpensive to manufacture, has relatively low contact tip and 
torch handle temperatures, has a low-cost torch body, has an easily 
replaced wire guide assembly, has a relatively low-cost collet nut 
assembly and has a curved wire guide assembly with an effective locking 
means to prevent rotation and loosening during usage.

The objects of the invention are accomplished in one mode by a torch having 
a split torch handle. A torch body with a gas passage therein is fitted 
into molded slots in the halves of the split torch handle. A wire guide 
assembly is removably fastened at one end thereof to the torch body and 
has a gas passage therein communicating with the gas passage in the torch 
body. A spidered collet is fitted into a collet nut assembly, which 
includes a collet nut and an insulating nut secured together. The collet 
nut is threadably fastened to the other end of the wire guide assembly. 
The spidered collet, collet nut assembly and wire guide assembly form a 
plenum chamber for receiving gas from the gas passage in the wire guide 
assembly. A tubular contact tip is fitted into and gripped by the spidered 
collet and preferably extends into the plenum chamber so that the 
shielding gas passing through the torch will pass in direct contact along 
at least a portion of the contact tip. The spidered collet can be 
tightened around the contact tip by threading the collet nut on the wire 
guide assembly. An insulated nozzle is secured to the collet nut assembly 
and receives gas from the spidered collet after it passes along the 
contact tip. 
Having described the invention in general terms reference will now be made 
to the drawings which illustrate a preferred embodiment of the invention. 
Referring to FIG. 1 the torch "T" has a torch body 1 fitted into slots 
molded into the torch handle 3 which is split into two halves 3a and 3b 
(see FIG. 2). The torch body 1 has a gas and wire passage 5 therein for 
receiving gas and wire from a source of each through a common conduit. 
Threadably fastened to the torch body 1 is a curved wire guide assembly 7. 
Preferably a pipe thread is used to connect assembly 7 to torch body 1 as 
will be described in more detail hereinafter. The wire guide assembly 7 
has a gas and wire passage 9 communicating with gas and wire passage 5 in 
the torch body. See FIG. 3. The gas and wire passage 9 terminates at a 
centering bushing 11, located in the wire guide assembly 7. Centering 
bushing 11 which is closely fitted to a continuous wire liner 10 located 
in gas and wire passage 9 which extends all the way back through the gas 
wire passages 9 and 5 to the wire feeder. The centering bushing is 
preferably made from pinion stock. Threadably secured to the end of the 
wire guide assembly 7 is a collet nut assembly 13. Collet nut assembly 13 
includes a collet nut 14 and an insulating nut 15. The collet nut is 
secured to the insulating nut by crimping at point 16. A collet 17 is 
mounted in collet nut 14. Collet 17 has a plurality of sections 18 forming 
a spidered portion. The sections 18 terminate in tapered portions which 
mate with tapered portions of the wire guide 7 at point 19. The 
arrangement permits the spidered collet 17 to be tightened about contact 
tip 12 by threading insulating nut 15 of a collet nut assembly 13 on wire 
guide assembly 7. The wire guide assembly 7 and centering bushing 11 
therein forms a plenum chamber 20 with the spidered collet 17. An 
insulated nozzle assembly 21 is secured to the collet nut 14 by a hose 
type clamp 22. 
As mentioned above the spidered collet 17 is actuated by the collet nut 14 
and insulation nut 15 (collet nut assembly 13). Because of the way the 
collet 17 is mounted in the collet nut 14, the collet 17 is free to turn 
in the collet nut and against the tapered ends of the wire guide assembly 
7. This permits the collet 17 to seat against the wire guide assembly 7 in 
the most favorable position and with a minimum twisting of the section 18 
of the collet. This feature accommodates slight eccentricity and 
misalignment of mating parts. The results are improved gripping of contact 
tip 12 and increased heat transfer from contact tip 12 to the collet 17 to 
the wire guide assembly 7. 
Feeding wire through the torch is improved by the continuous spiral liner 
10 that extends from the wire feeder to the centering bushing 11. The 
close fit between the outside diameter of the liner about 0.186 inches and 
the inside diameter about 0.190 inches of the center bushing provides 
excellent centering and alignment of the wire as it enters the contact tip 
12. This combination also permits reliable self threading of the wire 
through the torch. 
The close fit between the centering bushing 11 and the liner 10 
necessitates additional area for gas flow. This is accomplished by the 
passages 23 between the external flutes of the pinion stock that is used 
for the centering bushing and the inside diameter of the curved wire guide 
assembly 7. The gas then flows into the chamber 20 between the collet and 
the centering bushing. This chamber equalizes gas pressures and thereby 
improves gas shielding. 
An objective of the split handle design is to provide easy assembly and 
disassembly and repair of internal parts. Assembly is very easily 
accomplished. For example, one-half of the split handle is placed on a 
flat surface. The assembled curved wire guide assembly 7, with the wire 
guide insulator 25, therearound, the torch body 1 and the service lines 
are placed into cavities 34 molded into the handle which fit these parts. 
A quick disconnect switch 26 is placed over the two pins 27 that are 
molded into the handle. The cylindrical pivot portion 28 of the torch 
switch lever 29 fits into a mating cavity in half of the torch handle. The 
other half of the handle is then positioned and the two handle halves are 
held together by means of the hose clamps 30 and 31, one at each end of 
the handle. 
The torch body 1 is made from hex stock. The hex shape provides important 
wrench flats for use during assembly and disassembly. The projection 32 of 
wire guide assembly 7 in combination with set screw 33 in the torch body 1 
and the substantial lock force provided by using pipe threads between the 
body 1 and assembly 7 provide an effective joint that does not loosen or 
have a high voltage drop. The pipe thread is similarly effective for the 
torch body to service line connection. 
Having described the invention with reference to a preferred embodiment, it 
should be understood that modification may be made to certain parts and to 
the arrangement of such parts without departing from the spirit and scope 
of the invention.