Abstract:
A dual-electrode arc welding apparatus includes a body assembly adapted to be coupled to a source of electric power and directing two wire electrodes through a nozzle assembly to an associated workpiece at a working end of the apparatus. The body assembly is provided at a distal end with an adapter which channels the electrodes respectively through passages of a tip assembly in electrical contact with the adapter and the body assembly for conducting electric power to the electrodes. The tip assembly is removable from the adapter without removing the nozzle assembly and, upon removal of the nozzle assembly, the adapter is removable from the body assembly. The tip assembly may include a single tip body with dual passages therethrough or two discrete tips separately mounted on the adapter by either threaded engagement therewith or by being slidably received in externally threaded nipples and secured by collet nuts. Similarly, the adapter may be collet-mounted or threadedly engaged with the body assembly. Devices both with and without provisions for shielding gas are disclosed and fluid-cooled nozzle assemblies and body assemblies are disclosed. In certain embodiments, the electrodes are powered from separate power sources respectively connected to electrically separated first and second body members of a body assembly. The nozzle assembly may be removably mounted directly on the body assembly or on a docking body which is, in turn, removably mounted on the body assembly.

Description:
BACKGROUND 
     This application relates to welding apparatus and systems and, particularly, to arc welding systems such as Metal Inert Gas (“MIG”) arc welding systems. 
     Typically, a MIG welding system includes a welding gun or torch assembly which feeds a consumable wire electrode through a current pick-up tip which applies welding potential to the electrode. The gun or torch assembly includes a main housing to which is removably mounted a welding nozzle which surrounds the welding tip and may channel an inert shielding gas to the welding arc. The nozzle assembly may be air or water cooled. The welding gun or torch assembly must be serviced with the utilities which it requires for operation, such as water for cooling, gas for shielding the welding arc and electricity to effect the welding, as well as being provided with the consumable wire electrode. All of these utilities are fed to the welding gun or torch assembly from associated supplies via utilities delivery means, which may include a portable utilities station of the type disclosed in my U.S. Pat. No. 4,210,796. 
     When the welding system is to be utilized in mechanized or automated applications, the welding torch assembly is in the form of a machine barrel which is fixedly mounted on the automated welding control equipment. For example, the machine barrel may be mounted on a permanent fixed mount to which workpieces are delivered for welding or, alternatively, might be mounted on a movable mount, such as that of a robotic welding machine, which moves to the workpiece under remote control, and which may be pre-programmed. 
     It is known to provide nozzles and welding tips in such welding systems which are easily replaceable without disconnection of the systems from utilities supplies, arrangements of this type being disclosed, for example, in my U.S. Pat. Nos. 4,600,824 and 4,582,979. 
     In certain types of MIG welding applications, it is desirable to utilize two separate electrodes, and it is known to provide such dual-electrode or twin welding devices. However, heretofore, such dual-electrode devices have not afforded easy removability and replaceability of parts without requiring disconnection of utility supplies, as was afforded in the single-electrode devices of my aforementioned patents. 
     Furthermore, it is sometimes desirable to operate the two electrodes of a dual-electrode welding apparatus from two different power supplies, referred to herein as a “tandem” arrangement, and prior systems have not adequately provided for this. 
     SUMMARY 
     This application discloses an arc welding apparatus which avoids the disadvantages of prior apparatuses while avoiding additional structural and operating advantages. 
     An important aspect of the invention is the provision of a dual-electrode arc welding apparatus which includes a current-pickup tip assembly which can be simply and easily removed and replaced without affecting any utilities supplies. 
     A further aspect is the provision of a welding apparatus of the type set forth, which permits removal of the tip assembly without affecting the position of the remainder of the apparatus. of the type set forth which utilizes different types of removable tip assemblies. 
     A still further aspect is the provision of an apparatus of the type set forth, wherein the tip assembly is coupled to the apparatus via an adapter which is also removably mountable independently of a surrounding nozzle assembly. 
     Yet another aspect is the provision of an apparatus of the type set forth, wherein the two electrodes are respectively provided with separate power supplies. 
     Certain ones of these and other aspects may be attained by providing, in an arc welding apparatus for delivering two wire electrodes to a workpiece and including a body assembly adapted to be coupled to a source of electric power and directing the electrodes toward a working end of the apparatus, and a nozzle assembly removably coupled to the body assembly for channeling other utilities to the working end, the improvement comprising: an adapter electrically and mechanically coupled to the body assembly for receiving the electrodes therefrom and maintaining the electrodes spaced from each other, and a tip assembly removably mounted on the adapter in electrical connection therewith and defining two channels for respectively slidably receiving and electrically contacting the electrodes and guiding them to the associated workpiece, whereby the tip assembly is removable from the apparatus without removing the nozzle assembly or the adapter. 
     Other aspects may be attained by providing a body assembly with first and second discrete bodies electrically insulated from each other and respectively connected to separate power supplies. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For the purpose of facilitating an understanding of the subject matter sought to be protected, there are illustrated in the accompanying drawings embodiments thereof, from an inspection of which, when considered in connection with the following description, the subject matter sought to be protected, its construction and operation, and many of its advantages should be readily understood and appreciated. 
     FIG. 1 is a rear perspective view of a dual-electrode or twin arc welding torch assembly in the form of a machine barrel adapted for robotic mounting; 
     FIG. 2 is a view in horizontal section through the assembly of FIG. 1; 
     FIG. 3 is a view in vertical section through the assembly of FIG. 1; 
     FIG. 4 is a side elevational view of an arc welding gun assembly; 
     FIG. 5 is a view in partial vertical section of the gun assembly of FIG. 4; 
     FIG. 6 is an enlarged, fragmentary, rear perspective view of the gun assembly of FIG. 5; 
     FIG. 7 is a view similar to FIG. 3 of another embodiment of machine barrel assembly; 
     FIG. 8 is a view similar to FIG. 2 of the machine barrel of FIG. 7; 
     FIG. 9 is a view similar to FIG. 5 of another embodiment of arc welding gun assembly; 
     FIG. 10 is a view similar to FIG. 5 of still another embodiment of arc welding gun assembly; 
     FIG. 11 is a rear perspective view of a dual-electrode arc welding machine barrel assembly powered by two separate power supplies; 
     FIG. 12 is an enlarged view in horizontal section through the machine barrel assembly of FIG. 11; 
     FIG. 13 is an enlarged view in vertical section through the machine barrel assembly of FIG. 11; 
     FIG. 14 is a further enlarged, exploded, fragmentary, bottom plan view of a portion of the machine barrel assembly of FIG. 13; 
     FIG. 15 is a sectional view taking generally along the line  15 — 15  in FIG. 13; 
     FIG. 16 is a sectional view taking generally along the line  16 — 16  in FIG. 13; and 
     FIG. 17 is a view in partial section of a dual-electrode welding gun assembly powered by two separate power supplies. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIGS. 1-3, there is illustrated a MIG welding machine barrel, generally designated by the numeral  20 , designed for mounting on a robotic welder, at which the machine barrel  20  is provided with welding utilities, including two wire electrodes  16  and  18 , respectively provided with flexible support liners  17 ,  19 , in a known manner. The machine barrel  20  is also provided with a connection to a suitable electric welding power source, the machine barrel  20  serving to deliver the welding power to the electrodes  16 ,  18 . The machine barrel  20  is designed for use with an arc shielding gas and is fluid-cooled and, therefore, the utilities provided also include a source of shielding gas and cooling fluid, typically water. 
     The machine barrel  20  has a cylindrical housing  21 , formed of a suitable electrically insulating material and having provided at one end thereof an externally threaded collar  22  for connection to a nozzle assembly  40 . Mounted within the housing  21  is a body assembly  23  which includes a cylindrical body spool  24  fixedly secured in position at the forward end of the housing  21 , as by a mounting screw  25 . The body spool  24  has formed therethrough a plurality of passages for receiving and passing therethrough the various utilities, in a manner generally described in my aforementioned U.S. Pat. Nos. 4,582,979 and 4,600,824, although it will be understood that the specific sizes and routings of the passages will vary to accommodate the particular utilities used and to accommodate the fact that the machine barrel  20  utilizes two electrodes. More specifically, the body spool  24  has formed therethrough a stepped central bore  26 , in the rear end of which is fixedly secured the forward end an electrode fixture  27 , which has two discrete passages  28  formed therethrough for respectively receiving the support liners  17  and  19  and their respective electrodes  16  and  18 , the liners being respectively locked in position, as by set screws  29 . 
     Forwardly of the fixture  27 , the central bore  26  receives a liner support  30  provided with fittings  31  at its forward and rearward ends supporting therebetween a pair of parallel tubes  31   a,  respectively communicating with the forward ends of the passages  28  in the fixture  27 . Fixed to the rear end of the body spool  24  and communicating with a water inlet passage therein is a water inlet fitting  32  adapted to be connected to an associated source of cooling water (not shown). Similarly, a water out fitting  33  is connected to a water out passage of the body spool  24  and is adapted for coupling to a suitable drain. Typically, the water out fitting  33  will also be provided with a suitable cable for connection to the associated source of electric power, although it will be appreciated that other types of electrical connections could be utilized. A gas fitting  34  for connection to a shielding gas supply is also connected to the rear end of the body spool  24  in communication with a gas passage therein in a known manner. 
     Secured to the body spool  24  and projecting forwardly therefrom in surrounding relationship with the liner support  30  is an inner body  35  including an inner tube  36  having an annular channel  36   a  formed in the outer surface thereof near the forward end thereof, and an outer tube  37  which closes the channel  36   a  to define an annular water chamber within the outer tube  37 . The outer tube  37  is, in turn, surrounded by a gas shell  38  having an array of circumferentially spaced holes  39  therethrough near the forward end thereof and which cooperates with the outer tube  37  for defining therebetween a gas channel which communicates with the gas passage (not shown) in the body spool  24  for channeling the shielding gas forwardly, to exit through the holes  39 , again in a known manner. 
     The nozzle assembly  40  is connected to the forward end of the housing  21  and includes a cylindrical inner body  41  which has a reduced-diameter, externally threaded forward end  42  and is surrounded with a cylindrical outer shell  43 . The nozzle assembly  40  is provided at its rearward end with a radially outwardly extending annular collar  44 . The inner surface of the inner body  41  is lined with an electrically insulating sleeve  45 . The nozzle assembly  40  is secured to the housing  21  by a cone nut  46 , which has an internal shoulder which engages the collar  44 , the nut  46  being threadedly engaged with the threaded collar  22 . Preferably, the nozzle collar  44  is spaced from the forward end of the body spool  24  by an electrically insulating, generally cylindrical collar  47 , provided with openings therethrough for receiving the inner body  35  and water fittings (not shown) on the rear end of the nozzle  40  which plug into the forward ends of the water channels in the body spool  24  in a manner described in my aforementioned patents, and also described hereinafter in connection with FIGS. 12 and 13, for delivering water to and discharging water from circulation channels (not shown) in the nozzle assembly  40 . The collar  47  serves to electrically insulate the nozzle assembly  40  from the body spool  24 , which is electrically hot. The water channels in the body spool  24  also communicate with the rear ends of channels between the inner and outer tubes  36  and  37  of the inner body  35 , the channels being defined by flats (not shown) on the outer surface of the inner tube  36  and communicating at their forward ends with the annular channel  36   a  to cool the inner body  35 . A cylindrical gas nozzle  48  may be threadedly engaged with the forward end of the inner body  41 , again in a known manner. 
     It is a significant aspect of the machine barrel  20  that there is secured to the forward end of the inner body  35  an adapter  50 , which includes a body  51  provided with a rearwardly extending cylindrical extension  52  provided intermediate its ends with a radially outwardly projecting flange  53 . The adapter  50  defines two electrode passages  54  therethrough, which are designed to respectively communicate with the tubes  31   a  of the liner support  30 . Preferably the rearward end of the extension  52  slidably fits inside the forward end of the inner tube  36  of the inner body  35 . The forward end of the outer tube  37  is externally threaded for threaded engagement with a cone nut  55  which draws the flange  53  snugly against the forward end of the inner body  35 . The body  51  of the adapter  50  is provided at its forward end with externally threaded nipples  56  and  57 , which respectively communicate with the passages  54 . 
     Secured to the forward end of the adapter  50  is a tip assembly  60  which, in this embodiment, includes two cylindrical electrical pickup tips  61  and  62  which are respectively slidably received within the nipples  56  and  57  of the adapter  50 . Preferably, these nipples are longitudinally slotted to form collets, the tips  61  and  62  being respectively secured in place by collet nuts  63  and  64  which threadedly engage the nipples  56  and  57  and radially compress them in a known manner to securely grip the tips  61  and  62  and lock them in position, so that the forward ends of the tips  61  and  62  are respectively disposed just inside the forward end of the gas nozzle  48 , as can best be seen in FIGS. 2 and 3. 
     In operation, the machine barrel  20  is slipped into a suitable support ring or the like on a robotic mount, being positioned by a positioning ring  65  received in a complementary groove in the outer surface of the housing  21  for bearing against the associated support ring and accurately positioning the machine barrel. The machine barrel is connected to the associated utilities in a known manner. The electrodes and their associated support liners are fitted into the fixture  27 , the support liners  17  and  19  being respectively stopped at the adapter nipples  56  and  57 , at which depth of insertion they are locked in place by the set screws  29 , the electrodes  16  and  18  still being slidably movable through the support liners  17  and  19  and into the tips  61  and  62  for delivery to the associated workpiece (not shown). The shielding gas exits the gas shell  38  into the rear end of the nozzle assembly  40 , where it flows forwardly in surrounding relationship with the adapter  50  and the associated electrodes for exiting the gas nozzle  48  around the electrodes  16  and  18  to shield the welding arcs in a known manner. Cooling water flows into the fitting  34 , through internal passages in the body spool  24  through suitable fittings (not shown) on the collar  44 , down a passage in the nozzle assembly  40  to the forward end where it recirculates around an annular passage and returns through another nozzle collar fitting and body spool passage to the water out fitting  33 , again all in a known manner. 
     It will be appreciated that, in the event that the tips  61  and  62  become damaged in use or otherwise need repair or replacement, they can readily be removed by simply unscrewing the gas nozzle  48  and then unscrewing the collet nuts  63  and  64 , without removing either the nozzle assembly  40  or the adapter  50 . Furthermore, if need be, the adapter  50  can also be readily removed by simply unscrewing the nozzle assembly  40  at the cone nut  46  and removing it to provide access to the cone nut  55 . It will be appreciated that the tips  61  and  62  are electrically hot and impart electrical current to the consumable electrodes  16  and  18  which pass through the tips  61  and  62  in sliding contact therewith, these electrodes being fed from associated supply reels, or the like (not shown) in a known manner. 
     Referring now to FIGS. 4-6, there is illustrated a welding gun  70  which is similar to the machine barrel  20 , except that it is designed for hand-held operation. More specifically, the welding gun  70  has a housing  71  which is similar to the housing  21  described above, except that it has a handle  72  secured thereto and depending therefrom, the handle  72  being provided with a trigger button  73  for actuating an associated switch (not shown) connected in circuit with the electrical power supply. Mounted in the housing  71  is substantially the same body assembly  23  as is described above in connection with FIGS. 1-3. However, in this case, the forward end of the inner tube  36  of the inner body  35  is internally threaded and has secured thereto an adapter  80 , which includes a body  81  with a rearwardly projecting cylindrical extension  82  threadedly engaged with the inner body  35  and secured with jam nuts  83 . The adapter  80  defines two electrode passages  84  (one shown) which respectively communicate with the tubes  31   a  in the liner support  30  of the body assembly  23 . The forward ends of the passages  84  in the body  81  are internally threaded for receiving a tip assembly  85 , which includes two current pick-up tips  86  (one shown) having externally threaded ends  88  adapted to be respectively threadedly engaged in the body  81 . Mounted on the forward end of the housing  71  is the same nozzle assembly  40  described above. 
     The operation of the welding gun  70  is substantially the same as that described above for the machine barrel  20 . It will be appreciated that either of the machine barrel  20  or the welding gun  70  could be adapted for use with either of the adapters  50  and  80  and with either the slip-in tips  61 ,  62 , or the threaded tips  86 . However, the adapter and tip arrangement illustrated in FIGS. 1-3 is preferred, since it permits installation of the adapter without rotation thereof so that the proper alignment of the passages therein with the passages in the body assembly  23  can more easily be assured. This arrangement facilitates mounting of bent or curved current tips without interfering with each other, and it also permits easier adjustment of the depth of insertion of the tips so that their distal ends can more accurately be positioned relative to the distal end of the nozzle assembly  40 . 
     Referring now to FIGS. 7 and 8, there is illustrated a welding torch assembly in the form of a machine barrel  90  which is similar to the machine barrel  20 , described above, except in this case there is no provision for shielding gas and the cooling fluid is provided only to the inner body, and not to the nozzle assembly. More specifically, the machine barrel  90  has a cylindrical, electrically insulating housing  91 , threadedly engaged at its forward end with an externally threaded collar  92 . Mounted in the housing  91  is a body assembly  93  which includes a body spool  94  secured in place by a screw  95 . Formed through the body spool  94  are two side-by-side, stepped central bores  96  in which are respectively mounted two electrode fixtures  97  and  98 , each provided with a set screw  99  for fixing in position the support liner of the associated electrode. 
     Also respectively mounted in the central bores  96  and projecting forwardly from the body spool  94  are two elongated, cylindrical inner bodies  100 , each having formed in its outer surface two diametrically opposed, longitudinally extending channels  101  and  103 , joined at their forward ends by a circumferential or annular channel  102 . Each of the inner bodies  100  is telescopically received within an outer sleeve  104  which closes the channels  101  and  102  and is fixedly secured in place, as by brazing, soldering or the like. The rear ends of the channels  101  of the inner bodies  100  are connected through internal porting in the body spool  94  to a water inlet fitting  105 , which is adapted to be coupled to a suitable water supply, while the rear end of the channels  103  of the inner bodies  100  are connected through internal porting of the body spool  94  to a water out fitting  106 , which is adapted to be connected to a suitable drain. Thus, it will be appreciated that cooling water can be circulated down the length of each of the inner bodies  100 , around its distal end and then back along its entire length. Again, electrical connection can be made through the water out fitting  106 . The housing  91  is provided with a positioning ring  109  for accurately positioning the machine barrel  90  in an associated robotic support, as described above. 
     Mounted on the forward end of the housing  91  is an electrically insulating nozzle assembly  110  having a cylindrical outer tube  111  having an internally threaded distal end  112  and provided at its proximal end with a radially outwardly projecting annular collar  113  having a central opening therethrough for receiving the inner bodies  100 , and being secured in place on the housing  91  by a cone nut  114  which threadedly engages the collar  92 . Threadedly engaged in the distal end of the nozzle outer tube  111  is a support disk  115  having openings therethrough for respectively receiving and supporting the forward ends of the inner bodies  100 . Preferably the outer sleeves  104  of the inner bodies  100  project forwardly beyond the ends of the inner bodies  100  and are internally threaded for respectively threadedly receiving current pickup tips  118 ,  119 , which may be substantially the same as the tips  86 , described above. 
     Referring now to FIG. 9, there is illustrated a welding gun  120  which is internally substantially the same as the machine barrel  90 , described above, except that instead of the housing  91  there is provided the gun-type housing  71  of FIG. 5 with its attached handle  72  and associated trigger button  73 , to provide a hand-held version of the machine barrel  90  of FIGS. 7 and 8. 
     Referring now to FIG. 10, there is illustrated a welding gun  130 , which is substantially the same as the welding gun  70  described above in connection with FIGS. 4-6, except that it utilizes a different type of adapter and tip assembly. In this case, there is provided an adapter  131  having a cylindrical body  132  which defines therein a cylindrical socket  133 , and is provided with a reduced-diameter, rearwardly extending, externally threaded cylindrical extension  134  defining two electrode passages  135  (one shown) which communicate respectively with the tubes  31   a  in the liner support  30 . The extension  134  is threadedly engageable in the forward end of the inner tube  36  of the inner body  35 , being secured in place by jam nuts  136 . The passages  135  communicate with the socket  133 , the latter receiving a cylindrical two-hole tip body  140  defining therein two parallel, side-by-side electrode passages  141  (one shown), respectively communicating with the passages  135  in the adapter  131 . The depth of insertion of the tip body  140  in the socket  133  is limited by a radially outwardly extending shoulder  142  on the tip body  140  which engages the forward end of the adapter  131 , being secured in place by a cone nut  143 , which engages external threading on the adapter body  132 . 
     Referring now to FIGS. 11-16, there is illustrated a welding torch assembly in the form of a tandem machine barrel  150  which is similar to the twin machine barrel  20  described above in connection with FIGS. 1-3, except that it is designed for powering of the two electrodes respectively with different power supplies. The welding torch  150  utilizes a housing  21   a  similar to the housing  21  of the machine barrel  20  and supports therein a body assembly  151  which includes an outer cylindrical spool  152  formed of a suitable electrically insulating material and telescopically received in the forward end of the housing  21 A. The spool  152  defines therethrough a large cylindrical central passage  153  and two parallel outer passages  154  and  155 . The central passage  153  is separated into two generally semi-cylindrical portions by an insulating divider plate  156 . An electrically insulating collar  157 , which may be formed of nylon, is fitted against the forward end of the outer spool  152  for a purpose to be explained more fully below. 
     The body assembly  151  includes two body spools  160 ,  160 A which are formed as substantially mirror images of each other and are, respectively, disposed on opposite sides of the divider plate  156  in the central passage  153  and, therefore, only one will be described in detail. The body spool  160  has an electrode passage  161  formed therethrough, as well as water passages  162  and  163  and a shielding gas passage  164  (see FIG.  16 ). 
     The body assembly  151  also includes a docking spool  165  which has formed therethrough a central electrode passage  166  and peripheral water passages  167 , each incorporating a spring-biased, normally-closed valve  168  (one shown) of the type disclosed in my aforementioned U.S. patents. Disposed in the central passage  166  are two side-by-side, electrically insulating cylindrical tubes  169 . 
     The body assembly  151  also includes two inner bodies  170  and  170 A, which are substantially identical, wherefore only one will be described in detail. The inner body  170  includes an elongated cylindrical inner tube  171  which extends through the insulating tube  169 , having a rear end extending into the associated body spool  160  and a forward end projecting well beyond the docking spool  165 . The rear end of the inner tube  171  is encircled by a cylindrical gas shell  172  which communicates with a gas passage in the body spool  160  and cooperates with the inner tube  171  to channel gas forwardly to exit through a circumferential array of openings  173  (see FIG. 14) into the insulating tube  169 . The inner tube  171  is telescopically received in a cylindrical outer tube  174  which extends forwardly from the gas shell  172  and is, in turn, received in a cylindrical insulating tube  175 . A generally cylindrical spatter disk  176  having a plurality of small-diameter gas passages therethrough encircles the inner bodies  170 ,  170 A just forwardly of the insulating tubes  175 , being retained in place by retaining rings  177 . The distal end of the outer tube  174  projects beyond the distal end of the inner tube  171  and is internally threaded as at  178 . 
     In assembly, the nylon collar  157  is fitted over the inner bodies  170 ,  170 A and up against the forward end of the housing  21 A. Then the docking spool  165  is fitted over the inner bodies  170  and  170 A and up against the nylon collar  157 . The docking spool  165  has an annular flange at its rear end which is engaged by a cone nut  179 , which is threadedly engageable with the collar  22  on the housing  21 A for securing the docking spool  165  in place. 
     Respectively fixed to the rear ends of the body spools  160  and  160 A and communicating with the electrode passages therein are wire electrode fixtures  180 ,  180 A for respectively receiving wire electrode fittings  181  (one shown) (see broken line in FIG. 13) which can be secured in place by suitable set screws. Each body spool  160 ,  160 A has a shielding gas supply line  182  coupled to a gas fitting  183  mounted in the rear of the body spool for communication with the gas passage  164 . A water inlet hose  184  is coupled to a water inlet fitting  185 , which extends through the outer passage  154  in the outer spool  152 , which in turn communicates with the water inlet passage  167  in the docking spool  165 . Another water inlet hose  184   a  is coupled via a coupler  184   b  to a water inlet fitting  185   a  on the body spool  160   a  for communication with the water passage  162  thereof. Coupled with the water passage  162  in the body spool  160  via a water inlet fitting  185   a  is an interconnect hose assembly  186  (see broken line in FIG.  13 ), which is in turn coupled through the other of the outer passages  155  in the outer spool  152  for communication with the other water passage  167  in the docking spool  165 . Water out passages  163  in the body spools  160 ,  160 A are respectively coupled to water out fittings  187  which are, in turn, coupled to a water out and electric cable assemblies  188  in a manner described above. 
     The machine barrel  50  includes a nozzle assembly  190  adapted to be mounted on or docked with the docking spool  165 . The nozzle assembly  190  includes an elongated inner tube  191  provided with an externally threaded, reduced-diameter end  192  and telescopically received within a cylindrical outer tube  193 . The rearward end of the nozzle assembly  190  is provided with a radially outwardly projecting annular collar  194  provided with rearwardly projecting water fittings  195  adapted to be respectively received in the water passages  167  in the docking spool  165  for opening the valves  168  and allowing water to flow to and from the nozzle assembly  190  for cooling same in a known manner. A tapered gas nozzle  196  is threadedly engaged with the distal end of the inner tube  191 . The nozzle assembly  190  is secured in place on the docking spool  165  by means of a cone nut  197 . Threaded current pickup tips  198  and  199  are respectively threadedly engaged with the distal ends of the inner bodies  170 ,  170 A for slidably receiving the wire electrodes and imparting electrical current thereto. 
     It is significant that each of the body spools  160 ,  160 A is provided with a water out and electric cable assembly  188  so that they can be independently connected to separate power sources. The electrical power is then transferred from the body spool  160  ( 160 A) to the associated inner body  170  ( 170 A), the pickup tip  198  ( 199 ) and thence to the associated consumable wire electrode. 
     Referring to FIG. 14, in use inlet water is received through the hose  184  and fitting  185 , which passes through the outer spool  152 , outside of the body spools  160 ,  160 A, into the nozzle assembly  190  via the upper water fitting  195 , as shown in FIG. 13, from whence it recirculates through the nozzle assembly  190  for cooling thereof. The water is then returned through the interconnect hose assembly  186  to the body spool  160 , water being fed directly to the body spool  160 A via inlet hose  184   a  and coupler  184   b.  Water exits from the body spools  160 ,  160 A via the water outlet fittings  187 . Thus, the body spools  160 ,  160 A and the nozzle assembly  190  are cooled. 
     Referring now to FIG. 17, there is illustrated a welding gun assembly  200 , which is similar to the machine barrel  150  described above in connection with FIGS. 11-16, except that the docking spool  165  is eliminated and a modified nozzle assembly  190 A plugs directly into the outer spool  152  of the body assembly  151 . The gun assembly  200  has a body housing  71   a,  which is substantially similar to the body housing  71 , described above in connection with FIGS. 4-6, having a pistol-grip handle  72  and trigger button  73 . Mounted in the housing  71 A is a body assembly  151  which is substantially the same as that described above in connection with FIGS. 11-16, except for the omission of the docking spool  165 , wherefore like parts bear like reference numerals. The nozzle assembly  190   a  is substantially the same as the nozzle assembly  190 , described above, except that it has an inner tube  191 A which is internally threaded at its distal end. The internally threaded distal end of the inner body each of the inner bodies  170  (one shown) receives a collet nipple  201  which slidably receives therein a slip-in contact tip  202 . The outer end of each of the collet nipples  201  is clamped to the associated tip by a collet nut  203  in substantially the same manner as was described above with the tips  61  and  62  in connection with FIGS. 1-3, above. A modified gas nozzle  206  is threadedly engaged with the internally threaded end of the nozzle assembly inner tube  191 A. 
     Modified water fittings  195 A of the nozzle assembly  190 A plug directly into the outer passages  154  and  155  in the outer spool  152 , for coupling directly to the fitting  185  and interconnect hose assembly  186 , respectively. Since there are no valves in this embodiment, the water supply would have to be turned off before removal of the nozzle assembly  190 A. The nozzle assembly  190 A is secured in place by a cone nut  207  which threadedly engages with the threaded collar  22  of the housing  71 A. In operation, the gun assembly  200  functions in substantially the same manner as the machine barrel  150  described above in connection with FIGS. 11-16. 
     It will be appreciated that, while each of the above-described embodiments has been illustrated using a particular one of three different types of adapter and/or tip assembly, each of the disclosed welding machine barrels or guns could use any disclosed type of adapter and/or tip assembly. 
     The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. While particular embodiments have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the broader aspects of applicants&#39; contribution. The actual scope of the protection sought is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.