Abstract:
An arc welding torch includes a current conducting mounting block which provided with an open-ended socket for receiving the mounting end of a current conducting removable and rotatable barrel having a welding tip at the free end thereof. Welding wire, inert gas and coolant are supplied to the welding tip via passageways in the block and barrel. A current carrying split collar is slidable along the barrel and adapted to be wedged between the barrel and the inner surface of the socket adjacent the open end thereof via a nut which engages threads on the block to maintain the barrel in a seated and fixed position in the socket.

Description:
FIELD OF THE INVENTION 
     The present invention relates to arc welding torches and particularly to welding torches of the Gas Metal Arc Welding (&#34;GMAW&#34;) type in which the barrel carrying the welding tip can be readily removed or rotated to any desired angular position. 
     BACKGROUND OF THE INVENTION 
     GMAW welding torches typically comprise a mounting block adapted to be manipulated by a welder&#39;s hand or a robotic manipulator, made of current conducting material such as aluminum or a copper alloy. A current conducting barrel, having a welding tip at the remote end thereof, is generally inserted into a socket formed in the block. The barrel is secured in the block by means of bolts which squeeze two sides of the block, separated by a slit, together adjacent the entrance to the socket. The mounting block transfers a consumable electrode or welding wire, weld current, inert gas and generally a coolant fluid such as water, from a stationary location, e.g., a cabinet, to the barrel. The barrel is provided with appropriate passageways or channels for conducting such materials to the welding tip. See U.S. Pat. No. 4,954,690 which describes the GMAW torch sold by the assignee of this application, M. K. Products, Inc., under the trademark Prince®. The Prince® torch does not provide a coolant liquid to the barrel. Also see U.S. Pat. No. 5,549,068 which describes another torch marketed by M. K. Products under the trademark King Cobra®. The latter torch, which is water cooled, utilizes intermediate barrel mounted to the block for holding the torch barrel. 
     Torch barrels may be straight or curved depending upon the type of welding to be accomplished and the preferences of the welder. It is often necessary or highly desirable for an operator to be able to change the angular position of a curved barrel relative to the block to accommodate a robotic manipulator or to configure the torch so that it is more ergonomically compatible to a welder&#39;s hand manipulations. 
     The barrels in both of the above prior art torches can be rotated. However, a proper tool is used to remove the cover and adjust the angular position of the &#39;690 torch. An angular adjustment of the barrel in the &#39;068 torch can be readily accomplished by hand. However, the intermediate barrel (referred to in the &#39;068 patent as the main barrel) constitutes not only an additional element, but an element that is expensive to manufacture in view of the bayonet connections (22a and 22b, FIG. 3) for the cooling water. In addition, arcing can occur between metallic collet fingers (100, FIG. 5) and the welding tip barrel mounting structure (34, FIG. 3) of the &#39;068 torch if the operator fails to insure that the collet nut 20 is rotated to its tightened stop position. 
     There is a need for an improved GMAW torch assembly which allows an operator to readily rotate a weld tip barrel (particularly of the curved type) without disturbing the feed wire, gas and coolant connections while insuring that a reliable current carrying connection between the barrel and block is maintained after the rotation has been accomplished. 
     SUMMARY OF THE INVENTION 
     A welding torch, in accordance with the present invention, includes a mounting block assembly of current conducting material, such as aluminum or a copper alloy, having a cylindrical open-ended receiving socket with a proximal end adjacent the opening and a distal interior section. The mounting block is adapted to be connected to a welding current source and includes passageways opening into the distal section of the socket for supplying welding wire, coolant and inert gas to passageways in the mounting end of a current conducting elongated torch barrel .Iadd.structure .Iaddend.inserted into the socket. .[.A.]. .Iadd.The barrel structure having a frusto-conically shaped seating portion, such as a .Iaddend.current carrying split collar .Iadd.which .Iaddend.is slidable along the outer surface of the torch barrel for insertion into and extraction from a seated position in the proximal end of the socket. Preferably the collar is carried by the torch barrel. The collar, in its seated position, is wedged between the inner surface of the proximal end of the socket and the outer surface of the barrel to carry welding current therebetween and to maintain the barrel in a fixed position relative to the block. The collar, in its unseated position, permits the torch barrel to be rotated without disturbing the wire, gas and coolant connections or removed entirely from the mounting block. A manually operable assembly, such as a nut and a cooperating threaded portion on the block allows an operator to move the collar along the barrel to its seated or unseated position. 
     The construction and features of the torch assembly of the present invention may best be understood by reference to the following description taken in conjunction with the appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view, partially broken away, of the mounting block assembly and torch barrel of the present invention; 
     FIG. 2 is an enlarged exploded view of a split collar and an insertion/extraction nut subassembly for securing the barrel to the mounting block; 
     FIG. 3 is a cross-sectional view of the mounting end of the torch barrel seated in the receiving socket of the mounting block assembly; and 
     FIG. 4 is a side elevational view, partially broken away, of the mounting block assembly with the mounting end of the torch barrel seated therein. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, a GMAW welding torch or gun is illustrated (FIG. 1) which can be manually manipulated or mounted on a robotic manipulator. The gun includes an insulated housing 10, the upper portion 12 of which encloses a current conducting mounting block 14 (shown in FIG. 3). The housing includes a lower portion which forms a pistol grip for accommodating an operator&#39;s hand and encloses an electric motor (not shown). The motor pulls a consumable wire electrode 18 via a gear drive 20 (FIG. 4), from a spool of wire carried by the gun or from a stationary location, such as a cabinet (not shown), containing a spool of welding wire and supplies of welding current, inert gas and coolant fluid. A hand operated lever 17 conventionally controls a potentiometer/switch arrangement (not shown) to operate and control the speed of the motor. Coolant fluid, generally water, is supplied to the mounting block through the power cable sheath 22 and returned to the cabinet (or a sink) through a conduit or hose, such as 24. Inert gas is supplied to the block 14 through a conduit or hose, such as 26. Power for the wire pull motor may be supplied through a cable, such as 28. The conduit 30 houses the weld wire 18. 
     The mounting block 14, along with a forwardly extending frusto-conical-barrel-mounting sleeve or collet 34, having an integral flange 34a, is bolted to the block 14 via bolts 34b. The block 14 and sleeve 34 form a mounting block assembly. Both the block 14 and the sleeve are manufactured from a current conducting material with the block generally made of aluminum and the sleeve being made of a brass or copper alloy. The block assembly is provided with a cylindrical open-ended receiving socket which includes a distal section, indicated generally by the bracket 36 in FIG. 3, and a proximal end formed by the interior of the sleeve 34. It is to be noted that while the sleeve is illustrated as a separate piece, it may be formed integrally with the block 14. The block 14 is formed with annular channels 38, 40 and 42 and passageways 38a, 40a and 42a for providing coolant fluid and inert gas to the torch barrel as will be more fully described. 
     The barrel structure includes a curved cylindrical barrel member 44 (FIG. 1) made of a suitable current conducting material such as a copper alloy, which carries a welding tip 48 at the other end. The welding tip is conventional and includes a shroud 49 surrounding a wire guide 50 through which the consumable electrode is fed to the welding site. The shroud 49 is cooled by coolant channeled through the barrel and is insulated from the current conducting barrel to eliminate arcing between the shroud and the work piece. The barrel may also be covered by an insulating sheath. Inert gas from the mounting block flows through a separate passageway in the barrel (not shown) and exits in the space between the wire guide 50 and the shroud 49. It should be noted that the barrel member may be straight instead of curved, in which case there is no need to rotate the barrel after installation. 
     The mounting end 46 of the barrel is arranged to be axially inserted into the receiving socket of the mounting block assembly as is illustrated in FIG. 3. The distal section of the receiving socket is provided with an inwardly projecting abutment 52 which registers with a shoulder 54 when the mounting end of the barrel is in seated and registered position in the socket. The mounting end of the barrel is provided with peripheral grooves 56, 58 and 60 which are aligned with the socket channels 38, 40 and 42, respectively, when the barrel is seated within the socket. 
     A passageway, within the barrel (not shown) conducts the inert gas from the channel 56 to the welding tip. Additional passageways within the barrel (not shown) conduct coolant fluid from one of the channels 58, 60 to the shroud and back to the other channel in a conventional manner. The coolant, e.g., water, circulates to the very front of the shroud or cup 49 and circulates around the shroud to cool the same and then returns back to the barrel passageways. Protrusions 61 in the shroud conduct the coolant to and from the barrel. O rings 62 extend between retaining recesses in the mounting end of the barrel and the socket wall to maintain the several fluids within their assigned channels. 
     A current conducting split collar 64.[.,.]. .Iadd.forming part of the barrel structure and .Iaddend.made for example of a brass or copper alloy, cooperates with the mounting block sleeve or collet 34 to secure the mounting end of the barrel in the block assembly socket and prevent relative movement therebetween. The collar 64 has a substantially cylindrical inner surface and an outer surface which tapers at a small angle within the range of about 1° to 5° and preferably about 2° toward the insertion end 64b as is illustrated in FIG. 3. The taper, designated by the bracket 64b in FIGS. 2 and 3.[.,.]. .Iadd.forms a frusto-conical shaped seating surface which .Iaddend.mates with a corresponding .Iadd.frusto-conical .Iaddend.taper on the inner surface 34d of the sleeve 34. The cylindrical inner surface of the collar is arranged to slide axially along the outer surface of the mounting end 46 of the torch barrel 44. The collar 64 is arranged to be carried by the barrel .Iadd.and forms a portion of the barrel structure.Iaddend., although it could be carried and remain a part of the mounting block assembly. 
     The collar 64 is provided with an outwardly projecting flange 64c and a snap ring receiving groove 64d into which a snap ring 68 is arranged to be seated. A collar-insertion/extraction nut 70 cooperates with the externally threaded forward end 34c of the sleeve 34 to insert and extract the split collar from a seated position in the sleeve as will be explained more fully. 
     The insertion/extraction nut 70 includes an inwardly projecting shoulder 70a which is captured between the flange 64c and the snap ring 68. A knurled cap 72 made of insulating material is press fitted over the nut 70. 
     The torch is assembled by inserting the mounting end of the torch barrel, with the insertion/extraction nut 70 (including cap 72) and collar 64 positioned thereon, into the receiving socket of the block assembly until the shoulder 54 engages the socket abutment 52. The collar 64 and nut 70 are then slid along the barrel until the nut engages the threads on the sleeve 34. When the barrel has been turned, to provide the desired angular relationship between the mounting block assembly and the weld site or workpiece, the nut 70 is driven along the threads on the sleeve until the barrel is firmly secured in the block assembly. In the secured or seated position, the collar is wedged between the outer surface of the barrel and the inner surface of the sleeve 34 to prevent relative movement between the barrel and block assembly and to provide a continuous and reliable path for the welding current. When the rotational direction of the nut 70 is reversed the shoulder of the nut engages the snap ring and pulls the collar forwardly of the sleeve 34. This action unseats the collar and allows the barrel to be rotated relative to the block assembly without disturbing the gas, wire and coolant connections since the mounting end of the barrel remains seated in the distal end of the socket. When the collar is unseated the mounting end of the barrel may also be manually removed from the block assembly. 
     There has thus been described a novel GMAW type welding torch which allows an operator or welder to rotate the torch barrel to a desired angular position without disturbing the fluid and wire connections while insuring that a reliable current path to the barrel is maintained after the rotation has been completed. Various modifications and improvements will become obvious to those skilled in the art without involving any departure from the spirit and scope of the invention as covered by the appended claims.