PATENT ABSTRACT
A welding system having a welding implement. The welding implement having a neck, a handle and a retaining nut for securing the neck to the handle. The neck being operable to convey electrode wire therethrough. The retaining nut being adapted for wrench-tightening to a threaded portion of the welding implement. An optional retaining nut operator. The optional retaining nut operator being adapted to secure to the retaining nut. The optional retaining nut operator being adapted for manual rotation to thread the retaining nut to the threaded portion of the welding implement. The optional retaining nut operator may be adapted to snap-fit onto the retaining nut. The optional retaining nut operator may include an electrically insulating material. The electrically insulating material may include a polymer.

PATENT DESCRIPTION
FIELD OF THE INVENTION 
   The present invention relates generally to arc welding systems, and particularly to a wire-feed welding system having a welding gun. 
   BACKGROUND OF THE INVENTION 
   Welding is a common manufacturing process used to join, or to separate, metal work pieces. Arc welding is a common type of welding method. An arc welding system typically comprises a power supply coupled to a welding gun or torch housing an electrode. A welding cable may be used to couple the welding gun to the power supply. A conductive cable and a clamp may be used to couple a work piece to the power supply. A circuit between the power supply and work piece is completed when the electrode is placed against, or in proximity to, the work piece, producing an electric arc between the electrode and the work piece. The heat of the electric arc is concentrated on the work piece, or pieces, to be joined. The heat of the arc melts the metal piece, or pieces. A filler material may be added to the molten metal. The molten mass cools and solidifies when the arc is removed, forming the weld. 
   There are many different types of arc welding, such as metal-inert-gas (“MIG”) welding and submerged arc welding. In MIG and submerged arc welding, a metal wire is used as the electrode. Additionally, the electrode wire may act as filler material for the weld. The wire is fed from a wire feeder coupled to the power supply. In MIG welding, the electrode wire is shielded at the point of contact by an inert gas. In submerged arc welding, a powdery flux is used to shield the electrode wire at the point of contact. The inert gas and flux shields the molten metal at the point of contact from outside contaminants and gases that may react with the molten material. Non-inert gases, such as CO 2 , also may be used in MIG welding systems. 
   The wire and gas typically are fed through a welding gun having a welding cable. The welding cable receives the wire from a wire feeder and gas from a gas cylinder. The welding cable also has additional conductors to assist the wire in conducting power from the power source. The welding gun typically has a handle and neck that are used to direct gas or flux and wire towards a work piece. A retaining nut typically is used to secure a neck to a connector coupled to the welding cable. The connector enables electricity to flow from the welding cable to an inner portion of the neck. If the retaining nut loosens, the area of contact between the neck and the connector and/or welding cable will decrease. This increases the electrical resistance between the neck and the welding cable. In some applications, such as with electrical currents above 400 amps, the increase in electrical resistance results in the production of a substantial amount of resistive heating. The heat from the resistive heating produced at the interface may heat up the handle to the point where it cannot be held. Consequently, it may be desirable to wrench tighten the retaining nut so that neck does not come loose. However, hand-tightening the retaining nut to the connector is sufficient in many applications and does not require a tool to perform. 
   There exists then a need for a method of securing a neck to a welding implement that provides an assembler with the option of configuring the welding implement for either wrench-tightening or hand-tightening a securing nut for the neck. 
   SUMMARY OF THE INVENTION 
   The present technique provides a novel technique designed to respond to such needs. According to one aspect of the present technique, a welding system is provided. The welding system comprises a welding implement having a neck adapted to convey electrode wire therethrough. The welding implement comprises an operator securable to a wrench-tightenable retaining nut to enable a user to hand tighten the retaining nut to secure the neck to the welding gun. The hand operator may be an optional attachment adapted to be disposed over the retaining nut. The hand operator may be adapted to secure to the retaining nut when disposed over the retaining nut. In one embodiment of the present technique, the retaining nut is adapted to be wrench-tightened and to enable the hand operator to be attached to the retaining nut. 
   According to another aspect of the present technique, a method of assembling a welding implement is featured. The welding implement comprises a neck secureable to the welding implement by a retaining nut. The retaining nut may be adapted to be wrench-tightened. The method may comprise disposing an operator to a retaining nut to enable a user to hand tighten the retaining nut to secure the neck to the welding implement. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and: 
       FIG. 1  is a diagram of a MIG welding system, according to an exemplary embodiment of the present technique; 
       FIG. 2  is an elevational view of a welding gun having a retaining nut, according to an exemplary embodiment of the present technique; 
       FIG. 3  is an elevational view of a welding gun having a hand operator disposed over a retaining nut, according to an exemplary embodiment of the present technique; 
       FIG. 4  is an elevational view illustrating the attachment of the neck of  FIG. 3  to the welding handle, according to an exemplary embodiment of the present technique; 
       FIG. 5  is an elevational view of a welding gun neck and retaining nut, according to an exemplary embodiment of the present technique; and 
       FIG. 6  is a cross-sectional view of the retaining nut and hand operator of  FIG. 5 , according to an exemplary embodiment of the present technique. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring generally to  FIG. 1 , an exemplary metal inert gas (“MIG”) welding system  20  is illustrated. However, the present technique also is operable with other types of welding systems, such as submerged arc welding systems. The illustrated welding system  20  comprises a combination power source/wire feeder  22 . However, a separate power source and wire feeder also may be used. The illustrated welding system also comprises a gas cylinder  24  containing a gas  26  that is coupled to the power source/wire feeder  22 . A spool  28  of electrode wire  30  also is coupled to the power source/wire feeder  22 . The electrode wire  30  and gas  26  are coupled to a welding gun  32  having a welding cable  34 . However, the present technique is applicable with welding implements other than a welding gun, such as a robotic welder. 
   In the illustrated embodiment, the welding cable  34  is adapted to receive gas  26  and electrode wire  30 . Additionally, in this embodiment, the welding cable  34  has a plurality of conductors that, along with the electrode wire  30 , couple electricity from the power source  22  to the welding gun  32 . The additional conductors prevent the electrode wire from having to carry the entire electrical current load, which could lead to failure of the electrode wire. In addition, the additional conductors reduce resistive heating losses. The work clamp  36  is clamped onto the conductive work piece  40  to be welded. The work clamp  36  and the ground cable  38  electrically couple the power source/wire feeder  22  to the work piece  40 . Additionally, the wire  30  within the welding cable  34  is electrically coupled to the power source/wire feeder  22 . The welding gun  32  is used to direct the gas and wire toward the work piece  40  and to control the supply of gas  26  and wire  30  from the power source/wire feeder  22 . 
   The electrical circuit is completed when the electrode wire  30  contacts, or is brought into proximity with, the work piece  40 . Electricity from the power source  22  flows through the electrode wire  30  and work piece  40 , producing an arc. The electric arc produces heat that melts the work piece  40  in a region surrounding the point of contact between the wire  30  and the work piece  40 . The wire  30  also acts as filler material. The heat of the arc melts the wire  30  along with the work piece  40 . The inert gas  26  forms a shield that prevents harmful chemical reactions from occurring at the weld site. When the arc is removed, the work piece  40  and the filler material solidify, forming the weld. 
   Referring generally to  FIGS. 1 and 2 , the welding gun  32  comprises a handle  42 , a trigger  44 , a trigger lock  46 , a neck  48 , a retaining nut  50 , and a nozzle assembly  52 . In this embodiment, the handle  42  comprises two handle pieces secured to each other around the welding cable  34  to form the handle  42 . The welding cable  34  also has an electrical cable (not shown) that is electrically coupleable to the trigger  44  to enable the trigger  44  to control the power source/wire feeder  22 . In this embodiment, a number of events occur when the trigger  44  is operated. One event is that the power source/wire feeder  22  draws in wire  30  from the wire spool  28  and feeds it though the welding cable  34  to the neck  48  of the welding gun  32 . Gas  26  also flows from the gas cylinder  24  flows through the welding cable  34  to the neck  48  of the welding gun  32 . 
   In addition, electricity from the power source/wire feeder  22  is supplied to the conductors in the welding cable  34  and conducted to the neck  48  of the welding gun  32 . Preferably, the neck  48  comprises copper. The nozzle assembly  52  is coupled to the opposite end of the neck  48  and is adapted to direct wire  30  and gas  26  towards the work piece  40 . In addition, the nozzle assembly  52  has a contact tip (not shown) that is adapted to conduct the electricity flowing through the neck  48  to the electrode wire  30 . The nozzle assembly  52  may also have a gas diffuser to provide optimal gas flow properties. 
   The trigger lock  46  is operable to secure the trigger  44  engaged so that a user need not actively hold the trigger  44  engaged during prolonged periods of operation. When the trigger  44  is released, gas  26 , wire  30 , and electrical power are no longer fed to the welding gun  32 . A voltage control  54  and a wire speed control  56  are provided to enable a user to vary the voltage applied to the electrode wire  30  by the power source/wire feeder  22  and the speed that the wire  30  is fed from the power source/wire feeder  22 . 
   In the illustrated embodiment, the neck  48  is secured to the welding handle  42  by threading the retaining nut  50  to a threaded portion  58  of the welding cable  34 . However, the neck  48  may be threaded to another portion of the welding gun. For example, the welding cable  34  and neck  48  may be coupled through a separate threaded connector. The retaining nut  50  is adapted to be wrench-tightened to the threaded portion  58  (see  FIG. 4 ) of the welding cable  34 . Preferably, the retaining nut  50  comprises metal. However, other materials may be used. Of the metals, brass is preferred. However, other metals, such as aluminum and steel may be used. A boot (not shown) comprised of an electrically insulating material may be disposed over the retaining nut  50 . 
   Referring generally to  FIGS. 3 and 4 , a hand operator  60 , rather than a boot, is disposed over the retaining nut  50  in the illustrated embodiment. The hand operator  60  is adapted to enable a user to hand-tighten, rather than wrench-tighten, the retaining nut  50  onto the threaded portion  58  of the welding cable  34 . Preferably, the hand operator  60  is comprised of an electrically insulating material, such as a polymer. For example, the hand operator  60  may be comprised of a glass-filled nylon or a glass-filled polycarbonate. The hand operator  60  may be secured to the retaining nut  50  by the manufacturer or provided to a customer to enable a customer to elect whether or not to install the hand operator  60 . 
   As illustrated in  FIG. 5 , the hand operator  60  is adapted to slide over the neck  48 . The neck assembly  52  may be removed to facilitate the installation of the hand operator  60 . The hand operator  60  has a plurality of indentations  62  disposed around the circumference of the hand operator  60  to enable a user to hand-tighten the retaining nut  50 . In this embodiment, the indentations  62  are curved to receive the digits of a users hand so that a user may rotate the hand operator  60 , as well as the retaining nut  50 , easily when the hand operator  60  is secured to the retaining nut  50 . In addition, the indentations  62  provide leverage to enable a user to provide force to tighten the retaining nut  50  onto the threaded portion  58  of the welding cable  34 . The retaining nut  50  is adapted with a plurality of faces  64  to enable a wrench to be used to tighten the retaining nut  50  onto the threaded portion  58  of the welding cable  34 . The neck  48  has a first end  66  that is adapted to be inserted into a portion of the welding cable  34 . The neck  48  has a second end  68  that is adapted to receive the nozzle assembly  52 . In the illustrated embodiment, to secure the neck  48  to the handle  42 , the first end  66  of the neck  48  is placed within the threaded portion  58  of the welding cable  34 . The retaining nut  50  then is threaded into the threaded portion  58  of the welding cable  34 . 
   As illustrated in  FIG. 6 , the neck  48  is adapted with a first groove  70  and the retaining nut  50  is adapted with a corresponding second groove  72 . A retaining ring  74 , such as a snap ring, is disposed within the grooves to secure the retaining nut  50  to the neck  48 . The illustrated retaining ring  74  allows the retaining nut  50  to rotate relative to the neck  48 . The retaining nut  50  also has a threaded portion  76  that is adapted for threaded engagement with the threaded portion  58  of the welding cable  34 . As the retaining nut  50  is threaded with the threaded portion  58  of the welding cable  34 , the retaining nut  50  urges the retaining ring  74 , and thus neck  48 , towards the welding cable  34 , forming a seal between the neck  48  and the welding cable  34 . 
   In the illustrated embodiment, the hand operator  60  is securable to the retaining nut  50  without the use of tools. The hand operator  60  is adapted to slide over and snap-fit onto the retaining nut  50 . The illustrated embodiment of the hand operator  60  is adapted with a plurality of fingers  78  that are adapted to flex as the hand operator  50  is slid over the retaining nut  50  and snap into a securing groove  80  in the retaining nut  50 , securing the hand operator  60  to the retaining nut  50 . In this embodiment, the fingers  78  are adapted with a catch portion  82  adapted to abut a surface  84  of the securing groove  80 . The hand operator  60  also has a rear lip  86  adapted to abut against a rear surface  88  of the retaining nut  50  to urge the retaining nut  50  towards the threaded connector  58 . The hand operator  60  also is adapted to contact the faces  64  of the retaining nut  50  to rotate the retaining nut  50  as the hand operator  60  is rotated. In the illustrated embodiment, the rear surface  88  of the retaining nut is adapted with a curved surface  90  to facilitate flexing the fingers  78  of the hand operator  60 , as the hand operator  60  is slid over the retaining nut  50 . The catch portion  82  is adapted with a corresponding angled surface to further facilitate the flexing the fingers  78  of the hand operator  60 . 
   Referring again to  FIG. 4 , the electrode wire and gas are conveyed through the neck  48  to the nozzle assembly  52 . In the illustrated embodiment, within the nozzle assembly  52  is an insulator  92 , a diffuser  94 , and a contact tip  96 . Electricity from the welding cable  34  is coupled through an inner portion of the neck  48  to the contact tip  96 . The contact tip  96  is used to conduct the electrical current from the power source into the electrode wire  30 . The contact tip  96  also is used to guide the electrode wire. The diffuser  94  is used to establish the desired flow characteristics of the gas  26 , e.g., pressure. The diffuser  94  may be connected to the neck  48  and the contact tip  96  secured to the gas diffuser  94 . The insulator  92  is used to prevent electricity in the gas diffuser  94  from flowing to the welding gun  32  through an outer portion of the neck  48 . The nozzle  52  is used to direct the gas  26  and wire  30  to the work piece  40 . 
   It will be understood that the foregoing description is of preferred exemplary embodiments of this invention, and that the invention is not limited to the specific forms shown. For example, the retaining nut and/or hand operator may be formed of different materials than described. These and other modifications may be made in the design and arrangement of the elements without departing from the scope of the invention as expressed in the appended claims.