Abstract:
An arc welding torch having a variable electrode receiving aperture including a number of discrete wedges guided within a conical interior surface of a housing to enable the use of electrodes of various diameters without changing components of the torch. An adjusting collar engages the wedges and forms an adjustable opening for an electrode to be inserted therein. Rotation of a tailpiece of the torch handle adjusts the position of the wedges and secures the electrode in position.

Description:
This application claims priority under 35 USC 119(e) from U.S. Provisional Patent Application No. 61/333,945, filed May 12, 2010, by Jesse Rogers, which is hereby incorporated by reference in its entirety. 
    
    
     A self-centering adjustable electrode receiver, for a gas shielded welding torch, includes a plurality of electrode securing wedges that are coordinated to uniformly contact electrodes of various shapes, diameters, lengths and orientations. The adjustable wedges provide a robust and uniform contact with the electrode and thus reduce the likelihood of resistive heating in the contact region. Premature wear of the threads and the internal surfaces of conventional collets, will also be averted by eliminating a multitude of changeovers, as well as the loss or misplacement of unused collets. 
     BACKGROUND AND SUMMARY 
     Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is an electrical welding process that uses the arc from a tungsten electrode to produce heat sufficient to create a plasma “puddle” to weld or fuse work pieces together. TIG welding can be used for a number of materials and alloys and is thus a very versatile welding process. However, the welding parameters and electrode sizes are often adjusted based upon the material being welded. For example, the diameter of the non-consumable tungsten electrode can vary between about 0.5 mm and about 6.4 mm (0.020 in.-0.25 in.) depending upon the workpiece material and type of weld, and the length of the electrodes can range from about 75 mm to about 610 mm (3 in.-24 in.). 
     The weld area is protected from atmospheric contamination by an inert shielding gas, such as argon. A welding power supply provides an electrical current that, upon creation of an arc between the electrode and the material being welded, produces concentrated thermal energy sufficient to weld the piece(s). The focused heat is sufficient to place the contact area, as well as an optional filler rod, into a plasma state. Air cooling systems are most often used for low-current operations, however water cooling is generally required within the torch head for a majority of TIG welding systems in order to dissipate heat in higher current applications or in applications requiring longer duty cycles. 
     Tungsten arc welding gas shielding torches employ dedicated collets and collet bodies for holding only one specific diameter electrode within the torch head. Electrode collets are typically made from copper in a tubular shape and have at least two longitudinal gaps or slots to allow the diameter of the collet to be radially compressed when moved in relationship to the interior conical shape of an adjacent collet body. This compression of the collet minimally reduces the opening therein to engage and secure the electrode within the nominal internal radial area of the collet. Since the collet is compressed against the electrode over a relatively small area, the current density per unit area is significant and substantial heat may be generated due to the electrically resistive connection to the electrode, which also may perpetuate peripheral arcing within the collet. Accordingly, the electrode, as well as the collet, has a tendency to erode over time due the effect of repetitive expanding and contracting caused by both the resistive and conducted heating and subsequent cooling. The situation is further aggravated due to the copper collet having a coefficient of thermal expansion of 9.8×10 −6  in/in/° F., whereas the tungsten electrode only expands about half as much (3.9×10 −6  in/in/° F.), thereby potentially causing a loose fitting electrode while welding, potentially further increasing the electrical resistance and/or causing the electrode to become unstable and to move within torch head. 
     Collets and collet bodies are provided in at least six aperture sizes to accommodate various diameters of the job specific electrode. Therefore a significant limitation of the existing collets is that each electrode size requires a specific corresponding collet and collet body. Consequently, each time an alternate electrode diameter is required, the collet assembly must be interchanged as well. For example, it is required to have on hand at least one 1/16 inch collet and collet body to accompany a 1/16 inch tungsten electrode, as well as a ⅛ inch collet and collet body for a ⅛ inch electrode, and so forth. This unfortunately becomes a logistical challenge, as well as a time consuming exercise each time the electrode is interchanged for another size. Moreover, the use of collets prevents the reversal of electrodes that may develop a bead or enlarged end. 
     When an electrode comes in direct contact with a work piece the tip becomes contaminated when “foreign” metal that is transferred and adheres to the tip of the tungsten electrode. This added material produces a mushrooming of the tip and requires the electrode to be either reground or replaced. The use of an adjustable electrode receiver as disclosed herein, however, provides a sufficient opening or adjustability for the mushroomed end of the electrode to be flipped, end for end, and reinserted as the enlarged and contaminated end is passed through the adjustable opening. Thus, it is a further objective to provide an electrode receiver that will allow insertion of the expanded/contaminated end therethrough, and thereby avoiding a problem with the use of sized collets to hold electrodes. 
     The internal metal parts of a torch are preferably made of copper or brass in order to conduct electrical current and transfer heat with minimal resistance across a relatively small contact area. The body of the torch is made of heat-resistant, insulating plastics and similar materials for both covering the metal components as well as providing insulation from heat and electricity to protect the welder. Additionally, provisions may be provided to allow a constant flow of the shielding gas to pass through the torch handle and electrode receiver to the work piece area in order to provide an inter gas atmosphere in proximity to the weld. 
     In the interest of versatility and convenience, a welder should be enabled to select and use any size electrode at anytime, to effect optimal welding, without the need to reconfigure the electrode receiver within the torch head. In other words the configuration of the torch head and associated housing should not dictate the size or shape of an electrode. Therefore, an adjustable electrode receiver, that can be varied as needed to accommodate a variety of different size electrodes, provides a distinct advantage when using an electric welding torch, such as the case with TIG welding. 
     The embodiments disclosed herein are directed to an improved torch with an adjustable or variable electrode receiver that eliminates the need for collets in order to enable use of a plurality of electrode sizes. In the improved torch a plurality of electrically conductive, adjustable wedges are employed to provide an adjustable electrode aperture through which electrodes of various sizes, and shapes, may be placed and held. 
     In accordance with one aspect of the disclosed embodiments, there is provided an electric arc welding torch having an adjustable electrode receiver, comprising: a plurality of radially positioned electrode securing wedges forming an aperture therebetween; an internal conical surface, each securing wedge traversing, in unison in a longitudinal direction to form a variable aperture therebetween; an electrode passing through said variable aperture in contact with each securing wedge, said securing wedges further providing electrical contact between the electrode and the conical surface; and an adjusting collar positioning the securing wedges longitudinally along the internal conical surface, said adjusting collar forcing said wedges into secure contact with the electrode, wherein the aperture is adjustable for use with a range of electrode diameters. 
     In accordance with another aspect of the disclosed embodiments, there is provided a method for using a welding torch in combination with an arc welder, comprising: providing an adjustable electrode receiver having a plurality of electrically conductive wedges defining an aperture therein, said aperture being suitable for receiving a plurality of electrodes of different diameters; inserting a first electrode into the aperture in the electrode receiver; adjusting the wedges to be in electrical contact with an outer surface of the first electrode; and securing the first electrode in a fixed position using the wedges by applying a force to said wedges via a threaded collar in contact with the first electrode. 
     In accordance with a further aspect of the disclosed embodiments, there is provided A welding system, comprising: a power supply; an inert gas supply; and a welding torch electrically connected to the power supply and coupled to the inert gas supply, said torch including an adjustable electrode receiver suitable for receiving a plurality of electrodes of different diameters. 
     Other and further objects, features and advantages will be evident from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein the examples of the presently preferred embodiments are given for the purposes of disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a TIG welding system, employing the welding torch having an adjustable electrode receiver; 
         FIG. 2  is a cut away view of the torch handle of the system in  FIG. 1 ; 
         FIG. 3  is an assembly view of the components within the housing of the torch head of  FIG. 2 ; 
         FIGS. 4A and 4B  are, respectively, a cross-sectional side and an end view of a gas manifold of the welding torch; 
         FIGS. 5A and 5B  are, respectively, an end view and a planar view of an exemplary electrode securing wedge; 
         FIGS. 6A and 6B  are, respectively, a top and a planar view of a wedge guide housing depicting a conical surface therein; 
         FIGS. 7A and 7B  are, respectively, an end and a planar view of the wedge actuator or adjusting collar; and 
         FIG. 8  is an exploded assembly view of the electrode receiver assembly in accordance with the disclosed embodiments. 
     
    
    
     The various embodiments described herein are not intended to limit the invention to those embodiments described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the welding torch and adjustable electrode receiver as defined by the appended claims. 
     DETAILED DESCRIPTION 
     Referring now to the drawings where the showings are for the purpose of illustrating a preferred embodiment of the electrode receiver. 
     The system of  FIG. 1  includes several elements of a gas tungsten arc welder. In one embodiment welding system  100  includes a power supply  102 , inert gas supply  104 , water/liquid cooler  106  and torch assembly  200 . In practice, workpiece  108  is electrically connected to power supply  102  to provide either −DC, +DC or AC through clamp and return cable  110  to workpiece  108 . Torch  200  provides means for delivering the inert gas as well as an arc formed within an air gap between the tip of the tungsten electrode and the work piece  108 , to generate the heat required to fuse the work pieces together. Torch  200  is further connected to a water or chilled liquid supply for cooling when a high current and/or extended duration welding operation is performed. 
     Also considering  FIGS. 2 and 3  in combination with  FIG. 1 , torch  200  is shown comprising three discrete inputs, water  226 , inert gas  224 , and electrical current  230  which may be connected to the torch within handle region  112 . Also disclosed with respect to a conventional torch handle design, it will be appreciated that various aspects of the disclosed electrode receiver and aperture may indeed be used in or applied to alternative welding torch configurations, such that he shape and configuration of the torch itself may preferably take different forms. 
     The operative mechanical elements of the electrode receiver within a housing of the torch  200 , particularly the torch head  201 , include at least two wedges  206 , within the interior conical surface of wedge guide housing  208 . The electrode securing wedges  206  are maintained in forcible contact with electrode  204  by wedge actuator  212 . Manifold  114  provides a channel for inert gas to be released with a shroud  210  to concentrate the inert gas in the region of the arc extending between the work piece  108  and the electrode  204 . The end of the torch head typically includes a tailpiece  216  that encloses that portion of the electrode  204  extending through the head  201 . 
     With respect to  FIG. 3 , torch  200  is shown in an exploded view where electrode  204  is inserted along the interior surface of wedges  206  and clamped therein by a force applied to the ends  207  by an actuator or adjusting collar  212 . In the depicted embodiment, the force is provided by tailpiece  216  being rotated and a threaded surface of mating member  212  being advanced or retracted in response to the rotation of the tailpiece. It will be further appreciated that a circulating collar  228  or similar means for cooling the components of the torch head  201  is provided in association with the handle/housing via lines passing through housing  249 . 
     As specifically illustrated in  FIGS. 4A-7B , each of the operative elements of the electrode receiver embodiments will be further described.  FIGS. 4A and 4B  represent a gas manifold  114  having radial positioned ports  116  for the channeling of an inert gas, such as helium or argon, into the work area. As illustrated in  FIGS. 5A and 5B , depicting an exemplary one of three electrode securing wedges  206 , each of the wedges are positioned and slide within channels formed along the interior conical surface  217  of wedge guide housing  208  as depicted in  FIGS. 6A and 6B . Wedges  206  may be made from any electrically conductive material, such as a #660 bronze or similar metal. In one aspect the wedges have a profile generally taking the form of a right triangle with a protruding shoulder or guide key  219  extending along the hypotenuse. The guide key of wedges  206  have corresponding keyways within guide housing  208  to provide consistent alignment between wedge actuator  212  and electrode  204 . Wedges  206 , together with housing  208 , are caused to tighten about electrode  204  by wedge actuating or adjusting collar  212 , as depicted in  FIGS. 7A and 7B , as a result of rotating tailpiece  216  in a clockwise direction. Rotation of the tailpiece causes the displacement of actuator collar  212 , which in turn translates wedges  206  along the interior inclined conical surface  217  of wedge guide housing  208 . 
     Resilient members such as compression springs  218  provide a force onto or between wedges  206  sufficient to cause the wedges to move up the ramp or conical surface of wedge housing  208  when actuator  212  is backed off in order to increase the diameter of the electrode opening. It will be further appreciated that while the springs  218  are depicted as lying between adjacent wedges  206 , or more particularly, recesses  223  on angled surfaces of the wedges, it is also possible to provide other wedge and spring configurations that bias the wedges to tend to move outward (and therefore upward within the housing  208 ). 
     Notably, the rate of change of the orifice diameter formed by anterior surface of wedges  206  is a function of the pitch of the thread, or turns per inch (TPI) on wedge actuator  212 , as well as included angle Θ ( FIG. 6B ) or slope, of the posterior surface of the hypotenuse of wedge  206 . Accordingly, the corresponding interior conical surface of wedge guide housing  208  share a common slope angle, typically in the range of 15-20 degrees. This pair of co-sliding planes further serves to maintain parallelism between the interior surface of wedges  206 , thereby providing an uniform contact region along electrode  204 . Consequently, the minimum and maximum aperture diameter (D) is a function of the sine of angle Θ. For example, if the wedge angle is 17 degrees and the operating length of the inclined side is 0.5 in, the wedge range of motion will be y=(x) (sin Θ) or y=(0.5 in)(0.29)˜=0.145 in, therefore the max aperture opening would be twice y, or about 0.290 in., which would readily accommodate each of the diameters of the aforementioned electrodes. 
     Generally referring now to  FIG. 8 , the relationships of the various constructive elements of the electrode receiver are depicted in an exploded view. The distal and proximal ends of electrode receiver  201  allow for an electrode to pass completely therethrough, providing a torch handle that is independent of electrode length, or diameter. As previously noted, electrode  204  (not shown in  FIG. 8 ) passes into the center of the gas manifold  114  and entirely through the length of electrode receiver  101  to the proximal end within tailpiece  216 . 
     In recapitulation, as illustrated in the figures, a variable sized electrode receiver is provided to retain electrode  204  within the torch head in a position axially extending through manifold  114  and centrally located within an inert gas atmosphere. As illustrated, one embodiment of electrode receiver  201  comprises a plurality of electrode securing wedges  206  positioned radially within a guide housing  208 . The wedges form an aperture therebetween, where the aperture size is adjustable based upon the position of the wedges relative to an internal conical surface  217  within the housing  208 . Each securing wedge traverses the conical surface in a longitudinal direction to form the variable aperture. In use an electrode  204  passes through said variable aperture in contact with each securing wedge, said securing wedges further providing electrical contact between the electrode and the conical surface, and thus the source of electrical current. An adjusting collar positions the securing wedges longitudinally along the internal conical surface, where the adjusting collar forces the wedges into secure contact with the electrode, and the aperture is adjustable for use with a range of electrode diameters. The torch head may further include a manifold  114  for gas containment, seat  222  working in relationship with wedge guide housing  208  having wedges  206  retained therein. Springs  218  serve to provide a tendency force against wedge  206  so as to encourage a constant contact with wedge guide  208  in the absence of electrode  204 . Conducted heat from the arc through electrode receiver  201  is dissipated into the liquid circulating collar  228 , whereby the heat energy is further transferred to cooler  106  via liquid lines and expelled as warm air. Back cap  202  threads into tail piece  216  to prevent any inert gas from escaping through the distal end of electrode receiver  201 . 
     As discussed previously, the aperture sizing is dependent upon the geometric relationship of the conical surface  217  and electrode securing wedges  206 , and may be used to produce an aperture of diameter D to handle electrode diameters from about 0.020 in. to about 0.250 in, and more preferably from about 0.040 in. to about 0.125 in. As will be appreciated the apertures may be adjustable to diameters slightly smaller than the smallest electrode diameter noted and slightly larger than the largest diameter of the electrode in order to accommodate imperfections in, and contamination of, the electrodes. 
     Use of the disclosed embodiments is believed to result in improved productivity by at least eliminating the need to change collets when switching between various electrode diameters or shapes. For example, one method for using the disclosed welding torch in combination with an arc welder, includes providing an adjustable electrode receiver having a plurality of electrically conductive wedges defining an aperture, where the aperture is suitable for receiving a plurality of electrodes of different diameters. To use the torch, an electrode is inserted into the aperture in the electrode receiver, the wedges are adjusted to be in electrical contact with the outer surface of the electrode, and the electrode is secured in a fixed position by applying a force to the wedges via a threaded collar or similar mechanism in contact with the electrode. Another electrode may then be used by readjusting the position of the threaded collar in contact with the electrode securing wedges to release the first electrode, and removing the first electrode from the electrode aperture before inserting a second electrode of a different diameter into the electrode aperture. Once inserted the securing wedges are adjusted to be in electrical contact with an outer surface of the second electrode; and once again used to secure the second electrode in a fixed position by applying a force to the securing wedges via the threaded collar in contact with the wedges. 
     It will be appreciated that several of the above-disclosed embodiments and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also, various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the description above and the following claims.