Patent Description:
GTAW or TIG welding is an arc welding process that passes an electric current through a non-consumable tungsten electrode to generate an arc between the electrode and a workpiece. The electrode is made from tungsten or tungsten alloy because of its high melting temperature, e.g., about <NUM>,<NUM> (<NUM>,<NUM> °F), which helps prevent consumption of the electrode. A filler metal may be introduced to the arc between the electrode and the workpiece, or two workpieces may be joined by melting the workpieces, via the arc, along a joint. A weld pool is created at the workpiece from the workpiece material and/or a filler metal melted by the arc. If atmospheric gases (e.g., nitrogen, oxygen, carbon dioxide, etc.) come into contact with the electrode, the arc, and/or weld pool during the welding process, this can cause fusion defects, porosity, and/or weld metal embrittlement. Accordingly, protecting the electrode, arc, and weld pool from atmospheric gases is desirable. Typically, the electrode, arc, and weld pool are protected from atmospheric gases by an inert shield gas, e.g., argon and/or helium. However, even with the inert shield gas, some contamination may occur, negatively impacting the weld and/or causing electrode to wear and/or oxidize. TIG/GTAW welding operations generate heat in the electrode based on the arc length of a generated arc, e.g., the distance between the electrode and the workpiece. For example, the greater the arc length, the more heat generated in the electrode. Additional heat may be generated by the transmission of the current from an electrode holder, typically made of copper, to the tungsten electrode. For example, the electrode holder may be mechanically coupled to the tungsten electrode forming interstitial spaces between the holder and electrode. The interstitial spaces decrease the contact area between the holder and the electrode in which the current may pass. Thus, the current may flow around the interstitial spaces and may be funneled to the contact areas where it is transmitted to the electrode. The localized flow of current at the contact areas causes resistive heating of the electrode and holder. The width of the arc increases in response to an increase in the temperature of the electrode. That is, the hotter the electrode, the wider the arc from the electrode to the workpiece, impacting the size of the weld pool and quality of the weld. Further, if the electrode temperature is too high, the electrode may be damaged by splatter from the weld pool and/or inadvertent contact with the workpiece.

Although higher electrode temperatures may increase a depth of the weld pool, higher electrode temperatures also increase the weld pool surface area in TIG welding processes, negatively impacting at least weld precision and weld strength. In some instances, the power supplied to the electrode may be controlled to adjust the temperature of the electrode. However, adjusting the power generally does not increase the depth of the weld pool or weld penetration as much as it increases the surface area of the weld pool. Thus, such adjustments may not control temperature while achieving a strong and precise weld (e.g., a relatively narrow weld with sufficient penetration). Alternatively, weld penetration may be improved by adding an active gas to the weld area (e.g., carbon dioxide, oxygen). However, active gases generally cause conventional tungsten electrodes to wear prematurely, requiring frequent maintenance and/or replacement of the electrode.

Conventional tungsten electrodes and electrode holders typically have a long length to help dissipate and control the heat from the electrode generated by the welding process. For example, a length of conventional tungsten electrodes can range from about <NUM> to <NUM> (<NUM> to <NUM> in). However, the length of the electrode impacts the size of the torch, and prevents the torch from being used on workpieces having a cramped weld area.

In view of at least the aforementioned issues, an improved GTAW/TIG torch and electrode that improves heat dissipation and weld penetration is desirable. German Patent Application Publication No. <CIT> (describing the preamble of claims <NUM>, <NUM> and <NUM>) discloses a burner with an electrode penetrating a holder in a body. The holder has a conical region interacting with a conical region of the body via threads. The holder also includes clamping segments. German Patent Application Publication No. <CIT> discloses a burner that includes a housing, an electrode unit held by an electrode holder and surrounded by a nozzle, and a cooling device within the housing. The electrode unit includes an electrode fixed in a shaft, and the electrode unit is held in the electrode holder by a press fit and/or a material fit. International Patent Application Publication No. <CIT> discloses a torch body, an electrode inserted into the torch body and connected to a cathode, a narrow nozzle that supports a tip of the electrode to form a gas passage between the electrode and the narrow nozzle, and an electrode nozzle outside of the narrow nozzle to form gas vent openings. European Patent Application No. <CIT> discloses a torch with a torch head having a housing cylinder with an upper cover clasp for coolant flow, a body in the housing cylinder, a cavity that opens at a side of the body, an interior cover clasp on the body, and a countersunk tapped hole on another side of the body. The interior cover clasp defines a flow line for coolant. An electrode is inserted into the countersunk tapped hole. The electrode has a cylindrical tungsten electrode body and an electrode holder in which the electrode body is secured. The opening angle of the tip of the electrode is <NUM>-<NUM> degrees.

The present invention relates to a torch and electrode for a TIG/GTAW welding operation. In a first aspect of the present invention, there is provided an assembly in accordance with claim <NUM>.

In a second aspect of the present invention, a system with such assembly is defined in claim <NUM>, and according to a third aspect of the present invention, a method is defined in claim <NUM>.

To complete the description and in order to provide for a better understanding of the present invention, a set of drawings is provided. The drawings form an integral part of the description and illustrate an embodiment of the present invention, which should not be interpreted as restricting the scope of the invention, but just as an example of how the invention can be carried out.

The following description is not to be taken in a limiting sense but is given solely for the purpose of describing the broad principles of the invention. Embodiments of the invention will be described by way of example, with reference to the above-mentioned drawings showing elements and results according to the present invention.

Generally, a TIG/GTAW torch with improved electrode temperature control (or heat dissipation) and weld penetration, as compared to conventional TIG/GTAW torches, is disclosed. The torch includes a tungsten, or tungsten alloy, electrode integrated with a copper holder. The torch further includes an inert gas flow path along the electrode, and an active gas flow path outside of and concentric with the inert gas flow path. The inert gas flow path along the electrode is set at a steep angle with respect to a longitudinal axis of the electrode. For example, the steep angle may be about <NUM> to <NUM> degrees from the longitudinal axis, such as approximately <NUM> degrees. During operation, the active gas decreases the surface tension of the weld pool which causes the weld pool to flow downward into the workpiece. Therefore, the weld penetration, e.g., how deep the weld pool penetrates the workpiece, increases at lower temperatures as compared to conventional TIG/GTAW welding operations.

The flow of inert gas along the electrode prevents the active gas, and/or atmospheric gases, from contacting the electrode and arc during welding. That is, the flow of inert gas acts as a curtain, preventing the flow of the active and/or atmospheric gases from reaching the arc and electrode. Thus, premature wear and/or oxidation of the electrode is prevented. The flow of inert gas is a high-speed laminar flow directed along the electrode at the steep angle. The high-speed laminar flow is generated by a back pressure generated in a plenum fluidly coupled to an inert gas channel in the torch body. The high-speed laminar flow and the steep angle generate the protective curtain of inert gas around the electrode.

The TIG/GTAW torch may be connected to a controller which controls the flow of inert gas, flow of active gas, a flow of cooling fluid, and a weld power (e.g., voltage and/or current) supplied to the torch during a welding operation. The controller may adjust the flow of inert and active gases, flow of cooling fluid, and weld power based on sensed weld parameters, e.g., weld current, weld voltage, weld penetration, etc..

Now referring to <FIG>, an exemplary embodiment of a torch <NUM> for performing gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding is shown. The torch <NUM> includes a torch body <NUM> and torch head <NUM>. The torch body <NUM> is configured to connect to a power supply line <NUM>, a cooling fluid supply line <NUM>, and cooling fluid return line <NUM>, a first shield gas supply line <NUM>, and a second shield gas supply line <NUM>. The torch head <NUM> includes a shield cap <NUM>, nozzle <NUM>, and rectifier <NUM> disposed between the shield cap <NUM> and nozzle <NUM>.

The torch body <NUM> and torch head <NUM> receive an electrode assembly <NUM> having an electrode <NUM> integrated with an electrode holder <NUM> (see <FIG>), as is discussed further below with reference to <FIG>. The torch body <NUM> is configured to transmit current from the power supply line <NUM> and cooling fluid from the cooling fluid supply line <NUM> to the electrode assembly <NUM> during a welding operation. The torch body <NUM> is further configured to supply the first and second shield gases from the first and second shield gas supply lines <NUM>, <NUM> to the torch head <NUM>.

Now referring to <FIG>, a rear view of the torch body <NUM> with cross sections taken along lines A-A, B-B, C-C, and D-D are shown. The torch body <NUM> includes ports <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> for receiving the power supply line <NUM>, the cooling fluid supply line <NUM>, the cooling fluid return line <NUM>, the first shield gas supply line <NUM> and the second shield gas supply line <NUM>, respectively. <FIG> is a cross section of the torch body <NUM> taken along line A-A of <FIG>. The torch body <NUM> includes a cavity <NUM> for receiving the electrode assembly <NUM> and a portion of the nozzle <NUM>. As shown, the cavity <NUM> extends through a length of the torch body <NUM> along axis <NUM>. The cavity <NUM> includes six cavity portions <NUM>-<NUM> configured to receive the electrode assembly <NUM> and/or a portion of the nozzle <NUM>. Each cavity portion <NUM>-<NUM> may have a diameter that is different than an adjacent portion. For example, cavity portion <NUM> may have the largest diameter, and may be configured to allow the electrode assembly <NUM> to be inserted into or removed from the torch body <NUM>. An electrode plug <NUM> or cover, may be received in cavity portion <NUM>. While the cavity <NUM> is shown as having six portions, embodiments are not limited thereto. The cavity <NUM> may be configured with any number of cavity portions for receiving the electrode assembly. For example, the cavity <NUM> may have more than six cavity portions, or less than six cavity portions.

Cavity portion <NUM> includes a first bearing surface 172A and a second bearing surface 172B, and may be configured act a seat to support the electrode assembly <NUM>. For example, first bearing surface 172A may provide an axial support for the electrode assembly <NUM> in a direction parallel to axis <NUM>. The second baring surface172B may provide radial support to the electrode perpendicular to axis <NUM>.

Cavity portion <NUM> is configured to act as a cooling chamber for the electrode assembly <NUM>. For example, a cooling fluid may flow through the cooling chamber <NUM> to remove heat generated during the welding process. Cooling fluid supply channel <NUM> fluidly couples the cavity portion <NUM> with the cooling fluid supply port <NUM> (see <FIG>). Cooling fluid return channel <NUM> fluidly couples cavity portion <NUM> with the cooling fluid return port <NUM> (see <FIG>). A portion of the inner surface 173A of cavity portion <NUM> may provide radial support to the electrode assembly <NUM>, perpendicular to axis <NUM>.

Cavity portion <NUM> may be configured to act as a second seat to support the electrode assembly <NUM>. For example, second bearing surface 174A may provide axial support to the electrode assembly <NUM> parallel to axis <NUM>. Sidewall 174B of cavity portion <NUM> may provide radial support to the electrode assembly <NUM> perpendicular to axis <NUM>. For example, sidewall 174B may contact an outer surface of the electrode assembly <NUM> to prevent radial movement of the electrode assembly <NUM> within the torch body <NUM>.

Cavity portion <NUM> may be configured to receive a portion of the electrode assembly <NUM>. Sidewall 175A defining cavity portion <NUM> may provide radial support of the electrode assembly <NUM>, perpendicular to axis <NUM>. For example, sidewall 175A may contact an outer surface of the electrode assembly <NUM> to prevent radial movement of the electrode assembly <NUM> within the torch body <NUM>.

Cavity portion <NUM> may be configured to receive the nozzle <NUM>. For example, an inner wall 176A defining cavity portion <NUM> may be threaded to receive corresponding threads 148of the nozzle <NUM> (see <FIG>). Additionally or alternatively, the nozzle <NUM> may be attached to the inner wall 176A via friction fit, snap fit, and/or a cam latch.

As is shown in <FIG>, a first shield gas channel <NUM> is fluidly couples cavity portion <NUM> with first shield gas port <NUM>. In the depicted embodiment, the channel <NUM> includes a first channel portion 114A and a second channel portion 114B substantially perpendicular to the first channel portion 114A. Specifically, the first channel portion 114A extends perpendicular to the axis <NUM> and the second channel portion 114B extends in a direction parallel to the axis <NUM>. However, in other embodiments, first shield gas channel <NUM> may include any number of portions that extend in any direction(s).

<FIG> shows the second shield gas channel <NUM>. The second shield gas channel <NUM> supplies the flow of second shield gas from the second shield gas port <NUM> to the shield cap <NUM>. The second shield gas channel <NUM> includes a horizontal channel 115A extending substantially horizontally, or perpendicular to axis <NUM>, from the second shield gas port <NUM> to a distal end 115B. A transverse channel 115C intersects the horizontal channel 115A extending at an angle γ from the horizontal. That is, the transverse channel 115C extends from the distal end 115B downward and towards an outer periphery of the torch body <NUM>, creating an acute bend in the second shield gas channel <NUM>. For example, the second shield gas channel <NUM> may have a "V" shape, with an angle γ of about <NUM> to <NUM> degrees. In some implementations, the angle γ may be about <NUM> degrees. When a flow of shield gas travels through the second shield gas channel <NUM>, back pressure may be created in the flow of shield gas based, in part, on the configuration of the second shield channel <NUM>. That is, the acute bend in the channel <NUM> assists in creating a back pressure in the flow of second shield gas. The back pressure in the flow of the second shield gas assists in creating and maintaining a laminar flow of the second shield gas through the shield cap.

Referring to <FIG>, the electrode assembly <NUM> is shown. The electrode assembly <NUM> includes an electrode <NUM> having a substantially cylindrical shape and electrode holder <NUM>. The electrode <NUM> includes a distal end <NUM>. In the depicted embodiment, the distal end <NUM> has a substantially conical shape. An angle θ1 of the cone is about <NUM> degrees. That is, an angle θ1 between two opposite outer surfaces 212A, 212B of the distal end <NUM> of the electrode <NUM> is about <NUM> degrees, +/- <NUM> degrees. In other words, an angle between a longitudinal axis <NUM> of the electrode assembly <NUM> and an outer surface 212A, 212B of the distal end <NUM> is about <NUM> degrees, +/- <NUM> degree. However, in other embodiments, the distal end <NUM> may have a frustoconical shape or a conical shape of different dimensions, such as a frustoconical shape with an angle θ1 between two opposite outer surfaces in the range of about <NUM>-<NUM> degrees.

The electrode holder <NUM> includes a proximal or contact portion <NUM>, a central or cooling portion <NUM> and a distal or holding portion <NUM>. The contact portion <NUM> has a cylindrical shape defined by an outer surface 224A, and is configured to receive a weld current from the power supply line <NUM>. The contact portion <NUM> further includes a first bearing member <NUM> having a bearing surface 226A configured to rest on the bearing surface 172A of cavity portion <NUM> of the torch body <NUM> (see <FIG>). The outer surface 224A may be configured to contact the inner surface 172B of cavity portion <NUM> (see <FIG>).

The central or cooling portion <NUM> is generally cylindrically shaped and is configured to dissipate heat from the electrode holder <NUM> during a welding process. The cooling portion <NUM> includes a plurality of fins, protrusions, or ribs, <NUM> extending radially. The plurality of fins <NUM> are separated by a plurality of gaps <NUM>. The cooling portion <NUM> further includes a second bearing member <NUM> having a radial bearing surface 236A and a third bearing member <NUM> having an axial bearing surface 238A and radial bearing surface 238B. The radial bearing surface 236A is configured to contact the inner surface 173A of cavity portion <NUM> of the torch body <NUM> (see <FIG>). The axial bearing surface 238A is configured to rest on the bearing surface 174A of the torch body <NUM> (see <FIG>). The radial bearing surface 238B is configured to contact the sidewall 174B of cavity portion <NUM>.

The holding portion <NUM> includes a cylindrical portion <NUM> and a frustoconical portion <NUM>. The holding portion <NUM> includes bond interface <NUM> between to the electrode <NUM> and electrode holder <NUM>. An outer surface 242A of the cylindrical portion <NUM> may be configured to contact the sidewall 175A of cavity portion <NUM> (see <FIG>) to prevent radial movement of the electrode assembly <NUM> when received in the torch body <NUM>. Meanwhile, an outer surface of the frustoconical portion <NUM> is configured to cooperate with the nozzle <NUM> to guide a laminar flow of the first shield gas to the electrode <NUM>, as is described in further detail below.

An inner surface of the frustoconical portion <NUM> is configured to align with the outer surface of the distal end <NUM> of the electrode <NUM>. That is, an angle θ2 between two opposite outer surfaces of the frustoconical portion <NUM> of the electrode holder <NUM> is substantially equal to angle θ1 of the distal end <NUM> of the electrode <NUM>. Thus, in the embodiment shown, angle θ2 is about <NUM> degrees, +/- <NUM> degrees. In other words, an angle between a longitudinal axis <NUM> of the electrode assembly <NUM> and an outer surface of the frustoconical portion <NUM> is about <NUM> degrees, +/- <NUM> degree. However, again, in other embodiments, the distal end <NUM> may have a frustoconical shape of different dimensions, such as a frustoconical shape with an angle θ2 between two opposite outer surfaces in the range of about <NUM>-<NUM> degrees.

The electrode <NUM> material is tungsten. The electrode holder <NUM> is copper. The electrode holder <NUM> may be back-casted directly to the tungsten electrode <NUM>. For example, the tungsten electrode <NUM> may be disposed in a mold, or crucible, and molten copper may be added to the mold. The molten copper slowly cools from around the tungsten electrode <NUM> to the contact portion <NUM>, such that a crystalline structure of the cooling copper aligns with a crystalline structure of the tungsten electrode. The interface <NUM> between the tungsten of the electrode <NUM> and copper of the electrode holder <NUM> may be a metallic bond or Van der Waals bond. At interface <NUM> between the electrode <NUM> and electrode holder <NUM>, copper atoms from the electrode holder <NUM> may be diffused into the tungsten of the electrode <NUM>. According to the present invention, the electrode holder <NUM> is molecularly bonded to the electrode <NUM> (e.g., atoms and/or electrons of the electrode holder <NUM> interact with atoms and/or electrons of the electrode <NUM> to form the bond). Thus, the electrode <NUM> and electrode holder <NUM> are integrated into a single electrode assembly <NUM>.

The integrated electrode assembly <NUM> has no boundary layers that impede heat transfer between the electrode <NUM> and the cooling portion <NUM> of the electrode holder <NUM>. For example, because the electrode <NUM> and electrode holder <NUM> are bonded at the molecular level during a weld process, heat can easily be transmitted through the electrode <NUM> across interface <NUM> to the cooling portion <NUM> of the electrode holder <NUM>. Thus, the integrated electrode assembly <NUM> may have improved heat dissipation as compared to conventional TIG/GTAW electrodes mechanically coupled to electrode holder assemblies. Additionally, the lack of interstitial spaces between the electrode holder contact portion <NUM> and the electrode <NUM> reduces the generation of resistive heating in the assembly as compared to conventional tungsten electrodes mechanically coupled to electrode holders. The improved heat dissipation and/or the reduced heat generation allow the electrode <NUM> to have one-half to one-fifth the length of conventional tungsten electrodes. For example, the tungsten electrode <NUM> may have a length of <NUM> to <NUM> (<NUM> to <NUM> in).

Referring to <FIG>, a nozzle <NUM> is shown. The nozzle <NUM> includes a nozzle cavity <NUM>, an upper surface <NUM>, and an inner surface <NUM> defining the nozzle cavity <NUM>. The nozzle cavity <NUM> is configured to receive and substantially mirror an outer surface of the electrode assembly <NUM>. That is, the nozzle cavity <NUM> is formed by opposing inner surface <NUM> that form an angle θ3 therebetween. The angle θ3 may be about <NUM> degrees +- <NUM> degrees so that it mirrors the angles θ1 and θ2 of the outer surfaces of the electrode <NUM> and electrode holder <NUM>, respectively, and facilitates the formation of the high-speed, laminar flow <NUM> and constraint of the arc <NUM> noted above. Alternatively, the angle θ3 may have any dimension that mirrors (e.g., matches) the angles of the electrode <NUM> and electrode holder to form a passageway of a constant diameter. However, in still other embodiments, the angle θ3 may be dimensioned to form a passageway that converges or diverges towards the distal end of the electrode assembly, provided that the divergence or convergence facilitates the formation of the high-speed, laminar flow <NUM> and constraint of the arc <NUM> noted above.

The nozzle <NUM> further includes circumferential protrusion <NUM> radially extending from an outer surface <NUM>. A circumferential groove <NUM>, extending radially inward, is disposed adjacent to, but above, the circumferential protrusion <NUM>. The circumferential protrusion <NUM> and groove <NUM> are configured to support an inner diameter of a rectifier <NUM> (see <FIG>). The nozzle <NUM> further includes a threaded portion <NUM> for engaging corresponding threads at cavity portion <NUM> of the torch body <NUM>.

To withstand the heat generated during the welding operation, the nozzle <NUM> may comprise a sintered copper-tungsten alloy. For example, the nozzle <NUM> may contain about <NUM> percent tungsten and about <NUM> percent copper. The sintering operation may comprise mixing a tungsten powder with a copper powder and providing the mixed powder into a mold. The mold is heated to melt the copper, and then cooled. Thus, a sintered copper-tungsten nozzle is formed with the tungsten and copper molecularly bonded together. The sintered copper-tungsten nozzle <NUM> can resist and dissipate received heat during the welding operation.

Referring to <FIG>, a shield cap <NUM> is shown. The shield cap <NUM> includes cap cavity <NUM>, a mounting portion <NUM> and a fluid guide portion <NUM>. The cap cavity <NUM> is defined by an inner surface <NUM>, a threaded surface <NUM> of the mounting portion <NUM>, and an inner surface <NUM> of the fluid guide portion <NUM>. The threaded surface <NUM> is configured to engage threads of the lower portion <NUM> of the torch body <NUM>. For example, the shield cap <NUM> may be threaded onto the lower portion <NUM> of the torch body <NUM>. The inner surface <NUM> of the fluid guide portion <NUM> is configured to guide the laminar flow <NUM> of the second shield gas <NUM>. For example, the inner surface <NUM> may be angled. That is, an angle φ between opposing inner surfaces <NUM> may be selected to guide the laminar flow <NUM> of the second shield gas <NUM> to the work piece. For example, the angle may be <NUM> degrees +- <NUM> degrees so that it mirrors a slope of the outer surface <NUM> of the nozzle <NUM> and facilitates the formation of laminar flow <NUM> of the second shield gas <NUM>. Altematively, the angle φ may have any dimension that mirrors (e.g., matches) the angles of the outer surface <NUM> of the nozzle <NUM> to form a passageway of a constant diameter. However, in still other embodiments, the angle θ3 may be dimensioned to form a passageway that converges or diverges towards the distal end of the electrode assembly, provided that the divergence or convergence that facilitates the formation of laminar flow <NUM> of the second shield gas <NUM>.

The shield cap <NUM> further includes a rectifier seat <NUM> for supporting the rectifier <NUM>. The rectifier seat <NUM> is disposed between the threaded surface <NUM> and the inner surface <NUM> of the fluid guide portion <NUM>. The rectifier seat <NUM> extends radially into the cap cavity <NUM>.

When the shield cap <NUM> is attached to the lower portion <NUM> of the torch body <NUM>, the inner surface <NUM> cooperates with the lower portion <NUM> to form a plenum <NUM> (see <FIG> and <FIG>). Additionally, the rectifier seat <NUM> and nozzle <NUM> cooperate to retain the rectifier <NUM>. For example, an outer circumference of the rectifier <NUM> rests on the rectifier seat <NUM> of the shield cap <NUM> and an inner circumference of the rectifier <NUM> engages the protrusion <NUM> and groove <NUM> of the nozzle <NUM>. In some embodiments, installing the shield cap <NUM> on the lower portion <NUM> of the torch body <NUM> may also secure the electrode assembly <NUM> and/or nozzle <NUM> to the torch body <NUM> (e.g., if the nozzle <NUM> does not include threads and/or the electrode assembly <NUM> does not include bearing surfaces and other such assembly features).

Referring to <FIG>, an annular rectifier <NUM> is shown having an inner circumference 151A and an outer circumference 151B. In this embodiment, the rectifier <NUM> comprises a first annular disc <NUM> stacked on a second annular disc <NUM>.

The first annular disc <NUM> includes a first set through-holes 154A radially disposed about the inner circumference. A second set of through-holes 154B are disposed concentrically with the first set of through-holes 154A. For example, the first set of through-holes 154A are disposed at a first radius (measured from a center of the first annular disc <NUM>) and the second set of through-holes 154B are disposed at a second radius (measured from a center of the first annular disc <NUM>) greater than the first radius. The first and second set of through-holes 154A, 154B are disposed at a radially inner half to inner two-thirds of the first annular disc <NUM>. Diameters of the second set of through-holes 154B are larger than diameters the first set through-holes 154A. In the depicted embodiment, each of the first set and second set of through-holes 154A, 154B are shown as having <NUM> holes, for a total of <NUM> through-holes. However, embodiments are not limited thereto.

The second annular disc <NUM> includes a plurality of oblong through-holes <NUM>. The through-holes <NUM> include an outer sidewall 155A and a radially inner sidewall 155B. The outer and inner sidewalls 155A and 155B are curved. The radius of the curve of sidewall 155A is larger than a radius of a curve of sidewall 155B.

During operation, the second shield gas <NUM> flows through the through-holes 154A, 154B, <NUM> and into the shield cap cavity <NUM>. Any circumferential velocity of the flow of second shield gas <NUM> is converted into axial flow through the through-holes 154A, 154B, <NUM>. Thus, the through-holes 154A, 154B, <NUM> throttle the flow of the second shield gas <NUM>. In some implementations, the first and second annular discs <NUM>, <NUM> and through-holes 154A, 154B, <NUM> may be stamped from sheet metal. The first and second discs <NUM>, <NUM> may have any number and configuration of through-holes to create a back pressure in the flow of first shield gas <NUM> and the laminar flow <NUM> exiting the rectifier <NUM>.

Referring to <FIG> and <FIG>, the torch <NUM> and electrode assembly <NUM> are now shown with fluid flowing therethrough during a weld operation. During the welding operation, a weld current, cooling fluid <NUM>, a first shield gas <NUM>, and a second shield gas <NUM> are supplied to the torch <NUM> via supply lines <NUM>-<NUM>. The current supplied to the torch <NUM> is transmitted to the electrode assembly <NUM> to create an arc <NUM> at the electrode distal end <NUM>. The arc may be used to melt a work piece and/or filler material during welding. The current and arc <NUM> generate heat in the electrode assembly <NUM>.

Cooling fluid <NUM> is supplied to the torch body <NUM> via cooling fluid supply line <NUM> to dissipate the heat generated in the electrode assembly <NUM> during a welding operation. The cooling fluid <NUM> flows through the cooling fluid supply port <NUM> to the cooling chamber <NUM> via cooling fluid supply channel <NUM> (shown in <FIG>). The cooling fluid <NUM> flows through the gaps <NUM> between the fins <NUM> of the electrode assembly <NUM>. For example, the cooling fluid <NUM> may spiral around the cooling or central portion <NUM> of the electrode assembly <NUM>. Heat generated during the welding operation is conducted, or transmitted, to the cooling fluid <NUM>. Because the electrode <NUM> is molecularly bonded to the electrode holder <NUM>, there are substantially no boundary layers to impede the flow of heat between the electrode <NUM> and the cooling portion <NUM> of the electrode holder <NUM>. Accordingly, the cooling portion <NUM> can efficiently dissipate the heat from the electrode <NUM> to the cooling fluid <NUM>. The cooling fluid <NUM>, and the heat transferred to it, flows out of the cooling chamber <NUM> through cooling fluid return channel <NUM> and out of the torch body <NUM> through the cooling fluid return port <NUM> to cooling fluid return line <NUM>. Accordingly, the heat generated during the weld operation is dissipated, transferred to the cooling fluid, and removed from the system via the cooling fluid return line <NUM>. Thus, the electrode assembly <NUM> is efficiently cooled and the temperature of the distal end <NUM> of the electrode <NUM> may be maintained at a desired temperature, e.g., at, or below, about <NUM> degrees Celsius, preferably about <NUM> degrees Celsius.

Seals <NUM> are disposed between the electrode assembly <NUM> and the torch body <NUM>. The seals prevent cooling fluid from leaking from cavity portion <NUM>. For example, a seal <NUM> (e.g., an O-ring) may be disposed between the contact portion <NUM> of the electrode holder <NUM> and the bearing surface 172A of cavity portion <NUM> of the torch body <NUM>. Another seal <NUM> (e.g., an O-ring) may be disposed between the third bearing member <NUM> of the electrode holder <NUM> and the bearing surface 174A of the torch body <NUM>.

In some implementations, the cooling fluid <NUM> may be a gas or a liquid. For example, the cooling fluid may be air or water, however, embodiments are not limited thereto. The cooling fluid may be any fluid capable of removing a desired amount of heat from the cooling portion <NUM>. Due to the efficient cooling of the electrode assembly <NUM>, the overall length of the electrode <NUM> and electrode holder <NUM> may be shorter than conventional TIG/GTAW electrodes and holders. Additionally, the flow of cooling fluid may be supplied by conventional TIG/GTAW water pumps without the use of a chiller. That is, due the properties efficient cooling of the electrode assembly <NUM>, unchilled liquid may be used as a cooling fluid <NUM>.

Still referring to <FIG> and <FIG>, the first shield gas <NUM> flows into the torch body <NUM> from supply line <NUM> via port <NUM>. Channel <NUM> guides a flow of first shield gas <NUM> from port <NUM> to a first plenum <NUM> disposed at the end of channel <NUM>. The first plenum <NUM> comprises an annular cavity formed between the torch body <NUM> and an upper surface <NUM> of the nozzle <NUM>. The first plenum <NUM> and channel <NUM> may create back pressure in the flow of first shield gas <NUM>. From the first plenum <NUM>, the first shield gas <NUM> flows between the electrode assembly <NUM> and inner surface <NUM> of the nozzle <NUM>, enveloping the holding portion <NUM> and the electrode <NUM> of the electrode assembly <NUM> in a high-speed, laminar flow <NUM> of first shield gas <NUM>. That is, high-speed, the laminar flow <NUM> of first shield gas <NUM> completely surrounds the holding portion <NUM> and the electrode <NUM> of the electrode assembly <NUM>, preventing other gases from contacting the electrode <NUM>. Put yet another way, the outer surface of the electrode assembly and the inner surface <NUM> of the nozzle form a radial gap and the first shield gas <NUM> flows from channel <NUM> into the radial gap to surround the electrode assembly <NUM> (the plenum <NUM> may also be an annular plenum formed in the radial gap).

The flow <NUM> is a high-speed, laminar flow because of the back pressure in the plenum <NUM>, the close proximity of the electrode assembly <NUM> to the inner surface <NUM> of the nozzle <NUM>, angle θ3 of opposing inner surfaces <NUM> of the nozzle <NUM> (see <FIG>), and/or the angles θ1, θ2, of the opposing outer surfaces of the holding portion <NUM> and the electrode <NUM> (see <FIG>). For example, a radial gap between an outer surface of the electrode assembly <NUM> and the inner surface <NUM> of the nozzle <NUM> may be about <NUM> to <NUM> (<NUM>. 01in to <NUM>. In some implementations, the angles θ1, θ2, θ3, may be about <NUM> degrees +-<NUM> degrees which may provide a steep chamber that encourage high-speed flow which assists in constraining the arc <NUM>. The high-speed, laminar flow <NUM> of the first shield gas <NUM> provides a stable, radially constrained arc <NUM>. That is, due to the high-speed, laminar flow <NUM> discharged at a steep angle by the nozzle <NUM>, the arc <NUM> is focused at a desired distance from the distal end <NUM> of the electrode <NUM>. For example, the sharp angles θ1, θ2, θ3 of the electrode assembly <NUM> and the nozzle <NUM> facilitate a high-speed, laminar flow <NUM> of the first shield gas <NUM> that constrains and focuses the arc <NUM> at the desired distance during a welding operation. The desired distance may be the desired arc length between the distal end <NUM> of the electrode and a work piece. Additionally, the high-speed, laminar flow <NUM> provides a gas-curtain, preventing other gases from contacting the electrode <NUM> and/or the arc <NUM>.

Because the arc <NUM> is radially constrained by the high-speed, laminar flow <NUM>, the desired arc length may be varied by a larger amount than conventional TIG/GTAW welding. For example, the desired arc length may range from <NUM> to <NUM> (<NUM>. 02in to <NUM>. In some implementations, an arc length of <NUM> (<NUM>. 059in) is desirable. Accordingly, the arc <NUM> is less susceptible to fluctuations that can impact weld quality in response to changes in weld parameters, e.g., arc length, current, voltage, temperature, shield gas pressure, etc..

The first shield gas <NUM> may be an inert gas, or mixture of gases, e.g., argon, helium, nitrogen, oxygen, carbon dioxide, nitrogen dioxide, hydrogen, etc. The flow rate of the first shield gas <NUM> may be any desired flow rate to create a high-speed, laminar flow <NUM>, e.g., without turbulence, between the inner surface <NUM> of the nozzle <NUM> and an outer surface of the electrode assembly <NUM>. For example, the flow rate of the first shield gas <NUM> may be <NUM> to <NUM> liters per minute ("l/min") (<NUM> - <NUM> cubic feet per minute ("cfm")). In some implementations the flow rate may be <NUM>/min (<NUM> cfm).

Still referring to <FIG> and <FIG>, the second shield gas <NUM> flows through the torch body <NUM> via channel portions 115A and 115B of the second shield gas channel <NUM> to a plenum <NUM>. The plenum <NUM> is a cavity formed between the lower portion <NUM> of torch body <NUM> and an inner surface <NUM> of the shield cap <NUM>. From the plenum <NUM>, the second shield gas <NUM> flows through channels 115C radially disposed about the lower portion <NUM> of the torch body <NUM> to a rectifier <NUM>. Channels 115C extend substantially parallel to axis <NUM>. The rectifier is disposed between the shield cap <NUM> and nozzle <NUM>. The rectifier <NUM> is configured to receive the flow of the second shield gas <NUM> from channels 115C and to diffuse and rectify a direction of the flow through the shield cap <NUM>. For example, the flow of the second shield gas <NUM> may include circumferential flow when it exits channels 115C that is diffused and rectified by the rectifier <NUM> to flow through the shield cap <NUM>.

The rectifier <NUM>, plenum <NUM>, and channels <NUM>, 115C contribute to generating back pressure in the flow of the second shield gas <NUM>, such that a laminar flow <NUM> of the second shield gas <NUM> is generated and maintained through cap cavity <NUM> of the shield cap <NUM>. The laminar flow <NUM> of the second shield gas <NUM> passes through the shield cap <NUM>. Put another way, the outer surface of the nozzle <NUM> and the inner surface of the shield cap <NUM> form a radial gap and the second shield gas <NUM> flows from channel <NUM> into the radial gap to surround the nozzle <NUM> (In some implementations, the plenum <NUM> and rectifier <NUM> may also be annular and formed in the radial gap). During a welding operation, the laminar flow <NUM> of the second shield gas contacts a workpiece. The electrode <NUM> is protected from the laminar flow <NUM> of the second shield gas <NUM> by the high-speed, laminar flow <NUM> of the first shield gas <NUM>. That is, the high-speed, laminar flow <NUM> of the first shield gas <NUM> prevents the second shield gas <NUM> from contacting the electrode <NUM>.

The second shield gas <NUM> may be an inert gas or mixture of inert gases. For example, the second shield gas may include argon and/or helium. In some implementations, the second shield gas <NUM> may further include one or more active gases. For example, active gases such as oxygen, nitrogen, hydrogen, and/or carbon dioxide may be added to the inert gas. For example, the second shield gas may be a gas mixture comprising about <NUM> to <NUM>% nitrogen, about <NUM> to <NUM>% carbon dioxide, about <NUM> to <NUM>% oxygen, about <NUM> to <NUM>% hydrogen, and the remainder comprising argon and/or helium when used with stainless steel or other alloys of steel. In some implementations, the gas mixture may be about <NUM>% argon, about <NUM>% nitrogen, about <NUM>% hydrogen, and about <NUM>% carbon dioxide. The addition of active gases to the second shield gas <NUM> may impact the quality of weld. For example, adding carbon dioxide improves weld penetration, e.g., how deep the weld pool travels into the work piece, by reducing the surface tension of the weld pool and reversing the Marangoni flow within the weld pool. As a further example, adding nitrogen to the second shield gas <NUM> may control the content of ferritic and/or austenitic stainless steel in a weld. Accordingly, thicker workpieces may be welded with improved weld quality and less heat as compared to conventional TIG/GTAW torches.

The flow rate of the second shield gas <NUM> may be any desired flow rate to create the laminar flow <NUM>, e.g., without turbulence, between an outer surface <NUM> of the nozzle <NUM> and an inner surface <NUM> of the shield cap <NUM>. For example, the flow rate of the second shield gas <NUM> may be <NUM>-<NUM> liters per minute ("l/min") (<NUM> - <NUM> cubic feet per minute ("cfm")). In some implementations, the flow rate may be <NUM>/min (<NUM> cfm). In some implementations, a ratio of the flow rate of the second shield gas to the flow rate of the first shield gas may be <NUM> to <NUM>.

Adding active gases to conventional TIG/GTAW torches typically cause the tungsten electrode to prematurely wear and/or oxidize, reducing the useful life of the tungsten. Therefore, with a conventional torch, any efficiency gained in the welding operation by adding an active gas are lost due to frequent replacement of the electrode. However, since the first the flow of shield gas <NUM> acts as a gas-curtain around the electrode <NUM>, the two flow system of the present embodiment avoids the premature wear and/or oxidization (e.g., that would otherwise be caused by active gas of shield gas <NUM>) of the conventional torches while improving weld penetration and quality as compared to conventional TIG/GTAW welding.

Referring to <FIG>, a method <NUM> for operating a TIG/GTAW torch <NUM>, according to an embodiment, is depicted. The method includes flowing a first gas through a first channel in a torch body in operation <NUM>; guiding the first gas to a first plenum fluidly coupled to the first channel in operation <NUM>; guiding the first gas from the first plenum through a nozzle fluidly coupled to the first plenum, the nozzle having a steep angle in operation <NUM>; generating, via the nozzle and plenum, a high-speed, laminar flow of the first gas along an outer surface of an electrode assembly concentric with the nozzle in operation <NUM>; flowing a second gas through a second channel in the torch body in operation <NUM>; guiding the second gas to a second plenum fluidly coupled to the second channel in operation <NUM>; and guiding a laminar flow of the second gas through a shield cap in operation <NUM>. Notably, in operations <NUM> and <NUM>, gas does not flow through a wall of a consumable part (e.g., the nozzle or shield cap), but flows through a cavity or opening defined by the consumable part, along an inner or outer surface of the respective consumable part.

The first gas is an inert gas, and the second gas is a mixture of an inert gas and one or more active gases. During a weld operation, the high-speed, laminar flow of the first gas prevents the second gas from contacting the electrode assembly. Thus, oxidation of the electrode is avoided.

The laminar flow of the second gas is generated, in part, by a back pressure that is built up in the torch body by the configuration of the second channel. As noted above and shown in <FIG> and <FIG>, the second channel <NUM> has a V-shape. The V-shape of the channel helps generate the back pressure in the second shield gas. A rectifier, disposed between the nozzle and shield cap, also increases the back pressure of the second gas and rectifies and diffuses the flow of the second gas before flowing through the shield cap and onto a workpiece.

In some implementations, the second gas may be an inert gas or mixture of inert gases e.g., argon and/or helium. In some implementations, one or more active gases (e.g., carbon dioxide, oxygen, hydrogen, nitrogen, etc.) may be added to the second gas. The active gases may impact the quality of the weld. As noted above, adding carbon dioxide to the second gas reduces the surface tension of the weld pool and reverses the Marangoni flow of the molten metal in the weld pool, providing greater weld penetration at lower temperatures as compared to TIG/GTAW welding with only inert gases. As a further example, adding nitrogen to the second gas controls the content of ferritic and/or austenitic stainless steel in a weld.

Referring to <FIG>, a conventional TIG/GTAW torch <NUM> is compared to torch <NUM>. In <FIG>, an arc <NUM> between the electrode <NUM>, according to an embodiment, and a work piece <NUM> is shown with an arc length of about <NUM>. Due to the high-speed, laminar flow <NUM> of the first shield gas <NUM>, an angle α between the outer edges of the arc <NUM> is relatively small even at the long arc length of <NUM>. For example, the angle α may be about <NUM> degrees. In <FIG>, a conventional TIG/GTAW torch <NUM> is shown. The conventional torch <NUM> includes a shield cap <NUM> and electrode <NUM>. During operation, an arc <NUM> between a conventional electrode <NUM> and a work piece <NUM> with an arc length of about <NUM> is shown. Though the arc length is half the length of the arc <NUM>, the angle β between the outer edges of the arc <NUM> is much larger. For example, the angle β may be about <NUM> degrees, almost double the size of arc <NUM>. Referring to <FIG>, a comparison between the arc <NUM> from electrode <NUM> and arc <NUM> from a conventional electrode <NUM> separated by cutaway line <NUM>. The constrained arc <NUM> from torch <NUM> according to the example embodiment provides better weld performance as compared to conventional torches <NUM>. Additionally, the conventional TIG/GTAW torch generates more heat resulting in an electrode having a higher temperature along the distal end. The two-gas torch <NUM> provides a constrained arc <NUM> that produces less heat while providing greater flexibility in useable arc lengths and improved weld penetration as compared to conventional TIG/GTAW torches <NUM>.

Claim 1:
An assembly (<NUM>) for a torch (<NUM>), characterized in that the assembly (<NUM>) comprises:
an electrode (<NUM>) comprising a first metal; and
an electrode holder (<NUM>) comprising:
a second metal different from the first metal;
a proximal portion (<NUM>);
a distal portion (<NUM>); and
a central portion (<NUM>) disposed between the proximal portion (<NUM>) and the distal portion (<NUM>), the central portion (<NUM>) comprising a plurality of radially extending protrusions (<NUM>);
characterised in that:
an angle between a longitudinal axis (<NUM>) of the assembly (<NUM>) and an outer surface (212A, 212B) of at least one of the electrode holder (<NUM>) and the electrode (<NUM>) is between about five degrees and about fifteen degrees, and
in that the electrode holder (<NUM>) is molecularly bonded to the electrode (<NUM>), wherein molecular bonding means that atoms and/or electrons of the electrode holder (<NUM>) interact with atoms and/or electrons of the electrode (<NUM>) to form the molecular bond; and
in that the first metal comprises tungsten and the second metal comprises copper.