阅读说明：本技术 机电线性致动电极 (Electromechanical linear actuation electrode ) 是由 A·雷蒙德 D·A·泰瑟姆 L·潘科尔 D·A·科特 G·H·帕特南 R·林诺 于 2018-06-14 设计创作，主要内容包括：本文的方法提供等离子体电弧焊炬,该等离子体电弧焊炬包括围绕电极的尖端,该电极具有近端和远端,以及围绕尖端的屏蔽件,该屏蔽件包括邻近电极的远端的出口孔。该焊炬还可以包括耦合到电极的线性致动设备,用于致动电极使得电极的远端相对于尖端和屏蔽件的出口孔轴向地移动。在一些方法中,线性致动设备能够操作为沿着延伸通过尖端的中心纵向轴致动电极。在一些方法中,线性致动设备可以包括以下之一：微型线性驱动马达、微型线性步进马达、音圈、螺线管圈和磁致伸缩致动器。在一些方法中,在焊炬的焊接或切割循环期间致动电极。(The methods herein provide a plasma arc torch including a tip surrounding an electrode having a proximal end and a distal end, and a shield surrounding the tip, the shield including an exit aperture adjacent the distal end of the electrode. The torch may further include a linear actuation device coupled to the electrode for actuating the electrode such that the distal end of the electrode moves axially relative to the exit aperture of the tip and shield. In some methods, the linear actuation device is operable to actuate the electrode along a central longitudinal axis extending through the tip. In some methods, the linear actuation device may include one of: a micro linear drive motor, a micro linear stepper motor, a voice coil, a solenoid coil, and a magnetostrictive actuator. In some methods, the electrode is actuated during a welding or cutting cycle of the torch.)

1. A plasma arc torch comprising:

a tip surrounding an electrode, the electrode having a proximal end and a distal end;

a shield surrounding the tip, the shield including an exit aperture adjacent the distal end of the electrode; and

a linear actuation device coupled to the electrode or the tip for actuating the electrode or the tip such that the distal end of the electrode moves axially relative to the exit aperture of the shield.

2. The plasma arc torch of claim 1, the linear actuation device operable to actuate the electrode or the tip along a central longitudinal axis extending through the tip.

3. The plasma arc torch of claim 1, the linear actuation device comprising one of: a micro linear drive motor, a micro linear stepper motor, a voice coil, a solenoid coil, and a magnetostrictive actuator.

4. The plasma arc torch of claim 1, further comprising an emissive insert disposed at the distal end of the electrode.

5. The plasma arc torch of claim 2, further comprising a nozzle having one or more fluid passages formed therein.

6. The plasma arc torch of claim 5, wherein the electrode is a stepped cathode and the nozzle is an anode, and wherein one or more channels formed within the anode provide gas to the stepped cathode.

7. The plasma arc torch of claim 6, wherein the one or more channels are oriented substantially perpendicular to the central longitudinal axis.

8. The plasma arc torch of claim 1, wherein the electrode is in contact with the tip during a start mode, and wherein the electrode is retracted from the tip during an operational mode.

9. A plasma arc system comprising:

a plasma arc torch comprising an electrode surrounded by a tip, the electrode comprising a proximal end and a distal end;

a shield surrounding the tip, the shield including an exit aperture adjacent the distal end of the electrode; and

a linear actuation device coupled to the electrode or the tip for adjusting a relative position between the electrode and the tip along a central longitudinal axis, wherein the central longitudinal axis extends through a central bore of the tip.

10. The plasma arc system of claim 9, the linear actuation device comprising one of: a micro linear drive motor, a micro linear stepper motor, a voice coil, a solenoid coil, and a magnetostrictive actuator.

11. The plasma arc system of claim 9, further comprising an emitter insert disposed within the distal end of the electrode.

12. The plasma arc system of claim 10, further comprising a nozzle, wherein the nozzle comprises one or more fluid passages formed therein.

13. The plasma arc system of claim 12, wherein the electrode is a stepped cathode and the nozzle is an anode, and wherein one or more channels formed within the anode provide gas to the stepped cathode.

14. The plasma arc system of claim 9 wherein the electrode is in contact with the tip during initiation of the arc, and wherein the electrode and the tip are retracted from each other during an operating mode.

15. The plasma arc system of claim 11, further comprising a control system operable with the linear actuation device, the control system including a sensor for determining at least one of: a voltage generated from the electrode, and a position of the distal end of the electrode relative to the exit aperture of the shield.

16. The plasma arc system of claim 15 wherein the sensor determines a position of the emissive insert.

17. The plasma arc system of claim 15, the control system further comprising a memory and a processor, wherein the processor detects degradation of the electrode by comparing historical electrode position data stored in the memory to a voltage generated from the electrode or a position of the distal end of the electrode.

18. A method, comprising:

providing a plasma arc torch comprising an electrode surrounded by a tip, the electrode comprising a proximal end and a distal end;

providing a shield surrounding the tip, the shield including an exit aperture adjacent the distal end of the electrode; and

actuating the electrode or the tip along a central longitudinal axis of a central bore extending through the tip by a linear actuation device.

19. The method of claim 18, further comprising actuating a emissive insert coupled with the distal end of the electrode relative to the shield.

20. The method of claim 18, further comprising receiving an output from a sensor operable with the plasma arc torch, the output comprising at least one of: a voltage generated from the electrode, and a position of the distal end of the electrode relative to the exit aperture of the shield.

21. The method of claim 20, further comprising:

retrieving historical electrode position data from memory;

comparing the output to the historical electrode position data; and

detecting degradation of the electrode when the output deviates from the historical electrode position data by a predetermined amount.

22. The method of claim 18, further comprising actuating the electrode using one of the following linear actuation devices: a micro linear drive motor, a micro linear stepper motor, a voice coil, a solenoid coil, and a magnetostrictive actuator.

23. The method of claim 18, further comprising actuating the electrode during a welding or cutting cycle of the plasma arc torch.

24. The method of claim 18, further comprising actuating the electrode axially along the central longitudinal axis during an arc initiation mode to bring the distal end of the electrode into contact with the tip.

25. The method of claim 18, further comprising actuating the tip axially along the central longitudinal axis during an arc initiation mode to bring the distal end of the electrode into contact with the tip.

Technical Field

The present disclosure relates generally to plasma arc torches and, more particularly, to apparatus and methods for linearly actuating an electrode of a plasma arc torch.

Background

Plasma devices, such as plasma arc torches, may be used to cut, mark (marking), fuse (gouging), and weld metal workpieces by directing a high energy plasma stream including ionized gas particles toward the workpiece. In a typical plasma arc torch, the gas to be ionized is supplied to the distal end of the torch and flows through the electrode and then out through an aperture in the nozzle or tip of the plasma arc torch. The electrode has a relatively negative potential and serves as a cathode. Instead, the torch tip has a relatively positive potential and acts as an anode. Further, the electrode is in spaced relation to the tip, thereby creating a gap at the distal end of the torch. In operation, a pilot arc is generated in the gap between the electrode and the tip, which heats and subsequently ionizes the gas. The ionized gas is then blown out of the torch and appears as a plasma stream extending distally away from the tip. As the distal end of the torch is moved to a position close to the workpiece, the arc jumps or transfers from the torch tip to the workpiece because the impedance of the workpiece to ground is lower than the impedance of the torch tip to ground. Thus, the workpiece acts as an anode, and the plasma arc torch operates in a "transferred arc" mode.

Current methods include fixed position electrodes that are not adjustable, or fixed position electrodes that may require partial disassembly of the torch that can only be changed by manually adjusting the electrode. For example, in current designs, a thread lock device may be used to secure the electrode retraction device (setback) to the chuck and the adjoining chuck body. With this design, adjusting the electrode retraction mechanism requires the torch to be shut down and the system to be subsequently restarted.

Disclosure of Invention

In view of the foregoing, in one method, a plasma arc torch includes a tip surrounding an electrode having a proximal end and a distal end, and a shield surrounding the tip, the shield including an exit orifice adjacent the distal end of the electrode. The plasma arc torch may further include a linear actuation device coupled to the electrode or tip for actuating the electrode or tip such that the distal end of the electrode moves axially relative to the exit aperture of the shield.

In another method, a plasma arc system includes a plasma arc torch having an electrode surrounded by a tip, the electrode including a proximal end and a distal end, and a shield surrounding the tip, the shield including an exit orifice adjacent the distal end of the electrode. The plasma arc system also includes a linear actuation device coupled to the electrode or the tip for adjusting a relative position of the electrode and the tip along a central longitudinal axis extending through the central aperture of the tip.

In yet another method, a method includes providing a plasma arc torch including an electrode surrounded by a tip, the electrode having a proximal end and a distal end. The method further includes providing a shield surrounding the tip, the shield including an exit aperture adjacent the distal end of the electrode, and actuating the electrode or the tip by a linear actuation device along a central longitudinal axis of the aperture extending through the tip.

Drawings

The figures illustrate exemplary methods of the disclosure, and wherein:

FIG. 1 is a cross-sectional side view of a plasma arc torch according to an exemplary embodiment of the disclosure;

FIG. 2 is a cross-sectional side view of the plasma arc torch of FIG. 1 in accordance with an exemplary embodiment of the disclosure;

3A-3B are cross-sectional side views of a welding operation of the plasma arc torch of FIG. 1 according to exemplary embodiments of the disclosure;

FIG. 4 is a side view of a linear actuation apparatus and a consumable of a plasma arc torch according to an exemplary embodiment of the disclosure;

FIG. 5 is a side view of a linear actuation apparatus and a consumable of a plasma arc torch according to an exemplary embodiment of the disclosure;

FIG. 6 is a side view of a linear actuation apparatus and a consumable of a plasma arc torch according to an exemplary embodiment of the disclosure;

FIG. 7 is a side view of a linear actuation apparatus and a consumable of a plasma arc torch according to an exemplary embodiment of the disclosure; and

fig. 8 is a flowchart illustrating an exemplary process according to an exemplary embodiment of the disclosure.

The drawings are not necessarily to scale. The drawings are merely representations, not intended to portray specific parameters of the disclosure. The drawings are intended to depict exemplary embodiments of the disclosure, and therefore should not be considered as limiting the scope. In the drawings, like numbering represents like elements.

Detailed Description

The present disclosure will now be continued with reference to the accompanying drawings, in which various methods are shown. However, it will be appreciated that the disclosed torch handle may be embodied in many different forms and should not be construed as limited to the methods set forth herein. Rather, these methods are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. In the drawings, like numbering represents like elements throughout.

As used herein, an element or operation recited in the singular and proceeded with the word "a/an" should be understood as not excluding plural elements or operations, unless such exclusion is explicitly recited. Furthermore, references to "a method" of the present disclosure are not intended to be interpreted as excluding the existence of additional methods that also incorporate the recited features.

Furthermore, spatially relative terms such as "below," "lower," "center," "above …," "upper," "over …," "above," etc., may be used herein to readily describe one element's relationship to another element(s) as illustrated in the figures. It will be understood that the spatially relative terms may encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.

Some examples may be described using the expression "coupled" and "connected" along with their derivatives. These terms are not necessarily intended as synonyms for each other. For example, descriptions using the terms "connected" and/or "coupled" may indicate that two or more elements are in direct physical or electrical contact with each other. The term "coupled," however, may also mean that two or more elements are not in direct contact with each other, but yet still co-operate or interact with each other.

As described above, in the cutting system of the related art, it is difficult to reliably start the arc and detect the end of life of the cathode and the nozzle. Existing plasma cutting systems using contact initiation provide contact between a cathode and an anode to initiate an arc to initiate the cutting process. The successful initiation of an arc in the system varies with the relative motion between the cathode and anode and the flow rate of the gas into the plasma chamber. The arc is generated by bridging the fixed gap between the cathode and anode with another conductor. The anode-cathode gap is created by increasing the gas pressure in the arc chamber until the conductor or moving cathode moves away from the anode and an arc is drawn between the cathode and the anode. The gas flow pushes the arc through the nozzle, thereby transferring the arc to the workpiece.

There is a balance between the mass flow of gas and the speed at which the cathode moves from the anode. In some cases, the arc may extinguish, or it will require so much power to sustain the arc that it may cause premature wear of the anode and/or cathode. Another problem with contact initiation is the use of standard air, which causes an oxide layer to build up on the anode and cathode and insulate the anode/cathode, causing premature end of life.

To address this need, embodiments herein provide a linearly actuated electrode/emissive element. Actuation of the emission element can control gas flow (e.g., gas pressure in the plasma chamber) and cathode position relative to the nozzle. This may allow the gas flow to vary with position and increase the ability to sustain a plasma arc for a wide variety of flow ranges by reducing the voltage requirements at any gap, while allowing the power supply to increase the current at any particular power level as the distance between the cathode and anode varies. Furthermore, for a given power level and/or current, the end of life may be determined by measuring the position of the emissive element relative to the cathode and anode.

Furthermore, cathode position sensing can be incorporated into the design to enable precise position control to be able to correlate cathode position with part wear and tear. Means for determining the position of the cathode may include linear and rotary potentiometers, Linear Variable Differential Transducers (LVDTs), absolute encoders, relative encoders, capacitive magnetic field sensors, magneto-optical field sensors, HAL magnetic field sensors, and other magnetic field sensors that change output voltage in response to a magnetic field.

Referring to fig. 1-2, a plasma arc torch (hereinafter "torch") 10 according to an embodiment of the disclosure will be described in more detail. As used herein, a plasma arc torch should be interpreted by one skilled in the art as a device that generates or uses plasma for whether manual or automatic cutting, welding, spraying, melting, marking, or the like. Accordingly, specific reference to a plasma arc cutting torch or a plasma arc torch should not be construed as limiting the scope of the present disclosure. Further, the specific reference to providing gas to a plasma arc torch should not be construed as limiting the scope of the present disclosure, as other fluids, such as, for example, liquids, may also be provided to a plasma arc torch in accordance with the teachings of the present disclosure.

As shown, the torch 10 includes one or more consumables 16, such as an electrode 100, a tip 102, and a shield or shield 114. The shield 114 may include an exit aperture 118 proximate a distal end 122 of the electrode 100. It will be appreciated that the welding torch 10 also typically includes other components, which are not shown for simplicity and ease of explanation. The torch 10 may further include a linear actuation device 120 coupled to the electrode 100 or the tip 102 for actuating the electrode 100 or the tip 102 such that a distal end 122 of the electrode 100 moves axially (e.g., linearly up/down) relative to the exit aperture 118 of the shield 114. More specifically, linear actuation device 120 is operable to actuate electrode 100 along a central bore extending through tip 102 and a central longitudinal axis "CA" of electrode 100. As will be described in more detail below, the linear actuation device 120 may include one of: a micro linear drive motor, a micro linear stepper motor, a voice coil, a solenoid coil, or a magnetostrictive actuator.

In some embodiments, the welding torch 10 may include a control system 125, the control system 125 being operable with the welding torch 10, e.g., with the linear actuation device 120 and/or the electrode 100. In particular, the control system 125 may include a sensor 127 configured to receive the voltage generated from the electrode 100, and/or to receive an indication of the position of the distal end 122 of the electrode 100 relative to the exit aperture 118 of the shield 114. In one example, sensor 127 may specifically monitor the position and/or size of the emissive insert of electrode 100. In some embodiments, the control system 125 may retrieve historical electrode position data from the memory 129 and then compare the received output to the historical electrode position data. Then, the control system 125 is configured to detect degradation of the electrode 100 if the output deviates from the historical electrode position data by a predetermined amount. Based on the level of degradation, end of life may be determined and/or predicted. This may be stored in the memory 129 and communicated to the operator of the welding torch 10.

In some embodiments, the control system 125 may be an expert system in the plasma arc torch 10 or in a remote computer. The control system 125 may include processing components for processing or performing logical operations of one or more components of the plasma arc torch 10. The processing components may include various hardware elements, software elements, or a combination of both. Examples of hardware elements may include devices, logic devices, components, processors, microprocessors, circuits, processor circuits, circuit elements (e.g., transistors, resistors, capacitors, inductors, and so forth), integrated circuits, Application Specific Integrated Circuits (ASIC), Programmable Logic Devices (PLD), Digital Signal Processors (DSP), Field Programmable Gate Array (FPGA), memory units, logic gates, registers, semiconductor device, chips, microchips, chip sets, and so forth. Examples of software elements may include software components, programs, applications, computer programs, application programs, device drivers, system programs, software developers, machine programs, operating system software, middleware, firmware, software components, routines, subroutines, functions, methods, procedures, software interfaces, Application Program Interfaces (API), instruction sets, computing code, computer code, code segments, computer code segments, linear code (words), values, symbols, or any combination thereof. Determining whether an example is implemented using hardware elements and/or software elements may vary in accordance with any number of factors, such as desired computational rate, power levels, heat tolerances, processing cycle budget, input data rates, output data rates, memory resources, data bus speeds and other design or performance constraints, as desired for a given example.

In some embodiments, the processing components may include general purpose computing elements, such as a multi-core processor, a co-processor, a memory unit, a chipset, a controller, a peripheral, an interface, an oscillator, a timing device, a video card, an audio card, a multimedia input/output (I/O) component (e.g., a digital display), a power supply, and so forth. Examples of memory units may include, but are not limited to, various types of computer-readable and machine-readable storage media in the form of one or more higher speed memory units, such as Read Only Memory (ROM), Random Access Memory (RAM), Dynamic RAM (DRAM), double data rate DRAM (DDRAM), Synchronous DRAM (SDRAM), Static RAM (SRAM), Programmable ROM (PROM), Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, polymer memory such as ferroelectric polymer memory, ovonic memory, phase change or ferroelectric memory, Silicon Oxide Nitride Oxide Silicon (SONOS) memory, magnetic or optical cards, arrays of devices such as Redundant Array of Independent Disks (RAID) drives, solid state memory devices (e.g., USB memory), Solid State Drives (SSD), and any other type of storage media suitable for storing information.

As shown in fig. 1, the linear actuation device 120 may move the electrode 100 distally toward the exit aperture 118, e.g., until the electrode 100 is in direct physical contact with the tip 102. As shown in fig. 2, the linear actuation device 120 may move the electrode 100 proximally away from the exit aperture 118 such that the gap between the electrode 100 and the tip 102 increases. During operation of the torch 10, the electrode 100 and the tip 102 may come into contact during the arc starting mode. Meanwhile, during the operation mode, the electrode 100 and the tip 102 may be separated from each other. Unlike previous designs that employed a fixed threaded rear clamp and collet, the disclosed embodiments allow the electrode 100 to move between a maximum retracted position and a minimum retracted position without shutting down the system. This may allow for changing the position of the electrode 100 relative to the tip 102 even during a welding cycle, which changes the focus of the welding arc, thereby enabling a change from a deep penetration type weld (i.e., a "keyhole" mode) to a soft surface fusion type weld (i.e., a "melt" mode) in operation.

Fig. 3A-3B illustrate the effect on the plasma shape from changing the retraction of the electrode 100. For example, FIG. 3A illustrates a maximum retracted position of the electrode 100 relative to the tip 102, which provides focused/deep penetration welding of the workpiece 130. Meanwhile, fig. 3B shows a minimum retracted position of the electrode 100, which corresponds to surface fusion welding of the workpiece 130. As stated above, a transition between each maximum and minimum retracted position is possible without cutting power to the torch 10.

In some embodiments, the control system 125 may be coupled with the amperage setting/control and gas of the welding torch 10. These settings may be variable within acceptable parameters and may be invoked by a job number or other identifier. This provides a more repeatable arc shape, as well as more precise gas and current control to further optimize arc characteristics for a particular material and/or joint design.

Referring now to FIG. 4, a side cross-sectional view of one or more consumables 216 of torch 210 will be described in greater detail. As shown, consumable 216 may include electrode 200, nozzle 204, and spacer 240. Torch 210 may also include a linear actuation device 220 coupled directly to electrode 200. As further shown, the spacer 240 may include one or more fluid channels 250 formed in the spacer 240 to permit gas flow through the consumable 216.

In some embodiments, electrode 200 may be made of a material susceptible to corrosion, such as tungsten, copper, a copper alloy, silver, or a silver alloy, hi addition, electrode 200 may define a bore at a distal end of electrode 200, which in some embodiments is configured to receive an emissive element 226, which emissive element 226 may be made of a material susceptible to corrosion, such as hafnium, a hafnium alloy, zirconium, a zirconium alloy, or other materials known in the art and having suitable properties.

In some embodiments, the linear actuation device 220 is a micro linear drive motor configured to actuate the emission element 226 to control the gas flow through the fluid channel 250 and/or the exit orifice 218, as well as to control the position of the anode (e.g., the electrode 200 and the emission element 226) relative to the cathode (e.g., the nozzle 204). This may allow the gas flow to vary with position and increase the ability to sustain a plasma arc for a wide variety of flow ranges by reducing the voltage requirements at any gap, while allowing the power supply to increase the current at any particular power level as the distance between the cathode and anode varies. The end life may be determined by measuring the position of the emissive element 226 relative to the nozzle 204 to maintain a power level at a given current. Actuation of the transmitting element 226 may enhance start-up by giving the torch 210 a method of removing an oxide layer by rapidly cycling the transmitting element 226.

Referring now to FIG. 5, a side cross-sectional view of one or more consumables 316 of the torch 310 will be described in greater detail.As shown, the consumables 316 may include a plurality of consumables that include the electrode 300, the nozzle 304, and the spacer 340. the torch 310 may also include a linear actuation device 320 that is directly coupled to the electrode 300. As further shown, the spacer 340 may include one or more fluid channels 350 formed in the spacer 340 to permit gas flow through the consumables 316. during use, the linear actuation device 320 may actuate the emissive element 326 a distance △ x/△ v relative to the outlet aperture 318 of the nozzle 304.

In this embodiment, the linear actuation device 320 includes a coil 352, the coil 352 configured to actuate the electrode 300 and the emissive element 326 to control gas flow through the fluid channel 350 and/or the exit orifice 318, as well as to control the position of the cathode 360 (e.g., the electrode 300 and the emissive element 326) relative to the anode 362 (e.g., the nozzle 304). For example, the linear actuation device 320 may be a voice coil or solenoid coil similar to an acoustic, loudspeaker, which may actuate the cathode with or without an electrical insulator between the driver (drive) and the emitting element 326. Using current drive of the coil to oppose the return element 354, such as a spring, the position of the cathode 360 can be determined by how much current is required to maintain the gas flow and arc voltage in place for a single or multi-step process.

In some embodiments, to set the initial starting position, the coil 352 may move the cathode 360 to an appropriate position (e.g., downward toward the nozzle 304) to close (close) the continuity circuit between the cathode 360 and the anode 362. If continuity is not detected, the coil 352 or solenoid may establish continuous oscillations multiple times until the oxide layer is broken or it is determined that the cathode 360 has worn back to a condition where electrical contact between the anode 362 and cathode 360 is not possible, thereby indicating end of life. In other embodiments, a magnetostrictive actuator may also be used to move the transmitting element 326 to achieve arc initiation. The magnetostrictive actuator operates by passing an operating or induced current through the coil 352 and expanding the electrode 300, thus moving the mechanical linkage to position the emitting element 326 away from the anode 362.

Referring now to FIG. 6, a side cross-sectional view of one or more consumables 416 of the torch 410 will be described in greater detail.

In this embodiment, the linear actuation device 420 comprises a linear stepper motor, which is provided with or without an electrical insulator between the driver and the firing element 426. Using the number of steps of the linear stepper motor, the position of the cathode 460 can be determined while in operation. For example, to set the initial starting position, a linear stepper motor may move the cathode 460 in an appropriate direction (e.g., linearly downward toward the exit aperture 418) by rotating the electrode 400 using external steps or threads 464 to close a continuity circuit between the cathode 460 and the anode 462 (e.g., the nozzle 404). If electrical continuity is not detected, the linear stepper motor may establish electrical continuity by: this is marked by end of life by multiple collations and engagements until the oxide layer is broken, or by determining that the cathode has worn back to a point where the gap between anode 462 and anode is so large that this electrical continuity cannot be achieved by moving cathode 460. To initiate an arc, there may be a feature in the plasma chamber that will open a gas port, allowing the gas flow into the plasma chamber to vary with the position of the cathode 460 relative to the anode 462.

Referring now to FIG. 7, a side cross-sectional view of one or more consumables 516 of torch 510 will be described in greater detail. As shown, consumable 516 may include electrode 500 and nozzle/spacer 504. Although not shown, the welding torch 510 may also include a linear actuation device coupled directly to the electrode 500. As further shown, the nozzle/spacer 504 may include one or more fluid channels 550 formed in the nozzle/spacer 504 to permit one or more gases to flow through the consumable 516. In this embodiment, the electrode 500 may be a stepped cathode having an external geometry that is complementary to the internal geometry of the nozzle/spacer 504, which is the anode. The fluid channel 550 is formed through the nozzle/spacer 504, for example, in an orientation perpendicular or substantially perpendicular to a central longitudinal axis extending through the electrode 500. In some embodiments, the gases (e.g., gas 1, gas 2, and gas 3) are configured as a stepped characteristic swirl flow (swirl) around the nozzle/spacer 504 and the electrode 500. By actuating the electrode 500 relative to the nozzle/spacer 504, the gas can be controlled as desired.

Referring now to fig. 8, a method 600 for actuating an electrode in a plasma arc torch in accordance with an exemplary embodiment will be described in more detail. The method 600 may include providing a plasma arc torch including an electrode surrounded by a tip, the electrode including a proximal end and a distal end, as shown at block 602. In one embodiment, the electrode includes a radiating element disposed at the distal end. In one embodiment, the electrode is a cathode and the tip is an anode.

The method 600 may also include providing a shield around the tip, the shield including an exit aperture adjacent the distal end of the electrode, as shown at block 604. The method 600 may also include actuating, by the linear actuation device, the electrode along a central longitudinal axis of the bore extending through the tip, as shown at block 606. In some embodiments, the method includes actuating the emissive insert relative to the shield. In some embodiments, the electrodes are actuated using one or more of the following linear actuation devices: a micro linear drive motor, a micro linear stepper motor, a voice coil, a solenoid coil, and a magnetostrictive actuator. In some embodiments, the method includes actuating the electrode during a welding or cutting cycle of the plasma arc torch. In some embodiments, the method includes actuating the electrode axially along a central longitudinal axis of a bore extending through the tip during an arc initiation mode to bring a distal end of the electrode into contact with the tip.

In some embodiments, the method 600 further includes receiving an output from a sensor operable with the plasma arc torch, as shown at block 608. In some embodiments, the output may be at least one of: the voltage generated from the electrode, and the position of the distal end of the electrode relative to the exit aperture of the shield. The method 600 also includes retrieving historical electrode position data from memory, as shown at block 610, and comparing the output to the historical electrode position data, as shown at block 612. The method 600 may also include detecting degradation of the electrode if the output deviates from the historical electrode position data by a predetermined amount, as shown at block 614.

Although the present disclosure has been described with reference to certain methods, many modifications, variations and changes to the described methods are possible without departing from the scope and ambit of the present disclosure as defined in the appended claims. Accordingly, it is intended that the disclosure not be limited to the described methods, but that it have the full scope defined by the language of the following claims, and equivalents thereof. Although the disclosure has been described with reference to certain methods, many modifications, variations and changes to the described methods are possible without departing from the spirit and scope of the disclosure as defined in the appended claims. Accordingly, it is intended that the disclosure not be limited to the described methods, but that it have the full scope defined by the language of the following claims, and equivalents thereof.