阅读说明：本技术 用于预热焊丝的系统、方法和设备 (System, method and apparatus for preheating welding wire ) 是由 杰克·茨魏尔 詹姆斯·李·于克尔 奎恩·威廉·沙尔特纳 于 2018-09-24 设计创作，主要内容包括：一种示例性焊接型系统包括：焊接型电源,其被配置为向焊接型电路提供焊接型电流,该焊接型电路包括焊接型电极和焊枪的第一接触末端；电极预热电路,其被配置为经由焊枪的第二接触末端提供流过焊接型电极的第一部分的预热电流；开关电路,其被配置为控制焊接型电源和第一接触末端之间的电流流动；以及预热控制电路,其被配置为控制开关电路以：选择性地将电流从焊接型电源引导到第二接触末端；以及选择性地将电流从电极预热电路转移到第一接触末端。(An exemplary welding-type system includes: a welding-type power supply configured to provide a welding-type current to a welding-type circuit comprising a welding-type electrode and a first contact tip of a welding gun; an electrode preheating circuit configured to provide a preheating current through a first portion of the welding-type electrode via a second contact tip of the welding torch; a switching circuit configured to control a current flow between the welding-type power supply and the first contact terminal; and a preheat control circuit configured to control the switching circuit to: selectively directing current from the welding-type power source to the second contact tip; and selectively transferring current from the electrode preheating circuit to the first contact tip.)

1. A consumable electrode feed welding-type system comprising:

a welding-type power supply configured to provide a welding-type current to a welding-type circuit comprising a welding-type electrode and a first contact tip of a welding gun;

an electrode preheating circuit configured to provide a preheating current through a first portion of the welding-type electrode via a second contact tip of the welding torch;

a switching circuit configured to control current flow between the welding-type power supply and the first contact tip; and

a preheat control circuit configured to control the switching circuit to:

selectively directing current from the welding-type power source to the second contact tip; and

selectively transferring current from the electrode preheating circuit to the first contact tip.

2. The welding-type system of claim 1, wherein the switching circuit comprises a switch, the preheat control circuit configured to enable the switch to conduct to transfer the current from the electrode preheat circuit to the first contact tip.

3. The welding-type system of claim 2, wherein the switching circuit further comprises a preheat voltage circuit configured to set a preheat voltage applied to the first portion of the welding-type electrode.

4. The welding-type system of claim 3, wherein the preheat voltage circuit comprises one or more diodes configured to conduct current in parallel with the first portion of the wire electrode and configured such that a total voltage drop of the one or more diodes sets the preheat voltage applied to the first portion of the welding-type electrode.

5. The welding-type system of claim 3, wherein the preheat voltage circuit comprises one or more resistors configured to conduct current in parallel with the first portion of the wire electrode and configured such that a total voltage drop across the one or more resistors sets the preheat voltage applied to the first portion of the welding-type electrode.

6. The welding-type system of claim 2, wherein the preheat control circuit comprises a pulse width modulation controller configured to control the switch using a pulse width modulation signal.

7. The welding-type system of claim 6, wherein the switching circuit is configured to apply a preheat voltage to the first portion of the welding-type electrode based on a duty cycle of the pulse width modulated signal.

8. The welding-type system of claim 1, wherein the preheat control circuit is configured to control the welding-type power source to output a target voltage.

9. The welding-type system of claim 8, wherein the preheat control circuit is configured to control the switching circuit in synchronization with control of the welding-type power supply.

10. The welding-type system of claim 9, wherein the preheat control circuit is configured to control the welding-type power supply to maintain a substantially constant current during transitions of the switching circuit.

11. The welding-type system of claim 9, wherein the preheat control circuit is configured to control the switching circuit to direct the current to the preheat circuit in response to at least one of a short circuit event or a short circuit clearing event.

12. The welding-type system of claim 1, further comprising a temperature sensor configured to measure a temperature representative of the first portion of the welding-type electrode, the preheat control circuit configured to control the switching circuit based on the temperature.

13. The welding-type system of claim 1, further comprising a voltage sensor configured to measure a preheat voltage across the first portion of the welding-type electrode, the preheat control circuit configured to control the switching circuit based on the preheat voltage.

Background

Welding is an increasingly common process in all industries. Welding is by its very nature only one way of joining two pieces of metal. Various welding systems and welding control schemes have been implemented for various purposes. In continuous welding operations, Metal Inert Gas (MIG) welding and Submerged Arc Welding (SAW) techniques allow a continuous weld to be formed by feeding an inert gas shielded welding wire from a welding gun. Such wire feed systems may be used in other welding systems, such as Tungsten Inert Gas (TIG) welding. Electrical power is applied to the wire and completed through the workpiece to maintain the wire electrode and workpiece molten to form a welding arc for a desired weld.

While very effective in many applications, these welding techniques can experience different initial weld properties based on whether the electrode is "cold" or "hot" at the start of the weld. In general, cold electrode onset can be considered to be the onset of the electrode tip and adjacent metal being at or relatively near ambient temperature. In contrast, thermode starts are typically those in which the temperature of the electrode tip and adjacent metal is greatly increased but below the melting point of the wire electrode. In some applications, it is believed that the initiation of the welding arc and weld is facilitated when the electrode is hot. However, the prior art does not provide a solution designed to ensure that the electrode is heated prior to initiating the welding operation.

Some progress has been made in the electrode preheating process. For example, U.S. patent publication No. 2014/0021183a1 to Peters describes a welding gun having a contact tip with electrically isolated upper and lower portions, each portion providing a portion of an aggregated welding current waveform. Similarly, U.S. patent nos. 4,447,703, 4,547,654, and 4,667,083 and PCT publication No. WO/2005/030422 describe various preheating techniques using dual contact tips. Despite the foregoing, there remains a need for improved welding strategies that allow weld initiation with heated wire electrodes to improve weld performance.

Disclosure of Invention

The present invention relates to a wire preheating system, method and apparatus for use with a welding gun, and more particularly, to a welding gun that enables a continuously fed wire electrode to be preheated for various forms of electric welding.

According to a first aspect, a welding system comprises: a contact tip assembly having a first contact tip portion and a second contact tip portion, wherein the first contact tip portion and the second contact tip portion are electrically isolated from each other (except by a wire electrode extending between the first and second contact tip portions), and each of the first contact tip portion and the second contact tip portion is in electrical contact with the same wire electrode during a welding operation; a first power supply operatively coupled to the first contact tip portion, the first power supply providing a welding current to the first contact tip portion during the welding operation; and a second power supply operatively coupled to the second contact end portion, the second power supply providing a preheating current during the welding operation, wherein the preheating current enters the wire electrode at the second contact end portion and exits at the first contact end portion, and wherein the welding current enters the wire electrode at the first contact end portion and exits via a welding arc at a weldment during the welding operation.

According to a second aspect, a contact tip assembly comprises: a first contact tip portion, wherein the first contact tip portion conducts a welding current provided by a first power supply during a welding operation; and a second contact tip portion, wherein the second contact tip portion conducts a preheating current provided by a second power supply during the welding operation, wherein the first contact tip portion and the second contact tip portion are electrically isolated from each other (except through a wire electrode extending between the first and second contact tip portions), and each of the first contact tip portion and the second contact tip portion is in electrical contact with the same wire electrode during the welding operation, wherein the preheating current enters the wire electrode at the second contact tip portion and exits at the first contact tip portion, and wherein the welding current enters the wire electrode at the first contact tip portion and exits via a welding arc at a weldment during the welding operation.

According to a third aspect, a welding method comprises: conducting a welding current provided by a first power supply via a first contact tip portion during a welding operation; conducting a preheat current provided by a second power supply via a second contact tip portion during the welding operation; electrically isolating the first contact end portion from the second contact end portion; and establishing electrical contact between the first contact tip portion and the second contact tip portion with the same wire electrode during the welding operation, wherein the preheating current enters the wire electrode at the second contact tip portion and exits at the first contact tip portion, and wherein the welding current enters the wire electrode at the first contact tip portion and exits via a welding arc at a weldment during the welding operation. In certain aspects, the method may further comprise: determining a preheating temperature of a portion of the wire electrode located between the first contact end portion and the second contact end portion, defining a determined preheating temperature; comparing the determined preheat temperature to a target pre-determined preheat temperature; and inhibiting the first power supply from providing the welding current to the first contact tip portion when the determined preheat temperature is greater than a predetermined deviation from a target predetermined preheat temperature. In certain aspects, the method may further comprise: calculating a voltage drop across the first contact end portion and the second contact end portion.

In certain aspects, the welding gun is a gooseneck welding gun.

In certain aspects, the torch is water cooled.

In certain aspects, the preheat current and the weld current are provided by the same power source.

In certain aspects, the welding system calculates a voltage drop across the first contact end portion and the second contact end portion.

In certain aspects, a dielectric waveguide is positioned between the first contact end portion and the second contact end portion.

In certain aspects, the temperature determining means determines a preheating temperature of a portion of the wire electrode located between the first contact end portion and the second contact end portion, thereby defining a determined preheating temperature.

In certain aspects, the temperature determining device is a thermometer.

In certain aspects, the temperature determining device is a non-contact infrared temperature sensor.

In certain aspects, the welding system compares the determined preheat temperature to a target predetermined preheat temperature, and disables the first power supply from providing welding current to the first contact tip portion when the determined preheat temperature exceeds the target predetermined preheat temperature by more than a predetermined deviation.

In certain aspects, the welding system compares a preheat voltage indicative of a wire temperature to a target predetermined preheat voltage indicative of a target temperature and prevents the first power supply from providing a welding current to the first contact tip portion that exceeds a predetermined current.

In certain aspects, the welding system has an upper current limit based on a specified voltage, and may have multiple upper current limits corresponding to different specified voltages. When the upper current limit is reached for a particular selected voltage, the welding system shuts down the weld or limits the current to the upper current limit.

In certain aspects, the wire feeder is configured to drive the wire electrode forward to feed the wire electrode and retract the wire electrode in a reverse direction.

In certain aspects, the wire feeder back drives the wire electrode to retract the wire electrode such that the distal end of the wire electrode is substantially at the first contact tip portion as part of the arcing algorithm.

In certain aspects, the wire feeder advances the wire electrode forward for a predetermined period of time after extinguishing the welding arc as part of an arc quenching routine.

Drawings

FIG. 1 illustrates an example robotic welding system.

FIG. 2a illustrates a side view of an example robotic gooseneck welding gun having an air-cooled preheater section.

FIG. 2b illustrates a cross-sectional side view of an example robotic gooseneck welding gun having an air-cooled preheater section.

FIG. 2c illustrates a perspective view of an example robotic gooseneck welding gun having a liquid-cooled welding cable.

FIG. 2d illustrates a perspective view with cross-section of an example robotic gooseneck welding gun having a liquid-cooled welding cable.

Fig. 3 illustrates a functional diagram of an exemplary contact tip assembly.

FIG. 4 illustrates a flow chart of an example process for providing a welding current based on a pre-heat temperature of a wire electrode.

FIG. 5 illustrates a flow chart of an example process for monitoring and adjusting the preheat temperature of a wire electrode.

Fig. 6a illustrates a timing diagram for an example weld initiation sequence.

FIG. 6b illustrates a flowchart of an example weld initiation sequence.

Fig. 6c illustrates a timing diagram for another example weld initiation sequence.

FIG. 6d illustrates a flow chart of another example weld initiation sequence.

FIG. 6e illustrates another example timing diagram for the example weld initiation sequence of FIG. 6 b.

FIG. 6f illustrates a flow chart of another example weld initiation sequence.

FIG. 7 illustrates a flow chart of an example weld control scheme.

Fig. 8a to 8d illustrate an example pulsed preheating power supply that can produce a pattern of preheating hot spots on the wire.

Fig. 9a to 9c illustrate preheating torches for various wire configurations.

Fig. 10a and 10b illustrate deposit test data.

FIG. 11 illustrates a functional diagram of another example contact tip assembly in which a power supply provides welding power to a wire electrode.

Fig. 12 illustrates a functional diagram of another example contact tip assembly in which the electrical connection between the preheat power supply and the contact tip is of opposite polarity relative to the connection in fig. 11.

FIG. 13 illustrates a functional diagram of another example contact tip assembly in which a power supply provides welding power to a wire electrode.

Fig. 14A illustrates a functional diagram of another example contact tip assembly in which a single power supply provides both preheating power and welding power to an electrode via a first contact tip and/or a second contact tip.

Fig. 14B illustrates another example contact tip assembly that enables a single power supply to provide current for preheating a wire electrode and to provide current for welding in accordance with aspects of the present invention.

Fig. 15 is a flow chart illustrating an example method for improving arc starting for welding using resistive preheating.

FIG. 16 illustrates an exemplary welding assembly using a parabolic reflector as part of the gas nozzle to reflect the arc to preheat the wire electrode extension.

FIG. 17 illustrates an example welding assembly including voltage sense leads for measuring a voltage drop across two contact tips for preheating a wire electrode.

FIG. 18 illustrates an example weld assembly including an enthalpy measurement circuit.

FIG. 19 illustrates an example embodiment of providing a resistively preheated wire to a workpiece and a separate arc source (such as a tungsten electrode) to melt the wire.

FIG. 20 illustrates an example embodiment of providing resistively preheated wire to a workpiece and providing a separate arc source (such as one or more laser sources) to melt the wire.

FIG. 21 illustrates example wire preheat current and/or voltage command waveforms for reducing or preventing soft preheated wire from being crushed and causing a blockage between the first contact tip and the second contact tip.

FIG. 22 is a flow chart illustrating an example method for improving arc initiation for welding using resistive preheating.

FIG. 23 illustrates an example user interface device that may be used to implement a user interface of a welding apparatus.

24A, 24B, and 24C illustrate example average heat inputs for different preheating levels.

FIG. 25 illustrates an example welding assembly using or including a user interface and welding control circuitry implementing a preheat control loop.

FIG. 26 is a block diagram of an example embodiment of the preheat control loop of FIG. 25.

FIG. 27 is a block diagram of example components used to monitor hydrogen content in a wire electrode and preheat a portion of the wire electrode to reduce hydrogen prior to welding.

Fig. 28 is a block diagram of an example embodiment of the power supply of fig. 2, 11, 12, 13, 14A, 14B, 17, 18, 25, and/or 27.

The drawings are not necessarily to scale. Wherever appropriate, the same or similar reference numbers will be used throughout the drawings to refer to similar or like elements.

Detailed Description

The invention relates to a system, method and apparatus for preheating a wire electrode. Preferred embodiments of the present invention are described in detail herein with reference to the following drawings. The same reference numbers will be used throughout the drawings to describe similar or analogous elements.

For the purposes of promoting an understanding of the principles of the claimed technology and presenting the best mode of operation with the understanding at present, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the claimed technology is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the claimed technology as illustrated therein being contemplated as would normally occur to one skilled in the art to which the claimed technology relates.

As used herein, the word "exemplary" means "serving as an example, instance, or illustration. The embodiments described herein are not limiting, but merely illustrative. It should be understood that the described embodiments are not necessarily to be construed as preferred or advantageous over other embodiments.

As used herein, the terms "circuits" and "circuitry" refer to physical electronic components (i.e., hardware) as well as configurable hardware, any software and/or firmware (code) executed by and/or otherwise associated with hardware. As used herein, for example, a particular processor and memory may include a first "circuit" when executing a first set of one or more lines of code, and may include a second "circuit" when executing a second set of one or more lines of code. As utilized herein, "and/or" means any one or more items in a list that are connected by "and/or". By way of example, "x and/or y" means any element of the three-element set { (x), (y), (x, y) }. In other words, "x and/or y" means "one or both of x and y". As another example, "x, y, and/or z" means any element of the seven-element set { (x), (y), (z), (x, y), (x, z), (y, z), (x, y, z) }. In other words, "x, y, and/or z" means "one or more of x, y, and z. As utilized herein, the word "exemplary" is meant to serve as a non-limiting example, instance, or illustration. As used herein, the terms "such as" and "e.g.," describe a list of one or more non-limiting examples, or illustrations. As utilized herein, a circuit is "operable" to perform a function whenever the circuit includes the hardware and code necessary to perform that function (if necessary), whether the performance of that function is disabled or not enabled (e.g., by operator-configurable settings, factory fine tuning, etc.).

As used herein, wire feed welding-type systems refer to systems capable of performing welding (e.g., Gas Metal Arc Welding (GMAW), Gas Tungsten Arc Welding (GTAW), etc.), brazing, cladding, case hardening, and/or other processes in which filler metal is provided by a wire fed to a work location, such as an arc or weld puddle.

As used herein, a welding-type power supply refers to any device (including but not limited to transformers-rectifiers, inverters, converters, resonant power supplies, quasi-resonant power supplies, switch-mode power supplies, etc.) capable of powering operations such as welding, cladding, plasma cutting, induction heating, laser (including laser welding and laser cladding), carbon arc cutting or drilling, and/or resistive preheating when power is applied thereto, as well as control circuitry and other ancillary circuitry associated therewith.

As used herein, preheating refers to heating the wire electrode before a welding arc and/or deposits occur in the travel path of the wire electrode.

A disclosed example consumable electrode feed welding-type system includes a welding-type power supply, an electrode preheating circuit, a switching circuit, and a preheating control circuit. The welding-type power supply provides a welding-type current to a welding-type circuit, wherein the welding-type circuit includes a welding-type electrode and a first contact tip of a welding gun. The electrode preheating circuit provides a preheating current through the first portion of the welding-type electrode via the second contact tip of the welding torch. The switching circuit controls current flow between the welding-type power source and the first contact terminal. The preheat control circuit controls the switching circuit to selectively direct current from the welding-type power supply to the second contact terminal and to selectively transfer current from the electrode preheat circuit to the first contact terminal.

In some examples, the switching circuit includes a switch, and the preheat control circuit enables the switch to conduct to transfer current from the electrode preheat circuit to the first contact terminal. In some such examples, the switching circuit further includes a preheat voltage circuit to set a preheat voltage applied to the first portion of the welding-type electrode. In some examples, the preheat voltage circuit includes one or more diodes to conduct current in parallel with the first portion of the wire electrode, and is configured such that a total voltage drop of the one or more diodes sets the preheat voltage applied to the first portion of the welding-type electrode. In some examples, the preheat voltage circuit includes one or more resistors configured to conduct current in parallel with the first portion of the wire electrode and configured such that a total voltage drop across the one or more resistors sets the preheat voltage applied to the first portion of the welding-type electrode.

In some examples, the preheat control circuit includes a pulse width modulation controller to control the switch using a pulse width modulation signal. In some such examples, the switching circuit applies the preheat voltage to the first portion of the welding-type electrode based on a duty cycle of the pulse width modulated signal. In some examples, the preheat control circuit controls the welding-type power supply to output the target voltage. In some such examples, the preheat control circuit controls the switching circuit in synchronization with control of the welding-type power supply. In some examples, the preheat control circuit controls the welding-type power supply to maintain a substantially constant current during transitions of the switching circuit. In some examples, the preheat control circuit controls the switching circuit to direct current to the preheat circuit in response to at least one of a short circuit event or a short circuit clearing event.

Some example systems also include a temperature sensor to measure a temperature representative of the first portion of the welding-type electrode, wherein the preheat control circuit is configured to control the switching circuit based on the temperature. Some examples further include a voltage sensor to measure a preheat voltage across the first portion of the welding-type electrode, wherein the preheat control circuit controls the switching circuit based on the preheat voltage.

Some disclosed examples describe conducting current "from" and/or to multiple locations in a circuit and/or power supply. Similarly, some disclosed examples describe "providing" current via one or more paths, which may include one or more conductive or partially conductive elements. The terms "from", "to" and "providing" as used to describe the conduction of electrical current do not define the direction or polarity of the electrical current. Conversely, even if example current polarities or directions are provided or described, these currents may still be conducted in either direction or with either polarity for a given circuit.

Referring to fig. 1, an example welding system 100 is shown in which a robot 102 is used, the robot 102 welding a workpiece 106 using a welding tool 108, such as the illustrated bent neck (i.e., gooseneck design) torch (or handheld torch when under manual control), to which a welding device 110 delivers power via a conduit 118 and returns power by way of a grounded conduit 120. The welding apparatus 110 may include, among other things, one or more power sources (each generally referred to herein as a "power supply"), a shielding gas source, a wire feeder, and other devices. Other devices may include, for example, water coolers, smoke exhaust, one or more controllers, sensors, user interfaces, communication devices (wired and/or wireless), and the like.

The welding system 100 of fig. 1 may form a weld (e.g., at the weld joint 112) between two components in a weldment by any known electric welding technique. Known electric welding techniques include Shielded Metal Arc Welding (SMAW), MIG, Flux Cored Arc Welding (FCAW), TIG, laser welding, sub-arc welding (SAW), stud welding, friction stir welding, and resistance welding, among others. MIG, TIG, hot wire cladding, hot wire TIG, hot wire brazing, multi-arc applications, and SAW welding techniques, among others, may involve automated or semi-automated external metal filling (e.g., via a wire feeder). In multi-arc applications (e.g., open arc or sub-arc), the preheater may preheat the wire to the puddle with an arc between the wire and the puddle. Alternatively, in any embodiment, the welding device 110 may be an arc welding device having one or more power supplies and associated circuitry that provide Direct Current (DC), Alternating Current (AC), or a combination thereof to the wire electrode 114 of a welding tool (e.g., the welding tool 108). The welding tool 108 may be, for example, a TIG torch, a MIG torch, or a flux cored torch (commonly referred to as a MIG "torch"). Wire electrode 114 may be a tubular electrode, a solid-type wire, a flux-cored wire, a seamless metal-cored wire, and/or any other type of wire electrode.

As will be discussed below, the welding tool 108 may employ a contact tip assembly 206 that heats the wire 114 prior to forming the welding arc 320 using the wire 114. Suitable types of wire electrodes 114 include, for example, tubular wire, metal-cored wire, aluminum wire, solid Gas Metal Arc Welding (GMAW) wire, composite GMAW wire, gas shielded FCAW wire, SAW wire, self-shielded wire, and the like. In one aspect, wire electrode 114 may employ a combination of a tubular wire and a reverse polarity current that increases metal transfer stability by converting the wire electrode from a metal ball to a flow jet. By preheating the wire before it exits the first tip and feeds into the arc (where the material transfer occurs), the tubular wire electrode 114 is more like a solid wire because the material transfer is a more uniform spray or stream spray. In addition, gassing events and very fine spatter causing events, which are typically seen when welding with metal-cored wires, may be reduced. This configuration enables the tubular welding wire to function in a similar manner to solid wire type flow-jet. Another benefit of preheating is that wire twist (more pronounced in tubular wires than in solid wires) due to poor wire casting and helical control in wire manufacturing is mitigated, as undesirable wire twist is reduced during the preheating phase.

As will be discussed with reference to fig. 2 a-2 d, the welding tool 108 may be a gooseneck welding gun, such as one used with robotic welding, although other shapes of welding guns are also contemplated, including almost any neck bend angle greater than zero, hand-held models for low-hydrogen FCAW welding, hand-held devices for GMAW, straight-neck hard automated spray guns, straight-neck SAW spray guns, and the like. FIG. 2a illustrates a side view of an example robotic gooseneck welding gun having an air-cooled preheater section. FIG. 2b illustrates a cross-sectional side view of an example robotic gooseneck welding gun having an air-cooled preheater section. FIG. 2c illustrates a perspective view of an example robotic gooseneck welding gun having a liquid-cooled welding cable. FIG. 2d illustrates a cross-sectional perspective view of an example robotic gooseneck welding gun having a liquid-cooled welding cable with copper conductors partially shown. In certain aspects, a plurality of ceramic guides or rollers may be used to provide a preheater having a bend therein, which may have the advantage of contacting the contact tip and allow for a unique form factor. In other aspects, the neck may be straight and the robot mounting bracket has a bend.

However, gooseneck torch designs offer a number of advantages. For example, the gooseneck torch design allows for better access to the weld joint 112, as well as automation capabilities in heavy equipment applications. The gooseneck torch design also allows for more dense deposits to be deposited in tighter spaces than, for example, an in-line torch design. Thus, in operation, the wire electrode 114 delivers a welding current to a weld point (e.g., the weld joint 112) on the workpiece 106 (e.g., weldment) to form the welding arc 320.

In the welding system 100, the robot 102, which is operably coupled to the welding device 110 via the conduit 118 and the ground conduit 120, controls the position of the welding tool 108 and the operation of the wire electrode 114 (e.g., via a wire feeder) by manipulating the welding tool 108 and triggering the start and stop of current flow (whether a pre-heat current and/or a welding current) to the wire electrode 114 by, for example, sending a trigger signal to the welding device 110. When the welding current flows, a welding arc 320 is formed between the wire electrode 114 and the workpiece 106, which ultimately produces a weldment. The catheter 118 and wire 114 therefore deliver a welding current and voltage sufficient to form a welding arc 320 between the wire 114 and the workpiece 106. At the point of welding between the wire electrode 114 and the workpiece 106, the welding arc 320 locally melts the workpiece 106 and the wire electrode 114 supplied to the weld joint 112, thereby forming the weld joint 112 as the metal cools.

In certain aspects, instead of a robotic arm of the robot 102, an operator may control the position and operation of the wire electrode 114. For example, the operator wears welding headwear and uses a handheld welding gun to weld workpiece 106, to which welding apparatus 110 delivers power via conduit 118. In operation, as with the system 100 of FIG. 1, the wire electrode 114 delivers current to a weld point on the workpiece 106 (e.g., weldment). However, the operator may control the position and operation of the wire electrode 114 by manipulating the handheld welding gun and triggering the start and stop of the current, for example, via a trigger. The handheld spray gun generally includes a handle, a trigger, a conductor tube, a nozzle at a distal end of the conductor tube, and a contact tip assembly 206 as disclosed herein. Applying pressure to the trigger (i.e., actuating the trigger) initiates the welding process by sending a trigger signal to the welding device 110, thereby providing a welding current, and activating the wire feeder as needed (e.g., driving the wire electrode 114 forward to feed the wire electrode 114 and retracting the wire electrode 114 in a reverse direction). For example, commonly owned U.S. patent No. 6,858,818 to Craig s.konoener describes an example system and method of controlling a wire feeder of a welding-type system. The present invention may be implemented with rotating arc and reciprocating wire feeds. In one example, the bottom tip may be moved to rotate the preheated wire. In another example, the welding wire may be moved axially forward and backward by an upstream reverse wire feed motor before being preheated. Both the rotary and reverse wire feeds themselves may have a positive effect on the wire melting rate and deposition. When they are combined, the effect on the deposition rate may be exacerbated.

FIG. 2A illustrates a perspective view of an example robotic gooseneck welding gun 108. The illustrated gooseneck torch 108 generally includes a torch body 202, a gooseneck 204 extending from a forward end of the torch body 202, and a contact tip assembly 206 at a distal end of the gooseneck 204 or through a radius of the gooseneck 204. The conduit 118 of the welding system 100 is operably coupled to the rear end of the torch body 202, the conduit 118 further operably coupled to the robot 102 and the welding equipment 110. The conduit 118 supplies, among other things, electrical current, shielding gas, and a consumable electrode (e.g., wire 114) to the torch body 202. The current, shielding gas, and consumable electrode travel through the torch body 202 to the gooseneck 204 and ultimately exit through an aperture at the distal end of the contact tip assembly 206 that ultimately forms the welding arc 320. In certain aspects, the gooseneck torch 108 may be fluid-cooled, such as air-cooled and/or liquid-cooled (e.g., water-cooled). In one embodiment, a liquid cooling mechanism surrounds the preheated contact tip and transfers additional heat away from a preheater inside the torch body.

To facilitate maintenance, the gooseneck torch 108 may be configured with interchangeable components and consumables. For example, the gooseneck torch 108 may include a quick change attachment and/or a second contact tip that allows for adaptation to existing water/air cooled torches. For example, commonly owned U.S. patent publication No. 2010/0012637 discloses a gooseneck locking mechanism suitable for use with a robotic welding gun having a gun body and a gooseneck including a connector receiver disposed in the gun body.

The enclosure for the preheated power source may take one of a variety of forms. In a preferred aspect, the preheating power supply may be integral with the welding power supply or inside the same housing. Inside the same box, the preheating power supply can be an auxiliary power supply with its own independent transformer, which is supplied from the mains; however, the preheating power supply may also share the same main winding and core of the transformer for the welding current by feeding from a dedicated secondary winding. The integrated box provides simplicity in interconnection, installation, and service. Another embodiment is that the preheat power supply is packaged separately in its own housing, which is beneficial for retrofitting into existing installations, and allows for "hybrid-mate" flexibility for pairing with other power sources, such as those suitable for bright arc welding and sub-arc welding. The individual packages also require communication between controllers within the welding power supply and within the preheat power supply. Communication may be provided through digital networking or more specifically an industrial serial bus, CANbus or ethernet/IP. The separate enclosure may also result in the power output of the preheating power source being combined with the output of the welding power source (possibly in the wire feeder or in a junction box in front of the welding gun or in the welding gun itself).

In open arc welding, there are two derivatives: high fusion welds (typically grooves, butt and fillet joints, travel speeds of 15 to 40 ipm) common in shipbuilding and heavy equipment manufacturing; and high speed welding (typically lap joints, 70 to 120ipm travel speed) common in automobiles. In both cases, preheating promotes deposition and/or travel speed. In open arcs, GMAW with solid or metal-cored wires may be used; alternatively, FCAW with flux cored wire may be used as the process. In sub-arc welding, solid or metal cored wires may be used. In both open arcs and subarcs, multiple wires and/or multiple arc combinations are possible. For example, the wire has been preheated and arcing, but the tail wire is preheated only without arcing. Another example is that both the lead and the tail have been preheated and arc started. Yet another example is that there are 3 welding wires, where both the first and third wires have been preheated and arc started, but the middle wire is preheated only without arc starting. Many permutations are possible. A third group of applications is resistive preheating with another non-self-fluxing heat source (such as laser, plasma or TIG) for welding, brazing, cladding and case hardening. The wire is preheated by resistive preheating and fed into a liquid bath melted by laser, plasma or TIG.

In some examples, the second contact tip (e.g., away from the arc) is spring-loaded (one size fits all contact tips). The spring pressure in the second contact tip improves the electrical contact despite galvanic corrosion and/or mechanical wear on the contact tip. Conventional spring-loaded contact tips are relatively expensive and are susceptible to damage from exposure to arcing and/or burn-back. However, using a spring-loaded second contact tip that is not exposed to arcing and not exposed to burn-back may extend the life of the spring-loaded contact tip. Because the welding gun accommodates different wire sizes and the multi-sized or universal second end increases the convenience of the welding operator by reducing the number of ends (e.g., first contact ends) that match the diameter of the welding wire. The configuration of the spring-loaded contact tip can be a single piece (e.g., a tubular structure with a slot, such that the tines accommodate different wire diameters and apply pressure and reliable contact) or two or more pieces. For a welding operator who is accustomed to a conventional torch and has only a single contact tip (e.g., the tip is closer to the arc), the welding operator has little or no need to replace the second contact tip, thereby enhancing the welding operator's experience with multiple contact tips.

Fig. 3 illustrates a functional diagram of an exemplary contact tip assembly 206 that may be used with the welding system 100, whether robotic or manual. As illustrated, the contact tip assembly 206 may include a first body portion 304, a gas shield inlet 306, a first contact tip 318, a second body portion 310, a third body portion 312, a ceramic guide 314, a gas nozzle 316, and a second contact tip 308. Although the first body portion 304, the second body portion 310, and the third body portion 312 are illustrated as separate components, one skilled in the art will recognize upon reading the present disclosure that one or more of the body portions 304, 310, 312 may be manufactured as a single component. In certain aspects, the contact tip assembly 206 may be added to an existing welding gun. For example, the contact tip assembly 206 may be attached to the distal end of a standard soldering apparatus and then used for resistive preheating. Similarly, the contact tip assembly 206 may be provided as a PLC retrofit with custom software, thereby enabling integration with existing systems already having a power supply and wire feeder.

In some examples, the first contact tip 318 and/or the second contact tip 308 are modular and/or removable to facilitate user servicing of the welding system 100. For example, the first contact end 318 and/or the second contact end 308 may be implemented as a replaceable cartridge. In some examples, welding apparatus 110 monitors and identifies one or more indications that first contact tip 318 and/or second contact tip 308 should be replaced, such as a measurement of time of use of first contact tip 318 and/or second contact tip 308, a temperature of first contact tip 318 and/or second contact tip 308, an intensity of current in first contact tip 318 and/or second contact tip 308 and/or the wire, a voltage between first contact tip 318 and/or second contact tip 308 and/or the wire, an enthalpy in the wire, and/or any other data.

In operation, the wire electrode 114 passes from the gooseneck 204 through the first contact tip 318 and the second contact tip 308, and between the first contact tip 318 and the second contact tip 308, the second power supply 302b generates a preheating current to heat the wire electrode 114. Specifically, the preheat current enters the wire electrode 114 via the second contact tip 308 and exits via the first contact tip 318. At the first contact tip 318, welding current may also enter the wire electrode 114. The welding current is generated by the first power supply 302a or is provided by the first power supply 302 a. The welding current exits the wire 114 via the workpiece 106, which in turn generates a welding arc 320. That is, the wire electrode 114 has a high potential when energized via a welding current to perform welding. When the wire electrode 114 is in contact with the target metal work piece 106, the circuit is completed and a welding current flows through the wire electrode 114, through the metal work piece 106 and to ground. The welding current melts the wire electrode 114 and the parent metal of the workpiece 106 in contact with the wire electrode 114, thereby engaging the workpiece as the melt solidifies. By preheating wire electrode 114, welding arc 320 may be generated with a sharp reduction in arc energy. When the distance between the electrodes is 5.5 inches, the preheat current may range from, for example, 75A to 400A. Generally, the preheat current is proportional to the distance between the two contact tips and the size of the wire electrode 114. That is, the smaller the distance, the more current is required. The preheat current may flow between the electrodes in either direction.

To avoid undesired kinking, buckling or blocking of the wire electrode 114, a guide 314 may be provided to guide the wire electrode 114 as the wire electrode 114 travels from the second contact tip 308 to the first contact tip 318. The lead 314 may be made of a ceramic, a dielectric material, a glass-ceramic polycrystalline material, and/or another non-conductive material. Contact tip assembly 206 may further include a spring-loaded device or equivalent device that reduces wire kinking, buckling, and jamming while increasing wire contact efficiency by keeping wire electrode 114 taught and/or straight.

In certain aspects, the second contact tip may be positioned at the wire feeder (e.g., at the welding device 110) or another extended distance to introduce the preheat current, in which case the preheat current may exit the contact tip in the gooseneck welding torch 108. The contact tip in the gooseneck torch 108 may be the same as or different from the contact tip that introduces the welding current into the wire electrode 114. The preheated contact tip may be further positioned along the wire electrode 114 to facilitate use with a push-pull torch such as that available from Miller Electric of Appleton, wisconsin. The lining can be made of ceramic rollers, so the preheating current can be reinjected at the wire feeder and has a very low value due to the length of the lining.

Welding current is generated by the first power supply 302a or provided by the first power supply 302a, while preheating current is generated by the second power supply 302b or provided by the second power supply 302 b. The first power supply 302a and the second power supply 302b may ultimately share a common power source (e.g., a common generator or line current connection), but the current from the common power source is converted, inverted, and/or regulated to produce two separate currents, a preheat current and a weld current. For example, the preheat operation may be facilitated using a single power supply and associated converter circuitry. In this case, three leads may extend from the auxiliary power line in the welding device 110 or welder, which may eliminate the need for the second power supply 302 b.

In certain aspects, instead of a unique contact tip assembly 206, the first contact tip 318 and the second contact tip 308 may be positioned on each side of the gooseneck bend. For example, as illustrated in fig. 2b, the preheat section may be curved (e.g., non-straight). That is, the welding wire is fed through a portion of the welding gun that bends more than 0 degrees or neck, which is known as a "gooseneck". The second contact tip 308 may be positioned before the initial bend and the first contact tip 318 is positioned after the bend terminates. Such an arrangement may increase the benefit of heated wire moving between the two contact tips through the connectivity of the neck portion. Such an arrangement results in more reliable connectivity between the two contact tips where dielectric inserts previously required off-axis tooling.

The preheating current and the welding current may be DC, AC, or a combination thereof. For example, the welding current may be AC and the preheating current may be DC, or vice versa. Similarly, the welding current may be DC electrode reverse connection (DCEN) or various other power schemes. In certain aspects, the welding current waveform may be further controlled, including constant voltage, constant current, and/or pulse (e.g., AccuPulse). In certain aspects, constant voltage and/or constant power, constant penetration, and/or constant enthalpy may be used instead of constant current to facilitate preheating. For example, it may be desirable to control the amount of penetration into the workpiece. In certain aspects, there may be variations in the contact tip to workpiece distance that, under a constant voltage welding process, will increase or decrease the welding current to maintain the voltage at or near the target voltage command, and thus vary the amount of penetration/heat input into the weld. By adjusting the amount of preheat current in response to changes in contact tip to workpiece distance, penetration/heat input can be advantageously controlled. Additionally, the penetration may be varied to reflect a desired weld/penetration profile. For example, the preheat current may be varied to a plurality of waveforms, such as, but not limited to, a pulse-type waveform, to achieve a desired weld/penetration profile.

The current may be line frequency AC delivered from a simple transformer under master phase control. Depending on how the control is implemented and the power supply configuration performed for this purpose, it may be simpler to control the current and voltage delivered to the preheat section using CC, CV or constant power. In another aspect, a welding power source for consumable arc welding (GMAW and SAW) may include regulating a constant welding current output and adjusting a wire speed to maintain an arc length or arc voltage set point (e.g., CC + V process control). In yet another aspect, the welding power supply can include regulating a constant welding voltage output (or arc length) and adjusting the wire speed to maintain an arc current set point (e.g., CV + C process control). The CC + V and CV + C process controls allow for wire stick out variations and preheat current/temperature variations to be accommodated by adjusting the wire feed speed (or variable deposits). In yet another aspect, the power source may include regulating a constant welding current output, the wire feeder maintaining a constant deposit, and the preheating power source adjusting the preheating current (or preheating power) to maintain a constant arc voltage (or arc length). It should be appreciated that the increase in preheat current/power adds a new degree of freedom to the wire welding process (GMAW and SAW) that allows flexibility and controllability in maintaining constant weld penetration and weld width (arc current), deposit (wire speed), and process stability (arc length or voltage). These control schemes may be switched during the welding process (e.g., CV + C is used for arc starting only, while other control schemes are used for main welding).

The use of advanced controlled welding waveforms allows for reduced heat input, distortion and weld geometry improvement at high deposition rates. Thus, the working range of pulse welding is expanded, the rotational transfer at a high deposition rate is reduced, and the spatter caused by the rotational spray is reduced. By preheating the wire electrode 114, the operating range of the pulse program can be extended to higher deposition. This is possible because the power required to transfer material at that deposition rate is lower. Previously, at higher deposition rates, the pulse width/frequency/peak current intensity was so high that the benefits of pulsing no longer existed. By preheating the wire electrode 114, the operator can use a similar pulse program to obtain a higher rate (e.g., 600 inches per minute (ipm)), which was previously only available at a lower rate (such as 300 ipm). Preheating the wire electrode 114 also maximizes the benefit of pulse welding with a low background current. In addition, the use of a metal core with a tailored pulse configuration in combination with the contact tip assembly 206 allows for denser deposition soldering at higher quality. By preheating wire electrode 114, wire electrode 114 behaves like a solid wire and its transfer pattern.

Additionally or alternatively, preheating the wire electrode 114 enables the background current of the pulse waveform to be substantially reduced as its primary function may change from growing a ball to merely maintaining an arc between the wire electrode 114 and the workpiece 106. Conventionally, the background current of the pulse waveform is used to grow droplets or balls that are subsequently deposited onto the workpiece 106. The example power supply 302a may implement a pulse waveform based on the preheat power applied to the wire electrode 114 by the preheat power supply 302 b.

The welding system 100 may be configured to monitor an exit temperature (e.g., a preheat temperature) of the wire electrode 114 between preheated contact tips (e.g., between the first contact tip 318 and the second contact tip 308, as illustrated). The preheat temperature may be monitored using one or more temperature determining devices, such as thermometers, located near the wire electrode 114, or otherwise operatively positioned to facilitate periodic or real-time welding feedback. Example thermometers may include both contact and non-contact sensors, such as non-contact infrared temperature sensors, thermistors, and/or thermocouples. The infrared thermometer determines the temperature from a portion of the thermal radiation emitted by the wire electrode 114 to obtain a measured preheat temperature. The temperature determining means may include one or more sensors and/or algorithms that calculate the pre-heat temperature of the wire electrode 114 in addition to or instead of a thermometer. For example, the system may dynamically calculate the temperature based on, for example, current or voltage. In certain aspects, the thermometer may measure the temperature of the dielectric waveguide or the first contact tip to infer the wire temperature.

In operation, an operator may set a target predetermined preheat temperature, whereby the welding system 100 dynamically monitors the preheat temperature of the wire electrode 114 and adjusts the preheat current via the second power supply 102b to compensate for any deviation (or other difference) of the measured preheat temperature from the target predetermined preheat temperature. Similarly, control may be set so that the welding operation cannot be performed until the wire electrode 114 has been preheated to a predetermined preheating temperature.

Fig. 4 illustrates a flow chart 400 of an example process for providing a welding current based on a pre-heat temperature of the wire electrode 114. The process begins at block 402 in response to, for example, activating the welding system 100 or receiving a trigger signal requesting the welding system 100 to provide a welding current to the wire electrode 114.

At block 404, the welding system 100 receives a trigger signal requesting the welding system 100 to supply a welding current to the welding tool 108 (e.g., to the wire electrode 114 via the first contact tip 318). The trigger signal may be digital or analog and provided in response to an output from the robot 102 or actuation of the trigger by an operator.

At block 406, the welding system 100 determines a pre-heat temperature of the wire electrode 114 using one or more sensors and/or algorithms of the temperature determination device to define the determined pre-heat temperature. The determined preheat temperature may be a measured preheat temperature or a calculated preheat temperature. For example, as discussed with reference to fig. 3, a thermometer may be positioned to determine the temperature of the portion of the wire electrode 114 between the first contact tip 318 and the second contact tip 308. The welding system 100 may also be configured to calculate the pre-heat temperature of the wire electrode 114 using one or more devices and/or algorithms, thereby eliminating the need for (or providing as an addition to) a thermometer. For example, in addition to heat generated by resistive heating at the overhang (e.g., the portion of the wire electrode 114 extending beyond the contact tip that introduces the welding current (e.g., the first contact tip 318 shown in the figures), the welding system 100 may employ internal circulation to calculate the preheat temperature of the wire electrode 114 based on the preheat current, voltage, and/or power supplied to the wire electrode. If a thermometer is also present, the measured preheat temperature may be compared to the calculated preheat temperature, and optionally used to train the algorithm.

The welding system 100 may determine the preheat temperature of the wire electrode 114 at predetermined intervals (e.g., between about 1 and 60 seconds, and more preferably between about 1 and 10 seconds) or dynamically (e.g., in real-time). The welding system 100 may further store the determined preheat temperature to a database, thereby enabling an operator to track, view, and analyze the determined preheat temperature over a given period of time, which may prove useful in identifying potential causes of defects.

At block 408, the welding system 100 determines whether the determined preheat temperature falls within a predetermined operable range of a target predetermined preheat temperature. That is, the predetermined operable range may allow for a predetermined deviation from the target predetermined preheat temperature. For example, if the predetermined deviation is set to 10% and the target predetermined preheat temperature may be X degrees, the predetermined operable range will be in the range from 0.9X to 1.1X. While a predetermined deviation of 10% is provided as an example, the predetermined deviation may be any deviation desired by the operator, and therefore should not be limited to 10%. In certain aspects, if the determined preheat temperature is consistently at the upper or lower limit of the predetermined operable range, an alert may be provided to an operator indicating that adjustment may be required. For example, if the determined preheat temperature is at the upper or lower limit of the predetermined operable range for a predetermined period of time (e.g., about 1 minute to 60 seconds, more preferably about 15 seconds to 60 seconds), a warning may be provided. If the welding system 100 determines that the determined preheat temperature falls within the predetermined operable range of the target predetermined preheat temperature, the process passes to block 412. If the welding system 100 determines that the determined preheat temperature falls outside of the predetermined operable range of the target predetermined preheat temperature, the process passes to block 410.

At block 410, the welding system 100 may adjust the preheat temperature of the wire electrode 114. The preheat temperature may be adjusted by increasing or decreasing the preheat current, power, and/or voltage supplied by the welding system 100 to the portion of the wire electrode 114 to be preheated. An example process for monitoring and adjusting the preheat temperature of the wire electrode 114 is described in more detail with respect to fig. 5.

At block 412, the welding system 100 supplies a welding current to the welding tool 108 to facilitate the welding operation. However, the temperature monitoring cycle may repeat until the trigger signal is no longer received by returning to block 404.

The current pulse may be used to calculate any voltage drop across the first contact end 318 and the second contact end 308, a process that may be integrated as part of a calibration routine. The welding system 100 may be configured to react (e.g., subtract) the voltage drop across the contact tips. For example, a1 millisecond current pulse (or energy pulse) may be used to determine the voltage drop. Additionally, the voltage drop may be determined by measuring two pulses to isolate the contact resistance from the wire resistance. This initial voltage measurement may be determined by the contact tip and the cold portion of the wire, which establishes a constant contact resistance and a resulting voltage drop across the contact that may be subtracted from the voltage drop across the preheat portion measured as the wire heats up. This then determines the resistance drop across the heated wire. Knowing the temperature coefficient of wire resistance, the average wire temperature can then be determined. Knowing the speed of the wire and the power being delivered to the wire, the peak wire temperature can be determined.

Fig. 5 illustrates a flow chart 500 of an example process for monitoring and adjusting the preheat temperature of the wire electrode 114. The process begins at block 502 in response to, for example, receiving a signal requesting that the welding system 100 provide a welding current to the wire electrode 114.

At block 504, the welding system 100 determines the preheat temperature of the wire electrode 114 using one or more sensors and/or algorithms substantially as discussed with respect to block 406 of fig. 4.

At block 506, the welding system 100 determines whether the determined preheat temperature falls within a predetermined operable range of a target predetermined preheat temperature, substantially as discussed with respect to block 408 of fig. 4. If the welding system 100 determines that the determined preheat temperature falls within the predetermined operable range of the target predetermined preheat temperature, the process returns to block 504, thereby effectively entering a loop. If the welding system 100 determines that the determined preheat temperature falls outside of the predetermined operable range of the target predetermined preheat temperature, the process passes to block 508.

At block 508, the welding system 100 determines whether the determined preheat temperature is greater than a predetermined operable range. The predetermined operable range may include a specified deviation from the predetermined preheat temperature. If the welding system 100 determines that the determined preheat temperature is greater than the predetermined operable range, the process passes to block 512. If the welding system 100 determines that the determined preheat temperature is not greater than the predetermined operable range, the process passes to block 510.

At block 510, the welding system 100 determines whether the determined preheat temperature is less than a predetermined operable range. If the welding system 100 determines that the determined preheat temperature is less than the predetermined operable range, the process passes to block 514. If the welding system 100 determines that the determined preheat temperature is not less than the predetermined operable range, the process proceeds to block 516 and optionally alerts the operator to the presence of a fault or error.

At block 512, the welding system 100 may increase the preheat temperature of the wire electrode 114. The preheat temperature may be increased by increasing the preheat current, power, and/or voltage supplied by the welding system 100 to the portion of the wire electrode 114 to be preheated. The predetermined current, power, and/or voltage may be increased at predetermined intervals (i.e., X amps, X watts, X volts, etc.) until the preheat temperature of the wire electrode 114 is determined to be within a predetermined operable range or at a target predetermined preheat temperature, which may be determined at block 504. In practice, an internal loop is established between blocks 504 and 508 until the preheat temperature is found at block 506 to be within a predetermined deviation of the target predetermined preheat temperature.

At block 514, the welding system 100 may reduce the preheat temperature of the wire electrode 114. The preheat temperature may be reduced by reducing the preheat current, power, and/or voltage supplied by the welding system 100 to the portion of the wire electrode 114 to be preheated. The predetermined current, power, and/or voltage may similarly be reduced at predetermined intervals (i.e., X amps, X watts, X volts, etc.) until the preheat temperature of the wire electrode 114 is determined to be within a predetermined operable range or at a target predetermined preheat temperature, which may be determined at block 504. In practice, an internal loop is established between blocks 504 and 510 until the preheat temperature is found at block 506 to be within a predetermined deviation of the target predetermined preheat temperature.

At block 516, the welding system 100 ends the process. The process may end due to, for example, a suspension signal, an error signal, or suspension of the welding operation (e.g., the welding system 100 is turned off, enters a standby mode, etc.).

Determining electrode extension may also be used to make heating adjustments to wire electrode 114. To ensure that the distal end of the wire electrode 114 is heated to the predetermined preheat temperature, the welding system 100 may be configured with an arc starting algorithm whereby the wire feeder pulls the wire electrode 114 in a reverse direction such that the distal end of the wire electrode 114 is substantially at the first contact tip 318, thereby heating the distal end of the wire electrode 114. This can be achieved by the following steps: the voltage drop between the contact tips is monitored until the wire is retracted out of contact with the first contact tip. The wire may then be slowly fed forward until contact. Preheating the wire electrodes 114 at the start and with the other arcing algorithms disclosed herein is beneficial because they produce high quality arcing and mitigate conventional arcing deficiencies, such as bar, multiple hard short events, lack of fusion/penetration, etc., which may occur at the non-preheated start.

Fig. 6a and 6b illustrate a timing diagram 600a and a flow chart 600b, respectively, of an example welding start sequence, in other words a routine for synchronized wire heating and feeding before the beginning of forming an arc. When the trigger is actuated, a low level of preheat current is generated and directed to the wire electrode 114 to begin heating the wire electrode 114. When the wire 114 reaches its desired lead-in speed, the preheat is then increased to a higher preheat level to accommodate the speed at which the wire 114 is moved. As understood by those skilled in the art, the lead-in speed is the speed at which the wire electrode 114 begins to feed before it contacts the workpiece. Generally, the lead-in speed is slower than the Wire Feed Speed (WFS), which aids in arcing and mitigates burn back. Once arcing is detected, the preheat current is increased at a predetermined rate, which is commensurate with the slope at which WFS reaches a specified speed. Once the desired WFS is reached, steady state heating occurs. For clarity, the increased or decreased current flow occurs through the preheating power supply rather than the welding power supply. The start routine may be executed in conjunction with a contact tip and workpiece distance prediction process. Once the welding device 110 has determined the current contact tip is a distance from the workpiece, the wire electrode 114 may be retracted so that the distal end of the wire electrode 114 is flush with the end of the contact tip. This will allow complete preheating of the electrode extension. The contact tip to work distance can be predicted during pulse welding or in CV-jet transfer mode by pulsing rapidly at the end of each weld being completed. Welding current feedback may also be used to determine changes in contact tip to work piece distance. For example, the welding current may be compared to a known welding current corresponding to one or more contact tip-to-work distances. The amount of preheat may then be increased or decreased based on the measured welding current feedback at a given wire feed speed. The voltage drop feedback may be used, among other things, for predictive maintenance (e.g., contact tip wear), capturing welding anomalies, providing alerts to an operator, generating initial wire electrode 114 temperature estimates, and/or adjusting a configuration or algorithm of the welding equipment 110. In certain aspects, the torch may be used in resistive preheat applications where there is no arc after the preheat section. Additionally, a handheld version of the torch may be used to burn out hydrogen in flux cored arc welding applications, as well as other situations where ultra low hydrogen is required. Accordingly, a hydrogen sensor may be added to the torch to monitor the amount of hydrogen burned out of the wire electrode 114 or entering the weldment.

Referring to fig. 6b, the example weld initiation process 600b may be initiated at block 602 by actuating a trigger of the welding gun. At block 603, welding device 110 determines whether the welding wire contacts both of the preheated contact tips. For example, if the welding wire is replaced, the welding wire may not contact both of the preheated ends. If the wire contacts both of the preheated contact tips (block 603), welding device 110 may retract wire electrode 114 a predetermined distance at block 604. If the welding wire does not contact both of the preheated contact tips (block 603), then at block 614, the welding device 110 is fed forward until contact is first detected.

If the welding device 110 detects a spike in the wire drive motor current, the welding device 110 may stop retracting the wire electrode 114 at block 616, otherwise the process continues to block 608. At block 608, the welding device 110 determines whether there is a loss of connection with respect to the first contact tip. If the connection is not lost, the process returns to block 602. If the connection is lost, the process proceeds to block 610 where the wire electrode 114 stops retracting. After stopping the wire retraction at block 610, or after feeding forward at block 614, the welding apparatus determines whether the wire contacts both preheated contact tips at block 612. If the wire does not contact both contact tips (block 612), control returns to block 614 to continue feeding forward. By retracting and/or feeding the wire, welding apparatus 110 may ensure that the distal end of wire electrode 114 is at the first electrode (reducing stick out). Once the connection to the first electrode is reestablished, a low temperature preheat is applied to the wire electrode 114 secured between the two contact tips at block 618. At block 620, the welding apparatus 110 begins driving the wire electrode 114 at the lead-in speed while feeding it with the pre-heat current. At block 622, the welding device 110 detects arcing between the wire electrode 114 and the weldment, after which the welding device 110 reaches steady state welding conditions and WFS. The process may terminate at block 626 (e.g., upon release of the trigger).

In some examples, after the low-current preheating is initiated at block 612, the welding device 110 pauses wire feed to allow the heating effect of the low-current preheating to melt through the wire and reduce the length of the wire that is actually cold (e.g., below a threshold temperature). In some examples, after beginning the low current preheat at block 612, the welding apparatus repeats blocks 604, 606, 608, and 610 at a slower forward feed speed (e.g., slower than the nominal lead-in speed) and a slow retract speed such that the length of the cold wire extending beyond the first contact tip is reduced (e.g., minimized). The first iteration of blocks 604, 606, 608, and 610 may be performed at a higher speed, and the second iteration may be performed at a slower wire feed speed to improve accuracy. The wire feed pause may also stop the wire feed more quickly before preheating the wire.

In the context of laser welding with resistive preheating (e.g., no arc) and/or laser brazing with resistive preheating, it may be desirable to reduce or minimize the "cold wire" portion and/or to reduce or minimize the cycle time at the start of the process. Cold wire refers to an un-preheated wire that extends beyond the bottom (first) contact tip.

In some examples, blocks 604, 610, and 612 may be used to preset the wire extension prior to arcing. This sequence may be performed between robot welding cycles or when the robot is not welding. By moving the wire back and forth between the two tips to determine the exact wire end position, the welding apparatus feeds the wire beyond the bottom end by a distance that is slightly below the contact tip-to-work distance (CTWD) of the taught position of the arcing robot ready for the next arcing. Due to the short distance wire stroke for arc starting, the actual wire lead-in speed and lead-in time (or cycle time) may be reduced (e.g., minimized).

FIG. 6c is a timing diagram 600c illustrating another example routine for synchronizing wire heating and feeding prior to beginning to form an arc. In timing diagram 600c, the wire is not advanced until the target wire preheat temperature and/or a wire preheat voltage indicative of the wire preheat temperature is reached. When the preheat target is met, a preheat control cycle (e.g., a voltage controlled weld control cycle (e.g., constant voltage) and/or a current controlled weld control cycle (e.g., constant current)) controls the preheat voltage and/or preheat current. When the preheat target is met, wire feed is initiated using the lead-in wire speed.

Referring to fig. 6d, an example weld start procedure 600d corresponding to the timing diagram of fig. 6c may be initiated at block 632 by actuating a trigger of the welding gun. At block 634, the welding apparatus 110 performs a low temperature wire preheat. If the welding device 110 detects at block 636 that the target wire preheat temperature and/or the target preheat voltage have not been reached, control returns to block 634. When the target wire preheat temperature and/or target preheat voltage is reached at block 636, the welding device 110 begins to import wire feed at block 638. At block 640, the welding device 110 controls the preheat current using a voltage controlled welding control cycle (e.g., constant voltage) and/or a current controlled welding control cycle (e.g., constant current). At block 642, the welding apparatus 110 detects arcing between the wire electrode 114 and the weldment. At block 644, the welding device 110 reaches steady state welding conditions and WFS. The process may terminate at block 646 (e.g., upon release of the trigger).

Fig. 6e illustrates an example timing diagram 600e for another example weld initiation sequence. The timing diagram 600e and welding start sequence of fig. 6e are similar to the timing diagram 600a and start sequence depicted in fig. 6a, except that the timing diagram 600e illustrates the loss of contact between the wire and the first contact tip while the wire is retracted prior to preheating, and then the wire is advanced to reestablish contact between the wire and the first contact tip.

Referring to fig. 6f, the example weld initiation process 600f may be initiated at block 650 by actuating a trigger of the welding gun. At block 652, the welding device 110 determines whether a connection between the preheated contact tips is detected. If a connection between the preheated contact tips is detected (block 652), at block 654 the welding device 110 retracts the wire at a first retraction speed (e.g., speed 1). At block 656, the welding apparatus 110 determines whether a threshold increase in wire drive motor current is sensed. If no increase in the threshold of wire drive motor current is sensed (block 656), the welding apparatus determines whether a loss of connection between the preheated contact tips is sensed at block 658. When a loss of connection between the preheated contact tips is not detected (block 658), control returns to block 654 to continue to retract the wire. On the other hand, when a loss of connection between the preheated contact tips is detected (block 658), the welding device 110 stops retracting the wire at block 660.

After the wire stops retracting (block 660), or if no connection between the preheated contact tips is detected (block 652), the welding equipment is fed forward at a first forward speed (e.g., speed 1) at block 662. At block 664, the welding device 110 determines whether a connection between the preheated contact tips is detected. If a loss of connection between the preheated contact tips is not detected (block 664), control returns to block 662 to continue wire feed.

When a connection between the preheated contact tips is detected (block 664), the welding device retracts the wire at a second retraction speed (e.g., a slower speed than the first retraction speed) at block 666. At block 668, the welding device determines whether a loss of connection between the preheated contact tips is sensed. Upon detecting no loss of connection between the preheated contact tips (block 668), control returns to block 664 to continue to retract the wire. On the other hand, when a loss of connection between the preheated contact tips is sensed (block 668), the welding device stops wire retraction at block 670.

At block 672, the welding equipment is fed forward at a second feed speed (e.g., a slower speed than the first feed speed). At block 674, the welding apparatus 110 determines whether a connection between the preheated contact tips is detected. If a connection between the preheated contact tips is not detected (block 674), control returns to block 672 to continue wire feed.

When the welding device senses a threshold increase in wire drive motor current (e.g., at least a threshold increase in wire drive motor current) (block 656), the welding device 110 determines whether the current spike is an immediate or fast spike at block 676. For example, if the current increases at a rate above a threshold slew rate, and/or if the current increases above the threshold current in less than a threshold time, an immediate or rapid spike may be considered. If the current spike is an immediate or fast spike (block 676), then the welding equipment identifies an error at block 690. The process may terminate at block 692 (e.g., upon release of a trigger or upon identification of an error at block 690).

If the current increase is not an immediate or rapid spike (block 676), then at block 678, the welding device 110 stops wire retraction.

After the wire stops retracting (block 678) and/or after a connection between the contact tips is detected (block 674), a low temperature preheat (e.g., a low current preheat) is applied to the wire 114 secured between the two contact tips at block 680. At block 682, the welding device 110 pauses the forward feed of the welding wire 114 until a target parameter (e.g., temperature, voltage, etc.) is reached. At block 684, the welding apparatus 110 begins driving the wire electrode 114 at the lead-in speed while feeding the wire electrode 114 with the pre-heat current. At block 686, the welding device 110 detects arcing between the wire electrode 114 and the weldment, after which the welding device 110 reaches steady state welding conditions and WFS at 688.

FIG. 7 illustrates a flow chart 700 of an example weld control scheme. The resistive preheat weld process is monitored to allow for a constant heat input process. During the welding process, if something in the arc path causes the welding current to exceed the predetermined set current, the welding device 110 will adjust the preheat setting to maintain the predetermined set current, thereby maintaining a constant heat output from the welding arc. A similar process can be performed to account for welding current drops. The process can be adjusted for a constant penetration pattern, whereby the welding current can be maintained while the preheating current is adjusted, allowing for a constant penetration depth. In one aspect, a coordinated mode may be employed in which the operator does not have to decide on any other than normal welding parameters, and the preheat conditions will be fully coordinated and self-adjusting. In other example modes, the end user may have some control over the occurrence of the warm-up condition. In operation, an operator may set, for example, a desired amount of preheat, a desired penetration level, a desired heat input level, and the like.

Referring to fig. 7, the example weld initiation process 700 may be initiated at block 702 by actuating a trigger of a welding gun. At block 704, the welding device 110 begins steady state welding (e.g., block 624 of fig. 6 b), which may occur after the start sequence is ended. At block 706, the welding device 110 performs welding at a predetermined pre-heat temperature, current, voltage, impedance, power, and/or enthalpy. For example, the predetermined preheating temperature is 800 degrees celsius. At block 708, the welding device 110 monitors welding current feedback to maintain a predetermined preheat temperature and/or current. If the welding current and/or voltage is too low, the welding device 110 reduces the preheat current at block 712. Conversely, if the welding current and/or voltage is too high, the welding device 110 increases the preheat current at block 710. The process continues until the process terminates, for example, when the trigger is released.

The welding system 100 may be configured with an arc quenching routine that allows for elimination of micro-welding from the contact tip to the wire electrode 114. The arc quenching routine may include one or more steps including, for example, continuing to move the welding wire forward and/or backward after the welding arc 320 is quenched. Thus, as part of the arc quenching routine, after the welding arc 320 is quenched, the wire feeder drives the wire electrode forward and/or backward to feed the wire electrode for a predetermined time period or a predetermined distance. In addition, the preheat current may also be ramped down (i.e., decreased) at a slower rate to avoid rapid solidification within the conductive tip.

Forming the preheat control based on weld feedback and/or reach (such as those used in arc starting and arc quenching routines) reduces overall downtime that may result from excessively preheated wire feed and welding issues, as well as makes the system easier for effective calibration and use by the end user.

Finally, the welding system 100 may be configured with an emergency shutdown routine (or program). In an emergency shutdown routine, energy may be managed at the time of an emergency power loss to avoid wire electrode 114 breakage due to excessive preheating. For example, the preheat current may be switched off, or reduced below a predetermined emergency preheat current value. Managing the arc interruption routine (e.g., particularly during the emergency shutdown routine) avoids clogging and microwelding formation of the wire electrode 114 in the outermost contact tip, thus resulting in a reduced overall downtime of the welding system 100 and generally resulting in a more inclusive process (e.g., allowing for increased deflection).

Referring to fig. 8a to 8d, the preheat power supply 302b may be of a low cost capacitor discharge type, and the preheat is provided as a train of heat pulses to provide a series of hot spots in the wire electrode 114 before it enters the contact tip 318. In another embodiment, the power supply may be a switch mode power supply capable of delivering high and narrow pulses (e.g., 1000A for 1 ms). The objective is to create a series of pre-heating hot spots in the wire extension so that the hot spots reach liquidus temperatures before the portion of the wire preceding them. The solid wire slug may separate at the hot spot. This can significantly increase the melting rate at the same average welding current. In an embodiment, the energy stored in the capacitor may be discharged into a load with little circuit inductance, such as having the capacitor located near the two contact ends. The capacitor charging circuit may be located remotely from the contact tip, such as, for example, housed inside the wire feeder or main welding power supply, with the cable within the torch compound cable completing the circuit that preheats the energy storage device. One embodiment is to have a 1mm gap between the contact ends 308 and 318. This produces a very high but short current pulse to overheat a length of wire (e.g., 1mm long) just before it enters the bottom end, so the wire is fully supported to avoid buckling. After the hot spot leaves the bottom end, it will be further heated by the extension resistive joule heating and eventually accumulate enthalpy and reach the melting point, while the previous wire has not. In one embodiment, the wire is fed at a constant speed. In another embodiment, the wire feed is temporarily stopped when capacitor discharge occurs to prevent the wire from melting at the sliding physical contact with the contact tips 308 and 318 due to contact resistance.

The following paragraphs pertain to: a capacitor discharge circuit is used to create a transient high, but very fast (e.g., less than 1 millisecond, typically tens of microseconds) current spike (e.g., more than 500A, typically more than 1,000A, or more than 5000A). Referring to fig. 6a, the capacitor bank is positioned very close to the torch body, possibly at the rear end of the torch body itself, so that the parasitic inductance of the contact tip is minimized. The capacitor is charged by a charging circuit to hold energy. A semiconductor switch (e.g., SCR) releases stored energy into the contact tips, causing the wire bond between the tips to "overheat" and form hot spots. Since the preheated hot spots pass the bottom end and continue to be heated by extended joule heating as they approach the arc. The hot spot closest to the arc may melt before the solid wire in front of it, and the liquid is squeezed by the lorentz force of the welding current, and a "slug" of unmelted wire may fall into the puddle. This will greatly increase the deposition rate.

Refer to fig. 8 b. The power supply is connected to the bottom end instead of the top end. This may minimize interference between the welding circuit and the capacitor discharge circuit. Referring to FIG. 8c, the preheating power source may be a DC or AC power source with CV, CC, or constant power output, essentially warming the wire to a certain percentage near but below the melting temperature. Referring to fig. 8c and 8d, the capacitor discharge circuit is used as a pulse welding power supply, but at much higher peak current levels can generate a very large lorentz force to squeeze the liquid at the wire extension just before the tip of the wire extension reaches the arc. The time for the capacitor to discharge is important and it is desirable to catch the liquid at the tip of the wire extension during the downward oscillation (in oscillation) of the wire extension. Referring to fig. 8d, it only requires one terminal and both power supplies are connected to the same terminal. This may simplify the design. The welding power supply may be a constant current, constant voltage, or DC pulse output. In the case of a pulsed output from the welding power supply, the capacitor discharge circuit discharges at the end of the pulse. During the welding pulse, the size of the liquid at the wire extension tip increases such that at the end of the welding pulse, a very high current peak with a large lorentz force is applied for liquid separation. Another situation is where the welding pulse is a series of small pulses, but the last pulse contains a capacitor discharge super pulse to facilitate separation.

Referring again to fig. 8c and 8d, the capacitor discharge circuit may facilitate arcing. During the arc starting sequence, the preheat energy storage capacitor may be pre-charged and the switch turned on as the wire is fed toward the workpiece at the lead-in speed. On the first contact between the welding wire and the workpiece, the capacitor can discharge through an incomplete contact and its high contact resistance. The rapid rise in current from the discharge results in a more brittle and reliable arc strike than a high current arc strike by the welding power supply that overcomes the inductance requirements of the weld cable.

In another embodiment, the contact tip may be located in front of the gooseneck, and a high temperature but electrically insulating liner may be embedded inside the gooseneck to direct the welding wire toward the torch tip. This may result in a very long wire extension (substantially the entire linear gooseneck length) to facilitate heating of the wire extension without the gas shield loss, wire upset, etc. problems associated with conventional long extension welding. Yet another embodiment may use the copper shoe shaped lumen of the gooseneck to deliver welding current, instead of delivering welding current at a single point as in conventional contact tubes (holes), gradually delivering welding current on a sliding curved surface, such that welding current is gradually delivered from the copper shoe to the wire (through infinite points).

In some other examples, the second contact tip 308 is positioned inside the wire feeder, in front of the power pin of the welding gun, to conduct welding current to the first contact tip 318 near the arc, such that the welding wire is preheated at a low preheating current for the entire length of the welding gun between the wire feeder and the first contact tip 318. The wire gradually heats up as it passes from the wire feeder toward the front of the gun.

As illustrated in fig. 9a to 9c, the preheat torch may be used in combination with a single preheat wire, a tandem preheat wire (two power sources), and/or a submerged arc welding power supply in a dual preheat wire configuration (one power source). For example, fig. 9a illustrates a Submerged Arc (SAW) power supply in a single pre-heated wire configuration. The wire may be preheated with CV AC, CV EP, CV EN, CV + C AC, CV + C EP, CV + C EN, CC AC, CC EP, CC EN, CC + V AC, CC + V EP, and/or CC + V EN. FIG. 9b illustrates a submerged arc power supply in a series preheated wire configuration. The wire bond may be used in a standard SAW configuration or any of the variations mentioned above. The wire may be preheated with CV AC, CV EP, CV EN, CV + C AC, CV + C EP, CV + C EN, CC AC, CC EP, CC EN, CC + V AC, CC + V EP, and/or CC + V EN. In certain aspects, 1 wire may be preheated and one wire (front and back) remains normal. In addition, different polarity combinations (EP, EN, AC, CV + C, CC + V) may be used for each wire. For some applications, one example series SAW configuration in fig. 9b is DCEP on unheated solid wire for penetration and DCEN on resistively preheated metal cored wire for deposition from the arc. Finally, FIG. 9c illustrates a submerged arc power supply in a single preheated wire configuration. The wire may be preheated with CV AC, CV EP, CV EN, CV + C AC, CV + C EP, CV + C EN, CC AC, CC EP, CC EN, CC + V AC, CC + V EP, and/or CC + V EN.

The results of the tests in CV EP, EN and AC are summarized in fig. 10a and 10 b. The results show a reduction in heat input and/or an increase in deposition of roughly 20% to 30% in most cases. The results also show that as the heat input is reduced, the penetration is reduced (as shown in fig. 10 a). The results of testing EP, EN and AC in CV + C mode showed that deposition increased by 20% to 25% as the wire feed speed increased to maintain the desired amperage. The penetration in this case is almost the same as for non-pre-heat welding of the same amperage (i.e. fig. 10 b). The tests were carried out in all cases using metal-cored and solid welding wires. Welding tests also show that the disclosed example resistive preheat system can produce a heat input reduction/deposition increase effect equivalent to an electrical protrusion of 5 inches or more.

Fig. 11 illustrates a functional diagram of another example contact tip assembly 1100. The contact tip assembly 1100 is similar to the assembly 206 illustrated in fig. 3. The assembly 1100 includes a power supply 302a to provide welding power (e.g., for generating a welding arc 320 or other welding power transfer) to the wire electrode 114. The assembly 1100 also includes a power supply 302b to generate a preheat current to heat the wire electrode 114.

The assembly includes a first contact end 318 and a second contact end 308. As described above with reference to fig. 3, the preheat power supply 302b has the same electrical connections with the second contact terminal 308 and the first contact terminal 318. Instead of the welding power supply 302a being electrically connected with the first contact tip 318 (e.g., via a positive polarity connection) and the workpiece 106 (e.g., via a negative polarity connection) illustrated in fig. 3 above, the welding power supply 302a is electrically connected to the second contact tip 308 via a positive polarity connection and to the workpiece 106 via a negative polarity connection.

In the example assembly of fig. 11, the preheat power supply 302b provides a preheat current to a portion of the wire electrode 114 between the contact tips 308, 318, which may occur before and/or during welding. In operation, the welding power supply 302a provides a welding current to support the arc 320. In the configuration of fig. 11, the energy provided by the welding power supply 302a also preheats the wire electrode 114 between the second contact tip 308 and the arc 320. In some examples, the preheat power supply 302b supplies power to preheat the wire electrode 114 in conjunction with energy provided by the welding power supply 302a, thereby reducing power delivered by the welding power supply 302 a.

Fig. 12 illustrates a functional diagram of another example contact tip assembly 1200. The assembly 1200 is similar to the assembly 1100 of FIG. 11. However, the electrical connections between the preheat power supply 302b and the contact tips 308, 318 are reversed relative to the connections in fig. 11. In other words, the preheat power supply 302b is electrically connected to the second contact terminal 308 via a negative polarity connection and to the first contact terminal 318 via a positive polarity connection.

In the example assembly 1200, when the welding power supply 302a is not supplying power (e.g., when not welding), the power supply 302b may provide preheating power to the portion of the wire between the contact tips 308, 318. When the welding power supply 302a provides welding power to the assembly 1200, the preheating power supply 302b is turned off and/or is used to reduce a portion of the welding power provided by the welding power supply 302a to control preheating of the wire electrode 114 by the welding power supply 302 a.

Fig. 13 illustrates a functional diagram of another example contact tip assembly 1300. The assembly 1300 includes a power supply 302a to provide welding power (e.g., for generating a welding arc 320 or other welding power transfer) to the wire electrode 114. The assembly 1300 also includes a power supply 302b to generate a preheat current to heat the wire electrode 114. The welding power supply 302a is electrically connected to the first contact tip 318 (e.g., via a positive polarity connection) and the workpiece 106 (e.g., via a negative polarity connection).

In the assembly 1300 of fig. 13, the preheating power supply 302b is electrically connected to the wire electrode 114 such that the welding current provided by the power supply 302a does not overlap the preheating current provided by the preheating power supply 302b on the wire. To this end, the example assembly 1300 includes a third contact end 1302, the preheat power supply 302b being electrically connected to the third contact end 1302. Although fig. 13 illustrates an example in which the preheat power supply 302b is electrically connected to the third contact tip 1302 via a positive polarity connection and to the second contact tip 308 via a negative polarity connection, in other examples, the connection polarities are opposite.

Fig. 14A illustrates a functional diagram of another example contact tip assembly 1400. The assembly 1400 includes a single power supply that provides both preheating power and welding power to the wire electrode 114 via the first contact tip 318 and/or the second contact tip 308. To control the direction of preheating and/or welding power to the contact tips 308, 318, the assembly 1400 includes a preheat/weld switch 1402. The preheat/weld switch 1402 switches the electrical connection between the welding power supply 302a and the first contact tip 318, the second contact tip 308, and/or the workpiece 106.

The welding power supply 302a provides preheating to the wire electrode 114 by, for example, controlling the preheat/weld switch 1402 to connect the positive terminal of the welding power supply 302a to one of the contact tips 308, 318 and the negative terminal of the welding power supply 302a to the other of the contact tips 308, 318. The welding power supply 302a provides preheating to the wire electrode 114 by, for example, controlling the preheat/weld switch 1402 to connect the positive terminal of the welding power supply 302a to one of the workpiece 106 or the contact tips 308, 318 and the negative terminal of the welding power supply 302a to the other of the workpiece 116 or the contact tips 308, 318 (e.g., based on whether DCEN or DCEP is used).

If the preheat/weld switch 1402 connects one terminal of the welding power supply 302a to the second contact tip 308 and connects the other terminal of the welding power supply 302a to the workpiece 106, the welding current supplied by the welding power supply 302a also provides preheat to the wire electrode 114. In some examples, preheat/weld switch 1402 alternates between the following modes: the welding power supply 302a is connected to a first set of electrical connections for preheating the wire electrode 114 (e.g., to the contact tips 308, 318), to a second set of electrical connections for welding (e.g., to the workpiece 106 and the first contact tip 318), and/or to a third set of electrical connections for simultaneously preheating the wire electrode 114 and welding (e.g., to the workpiece 106 and the second contact tip 308).

Fig. 14B illustrates another exemplary contact tip assembly 1450 that enables a single power source (e.g., power source 302a) to provide current for preheating wire electrode 114 and to provide current for welding. The exemplary contact tip assembly 1450 includes a power source 302 a. A first terminal of the power source 302a is coupled to the second contact tip 308.

The contact tip assembly 1450 includes a switching circuit 1452 and a preheat control circuit 1454, the switching circuit 1452 controlling the current flow between the first terminal of the power supply 302a and the first contact tip 318. The example switch circuit 1452 of fig. 14B includes a switch 1456 and a preheat voltage circuit 1458.

A switch 1456 (e.g., a MOSFET or other type of transistor, relay, etc.) may be turned on or otherwise controlled to conduct to couple the second contact terminal 308 and the first terminal of the power supply 302a to the first contact terminal 318. When enabled, the switch 1456 may provide an alternative and/or lower impedance path from the first terminal of the power source 302a to the first contact tip 318, rather than a path through the second contact tip 308 and the wire electrode 114. The weld control circuitry controls the example switch 1456 to direct current to the second contact tip 308 to preheat the wire electrode 114 or to divert current to the first contact tip 318 (e.g., bypassing the preheating circuit).

The preheating voltage circuit 1458 sets an upper preheating voltage (e.g., V) to be applied to preheat the wire electrode 114 when the switch 1456 is controlled to be turned off_d). If power supply 302a outputs a voltage higher than the upper preheat voltage, preheat voltage circuit 1458 clamps the voltage at V_dAnd the remaining current is diverted to the first contact terminal 318. The example pre-heat voltage circuit 1458 includes a plurality of diodes configured in series such that the diodes conduct current from the second contact end 308 to the first contact end 318 when forward biased. The number of diodes determines the upper preheat voltage. When the power supply 302a outputs a voltage lower than the upper preheating voltage, the voltage output by the power supply 302a is the preheating voltage applied to the wire electrode 114. However, the preheat voltage circuit 1458 may be implemented using other devices, such as zener diodes, resistors, and/or any other suitable circuit elements. For example, the preheat voltage circuit 1458 may include one or more resistors to conduct current in parallel with the portion of the wire electrode 114 between the contact tips 308, 318 such that the total voltage drop across the one or more resistors sets the preheat voltage applied to the portion of the welding-type wire electrode 114.

When the switch 1456 is controlled to be turned on, the preheating voltage applied to the wire electrode 114 is a voltage (e.g., V) across the switch 1456_sw). In some examples, the voltage across switch 1456 is a low voltage to reduce (e.g., minimize) losses at switch 1456 and increase (e.g., maximize) current shunting through switch 1456 and away from second contact tip 308.

In the example of fig. 14B, the preheat control circuit 1454 includes a PWM controller 1460 to control the switch 1456 using a PWM signal. The example PWM controller 1460 may adjust V by controlling the duty cycle of the PWM signal_dAnd V_swAn effective preheat voltage in between. For example, a higher (or lower) duty cycle may increase the application of a higher preheat voltage (e.g., up to V) to the wire electrode 114_d) While a lower (or higher) duty cycle may increase the application of a lower preheat voltage (e.g., V) to the wire electrode 114 (e.g., increasing preheat)_sw) Time (e.g., reduced warm-up).

The warm-up control circuit 1454 may receive a temperature measurement from the temperature sensor 1462 and/or a voltage measurement from the voltage sensor 1464. The temperature sensor 1462 measures the temperature of the portion of the wire electrode 114 being preheated (e.g., positioned adjacent to the wire electrode 114, or operably positioned, using one or more temperature determining devices, such as a thermometer, to facilitate periodic or real-time welding feedback, including contact sensors and non-contact sensors, such as non-contact infrared temperature sensors, thermistors, and/or thermocouples). The voltage sensor 1464 measures a preheat voltage on the preheated first portion of the wire electrode 114. The preheat control circuit 1454 (e.g., via the PWM controller 1460) may control the switching circuit based on temperature feedback and/or voltage feedback. The contact tip assembly 1450 may include any other type and/or number of sensors.

In addition to controlling switch 1456 to control the preheat voltage, exemplary preheat control circuit 1454 may provide voltage and/or current commands to exemplary power supply 302a to control the output voltage and/or output current from power supply 302 a. The example preheat control circuit 1454 may cause the power source 302a to output a first voltage (e.g., a desired welding voltage) when the preheat control circuit 1454 controls the switch 1456 to be on and a second voltage (e.g., a desired preheat voltage) when the preheat control circuit 1454 controls the switch 1456 to be off.

In some examples, the preheat control circuit 1454 controls the welding-type power supply 302a to maintain a substantially constant current during the transition of the switch circuit 1456 to open or closed. For example, an inductance associated with the output of power supply 302a may produce an abrupt decrease and/or increase in the output voltage in response to the closing or opening of switch 1456. Although the control loop of power supply 302a may correct the voltage in a timely manner, the output current may substantially and undesirably increase or decrease during the correction process. To maintain a substantially constant current during the transition of the switch 1456, the example preheat control circuit 1454 commands the power supply 302a to increase or decrease the output voltage substantially in synchronization with controlling the switch 1456 transition. The commanded output voltage change may be predetermined and/or determined based on a circuit inductance (which is known or estimated by the preheat control circuit 1454), for example, the preheat control circuit 1454 may command the power supply 302a to increase voltage in synchronization with turning off the switch 1456 and command the power supply 302a to decrease voltage in synchronization with turning on the switch 1456.

Additionally or alternatively, the preheat control circuit 1454 may control the switch 1456 to direct current to the preheat circuit (e.g., open) in response to a short circuit event (e.g., a time period between a voltage decrease below a short circuit threshold and a voltage increase above the short circuit threshold) and/or a short circuit clearing event (e.g., a time period between a current start increasing to clear a short circuit and a voltage increase above the short circuit threshold). The warm-up control circuit 1454 may predictively (e.g., based on a plurality of feedback factors) and/or reactively (e.g., based on an increase in identification voltage) determine that the short circuit is about to clear. In some examples, the preheat control circuit 1454 controls the switch 1456 to direct current to the preheat circuit immediately prior to short circuit clearing, which increases resistance in the welding circuit and thus reduces current in the welding circuit when the arc is re-established. By directing current to the preheat circuit prior to short circuit clearing, the preheat control circuit 1454 may reduce spatter caused by short circuit clearing events.

Fig. 15 is a flow chart illustrating an example method 1500 of using resistive preheating to improve arc starting for welding. The method 1500 may be used with any of the example components 206, 1100, 1200, 1300, 1400, 1450 of fig. 2, 11, 12, 13, 14A or 14B. Generally, the example method 1500 preheats the wire electrode 114 and verifies that the wire electrode 114 is at a high temperature prior to contacting the workpiece to initiate an arc (e.g., via an operator, an automated system, etc.). When the wire electrode 114 has a higher temperature, arc ignition may be easier because the initial contact resistance is generally higher.

The method 1500 begins at block 1502 in response to, for example, activating the welding system 100 or receiving a trigger signal requesting the welding system 100 to provide a welding current to the wire electrode 114. At block 1504, the welding system 1000 determines a target arcing voltage threshold (e.g., corresponding to a temperature to which the wire electrode 114 is to be preheated prior to striking an arc). At block 1506, the welding system 100 applies a preheat current to the wire electrode 114 (e.g., via the welding power supply 302a and/or the preheat power supply 302 b).

At block 1508, the welding system 100 determines whether the wire electrode voltage is within a threshold deviation of the target arcing preheat temperature. For example, the welding system 100 may use sensors and/or thermal models to measure or infer wire electrode temperature. If the wire electrode temperature is not within the threshold deviation of the target arcing voltage (block 1508), the method 1500 returns to block 1506 to continue applying the preheat current to the wire electrode 114. Additionally, method 1500 does not allow for wire advancement. The wire voltage indicates the resistance in the wire, which also indicates the preheat temperature of the wire. When the wire electrode temperature is within a threshold deviation of the target arcing voltage (block 1508), the system 100 enables welding current to flow to the wire electrode 114 (e.g., enables welding). At block 1512, the method 1500 ends.

Some examples involve performing one or more pre-weld passes using a pre-heated wire electrode to lay filler material in the joint to be welded (e.g., first laying metal in the joint as a "pre-deposit" in the absence of an arc). Examples include performing one or more passes with an arc (e.g., TIG and/or MIG), plasma, and/or laser to melt the pre-deposited material into the joint to perform welding after the pre-deposition pass. In other words, the pre-deposited material may be laid down like hot and soft "glue" and the skin adhered to the workpiece, which may be performed with or without a weave pattern. The joint may be a square joint, a butt joint, a groove joint, a fillet joint, or any other type of joint. The pre-deposition pass and the weld pass may occur alternately for multiple passes of welding. Additionally or alternatively, the pre-deposition passes and/or the weld passes may have a non-uniform number (e.g., lay-up of 2 pre-deposition passes followed by 1 weld pass). The pre-deposition passes may be performed using different weave patterns between the pre-deposition passes (e.g., one pre-deposition pass on the left, one pre-deposition pass on the right, and then a greatly dithered weld pass to fuse the two previous pre-deposition passes). The weld pass may be performed with or without a filler metal. If the welding pass is performed without filler metal (e.g., TIG, plasma, and/or laser), the pre-deposition and welding operations may be completed at different stations with physical spacing between the deposition and welding steps, which may enable improved process control, production flexibility, less distortion, and/or less dilution of the base metal. In some examples, a wire electrode resistively preheated by two adjacently positioned contact tips is used to deposit preheated filler metal directly into a molten pool formed by a laser, electron beam, or plasma arc on a workpiece.

In some examples, the wire electrode preheating methods and systems disclosed herein are used in combination with a rotating arc for submerged arc applications to increase material deposition and/or welding speed. In addition, spatter, which is typically associated with rotating arc technology, is contained under the flux used for submerged arc welding, enabling improved weld appearance and adequate weld penetration.

FIG. 16 illustrates an exemplary welding assembly 1600 that uses a parabolic reflector 1602 as part of the gas nozzle 316 to reflect an arc to preheat an extended portion of the wire electrode 114. The example parabolic reflector 1602 is configured to direct light generated by the welding arc 320 to a small area of the wire electrode 114 near the welding arc 320. In the example of fig. 16, the preheat power supply 302b is omitted, but the preheat power supply 302b may be included to provide additional preheating when a welding arc is not present.

In some examples, after the welding system 100 detects the end of the arc welding process (e.g., the release of the torch trigger) and after the arc power and the preheat power cease, the welding system 100 controls the wire feed motor to retract the wire electrode 114 by an amount of the distance between the at least two contact tips to retract the preheated portion of the wire electrode 114 past the second contact tip 318. The preheating of wire 114 and the retraction of the softened portion makes it easier for the operator to pull the wire portion from a potential blockage in the welding gun rather than forcing the operator to move the wire by squeezing.

FIG. 17 illustrates an example welding assembly 1700 that includes voltage sense leads 1702, 1704 for measuring a voltage drop across the two contact tips 308, 318 for preheating the wire electrode 114. Preheat monitor 1706 monitors for heating anomalies by comparing the measured voltage to a threshold voltage level, by evaluating a time derivative and/or an integral of the measured voltage, and/or by statistical analysis (e.g., average, standard deviation, Root Mean Square (RMS) value, etc.). Additionally or alternatively, warm-up monitor 1706 monitors the stability of the voltage for a longer-term history (e.g., over minutes and/or hours). Additionally or alternatively, preheat monitor 1706 monitors preheat current, preheat power, and/or preheat circuit impedance via preheat power supply 302 b.

Some example welding systems 100 use radiant heating to heat the wire electrode 114 via the wire liner. Examples include constructing a coiled wire liner using nichrome, platinum, and/or another suitable material to both physically support and/or guide the wire electrode 114 from the wire supply to the welding gun and to simultaneously heat the wire electrode 114. The wire liner is heated by the example preheat power supply 302 b. A shorter portion of the wire liner may be heated using a higher heating current, and/or a longer portion of the wire liner (e.g., a majority of the wire liner extending from the wire feeder to the welding gun) may be heated using a reduced heating current. Wire 114 is progressively heated by the wire liner using radiant heating such that wire 114 has an elevated temperature before wire 114 reaches the torch and/or first contact tip 318.

Additionally or alternatively, the welding system 100 may use infrared heating lamps mounted within the torch body to preheat the wire electrode 114. The infrared heating lamps are powered by a preheat power supply 302 b.

The disclosed examples may be used to perform cladding operations with reduced dilution of the substrate. In such an example, the preheat power supply 302b provides high preheat power to preheat the wire to near melting. The welding power supply 302a then provides a relatively low arc current (e.g., 15A to 20A) to bring the wire end to the actual melting point. However, some such examples use a fast response motor to oscillate the wire because the relatively low current (e.g., 15A to 20A) may not be sufficient to cause the melted wire to break to transfer the liquid metal through the arc. The swinging of the welding wire swings down or swings down the liquid metal at the tail end of the welding wire. An example of such an oscillation technique is illustrated by Y.Wu and R.Kovacevic in Proceedings of the institute of Mechanical Engineers Vol 216 Part B: "Mechanically assisted droplet transfer in gas Metal arc welding" process in the gas Metal arc welding "is described in J Engineering Manufacture, p.555,2002, which is incorporated herein by reference. By using a low arc current, the example cladding method reduces base metal dilution and/or reduces the cost of methods such as laser cladding.

In some other examples, the cladding system uses resistive preheating of the wire electrode and a laser energy source to lay down the cladding. The laser beam may be defocused and there is no welding arc (e.g., an arc) during the cladding operation. In some cases, welding arcing is prevented via a voltage clamping system that clamps the voltage between the welding wire and the workpiece to less than the arc initiation voltage. Such clamping systems may include diodes and/or transistors.

In some examples, welding-type devices may be used to perform metal additive manufacturing and/or additive metal coating. For example, a coating system or additive manufacturing system uses wire preheating and voltage clamping as described above, but omits the laser. In some other examples, the cladding system uses wire preheating and omits both the clamp and the laser. In either case, the metal may not necessarily be bonded to the workpiece, but may be formed into a coating and/or laid on a substrate from which the metal may be subsequently removed.

In some examples, the cladding system uses resistive preheating to preheat the wire. And melting the preheated welding wire by using a TIG welding arc.

Some example cladding systems use a preheating system to perform a pilot preheating (e.g., where both ends in the torch are preheated before the wire contacts the workpiece) and a transfer preheating (e.g., where the ends closer to the workpiece are exposed once current begins to flow in the workpiece lead). The cladding system switches the preheating system between a pre-heat-conducting mode and a transfer preheating mode.

In some cases, preheating electrodes with extended reach lengths can be affected by instabilities caused by short circuit control responses in submerged arc welding and/or GMAW processes. A conventional short circuit control response is to increase the current to clear the detected short circuit. However, the increased current may overheat the extended projection to extremely high temperatures, resulting in a decrease in the stiffness and/or mechanical stability of the wire. As a result, when the welding system 100 attempts to achieve a stable arc length or contact tip to work distance, the portions of the wire that are hotter blow at a higher rate than normal and can introduce arc length variations or oscillations. Some examples address this instability by controlling the welding power supply 302a using a current controlled (e.g., constant current) mode during long short circuit events (e.g., short circuits lasting more than 5 ms). The current controlled mode does not include the shark fin response or high simulated inductance that is characteristic of the short clearing method. For example, the current controlled mode may use the same average current as the current used for the wire feed rate in the spray mode (e.g., high current) or use a fixed low current (e.g., 50A or less). The welding system 100 also initiates wire retract to clear the short. After the short circuit is cleared, the welding system 100 reverts the mode to voltage controlled (e.g., constant voltage) spray and/or pulse spray mode. In such an example, the wire drive motor has a high responsiveness (e.g., similar to a motor used in a Controlled Short Circuit (CSC) mode), but the duty cycle is reduced relative to the duty cycle used in the CSC mode. In such an example, the motor is not used to clear the short circuit as fast as the CSC mode.

Some examples increase the deposition rate of the weld while using spray patterns reduces the heat input to the workpiece. The welding system 100 switches between spray mode in the low wire speed mode and cold wire feed in the high wire speed mode. In this context, cold wire refers to unmelted welding wire, whether preheated or not. In some such examples, welding system 100 preheats wire electrode 114 and performs welding in a spray mode (e.g., voltage controlled and/or pulsed) and then reduces the current to a lower current level (e.g., 50A or less). After operating in the spray mode for a period of time, the welding system accelerates the wire feed rate (e.g., to a maximum motor feed rate) to feed the cold (e.g., unmelted) wire electrode 114 into the weld puddle. The input of cold wire both adds filler metal and cools the weld puddle. The use of preheated wire increases the deposit of wire into the weld puddle before the weld puddle cools too much to further melt the wire, but preheating of the wire may be omitted. The welding system 100 then retracts the welding wire while maintaining a lower welding current to restart the welding arc. When the arc is restarted, the welding system 100 returns to spray mode at a higher current and feeds the wire electrode 114 at a lower wire feed rate. In some examples, welding system 100 maintains a higher current when feeding cold wire into the weld puddle to increase build-up, but reduces the current (e.g., to 50A or less) before retracting the wire to reduce spatter during arc restart. In such an example, the wire drive motor has a high responsiveness (e.g., similar to a motor used in a Controlled Short Circuit (CSC) mode), but the duty cycle is reduced relative to the duty cycle used in the CSC mode. In such an example, the motor is not used to clear the short circuit as fast as the CSC mode.

In some cases, poor physical contact between the wire electrode 114 and the contact tip 318 may result in an arcing effect between the wire electrode 114 and the contact tip 318, which may damage the contact tip 318. The disclosed example includes a clamping diode (e.g., a zener diode) to clamp the output voltage of the preheat power supply 302b to be less than a threshold (e.g., less than 14V). The use of clamping diodes reduces or eliminates the possibility of arcing between the contact tips 308, 318 and the wire electrode 114. Additionally, the clamping diode reduces the likelihood of the main welding current creating an arcing effect in the first contact tip 318. When the physical contact between the wire electrode 114 and the first contact tip 318 is poor, the arc current may be conducted or redirected through the clamp and the second contact tip 308 to the wire electrode 114 to prevent tip burn back and extend the life of the first contact tip 318. The clamp diode is selected to have a current capacity (e.g., with a conduction time of several hundred nanoseconds) to conduct both the preheat current and the weld current. In some examples, the clamping diode is a silicon carbide rectifier diode.

In some examples, the second contact tip 318 serves as a sensor for detecting a condition of an arcing effect at the first contact tip 308 (e.g., without preheating the wire electrode 114). When these conditions are detected, which produce an arcing effect at the first contact tip 308, the welding system 100 clamps the tip-wire contact voltage as described above.

While the examples disclosed above include contact tips 308, 318 that are coaxially aligned, in other examples, the axes of the contact tips 308, 318 are offset (e.g., parallel but not aligned) and/or tilted (e.g., not parallel). In some other examples, a bent or bent wire support (e.g., ceramic) is disposed between the two contact ends 308, 318 to improve contact at the first contact end 308. In some other examples, the first contact tip 318 is provided with a spring-loaded contact to contact the wire electrode 114, thereby ensuring contact between the first contact tip 318 and the wire electrode 114.

FIG. 18 illustrates an example weld assembly 1800 that includes an enthalpy measurement circuit 1802. Enthalpy measurement circuit 1802 determines the enthalpy applied to workpiece 106. The enthalpy applied to the workpiece 106 by the power supplies 302a, 302b is the sum of the enthalpy introduced to the wire electrode 114 by the preheating power supply 302b and the enthalpy introduced by the welding power supply 302 a. The example measurement circuit 1802 may determine the enthalpy based on a measured arc voltage, a measured welding-type current, and/or a measured preheat current or voltage drop across the electrode portion. Electrode preheat circuit 1802 controls the preheat current based on the determined enthalpy and the target enthalpy to be applied to workpiece 106. For example, the electrode preheating circuit 1802 can reduce the preheating current provided by the preheating power supply 302b based on the welding power applied by the welding power supply 302a to maintain a constant enthalpy applied to the workpiece 106. The welding power supply 302a may provide variable power based on, for example, variations in contact tip-to-work distance and/or arc length.

In some examples, welding system 100 includes an extension sensing circuit that determines an electrode extension distance of wire electrode 114. The preheating power supply 302b controls the preheating current based on the electrode protrusion distance. The example reach sensing circuit includes a current sensor for measuring a welding current supplied by the welding power supply 302a, and determines an electrode reach based on a measurement of the welding-type current.

FIG. 19 illustrates an example embodiment in which a resistive pre-heat wire 1902 is provided to a workpiece 1904 and a separate arc source (such as a tungsten electrode 1906) is provided to melt the wire 1902 and/or the workpiece 1904. The wire 1902 is preheated using contact ends 1908 and 1910, which contact ends 1908 and 1910 are electrically coupled to a preheating power supply 1912. The example contact tips 1908, 1910 and the preheat power supply 1912 may be implemented as described with reference to any of the examples in fig. 3, 11, 12, 13, 17, and/or 18.

Tungsten electrode 1906 generates an arc 1914. The gas nozzle 1916 is disposed in the same torch as the tungsten electrode 1906 and provides a shielding gas 1918. The reciprocating wire feeder 1920 enables the wire 1902 to travel in both a forward and/or a backward direction. Reciprocating to preheat the wire 1902 increases the welding or cladding travel speed and produces grain refinement effects when certain reciprocating frequencies are used.

For welding, the example preheating power source 1912 preheats the wire 1902 via the contact tips 1908, 1910, and the tungsten electrode 1906 provides the additional heat required to melt the wire 1902 and/or a portion of the workpiece 1904 to the weld puddle 1922. The preheated wire 1902 melts after being submerged in the weld puddle 1922, is melted by the arc 1914, and/or both. Any of the example control processes described herein may be used to perform welding, brazing, cladding, case hardening, metal addition, and/or any other welding-type operation.

Fig. 20 illustrates an example embodiment of providing a resistively preheated wire 2002 to a workpiece 2004 and providing a separate arc source (such as one or more laser heads 2006) to melt the wire 2002. The example of FIG. 20 includes the contact tips 1908 and 1910 of FIG. 19, the preheat power supply 1912, and the reciprocating wire feeder 1920. The example contact tips 1908, 1910 and the preheat power supply 1912 may be implemented as described with reference to any of the examples in fig. 3, 11, 12, 13, 17, and/or 18.

Similar to the tungsten electrode 1906 of fig. 19, the laser head 2006 of fig. 20 provides sufficient power to melt the workpiece 2004 to create a weld puddle 1922 in which the preheated wire 2002 is embedded to melt the preheated wire 2002 for metal deposition. The use of the preheated wire 2002 involves applying less energy to the workpiece 2004 via the laser head 2006 than would be required if a cold wire were used. In some cases, the preheated wire 1902 melts after being embedded in the workpiece 1904 and/or the weld puddle 1922 without additional heat from the laser. In other cases, the laser adds more heat to the wire to be melted into the puddle 1922. The reduced laser power and heat helps reduce base metal dilution of the workpiece 1904 in the erosion resistant weld overlay. As a result, the examples of fig. 19 and/or 20 may achieve increased deposition rates compared to conventional cold wire bonding processes and may be less likely to burn through workpieces 1904, 2004.

In some examples, the welding system 100 reacts to a wire short event. The example welding system 100 immediately turns off the preheating power using feedback to prevent the soft preheated welding wire from being squeezed and causing a jam between the first contact tip 318 and the second contact tip 308. The welding system 100 provides fast detection using feedback such as from the wire feed motor (e.g., motor current, motor torque, etc.) and/or from another wire feed force sensor or other feed force sensor between the two end motor currents. Additionally or alternatively, the welding system 100 uses feedback such as the duration of a short circuit measurement (e.g., arc voltage) to detect a wire break event (e.g., caused by extinguishing an arc by contacting the wire electrode 114 to the workpiece 106). In response to detecting this event, the welding system 100 turns off or disables the preheat power supply to prevent the wire from leaving a stubble between the contact tips.

Additionally or alternatively, the welding system 100 may implement a controlled pre-heat response to detect a wire short event. FIG. 21 illustrates example wire preheat current and/or voltage command waveforms 2102-2112 for reducing or preventing soft preheated wire from being pinched and causing a blockage between first contact tip 318 and second contact tip 308. In fig. 21, welding voltage feedback 2114 (represented by a waveform) is sensed by the welding system 100.

At a first time 2116, a wire break event occurs, resulting in a decrease in welding voltage feedback 2114. In the illustrated example, the control loop of the example system 100 does not immediately identify a stub event when the voltage drops. As a result, the example waveforms 2102 through 2108 do not respond to an initial drop at a first time 2116. In contrast, the example waveforms 2110, 2112 respond to the sensed voltage drop by decreasing the preheat command at a first rate.

At a second time 2118, the control loop in the welding system 100 recognizes that a wire break out event has occurred. In response to the control loop recognizing the wire kill event, the example waveforms 2102, 2104 are reduced to a reduced value, the waveforms 2106, 2108 begin to ramp down to a reduced value, and the waveforms 2110, 2122 reduce the preheat command at a second rate that is higher than the first rate.

At a third time 2120, the wire-out event is cleared and the welding voltage feedback 2114 is increased to the nominal value. In response to clearing the wire kill event, the waveforms 2102, 2106, 2110 increase substantially immediately to nominal values. Instead, the example waveforms 2104, 2108, 2122 ramp up to a nominal value.

Although example waveforms 2102-2112 are illustrated in fig. 21, any other waveform may be used, including, but not limited to, a combination of the individual components of waveforms 2102-2112. Example waveforms may include different slopes, which may be linear and/or non-linear.

Fig. 22 is a flow chart illustrating an example method 2200 of using resistive preheating to improve arc starting for welding. The method 2200 may be used with any of the example components 206, 1100, 1200, 1300, 1400, 1450, 1700, 1800 of fig. 2, 11, 12, 13, 14A, 14B, 17 or fig. 18.

The method 2200 begins at block 2202 in response to, for example, activating the welding system 100 or receiving a trigger signal requesting that the welding system 100 provide welding current to the wire electrode 114. At block 2204, the welding system 100 enables welding current to flow in the wire electrode 114 and to feed the wire 114.

At block 2206, the welding system 100 initiates a sequence steady state weld after beginning. At block 2208, the welding system welds with a predetermined preheat command target.

At block 2210, the welding system 100 determines (e.g., by measuring the temperature of the wire electrode 114 via the sensor) whether the preheat level of the wire electrode 114 is within a threshold deviation of a target preheat level (determined in block 2208). If the preheat level of the wire electrode 114 is within a threshold deviation of the target preheat level (block 2210), control returns to block 2208 to continue welding.

If the preheat level of the wire electrode 114 is not within a threshold deviation of the target preheat level (e.g., too cold or too hot) (block 2210), at block 2212 the welding system 110 adjusts the preheat current and returns control to block 2210 to check if the preheat level is within the threshold deviation of the target preheat level.

In some examples, the welding apparatus 110 includes or communicates with a user interface device to enable a user to adjust one or more preheating effects and/or parameters. Fig. 23 illustrates an example user interface device 2300 that can be used to implement a user interface of a welding apparatus. The example user interface 2300 may be implemented alone or as part of a larger welding user interface that allows other aspects of the welding device 110 to be controlled, such as voltage, current, and/or wire feed speed set points, among others.

The welding device 110 may use a default voltage command, a default current command, a default power command, and/or a default enthalpy command for the preheating power sources (e.g., power sources 302a, 302b) for the respective wire speeds, joint thicknesses, and/or joint geometries. However, such default commands may not always be the amount desired by the user for all cases. For example, the operator may wish to slightly alter the commands to control the amount of penetration and/or the amount of heat input, which in turn may reduce weld distortion. The example user interface 2300 enables a user to fine tune the pre-heat portion of the welding conditions to meet a particular application.

The example user interface 2300 includes a warm-up adjustment device 2302 and one or more warm-up indicator devices 2304, 2306. In the example of fig. 23, the preheat adjustment device 2302 is a dial that allows a user (e.g., via any of the example components 206, 1100, 1200, 1300, 1400, 1450, 1700, 1800 of fig. 2, 11, 12, 13, 14A, 14B, 17, or 18) to increase and/or decrease a level of preheat performed by the welding apparatus 110.

The graphical pre-heat indicator 2304 graphically indicates to a user the pre-heat level 2308 selected via the pre-heat adjustment device 2302 relative to a default pre-heat level 2310 and relative to an allowable range of pre-heat levels. The graphical pre-heat indicator 2304 also includes an indicator indicating the effect of adjusting the pre-heat level on weld penetration and/or other effects. For example, the graphical pre-heat indicator 2304 indicates that as the pre-heat level increases, the weld penetration decreases, and conversely, as the pre-heat level decreases, the weld penetration increases. As illustrated in fig. 24A, 24B, and 24C, when the graphical pre-heat indicator 2304 is adjusted, the pre-heat level 2308 is graphically represented as moving left and right.

In the example of fig. 23, a digital pre-heat indicator 2306 indicates a digital representation of the effect of changing the pre-heat level 2308 on the weld via a pre-heat adjustment apparatus 2302. For example, the digital pre-heat indicator 2306 displays the average heat input into the weld based on the pre-heat level 2308. 24A, 24B, and 24C illustrate example average heat inputs for different preheating levels. Other example digital representations include voltage command, preheat current, total energy and/or efficiency of the system.

Fig. 25 illustrates an example welding assembly 2500 using a weld control circuit 2504 that includes a user interface 2502 and implements a preheat control loop 2506. FIG. 26 is a block diagram of an example embodiment of a warm-up control loop 2506. The user interface 2502 includes the user interface 2300 of fig. 23 or another interface to enable a user of the welding assembly 2500 to adjust the preheating level. The weld control circuitry 2504 receives the preheat level selected via the user interface 2502 and controls the power supply 302b to change the preheat level. The welding control circuitry 2504 may further control the power supply 302a to adjust one or more aspects of the welding power based on the selected pre-heat level to improve performance at the selected pre-heat level. Welding control circuitry 2504 may also implement electrode preheating control circuitry.

The example preheat control loop 2506 of fig. 26 automatically controls the preheat power 2602 to the welding process 2604 to maintain a constant penetration depth by using feedback from the penetration depth sensor 2606. An example penetration sensor uses welding current as a measure of weld penetration. The interruption of the pulsed voltage signal by metal vapor pressure may be an early indication of burn-through. The example preheat control loop 2506 uses the penetration sensor 2606 as closed-loop feedback (e.g., subtractive feedback from a desired penetration and/or preheat level 2608 input from the user interface 2502). The preheat control loop 2506 may improve poor penetration (e.g., partial penetration) and/or prevent burn-through by detecting penetration and then independently adjusting the penetration using preheat power without introducing process instability. Other example penetration sensors that may be used include welding arcs and infrared sensors outside the weld pool.

Returning to fig. 25, the example assembly 2500 further includes voltage sense leads 2508, 2510 to measure the voltage across the preheated portion of the wire electrode 114. The voltage sense leads 2508, 2510 may be coupled to the two contact tips 308, 318, the wire liner, the wire drive motor, a diffuser in the welding gun, and/or any other substantially electrically equivalent point, for example. The welding control circuitry 2504 controls the preheat power supply 302b using a preheat control loop 2512. The preheat control loop 2512 uses the voltage sensed via leads 2508, 2510 and the current output by the power supply 302b to maintain a commanded power input, current input, voltage input, enthalpy and/or impedance to the portion of the wire electrode 114. In the example of fig. 25, the preheat control loop 2512 uses the error between the commanded preheat voltage and the voltage sensed via sense leads 2508, 2510 to adjust the preheat current, preheat voltage, and/or preheat power.

In some examples, the weld control circuitry 2504 further receives weld voltage feedback from the workpiece 106 and determines a voltage drop between the workpiece 106 and one or both of the contact tips 308, 318. The welding control circuitry 2504 may use voltage feedback including the contact tips 308, 318 and the workpiece 106 to calculate the total heat input to the wire 114 and/or to the workpiece 106 by the power supplies 302a, 302b and/or to control the voltage and/or current output by the power supplies 302a, 302 b.

The current present in the pre-heat circuit path (e.g., the power supply 302b, the contact tips 308, 318, and the portion of the wire electrode 114 between the contact tips 308, 318), as well as the current in any other connected circuitry and/or conductors, produces a voltage drop based on the amount of current and the amount of resistance in the circuit (e.g., in the portion of the wire electrode 114) in which the voltage is being measured (e.g., via the voltage sense leads 2508, 2510). If current is present but no voltage is measured, a conventional voltage controlled process would increase the current command until the voltage error is zero (e.g., voltage error-voltage feedback) and the command is satisfied. During conventional voltage control, any loss of voltage feedback (e.g., due to disconnection of any of sense leads 2508, 2510, due to a short circuit of sense leads 2508, 2510, etc.) may cause the preheat current to increase high enough to melt or vaporize the portion of the wire electrode being preheated off. Such an event may result in the failure or damage of many of the welding gun components.

The example welding control circuit 2504 detects and mitigates loss of voltage feedback to the preheat control loop 2512 by reducing the current command to the preheat power supply 302b and/or turning off the output of the preheat power supply 302 b. For example, the weld control circuitry 2504 may monitor the voltage and current in the preheat portion of the wire electrode 114 to determine whether the voltage and current are greater than respective thresholds (e.g., based on an expected minimum voltage drop during preheat). If neither the threshold voltage nor the current is present, the welding control circuitry 2504 pauses or modifies the preheat control loop 2512 to reduce the current command (e.g., to zero or a predetermined safe level), causing the welding power supply 302a to turn off welding power, and/or causing the preheat power supply 302b to turn off preheat power. The weld control circuitry 2504 may also indicate to an operator (e.g., via a message displayed on a display device of the user interface 2502) that the sense lead connection has been lost (e.g., via the user interface 2502). The response to the preheat voltage feedback loss protects the torch and torch components (contact tip, gas nozzle, etc.) and reduces or prevents damage to the part being welded.

In some examples, the weld control circuitry 2504 synchronizes the welding-type current and the preheat current to reduce the net current (and thus the net amount of heat) at the contact tips 308, 318. For example, the welding-type current and the preheat current may be alternating currents, and the welding control circuit 2504 controls the preheat current and/or the welding-type current to be synchronized such that the corresponding polarities of the welding-type current and the preheat current result in a net current at the contact tip 318 being reduced or eliminated.

In some examples, the welding control circuitry 2512 allows the welding power supply 302a to continue providing welding power to the weld without preheating, but will weld at a higher welding current than when preheating is enabled. Depending on a number of factors, such as wire feed speed, material thickness, and/or travel speed, higher currents may result in excessive penetration and/or damage to the portion being welded. The welding control circuitry 2504 may monitor the current from the welding power supply 302a and compare to a current limit (e.g., a current greater than an expected average current). If the current limit is exceeded, the welding control circuitry 2504 turns off the welding power supply 302a to avoid excessive penetration and/or workpiece damage.

As described above, the user interface 2502 may output heat input to the workpiece 106 via welding (e.g., based on a preheating level selected via the user interface 2502). The example welding control circuit 2504 of fig. 25 calculates the heat input based on the preheat voltage, preheat current, preheat power, welding voltage, welding current, and/or welding power output by the power supplies 302a, 302 b. Due to heat losses between the location of the wire electrode 114 being preheated and the location of the arc in the assembly 2500, the example weld control circuit 2504 includes a loss factor in the heat input calculation. The example weld control circuitry 2504 also includes an efficiency factor in the calculation, where the efficiency factor compensates for inefficiencies in power delivery to the wire electrode 114 and/or the voltage, current, and/or power used to calculate the heat input. Weld control circuitry 2504 may calculate the heat input using the following example equation 1:

∫(αI_weld(t)*V_weld(t)) dt equation 1

In equation 1, α represents the efficiency and/or power loss in the welded portion. The user interface 2502 may display the heat input and/or the weld control circuitry 2504 may use the calculated heat input to control the preheat heat input and/or the weld heat input. The heat input may be used in conjunction with, for example, penetration sensing to determine which of the preheating and/or welding power should be increased and/or decreased to achieve the desired welding results.

As described above, the example system 100 may preheat a portion of the wire electrode 114 prior to welding to reduce the presence of hydrogen gas in the wire electrode 114. Fig. 27 is a block diagram of an example assembly 2700 for monitoring a hydrogen level in a wire electrode 114 and preheating a portion of the wire electrode 114 to reduce hydrogen prior to welding. The assembly 2700 includes a hydrogen sensor 2702 and a preheat controller 2704. The preheat controller 2704 receives the hydrogen measurement signal from the hydrogen sensor 2702 and adjusts preheat parameters (e.g., current, voltage, power, enthalpy, etc.) of the preheat power supply 302b and/or welding parameters of the welding power supply 302 a.

By preheating wire electrode 114 to a desired temperature based on the rate at which wire electrode 114 is fed outwardly from assembly 2700, assembly 2700 more readily reduces and/or eliminates excess hydrogen gas relative to the presence or allowable amount of hydrogen gas as compared to conventional methods of hydrogen gas reduction.

The preheat controller 2704 controls preheat parameters such as preheat power, current, voltage, and/or joule heating based on observed heating efficiency of one type of wire electrode to reduce humidity in that type of wire electrode and based on the feed rate of the wire electrode 114. For example, a higher feed rate of the wire electrode 114 may require a higher preheat power. Welding the tubular electrode over the butt joint may require less preheating power than a tubular electrode having a joggle joint. Larger diameter tubular welding wires with larger cross-sectional areas may require higher preheat power. The example preheat controller 2704 may use a lookup table or other memory structure to retrieve preheat parameters based on the type of tubular welding wire and the wire feed rate input to the preheat controller 2704 (e.g., via a user interface) or another input method. In such an example, the warm-up controller 2704 may operate without the hydrogen sensor 2702 and rely on predetermined warm-up parameters.

The hydrogen sensor 2702 monitors the level of hydrogen on and/or near the wire electrode 114. For example, hydrogen sensor 2702 can be a palladium (Pd) -based sensor, such as a palladium-functionalized Carbon Nanotube (CNT). Another example embodiment of hydrogen sensor 2702 is a diode-based schottky sensor with a Pd alloy gate. Additionally or alternatively, highly ordered vertically oriented titanium dioxide (TiO)₂) A nanotube micro-electromechanical system (MEMS) sensor may be incorporated into the welding torch to detect low levels of hydrogen gas (e.g., parts per million, parts per billion, etc.) in or near the wire electrode 114. The preheat controller 2704 performs closed loop control of the preheat power supply 302b based on hydrogen measurements received from the hydrogen sensor 2702. The hydrogen sensor 2702 may also be placed near the preheat chamber as a measure of the hydrogen level prior to depositing the wire electrode 114 into the weld pool at the workpiece 106 to form the weld metal. A humidity sensor may be used instead of or in addition to the hydrogen sensor 2702.

The example assembly 2700 allows for the production of tubular electrodes at low cost and still achieve low hydrogen performance. The assembly 2700 may also reduce the cost of reducing or preventing hydrogen absorption during production of the wire electrode 114, such as costs associated with strip quality, tensile lubricants, flux sources and storage, and/or other production, storage, and/or procurement costs to a minimum. Additionally, packaging and/or storage costs may be reduced against moisture absorption in the wire electrode 114, and the shelf life of the wire electrode 114 may be extended.

Because hydrogen gas reduction is improved, manufacturers may select a greater variety of tubular welding wires for certain mechanical properties, including immunity to hydrogen provided by example components that provide wire preheating at the welding gun. The reduction of hydrogen gas becomes easier because it does not depend on the protrusion length like the conventional art. End users are generally unable to adjust the stick out length in a consistent manner, and therefore performing hydrogen reduction via preheating allows for a fixed, self-adjusting preheat length so that wire heating will be consistent and independent of stick out length. The shorter extension also improves the CTWD and improves the response of the welding power supply 302a to short circuit and/or burnout events. The pre-heating hydrogen reduction method further eliminates the need to pre-heat wire electrode 114 for an extended period of time before using wire 114. The pre-heating hydrogen reduction process may heat the wire electrode 114, which is more likely to heat the wire electrode than using the conventional extension process, further reducing the hydrogen level prior to entering the weld as compared to conventional processes.

In some examples, the weld-type electrode is a tubular electrode, and hydrogen gas that may diffuse into the electrode is substantially burned off by preheating the electrode to prevent at least a portion of the hydrogen gas from being introduced into the weld metal. Thus, the examples reduce the tendency for hydrogen induced cracking, stress corrosion cracking, and hydrogen embrittlement in the resulting weld.

Fig. 28 is a block diagram of an example embodiment of the power supplies 302a, 302B of fig. 2, 11, 12, 13, 14A, 14B, 17, 18, 25 and/or 27. The example power supplies 302a, 302b supply power to, control, and supply consumables to the welding application. In some examples, the power supplies 302a, 302b supply input power directly to the torch 108. In the illustrated example, the welding power supplies 302a, 302b are configured to provide power for welding operations and/or preheating operations. The example welding power supplies 302a, 302b also supply power to the wire feeder to supply the electrode wire 114 to the welding gun 108 for various welding applications (e.g., GMAW welding, Flux Core Arc Welding (FCAW)).

The power supplies 302a, 302b receive main power 2808 (e.g., from an AC power grid, an engine/generator set, a battery or other energy generating or storage device, or a combination thereof), condition the main power, and provide output power to one or more welding devices and/or preheating devices according to the needs of the system. The main power 2808 may be supplied from an offsite location (e.g., the main power may originate from a power grid). The welding power supplies 302a, 302b include a power converter 2810, the power converter 2810 may include a transformer, rectifier, switch, etc., capable of converting AC input power to AC and/or DC output power, as dictated by the requirements of the system (e.g., the particular welding process and recipe). The power converter 2810 converts input power (e.g., the main power 2808) to welding-type power based on a welding voltage set point and outputs the welding-type power via a welding circuit.

In some examples, the power converter 2810 is configured to convert the main power 2808 into both a welding-type power output and an auxiliary power output. However, in other examples, the power converter 2810 is adapted to convert only main power to welding power output, and a separate auxiliary converter is provided to convert the main power to auxiliary power. In some other examples, the power supplies 302a, 302b receive the converted auxiliary power output directly from the wall outlet. The power supplies 302a, 302b may employ any suitable power conversion system or mechanism to generate and supply both welding power and auxiliary power.

The power supplies 302a, 302b include a controller 2812 to control the operation of the power supplies 302a, 302 b. The welding power supplies 302a, 302b also include a user interface 2814. The controller 2812 receives input from a user interface 2814 through which a user may select a process and/or input desired parameters (e.g., voltage, current, a particular pulsed or non-pulsed welding regime, etc.). The user interface 2814 may receive input using any input device, such as via a keypad, keyboard, buttons, touch screen, voice-activated system, wireless device, or the like. In addition, the controller 2812 controls the operating parameters based on user input as well as based on other current operating parameters. In particular, the user interface 2814 may include a display 2816 for presenting, showing, or indicating information to an operator. The controller 2812 may also include interface circuitry for communicating data to other devices in the system, such as a wire feeder. For example, in some cases, the power supplies 302a, 302b communicate wirelessly with other welding devices within the welding system. Additionally, in some cases, the power sources 302a, 302b communicate with other welding devices using a wired connection, such as by using a Network Interface Controller (NIC) to transmit data over a network (e.g., ethernet, 10base t, 10base100, etc.). In the example of fig. 1, the controller 2812 communicates with the wire feeder via the welding circuit via a communication transceiver 2818.

The controller 2812 includes at least one controller or processor 2820 that controls the operation of the welding power supply 2802. The controller 2812 receives and processes a number of inputs associated with the performance and requirements of the system. Processor 2820 may include one or more microprocessors, such as one or more "general-purpose" microprocessors, one or more special-purpose microprocessors and/or ASICs, and/or any other type of processing device. For example, processor 2820 may include one or more Digital Signal Processors (DSPs).

The example controller 2812 includes one or more storage devices 2823 and one or more memory devices 2824. Storage 2823 (e.g., non-volatile memory) may include ROM, flash memory, a hard drive, and/or any other suitable optical, magnetic, and/or solid-state storage media, and/or combinations thereof. The storage 2823 stores data (e.g., data corresponding to a welding application), instructions (e.g., software or firmware that performs a welding process), and/or any other suitable data. Examples of stored data for welding applications include the pose (e.g., orientation) of the welding gun, the distance between the contact tip and the workpiece, voltage, current, welding device settings, and so forth.

The memory device 2824 may include volatile memory, such as Random Access Memory (RAM), and/or non-volatile memory, such as Read Only Memory (ROM). Memory device 2824 and/or storage device 2823 may store various information and may be used for various purposes. For example, memory device 2824 and/or storage device 2823 may store processor-executable instructions 2825 (e.g., firmware or software) for execution by processor 2820. Additionally, one or more control schemes for various welding processes and related settings and parameters may be stored in the storage device 2823 and/or the memory device 2824 along with code configured to provide a particular output during operation (e.g., initiate wire feed, enable gas flow, capture welding current data, detect short circuit parameters, determine an amount of spatter).

In some examples, welding power flows from the power converter 2810 through the weld cable 2826. The example weld cable 2826 may be attached and disconnected from the weld studs at each of the welding power supplies 302a, 302b (e.g., such that the weld cable 2826 can be easily replaced in the event of wear or damage). Additionally, in some examples, the welding data is provided over the weld cable 2826 such that the welding power and the welding data are provided and transmitted together over the weld cable 2826. The communication transceiver 2818 is communicatively coupled to the weld cable 2826 to communicate (e.g., transmit/receive) data over the weld cable 2826. The communication transceiver 2818 may be implemented based on various types of powerline communication methods and techniques. For example, the communication transceiver 2818 may provide data communication via the weld cable 2826 using IEEE standard P1901.2. In this manner, the welding cable 2826 may be used to provide welding power from the welding power supplies 302a, 302b to the wire feeder and the welding gun 108. Additionally or alternatively, the weld cable 2826 may be used to transmit and/or receive data communications to and/or from the wire feeder and the welding gun 108. The communication transceiver 2818 is communicatively coupled to the weld cable 2826, e.g., via a cable data coupler 2827, to characterize the weld cable 2826, as described in more detail below. The cable data coupler 2827 may be, for example, a voltage or current sensor.

In some examples, the power supplies 302a, 302b include or are implemented in wire feeders.

The example communications transceiver 2818 includes a receiver circuit 2821 and a transmitter circuit 2822. Typically, the receiver circuit 2821 receives data transmitted by the wire feeder via the weld cable 2826, and the transmitter circuit 2822 transmits data to the wire feeder via the weld cable 2826. As described in more detail below, the communication transceiver 2818 may enable remote configuration of the power supplies 302a, 302b from a location remote from the wire feeder and/or compensation of the welding voltage of the power supplies 302a, 302b using welding voltage feedback information transmitted by the wire feeder 104. In some examples, the receiver circuit 2821 receives communications via the welding circuit while the welding current is flowing through the welding circuit (e.g., during a welding-type operation) and/or after the welding current stops flowing through the welder (e.g., after the welding-type operation). Examples of such communications include welding voltage feedback information measured at a device (e.g., wire feeder) remote from the power supplies 302a, 302b as welding current flows through the welding circuit.

An example embodiment of a communications transceiver 2818 is described in U.S. patent No. 9,012,807. The entire contents of U.S. patent No. 9,012,807 are incorporated herein by reference. However, other implementations of the communication transceiver 2818 may be used.

The example wire feeder 104 also includes a communication transceiver 2819, which may be similar or identical in construction and/or function to communication transceiver 2818.

In some examples, the gas supply 2828 provides a shielding gas, such as argon, helium, carbon dioxide, and the like, depending on the welding application. The shielding gas flows to a valve 2830 that controls the gas flow and, if desired, can be selected to allow the amount of gas supplied to the welding application to be adjusted or regulated. The valve 2830 may be opened, closed, or otherwise operated by the controller 2812 to enable, disable, or control gas flow (e.g., shielding gas) through the valve 2830. The shielding gas exits valve 2830 and flows through cable 2832 (which may be housed with the welding power output in some embodiments) to a wire feeder that provides the shielding gas to the welding application. In some examples, the welding systems 302a, 302b do not include the gas supply 2828, the valve 2830, and/or the cable 2832.

While the method and/or system of the present invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the method and/or system. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. For example, the systems, blocks, and/or other components of the disclosed examples may be combined, divided, rearranged, and/or otherwise modified. Thus, the present methods and/or systems are not limited to the specific embodiments disclosed. On the contrary, the present method and/or system is intended to cover all embodiments falling within the scope of the appended claims, whether literally or under the doctrine of equivalents.

All references cited herein (including journal articles or abstracts, published or corresponding U.S. or foreign patent applications, issued U.S. or foreign patents, or any other references) are hereby incorporated by reference in their entirety, including all data, tables, figures, and text presented in the cited references.