Patent Application
20230158596
The disclosed technology generally relates to welding technologies and more particularly to electrode assemblies for arc welding, e.g., submerged arc welding.
Various welding technologies utilize welding wires that serves as a source of metal. For example, in metal arc welding, an electric arc is created when a voltage is applied between a consumable weld electrode wire, which serves as one electrode that advances towards a workpiece, and the workpiece, which serves as another electrode. The arc melts a tip of the metal wire, thereby producing droplets of the molten metal wire that deposit onto the workpiece to form a weldment or weld bead.
Technological and economic demands on welding technologies continue to grow in complexity. For example, the need for higher bead quality in both appearance and in mechanical properties continues to grow, including high yield strength, ductility and fracture toughness. Simultaneously, the higher bead quality is often demanded while maintaining economic feasibility. Some welding technologies aim to address these competing demands by improving the consumables, e.g. by improving the physical designs and/or compositions of the electrode wires.
Submerged arc welding (SAW) can provide highly economic solutions for some applications. The high deposition rates attained with submerged arc are chiefly responsible for the economies achieved with the process.
In an aspect, an electrode assembly for submerged arc welding (SAW) comprises a head portion and an extension portion arranged serially and configured to feed a consumable electrode therethrough, wherein during welding, the head portion is disposed to be distal to an arcing tip of the consumable electrode and the extension portion is disposed to be proximal to the arcing tip of the consumable electrode. The extension portion is elongated in a wire feed direction and is configured to electrically insulate the consumable electrode from a work piece during welding with an insulating sleeve surrounding the consumable electrode. The electrode assembly is configured such that, during SAW with consumable electrode inserted therethrough, a ratio between an electrical stick-out distance, which is measured between a contact tip portion disposed at an end of the head portion and the arcing tip of the consumable electrode, and a diameter of the electrode exceeds 30.
In another aspect, an electrode assembly for submerged arc welding, comprises a head portion and an extension portion arranged serially with the head portion, wherein the head portion and the extension portion are configured to feed a consumable electrode therethrough. The extension portion is configured to be disposed closer to an arcing tip of the consumable electrode relative to the head portion and comprises an envelope formed of a nonmagnetic material and an insulating sleeve disposed within the envelope and comprising a solid insulating material configured to surround the consumable electrode.
In another aspect, an extension portion configured for a submerged arc welding electrode assembly comprises an envelope formed of a nonmagnetic material and an insulating sleeve disposed within the envelope and comprising a solid insulating material configured to surround a consumable electrode. The extension portion is configured to be arranged serially with a head portion of the electrode assembly and to receive a consumable electrode from the head portion.
In processes using a consumable electrode, the electrode or the wire melts to provide an additive metal that fills a gap to form a weld joint that joins two metal workpieces. The welding processes using consumable electrodes include shielded metal arc welding (SMAW), gas metal arc welding (GMAW) or metal inert gas (MIG) welding, flux-cored arc welding (FCAW), metal-cored arc welding (MCAW), and submerged arc welding (SAW), among others.
The distinguishing feature of SAW is the flux 114, which covers the weld area and prevents arc radiation, sparks, spatter and fumes from escaping. The flux 114 allows for achieving high deposition rates and high quality weld deposit characteristics. In addition to shielding the arc 116 from view, the flux 114 provides a slag 118 which protects the weld metal 120 as it cools, deoxidizes and refines the weld metal 120, insulates the weld to reduce the cooling rate and helps shape the weld contour.
During the SAW process, the heat of the arc 116 melts some of the flux 114 along with the tip 106 of the electrode 104 to form a weld pool 122, as illustrated in
The power supply 108 generates a voltage and current for the system 100 and the voltage and current are applied to the workpiece 102 and the electrode 104. The current is applied to the electrode via the contact tip 110. High currents can be used in submerged arc welding and extremely high heat can be generated. Because the current is applied to the electrode 104 a short distance above its tip 106, relatively high amperages can be used on small diameter electrodes. This results in extremely high current densities on relatively small cross sections of electrode. Currents as high as or exceeding 600 amperes can be carried on electrodes as small as 64″, giving a density in the order of 100,000 amperes per square inch six to ten times that carried on stick electrodes.
Because of the high current density, the melt off rate is much higher for a given electrode diameter than with stick-electrode welding. The melt-off rate is affected by the electrode material, the flux 114, type of current, polarity, and length of wire beyond the point of electrical contact in the gun or head.
Submerged arc welding may be performed with either DC or AC power. Direct current gives better control of bead shape, penetration, and welding speed, and starting is relatively easier. Bead shape is usually best with DC electrode positive (DCEP or reverse polarity), which also provides maximum penetration. Highest deposition rates and minimum penetration can be obtained with DC electrode negative (DCEN). Alternating current minimizes arc blow and gives penetration between that of DCEP and DCEN.
The insulating blanket of flux 114 above the arc 116 prevents rapid escape of heat and concentrates it in the welding zone. Not only are the electrode 104 and base metal of the workpiece 102 melted rapidly, but the fusion is deep into the base metal. The deep penetration allows the use of small welding grooves, thus minimizing the amount of filler metal per foot of joint and permitting fast welding speeds. Fast welding, in turn, minimizes the total heat input into the assembly and, thus minimizes problems of heat distortion. Even relatively thick joints can be welded in one pass by submerged arc welding.
Welds made under the protective layer of flux 114 have good ductility and impact resistance and uniformity in bead appearance. Mechanical properties at least equal to those of the base metal are consistently obtained. In single-pass welds, the fused base material is large compared to the amount of filler metal used. Thus, in such welds the base metal may greatly influence the chemical and mechanical properties of the weld. For this reason, it is sometimes unnecessary to use electrodes of the same composition as the base metal for welding many of the low-alloy steels. However, the chemical composition and properties of multipass welds are less affected by the base metal and depend to a greater extent on the composition of the electrode, the activity of the flux, and the welding conditions.
Through regulation of current, voltage, and travel speed, the operator can exercise close control over penetration to provide any depth ranging from deep and narrow with high-crown reinforcement, to wide, nearly flat beads with shallow penetration. Beads with deep penetration may contain on the order of 70% melted base metal, while shallow beads may contain as little as 10% base metal. In some instances, the deep-penetration properties of submerged arc welding can be used to eliminate or reduce the expense of edge preparation.
The flux serves several functions in submerged arc welding. These include covering the molten weld metal to protect it from the atmosphere and acting as a slag which refines the molten deposit by scavenging oxides and other non-metallic inclusions. Metallic additions to the flux can add to the alloy content of the deposit and deoxidize it.
There are four types of fluxes based on their method of manufacture; fused, bonded, agglomerated and mechanically mixed.
Fluxes are also identified as basic, acid, and neutral. Basic fluxes contain oxides of metals which dissociate easily while acidic fluxes contain oxides which dissociate to a small extent. A neutral flux does not add or subtract from the composition of the weld deposit. Fluxes having a ratio of CaO or MnO to SiO2 which is greater than one are considered basic, those near one are considered neutral, and those less than one are acidic.
With proper selection of equipment, submerged arc is widely applicable to the welding requirements of industry. It can be used with all types of joints, and permits welding a full range of carbon and low alloy steels, from 16-gage sheet to the thickest plate. It is also applicable to some high-alloy, heat-treated, and stainless steels, and is a favored process for rebuilding and hard surfacing. Any degree of mechanization can be used—from the hand-held semi-automatic gun to boom or track-carried and fixture held multiple welding heads.
The high quality of submerged arc welds, the high deposition rates, the deep penetration, the adaptability of the process to full mechanization, and the comfort characteristics (no glare, sparks, spatter, smoke, or excessive heat radiation) make it a preferred process in steel fabrication. It is used extensively in ship and barge building, railroad car building, pipe manufacture, and in fabricating structural beams, girders, and columns where long welds are required. Automatic submerged arc installations are also key features of the welding areas of plants turning out mass-produced assemblies joined with repetitive short welds.
Other factors than deposition rates enter into the lowering of welding costs. Continuous electrode feed from coils, ranging in weight from 60 to 1,000 pounds, contributes to a high operating factor. Where the deep-penetration characteristics of the process permit the elimination or reduction of joint preparation, expense is reduced. After the weld has been run, cleaning costs are minimized, because of the elimination of spatter by the protective flux.
When submerged-arc equipment is used properly, the weld beads are smooth and uniform, so that grinding or machining are rarely required. Since the rapid heat input of the process minimizes distortion, the costs for straightening finished assemblies are reduced, especially if a carefully planned welding sequence has been followed. Submerged arc welding, in fact, often allows the pre-machining of parts, further adding to fabrication cost savings.
Because of these and other advantages provided by SAW, there is a desire and need to further improve various aspects of SAW, including even higher productivity and weld quality. For example, as one of the technical advantages of SAW derives from preheating the consumable electrode, there is a desire and need to further improve the preheating arrangement through improved electrode assembly design.
The electrical stick-out 216 of the electrode wire 206 is preheated by Joule heating. If the electrical electrode extension 216 is not sufficiently long, the electrode wire 206 may not be sufficiently preheated. On the other hand, an increase of the length of the electrical stick-out 216 increases the electrical resistance of the circuit, which in turn increases the heating and hence the temperature of the tip 208 of the electrode 206, leading to increased melting and deposition rate. The length of the electrical stick-out 216 in turn controls the dimensions of the weld bead since the length of the filler wire extension affects the burn-off rate. Further, electrical electrode extension 216 exerts an influence on penetration through its effect on the welding current. As the length of the electrical electrode extension 216 is increased, the preheating of and the voltage drop across the electrode wire 206 increases. The greater voltage drop can result in the bead shape being more convex, which can be overcome by increasing the input voltage by 2-5 volts. The length of the electrical stick-out 216 distance can be approximately 3-10 times a diameter of the electrode 206 depending on the type of steel being welded, for traditional steel welding processes.
To further improve upon submerged arc welding (SAW) technology, a long stick-out (LSO) or extended stick-out technology developed by Lincoln Electric company may be employed. Long stick-out SAW refers to SAW processes in which the length of the wire that sticks out (“stick-out length”) of the electrode contact tip, or the contact-to-work distance (CTWD), is increased relative to conventional SAW processes, e.g., longer than about 25 mm. As used herein, LSO refers to an electrode configuration in which the electrical stick out exceeds about 10 times a diameter of the electrode 306A. The longer stick-out length allows for a greater length of the electrode to be preheated prior to melting at the electrode tip. The preheating allows for melt-off rate to increase as a result, as it is easier to melt a preheated electrode wire for a given current density. The LSO SAW process can provide significant improvement in productivity and can provide up to 100% increase in submerged arc welding deposition rates over traditional SAW processes. The LSO SAW process can reduce or eliminate arc striking problems by allowing complete tailoring of the arc start characteristics. The LSO SAW can also provide improved control over the input of energy into the weld, lower heat input (less distortion), flux/wire ratio reduction.
The increased length of the stick-out portions in LSO SAW systems also allows for the LSO systems to be used to easily fill grooves that conventional SAW systems are either incapable of filling or can only fill using extremely precise arrangements and high operator skill. Specifically, while conventional SAW systems can be used with wide and/or short grooves, conventional SAW systems typically cannot be easily used with deeper and/or narrower grooves.
According to various embodiments, the LSO SAW electrode assemblies are capable of achieving significantly higher deposition rates compared to conventional SAW electrode assemblies for the same current. During the welding process, current is transferred into the electrode by the contact tip at a specific amperage and voltage. As the current flows through the electrode toward the tip of the electrode, the voltage drops and the electrode heats up. At the tip of the electrode, the current arcs to the workpiece. For LSO SAW assemblies, the increased length of the electrode results in a higher fraction of the total voltage drop occurring within the electrode than in conventional SAW assemblies. In some embodiments, the LSO SAW assemblies can be configured such that the voltage drop between the contact tip and the tip of the consumable electrode is at least 5%, at least 10%, at least 15%, or at least 20% (or is a value in a range defined by any of these values) of a total voltage drop across the total CTWD. In other embodiments, the electrode assembly is configured such that the voltage drop between the contact tip and the tip of the consumable electrode represents at least 1/30 of the total voltage drop across the CTWD, 1/15 of the total voltage drop across the CTWD, 1/10 of the total voltage drop across the CTWD, 1/7 of the total voltage drop across the CTWD, ⅕ of the total voltage drop across the CTWD, or a value in a range defined by any of these values. For example, in a conventional SAW electrode assembly where the total voltage drop along the CTWD is 30V, only about 1V of that total voltage drop may occur within the consumable electrode while the rest (about 29V) may drop across the arc length. In contrast, for an LSO SAW system of the same total voltage drop of 30V, about 4V of may drop occurs across the CTWD while the rest (about 26V) may drop cross the arc length. The increased voltage drop through the longer electrode results in the electrode being heated to a higher temperature than the electrode in a conventional SAW configuration and, as a result, the deposition rate increases.
Experiments have shown that the deposition rate per current for LSO SAW assemblies can exceed 0.05 lbs./hr./A, 0.06 lbs./hr./A, 0.07 lbs./hr./A, 0.08 lbs./hr./A, or a value in range defined by any of these values during welding.
In LSO SAW systems, the consumable electrode (e.g., electrodes 306B, 406B) extends beyond the end of the head portion (e.g., head portions 304B, 404B) such that the arcing tip (e.g., tips 308B, 408B) is visible. As previously discussed, the portion of the electrode that extends beyond the contact tip portion is referred to as the electrical stick-out. In some embodiments, the electrical stick-out is measured based on the diameter of the electrode. The length of the electrical stick-out in SAW can depend on the type of steel being welded, e.g., whether the steel being welded is a low alloy steel containing less than about 8 wt. % of non-iron elements or a high alloy steel containing greater than about 8 wt. % of non-iron elements. In conventional SAW for welding low and mild steel, the electrical stick-out length can be approximately 7-10 times the diameter of the electrode. In conventional SAW for welding high alloy steel, the electrical stick-out length can be approximately 3-5 times the diameter of the electrode. For example, in embodiments where the diameter of the electrode is 5/32″, the visible stick-out length can be approximately 1-1.5 inches. In contrast, in LSO SAW according to various embodiments, a stick out-to-diameter ratio, or a ratio between an electrical stick-out distance, measured between a contact tip portion disposed at an end of the head portion and the arcing tip of the consumable electrode, and a diameter of the electrode exceeds 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 or has a value in a range defined by any of these values. For example, these ratios can be obtained by electrical stick-out distance exceeding 125 mm, 130 mm, 135 mm, 140 mm, 145 mm, 150 mm, 155 mm, 160 mm, 165 mm or a value in a range defined by any of these values, and a diameter of the electrode having any value between 2.5 mm and 5.0 mm. For instance, for an electrical stick-out length of 155 mm and an electrode diameter of 3.2 mm, the stick out-to-diameter ratio is about 48, whereas for an electrical stick-out length of 125 mm and an electrode diameter of 4.0 mm, the stick-out-to-diameter ratio is about 31.
While increased stick-out length can advantageously provide certain advantages, such as higher deposition rate, various problems can arise for stick-out lengths exceeding, e.g., 25 mm, when conventional electrode assemblies are used. For example, the heated wire can move out of alignment and wander in the welding groove as the stick-out distance increases. This can pose a problem especially in welding deep and narrow grooves that may be used to minimize time and cost of joining thick sections, as LSO welding electrode assemblies can be too bulky to reach the bottom of the groove. To address this and other challenges, some electrode assemblies include an extension portion that serves as an insulated guide for the electrode. The extension portion provides, among other things, electrical and thermal insulation as well as mechanical rigidity to the heated electrode. However, some extensions may not be suitable for some applications, e.g., for filling narrow and deep grooves such as a triangular or U-shaped groove having a depth exceeding 4 inches and having an angle of an apex that is 16 degrees or less. Some designs of the electrode assemblies that include extension portions may be insufficient with respect to one or more of: optimized vertical and lateral dimensions, thermal and electrical insulation, arc instability caused by magnetic materials and compact flux delivery. In contrast various embodiments of the electrode assembly for submerged arc welding described herein address these and other needs.
Long Stick-Out Electrode Assembly with Covered Insulating Extension Portion
Disclosed herein are various electrode assemblies for improved LSO SAW and method of manufacturing and using the same.
In the illustrated example, the serially arranged head portion 602 and extension portion 604 are arranged serially and do not have vertically overlapping portions. While in the illustrated configuration the head portion 602 and the extension portion 604 are physically separated and exposes the consumable electrode 606 therebetween, embodiments are not so limited. In other arrangements, the contact tip portion and the extension portion may contact each other. It will be appreciated that, in the illustrated embodiment, because of the serial arrangement of the head portion 602 and the extension portion 604, the contact tip 610 and the extension portion 604 are also serially arranged, such that no portion of the extension portion 604 overlaps the contact tip 610. Further, the outer surface of the extension portion 604 forms the outermost surface of the electrode assembly 600 adjacent the arcing tip of the exposed consumable electrode 606.
In some embodiments, the electrode assembly 600 also includes a flux delivery system 614. The flux delivery system 614 is configured to deposit flux onto the workpiece during the SAW process. Advantageously, the flux delivery system 614 is configured such that the flux delivery system 614 does not limit the dimensions of a groove of a workpiece the extension portion 604 is capable of being inserted into. In the illustrated embodiment, the flux delivery system 614 is fixedly attached to the extension portion 604 with the bracket 612. In other embodiments, however, the flux delivery system 614 can be fixedly attached to the extension portion 604 in some other way. In still other embodiments, the flux delivery system 614 may not be fixedly attached to the extension portion 604. Instead, in some embodiments, the flux delivery system 614 may be fixedly attached to some other portion of the electrode assembly 600 or may not be attached to any portion of the electrode assembly 600. Additionally, because the electrode assembly 600 is configured for SAW, embodiments of the electrode assembly 600 are configured to be used in SAW systems without the use of a shielding gas.
The extension portion 604 is configured to electrically insulate the consumable electrode 606 from a work piece during welding with an insulating sleeve formed of a solid insulating material, e.g., a ceramic material, surrounding the consumable electrode. In some implementations, the solid insulating material may be a composite or layered insulator, e.g., a composite or layered ceramic. During welding, the consumable welding electrode 606 is preheated in the insulated extension portion 604 by Joule heating, prior to being melted at the arcing tip 608 of the consumable electrode 606. In some embodiments, the electrode assembly 608 is configured to heat the consumable electrode within the extension portion to a temperature up to 600° C., up to 700° C., up to 800° C., up to 900° C., or to a temperature in a range defined by any of these values.
In various embodiments, the extension portion is configured to electrically insulate the consumable electrode from a work piece during welding while having an outer surface formed of a substantially non-magnetic material surrounding the consumable electrode.
In some embodiments, the extension portion 700 is fixedly attached to the head portion with a bracket (e.g., bracket 612 in
According to embodiments, the envelope or nozzle body 706 functions as an outer envelope for the extension portion 700 and can be formed of a non-magnetic material. When the envelope 706 is formed of a magnetic material, it can exert or modify the magnetic field in its vicinity, thereby degrading, modifying or blowing the arc plasma. Furthermore, a magnetic material can become magnetized or demagnetized over time, thereby resulting in a drift of the arc characteristics. To address these and other concerns, in some embodiments, the envelope 706 is formed of a non-magnetic material such as a non-magnetic steel. As described herein, a non-magnetic steel refers to a steel having a low ferrite content and a high austenitic content, e.g., a steel having a ferrite number (FN) less than about 8. For example, the non-magnetic steel can be a high Cr-content steel, such as a stainless steel. Forming the nozzle body 706 out of a non-magnetic material advantageously improves the consistency of the magnetic field around the consumable electrode and reduces arc instability and welding defects. The non-magnetic material also reduces any instability of the welding parameters that may be caused by magnetization of the extension portion 706 over time.
Furthermore, the insulating sleeve 708 allows the extension portion 700 to contact groove sidewalls of the workpiece without risking an electrical short between the electrode and the workpiece. When the electrode is heated to above-described temperatures during welding, the insulating material may lose some of its resistivity. To ensure that voltage drop caused by such contact remains relatively low, the solid insulating material is formed of an insulating material and configured to sustain a voltage difference of at least 5V, 10V, 15V, 20V, 25V or a value in range defined by any of these values, without substantially conducting when an outer surface of the extension portion 700 contacts the workpiece.
In some embodiments, the insulating sleeve 708 is formed from an insulating ceramic material. For example, in some embodiments, the insulating sleeve 708 is formed of alumina (Al2O3) or silicon carbide (SiC). In other embodiments, however, other insulating materials can be used. For example, in some embodiments, the insulating sleeve 708 comprises silicon nitride, magnesia-stabilized zirconia, yttria-stabilized zirconia, magnesium oxide, or a zirconia-toughened alumina. The ceramic insulating sleeve 708 can be manufactured using various methods such as powder pressing, cold isostatic pressing, hot pressing, injection molding and slip casting. Additionally, in some embodiments, the ceramic insulating sleeve 708 is not machined.
In various embodiments, the extension portion 700 is configured to electrically insulate the consumable electrode from a work piece and has a shape, length and a lateral dimension such that the length of the electrical stick-out between the contact tip portion (e.g., contact tip 610 shown in
In addition, the insulating sleeve 708 enables, among other things, the shape and width of the extension portion 700 to be optimized for inserting the extension portion 700 into narrow grooves as described herein. According to various embodiments, the maximum width of the extension portion 700 at upper, untampered portions thereof can be less than 20 mm, 18 mm, 16 mm, 14 mm, 12 mm, or a value in a range defined by any of these values. Additionally, in some embodiments, the extension portion 700 can have a generally cylindrical shape having at least a portion that tapers inward towards the second end 714B such that the width of the extension portion 700 at the second end 714B is less than a maximum width of the extension portion 700. In the illustrated configuration, the extension portion 700 is tapered at a lower portion thereof, while an upper portion of the extension portion 700 is substantially straight. However, embodiments are not so limited and in other configurations, the extension portion 700 can be tapered substantially throughout its entire length. For example, in some embodiments, the extension portion 700 can have a maximum width of 16 mm that tapers to a width of 10.8 mm at the second end 714B. In other embodiments, however, the tapered second end 714B can have a different width. For example, in some embodiments, the width of the extension portion 700 at the second end 714B can be 12 mm, 11 mm, 10 mm, 9 mm, 8 mm, less then 8 mm, or a value in a range defined by any of these values. In some embodiments, the extension portion 700 can taper inwards at the second end 714B at an angle of 2°, 3°, 4°, 5°, 6°, 7°, 8°, more than 8°, or a value in a range defined by any of these values. For illustrative purposes only, roughly one third of the length of the illustrated extension portion 700 is tapered. However, it will be appreciated that any suitable fraction of the length may be tapered, including substantially the entire length, e.g., greater than 20%, 40%, 60% or 80%, 100%, or a value in a range defined by any of these values. It will be further appreciated that the tapered sidewall may not be straight, but the degree of tapering may vary with length. For example, the degree of tapering may vary, e.g., continuously or discontinuously, throughout the tapered portion. As configured, the extension portion 700 can be configured to not touch the sidewalls of a narrow groove such as a generally triangular trench as described elsewhere in the application. Any portion of the tapered portion can be configured such that tangents of the exterior sidewalls form a triangle or a cone having an angle of an apex that is less than 16 degrees, 12 degrees, 10 degrees, 8 degrees, 6 degrees, or a value in a range defined by any of these values. Advantageously, the shape and dimensions of the extension portion 700 as described can enable its insertion into narrow grooves without contacting the sidewalls thereof. Additionally, as will be discussed in greater detail elsewhere in the application, the tapered second end 714B advantageously allows multiple electrode assemblies to be positioned more closely adjacent to each other when use din a multi-arc configuration.
Another benefit of the electrode assembly 700 is that flux-to-wire consumption ratio is lower than conventional SAW assemblies because the electrode deposition rate increases while the flux consumption remains constant.
As previously discussed, the insulating sleeve 708 is disposed within the envelope or nozzle body 706. In some embodiments, the insulating sleeve 708 is placed within the nozzle body 706 without an adhesive or other material such that any gaps that may exist between the inner surfaces of the nozzle body 706 and the outer surfaces of the insulating sleeve 708 are filled with air and the insulating sleeve 708 can move or rotate relative to the envelope or nozzle body 706. In other embodiments, however, the insulating sleeve 708 may be securely attached to the nozzle body 706 with an intervening material. For example, in some embodiments, the insulating sleeve 608 is disposed within the nozzle body 706 with a suitable sealant or adhesive. In these embodiments, the suitable sealant may be disposed between the nozzle body 606 and the insulating sleeve 708 such that the sealant fills any gap that may exist between the inner surfaces of the nozzle body 706 and the outer surfaces of the insulating sleeve such that the insulating nozzle 708 is immobilized with respect to the nozzle body 706. In these embodiments, the suitable sealant may be a relatively soft material and may serve as a shock absorbing layer between the insulating sleeve 708 and the nozzle body 706 such that cracking of the insulating sleeve 708 under mechanical or thermal stress is suppressed or prevented. In other embodiments, a different material can be used to securely attach the insulating sleeve 708 within the nozzle body 706. For example, in some embodiments, the insulating sleeve 708 and the envelope or nozzle body 706 may be attached using a brazed metallic joint. In other embodiments, the insulating sleeve 708 and the envelope or nozzle body 706 may be attached using a non-metallic sealant or adhesive such as a polymeric adhesive material or epoxy.
One additional advantage of utilizing the relatively narrow extension portion as described herein is that it facilitates using multiple electrode assemblies in multi-arc set-ups. When welding large pieces of metal together, it is sometimes desirable to use multiple electrode assemblies at the same time to further increase the filler metal deposition rate. During multi-arc welding, the tips of multiple electrodes should be positioned closely adjacent to each other such that each of the electrode tips is disposed within the same weld pool. However, it is often difficult to use conventional SAW electrode assemblies in a multi-arc set-up. This is because the large diameter of the head portions (e.g., head portions 204 (
With this configuration, the first and second electrode assemblies 902A, 902B can be positioned such that a distance 916 between the tips 910A, 910B of the electrodes 908A, 908B is sufficiently small to allow for efficient multi-arc welding. Specifically, the shape, length, and width of the extension portions 912A, 912B as described herein allows for the extension portions 912A, 912B to be simultaneously positioned within narrow and deep grooves such that the tips 910A, 910B are disposed within the same weld pool during the SAW process without the extension portions contacting the sidewalls of the grooves. For example, in some embodiments, the first and second electrode assemblies 902A, 902B can be positioned such that, during welding, the distance 916 between the tips 910A, 910B is 15 mm while the angle 920 between the electrode assemblies 902A, 902B is 20 degrees. However, this is only one example. In other embodiments, the electrode assemblies 902A, 902B can be positioned such that, during multi-arc welding operations, the distance 916 between the tips 910A, 910B is less than 30 mm, 25 mm, 20 mm, 15 mm, or a value in a range defined by any one of these values, and the electrode assemblies 902A, 902B are oriented such that the angle 920 between the electrode assemblies 902A, 902B is less than 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees, 15 degrees, 10 degrees, 5 degrees, or a value in a range defined by any one of these values.
Still referring to
1. An electrode assembly for submerged arc welding, comprising:
2. An electrode assembly for submerged arc welding, comprising:
3. An electrode assembly for submerged arc welding, comprising:
4. An electrode assembly for submerged arc welding, comprising:
5. An electrode assembly for submerged arc welding, comprising:
6. An electrode assembly for submerged arc welding, comprising:
7. An electrode assembly for submerged arc welding, comprising:
8. An electrode assembly for submerged arc welding, comprising:
9. An electrode assembly for submerged arc welding, comprising:
10. An electrode assembly for submerged arc welding, comprising:
11. An electrode assembly for submerged arc welding, comprising:
12. An electrode assembly for submerged arc welding, comprising:
13. The electrode assembly according to any of the above examples, wherein the solid insulating material comprises a ceramic material.
14. The electrode assembly according to any of the above examples, wherein the solid insulating material comprises an insulating sleeve configured to pass the consumable electrode therethrough.
15. The electrode assembly of any one of the above examples, wherein the extension portion is formed of a material selected from the group consisting of silicon nitride, magnesia-stabilized zirconia, yttria-stabilized zirconia, silicon carbide, magnesium oxide, alumina or a zirconia-toughened alumina.
16. The electrode assembly of any one of the above examples, wherein the extension portion is configured to electrically insulate the consumable electrode from a work piece and has a shape, length and a lateral dimension such that the extension portion is configured to be capable of not contacting a sidewall of a triangular trench having a depth exceeding 4 inches and having an angle of an apex that is less than 16 degrees while the tip of the consumable electrode contacts the apex.
17. The electrode assembly of any one of the above examples, wherein the extension portion is configured to electrically insulate the consumable electrode from a work piece during welding while having an outer surface formed of a substantially non-magnetic material surrounding the consumable electrode.
18. The electrode assembly of any one of the above examples, wherein the extension portion is configured to electrically insulate the consumable electrode from a work piece and has a shape, length and a lateral dimension such that a contact tip-to-work distance (CTWD) between the contact tip portion and the tip of the consumable electrode during welding exceeds 125 mm.
19. The electrode assembly of any one of the above examples, further comprising a flux delivery system fixedly attached to the extension portion and configured such that the flux delivery system does not limit dimensions of a groove of a workpiece the extension portion is capable of being inserted into.
20. The electrode assembly of any one of the above examples, wherein the extension portion is configured to electrically insulate the consumable electrode from a work piece and has a shape, length and a lateral dimension such that the electrode assembly is configured to achieve a deposition rate per current exceeding 0.05 lbs./hr./A during welding.
21. The electrode assembly of any one of the above examples, wherein the extension portion is configured to electrically insulate the consumable electrode from a work piece and has a shape, length and a lateral dimension such that the electrode assembly is configured to achieve a deposition rate exceeding 35 lbs./hr. at a current less than 900 A during welding.
22. The electrode assembly of any one of the above examples, wherein the extension portion is configured to electrically insulate the consumable electrode from a work piece and has a shape, length and a lateral dimension such that the consumable electrode drops at least 5% of a total voltage drop cross a contact-to-work distance (CTWD) between the contact tip portion and the tip of the consumable electrode.
23. The electrode assembly of any one of the above examples, wherein the extension portion is configured to electrically insulate the consumable electrode from a work piece and has a shape, length and a lateral dimension such that a stick-out portion of the consumable electrode drops at least 2V of a total voltage drop cross a contact-to-work distance (CTWD) between the contact tip portion and the tip of the consumable electrode.
24. The electrode assembly of any one of the above examples, wherein the extension portion is configured to electrically insulate the consumable electrode from a work piece and has a shape, length and a lateral dimension such that the electrode assembly is configured to heat the consumable electrode by Joule heating within the extension portion to a temperature up to 800° C.
25. The electrode assembly of any one of the above examples, wherein the extension portion is configured to electrically insulate the consumable electrode from a work piece during welding with a solid insulating sleeve, wherein the solid insulating sleeve has sufficient resistance such that it is configured to sustain a voltage difference of at least 5V without substantially conducting when an outer surface of the extension portion contacts the work piece.
26. An electrode assembly for submerged arc welding (SAW), comprising:
27. The electrode assembly of example 26, wherein the extension portion has an outer surface formed of a substantially non-magnetic material surrounding the insulating sleeve.
28. The electrode assembly of example 27, wherein the insulating sleeve is formed of a ceramic material that is enveloped by a substantially non-magnetic steel-based envelope forming the outer surface of the extension portion.
29. The electrode assembly of example 28, wherein the insulating sleeve and the non-magnetic steel-based envelope are held together by an adhesive layer.
30. The electrode assembly of example 29, wherein the adhesive layer comprises a brazed joint comprising a metallic filler material.
31. The electrode assembly of example 26, wherein the extension portion has a length greater than 100 mm.
32. The electrode assembly of example 31 wherein the electrode assembly is configured for the electrical stick-out distance exceeding 125 mm.
33. The electrode assembly of example 32, wherein the electrode assembly is configured for the diameter of the electrode exceeding 3 mm.
34. The electrode assembly of example 32, wherein the extension portion has an elongated shape such that, when fully inserted into a triangular trench having a depth exceeding 4 inches and having an angle of an apex that is less than 16 degrees such that the tip of the consumable electrode contacts the apex of the triangular trench, no part of the extension portion contacts a sidewall of the triangular trench.
35. The electrode assembly of example 32, wherein the electrode assembly is configured to achieve a deposition rate per current exceeding 0.05 lbs./hr./A during welding.
36. The electrode assembly of example 32, wherein the electrode assembly is configured to achieve a deposition rate exceeding 35 lbs./hr. at a current less than 900 A during welding.
37. The electrode assembly of example 32, wherein the electrode assembly is configured to drop at least 5% of a total voltage drop across a distance between the head portion and the arcing tip of the consumable electrode.
38. The electrode assembly of example 32, wherein the electrode assembly is configured to heat the consumable electrode by Joule heating within the extension portion to a temperature up to 800° C.
39. The electrode assembly of example 26, wherein the insulating sleeve has sufficient resistance such that it is configured to sustain a voltage difference of at least 5V without substantially conducting when an outer surface of the extension portion contacts the work piece.
40. The electrode assembly of example 39 wherein the insulating sleeve is formed of a ceramic material selected from the group consisting of silicon nitride, magnesia-stabilized zirconia, yttria-stabilized zirconia, silicon carbide, magnesium oxide, alumina, or a zirconia-toughened alumina.
41. The electrode assembly of example 26, further comprising:
42. An electrode assembly for submerged arc welding, comprising:
43. The electrode assembly of example 42 wherein:
44. The electrode assembly of example 43 wherein the electrode assembly is configured for an electrical stick-out distance, measured between a contact tip portion disposed at an end of the head portion and the arcing tip of the consumable electrode, exceeding 125 mm.
45. The electrode assembly of example 44, wherein the electrode assembly configured such that a ratio between an electrical stick-out distance, measured between a contact tip portion disposed at an end of the head portion and the arcing tip of the consumable electrode, and a diameter of the electrode exceeds 30.
46. The electrode assembly of example 42 wherein the solid insulating material comprises a ceramic material.
47. The electrode assembly of example 42 wherein the insulating sleeve is fixedly attached to the envelope by an adhesive layer.
48. The electrode assembly of example 47 wherein adhesive layer comprises a brazed metallic joint.
49. An extension portion configured for a submerged arc welding electrode assembly, the extension portion comprising:
50. The extension portion of example 49, wherein the extension portion has a length greater than 100 mm.
51. The extension portion of example 49, wherein the extension portion is configured for a diameter of the consumable electrode exceeding 3 mm.
52. The extension portion of example 51, wherein the extension portion is configured such that during welding with the consumable electrode inserted therethrough, a ratio between an electrical stick-out distance, measured between a contact tip portion disposed at an end of the head portion and an arcing tip of the consumable electrode, and the diameter of the electrode exceeds 30.
53. The extension portion of example 49, wherein the insulating sleeve is formed of a ceramic material.
54. The extension portion of example 49, wherein the envelope is formed of a substantially non-magnetic steel-based material.
55. The extension portion of example 54, wherein the envelope is formed of a stainless steel.
56. The extension portion of example 49, wherein the insulating sleeve and the envelope are held together by an adhesive layer.
57. The extension portion of example 56, wherein the adhesive layer comprises a brazed joint comprising a metallic filler material.
58. A method of welding a workpiece, comprising:
59. The method of example 58 wherein the extension portion has a length greater than 100 mm
60. The method of example 58 wherein:
61. The method of example 60, further comprising:
62. The method of example 58 wherein the electrode assembly is configured to achieve a deposition rate per current exceeding 0.05 lbs./hr./A.
63. The method of example 58 wherein the electrode assembly is configured to achieve a deposition rate exceeding 35 lbs./hr. at a current less than 900 A.
64. The method of example 58 wherein the electrode assembly is configured to drop at least 5% of a total voltage drop across a distance between the head portion and the arcing tip of the consumable electrode.
65. The method of example 58 wherein the electrode assembly is configured to heat the consumable electrode by Joule heating within the extension portion to a temperature up to 800° C. during welding.
66. A multi-arc welding system for submerged arc welding within a groove on a workpiece, wherein the groove has a depth exceeding 4 inches and an angle of an apex that is less than 16 degrees, the system comprising:
67. The system of example 66 wherein, during welding, the first and second electrode assemblies are configured to be positioned within the groove such that a distance between the tips of the first and second consumable electrodes is less than 30 mm and an angle between the first and second electrode assemblies is less than 40 degrees.
68. The system of example 66, further comprising:
69. The system of example 66, wherein:
70. The system of example 66 wherein the first and second extension portions each have a length greater than 100 mm.
Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” “include,” “including” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The word “coupled”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Likewise, the word “connected”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number, respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.
Moreover, conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” “for example,” “such as” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or whether these features, elements and/or states are included or are to be performed in any particular embodiment.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel apparatus, methods, and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. For example, while blocks are presented in a given arrangement, alternative embodiments may perform similar functionalities with different components and/or circuit topologies, and some blocks may be deleted, moved, added, subdivided, combined, and/or modified. Each of these blocks may be implemented in a variety of different ways. Any suitable combination of the elements and acts of the various embodiments described above can be combined to provide further embodiments. The various features and processes described above may be implemented independently of one another, or may be combined in various ways. All possible combinations and subcombinations of features of this disclosure are intended to fall within the scope of this disclosure.
Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. This application claims the benefit under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63/264,358, entitled ELECTRODE ASSEMBLY FOR ARC WELDING, filed Nov. 19, 2021, and to U.S. Provisional Patent Application No. 63/370,430, entitled ELECTRODE ASSEMBLY FOR ARC WELDING, filed Aug. 4, 2022. The entirety of each of the above applications is hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 63264358 | Nov 2021 | US | |
| 63370430 | Aug 2022 | US |
