MXPA97004675A - Apparatus for joining metal components using thin filling nozzle, amp - Google Patents

Abstract

A filler material guide nozzle assembly (12A-12J), for feeding molten metal filler wire (10) or other metal shapes in metal joints of high aspect ratio (ratio of depth to width), of reduced width (2) with control and stability of the position of the filler material as it enters the area of the casting vessel. The filler material guide nozzle assembly is designed with a thin but rigid non-circular cross-sectional shape, with its width dimension significantly greater than its thickness dimension, and can be used in welded joints of very small width or otherwise fused to provide the precision and stability required for reliable addition of the filler material. During use with welding, brazing and similar processes, the outlet end of the nozzle is located within the joint near the bottom, near the area to be melted. The width dimension of the nozzle apparatus is oriented parallel to the depth of the weld joint and, the thickness dimension is oriented perpendicular to the depth of the joint. The thickness of the nozzle apparatus is less than the thickness of the joint between the components to be fused with the filler metal, allowing the exit end of the nozzle to be adjusted within the joint and in close proximity to the casting vessel during the uni process

Description

APPARATUS FOR JOINING METAL COMPONENTS USING THICK, FILLED NOZZLE NOZZLE Field of the Invention This invention relates to automated welding of metal components. In particular, the invention relates to automated welding in a small width slot using a flat welding electrode.

BACKGROUND OF THE INVENTION Tension corrosion cracking (SCC) has led to the critical need for repair or replacement of many components and pipes in boiling water reactors around the world. Welding joints have historically been the most likely areas of failure due to SCC due to their typically high stress stress values and their high degree of thermal sensitization in the HAZ. One solution to this problem is to replace the components with new material that has improvements in chemical composition. Due to the excessively high cost of replacing some components, the replacement may be more durable. Replacements are generally an installation of newer SCC-resistant material attached to the older material susceptible to SCC, so it is highly desirable even for those cases where the bonding process increases the residual stress and microstructural conditions in the material. old, since the relatively lower thermal efficiency and the resulting effect of overheating, of the conventional joining practices has frequently been one of the direct causes of the failure of the old component. Therefore, there is a need for a mechanized welding process that will produce weld joints that have significantly improved resistance to SCC. This can be achieved by using joint designs with deep but very narrow slot widths to minimize the amount of heat placed within the welding material, thus minimizing residual stresses in the vicinity of the weld joint. Another benefit is an improvement in the SCC resistance of the microstructure of the heat affected zones (HAZ) adjacent to the weld. In addition, there is a need for a welding method that decreases welding time and, personal exposure to man-rem radiation and production costs, associated with the lowering of a "critical point" of a nuclear power plant. in operation. Conventional welding practices, which include those used for field work, have relatively low overall thermal efficiency since a large part of the heat is devoted to melting the required large volume of filler wire, rather than the melting of the walls. the union together. This condition is a direct result of the non-necessary welding points used. In contrast, the use of very narrow weld grooves improves productivity due to the superior thermal and volumetric efficiencies of this new method, which results primarily from the reduced heat input parameters and the reduced width joint design, respectively . One approach used in the welding industry to complete narrow slot joints on thicker material when the electrode and / or the filler wire projects beyond its support means becomes excessive is to make the welding torch assembly so thin as practical, to fit within the joint and to be able to get close to or to the bottom and then make the width of the joint as narrow as possible consistent with the reduced internal torch width. The use of this style of internal torch still results in a wide joint that must be resorted to by other techniques to cause the filler metal to combine the side walls alternately, such as lateral oscillation of electrode tip or lateral oscillation of magnetic arc or , the use of two or more passes per layer. The approach of thinning the torch to fit within the joint (and in some cases also thinning the display device) has the severe disadvantage of being limited in the amount of possible joint width reduction in accordance with the reduced side of the torch., which typically includes provisions for an electrode holder, a welding gas cup / nozzle, a wire feed guide nozzle (for non-consumable electrode processes), water cooling flow circuits as required and, in Occasionally, optical components of the visualization camera also when used with remotely applied processes. The total result is a joint width that is considerably greater than desired to obtain a minimum weld width and therefore minimum weld volume that can be adequately completed with a minimum heat input. Achieving these minimum values provides the residual stresses correspondingly lower, reduced the size and severity of the area affected by the heat and the lower deposition of the filler material. Conventional filler nozzles are subjected to undesirable deflections. These deflections can be elastic or plastic (permanent) and can occur from the wire with excessive "emptying" (helical form due to being wound on a circular reel) or from contact with the walls of the union, manual handling of the equipment welding or brazing, etc. The larger diameter circular cross-section nozzles commonly used, while they are strong enough to successfully resist unacceptable deflections, limit either the view within the weld joint or, they are too wide to easily fit inside. or be manipulated as required within very small weld joints or both. The view is typically limited by a large diameter nozzle since the viewing position is from above the nozzle and the viewing angle of the work surface is high (eg, 45 ° to 75 °), in order to maintain the preferred low wire entry angle (eg, 15 ° to 45 °). For weld joints with a lower aspect ratio (ratio of the depth of attachment to the width), the conventional circular type of wire guide can be positioned so that it does not extend into the joint, with only an unsupported length of Wire protruding from the nozzle inside the joint. For relatively short unsupported lengths of wire extending beyond the outlet end of a nozzle, this method can be satisfactory, although the requirement becomes more important than the unsupported length of wire that is straight. This requirement of verticality is difficult to achieve due to the inherent tendency to deform from a linear shape after being unwound from a reel of typically small diameter. However, for extremely thin joints with a higher aspect ratio, it is preferred that the wire guide extend close to the bottom of the wire so that the wire position is located more accurately and consistently with the wire. with respect to the objective position of the weld deposit and, with respect to the tip of the electrode (for non-consumable electrode processes).

Brief Description of the Invention The present invention is an apparatus for feeding molten filler metal wire or other metal shapes into welds of reduced width, high aspect ratio (ratio of depth to width) with control and stability of metal position. Conformant filler enters the melt container area The filler material guide nozzle assembly is designed with a thin, albeit rigid, non-circular cross-sectional shape, with its width dimension significantly greater than its thickness dimension and can be used in welded joints with reduced width or otherwise cast to provide the precision and stability required for reliable addition of filler material This type of nozzle can be applied in situations where the joint does not have enough width to otherwise accommodate a conventional circular cross-section nozzle ( round, tubular) of the resistance s sufficient to avoid the increased risk of undesirable bending deflections or, "-" to accommodate a thin welding torch assembly within the joint During use with welding, brazing and similar processes, the outlet end of the nozzle is located within the union near the bottom, near the area to be fused The width dimension of the nozzle apparatus is oriented parallel to the depth of the weld joint and, the thickness dimension is oriented perpendicular to the depth of The joint The thickness of the nozzle apparatus is less than the thickness of the joint between the components to be fused with the filler metal, allowing the outlet end of the nozzle to be adjusted within the joint and in close proximity to the container of melting during the bonding process. This nozzle apparatus is suitable for automated and mechanized welding or brazing processes of the electric arc type or energy beam, such as the tungsten arc process (GTA) or the laser beam process. Brazing differs from welding in that the related materials are not melted to any significant degree, since in brazing the filler metal melts at a substantially lower temperature than the related metals. In addition, the apparatus can be used beneficially for the deposition of wire which is a combined consumable electrode and a metal filler as in the metallic inert gas (MIG) process or, only a metal filler, such as in: "- Other forms of filling materials consumed continuously or previously placed, such as fluidized powder or paste, are also suitable for use with the apparatus In addition to filling materials such as flows and surfactants can be applied with the assembly of nozzle of the invention The nozzle apparatus of the invention can be suspended from the welding torch block in a conventional manner.

A primary advantage of the nozzle apparatus of the invention is that it allows direct viewing or remote camera viewing of the inner lower portion of the joint, without significant obstruction of sight by the filler material feeding guide nozzle. Other technical advantages include the option for multifunctional capabilities to improve other features of the joining process and complete the joint. An example of this capability is the addition of alloy enricher and dopant materials for local chemistry and control of corresponding material property. The advantages of welding productivity and other fusion processes include the ability to reduce the number of passes required to decrease bonding volume and therefore reduce the time and cost of the total process. Additional productivity advantages include the incorporation of features that would otherwise be applied as separate processes before or after the welding process is implemented, such as temperature measurements and dimensional inspections.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a nozzle assembly of filler material with cylindrical stiffener for use in a reduced width slot in accordance with a first preferred embodiment of the invention.

Fig. 2 is a diagram showing a nozzle assembly of filler material having a segmented design with planar stiffener in accordance with a second preferred embodiment of the invention. Fig. 3A is a diagram showing a nozzle assembly of filler material having a monolithic design with optional means for detection or control in accordance with a third preferred embodiment of the invention. Fig. 3B is a schematic showing a nozzle assembly of filler material having a monolithic design similar to that of Fig. 3A, but without means for detection or control. Fig. 4 is a sectional view through a weld joint of a filler nozzle assembly with an integral gas lancet having porous tubes in accordance with a variant of a fourth preferred embodiment of the invention. Figs. 5 to 10 are detailed views of the exit end of five different variations of a material nozzle assembly > - gas with integral gas lancet according to the fourth preferred embodiment, including: a variation of porous channel (Fig. 5); a variation of triple wall porous channel (Fig. 6); a multiple tube variation (Fig. 7); a variation of porous coating (Fig. 8); a variation of corrugated channel (Fig. 9); and a variation of helical spring gas distribution (Fig. 10). Fig. 11 is a diagram showing a gas dam mounted on a nozzle assembly of integral gas lancet filler material in accordance with a fifth preferred embodiment of the invention. Fig. 12A is a front view of a composite filler nozzle and a non-consumable electrode according to a sixth preferred embodiment of the invention. Fig. 12B is a side view of the non-consumable electrode incorporated in the composite structure illustrated in Fig. 12A. Fig. 12C is a detailed plan view of a hot wire variation of the preferred embodiment shown in Figs. 12A and 12B.

Detailed Description of the Preferred Embodiments The nozzle assembly of filler material of the present invention can be used as part of a welding system tungsten arc gas (GTAW) adapted for welding a groove width reduced 2 to form a welded joint 4 between parts 6a and 6b, as seen in Fig. 1. The GTAW system has "• ^ íñsíV! Tion machining torch and a tungsten electrode 8 with a geometry designed to fit in the slot of reduced width 2. The sidewalls of groove 2 preferably have the less than 5 ° acute angle. The blade electrode 8 has a noncircular cross section. in particular, the cross section of blade has an elongated dimension which is oriented parallel to the length of the weld joint and a trimmed dimension that is oriented perpendicular to the length of the joint, for example, a cylinder having a generally rectangular cross section welds 4 are deposited inside the groove 2 using the electrode tungsten alloy elongated slim 8 to melt the filler wire 10 fed into the groove through a nozzle assembly of filler materials 12A Electrode 8 fits within slot 2 with free space between the electrode and the walls later signals The blade of electrode 8 is covered optionally with a ceramic coating to prevent arcing to the sidewalls of groove 2 The welding electrode 8 powered by a power supply of conventional arc (not shown) to produce a primary arc electrode plane 8 and the nozzle assembly of flat filler material 12A, in conjunction with the small bevel angle and the selected welding parameters, produce a very thin weld joint. During welding, the arc, the welding container and the filler material can be observed using the remote viewing chamber. According to a preferred embodiment of the invention, the filler nozzle assembly 12A has a non-circular cross-section. In particular the cross-sectional shape of the filler material guide nozzle assembly is designed to be thin in a direction perpendicular to the Depth and length of the weld seam and width in a direction parallel to the seam Also, the height and / or width may be tapered along the length of the nozzle assembly in order to provide as much stiffness as possible towards the entrance end (mounted) and, to be as narrow and as thin as possible towards the exit end. The preferred form of the filler material is continuous wire, although it may have other shapes, such as gas fluidized powder. In Figs. 1 to 11 several possible designs of the non-circular nozzle apparatus are shown. It is also possible to use the filler wire or strip of non-circular cross-section, which increases the surface area and therefore improves the heat transfer area. and casting efficiency. The reasons for using a non-circular nozzle apparatus (e.g., blade-shaped) include the following: A) provide sufficient lateral stiffness to the nozzle to maintain the proper position guide of the filler metal, while providing only the minimum practical width (in a direction perpendicular to the walls) when used in reduced joints that would otherwise be too narrow to be filled; B) provide improved nozzle bending strength both parallel and perpendicular to the depth of the joint so that the desired metal filler guide is maintained, regardless of the physical handling of inadvertent handling or the abusive mechanized direction of the nozzle, C) providing a minimum nozzle width (in a direction perpendicular to the weld seam) so that the view at the junction from a remote weld display chamber is not obstructed by the portion of the nozzle passing through the view, D) provide sufficient nozzle height (in a direction parallel to the attachment depth) to allow multiple junction related functions to be implemented simultaneously, or to implement specific individual functions more efficiently and more productively with same nozzle assembly as used for the joining process; and E) allow the nozzle to extend near the A very small weld joint for powder feed additions directly into the filler metal melting container The fluidized powder, if fed from a larger nozzle not within the joint, would diverge excessively within the joint and result in a significant loss of the deposition efficiency of the filler material inside the container The non-circular nozzle assembly can be manufactured from a piece of small circular or semicircular pipe 16, therefore, . "" The tip of which is attached to a pair of steel stiffeners in bar or high strength bar 18 (see Fig 1) placed on opposite sides of the same In the alternative, only one stiffener can be used 18 The wire filler 10 is fed through line 16, with nozzle assembly 12A being positioned so that the end of filler wire 10 is located at the site of the weld bead to be formed. Line 16 (hereinafter "guide nozzle") filler ") can be made of tungsten (as produced by the chemical vapor deposition technique) or other wear resistant material, resistant to high performance, such as metallic carbide. The stiffener 18 as well as the filler guide nozzle 16 can be made from carbide, tungsten, etc., in order to produce the toughest and heat resistant nozzle assembly, most practical rigid or high strength hardened steel to produce the strongest assembly (resistant to fracture). Alternatively, a non-circular nozzle assembly 12B (shown in Fig. 2) has a circular tube 16 of very small diameter attached along its length to a stiffener such as the edge of a thin plate or sheet steel part 22. A stiffener configuration is a piece triangular thin elongated tungsten sheet (or other high performance material such as carbide) which is brazed, welded, mechanically fastened or otherwise attached to the nozzle tube .- filled with the narrow apex of the triangle at the end of exit of the tube. This configuration provides the greatest resistance against bending when the nozzle assembly is mounted on a mounting bracket 24 as a cantilever at the wide end of the triangle. The mounting bracket 24 is connected to a driving apparatus (not shown) for raising and lowering the nozzle assembly of filler material. In accordance with a further preferred embodiment, the filler nozzle assembly has multiple functions. The wire nozzle assembly ( or another form of filler material) may have different functions to guide the position of the end of the wire at work, and may be made from a tube assembly or be fabricated from other shapes to form multiple hole configurations (such as "honeycomb" type) Fig 3A shows a monolithic filling nozzle 12C having a hole 26a which serves as the filler guide nozzle and additional holes 26b-26e which serve as channels for protecting the gas detection means or of temperature, such as a resistance temperature device or an infrared fiber optic probe that is pushed through the duct The guide guides the filler material from a point outside the weld groove to a desired location within the groove, ie, in proximity to the weld filler. The filler material is guided into the nozzle by means of a conduit ~ ^ ~ Fig. 3B shows the monolithic filling nozzle 12C having only one orifice 26a which serves as a guide nozzle for filling material. The monolithic filling nozzle 12C is manufactured by machining round bar steel to form flat faces parallel or slightly tapered on sides. Opposites Alternatively, nozzle 12C can be made from steel bars In the case of a multiple tube embodiment, one or more of the tubes can be used as mechanical stiffeners and even others can perform different process functions. When tubes are used as mechanical stiffeners only, solid bars or bars made of very high yielding point and elastic modulus materials, such as full hardness steel, tungsten alloy, etc., may be replaced by those portions of the assembly. . (Hereinafter, the term "bars" will be used to mean bars and / or rods.) For maximum nozzle stiffness, all parts of the assembly are made from high rigidity and high strength materials. In any multiple bar / tube design, the lateral flexural strength of the composite assembly is significantly greater than that of an individual tube having a diameter equal to the width of the assembly. The length of the stiffener tubes or rods can be arranged at intervals shorter than the length of the filling nozzle, as required, in order to provide sufficient clearance: ^ -: at the electrode edge and towards the bottom of the Union. The nozzle may be located in a symmetrical or non-symmetrical arrangement of stiffener tubes or rods, as required, to adjust those clearances to the adjacent electrode and work surface. In accordance with a further preferred embodiment of the invention, a gas lancet incorporated in a composite gas lancet / filling nozzle assembly 12D can be used for welding gas supply (hot / melt cord and / or gas shielding gas). welding arc formation) for the local welding area, as shown in Fig 4. In some very deep joints, the gas lancet may be solely the source of welding gas. This configuration can improve the quality of the welding gas localization near the origin of the union by minimizing gas dilution, and may reduce the total flow velocity required for sufficient weld bead coverage (as compared to the practice of feeding gas from an external gas cup to the union) A primary portion or all of the welding gas can be fed directly to the lower portion of the union through the gas lancet, which comprises a multiplicity of integral gas distribution tubes 28, each tube having a non-porous section 28a acting as a conduit and a porous section 28b that acts only as a diffuser if the distal end is closed The porosity of the tube walls is indicated by means of FIG. 4. The respective tubes 28 of the gas lancet act as conduits / diffusers for the flow of primary solder gas supplied by the line 30 and the gas head 32. Optionally, a gas flow can be provided. auxiliary welding gas from above the joint by means of a conventional gas cup 34 with gas diffuser lens in order to protect the hot electrode from oxidation, as well as supplying the gas flow from the gas lancet into the joint The compositions of the gases that come from above the union and from inside the union can be different, since the gas of cover of inert cord would be provided firstly. e by the conventional gas cup 34 and, the arcing gas (with adjusted ionization potential and heat transfer properties) as well as the cover gas would be provided first by the gas lancet. The new design of the welding gas nozzle assembly described herein, which may be formed in the form of a composite lancet, may have a portion toward the outlet end of the cross-linked porous pipe material to reduce turbulence with the atmosphere outside the joint (by reducing the local flow velocity and the Reynolds number), and allowing laminar flow within the joint in the vicinity of the deposited cords. [The Reynolds number, Re = pVL / μ, where p is the density of the fluid, V is the flow velocity, L is the descriptive characteristic length of the flow field and μ is the viscosity of the The nature of the fluid (laminar or turbulent) is determined by the value of the Re number without dimension.] The outlet ends of the pipe can be closed with porous or non-porous material in order to force more gas out of the pipes. pores in the walls of the tube that would occur if the pipe were open at the ends.

Alternate construction forms of the porous material include electro-etched or laser-drilled extraction pipe or flat-side channel fabricated from sheet steel that is drilled at least near its outlet end either before or after assembly. Examples of some variations of those designs are shown in Figs. 5 to 9 The filler guide nozzle assembly 12E shown in FIG.

Fig 5 comprises a pair of weld gas flow channels with open ends 36 attached to opposite sides of the filler guide nozzle 16, each channel having a porous section 36a (indicated by speckle) and a non-porous section 36b. the channels 36 may optionally be perpendicular to the axis of the filler guide nozzle, as indicated by dotted lines in FIG. 5 In accordance with a further variation shown in FIG. 6, the porous section of each channel of a guide nozzle assembly of filler 12F may consist of multiple porous walls embedded one within the next, for example, an internal porous wall 50 of coarse-grained porosity, a porous wall ~ c < _'a 52 of medium grade porosity and an external porous wall 54 of fine grade porosity Alternatively, the filler guide nozzle assembly 12G shown in FIG. 7 comprises two arrays of parallel gas distribution pipes 38 attached to and extending from diametrically opposite sides of a filler guide nozzle 16 The arrangements of tubes of gas distribution may be non-symmetrical with respect to the filler guide nozzle. Each tube 38 has a porous section 38a (indicated by mottling) and a non-porous section 38b, analogously to the modalities previously described. The distal ends of the tubes 38 may be angled (as shown by solid lines in Fig. 7) or perpendicular (as shown by dotted lines in Fig. 7) to the axis of the filler guide nozzle and may be open or closed. According to another preferred embodiment shown in FIG. 8, a filler guide nozzle assembly 12H has an integral gas lance comprising upper and lower support frames 40 and 42 attached to the filler guide nozzle 16. A porous coating 44 is extended through the support frames 40 and 42 to form a chamber that is filled with pressurized welding gas. The porous coating can take the form of a perforated electroformed or laser drilled stainless steel sheet material. A non-porous coating (not shown) can be spread over portions of the remote support ribs of the nozzle outlet to form a conduit for transporting the welding gas to the chamber. The pressurized welding gas in the chamber diffuses through the porous coating 44 and fills the surrounding volume of the weld groove. In accordance with a further variation shown in Fig. 9, a filler guide nozzle assembly 121 comprises a thin housing 46 supported by a corrugated spine 48. The corrugations preferably move parallel to the axis of the filler guide nozzle. The peaks and valleys of the corrugations preferably contact the inner surfaces of the housing 46 to provide support and to form a series of parallel channels for welding gas flow. The thin housing 46 has a porous section 46a (indicated by mottling) and a non-porous section 46b, in a manner analogous to the previously described embodiments. The distal end of the housing 46 may be angled or perpendicular to the axis of the filler guide nozzle and may be open or closed. In accordance with the variation shown in Fig. 10, a filler guide nozzle assembly 12J comprises two parallel gas distribution tube arrangements 74 attached to and extending from diametrically opposite sides of the filler guide nozzle 16. Each tube 74 has a helical spring section 76 attached to its extreme. The end of each helical spring is closed by a plug 78, which may be the porosity of the plug and the constant spring of the coil spring are selected so that the flow of welding gas supplied by means of the line 30 and the gas head 32 under pressure will diffuse through the turns of the coil spring This creates a laminar flow of gas into the weld groove The distal ends of the coil springs 76 are preferably angled (as shown in FIG. shown in Fig. 10) In accordance with an "additional" improvement, the helical spring section may comprise coarse and fine coil springs arranged concentrically. In accordance with the broad concept of the present invention, the double lancet assemblies can be placed on the front and rear sides of the electrode, with respect to the direction of travel of the torch. These assemblies may alternatively be used depending on the direction of travel or simultaneously independent of the direction of travel, as required, to obtain sufficient flow to establish a stable arc voltage and inert gas coverage of high purity weld deposit. Referring to FIG. 11, a gas confinement or seal dam 52 can be effectively used on the front side or on the front and rear sides of the torch to confine a portion of the inert gas to the vicinity of the reservoir area of the gas. welding. These movable dams can be an integral part of the filler guide nozzle assembly, they can be mechanically attached to the assembly or, they can be mounted separately from and / or behind the lancet type of the nozzle. The dam would extend a significant distance through a significant fraction of the joint width to effectively minimize the contamination of the inert gas with the surrounding atmosphere in the groove. The dams would preferably be made of a deformable material (with a non-deformable support structure) so that a more effective seal can be obtained towards the internal surfaces of the joint. An example of this type of seal is braided metal mesh (or silicone rubber tubing or sponge) that fills an inclined helical spring, with a solid bar that passes through the mesh and extends a portion of the length of the spring. The bar is made, for example, of spring steel that has a gauge small enough to allow the bar to flex. For greater sealing efficiency, the gas dams can be mounted so that they are spring loaded in the lateral and depth directions to make essentially continuous contact with the joint walls and the source surface. Referring again to Fig. 2, optional nozzles 12b-12e may also be used to supply solid additives to the welding vessel, such as powders for alloying effects, including in-situ alloying with noble metal catalytic elements (e.g. , palladium), enrichment with elements The fissures of stress corrosion cracking (eg, chromium), or fluxes and surfactants to improve weld penetration and / or wetting can also be introduced. Additives that are not alloyed with the weld material can also be introduced. , although in their place they form a composite structure.The optional nozzles 12b-12e of the monolithic nozzle 12C can also be used to supply the main source or an auxiliary fusion heat source for the joining process, such as laser light passing to Through optical fibers in the nozzles, this variation can be specifically useful for working in very small width joints with laser systems that have higher beam quality, which allows enough focused heat to be supplied by optical fiber to the welding vessel without the need for objective lenses that span space at the end of the fiber A non-circular nozzle assembly can be made with an electronic Triangular (or bar-shaped) ear / stiffener 56 manufactured from tungsten or other suitable high-temperature alloy which functions as a non-consumable welding electrode and as a nozzle stiffener, as shown in Figs. 12A and 12B. A triangular (or bar-shaped) electrode / stiffener made from steel in tungsten alloy sheet can provide sufficient cross-sectional area at its base (width) end so that it can successfully resist unacceptable bending, as well how to transport the exceptionally high arc current without ~ - > ortar its minimum thickness. The base of the triangle is clamped or otherwise supported by an electrode holder 58. The electrode holder 58 is preferably made of an oxidation-resistant conductive material such as copper alloy (e.g., beryllium copper alloy), optionally thedetrodeposited with silver or nickel. The electrode holder preferably takes the form of a T-shaped metal body, comprising a rod 58a and a crosspiece 58b. The rod 58a is connected to a conventional welding torch (not shown). The crosspiece 58b has a longitudinal groove formed to receive the triangular blade base with sufficient clearance to allow easy insertion and removal. The blade base is held securely in the cross piece slot by holding a pair of set screws 60 in a corresponding pair of threaded holes formed in the cross piece. The blade can be easily removed from the support after the screws have been loosened. This allows easy replacement of an electrode / stiffener blade. Alternatively, instead of using screws, the blade can be secured to the support by brazing to create a monolithic blade assembly, i.e., the blade would not be easily replaceable. The blade body 56 is preferably covered with insulating coating, for example, AI2O3 or Y2O3, to avoid arcing towards the side walls of the groove. Likewise, all the thick edges on the stamped or cut ribs are removed from the burrs to avoid the following:. According to the preferred embodiment, the flat triangular blade incorporates one or more insulating spacers 62. Each spacer 62 consists of a metal piece of insulating material, for example, Al203 or Y2O3, having a cylindrical peripheral wall and a pair of surfaces in opposition slightly convex or curved edges at each end of the cylinder. As best seen in Figure 12B, each insulating distance 62 protrudes over the flat sides of the electrode blade beyond the plane of the blade surface. These spacings serve to maintain a minimum space between the side walls of the weld groove and the flat sides of the electrode / stiffener blade, thus avoiding cracking or excessive wear of the ceramic coating during displacement of the electrode in the groove of welding. A crack deep enough on the coated surface of the blade will remove the ceramic coating, leaving the blade susceptible to bowing along the uncoated place. If the filler guide nozzle 16 is electrically common with the stiffener 56, then the filler wire 10 becomes the consumable electrode, as in metallic inert gas (MIG) welding. In this case, the replaceable tip 55 (see Fig. 12A) can be removed. Alternatively, if the nozzle 16 is electrically isolated from the stiffener 56, then the stiffener is also a non-consumable electrode, as in the welding of inert tungsten gas (TIG). The optional auxiliary nozzles 64, for example,-r3 transport the inert protection gas are shown by dashed lines in Fig. 12A. In accordance with another variation shown in Fig. 12C, the filler guide nozzle 16 is welded to the stiffener 56 and a nozzle 66 for the temperature sensing means (not shown) is attached to the other side of the filler guide nozzle 16. For the case where the filler wire is a consumable electrode and a filler material, such as in MIG welding and arc welding formed from flow, the nozzle is designed to conduct electrically towards the wire in order to establish and maintain an arc. from the casting end of the wire to the work. In this variation the nozzle is electrically isolated from the rest of the welding torch. The filler guide nozzle 16 in this case comprises an electrical conductor 68 surrounded by an electrical insulator 70, which in turn is surrounded by the structural pipe. The stiffener (s) may be attached to and made electrically common (s) with the filler guide nozzle apparatus by high-temperature brazing, precision welding (e.g., laser, electron beam, electrical resistance) or other means without risk of overheating and melting the joint (s) of the assembly during use. With respect to the aforementioned welding process of the detection and control apparatus, the optional nozzles can also be used to supply visible light to the local OVad area to illuminate it for visual or mechanical inspection purposes. The light source for this purpose can be effectively delivered by an optical fiber or a group of fibers passing through one or more nozzles. The "structured light" can also be used to provide information to the monitor or to control the welding geometry. The optional nozzles can also be used to supply non-visible light (such as an infrared wavelength) to the local welding area to "illuminate" it for machine control, vision or other inspection purposes either before, during or after each junction step The light source for this purpose can also be supplied by an optical fiber or group of fibers that pass through one or more nozzles. One or more nozzles (s) can Also used with miniature borescope vision within the weld spot while monitoring the local geometry of the weld bead and the substrate This configuration can be used to obtain a sufficiently large angle view or larger enlargement of the weld bin and the Adjacent area within the joint For very narrow width joints, this method of vision may be preferred to that with a camera lens lens located outside of the joint, since the external view configuration of the field of view is restricted by the sidewall trimmer effect of the preferred narrow joint width. Other nozzles can provide position detection _ * = 'welding process or control of the characteristics of torch movement such as the lateral position of the torch at the joint, or the height position above the weld bead, such as the height detection to provide the arc length / voltage selected as in the control systems Automatic voltage (AVC) In those cases, the detection is not based on the value of the arc voltage, but on independent means such as conductive or non-contact proximity detectors With the optional nozzles equipped with optical fibers, the laser heat supplied it can also be used for other purposes than the casting of welded metal. Examples of such non-casting heat sources are prewash, preheat, cross-pass cleaning and / or post weld heat treatment (PWHT) of the welded area in order to improve the microstructural or residual stress condition of the joint., or to reduce the risk of heat cracking or various forms of delayed cracking. In accordance with a further aspect of the present invention, molded filler wire of noncircular cross section can be used to increase the surface area of the filler metal before it is fed into the heat source and, therefore, to improve the heat transfer by convection inside the material. For a given cross-sectional area of filler material, a non-circular shape has a thickness dimension that is smaller than the diameter of a circular shape of "---" i equal and, therefore, has a lower time constant for the transfer of heat by conduction through this reduced thickness. The preferred orientation for a non-circular shape is with the wide dimension that confronts the heat source. For extremely thin joints, the non-circular wire shape should be oriented with its main transverse dimension parallel to the joint depth. This orientation provides the combined ntages of the larger filler surface area, the last joint width and the increased arc length that passes through its wider surface (after impacting its edge). The heating of the filler and the casting period can thus be used efficiently for the greatest ntage in this orientation. Another ntage in decreasing the effective thickness and / or increasing the surface area of the filler wire (and the corresponding heat transfer distance for conduction towards its center) is an improvement in the thermal efficiency of cast iron and can be directly related to the desired decrease in the total heat input of the weld, and / or the desired increase in the filler deposition rate for a given heat input. By means of the same principles, the binding productivity can be increased for a total heat input by increasing the fraction of heat used to melt the filler, and decreasing the corresponding fraction of heat contributing in excess to the molten related material. Alternatively, the hole in the filler guide nozzle may be non-circular and may accommodate and maintain orientation (if desired) for continuous forms of non-circular filler material. Examples of such shapes are flat wire, ribbon or textured surface wire. A particular design of the non-circular nozzle allows a unique non-circular filler wire to be fed into the joint in order to maximize the ratio of surface area to volume of the wire and to minimize its specific thermal thickness. These characteristics solve the problem of the melting ratio of the wire being typically the time limiting step, with respect to the need to increase the deposition rate of the general filler metal. The form of non-circular filler material or surface of textured filler material may be the existing condition that was formed at a pre-juncture for a bonding application or, may be formed directly on the wire just before it is fed into the guide nozzle ( such as knurling surface or rolling shape). A variation in the shape of the filler wire applicable to the round or cross-sectional wire does not circulate the bent or twisted wire (such as in a serpentine or helical form), which provides increased heating time and melting efficiency. For a given volumetric feed rate of the filler, the length of the bent wire is effectively shorter than the corresponding length of the straight wire. Therefore, the effective linear feed rate within the heat source is slower (providing more time to be heated up to its melting temperature) than the linear speed before bending. Hereinafter pp (1) - (10), variations of the preferred embodiments of the invention are described without reference to the drawings. (1) The non-circular cross-sectional shape of the nozzle assembly can have various "flattened" shapes including elliptical, lenticular, oval, rectangular, etc. The passage for the wire (such as a hole) may be centrally located, or it may be offset to allow attachment of other appliances and / or holes for other functions on the extended edges of the nozzle. (2) The nozzle may be linear or non-linear along its axis as required, in order to accommodate optimal vision while maintaining the preferred wire entry angle (s) within the container of welding. For very deep joints and smaller wire entry angles, it may be preferable to bend the nozzle assembly up (towards the joint opening) on its inlet end to maintain its shorter length and higher its corresponding stiffness. (3) The nozzle can be manufactured as a compound of various forms of simpler component to obtain the desired general flattened (non-circular) shape, the orifice position of '-'- • mile and electrical conduction or insulation and other selected properties of the assembly. (4) The nozzle can be made from or reinforced with various metals (such as "piano / music wire", tool steel, etc.) to maintain the highest yield point resistance and modulus of elasticity and rigidity, especially perpendicular to its thickness. A composite configuration can also be used to provide adequate resistance to thermal damage and mechanical wear. (5) The nozzle can be guided by mechanical or other means to maintain it in the preferred location in the joint, such as in the central position. The guide means may be passive, such as a mechanical follower that contacts the sides of the welded joint, or active, such as a detection and control system. (6) The nozzle (s) may be mechanically (though not electrically) attached to the edge (s) of a non-consumable electrode, to improve rigidity of the thin assembly, as well as to maintain easily the alignment required between them. The heat in the electrode can also help to preheat the filler material to improve the thermal efficiency of cast iron. (7) For the case where the filler wire is only a filler material (and not a consumable electrode as well), such as in gas tungsten arc welding (also known as inert gas welding of tungsten (TIG)), The nozzle can be electrically driven to the wire to preheat the wire before melting in the arc.This method is known in the industry as "hot wire" TIG welding.If the wire is electrically preheated, the assembly The nozzle is preferably made with a heat-resistant, electrically insulating outer surface coating or structural layer to prevent possible landing to work.This insulating coating, which must have high mechanical strength and thermal impact, can be formed on the components of nozzle by thermal spray of a high temperature, strong ceramic such as alumina, zirconia or itria or mixtures thereof. The hole for the filler wire can be lined with an additional material that has increased electrical conductivity (such as beryllium, copper and silver alloys) relative to the rest of the assembly. All known designs of hot wire TIG nozzles have a significantly increased size and shape which prevents them from being set in an extremely narrow weld joint, as is possible with the nozzle configurations of the present invention. (8) The optional nozzles can be used to preheat the filler material before it enters the melting vessel with a laser beam supplied by optical fiber in a TIG configuration of hot laser wire. This configuration combines the arc sprinkling characteristic of an electric arc necessary to heat the full width and the side walls of a joint and a geometry ^ potentially variable bead surface, with the highest, most focused energy density heating characteristics of a laser source supplied by optical fiber. Said method of preheating hot wire with laser is more efficient to heat a wire of uniform geometry (straight or moderately bent) that would be significantly thinner than the joint and the width of the electric arc. (9) Still other longitudinal holes can be used in the nozzle assembly for detection or temperature control by installing thin temperature detectors, such as thermocouples or resistance temperature devices, which can measure preheat and / or interpass temperatures As required. This configuration allows the most accurate measurement of local temperatures in the hottest portion of the bead at the junction, instead of the average monitored temperatures typically measured away from the weld bead outside the joint. When multiple detectors are used, the distribution of the temperature along or through the joint can be obtained. (10) Optional nozzles can also be used for local supply of solder flux surfactants and / or solder penetration agents to increase the performance of standard composition alloys. These agents can also be used to provide acceptable solderability = difficult "high impurity" alloys with respect to! wetting and penetration control. The filler material guide nozzle of the invention provides the most accurate placement of the filler metal in the joint at the preferred position of the heat source, the reduced obstruction of the view of the interior of the joint, and the corresponding ability to improve the efficiencies volumetric and thermal bonding by allowing additional reduction of the joint width. These improvements can result in minor defects in the molten deposit, lower residual stresses, reduced heat damage in the heat-affected areas (HAZ), higher joint productivity and longevity of increased welding torch tooling. In addition, the filler material nozzle assembly incorporating a gas distributor lance provides efficiently the required welding gas locally close to the weld bead and the tip of the electrode within the joint. This is an improvement over conventional methods of inefficiently locating the gas distributor cup out of the joint or providing a gas cup around the electrode within the joint, which must then be significantly wider than is the case for the nozzle configuration of the present invention.

The filler material guide nozzle of the invention has the advantage of being usable for supplying other related joining processes, such as additions of local and doped alloy, auxiliary illumination, machine and visual inspection or formation of a gene. , measurement of weld bead and joint size, and control of the position of the torch or filling material, including other variations including preheating and interpassing the temperature measurement, pre / post heating the union, preheating the filler material, welding the preys of gas for confinement of atmosphere within the junction near the arch and others The benefits of the filler material guide nozzle described herein can be realized on most welding applications and some of the brazing applications using mechanized equipment with a local heat source at the junction, such as an electric arc or a laser supplied by optical fiber or, alternatively, with a remote heat source such as a laser beam supplied by optical lens, electronic beam, etc. The greatest benefits can be obtained when the joint design is so volumetrically small and efficient (narrow width for a given depth) that the conventional type of nozzles are too wide to fit in the joint with sufficient clearance for lateral adjustment and forward movement, or are too complex to adequately maintain precise position control of the filler material. The variation of a filler metal guide nozzle that is structurally integral with a welding gas distribution lancet that allows the depth of the joints to be successfully completed to increase beyond the practical limit of conventional practices using a blowtorch The inside of the joint or a gas cup flattened around the portion of the electrode that extends into the joint. This benefit can be achieved without making use of the undesirable practice of increasing the width and the corresponding volume of the joint. The gas lance can also be integrated with a complex gas / welding gas dam to effect stable welding in very thin, high aspect ratio joint designs.

The various designs of the filler nozzle assembly of the present invention can be used to feed the conventional form of round wire filler, as well as other forms of higher casting efficiency such as flat wire, textured wire, bent or twisted wire and, dust or powder combinations. The apparatus and methods described can be used effectively for the consumable and non-consumable electrode welding processes. For non-consumable processes, the filler material nozzle can be structurally integrated with the electrode to obtain alignment, stability and preheating, and productivity benefits. The above preferred embodiments of the invention have been described for the purpose of exemplification. Variations and modifications of the method will be evident to practitioners experienced in the welding technique. All those variations and modifications which do not depart from the concept of the present invention are intended to be encompassed by the claims set forth hereinafter.

Claims (18)

1. A filler material guide nozzle assembly having a non-circular cross-sectional shape adapted to fit in a very narrow weld slot, comprising: a nozzle (16) for guiding the filler material to a desired location within the welding groove from a location outside the welding groove, the nozzle having an outlet for the filler material at a distal end thereof; and a stiffener member (18, 22, 36, 38, 40 or 56) attached to the nozzle, wherein the nozzle and stiffener are generally located in a plane and form a structure that is stiffer than the nozzle alone.

2. The filler material guide nozzle assembly as defined in claim 1, wherein the nozzle has a channel of constant cross-sectional shape.

3. The filler material guide nozzle assembly as defined in claim 1, wherein the stiffener member comprises a rod (18).

4. The filler material guide nozzle assembly as defined in claim 1, wherein the stiffener member comprises a sheet or plate (22 or 56) having an edge attached to said nozzle.

5. The filler material guide nozzle assembly as defined in claim 1, wherein the stiffener member comprises a conduit (36, 38 or 40).

The filler material guide nozzle assembly as defined in claim 5, wherein the conduit comprises a distal section (38a) made of gas permeable material and a section connected to the distal section made of gas impervious material ( 38b).

The filler material guide nozzle assembly as defined in claim 6, wherein a distal end of the distal section of the conduit is closed.

8. The filler material guide nozzle assembly as defined in claim 5, wherein the nozzle comprises an electrical conductor (68).

9. The filler material guide nozzle assembly as defined in claim 8, wherein the electrical conductor is a tube having a channel.

10. The filler material guide nozzle assembly as defined in claim 5, further comprising an optical fiber positioned within the conduit.

11. A filler material guide nozzle assembly having a non-circular cross-sectional shape adapted to fit in a very narrow weld slot, comprising: a filler material guide nozzle (16) having a section channel constant transversal and one exit; and a gas distribution pipe (36, 38 or 40) attached to said nozzle, wherein the filler material guide nozzle and the gas distribution pipe are generally located in a flat one.

12. The filler material guide nozzle assembly as defined in claim 11, further comprising a sheet or plate (22 or 56) having an edge attached to one of the filler material guide nozzle and the distribution pipe of the filler material. gas.

The filler material guide nozzle assembly as defined in claim 12, wherein the sheet or plate (56) is made of tungsten alloy and has a tip located such that the outlet of the guide nozzle of filler material is the portion of the filler guide nozzle closest to the tip.

14. The filler material guide nozzle assembly as defined in claim 11, wherein the gas distribution pipe comprises a distal section (38a) made of gas-readable material and a section (38b) connected to the gas. distant section made of gas impermeable material.

15. The filler material guide nozzle assembly as defined in claim 14, wherein a distal end of the distal section of the gas distribution pipe is closed.

16. The filler material guide nozzle assembly as defined in claim 11, wherein the gas distribution pipe comprises a first porous wall (50) having a porosity of relatively coarse degree and a second porous wall (52). which has a relatively fine degree of porosity, the first porous wall being embedded within the second porous wall.

17. The filler material guide nozzle assembly as defined in claim 11, wherein a distal section of the gas distribution pipe comprises a helical spring (76).

18. The filler material guide nozzle assembly as defined in claim 11, further comprising a condescending gas dam (52).