JP3201246U - System for initiating and using a combination of filler wire feeder and high strength energy source for welding - Google Patents

Abstract

A welding system is provided that prevents arcing that causes melting or spattering. A welding system provides high strength energy 110 to a workpiece 115, a high strength energy source 130 that forms a weld pool in a weld joint, and heating that heats a filler wire 140 to a temperature that melts in the weld pool. A power source 170 and a wire feed mechanism 150 that advances the filler wire to maintain contact between the filler wire and the weld pool during the welding operation. The heating power source 170 observes feedback from the filler wire heating signal via the current controller 195 and stops heating the filler wire so that no arc is generated when the feedback reaches an upper threshold. [Selection] Figure 1

Description

  This application is a continuation-in-part of U.S. Patent Application No. 12/352667 and is a continuation-in-part of U.S. Patent Application No. 13/212025 claiming priority of the patent application. Insist. US patent application Ser. Nos. 13/212025 and 12/352667 are hereby incorporated by reference in their entirety.

  The present invention relates to a welding system according to claim 1. Certain embodiments relate to welding and joining operations in addition to filler wire overlaying operations. More specifically, certain embodiments include filler wire feeders for any of brazing, cladding, building up, filling, surface hardening, joining and welding operations. And a system for starting and using a system that combines an energy source.

  Conventional filler wire welding methods (eg, gas tungsten arc welding (GTAW) filler wire method) provide higher deposition rates and welding speeds than conventional arc welding alone. The filler wire preceding the torch is resistively heated by another power source. Wire is fed through the contact tip towards the workpiece and extends beyond the contact tip. The stretched portion may be resistively heated such that the stretched portion approaches or reaches the melting point and may contact the weld pool. A tungsten electrode can be used to heat and melt the workpiece to form a weld pool. The power supply provides most of the energy required to resistance melt the filler wire. Sometimes the wire feeder slips or wobbles and an electric current in the wire causes an arc between the wire tip and the workpiece. The extra heat of such an arc can cause melting and spattering. The risk of such arcing is greater at the beginning of the process where the wire initially contacts the workpiece at a small point. If the initial current in the wire is too high, the above points can burn out and cause arcing.

  Comparing the embodiments of the present invention described in the remainder of this application with the conventional, existing and proposed approaches with reference to the drawings, further limitations and disadvantages of those approaches are addressed. It becomes clear to the contractor.

U.S. Pat. No. 4,866,247 US Pat. No. 5,148,001 US Pat. No. 6,051,810 US Pat. No. 7,109,439

  The present invention aims to eliminate the above limitations and disadvantages. Furthermore, the present invention aims to minimize the risk of arcing. These problems are solved by the welding system according to claim 1. Further embodiments are the subject of the dependent claims. Embodiments of the present invention include systems and methods for initiating and using a system that combines a filler wire feeder and an energy source. A first embodiment of the present invention combines a filler wire feeder and an energy source for any of brazing, cladding, overlaying, filling, surface hardening, welding and joining operations. Relates to a method for starting and using a new system. The method includes applying a sense voltage through a power source between at least one resistive filler wire and the workpiece and advancing the distal end of the at least one resistive filler wire toward the workpiece. Including. The method includes detecting when the at least one resistive filler wire first contacts the workpiece. The method also includes turning off the power to the at least one resistive filler wire for a predetermined period in response to the detection. The method further includes turning on the power source at the end of the predetermined period to apply a flow of heating current to the at least one resistive filler wire. The method also includes applying energy from a high intensity energy source to the workpiece to heat the workpiece while applying at least the flow of heating current. The high-intensity energy source includes a laser device, a plasma arc welding (PAW) device, a gas tungsten arc welding (GTAW) device, a gas metal arc welding (GTAW) device, a flux cored arc welding (FCAW) device, and a submerged arc welding ( At least one of the SAW) devices.

  In addition to these and other features of the present invention, details of exemplary embodiments of the present invention can be more fully understood from the following description and drawings.

FIG. 1 is a schematic of an exemplary embodiment of a system that combines a filler wire delivery device and an energy source for any of brazing, cladding, overlaying, filling, and hardfacing construction. A functional block diagram is shown. FIG. 2 shows a flowchart of an embodiment of the start-up method used by the system of FIG. FIG. 3 shows a flowchart of an embodiment of the post-startup method used by the system of FIG. FIG. 4 illustrates a first exemplary embodiment of a pair of voltage and current waveforms associated with the post-startup method of FIG. FIG. 5 illustrates a second exemplary embodiment of a pair of voltage and current waveforms associated with the post-startup method of FIG. FIG. 6 shows a further exemplary embodiment of the present invention used to perform a welding operation. FIG. 6A shows a further exemplary embodiment of the present invention used to perform a welding operation. 7, 7A and 7B show additional exemplary embodiments of welding using the present invention. FIG. 8 shows a further exemplary embodiment in which both sides of the joint are joined simultaneously. FIG. 9 shows another exemplary embodiment of welding using the present invention. FIG. 10 shows another exemplary embodiment of the present invention in welding a joint using multiple lasers and wires. FIG. 11A shows an exemplary embodiment of a contact chip used in an embodiment of the present invention. FIG. 11B shows an exemplary embodiment of a contact chip used in an embodiment of the present invention. FIG. 11C shows an exemplary embodiment of a contact chip used in an embodiment of the present invention. FIG. 12 shows a hot wire power supply system according to an embodiment of the present invention. FIG. 13A illustrates voltage and current waveforms formed according to an exemplary embodiment of the present invention. FIG. 13B shows voltage and current waveforms formed according to an exemplary embodiment of the present invention. FIG. 13C shows voltage and current waveforms formed according to an exemplary embodiment of the present invention. FIG. 14 shows another welding system according to an exemplary embodiment of the present invention. FIG. 15 illustrates an exemplary embodiment of a weld pool formed in accordance with an embodiment of the present invention. 16A-16F illustrate an exemplary embodiment of utilizing a weld pool and laser beam according to an embodiment of the present invention. FIG. 17 shows a welding system according to another exemplary embodiment of the present invention. FIG. 18 shows an exemplary embodiment of a ramp-down circuit that can be used in an embodiment of the present invention. FIG. 19 shows an exemplary embodiment of a fume discharge nozzle according to the present invention. FIG. 20A shows the results of a thin-wall welding process using an arc welding method. FIG. 20B shows the results of an exemplary embodiment of a thin-wall welding process using the present invention.

  As used herein, the term “overlaying” is used in a broad sense and can mean any application including brazing, cladding, overlaying, filling and surface hardening. For example, in “brazing” construction, metal filler is dispersed by capillarity between tight surfaces of the joint. On the other hand, in the “brazing welding” construction, the metal filler is allowed to flow into the gap. However, as used herein, both of these techniques are referred to as build-up construction in a broad sense.

FIG. 1 illustrates a system 100 that combines a filler wire feeder and an energy source for performing any one of brazing, cladding, overlaying, filling, surface hardening and joining / welding operations. FIG. 2 shows a schematic functional block diagram of an exemplary embodiment. System 100 includes a laser subsystem that can focus laser beam 110 onto workpiece 115 to heat workpiece 115. The laser subsystem is a high intensity energy source. The laser subsystem may be any type of high energy laser source, including but not limited to carbon dioxide laser systems, Nd: YAG laser systems, Yb disk laser systems, YB fiber laser systems, fiber transmission laser systems or direct diode laser systems. Is mentioned. Also, even white light laser or quartz light laser type systems can be used if they have sufficient energy. Other embodiments of the system include an electron beam that serves as a high intensity energy source, a plasma arc welding subsystem, a gas tungsten arc welding subsystem, a gas metal arc welding subsystem, a flux cored arc welding subsystem, and a submerged At least one of the arc welding subsystems may be included. In the following, reference will be made repeatedly to laser systems, beams and power sources in the present specification, but it will be understood that such references are merely exemplary because any high intensity energy source may be used. For example, a high intensity energy source can provide at least 500 W / cm ² . The laser subsystem includes a laser device 120 and a laser power source 130, and the laser device 120 and the laser power source 130 are operatively connected to each other. The laser power source 130 supplies power to the laser device 120 in order to operate the laser device 120.

  The system 100 provides at least one resistive filler wire 140 and can deliver a hot filler wire that can contact the workpiece 115 in the vicinity of the laser beam 110. Also includes a feeder subsystem. Of course, referring to workpiece 115 herein, the reference to contact with workpiece 115 includes contact with the molten pool, since the molten pool is considered to be part of workpiece 115. I understand. The hot filler wire feeder subsystem includes a filler wire feeder 150, a contact chip 160 and a hot wire power supply 170. In operation, the filler wire 140 preceding the laser beam 110 is resistively heated by a current from a hot wire welding power source 170 operatively connected between the contact tip 160 and the workpiece 115. According to one embodiment of the present invention, hot wire welding power source 170 is a pulsed direct current (DC) power source, although alternating current (AC) or other types of power sources are possible as well. The wire 140 is fed from the filler wire feeder 150 toward the workpiece 115 through the contact tip 160 and extends beyond the contact tip 160. The stretched portion of wire 140 is resistively heated so that the stretched portion approaches or reaches the melting point before contacting the weld pool on the workpiece. The laser beam 110 serves to melt a part of the base material of the workpiece 115 to form a weld pool and to melt the wire 140 on the workpiece 115. The power source 170 provides most of the energy required to resistance melt the filler wire 140. According to other particular embodiments of the present invention, the feeder subsystem may be capable of providing one or more wires simultaneously. For example, a first wire may be used to provide surface hardening and / or corrosion resistance to the workpiece, and a second wire may be used to add structure to the workpiece.

  The system 100 moves the laser beam 110 and the resistive filler wire 140 along the workpiece 115 (at least in a relative sense) so that the laser beam 110 (energy source) and the resistive filler wire 140 maintain a fixed relationship. It further includes a motion control subsystem that can be moved in the same direction 125. According to various embodiments, the relative movement of the workpiece 115 and the laser / wire combination is achieved by actually moving the workpiece 115 or by moving the laser device 120 and the hot wire feeder subsystem. obtain. In FIG. 1, the motion control subsystem includes a motion controller 180 operatively connected to a robot 190. The motion controller 180 controls the operation of the robot 190. The robot 190 is operatively connected to the workpiece 115 (eg, mechanically fixed) and directs the workpiece 115 so that the laser beam 110 and the wire 140 move effectively along the workpiece 115. Move to 125. According to an alternative embodiment of the present invention, the laser device 120 and the contact tip 160 can be integrated into one head. The head can be moved along the workpiece 115 by a motion control subsystem operatively connected to the head.

  In general, there are several ways to move the high intensity energy source / hot wire relative to the workpiece. For example, if the workpiece is round, the high intensity energy source / hot wire may be fixed and the workpiece may be rotated under the high intensity energy source / hot wire. Alternatively, move the robot arm or linear tractor parallel to the round workpiece and, for example, continuously move the high intensity energy source / hot wire or index once every rotation when the workpiece is rotated. The surface of a round workpiece may be built up. If the workpiece is flat or at least not round, the workpiece can be moved under a high intensity energy source / hot wire as shown in FIG. However, a robot arm or linear tractor or beam mounted carriage may be used to move the high intensity energy source / hot wire head relative to the workpiece.

  System 100 further includes a sensing / current control subsystem 195. The sensing / current control subsystem 195 is operatively connected to the workpiece 115 and the contact tip 160 (ie, effectively connected to the output of the hot wire power supply 170), and the potential difference between the workpiece 115 and the hot wire 140 ( That is, voltage V) and current (I) through workpiece 115 and hot wire 140 can be measured. The sensing / current control subsystem 195 can further calculate a resistance value (R = V / I) and / or a power value (P = V × I) from the measured voltage and current. Also good. In general, when the hot wire 140 is in contact with the workpiece 115, the potential difference between the hot wire 140 and the workpiece 115 is 0 volts or very close to 0 volts. As a result, the sensing / current control subsystem 195 can detect when the resistive filler wire 140 is in contact with the workpiece 115. Also, as described in more detail later herein, the sensing / current control subsystem 195 is hot so that it can further control the flow of current through the resistive filler wire 140 in response to such sensing. The wire power supply 170 is operatively connected. According to other embodiments of the present invention, the sense / current controller 195 can be an integral part of the hot wire power supply 170.

  According to an embodiment of the present invention, the motion controller 180 may be further operatively connected to the laser power source 130 and / or the sensing / current controller 195. In this manner, the motion controller 180 and the laser power supply 130 communicate with each other so that the laser power supply 130 knows when the workpiece 115 is moving and the motion controller 180 knows whether the laser device 120 is active. Also good. Similarly, in this manner, the motion controller 180 and the sense / current controller 195 allow the sense / current controller 195 to know when the workpiece 115 is moving and the hot filler wire feeder subsystem is active. May communicate with each other so that the motion controller 180 knows. Such communication can be used to coordinate activities between the various subsystems of system 100.

  FIG. 2 shows a flowchart of an embodiment of a startup method 200 used by the system 100 of FIG. In step 210, a sense voltage is applied by the power source 170 between the at least one resistive filler wire 140 and the workpiece 115. The sense voltage can be applied by hot wire power supply 170 under the command of sense / current controller 195. Furthermore, according to one embodiment of the present invention, the applied sense voltage does not provide sufficient energy to heat the wire 140 significantly. In step 220, the distal end of the at least one resistive filler wire is advanced toward the workpiece 115. This advance is performed by the wire feeder 150. In step 230, it detects when the distal end of the at least one resistive filler wire 140 first contacts the workpiece 115. For example, the sense / current controller 195 may instruct the hot wire power supply 170 to provide a very low level of current (eg, 3-5 amps) to the hot wire 140. Such sensing is achieved by sensing / current controller 195 measuring a potential difference of about 0 volts (eg, 0.4V) between filler wire 140 (eg, via contact tip 160) and workpiece 115. obtain. When the distal end of the filler wire 140 is shorted to the workpiece 115 (i.e., in contact with the workpiece), a significant voltage (above 0 volts) between the filler wire 140 and the workpiece 115 The level may not exist.

  In step 240, in response to the detection, the power supply 170 is turned off for a predetermined period (eg, several milliseconds) for at least one resistive filler wire 140. The sense / current controller 195 can instruct the power supply 170 to turn off. In step 250, the power source 170 is turned on at the end of the predetermined period to apply a heating current flow to the at least one resistive filler wire 140. The sense / current controller 195 can instruct the power supply 170 to turn on. In step 260, energy from the high intensity energy source 110 is applied to the workpiece 115 while applying a flow of at least a heating current to heat the workpiece 115.

  Optionally, the method 200 stops the advancement of the wire 140, resumes the advancement of the wire 140 at the end of the predetermined period (ie, advances again), and applies a flow of heating current in response to the detection. Verifying that the distal end of the filler wire 140 is still in contact with the workpiece 115 prior to doing so. The sense / current controller 195 may instruct the wire feeder 150 to stop feeding and instruct the system 100 to wait (eg, several milliseconds). In such embodiments, the sense / current controller 195 is operatively connected to the wire feeder 150 to command the wire feeder 150 to start and stop. The sense / current controller 195 may instruct the hot wire power supply 170 to apply a heating current to heat the wire 140 and to re-feed the wire 140 toward the workpiece 115.

  When the start-up method is complete, the system 100 may enter a post-start mode of operation. In this mode, the laser beam 110 and hot wire 140 are moved relative to the workpiece 115 to perform one of brazing, cladding, overlaying, surface hardening, or welding / joining operations. It is. FIG. 3 shows a flowchart of an embodiment of a post start-up method 300 used by the system 100 of FIG. In step 310, energy (eg, laser beam 110) and / or heated workpiece from a high intensity energy source (eg, laser device 120) when at least one resistive filler wire 140 is fed toward workpiece 115. The distal end of at least one resistive filler wire 140 is of high strength so that piece 115 (ie, workpiece 115 is heated by laser beam 110) melts the distal end of filler wire 140 onto workpiece 115. The high intensity energy source (eg, laser device 120) and at least one resistive filler wire 140 are moved along the workpiece 150 to precede or coincide with the energy source (eg, laser device 120). Motion controller 180 instructs robot 190 to move workpiece 115 in conjunction with laser beam 110 and hot wire 140. The laser power supply 130 operates by supplying power to the laser device 120 in order to form the laser beam 110. The hot wire power supply 170 supplies current to the hot wire 140 when instructed by the detection / current controller 195.

  In step 320, each time at least one resistive filler wire 140 is about to lose contact with workpiece 115, it is detected (ie, providing predictive capability). Such detection is accomplished by a premonition circuit in the sense / current controller 195, where the potential difference (dv / dt), resistance (dr / dt), filler wire 140 and filler wire 140 and workpiece 150 are This can be achieved by measuring the rate of change of one of the current (dr / dt) or power (dp / dt) through the workpiece 150. When this rate of change exceeds a predetermined value, the sense / current controller 195 formally predicts that contact will soon be lost. Such prediction circuits are well known in the arc welding art.

  As the distal end of the wire 140 is highly melted by heating, the distal end tears away from the wire 140 and begins to move onto the workpiece 115. For example, the potential difference or voltage at that time increases because the distal end is shredded and the cross-section of the distal end of the wire rapidly decreases. Thus, by measuring such rate of change, the system 100 can predict when the distal end will be shredded and contact with the workpiece 115 will be lost. Also, if contact is lost completely, a potential difference (ie, voltage level) significantly greater than 0 volts can be measured by the sense / current controller 195. If the action in step 330 is not taken, this potential difference can cause an (undesirable) arc to form between the new distal end of wire 140 and workpiece 115. Of course, in other embodiments, the wire 140 is not clearly torn, but flows continuously into the melt pool while maintaining a substantially constant cross-sectional melt.

  In step 330, the flow of heating current through the at least one resistive filler wire 140 in response to detecting that contact between the distal end of the at least one resistive filler wire 140 and the workpiece 115 is about to be lost. Is turned off (or at least significantly, for example, reduced by 95%). When the sense / current controller 195 determines that contact is about to be lost, the controller 195 instructs the hot wire power supply 170 to stop (or at least significantly reduce) the current being supplied to the hot wire 140. Thus, unnecessary arc formation is prevented, and undesirable effects such as spattering or melting off are prevented.

  In step 340, a detection is made each time the distal end of at least one resistive filler wire 140 comes into contact with workpiece 115 again as wire 140 continues to advance toward workpiece 115. Such sensing may be achieved by sensing / current controller 195 measuring a potential difference of about 0 volts between filler wire 140 (eg, via contact tip 160) and workpiece 115. When the distal end of the filler wire 140 is shorted to the workpiece 115 (ie, in contact with the workpiece), a significant voltage level greater than 0 volts is present between the filler wire 140 and the workpiece 115. May not exist. As used herein, the expression “contact again” means that the wire 140 advances toward the workpiece 115 regardless of whether the distal end of the wire 140 is actually completely shredded from the workpiece 115. This means a situation where the voltage measured between 140 (eg, via contact tip 160) and workpiece 115 is about 0 volts. In step 350, a flow of heating current through the at least one resistive filler wire is reapplied in response to detecting that the distal end of the at least one resistive filler wire has again contacted the workpiece. The sense / current controller 195 may instruct the hot wire power supply 170 to reapply the heating current to continue heating the wire 140. This process can be continued during overlaying.

  For example, FIG. 4 shows a first exemplary embodiment of a pair of voltage waveform 410 and current waveform 420 associated with the post-startup method 300 of FIG. Voltage waveform 410 is measured between contact tip 160 and workpiece 115 by sense / current controller 195. Current waveform 420 is measured by sensing / current controller 195 through wire 140 and workpiece 115.

  Each time the distal end of the resistive filler wire 140 is about to lose contact with the workpiece 115, the rate of change of the voltage waveform 410 (ie, dv / dt) exceeds a predetermined threshold and a tear is likely to occur. (See slope at point 411 of waveform 410). Alternatively, the rate of change in current (di / dt), rate of change in power (dp / dt), or filler wire 140 through the filler wire 140 and workpiece 115 to indicate that a tear is likely to occur. The rate of change in resistance (dr / dt) between the workpiece 115 and the workpiece 115 may be used. Such change rate prediction techniques are known in the art. At that point, the sense / current controller 195 commands the hot wire power supply 170 to stop (or at least significantly reduce) the flow of current through the wire 140.

  When the sense / current controller 195 detects that the distal end of the filler wire 140 is again in tight contact with the workpiece 115 after a period of time 430 (eg, the voltage level drops back to about 0 volts at point 412), The sense / current controller 195 instructs the hot wire power supply 170 to ramp up the current flow through the resistive filler wire 140 toward a predetermined output current level 450 (see lamp 425). According to an embodiment of the present invention, the ramp-up starts from a predetermined set value 440. This process is repeated as the energy source 120 and wire 140 move relative to the workpiece 115 and the wire feeder 150 advances the wire 140 toward the workpiece 115. In this manner, contact between the distal end of wire 140 and workpiece 115 is generally maintained, and arc formation between the distal end of wire 140 and workpiece 115 is prevented. The ramping of the heating current helps to prevent the rate of change of voltage from being misinterpreted as such when there is no shred or arc condition. Large changes in current can cause erroneous voltage measurements to be driven by inductance in the heating circuit. When the current is gradually increased, the effect of inductance is reduced.

  FIG. 5 illustrates a second exemplary embodiment of a pair of voltage waveform 510 and current waveform 520 associated with the post-startup method of FIG. The voltage waveform 510 is measured by the sense / current controller 195 between the contact tip 160 and the workpiece 115. Current waveform 520 is measured by sense / current controller 195 through wire 140 and workpiece 115.

  Each time the distal end of the resistive filler wire 140 is about to lose contact with the workpiece 115, the rate of change of the voltage waveform 510 (ie, dv / dt) exceeds a predetermined threshold and a tear is likely to occur. (See slope at point 511 of waveform 510). Alternatively, the rate of change in current (di / dt), rate of change in power (dp / dt), or filler wire 140 through the filler wire 140 and workpiece 115 to indicate that a tear is likely to occur. The rate of change in resistance (dr / dt) between the workpiece 115 and the workpiece 115 may be used. Such change rate prediction techniques are known in the art. At that point, the sense / current controller 195 commands the hot wire power supply 170 to stop (or at least significantly reduce) the flow of current through the wire 140.

  When the sense / current controller 195 detects that the distal end of the filler wire 140 is again in tight contact with the workpiece 115 after a period of time 530 (eg, the voltage level drops back to approximately 0 volts at point 512) The sense / current controller 195 instructs the hot wire power supply 170 to apply a flow of heating current through the resistive filler wire 140. This process is repeated as the energy source 120 and wire 140 move relative to the workpiece 115 and the wire feeder 150 advances the wire 140 toward the workpiece 115. In this manner, contact between the distal end of wire 140 and workpiece 115 is generally maintained, and arc formation between the distal end of wire 140 and workpiece 115 is prevented. In this case, since the heating current is not gradually ramped, the predetermined voltage measurement can be ignored as inadvertent or incorrect due to inductance in the heating circuit.

  In summary, a method and system for initiating and using a system that combines a wire feeder and an energy source for any one of brazing, cladding, overlaying, filling, and hardfacing construction is provided. Disclosed. High intensity energy is applied to the workpiece to heat the workpiece. One or more resistive filler wires are fed towards the workpiece at the location of the applied high-intensity energy or just before it. It is realized that one or more resistive filler wires are detected in contact with the workpiece at or near the location of high intensity energy to which it is applied. The heating current to the one or more resistive filler wires is controlled based on whether the distal end of the one or more resistive fillers is in contact with the workpiece. The applied high intensity energy and the one or more resistive filler wires are moved in the same direction in a fixed relationship along the workpiece.

  In a further exemplary embodiment, the systems and methods of the present invention are used for welding or joining operations. In the embodiments described above, the focus was on the use of metal fillers in the build-up operation. However, aspects of the present invention can be used in welding and joining applications where metal fillers are used and the workpieces are joined using a welding operation. The previously described embodiments, systems and methods relate to building up a metal filler, but are similar to those used in the welding operations described in more detail below. Therefore, in the following description, it will be understood that the above description is generally applicable unless otherwise specified. Also, the following description may include references to FIGS.

  In welding / joining operations, it is generally known to join a plurality of workpieces together in a welding operation, and a metal filler coalesces with at least a portion of the workpiece metal to form a joint. Due to the desire to increase manufacturing throughput in welding operations, there is a constant demand for welding operations that do not result in faster, substandard quality welds. Furthermore, there is a need to provide a system that can quickly weld under adverse environmental conditions such as remote work sites. As will be described below, the exemplary embodiments of the present invention provide significant advantages over existing welding techniques. Such benefits include, but are not limited to: low overall heat input, low workpiece deformation, very fast welding travel speed, very low spatter rate, shielding It can be welded without a spatter, can be welded at high speed with a plating material or a coating material with little or no spatter, and can be joined at high speed complex materials.

  In exemplary embodiments of the present invention, very fast welding speeds can be obtained using a coated workpiece when compared to arc welding. Coated workpieces usually require extensive preparatory work and are slow welding processes that use arc welding. For example, the following description focuses on welding galvanized workpieces. Metal galvanization is used to increase the corrosion resistance of such metals, which is desirable in many industrial applications. However, there are problems with welding conventional galvanized workpieces. Specifically, zinc in the galvanization is vaporized during welding, and when the weld pool is solidified, this zinc vapor is trapped in the weld pool and creates porosity. This porosity adversely affects the strength of the welded joint. Therefore, existing welding techniques require a first step (which is inefficient and delays) that removes the galvanization or welds through the galvanization at a slow processing rate with some defects. Or it is necessary to perform the welding process slowly. By slowing down the process, the weld pool remains molten for a longer period of time, so that the vaporized zinc escapes. However, because of the slow speed, the production speed is slow and the overall heat input to the weld can be high. Other coatings that can cause similar problems include, but are not limited to, paints, stamping lubricants, glass linings, aluminized coatings, surface heat treatments, nitriding or carbonizing treatments, cladding treatments or other vaporizing coatings or materials. It is done. As described below, the exemplary embodiment of the present invention overcomes these problems.

  6 and 6A show a typical lap joint. In this figure, two coated (eg galvanized) workpieces W1 / W2 are joined by lap welding. In addition to the lap joint surfaces 601 and 603, the surface 605 of the workpiece W1 is first covered with a coating. In a general welding operation (such as MIG), a part of the covering surface 605 is melted. This is due to the general depth of penetration of standard welding operations. Since the surface 605 is melted, the coating on the surface 605 is vaporized, but because the distance from the surface 605 to the surface of the weld pool is large, gas can be trapped when the melt pool solidifies. This problem does not occur when the embodiment of the present invention is used.

  As shown in FIGS. 6 and 6A, a laser beam 110 is directed from a laser device 120 to a weld joint, specifically surfaces 601 and 603. The laser beam 110 is of an energy density that forms a molten pool 601A and 603A for melting a part of the welding surface to form a general weld pool. Also, the filler wire 140 (heated resistance as described above) is directed to the weld pool to provide the necessary filler for the weld bead. Unlike most welding processes, the filler wire 140 contacts the weld puddle during the welding process and enters the weld puddle. This is because the process does not use a welding arc to move the filler wire 140, but simply melts the filler wire in the weld pool.

  Filler wire 140 is preheated to or near its melting point so that it does not cool or solidify the weld pool significantly even if it is present in the weld pool and is quickly consumed in the weld pool ( consumed). The general operation and control of the filler wire 140 is the same as previously described in connection with the overlaying embodiment.

  Since the laser beam 110 can be accurately focused and directed to the surface 601/603, the penetration depth for the molten pool 601A / 603A can be accurately controlled. By carefully controlling this depth, embodiments of the present invention prevent unnecessary penetration or melting of the surface 605. Since the surface 605 is not melted overtly, the coating on the surface 605 does not vaporize and is not confined to the weld pool. Also, the coatings on the surfaces of the weld joints 601 and 603 are easily vaporized by the laser beam 110, allowing the gas to escape from the weld area before the weld pool solidifies. It may be useful to use a gas exhaust system to remove the vaporized coating material.

  Because the depth of penetration of the weld pool can be accurately controlled, the welding speed of the coated workpiece can be significantly increased while minimizing or eliminating porosity. In some arc welding systems, excellent moving speed can be obtained for welding, but problems such as porosity and spatter can occur at high speeds. In exemplary embodiments of the present invention, very fast moving speeds can be achieved with no or low porosity or spatter (as described herein), and in fact, for many different types of welding operations. Therefore, a moving speed exceeding 50 inches / minute can be easily realized. Embodiments of the present invention can achieve welding travel speeds in excess of 80 inches / minute. In other embodiments, moving speeds of 100 to 150 inches / minute can be achieved with no or minimal porosity or spatter as described herein. Of course, the speed obtained is a function of the workpiece properties (thickness and composition) and the wire properties (eg diameter), but these speeds vary in many different ways when using embodiments of the present invention. It can be easily obtained for welding and joining applications. Also, these velocities can be achieved with 100% carbon dioxide shielding gas or without any shielding. In addition, these moving speeds can be achieved without forming any weld pool and removing any surface coating prior to welding. Naturally, it is conceivable that a higher moving speed can be realized. In addition, these high speeds can be achieved with thinner workpieces 115 because there is less heat input to the weld. In general, thinner workpieces 115 typically have slower welding speeds because the heat input must be kept small to avoid deformation. Embodiments of the present invention can not only achieve the above fast moving speed with or without porosity or spatter, but can also achieve very high deposition rates with low mixing. Specifically, embodiments of the present invention can achieve a deposition rate of 10 lb / hr with no shielding gas and no or low porosity or spatter. In some embodiments, the deposition rate is 10-20 lb / hour.

  In the exemplary embodiment of the present invention, these very fast movement speeds are achieved with no or little porosity and spatter. The porosity of the weld can be determined by observing the cross section and / or length of the weld bead to determine the porosity rate. The cross-sectional porosity rate is the ratio of the total area of porosity in a given cross-section to the total cross-sectional area of the welded joint at that point. The length porosity ratio is the accumulated total length of voids in a predetermined unit length of the welded joint. Embodiment of this invention can obtain said moving speed in a state whose cross-sectional porosity is 0 to 20%. Therefore, the porosity of the weld bead without bubbles or voids is 0%. In other exemplary embodiments, the cross-sectional porosity can be 0-10% and in another exemplary embodiment can be 2-5%. In some welding applications, some degree of porosity is acceptable. Also, in the exemplary embodiment of the present invention, the length porosity of the weld is 0-20% and may be 0-10%. In a further exemplary embodiment, the length porosity rate is 1-5%. Therefore, for example, a weld having a cross-sectional porosity of 2 to 5% and a length porosity ratio of 1 to 5% can be formed.

Furthermore, in the embodiment of the present invention, welding can be performed at the above moving speed with little or no spatter. Spatter is caused by the droplets of the weld pool splashing out of the weld area. When weld spatter occurs, the quality of the weld can be compromised and production can be delayed. This is because it is common to sputter off the workpiece after the welding process. Therefore, there is a great advantage in performing welding at high speed without sputtering. In the embodiment of the present invention, welding can be performed at the above-described fast moving speed at a spatter factor of 0 to 0.5. Here, the sputter coefficient is the weight (mg) of the sputter with respect to the predetermined moving distance X / the weight (kg) of the consumed filler wire 140 with respect to the same distance X. That is,
Sputtering coefficient = (Spatter weight (mg) / Consumed filler wire weight (kg))
The distance X should be such that a representative sample of the weld joint can be extracted. That is, if the distance X is too short, for example 0.5 inches, it does not represent a weld. Therefore, a welded joint with a sputter coefficient of 0 has no spatter for the filler wire consumed over the distance X, and a weld with a sputter coefficient of 2.5 has a spatter of 5 mg for 2 kg of consumed filler wire. was there. In the exemplary embodiment of the present invention, the sputtering coefficient is 0-1. In a further exemplary embodiment, the sputter coefficient is 0-0.5. In another exemplary embodiment of the present invention, the sputtering coefficient is between 0 and 0.3. It should be noted that embodiments of the present invention can achieve the above sputtering coefficient range with or without external shielding including either shielding gas or flux shielding. Furthermore, the above sputter coefficient range can be achieved without the need to remove the galvanization prior to the welding operation when welding coated or uncoated workpieces that include galvanized workpieces.

  There are many ways to measure spatter for welded joints. One method may include the use of a “spatter boat”. In such a method, a representative sample of the weld is placed in a sufficiently sized container that can capture all or substantially all of the spatter produced by the weld bead. The vessel or part of the vessel, eg the top, can be moved with the welding process so that spatter is captured. Generally, since a boat is made of copper, spatter does not adhere to the surface. A typical weld is performed on the bottom of the vessel so that spatter formed during the welding falls into the vessel. Observe the amount of filler wire consumed during welding. After the welding is complete, the sputter boat is weighed by a device with sufficient accuracy to determine if there is a difference in the weight of the vessel before and after welding. This difference represents the weight of the sputter and is divided by the amount of filler wire consumed (kg). Alternatively, if the spatter does not adhere to the boat, it can be weighed by removing the spatter.

  As described above, the depth of the weld pool can be accurately controlled by using the laser device 120. Further, by using the laser 120, the size and depth of the weld pool can be easily adjusted. This is because the laser beam 110 can be easily focused / unfocused or its beam intensity can be changed very easily. With these capabilities, the heat distribution on the workpieces W1 and W2 can be accurately controlled. This control allows the formation of a very narrow weld pool for precision welding, as well as minimizing the size of the weld area on the workpiece. This also provides an advantage in minimizing the area of the workpiece that is not affected by the weld bead. In particular, the impact of the work area adjacent to the weld bead from the welding operation is minimized. This is usually not the case with arc welding operations.

  In an exemplary embodiment of the present invention, the shape and / or strength of the beam 110 can be adjusted / changed during the welding process. For example, it may be necessary to change the penetration depth at a particular location on the workpiece or to change the size of the weld bead. In such embodiments, the shape, strength and / or size of the beam 110 can be adjusted during the welding process to provide the necessary changes in welding parameters.

  As previously described, filler wire 140 affects the same weld pool as laser beam 110. In the illustrated embodiment, filler wire 140 affects the weld pool at the same location as laser beam 110. However, in other exemplary embodiments, filler wire 140 can affect the same weld pool away from the laser beam. In the embodiment shown in FIG. 6A, filler wire 140 follows beam 110 during the welding operation. However, it is not a requirement because the filler wire 140 can be placed in a preceding position. The present invention is not limited in this respect. This is because filler wire 140 can be located elsewhere relative to laser beam 110 as long as filler wire 140 affects the same weld pool as beam 110.

  The above embodiments have been described in the context of a workpiece having a coating such as galvanizing. However, embodiments of the present invention can also be used for workpieces that do not have a coating. Specifically, the same welding process as described above can be used for uncoated workpieces. Such an embodiment can achieve the same performance attributes as previously described in connection with the dressing.

  Also, the exemplary embodiments of the present invention are not limited to welding steel workpieces and can be used for welding aluminum or more complex metals (discussed further below).

  Another advantageous aspect of the present invention relates to shielding gas. In a typical arc welding operation, shielding gas or shielding flux is used to prevent atmospheric oxygen and nitrogen or other harmful elements from interacting with the weld pool and metal transition. Such obstacles can be detrimental to the quality and appearance of the weld. Therefore, in almost all arc welding processes, shielding gas supplied externally, shielding gas formed by consumption of electrodes on which flux is formed (for example, stick electrodes or flux cored electrodes) or externally supplied. The use of a granular flux (eg, sub-arc welding) provides shielding. Also, special welding gas mixtures must be used in some welding operations, such as special metal welding or galvanized workpiece welding. Such a mixture can be very expensive. In addition, when welding is performed in an extreme environment, it is usually difficult to transport a large amount of shielding gas to the workplace (for example, in a pipeline) or wind tends to keep the shielding gas away from the arc. In recent years, the use of fume exhaust systems has increased. These systems tend to remove fumes, but when they are placed close to the welding operation, they also tend to pull away the shielding gas.

  The advantages of the present invention include that no shielding gas is used during welding or the amount thereof can be minimized. Alternatively, embodiments of the present invention allow the use of shielding gas that is not normally used in certain welding operations. This is further explained below.

  When welding common (uncoated) workpieces in an arc welding process, shielding is required regardless of the form. It has been found that no shielding is required when welding is performed using embodiments of the present invention. That is, there is no need to use shielding gas, granular flux and self-shielding electrode. However, unlike the arc welding process, the present invention produces a high quality weld. In other words, the welding speed described above can be realized without using any shielding. This was not possible with prior art arc welding processes.

  During a typical arc welding process, filler wire droplets are transferred from the filler wire to the weld pool through a welding arc. Without shielding, the entire surface of the droplets is exposed to the atmosphere during transport, which tends to take up nitrogen and oxygen in the atmosphere and carry the nitrogen and oxygen into the weld pool. This is undesirable.

  In the present invention, since the filler wire is transported to the weld without using droplets or similar processes, the filler wire is not exposed to the atmosphere so much. Thus, for many welding applications, the use of shielding is not required. Therefore, in the embodiment of the present invention, not only can a high welding speed be realized with no or little porosity or spatter, but it can be realized without using a shielding gas.

  Since it is not necessary to use a shield, the fume discharge nozzle can be placed very close to the weld joint during welding, providing a more efficient and more effective fume discharge. When the shield gas is used, it is necessary to dispose the fume discharge nozzle in a place where the fume discharge nozzle does not interfere with the function of the shield gas. Because of the advantages of the present invention, there is no such limitation and fume emissions can be optimized. For example, in the exemplary embodiment of the present invention, the laser beam 110 is protected by a laser shroud assembly 1901 that protects the laser beam from the laser 120 to near the surface of the workpiece 115. This is illustrated in FIG. A shroud 1901 (shown in cross section) protects the laser beam 110 from damage and provides additional safety during operation. Further, the shroud can be coupled to a fume exhaust system 1903 that moves the welding fume away from the welding area. Because the embodiment can be used without shielding gas, the shroud 1901 can be placed very close to the weld to move the fume directly away from the weld area. Indeed, the shroud 1901 can be positioned such that its distance Z above the weld is 0.125 to 0.5 inches. Of course, other distances can be used, but care must be taken not to interfere with weld pools or significantly reduce the efficiency of the shroud 1901. Since the fume exhaust system 1903 is generally understood and known in the welding industry, a detailed description of their configuration and operation is omitted herein. Although FIG. 19 shows a shroud 1901 that protects only the beam 110, it is of course possible to configure the shroud 1901 so as to surround at least a part of the wire 140 and the contact tip 160. For example, the bottom opening of the shroud 1901 can be made large enough to substantially cover the entire weld pool or larger than the weld pool to increase fume emissions.

In exemplary embodiments of the present invention used for welding coated workpieces such as galvanized workpieces, a cheaper shielding gas may be used. For example, 100% CO ₂ shielding gas can be used to weld many different materials including mild steel. This is also true when welding more complex metals such as stainless steel, duplex steel or super duplex stainless steel that can be welded only with 100% nitrogen shielding gas. In typical arc welding operations, welding of stainless steel, duplex steel or super duplex stainless steel requires a more complex mixture of fairly expensive shielding gases. In the embodiment of the present invention, these steels can be welded only with a shielding gas of 100% nitrogen. In other embodiments, these steels can be welded without shielding gas. In a typical welding process for galvanized material, a special mixed shielding gas such as an argon / CO ₂ mixture must be used. This type of gas needs to be used in part because the cathode and anode are present in the weld zone during normal arc welding. However, as explained earlier and as detailed later, there is no welding arc, so there is no cathode or anode in the weld area. Therefore, since there is no arc and droplet transition, the chance that the metal filler picks up harmful elements from the atmosphere is greatly reduced. In many embodiments of the present invention, welding can be performed without using shielding such as shielding gas, but it is possible to remove steam or contaminants from the welding area using a gas flow over the weld. it can. That is, during welding, air, nitrogen, CO ₂ or other gases may be blown over the weld to remove contaminants from the weld area.

  In addition to being able to weld coatings at high speed, embodiments of the present invention can also be used to weld duplex stainless steels with a significantly reduced heat affected zone (“HAZ”). Since the duplex stainless steel is a high strength steel having both a ferrite microstructure and a martensite microstructure, the steel has high strength and good formability. Due to the properties of the duplex stainless steel, the strength of the duplex stainless steel is limited by the strength of the heat affected zone. The heat affected zone is an area around the welded joint (not including the metal filler), and is greatly heated by the welding process so that the microstructure is adversely changed by the arc welding process. In known arc welding processes, the heat affected zone is very large due to the size of the arc plasma and the large heat input to the welding area. Since the heat affected zone is very large, the heat affected zone becomes a part that limits the strength of the weld zone. As such, arc welding processes do not require the use of high-strength electrodes and, therefore, such joints are generally welded using a mild steel filler wire 140 (eg, ER70S-6 or ER70S-3 electrode). In addition, for this reason, designers must strategically place duplex welded joints outside high stress structures such as automobile frames, bumpers, engine cradle, and the like.

  As previously described, the use of the laser device 120 provides a high level of accuracy in forming the weld pool. With this accuracy, the heat affected zone surrounding the weld bead can be kept very small or the overall effect of the heat affected zone on the workpiece can be minimized. In fact, in some embodiments, the heat affected zone of the workpiece can be substantially eliminated. This is done by maintaining the focus of the laser beam 110 only on the part of the workpiece where the weld pool is formed. By significantly reducing the size of the heat affected zone, the strength of the base material is not compromised as much as when using an arc welding process. Therefore, the presence or location of the heat affected zone is not a limiting factor in the design of the welded structure. Embodiments of the present invention allow the use of higher strength filler wires. This is because the composition and strength of the workpiece, not the heat-affected zone, and the strength of the filler wire are driving factors for structural design. For example, embodiments of the present invention allow the use of electrodes with a yield strength of at least 80 ksi, such as ER80S-D2 type electrodes. Of course, this electrode is an example. Furthermore, since the overall heat input is less than in the case of arc welding, the cooling rate of the molten pool becomes faster. This means that the chemistry of the filler wire used can be made more efficient and can provide performance over existing wires.

  In addition, exemplary embodiments of the present invention can be used to weld titanium with significantly reduced shielding requirements. When welding titanium in an arc welding process, great care must be taken to form an acceptable weld. This is due to the high affinity of titanium to react with oxygen during the welding process. Titanium dioxide is formed by the reaction of titanium and oxygen, and if titanium dioxide is present in the weld pool, the strength and / or ductility of the weld joint can be significantly reduced. For this reason, when arc welding titanium, not only shields the arc from the atmosphere, but also a large amount of subsequent shielding gas to shield the melting pool from the atmosphere when cooling the subsequent melting pool. Need to provide. Due to the heat generated from arc welding, the weld pool becomes quite large and remains melted over a long period of time, requiring a large amount of shielding gas. Embodiments of the present invention significantly reduce the time the material is melting and cool quickly, thus reducing the need for extra shielding gas.

  As previously described, the laser beam 110 can be focused very carefully to significantly reduce the overall heat input to the weld area, thereby greatly reducing the size of the weld pool. Because the weld pool is smaller, the weld pool cools more quickly. Therefore, only shielding at the weld is necessary, and no subsequent shielding gas is necessary. Further, for the same reason as described above, when titanium is welded, the welding speed is improved while the sputtering coefficient is greatly reduced.

  7 and 7A show an open root type weld joint. Open root joints are commonly used when welding thick plates and pipes and commonly occur in remote locations and difficult environments. There are many known methods of welding open root joints, including shield metal arc welding (SMAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), flux cored arc welding ( FCAW), submerged arc welding (SAW), and self-shielded flux cored arc welding (FCAW-S). These welding processes have various disadvantages such as the need for shielding, speed limitations, and slag formation.

  Therefore, embodiments of the present invention significantly improve efficiency and speed when performing this type of welding. Specifically, the use of shielding gas can be eliminated or greatly reduced, and the generation of slag can be completely eliminated. Furthermore, it is possible to realize welding at high speed while minimizing spatter and porosity.

  7 and 7A illustrate an open root welded joint welded according to an exemplary embodiment of the present invention. Of course, embodiments of the present invention can be used to weld a wide variety of welded joints as well as lap joints or open root joints. In FIG. 7, a gap 705 is shown between the workpieces W1 / W2, and the workpieces W1 / W2 have inclined surfaces 701/703, respectively. As described above, in the embodiment of the present invention, a laser device 120 is used to form an accurate molten pool on the surface 701/703, and a filler wire (not shown) preheated as described above is used. It is welded in the molten pool.

  Indeed, exemplary embodiments of the present invention are not limited to directing one filler wire to each weld pool. Because the welding process described herein does not generate a welding arc, two or more filler wires can be directed to a single weld pool. By increasing the number of filler wires directed to a given weld pool, the overall welding rate of the welding process can be significantly increased without significantly increasing the heat input. Therefore, it is conceivable that an open route weld joint (such as the type shown in FIGS. 7 and 7A) can be filled in one welding pass.

  Also, as shown in FIG. 7, in some exemplary embodiments of the present invention, multiple laser beams 110 and 110A can be used to simultaneously melt two or more locations in a weld joint. This can be achieved in many ways. In the first embodiment shown in FIG. 7, a beam splitter 121 is used and connected to the laser device 120. The beam splitter 121 is known to have knowledge about laser devices, and detailed description thereof is omitted in this specification. Beam splitter 121 can split the beam from laser device 120 into two (or more) separate beams 110 / 110A and direct them to two different surfaces. In such embodiments, multiple surfaces can be illuminated simultaneously, providing additional accuracy and accuracy of welding. In other embodiments, each of the separate beams 110 and 110A can be formed by a separate laser device, and each beam is emitted from a dedicated device.

  In such embodiments, multiple laser devices can be used to modify various aspects of the welding operation to meet various welding needs. For example, beams generated by separate laser devices can have different energy densities, have different shapes, and / or have different cross-sectional areas at the weld joint. This flexibility allows aspects of the welding process to be modified and customized to meet the specific welding parameters required. Of course, this can be realized by using one laser device and the beam splitter 121. However, if one laser beam source is used, a part of flexibility can be limited. Further, since it is considered that an arbitrary number of lasers can be used as desired, the present invention is not limited to the configuration of one or two lasers.

  In a further embodiment, a beam scanning device can be used. Such devices are known in the art of laser or beam extraction and are used to scan the beam 110 in a pattern across the surface of the workpiece. By using such an apparatus, the workpiece 115 can be heated in a desired manner using the dwell time in addition to the scanning speed and pattern. Also, the output power of the energy source (eg, laser) can be adjusted as desired to form the desired weld pool. In addition, the optics used in the laser 120 can be optimized based on the desired operating and bonding parameters. For example, line optics and integration optics are used to generate a focused line beam for a wide range of welding or cladding operations, or integrators are used to generate a square / rectangular beam with a uniform power distribution. be able to.

  FIG. 7A illustrates another embodiment of the present invention. In this embodiment, one beam 110 is directed at the open root joint to melt the surfaces 701/703.

  Due to the accuracy of the laser beams 110 and 110A, the beam 110 / 110A can be focused away from the gap 705 and only on the surface 701/703. Therefore, melt-through (which can normally pass through the gap 705) can be controlled, and control of the rear weld bead (the weld bead on the bottom surface of the gap 705) is greatly improved.

  In each of FIGS. 7 and 7A, a gap 705 exists between the workpieces W1 and W2 and is filled with a weld bead 707. FIG. In the illustrated embodiment, the weld bead 707 is formed by a laser device (not shown). Thus, for example, during a welding operation, a first laser device (not shown) directs a first laser beam (not shown) to gap 705 to weld workpieces W1 and W2 with laser weld beads 707, On the other hand, the second laser device 120 directs at least one laser beam 110 / 110A onto the surface 701/703 to form a weld pool in which a filler wire (not shown) is deposited to complete the welding. The gap weld bead 707 can be formed only with a laser if the gap is sufficiently small, and can be formed using the laser and filler wire if the gap 705 requires a laser and filler wire. Specifically, a filler wire should be used because a metal filler may need to be added to properly fill the gap 705. The formation of this gap bead 705 is similar to that previously described with respect to the various exemplary embodiments of the present invention.

  It should be noted that the high intensity energy source, such as the laser device 120 described herein, should be of a type that has sufficient power to provide the energy density required for the desired welding operation. That is, the laser device 120 should have sufficient power to form and maintain a stable weld pool throughout the welding process and to reach the desired penetration. For example, in some applications, the laser should have the ability to form “keyholes” in the workpieces being welded. This means that the level of penetration is maintained as the laser moves along the workpiece while the laser has sufficient power to penetrate completely through the workpiece. The exemplary laser should have a power capability of 1-20 kW and may have a power capability of 5-20 kW. Higher power lasers can be used but can be very expensive. Of course, the beam splitter 121 or lasers can be used with other types of welded joints, and can also be used with lap joints such as those illustrated in FIGS. 6 and 6A.

  FIG. 7B shows another exemplary embodiment of the present invention. In this embodiment, a narrow groove and a deep open root joint are shown. When arc welding deep joints (depth greater than 1 inch), it may be difficult to weld the bottom of the joint if the groove gap G is narrow. This makes it difficult to effectively route shield gas into such deep grooves, and the narrow walls of the grooves can hinder the stability of arc welding. Since the workpiece is generally a steel material, the wall of the joint magnetically blocks the welding arc. Therefore, when using a general arc welding procedure, the groove gap G must be wide enough to keep the arc stable. However, the wider the groove, the more metal filler is required to complete the weld. Embodiments of the present invention do not require shielding gas and do not use welding arcs, so these problems are minimized. Thereby, the embodiment of the present invention can efficiently and effectively weld a deep and narrow groove. For example, in an exemplary embodiment of the invention where the thickness of the workpiece 115 is greater than 1 inch, the gap width G is in the range of 1.5 to 2 times the diameter of the filler wire 140 and the sidewall angle is 0. Within the range of 5-10 °. In the illustrated embodiment, the root path preparation gap RG of such a weld joint is 1 to 3 mm and the land is 1/16 to 1/4 inch. As a result, deep open root joints can be welded faster with much less filler than the normal arc welding process. Also, because the side of the present invention introduces less heat into the weld area, the contact tip 160 can be designed to be easier to route closer to the weld pool to avoid contact of the wire with the sidewall. That is, the contact chip 160 can be made small and configured as a thin structure insulating guide. In a further exemplary embodiment, a translation device or mechanism can be used to move the laser and wire across the width of the weld to weld both sides of the joint simultaneously.

  As shown in FIG. 8, a butt joint can be welded using an embodiment of the present invention. Although a flash butt joint is shown in FIG. 8, it is conceivable that a bad joint having v-shaped cutout grooves on the top and bottom surfaces of the weld joint can also be welded. In the embodiment shown in FIG. 8, two laser devices 120 and 120A are shown on each side of the weld joint, and the weld pools 801 and 803 are formed by themselves. As in FIGS. 7 and 7A, the heated filler wire is not shown because it follows the laser beam 110 / 110A.

  When welding butt joints using known arc technology, significant problems with “magnetic blow” can occur. In “magnetic blowing”, the magnetic fields generated by the welding arc interfere with each other and move each other irregularly. Also, when two or more arc welding systems are used to perform welding on the same weld joint, there is a major problem caused by interference of each welding current. In addition, the depth of penetration of the arc welding process (partially due to high heat input) limits the thickness of the workpiece that can be welded with an arc on either side of the weld joint. . That is, such welding cannot be performed on a thin workpiece.

  When welding is performed using the embodiment of the present invention, these problems are solved. Since no welding arc is used, there is no problem of magnetic blow interference or welding current interference. Also, finer workpieces can be welded simultaneously on both sides of the weld joint, with precise control of the depth of penetration and heat input made possible by the use of a laser.

  A further exemplary embodiment of the present invention is shown in FIG. In this embodiment, two laser beams 110 and 110A are used in line with each other to form a unique weld profile. In the illustrated embodiment, a first beam 110 (emitted from the first laser device 120) is used to form a first portion of a weld pool 901 having a first cross-sectional area and depth, while ( A second beam 110A (emitted from a second laser device (not shown)) is used to form a second portion of weld pool 903 having a second cross-sectional area and depth different from the first. This embodiment can be used where it is desirable to have a portion of the weld bead where the penetration depth is deeper than the rest of the weld bead. For example, as shown in FIG. 9, the weld pool 901 is formed to be deeper and narrower than the weld pool 903 (the weld pool 903 is wider and shallower than the weld pool 901). Such an embodiment can be used when a deep penetration level is required that is undesirable for the weld joint as a whole (where the workpieces meet).

  In a further exemplary embodiment of the present invention, the first weld pool 903 can be a weld pool that forms a weld for a joint. This first weld pool / joint is formed using a first laser 120 and filler wire (not shown) and is formed to an appropriate penetration depth. After the formation of this weld joint, a second laser (not shown) that emits the second laser beam 110A passes over the joint and forms a second weld pool 903 having a different profile. This second weld pool 903 is used to weld a certain type of overlay described in the previous embodiment. This build-up is welded using a second filler wire that has a different chemical structure from the first filler wire. For example, embodiments of the present invention can be used to install a corrosion-resistant buildup layer on a joint just after or just after welding a welded joint. This welding operation can also be accomplished using a single laser device 120, in which case the beam 110 has a first beam shape / density and a second beam shape / density to provide the desired weld pool profile. Oscillated between. Therefore, it is not necessary to use a plurality of laser devices.

  As previously described, the corrosion resistant coating (eg, galvanizing) on the workpiece is removed during the welding process. However, it may be desirable to recoat the welded joint for corrosion resistance. Therefore, it is possible to add a corrosion-resistant buildup 903 such as a buildup layer on the joint 901 using the second beam 110 </ b> A and a laser.

  Due to the various advantages of the present invention, dissimilar metals can also be easily joined by welding operations. It is difficult to join dissimilar metals by arc welding process. This is because the chemical structure required for dissimilar materials and fillers can lead to cracks and poor quality welds. This is especially true when trying to arc weld aluminum and steel with very different melting temperatures or when trying to weld stainless steel to mild steel because of their different chemical structures. However, such problems are mitigated by using embodiments of the present invention.

  FIG. 10 shows an exemplary embodiment of the present invention. Although a V-shaped joint is shown, the present invention is not limited in this respect. FIG. 10 shows two dissimilar metals joined by a welded joint 1000. In this example, the two dissimilar metals are aluminum and steel. In this exemplary embodiment, two different laser sources 1010 and 1020 are used. However, all embodiments require two laser devices because one device can be oscillated to provide the energy needed to melt two different materials (which will be further described below). Do not mean. Laser 1010 emits beam 1011 directed at the steel workpiece, and laser 1020 emits beam 1021 at the aluminum workpiece. Since each workpiece is made of a different metal or alloy, their melting temperatures are different. For this reason, the laser beams 1011/1021 have different energy densities in the weld pools 1012 and 1022, respectively. Because the energy density is different, each of the weld pools 1012 and 1022 can be maintained at an appropriate size and depth. This also prevents excessive penetration and heat input in the lower melting temperature workpiece, such as an aluminum workpiece. In some embodiments, at least by the weld joint, it is not necessary to have two separate weld pools (as shown in FIG. 10), but rather one work pool can be formed by both workpieces, in which case The melted part of each workpiece forms one weld pool. Also, if the workpieces have different chemical structures but have similar melting temperatures, one workpiece can be used to simultaneously combine both workpieces with the understanding that one workpiece will melt more than the other. Can be irradiated. Also, as briefly described above, both workpieces can be irradiated using a single energy source (such as laser device 120). For example, the laser device 120 uses a first beam shape and / or energy density to melt the first workpiece and then oscillates / changes to the second beam shape and / or energy density to produce the second workpiece. Pieces can be melted. Oscillation and modification of the beam characteristics should be made at a sufficient rate so that both workpieces are properly melted so that the weld pool is maintained stable and consistent during the welding process. In another beam embodiment, a beam 110 can be used that is shaped to provide more heat input to the other workpiece than one workpiece so that each workpiece is sufficiently melted. In such embodiments, the energy density of the beam is uniform with respect to the beam cross-section. For example, the beam 110 may have a trapezoidal or triangular shape such that the beam shape results in less overall heat input to one workpiece than to the other workpiece. Alternatively, in other embodiments, a beam 110 with non-uniform energy distribution in its cross section can be used. For example, the beam 110 has a rectangular shape (so that both workpieces can be affected), but the first region of the beam has a first energy density and the second region of the beam 110 has a first energy density. Each region has a second energy density different from one region, and each region can properly melt each workpiece. As an example, the beam 110 has a first region that is high in energy density to melt the steel workpiece, while the second region is low in energy density to melt the aluminum workpiece.

  FIG. 10 shows two filler wires 1030 and 1030A directed to weld pools 1012 and 1022, respectively. Although two filler wires are used in the embodiment shown in FIG. 10, the present invention is not limited in that respect. As described above in connection with other embodiments, only one filler wire can be used depending on the desired welding parameters, such as the desired bead shape and deposition rate, and more than two wires can be used. It can be used. When using a single wire, the wire may be directed to a common weld pool (formed from the melted portions of both workpieces) or to only one of the melted portions to be integrated into the weld joint. it can. Thus, for example, in the embodiment shown in FIG. 10, the wire can be directed to the melted portion 1022, which is then combined with the melted portion 1012 to form a weld joint. Of course, if a single wire is used, it must be heated to a temperature so that the wire melts in the portion 1022/1012 where the wire is immersed.

  Since dissimilar metals are bonded, the chemical structure of the filler wire should be selected so that the wire can be sufficiently bonded to the metal to be bonded. Furthermore, the filler wire composition should be selected so that the filler wire has a suitable melting temperature that allows the filler wire to melt and be consumed in the lower temperature weld pool. Indeed, it is conceivable that the chemical structure of the filler wires may be different in order to obtain the appropriate welding chemistry. This is especially true when two different workpieces have a material composition that results in minimal mixing between the materials. In FIG. 10, the weld pool having the lower temperature is the aluminum weld pool 1012, so the filler wire 1030 (A) is prepared to melt at the same temperature so that it is easily consumed in the weld pool 1012. . In the above example using aluminum and steel workpieces, the filler wire can be a silicon bronze, nickel aluminum bronze or aluminum bronze based wire having a melting temperature similar to that of the workpiece. Of course, it is believed that the filler wire composition should be chosen to match the desired mechanical and welding performance characteristics while at the same time providing melting characteristics similar to at least one of the workpieces being welded. It is done.

  11A-11C illustrate various embodiments of contact tips 160 that can be used. FIG. 11A shows a contact tip 160 that is very similar in construction and operation to a typical arc welding contact tip. During hot wire welding as described herein, the heating current is directed from the power source 170 to the contact tip 160 and passed from the contact tip 160 to the wire 140. The current then passes through the wire and is directed to the workpiece via contact between the wire 140 and the workpiece W. This current flow heats the wire 140 as described herein. Of course, the power source 170 is not directly coupled to the contact tip as shown, but can be coupled to a wire feeder 150 that directs current to the contact tip 160. FIG. 11B shows another embodiment of the present invention. In this embodiment, the contact chip 160 is composed of two components 160 and 160 ', and the negative electrode of the power source 170 is connected to the second component 160'. In such an embodiment, the heating current flows from the first contact tip component 160 to the wire 140 and then to the second contact tip component 160 '. Current flow through the wire 140 between components 160 and 160 'causes the wire to heat as described herein. FIG. 11C shows another exemplary embodiment. In this embodiment, the contact tip 160 includes an induction coil 1110 that heats the contact tip 160 and the wire 140 by induction heating. In such an embodiment, the induction coil 1110 may be formed integrally with the contact tip 160 or may be wound around the surface of the contact tip 160. Of course, other configurations for the contact tip 160 can be used as long as the contact tip can supply the wire 140 with the necessary heating current / power so that the wire can obtain the desired temperature for the welding operation.

  The operation of the exemplary embodiment of the present invention will be described. As previously described, embodiments of the present invention use both a high intensity energy source and a power source to heat the filler wire. Each aspect of this process will be described in turn. It should be noted that the following descriptions and explanations are not intended to replace or replace any of the descriptions previously described in connection with the above-described embodiment of the overlay, and are not intended to be a description of welding or joining applications. It is intended to be captured. The previous description of the overlay operation is also incorporated for joining and welding.

  An exemplary embodiment for joining / welding may be similar to that shown in FIG. As previously described, a hot wire power supply 170 is provided that provides a heating current to the filler wire 140. Current flows from contact tip 160 (which can be of any known configuration) to wire 140 and to the workpiece. This resistance heating current reaches the wire 140 between the contact tip 160 and the workpiece at or near the melting temperature of the filler wire 140 being used. Of course, the melting temperature of the filler wire 140 varies depending on the size and chemical structure of the wire 140. Thus, the desired temperature of the filler wire during welding varies with the wire 140. As described further below, the desired working temperature of the filler wire can be data that is input to the welding system such that the desired wire temperature is maintained during welding. In any case, the temperature of the wire should be such that the wire is consumed in the weld pool during the welding operation. In the illustrated embodiment, at least a portion of the filler wire 140 is solid when the wire enters the weld pool. For example, at least 30% of the filler wire is solid when the filler wire enters the weld pool.

  In an exemplary embodiment of the invention, hot wire power supply 170 provides a current that maintains at least a portion of the filler wire at a temperature that is greater than or equal to 75% of its melting temperature. For example, when a mild steel filler wire 140 is used, the wire temperature before entering the weld pool is about 1600 degrees Fahrenheit, while the wire melting temperature is about 2000 degrees Fahrenheit. Of course, it will be appreciated that each melting temperature and desired working temperature will vary depending at least on the filler wire alloy, composition, diameter and feed rate. In other exemplary embodiments, the power source 170 maintains a portion of the filler wire at a temperature that is 90% or more of its melting temperature. In a further exemplary embodiment, a portion of the wire is maintained at a temperature that is greater than 95% of its melting temperature. In the illustrated embodiment, the wire 140 has a temperature gradient from the time when the heating current is applied to the wire 140 and the weld pool, and the temperature in the weld pool is higher than the temperature at the input time of the heating current. In order to promote efficient melting of the wire 140, it is desirable that the temperature of the wire 140 be highest at or near the point where the wire enters the weld pool. Therefore, the above temperature ratio is measured on the wire at or near the point where the wire enters the weld pool. By maintaining the filler wire 140 at or near its melting temperature, the wire 140 is easily melted or consumed in the weld pool formed by the heat source / laser 120. That is, the wire 140 is at a temperature that does not cause significant cooling of the weld pool when the wire 140 contacts the weld pool. Since the temperature of the wire 140 is high, the wire quickly melts when it comes into contact with the weld pool. It is desirable to have a wire temperature that prevents the wire from reaching the bottom in the weld pool (in contact with the unmelted portion of the weld pool). Such contact adversely affects the quality of the weld.

  As previously described, in some exemplary embodiments, complete melting of the wire 140 can only be facilitated by the wire 140 entering the weld pool. However, in other exemplary embodiments, the wire 140 can be completely melted by a combination of a weld pool and a laser beam 110 that affects a portion of the wire 140. In yet another embodiment of the present invention, the laser beam 110 can assist in heating / melting the wire 140 by the laser beam 110 contributing to the heating of the wire 140. However, since many filler wires 140 are made of a material that can have reflectivity, when a reflective laser is used, the wire 140 is heated to a temperature at which the reflectivity of the surface is reduced, and the beam 110 is heated. Should be able to contribute to heating / melting of the wire 140. In an exemplary embodiment of this configuration, wire 140 and beam 110 intersect at the point where wire 140 enters the weld pool.

  As previously described in connection with FIG. 1, power supply 170 and controller 195 control the heating current to wire 140 so that wire 140 maintains contact with the workpiece and no arc is generated during welding. To do. Contrary to arc welding techniques, when welding is performed using embodiments of the present invention, the presence of the arc can cause significant defects in the weld. Thus, in some embodiments (similar to those previously described), the voltage between the wire 140 and the weld pool is indicated (indicating that the wire is shorted or in contact with the workpiece / weld pool). ) Should be maintained at or near 0 volts.

  However, other exemplary embodiments of the present invention can provide a level of current such that a voltage level greater than 0 volts can be obtained without generating an arc. By utilizing a higher current value, the electrode 140 can be maintained at a higher level of temperature and close to the melting temperature of the electrode. Thereby, a welding process can be advanced faster. In the exemplary embodiment of the present invention, the power supply 170 observes the voltage, and when the voltage reaches or approaches a voltage value that is slightly above 0 volts, the power supply 170 does not form an arc. Stop the flow of current to the. The threshold level of voltage typically varies, at least in part, depending on the type of welding electrode 140 used. For example, in some exemplary embodiments of the present invention, the voltage threshold level is 6 volts or less. In another exemplary embodiment, the threshold level is 9 volts or less. In a further exemplary embodiment, the threshold level is 14 volts or less, and in an additional exemplary embodiment, the threshold level is 16 volts or less. For example, if mild steel filler wire is used, the threshold voltage level will be of the low type, while if the filler wire is for stainless steel, the weld can handle higher voltages before the arc is formed.

  In a further exemplary embodiment, rather than maintaining the voltage level below a threshold as described above, the voltage is maintained in the working range. In such embodiments, the filler wire is greater than the minimum amount that can ensure a sufficiently high current to maintain at or near its melting temperature and above the voltage level at which the welding arc is formed. It is desirable to maintain the voltage at a small level. For example, the voltage can be maintained at 1-16 volts. In a further exemplary embodiment, the voltage is maintained at 6-9 volts. In other examples, the voltage can be maintained at 12-16 volts. Of course, the desired working range is selected in the welding operation such that the range (or threshold) used in the welding operation is selected based at least in part on the filler wire used or the properties of the filler wire used. Affected by. In using such a range, the lower limit of the range is set to a voltage at which the filler wire is sufficiently consumed in the weld pool, and the upper limit of the range is set to a voltage at which arc formation is prevented.

  As previously described, when the voltage exceeds the desired voltage threshold, the heating current is turned off by the power supply 170 so that no arc is formed. This aspect of the present invention is further described below.

  In many of the embodiments described above, the power supply 170 includes circuitry used to observe and maintain the voltage as described above. The construction of such types of circuits is known to those skilled in the art. Conventionally, however, such circuits have been used to maintain the voltage above a predetermined threshold for arc welding.

  In a further exemplary embodiment, the heating current can be observed and / or adjusted by the power source 170. This can alternatively be done in addition to observing certain levels of voltage, power or voltage / ampere characteristics. That is, the current is maintained at a desired level that is such that the wire 140 is maintained at an appropriate temperature so that it is properly consumed in the weld pool, but less than the arc generation current level. For example, in such an embodiment, the voltage and / or current is observed such that one or both are within a particular range or below a desired threshold. The power supply then regulates the current supplied so that no arc is formed and the desired operating parameters are maintained.

  In a further exemplary embodiment of the present invention, the heating power (V × I) can also be observed and adjusted by the power source 170. Specifically, in such embodiments, the voltage and current for the heating power is observed to be maintained at a desired level or within a desired range. Thus, the power supply can not only adjust the voltage or current to the wire, but can adjust both the current and voltage. Such an embodiment may improve control over the welding system. In such an embodiment, the heating power to the wire is at or above the upper threshold level (similar to that described above in relation to voltage) such that the power is maintained below the threshold level or within a desired range. Can be set within a wide range of work. Again, the threshold or range setting is based on the characteristics of the filler wire and the welding performed, and can be based at least in part on the selected filler wire. For example, assume that the optimum power setting for a 0.045 "diameter mild steel electrode is determined to be 1950-2050 watts. The power supply regulates the voltage and current so that the power remains within this operating range. Similarly, if the power threshold is set at 2000 watts, the power supply adjusts the voltage and current so that the power level is not above this threshold but is near the threshold.

  In a further exemplary embodiment of the present invention, power supply 170 includes circuitry that observes the rate of change of heating voltage (dv / dt), current (di / dv) and / or power (dp / dt). Such circuits are commonly referred to as prediction circuits, and their general configuration is well known. In such embodiments, the rate of change of voltage, current and / or power is observed such that the heating current to wire 140 is stopped when the rate of change exceeds a predetermined threshold.

  In an exemplary embodiment of the invention, a change in resistance (dr / dt) is also observed. In such embodiments, resistance between the contact tip and the weld pool in the wire is observed. As the wire is heated during welding, the wire begins to bend down and tends to form an arc. During that period, the resistance in the wire increases rapidly. When this increase is detected, the output of the power supply is stopped as previously described so that no arc is formed. Embodiments adjust the voltage, current, or both so that the resistance in the wire is maintained at a desired level.

  In a further exemplary embodiment of the present invention, the power supply 170 does not stop the heating current when a threshold level is detected, but reduces the heating current to a non-arcing level. Such a level may be a background current level at which no arc is generated when the wire is away from the weld pool. For example, an exemplary embodiment of the present invention can have a non-arc generated current level of 50 amps. In that case, if the generation of an arc is detected or predicted or the upper threshold (described above) has been reached, the power source 170 is either a predetermined period (eg 1-10 ms) or the detected voltage, The heating current is reduced from its operating level to a non-arcing level until the current, power and / or resistance falls below the upper threshold. This non-arcing threshold may be a voltage level, a current level, a resistance level, and / or a power level. In such an embodiment, the operating level of the heating current can be quickly restored even though the current output is maintained at a low level during the arc generation event.

  In another exemplary embodiment of the present invention, the output of the power source 170 is controlled so that no arc is substantially generated during the welding operation. In some exemplary welding operations, the power source can be controlled such that an arc is not substantially generated between the filler wire 140 and the weld pool. It is generally known that the arc is formed in the physical gap between the distal end of the filler wire 140 and the weld pool. As previously described, exemplary embodiments of the present invention prevent arc generation by maintaining contact between filler wire 140 and the weld pool. However, in some exemplary embodiments, the quality of the weld is not compromised by the presence of very little arc. That is, in some exemplary welding operations, the formation of very few arcs in a short period of time does not result in a level of heat input that impairs the weld quality. In such an embodiment, the welding system and power source are controlled and operated as described herein in connection with completely preventing arcs, but the power source 170 generates some arc. The arc is controlled to be negligible. In some exemplary embodiments, power supply 170 is operated such that the duration of the arc formed is less than 10 ms. In other exemplary embodiments, the arc duration is less than 1 ms, and in another exemplary embodiment, the arc duration is less than 300 μs. In such embodiments, the presence of such an arc does not impair weld quality. This is because such arcs do not provide substantial heat input to the weld or cause significant spatter or porosity. Thus, in such an embodiment, the power source 170 is controlled to be negligible over time so that arcs are generated but weld quality is not compromised. The same control logic and components described herein with respect to other embodiments can be used in these illustrative embodiments. However, the power supply 170 can use detection of arc generation as an upper threshold rather than a threshold (current, power, voltage, resistance) below a predetermined or predicted arc generation point. Such an embodiment allows welding operations to be performed near that limit.

  Since it is desirable that the filler wire 40 is always in a short-circuit state (a state where the filler wire 40 is always in contact with the weld pool), the current tends to decay at a moderate rate. This is due to the inductance present in the power supply, welding cable and workpiece. In some applications, it may be necessary to attenuate the current at a faster rate so that the current in the wire decreases at a faster rate. In general, the faster the current can be reduced, the better control over the bonding method is obtained. In an exemplary embodiment of the present invention, the ramp down time to decrease the current after it is detected that the threshold has been reached or exceeded is 1 millisecond. In another exemplary embodiment of the present invention, the current ramp-down time is 300 microseconds or less. In another exemplary embodiment, the ramp down time is 100-300 microseconds.

  In the illustrated embodiment, a ramp-down circuit is introduced in the power supply 170 to obtain such ramp-down time. The ramp down circuit helps to reduce the ramp down time if an arc is predicted or detected. For example, if an arc is detected or predicted, the ramp down circuit is opened and resistance is introduced into such a circuit. For example, such a resistor may be of the type that reduces the current flow to less than 50 amps in 50 microseconds. A simplified example of such a circuit is shown in FIG. The circuit 1800 includes a resistor 1801 and a switch 1803. Resistor 1801 and switch 1803 are arranged in the welding circuit so that switch 1803 is closed when the power supply is activated and supplying current. However, when the power supply stops supplying power (to prevent arc generation or when an arc is detected), the switch opens and causes an induced current to flow through resistor 1801. Resistor 1801 greatly increases the resistance of the circuit and reduces the current at a faster pace. Such circuit types are generally known in the welding industry and include the Powerwave® welding power source from Lincoln Electric (Cleveland, Ohio) that incorporates surface tension transfer technology (“STT”). Can see. The STT technique is widely described in Patent Document 1, Patent Document 2, Patent Document 3 and Patent Document 4, and these patent documents are entirely incorporated in the present application by reference. Of course, although these patent documents generally describe the generation and maintenance of arcs using the disclosed circuit, those skilled in the art should ensure that such systems do not generate arcs. Easy to adapt.

  The above description can be further understood with reference to FIG. 12, which shows an exemplary welding system (note that the laser system is not shown for clarity). Shown is a system 1200 having a hot wire power supply 1210 (which can be of the same type as 170 shown in FIG. 1). The power source 1210 can be of a known welding power source configuration such as an inverter type power source. Since the design, operation and configuration of such a power supply are known, a detailed description thereof will be omitted herein. The power supply 1210 includes a user input unit 1220. User input 1220 allows a user to input data including, but not limited to, wire feed speed, wire type, wire diameter, desired power level, desired wire temperature, voltage and / or current level. Of course, other input parameters can be used as needed. User interface 1220 is coupled to CPU / controller 1230. The CPU / controller 1230 receives user input data and uses the information to generate the required operation set values or ranges for the power module 1250. The power module 1250 can be of any known type or configuration including an inverter or transformer type module.

  The CPU / controller 1230 can determine the desired operating parameters in a variety of ways, including using a look-up table. In such an embodiment, the CPU / controller 1230 uses input data such as wire feed speed, wire diameter, and wire type to generate a desired current for output (to properly heat the wire 140). Determine the level and threshold voltage or power level (or acceptable operating range of voltage or power). This is because the current required to heat the wire 140 to the appropriate temperature is based at least on the input parameters. That is, since the melting temperature of the aluminum wire 140 is lower than that of the mild steel electrode, less current / power is required to melt the wire 140. In addition, the smaller diameter wire 140 requires less current / power than the larger diameter electrode. Also, as the wire feed rate increases (and hence the welding rate), the current / power level required to melt the wire becomes higher.

  Similarly, input data is used by CPU / controller 1230 to determine voltage / power thresholds and / or ranges (eg, power, current and / or voltage) for operations such that arc generation is avoided. Is done. For example, the voltage range setting for a 0.045 inch diameter mild steel electrode is 6-9 volts, and the power module 1250 is driven to maintain a voltage in the range of 6-9 volts. In such an embodiment, the current, voltage and / or power is maintained at a minimum of 6 volts ensuring that the current / power is high enough to properly heat the electrodes, no arc is generated and the wire 140 is It is driven so that the voltage is maintained at 9 volts or less so as not to exceed the melting temperature. Of course, the CPU / controller 1230 may set other set value parameters such as the rate of change of voltage, current, power or resistance as required.

  As shown, the positive electrode 1221 of the power supply 1210 is connected to the contact chip 160 of the hot wire system, and the negative electrode of the power supply is connected to the workpiece W. Therefore, the heating current is supplied to the wire 140 through the positive electrode 1221 and returns through the negative electrode 1222. Such a configuration is generally known.

  Of course, in other exemplary embodiments, the negative electrode 1222 can also be coupled to the contact tip 160. Since resistance heating can be used to heat the wire 140, the contact chip can connect the positive electrode 1221 and the negative electrode 1222 to the contact chip 160 to heat the wire 140 (as shown in FIG. 11). Can be. For example, the contact tip 160 may have a dual configuration (as shown in FIG. 11B) or an induction coil (as shown in FIG. 11C).

  A feedback detection lead 1223 is also coupled to the power source 1210. This feedback sensing lead can observe the voltage and send the detected voltage to the voltage detection circuit 1240. The voltage detection circuit 1240 communicates the detected voltage and / or the rate of change of the detected voltage to the CPU / controller 1230, and the CPU / controller 1230 controls the operation of the module 1250 accordingly. For example, if the detected voltage is lower than the desired operating range, the CPU / controller 1230 causes the module 1250 to output its output (current, voltage and / or power) until the detected voltage falls within the desired operating range. Instruct to increase. Similarly, if the detected voltage is greater than or equal to the desired threshold, the CPU / controller 1230 instructs the module 1250 to stop current flow to the contact tip 160 so that no arc is generated. When the voltage drops below the desired threshold, the CPU / controller 1230 instructs the module 1250 to supply current and / or voltage to continue the welding process. Of course, the CPU / controller 1230 can also instruct the module 1250 to maintain or supply the desired power level.

  Note that the detection circuit 1240 and the CPU / controller 1230 can have the same configuration and operation as the controller 195 shown in FIG. In an exemplary embodiment of the invention, the sampling / detection rate is at least 10 KHz. In another exemplary embodiment, the detection / sampling rate range is 100-200 KHz.

  13A to 13C show exemplary current waveforms and voltage waveforms used in the embodiment of the present invention. Each of these waveforms will be described in turn. FIG. 13A shows the voltage and current waveforms for an embodiment in which the filler wire 140 contacts the weld pool after the power output is turned on again after an arc detection event. As shown, the output voltage of the power supply was at a certain operating level below a predetermined threshold (9 volts), but then raised to this threshold during welding. The operating level may be a predetermined level based on various input parameters (described above), or may be a set operating voltage, current and / or power level. This level of operation is the desired power source 170 output for a given welding operation and is intended to provide the filler wire 140 with a desired heating signal. During welding, events can occur that lead to arc generation. In FIG. 13A, such an event causes a voltage rise, causing the voltage to rise to point A. At point A, the power / control circuit hits a 9 volt threshold (which could be a predetermined upper threshold that is lower than the arc detection point or just the arc generation point), stops the output of the power source, and points to current and voltage. Reduce to a lower level in B. The slope of the current drop can be controlled by including a ramp-down circuit (described herein) that helps to quickly reduce the current resultant from the system inductance. The current or voltage level at point B may be predetermined or may be reached after a predetermined period. For example, in some embodiments, an upper threshold for voltage (or current or power) is set for welding as well as a lower non-arc generation level. This lower limit level is the lower voltage, current, or power level that ensures that no arc is generated and no arc is formed when the power is turned on again. By having such a lower level, the power supply can be quickly turned on again to prevent arcing. For example, if the power setpoint for welding is set to 2000 watts and the voltage threshold is 11 volts, this lower limit power setting can be set to 500 watts. Thus, when the upper voltage threshold (which can be a current or power threshold depending on the embodiment) is reached, the output is dropped to 500 watts (this lower threshold can also be the lower current or voltage setting or both). . Alternatively, instead of setting the detection lower limit, current supply can be started after a period set using the timing circuit. In an exemplary embodiment of the invention, such a period may be between 500 and 1000 ms. In FIG. 13A, point C represents the point at which output is again applied to wire 140. Note that the delay shown between points B and C is the result of intentional delay or simply the result of system delay. At point C, current is supplied again to heat the filler wire. However, since the filler wire is not yet in contact with the weld pool, the voltage increases while the current does not increase. At point D, the wire contacts the weld pool and the voltage and current return to the desired operating level. As shown, the voltage may exceed the upper threshold before touching at point D. It can occur when the power supply has an OCV level that is higher than the operating threshold. For example, this high OCV level may be an upper limit set at the power supply as a result of the design or manufacture of the power supply.

  FIG. 13B is similar to that previously described, except that the filler wire 140 is in contact with the weld pool when the power output is increased. In such a situation, the wire did not leave the weld pool or the wire was in contact with the weld pool before point C. FIG. 13B shows points C and D together. This is because the wire is in contact with the weld pool when the output is turned on again. Thus, both current and voltage are increased to the desired operating setting at point E.

  FIG. 13C shows that there is no or little delay between when the output is turned off (point A) and when it is turned on again (point B), and the wire is at some point before point B. The embodiment in contact with the weld pool is shown. The waveform shown is for the above embodiment where the lower limit is set so that when the lower limit is reached (regardless of current, power or voltage), the output is turned on again without delay or with a slight delay. Can be used. This lower limit can be set using the same or similar parameters as the operation upper limit threshold or range described in this specification. For example, this lower threshold can be set based on the wire composition, diameter, feed rate, or various other parameters described herein. Such embodiments can minimize the delay in returning to the desired operating set point for welding and can minimize necking that may occur in the wire. Minimizing necking helps to minimize the possibility of arcing.

  FIG. 14 shows yet another exemplary embodiment of the present invention. FIG. 14 shows the same thing as the embodiment shown in FIG. However, certain components and connections are not shown for clarity. FIG. 14 shows a system 1400 in which a thermal sensor 1410 is used to observe the temperature of the wire 140. The thermal sensor 1410 may be of any known type that can detect the temperature of the wire 140. Sensor 1410 can contact wire 140 or can be coupled to contact tip 160 to detect the temperature of the wire. In a further exemplary embodiment of the present invention, the sensor 1410 is of the type that uses a laser or infrared beam and can detect the temperature of a small object, such as the diameter of a filler wire, without contacting the wire 140. In such an embodiment, the sensor 1410 is arranged such that the temperature of the wire 140 can be detected at some point between the protrusion of the wire 140, that is, the end of the contact tip 160 and the weld pool. The sensor 1410 should be arranged so that the sensor 1410 for the wire 140 does not sense the temperature of the weld pool.

  Sensor 1410 is coupled to detection / control unit 195 (described in connection with FIG. 1) so that temperature feedback information can be provided to power supply 170 and / or laser power supply 130 so that control of system 1400 can be optimized. Has been. For example, the power or current output of the power supply 170 can be adjusted based at least on feedback from the sensor 1410. That is, in an embodiment of the present invention, the user inputs a desired temperature setting (for a given weld and / or wire 140) or the sensing / control unit receives other user input data (wire feed speed, electrode type, etc. ) And a sensing / control unit 195 can control at least the power supply 170 to maintain the desired temperature.

  In such embodiments, heating of the wire 140 is possible, which can occur by the laser beam 110 affecting the wire 140 before the wire enters the weld pool. In embodiments of the present invention, the temperature of the wire 140 can only be controlled by controlling the current in the wire 140 via the power source 170. However, in other embodiments, at least a portion of the heating of the wire 140 may be due to the laser beam 110 acting on at least a portion of the wire 140. Therefore, only the current or power from the power source 170 may not represent the temperature of the wire 140. Therefore, the sensor 1410 can be used to assist in adjusting the temperature of the wire 140 through the control of the power source 170 and / or the laser power source 130.

  In a further exemplary embodiment (also shown in FIG. 14), a temperature sensor 1420 is configured to sense the temperature of the weld pool. In this embodiment, the temperature of the weld pool is also coupled to the detection / control unit 195. However, in other exemplary embodiments, sensor 1420 can be directly coupled to laser power supply 130. Feedback from sensor 1420 can be used to control the output from laser power supply 130 / laser 120. That is, the energy density of the laser beam 110 can be changed so that a desired weld pool temperature can be obtained.

  In a further exemplary embodiment of the present invention, the sensor 1420 can be pointed to a region adjacent to the weld pool of the workpiece, rather than pointing to the weld pool. Specifically, it may be desirable to minimize heat input to the workpiece adjacent to the weld. The sensor 1420 can be installed to observe this temperature sensitive region so that the threshold temperature does not exceed the vicinity of the weld. For example, the sensor 1420 can observe the workpiece temperature and reduce the energy density of the beam 110 based on the detected temperature. Such a configuration can prevent the heat input near the weld bead from exceeding a desired threshold. Such an embodiment can be used in precision welding operations where heat input to the workpiece is critical.

  In another exemplary embodiment of the present invention, the sensing / control unit 195 is coupled to a feed force detection unit coupled to a wire feed mechanism (not shown, but see 150 in FIG. 1). be able to. The feed force detection unit is known and detects the feed force applied to the wire 140 when the wire 140 is fed to the workpiece 115. For example, such a detection unit can observe the torque applied by the wire feed motor of the wire feeder 150. As the wire 140 passes through the molten pool without being completely melted, the wire 140 will come into contact with the solid portion of the workpiece. As the motor attempts to maintain the set feed rate, such contact causes an increase in feed force. This increase in force / torque can be detected and transmitted to the controller 195. The controller 195 uses this information to adjust the voltage, current, and / or power to the wire 140 to ensure proper melting of the wire 140 in the melt pool.

  It should be noted that in some exemplary embodiments of the present invention, the wire may not be continuously fed into the weld pool, but may be intermittently fed based on the desired weld profile. Specifically, the variety of various embodiments of the present invention allows either an operator or control unit 195 to start and stop the delivery of wire 140 to the melt pool as desired. For example, some weld joints require the use of metal fillers (wires 140), but other parts of the same joint or the same workpiece have a variety of complex weld profiles and shapes that do not require the use of metal fillers. There are many. Therefore, in the first part of the welding, the control unit 195 operates only the laser 120 so that the first part of the joint is laser welded, but the welding operation (requires the use of a metal filler) When the second portion of the weld joint is reached, the controller 195 causes the power supply 170 and the wire feeder 150 to begin welding the wire 140 in the weld pool. When the welding operation reaches the end of the second portion, the welding of the wire 140 can be stopped. This allows for the formation of continuous welds that differ greatly in profile from one part to another. Such a capability allows the workpieces to be welded in a single welding operation as opposed to having many individual welding operations. Of course, many changes can be made. For example, the weld has three or more different parts that require weld profiles having different shapes, depths and filler requirements, and the use of laser and wire 140 may be different at each weld part. Further, additional wires may be added or removed as necessary. That is, the first weld portion only requires laser welding, while the second portion only requires the use of one filler wire 140 and the last portion of the weld uses two or more filler wires. Need. The controller 195 can be configured to control various components of the system so that various welding profiles can be obtained in a continuous welding operation such that a continuous weld bead is formed in a single weld pass.

  FIG. 15 shows a typical weld pool P when welding according to an exemplary embodiment of the present invention. As described above, the laser beam 110 forms a weld pool P on the surface of the workpiece W. The weld pool has a length L, which is a function of the energy density, shape and motion of the beam 110. In the exemplary embodiment of the present invention, the beam 110 is directed to the weld pool P at a distance Z from the rear end of the weld pool. In such an embodiment, the high intensity energy source (eg, laser 120) may be achieved by the wire 140 being in contact with the weld pool, rather than the energy source 120 melting the wire 140. Therefore, the energy of itself does not directly act on the filler wire 140. Generally, the rear end of the molten pool P is defined as the point at which the weld pool ends and solidification of the formed weld bead WB begins. In the embodiment of the present invention, the distance Z is 50% of the length L of the weld pool P. In a further exemplary embodiment, the distance Z is 40-75% of the length L of the weld pool P.

  As shown in FIG. 15, the filler wire 140 affects the weld pool P behind the beam 110 (in the direction of movement of the weld). As shown, the wire 140 affects the weld pool P as a distance X before the rear end of the weld pool P. In the illustrated embodiment, the distance X is 20-60% of the length of the weld pool P. In another exemplary embodiment, the distance X is 30-45% of the length L of the weld pool P. In other exemplary embodiments, wire 140 and beam 110 intersect at the surface of weld pool P or at a point above weld pool P such that at least a portion of beam 110 acts on wire 140 during the welding process. To do. In such an embodiment, laser beam 110 is used to assist in melting wire 140 to weld wire 140 to weld pool P. Assisting the melting of the wire 140 using the beam 110 prevents the wire 140 from rapidly cooling the weld pool P when the temperature is too low for the wire 140 to be quickly consumed in the weld pool P. To help. However, as previously mentioned, in some embodiments (as shown in FIG. 15), the melting of the filler wire 140 is accomplished by the heat of the weld pool, so that the energy source 120 and the beam 110 are filled with the filler wire 140. None of the parts melts clearly.

  In the embodiment shown in FIG. 15, the wire 140 follows the beam 110 and is aligned with the beam 110. However, the present invention is not limited to this configuration because the wire 140 can precede the beam 110 (in the direction of travel). Further, the wire 140 does not need to be aligned with the beam in the moving direction, and the wire may be applied to the weld pool from any direction as long as suitable melting of the wire occurs in the weld pool.

  16A-16F show various melt pools P with the laser beam 110 showing its footprint. As shown, in some exemplary embodiments, the molten pool P has a circular footprint. However, the embodiment of the present invention is not limited to this configuration. For example, the weld pool may have an oval or other shape.

  16A to 16F show the beam 110 having a circular cross section. Again, other embodiments of the present invention are not limited in this regard. This is because the beam 110 can have an ellipse, rectangle or other shape to effectively form the weld pool P.

  In some embodiments, the laser beam 110 can be stationary relative to the weld pool P. That is, the beam 110 remains in a relatively constant position with respect to the weld pool P during welding. However, as illustrated in FIGS. 16A-16D, other embodiments are not limited to such a form. For example, FIG. 16A shows an embodiment in which the beam 110 is moved around the weld pool P in a circle. In this figure, the beam 110 moves so that at least one point in the beam 110 always overlaps the center C of the weld pool. In other embodiments, a circular pattern is used, but the beam 110 does not contact the center C. FIG. 16B shows an embodiment in which the beam is moved back and forth along one line. This embodiment can be used to lengthen or widen the weld pool P depending on the desired shape of the weld pool P. FIG. 16C shows an embodiment using two different beam cross sections. The first beam cross section 110 has a first shape, and the second beam cross section 110 'has a second cross section. Such an embodiment can be used to maintain a larger weld pool size (as needed) while increasing penetration at some point in the weld pool P. This embodiment can be realized by using a single laser 120, changing its beam shape by using laser lenses or optics, or by using multiple lasers 120. FIG. 16D shows the beam 110 moved elliptically in the weld pool P. FIG. Again, such a pattern can be used to lengthen or widen the weld pool P as required. The beam 110 can be moved in another way to form the weld pool P.

  16E and 16F show cross sections of workpiece W and weld pool P using different beam intensities. FIG. 16E shows a shallow and wide weld pool P formed by a wider beam 110, while FIG. 16F shows a deep and narrow weld pool P, commonly referred to as a “keyhole”. In this embodiment, the beam is focused so that its focal point is near the top surface of the workpiece W. Such focusing allows the beam 110 to penetrate the entire depth of the workpiece and can assist in forming a back bead BB on the bottom surface of the workpiece W. The intensity and shape of the beam will be determined based on the desired characteristics of the weld pool during welding.

  Laser 120 can be moved, translated, or manipulated by any known method and apparatus. Since laser movement and optics are generally known, a detailed description thereof is omitted herein. FIG. 17 shows a system 1700 according to an exemplary embodiment of the present invention. In system 1700, laser 120 can be moved and its optics (such as its lens) can be changed or adjusted during operation. In this system 1700, a detection / control unit 195 is coupled to both the motor 1710 and the optical drive unit 1720. Motor 1710 moves or translates laser 120 so that the relative position of beam 110 relative to the weld pool can be moved during welding. For example, the motor 1710 translates the beam 110 back and forth, for example, or moves it in a circular shape. Similarly, the optical drive unit 1720 receives instructions from the detection / control unit 195 to control the optics of the laser 120. For example, the optical drive unit 1720 can move or change the focal point of the beam 110 relative to the surface of the workpiece, thereby changing the weld pool penetration or depth. Similarly, the optical drive unit 1720 changes the shape of the beam 110 by changing the optics of the laser 120. Thus, during welding, the detection / control unit 195 controls the laser 120 and beam 110 to maintain and / or change the characteristics of the weld pool during operation.

  As previously described with reference to FIG. 7B, hot wire laser welding consistent with the present invention allows for narrow gap welding that may be difficult with arc-type welding processes or laser only welding processes. To do. In addition to the advantages previously described, the hot wire laser welding of the present invention enables the welding of thin workpieces, for example, less than 10 mm, which was not possible with conventional arc welding processes. This is especially true when the weld depth is greater than the material thickness. For example, as shown in FIG. 20A, the joint depth is greater than the thickness of each workpiece 115A / 115B. That is, in exemplary embodiments of the present invention, the joint depth or weld bead depth is greater than the thickness of at least one of the workpieces, and in other embodiments, the bead is greater than the thickness of both workpieces. The depth is great. However, arc welding processes such as GMAW tend to provide a wider weld pool and higher heat input that can deform the workpiece. This is because such a method requires an excess of filler. This is because, as explained above, the arc welding process requires a wider gap to provide shielding gas and prevent the iron side walls of the weld groove from interfering with the arc. The heat input required to melt excess filler can deform thin workpieces.

  In the arc welding process, attempts to narrow the joint gap width can lead to another problem. For example, as shown in FIG. 20A, a weld pool in an arc-type process can bridge a joint without deep penetration, which becomes a stress riser in the finished joint. In addition, as shown in FIG. 20A, when joining thin workpieces 115A and 115B, the arc-type process creates a wide weld cap, making it difficult to determine the depth of the weld. In general, the visible heat line 116 on the workpiece 115B is an indicator of the depth of penetration of the weld pool, ie, the indicator of the bottom of the weld joint. However, a wide welding cap in a typical arc welding process such as the GMAW process covers the outer end of a thin workpiece such as the workpiece 115B. The upper outer edge of the workpiece corresponds to the upper part of the weld joint. If it is not known where the upper outer end of the workpiece 115B (ie, the upper part of the welded joint) is, it is difficult to know the depth of penetration.

  While laser-only welding processes can control the above mentioned drawbacks with respect to heat input and weld cap size, laser-only welding processes have other drawbacks. For example, in a laser-only welding process, the laser is more focused than a build-up process to provide the strength to melt the workpiece and form a weld pool. In general, however, the workpiece must fit very tightly, such as a gap of less than 1 mm. Otherwise, the laser passes through the gap in the joint and / or the weld pool formed by the laser cannot bridge the gap.

  As shown in FIG. 20B, a hot wire laser welding process consistent with the present invention can eliminate the disadvantages previously described. In addition, since the process is a hot wire laser process, there is little or no spatter associated with the process and no shielding gas is required. The setup and control of the laser and hot wire are similar to those of the laser 120 and hot wire 140 shown in FIG. 7B. Accordingly, further description of the setup and control of the hot wire laser system is omitted. In FIG. 20B, the workpieces 115A and 115B are arranged with a narrow gap GP. The gap GP depends on the bridging ability of the weld bead formed by melting of the workpieces 115A and 115B and the hot filler wire 140. However, it is conceivable that the gap GP has an average gap width of 1 to 3 times the diameter of the wire 140. In other exemplary embodiments, the average gap width is 1-2 times the diameter of the wire 140. In general, the average gap width means the average distance between each side wall of the joint due to the depth of the joint. In the exemplary embodiment of the present invention, laser 120 and hot wire 140 form a weld pool that is approximately twice the diameter of hot wire 140. Also, due to the characteristics of the embodiments of the present invention (described above), the process of the present invention allows the penetration depth to be 4-10 times the diameter of the hot wire 140, while In embodiments, the penetration can be 6 to 10 times the diameter of the hot wire 140. Although the above description refers to the “penetration” depth, it is understood that this includes the depth of the top. For example, as shown in FIG. 20A, because there is a gap between the workpieces, the laser does not have to penetrate the depth of the workpiece completely, but builds a weld bead in the joint gap as shown. Used for. In some embodiments, the joint is raised as opposed to passing completely through the workpiece, so that more laser energy is required than using a laser to form a keyhole in the workpiece. Few. Moreover, the thickness of a workpiece may be comparatively thin from the advantage of embodiment of this invention. For example, as shown in FIG. 20B, the workpieces 115A and 115B may have a thickness of 4-15 mm at the weld joint, and in some embodiments may have a thickness of 4-10 mm, but this is not evident. No deformation is brought about. Such thickness is the average thickness of the workpiece for the depth of the weld joint in the weld joint, and may or may not be the length for the entire length of the weld joint. Thus, exemplary embodiments of the present invention can provide a welded joint that has a very narrow gap but a deep penetration that is not obtainable with conventional welding operations.

  As shown in FIG. 20B, the previously described hot wire laser process creates a penetration down to the root of the joint and forms a strong joint using less filler and heat input than a typical arc welding process. In addition, the deposition rate and wire feed rate are comparable to those of conventional arc welding processes. For example, a moving speed faster than 100 ipm and a wire feeding speed faster than 400 ipm can be realized based on the welding parameters. Moreover, since the welding cap does not cover the upper end of the thin workpiece 115B as in the arc type process, the inspection of the welded portion is easy. Since the top outer end of the workpiece 115B can be seen, the distance between the top of the joint (top) and the bottom of the joint (heat line 116) can be easily measured.

  In each of FIGS. 1, 14 and 17, the laser power supply 130, hot wire power supply 170 and detection / control unit 195 are shown separately for clarity. However, in an embodiment of the present invention, these components can be integrated into a single welding system. In aspects of the present invention, the components individually described above need not be maintained in separate physical units or stand-alone structures.

  Although the present invention has been described with reference to particular embodiments, those skilled in the art will recognize that various modifications can be made and substituted for equivalents without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope of the invention. Accordingly, the invention is not limited to the specific embodiments disclosed, but the invention includes all embodiments that fall within the scope of the appended claims.

100 System 110 Laser Beam 110A Laser Beam 115 Workpiece 115A Workpiece 115B Workpiece 116 Heat Line 120 Laser Device 120A Laser Device 121 Beam Splitter 125 Direction 130 Power Supply 140 Filler Wire 150 Filler Wire Feeder 160 Contact Chip 170 Power Supply 180 Motion Controller 190 Robot 195 Current control subsystem 200 Start method 220 Step 230 Step 240 Step 250 Step 260 Step 310 Step 320 Step 330 Step 340 Step 350 Step 410 Voltage waveform 411 Point 412 Point 420 Current waveform 425 Lamp 430 Interval 440 Set value 450 Output current Level 510 Current waveform 511 points 512 Points 520 Current waveform 525 Heating current level 530 Period 601 Lap joint surface 601A Melt pool 603 Lap joint surface 603A Melt pool 605 Surface 701 Inclined surface 703 Inclined surface 705 Gap 707 Weld bead 801 Weld pool 803 Weld pool 901 Weld pool 903 Weld pool 1000 Welded joint 1010 Laser source 1011 Beam 1012 Weld pool 1020 Laser source 1021 Laser beam 1022 Weld pool 1030 Filler wire 1030A Filler wire 1110 Coil 1200 System 1210 Power supply 1220 User input unit 1222 Negative electrode 1223 Detection lead 1230 CPU / controller 1240 Voltage detection circuit 1250 Power module 1400 System 1410 Sensor 1420 Sensor 1700 Temu 1710 Motor 1720 optical drive unit 1800 circuit 1801 resistors 1803 switch 1901 laser shroud assembly 1903 fume exhaust system A point B point BB back bead C point / center point D E point L length P weld puddle WB weld bead X distance Z distance

Claims (6)

A welding system,
At least one high-strength energy source for directing high-strength energy to a plurality of workpieces to form a weld pool in an open root weld joint;
A heating power source for providing a wire heating signal to at least one filler wire and heating the filler wire to a temperature at which the filler wire melts in the weld pool when the filler wire contacts the weld pool;
A wire feed mechanism that advances the filler wire into the weld pool such that the filler wire maintains contact with the weld pool during a welding operation;
Including
The heating power source observes feedback from the heating signal of the filler wire and heats the filler wire so that no arc is generated between the filler wire and the weld pool when the feedback reaches an upper threshold. Turn off the signal, and the heating power source turns on the filler wire heating signal to continue heating the filler wire;
The open root weld joint is formed by at least two workpieces having an average gap between 1 and 3 times the diameter of the filler wire, and the depth of the open root weld joint is 4 to 4 times the diameter of the filler wire. 10 times the system.   The system of claim 1, wherein the depth of the open root weld joint is 6 to 10 times the diameter of the filler wire and / or the average gap is 1 to 2 times the diameter of the filler wire.   The system according to claim 1 or 2, wherein a thickness of at least one of the workpieces in the open root weld joint is 4 to 15 mm.   The system according to any one of claims 1 to 3, wherein the moving speed of the welding is at least 100 ipm.   The system of claim 1, wherein the filler wire heating signal heats the filler wire to 90% or more of its melting temperature.   6. The system according to any one of claims 1-5, wherein the threshold is a voltage threshold and / or the voltage threshold is 16 volts or less.

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