Abstract:
A system for and a method of controlling filler wire is provided. The system includes a high intensity energy source configured to heat at least one workpiece to create a molten puddle on a surface of the at least one workpiece. A filler wire feeder is configured to feed a filler wire into said molten puddle, and a travel direction controller is configured to advance the high intensity energy source and the filler wire in a travel direction to deposit the filler wire on the at least one workpiece. The system also includes a filler wire controller configured to move the filler wire in at least a first direction during the feeding and advancing of the filler wire. At least the first direction is controlled to obtain a desired shape, profile, height, size, or an admixture of a bead formed by the molten puddle.

Description:
PRIORITY 
     The present application claims priority to U.S. Provisional Patent Application No. 61/668,818, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     Certain embodiments relate to using filler wire in overlaying, welding and joining applications. More particularly, certain embodiments relate to controlling filler wire in a system and method for any of brazing, cladding, building up, filling, hard-facing overlaying, joining and welding applications. 
     BACKGROUND 
     The traditional filler wire method of welding (e.g., a gas-tungsten arc welding (GTAW) filler wire method) provides increased deposition rates and welding speeds over that of traditional arc welding alone. The filler wire, which leads a torch, is resistance-heated by a separate power supply. The wire is fed through a contact tube toward a workpiece and extends beyond the tube. The extension is resistance-heated such that the extension approaches or reaches the melting point and contacts the weld puddle. A tungsten electrode may be used to heat and melt the workpiece to form the weld puddle. The power supply provides a large portion of the energy needed to resistance-melt the filler wire. In some cases, the wire feed may slip or falter and the current in the wire may cause an arc to occur between the tip of the wire and the workpiece. The extra heat of such an arc may cause burn through and spatter. In addition, because the traditional filler wire method uses an arc to transfer the filler material to the weld, it may be difficult to get the desired weld profile and/or control the cooling rate of the weld puddle. 
     Further limitations and disadvantages of conventional, traditional, and proposed approaches will become apparent to one of skill in the art, through comparison of such approaches with embodiments of the present invention as set forth in the remainder of the present application with reference to the drawings. 
     SUMMARY 
     Embodiments of the present invention comprise controlling filler wire in a system and method for any of brazing, cladding, building up, filling, hard-facing overlaying, welding, and joining applications. In some embodiments, the method includes heating at least one workpiece with a high energy heat source to create a molten puddle on a surface of the at least one workpiece and feeding a filler wire into the molten puddle. The method also includes advancing each of the high energy heat source and the filler wire in a travel direction to deposit the filler wire on the at least one workpiece. The filler wire is moved in at least a first direction during the feeding and advancing of the filler wire, where the at least first direction is different from the travel direction. The method further includes controlling at least the movement of the filler wire in the at least first direction to obtain a desired shape, profile, height, size, or an admixture of a bead formed by the molten puddle. 
     In some embodiments, the system includes a high intensity energy source configured to heat at least one workpiece to create a molten puddle on a surface of the at least one workpiece. A filler wire feeder is configured to feed a filler wire into the molten puddle. A travel direction controller is configured to advance each of the high intensity energy source and the filler wire in a travel direction to deposit the filler wire on the at least one workpiece. The system also includes a filler wire controller configured to move the filler wire in at least a first direction during the feeding and advancing of the filler wire, where the at least first direction is different from said travel direction. At least the movement of the filler wire in the at least first direction is controlled to obtain a desired shape, profile, height, size, or an admixture of a bead formed by the molten puddle. 
     The method also includes applying energy from a high intensity energy source to the workpiece to heat the workpiece at least while applying the flow of heating current. The high intensity energy source may include at least one of a laser device, a plasma arc welding (PAW) device, a gas tungsten arc welding (GTAW) device, a gas metal arc welding (GMAW) device, a flux cored arc welding (FLAW) device, and a submerged arc welding (SAW) device. 
     These and other features of the claimed invention, as well as details of illustrated embodiments thereof, will be more fully understood from the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or other aspects of the invention will be more apparent by describing in detail exemplary embodiments of the invention with reference to the accompanying drawings, in which: 
         FIG. 1  illustrates a functional schematic block diagram of an exemplary embodiment of a combination filler wire feeder and energy source system for any of brazing, cladding, building up, filling, hard-facing overlaying, joining, and welding applications; 
         FIGS. 2A-2C  illustrate a method of controlling a filler wire that can be used by the system of  FIG. 1 ; 
         FIGS. 3A and 3B  illustrate a method of controlling a filler wire that can be used by the system of  FIG. 1 ; and 
         FIGS. 4A and 4B  illustrate a method of controlling filler wires that can be used by the system of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments of the invention will now be described below by reference to the attached Figures. The described exemplary embodiments are intended to assist the understanding of the invention, and are not intended to limit the scope of the invention in any way. Like reference numerals refer to like elements throughout. 
     It is known that welding/joining operations typically join multiple workpieces together in a welding operation where a filler metal is combined with at least some of the workpiece metal to form a joint. Because of the desire to increase production throughput in welding operations, there is a constant need for faster welding operations, which do not result in welds which have a substandard quality. This is also true for cladding/surfacing operations, which use similar technology. It is noted that although much of the following discussions will reference “welding” operations and systems, embodiments of the present invention are not just limited to joining operations, but can similarly be used for cladding, brazing, overlaying, etc.—type operations. Furthermore, there is a need to provide systems that can weld quickly under adverse environmental conditions, such as in remote work sites. As described below, exemplary embodiments of the present invention provide significant advantages over existing welding technologies. Such advantages include, but are not limited to, using multiple filler wires, adjusting weld profiles, controlling the cooling rate of the weld puddle, reduced total heat input resulting in low distortion of the workpiece, very high welding travel speeds, very low spatter rates, welding with the absence of shielding, welding plated or coated materials at high speeds with little or no spatter, and welding complex materials at high speeds. 
       FIG. 1  illustrates a functional schematic block diagram of an exemplary embodiment of a combination filler wire feeder and energy source system  100  for performing any of brazing, cladding, building up, filling, hard-facing overlaying, and joining/welding applications. The system  100  includes a laser subsystem  130 / 120  capable of focusing a laser beam  110  onto a workpiece  115  to heat the workpiece  115  and form a weld puddle  145 . The laser subsystem is a high intensity energy source. The laser subsystem can be any type of high energy laser source, including but not limited to carbon dioxide, Nd:YAG, Yb-disk, YB-fiber, fiber delivered or direct diode laser systems. Further, even white light or quartz laser type systems can be used if they have sufficient energy. Other embodiments of the system may include at least one of an electron beam, 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 arc welding subsystem serving as the high intensity energy source. The following specification will repeatedly refer to the laser system, beam and power supply, however, it should be understood that this reference is exemplary as any high intensity energy source may be used. For example, a high intensity energy source can provide at least 500 W/cm 2 . 
     It should be noted that the high intensity energy sources, such as the laser devices  120  discussed herein, should be of a type having sufficient power to provide the necessary energy density for the desired welding operation. That is, the laser device  120  should have a power sufficient to create and maintain a stable weld puddle throughout the welding process, and also reach the desired weld penetration. For example, for some applications lasers should have the ability to “keyhole” the workpieces being welded. This means that the laser should have sufficient power to fully penetrate the workpiece, while maintaining that level of penetration as the laser travels along the workpiece. Exemplary lasers should have power capabilities in the range of 1 to 20 kW, and may have a power capability in the range of 5 to 20 kW. Higher power lasers can be utilized, but can become very costly. 
     The laser subsystem  130 / 120  includes a laser device  120  and a laser power supply  130  operatively connected to each other. The laser power supply  130  provides power to operate the laser device  120 . Laser device  120  allows for precise control of the size and depth of the weld puddle  145  as the laser beam  110  can be focused/de-focused easily or have its beam intensity changed very easily. Because of these abilities the heat distribution on the workpiece  115  can be precisely controlled. This control allows for the creation of a very narrow weld puddle for precise welding as well as minimizing the size of the weld zone on the workpiece  115 . 
     The system  100  also includes a filler wire feeder subsystem capable of providing at least one resistive filler wire  140  to make contact with the workpiece  115  in the vicinity of the laser beam  110 . Of course, it is understood that by reference to the workpiece  115  herein, the molten puddle, i.e., the weld puddle  145 , is considered part of the workpiece  115 , thus reference to contact with the workpiece  115  includes contact with the puddle  145 . The filler wire feeder subsystem includes a filler wire feeder  150 , a contact tube  160 , and a wire power supply  170 . During operation, the filler wire  140  is resistance-heated by electrical current from the power supply  170  which is operatively connected between the contact tube  160  and the workpiece  115 . In accordance with an embodiment of the present invention, the power supply  170  is a pulsed direct current (DC) power supply, although alternating current (AC) or other types of power supplies are possible as well. In some exemplary embodiments, the filler wire  140  is preheated by power supply  170  to at or near its melting point. Accordingly, its presence in the weld puddle  145  will not appreciably cool or solidify the puddle  145  and the filler wire  145  is quickly consumed into the weld puddle  145 . 
     The power supply  170 , filler wire feeder  150 , and laser power supply  130  may be operatively connected to sensing and control unit  195 . The control unit  195  can control the welding operations such as wire feed speed, wire temperatures, and weld puddle temperature—to name just a few. To accomplish this, the control unit  195  can receive inputs such as the power used by power supplies  130  and  170 , the voltage at contact tube  160 , the heating current(s) through the filler wire(s), the desired and actual temperature(s) for the filler wire(s), etc. U.S. patent application Ser. No. 13/212,025, titled “Method And System To Start And Use Combination Filler Wire Feed And High Intensity Energy Source For Welding,” filed Aug. 17, 2011, is incorporated by reference in its entirety, describes exemplary sensing and control units, including exemplary monitoring and control methodologies, that may be incorporated in the present invention. 
     In exemplary embodiments of the present invention, the weld profile the shape and/or size of the weld puddle  145 , can be changed by controlling the movement of the wire  140  relative to the weld puddle  145 . As illustrated in  FIG. 1 , the impact location of the filler wire  140  in the weld puddle  145  may be controlled by filler wire motor  1730 , which controls contact tube  160 . The motor  1730  moves or translates the contact tube  160  such that the position of the wire  140  relative to the weld puddle  145  is moved during welding. In an exemplary embodiment, the filler wire  140  impacts the weld puddle  145  at the same location as the laser beam  110 . In such cases, the laser beam  110  may aid in melting the filler wire  140 . However, in other exemplary embodiments, the filler wire  140  can impact the same weld puddle  145  remotely from the laser beam  110 . Of course, when an arc-type heating subsystem used instead of a laser subsystem, the filler wire  140  impacts the weld puddle  145  remotely from the arc. In some exemplary embodiments, the filler wire motor  1730  will control contact tube  160  such that the movement of wire  140  within the weld puddle  145  is coordinated with the movement of laser beam  110 . In this regard, the motor  1730  may be operatively connected to and communicate with the sensing and control unit  195  and/or directly with laser motion control subsystem  1710 / 1720 . The laser motion control subsystem  1710 / 1720  includes motor  1710  and optics drive unit  1720 . The motor  1710  moves or translates the laser  120  such that the position of the beam  110  relative to the weld puddle  145  is moved during welding. That is, while the laser beam  110  and wire  140  are moved relative to the workpiece.  115  during the welding process (i.e., the direction of the weld (see arrow  111 )), the laser beam  110  can also be moved relative to the weld puddle  145 . For example, based on the welding parameters, the motor  1710  can translate the beam  110  back and forth in-line with the direction of the weld, back and forth along the width of the weld, in a circular pattern, in an elliptical pattern, etc. Alternatively, or in addition to moving the laser beam  110 , the optics drive unit  1720  can control the optics of the laser  120 , which control the shape and/or intensity of laser beam  110 . For example, the optics drive unit  1720  can cause the focal point of the beam  110  to move or change relative to the surface of the workpiece  115 , thus changing the penetration or depth of the weld puddle  145 . In some exemplary embodiments, the optics drive unit  1720  can cause the optics of the laser  120  to change the shape of the beam  110  and, thus the shape of weld puddle  145 . The operation of the laser motion control subsystem  1710 / 1720  is further discussed U.S. patent application Ser. No. 13/212,025, titled “Method And System To Start And Use Combination Filler Wire Feed And High Intensity Energy Source For Welding,” filed Aug. 17, 2011, and incorporated by reference in its entirety. 
     By being able to move the wire  140  relative to the puddle, embodiments of the present invention are capable of adjusting the shape, profile and height of the puddle, as well as obtaining the desired weld puddle admixture during welding. For example, if the weld puddle  145  is relatively large due, the movement of the wire  140  will allow the wire  140  to be deposited and distributed relatively evenly throughout the puddle  145  during welding/cladding. Moreover, it may be desirable to deliver the 140 to certain portions of the puddle  145  at different times during the operation. Embodiments of the present invention allow this to occur by delivering the wire  140  to the proper location in the puddle  145  at the appropriate time. Further, mixing of the weld puddle can be enhanced by moving the wire  140  relative to the puddle during the operation. 
     In some exemplary embodiments, the sensing and control unit  195  may synchronize the movement of the wire  140  using the rotor  1730  with that of laser beam  110 . In an exemplary embodiment; as illustrated in  FIGS. 2A and 2B , the laser beam  110  and wire  140  are both moved in a circular pattern by motors  1710  and  1730 , respectively. The relative position of wire  140  with respect to beam  110  can be adjusted by motor  1730  to ensure that, as the beam  110  and wire  140  move forward in the direction of the weld (see arrow  111 ) the wire  140  impinges the weld puddle  145  at a point where the puddle  145  is at its optimum temperature. For example, as shown in  FIG. 2B , the wire  140  will impinge point X on weld puddle  145  immediately after the beam  110  heats it. Thus, embodiments of the present invention san have the wire  140  follow the movement of the beam  110  (or other heat source) to optimize absorption of the wire  140  into the puddle  145 , which is generally shown in  FIG. 2C . Of course, the exact timing on the optimum impingement point may vary depending on the temperature of the weld puddle  145 , the intensity of laser beam  110 , the type of filler wire  140 , the feed speed of the filler wire  140 , etc. 
     In addition, the wire  140  and the laser beam  110  may follow other patterns and their movements need not be synchronized. For example,  FIGS. 3A and 3B  illustrates an embodiment in which the laser beam  110  and the filler wire  140  are translated back-and-forth along a single line. Depending on whether the beam  110  and wire  140  are translated across the width of the weld puddle  145  ( FIG. 3A ) or in-line with the weld puddle ( FIG. 3B ), these embodiments can be used to either elongate or widen the puddle  145  as needed depending on the desired shape of the weld. Of course numerous other patterns are possible. For example, the beam  110  and the wire  140  can be translated in an elliptical pattern in the weld puddle  145  rather than the circular pattern shown in  FIGS. 2A and 2B . Of course, any combination of such patterns can be used to either elongate or widen the weld puddle  145  as needed to get the desired weld profile. In addition, U.S. patent application Ser. No. 13/212,025, titled “Method And System To Start And Use Combination Filler Wire Feed And High Intensity Energy Source For Welding,” filed Aug. 17, 2011, and incorporated by reference in its entirety, provides additional patterns that may be used in the present invention. 
     In some embodiments, the motion of the wire  140  is independent of the motion of the laser beam  110 . That is, the patterns of the laser beam  110  and the wire  140  need not be the same. For example, the laser beam  110  may have an elliptical pattern while the wire  140  has a circular or back-and-forth pattern. In still other embodiments, the laser beam  110  can remain stationary with respect to the weld puddle  145 , and only the wire  140  is moved or translated relative to the weld puddle  145 . 
     In some exemplary embodiments of the present invention, the filler wire  140  may be used to control the rate of cooling for the weld puddle  145 . For example, the filler wire  140  may be cooler than the weld puddle  145  in order to cool and solidify the weld. Such a welding system may be advantageous in out-of-position welding because the weld puddle  145  will start to cool and solidify before it can sag or spill out of the weld joint. However, to prevent undesirable localized (or uneven) cooling or solidification within the weld puddle  145 , motor  1730  can move the wire  140  as discussed above to ensure that the cooler filler wire  140  is spread evenly throughout the weld puddle  145 . Conversely, in some welding operations, it may be desirable to have the filler wire  140  hotter than the weld puddle  145  in order to prevent the weld puddle  145  from cooling or solidifying too quickly. Again, the filler wire  140  may be moved by motor  1730  to keep the temperature of weld puddle  145  uniform. 
     In the embodiment shown in  FIGS. 2A-3B , the filler wire  140  trans the beam  110  during the welding operation. However, that is not necessary as the filler wire  140  can be positioned in the leading position. Further, it is not necessary to have the wire  140  in line with the beam  110  in the travel direction, but the wire can impinge the puddle from any direction so long as the filler wire  140  impacts the same weld puddle  145  as the beam  110 . 
     In the embodiments discussed above, only one filler wire was used. However, the present invention is not limited to directing a single filler wire to the weld puddle  145 . Unlike most welding processes the filler wire  140  makes contact and is plunged into the weld puddle  145  during the welding process. This is because this process does not use a welding arc to transfer the filler wire  140  but rather simply melts the filler wire  140  into the weld puddle  145 . Because no welding arc is generated in the welding process described herein, more than one filler wire can be directed to any one weld puddle, i.e. the feeder subsystem may be capable of simultaneously providing one or more filler wires. By increasing the number of filler wires to a given weld puddle the overall deposition rate of the weld process can be significantly increased without a significant increase in heat input. Thus, it is contemplated that open root weld joints can be filled in a single weld pass. In addition, along with the deposition rate of the filler wire, the shape and characteristics of the weld can be changed as desired by using additional filler wires. To the extent multiple filler wires are utilized, and both are heated as described herein, embodiments of the present invention can utilize a single power supply  170  for each wire. 
     In some exemplary embodiments, as illustrate in  FIGS. 4A and 4B , two filler wires impinge weld puddle  145 . Embodiments where two or more filler wires are used are similar to the embodiments discussed above. Accordingly, for brevity, only the relevant differences will be discussed. As shown in  FIGS. 4A and 4B , the second filler  140 ′ impinges the weld puddle  145  in-line with the wire  140  in the width direction. However, this configuration is not limiting and wire  140 ′ may impinge the puddle  145  in-line with wire  140  in the direction of the weld (see arrow  111 ). Of course, the wires  140  and  140 ′ need not be in the trailing position as shown in  FIGS. 4A and 4B , and either wire  140 ′ or  140  or both may be in the leading position during welding operations. Wire  140 ′ may be composed of the same material as wire  140  or it may be composed of a different material depending on the desired weld. For example, wire  140 ′ may be used for hard-facing and/or providing corrosion resistance to the workpiece, and wire  140  may be used to add structure to the workpiece. 
     In some exemplary embodiments, wire  140 ′ may be controlled by a motor in a manner similar to wire  140  as discussed above. For example, as shown in  FIGS. 4A and 4B , wire  140 ′ is being moved in a clockwise pattern by a motor (not shown) and wire  140  in a counter-clockwise pattern. The movements of wires  140  and  140 ′ can be controlled as discussed above to achieve the desired weld shape. Of course, the wires are not limited to circular patterns or to moving in opposite directions (i.e., clockwise and counter-clockwise). The wires  140  and  140 ′ can be controlled using any combination of the patterns discussed above to achieve the desired weld profile. 
     In some embodiments, the second filler wire may be used to control the temperature of the weld  145 . For example, the feed rate and/or the temperature of the second filler may be controlled based on the desired temperature of the weld puddle  145 . Similar to the exemplary embodiments discussed above, the second filler wire may be cooler or hotter than the weld puddle temperature and wire  140 ′ may be controlled to ensure that the temperature of weld  145  is uniform. 
     In  FIG. 1 , the laser power supply  130 , hot wire power supply  170  and sensing and control unit  195  are shown separately for clarity. However, in embodiments of the invention these components can be made integral into a single welding system. Aspects of the present invention do not require the individually discussed components above to be maintained as separately physical units or stand alone structures. 
     While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention lot be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.