JP2015522426A - Method and system for starting and stopping hot wire processing - Google Patents

Abstract

A method and system (100) for starting and / or stopping hot wire (140) processing. A hot wire system includes a filler wire feeder (150) including a contact tube (160) for holding a filler wire (140), a wire feed mechanism, a power source (130, 170) for applying a heating current to the wire; and , Including a controller (180) coupled to the supply mechanism and the power source (130, 170). The controller (180) adjusts the heating current to the wire (140) to form the molten pool (116, 117) using an arc to initiate the hot wire process (280, 380) and Configured to position relative to the workpiece (115). The controller also adjusts the supply of wire to the melt pool, adjusts the current to the wire and / or adjusts the wire to retract out of the melt pool in a stable manner when hot wire processing is stopped. It may be configured to perform one of the pulsations.

Description

  This application is a partial continuation application that claims the benefit of priority to US patent application Ser. No. 13 / 212,025, filed Aug. 17, 2011. This US patent application is a continuation-in-part of US patent application Ser. No. 12 / 352,667, filed Jan. 13, 2009. Each of these US patent applications is incorporated by reference in its entirety.

  The invention relates to a hot wire process start method according to claim 1, a hot wire system according to claims 11 to 14 and a hot wire stop method according to claim 15. The subject invention relates generally to systems and methods for starting and / or stopping hot wire processing. The hot wire process is used, for example, in overlaying, welding, and / or other joining applications. More specifically, some embodiments use a controlled filler wire feeder and energy source in combination with a high-strength energy source for any one of coating, joining, and welding applications. Thus, it relates to a system and method for starting and / or stopping hot wire processing.

  In hot wire processing or filler wire processing, a high intensity energy source, such as a laser, a non-consumable tungsten electrode or other high energy arc or plasma treatment, heats and melts the workpiece (workpiece) and puddles. ) (Or melted paddle). The filler wire is advanced toward the workpiece and the molten pool. The wire is resistively heated by a separate energy source so that the wire approaches or reaches its melting point and contacts the molten pool. The heated wire is fed into the molten pool for hot wire processing. As a result, the filler wire moves to the workpiece by simply melting the filler wire into the melt pool. Alternatively, the filler wire may be solid when the wire enters the molten pool. For example, 30% of the filler wire can be solid when the wire enters the molten pool. Since the filler wire is preheated at or near its melting point, its presence in the melt pool does not cool or solidify appreciably, but quickly enters the melt pool. Absorbed. One problem associated with starting or stopping hot wire processing is the occurrence of wire spatter in each case where the wire is introduced into or retracted from the melt pool. Prior to its complete formation, the melt pool is unstable, resulting in wire sputtering resulting from the introduction of the wire into the melt pool. Pool instability at the time of wire introduction can be seen in the voltage, current or power traces of the hot wire process shown in FIG. Shown in FIG. 7 is the oscillation in the voltage / current / power trace at the beginning of a known hot wire process. The oscillations in the voltage trace are due, at least in part, to repeated arcing events between the wire and the workpiece due to incomplete formation of the melt pool. At the end of the hot wire process, the wire is maintained in the molten pool to prevent wire spattering. However, in order to separate the wire from the pool, the hot wire process must be stopped and the wire must be cut. Thus, there is a need for starting and / or stopping hot wire processing that minimizes wire spatter when introducing or retracting wires from the molten pool.

  Further limitations and disadvantages of conventional, traditional and proposed approaches are described in the remainder of this application with reference to the drawings, such approaches and embodiments of the invention. And will be apparent to those skilled in the art.

  One object of the present invention is to overcome these limitations and disadvantages.

  This problem is solved by the method for starting hot wire processing according to claim 1, by the hot wire system according to claims 11 to 14 and by the method for stopping hot wire processing according to claim 15. Preferred embodiments of the invention are the subject matter of the subclaims. Embodiments of the present invention include systems and methods for starting and stopping a filler wire feeder and energy source system combination. The first embodiment of the present invention provides a method of hot wire processing between a filler wire and a workpiece. The subject method has an initiation process. The initiation process includes establishing an arc between the filler wire and the workpiece to form a molten pool in the workpiece; maintaining the molten pool by a high intensity energy source away from the wire; arc voltage Advancing the wire into the melt pool upon establishing and applying a heating current to the wire to terminate the arc and bring the wire to approximately its melting point for hot wire processing; including. According to a further embodiment of the method, the sensing signal is an open circuit voltage of 3 volts. According to a further embodiment of the method, the high intensity energy source is an arc generating source. The problem according to the invention is also solved by a hot wire system having a feeder for advancing and retracting the distal end of the filler wire relative to the workpiece. The system further includes a power source for application to wires, sensing signals, arcing current and heating current. The system further includes a controller coupled to the feeder and the power source to initiate hot wire processing. The control unit positions the wire with respect to the workpiece and controls each of the sensing signals. The arcing signal and the heating current include adjusting the sensing signal to advance the distal end of the wire toward the workpiece and determine when the distal end is in contact with the workpiece. . The system further includes retracting the distal end of the wire from the workpiece and adjusting the arcing current so as to form an arc between the distal end and the workpiece to form a molten pool. . The system further includes advancing the wire into the melt pool and adjusting the heating current to melt the wire into the melt pool. The system further includes a high intensity energy source for providing heat to the molten pool. According to one preferred embodiment of the system, the power source comprises a first power source for applying the sensing signal, a second power source for applying the arc generating current and a third power source for applying the heating current. It includes a plurality of power supply sources including a power supply source.

  One other embodiment provides a method for stopping a hot wire process that causes a heating current to melt a filler wire into a molten pool of workpieces. The stopping method includes reducing the feed rate of the wire into the molten pool and maintaining the molten pool with a high intensity energy source. In one aspect, the stopping method further includes stopping the heating current to the wire and applying a plurality of current pulses to the wire such that the distal end of the wire is removed from the molten pool. One other aspect or alternative method of stopping is to retract the wire from the melt pool, to sense the formation of an arc between the wire and the workpiece, and to the wire before the arc is formed. Ending the heating current. In yet another aspect or alternative of the stopping method, the wire is removed from the melt pool such that at least some of the heating current applied to the wire leaves the wire extension in the melt pool. Retracted from the pool to separate and separate. Energy from a high intensity energy source is applied to the wire extension so as to melt the extension into the molten pool.

  These and other features of the claimed invention, as well as the details of these described embodiments will be more fully understood from the following description and drawings.

These and / or other aspects of the invention will become apparent from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings.
FIG. 1 shows a schematic functional block diagram of one exemplary embodiment of a hot wire system. FIG. 1A is a detailed perspective view of a hot wire process using the system of FIG. FIG. 2 shows a flowchart of a first embodiment of a method for starting hot wire processing using the system of FIG. FIG. 3 shows a flow diagram of a second embodiment of a hot wire process startup method using the system of FIG. FIG. 4 shows a flow diagram of a first embodiment of a method for stopping hot wire processing using the system of FIG. FIG. 5 shows a flow diagram of a second embodiment of a method for stopping hot wire processing using the system of FIG. FIG. 6 shows a flow diagram of a third embodiment of a method for stopping hot wire processing using the system of FIG. FIG. 7 shows voltage, current and power traces in prior art hot wire processing.

  Exemplary embodiments of the present invention will now be described below with reference to the accompanying drawings. The illustrative embodiments described are intended to aid in understanding the invention and are not intended to limit the scope of the invention in any way. Like reference numbers refer to like elements throughout the specification.

  FIG. 1 shows a schematic functional block diagram of one exemplary embodiment of a system 100 for performing hot wire processing. The term “hot wire processing” is used herein in a broad sense and may refer to any application including coating, welding or joining. More specifically, hot wire processing includes heating a filler wire (eg, using resistance heating) to perform coating, welding and / or bonding. The coating process can include brazing, cladding, building up, filling and hard-facing. For example, in “brazing” applications, the filler metal is spread between adjacent mating surfaces by capillary action. On the other hand, in “blaze welding”, the filler metal is applied in the gap. However, as used herein, both techniques are widely referred to as coating applications. The system 100 includes a hot filler wire feeder subsystem that can supply at least one heated filler wire 140 for contacting the workpiece 115. Of course, by reference to the workpiece 115 herein, the molten pool 116 formed in the workpiece is considered to be part of the workpiece 115, and therefore a reference to contact with the workpiece 115 is As long as is present, it is understood to include contact with the reservoir.

  The hot filler wire feeder subsystem includes a filler wire feeder 150, a contact tube 160 and a hot wire power source 170. Wire 140 is fed from filler wire feeder 150 through contact tube 160 toward workpiece 115 and extends beyond tube 160. The hot wire power supply 170 may be a pulsed direct current (DC) power supply. Nevertheless, alternating current (AC) power supplies or other types of power supplies are possible as well. In response, the power source 170 may be operated to apply either one of a voltage signal or a current signal to the wire 140. The power supply 170 may include a single power supply, or more than one power supply to apply various currents or establish various voltages, as described in more detail below. May be included. Although the drawings and commentary herein refer to “wire” 140, this term is broadly intended to mean consumables, which are traditionally formed into a cylindrically shaped wire (solid or core). It should be noted that it may be in) or it may also be a strip consumable such as the type often used for cladding. However, for clarity, the consumable 140 is sometimes referred to herein as a “wire”.

  In one aspect of the subject initiation process, described in more detail below, the power source 170 is operated to apply a sensing signal to the wire 140 to determine the approach of the wire to the workpiece. In one other embodiment of the control method, the power source applies sufficient current to the wire to establish an arc between the wire and the workpiece. In one further aspect, filler wire 140 is resistively heated by the current from hot wire power supply 170. Hot wire power supply 170 is operatively connected between contact tube 160 and workpiece 115.

  The exemplary system 100 further includes a control subsystem 195. The control subsystem 195 can measure the potential difference (ie, voltage V) between the workpiece 115 and the hot wire 140 and the current (I) through the workpiece 115 and the hot wire 140. In at least one exemplary embodiment, the control subsystem 195 may be embodied as a state-based current sensing controller to adjust the function of the power source, such as output current, voltage and / or power, for example. Are operatively connected to the workpiece 115, the contact tube 160 and the hot wire power supply 170. The control subsystem 195 is a second control for coordinating or monitoring other aspects of the system and / or hot wire processing such as, for example, a laser subsystem, wire or pool, as described in more detail below. Or a parallel control unit. Accordingly, the exemplary sensing and current control subsystem 195 further provides a resistance (R = V / I) and power value (P =) from the measured voltage and current along with the integral and derivative of the voltage, current and power. It may be possible to calculate V * I). In general, if the hot wire 140 is in contact with the workpiece 115, the potential difference between the hot wire 140 and the workpiece 115 is zero volts or very close to zero volts. As a result, the sensing and current control subsystem 195 can sense when the resistive filler wire 140 contacts the workpiece 115. In addition, as will be described in more detail below along with one or more aspects of the subject start / stop method, the controller subsystem 195 connects to its hot wire power supply 170 in response to sensing. Can be used to control the flow of current through the resistive filler wire 140.

In the exemplary embodiment shown in FIG. 1, system 100 further includes a laser subsystem. The laser subsystem can heat the workpiece 115 with the laser beam 110 focused on the workpiece 115, for example, to maintain a molten pool on the workpiece. The laser subsystem includes a laser device 120 and a laser power source 130 that are operatively connected to each other. The laser power source 130 supplies power for operating the laser device 120. A controller, eg, a second, parallel, state-based controller, as part of or separate from the controller subsystem 195, may be provided to adjust the function of the laser power supply 130. Good. The functions of the laser power supply 130 may include current, voltage or power output, for example, individually in real time or for operation synchronized with the hot wire power supply 170. The laser subsystem may be any type of high-energy laser source, including but not limited to carbon dioxide, Nd: YAG, Yb-disk, YB-fiber, fiber transmission or direct semiconductor laser system. . The laser subsystem is also a wider and higher intensity energy source. Although the high intensity energy source is described as a laser subsystem having a laser beam and a power source, it should be understood that any high intensity energy source can be used. For example, the high intensity energy source can provide at least 500 W / cm ² . Other embodiments of the high intensity energy source include an electron beam that acts 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 arc. It may include at least one of the welding subsystems.

  For welding applications, the laser beam 110 is sufficiently strong in energy to melt some of the base metal of the workpiece 115 and / or melt the wire 140 and drop it onto the workpiece 115. . For the subject method described herein, the laser beam 110 maintains a molten pool in coordination with the state of the filler wire 140. The power source 170 is configured to provide most of the energy required to resistively melt the filler wire 140 for performing hot wire processing. In addition, however, as described herein with respect to certain embodiments, the power supply 170 and the feeder subsystem are more specifically configured to initiate the hot wire process, such as the workpiece 115. Is controlled and operated to initiate the formation of a molten pool in In addition, the power supply 70 and feeder subsystem are configured to finish hot wire processing and prepare for separation of the wire from the molten pool.

  System 100 further includes a motion control subsystem. The motion control subsystem moves the laser beam 110 (energy source) and the resistive filler wire 140 (at least in a relative sense) in the same direction 125 along the workpiece 115, and the laser beam 110 and the resistive filler wire 140. Can remain in a fixed relationship to each other. The relative movement between the workpiece 115 and the laser / wire combination can be achieved by moving the workpiece 115 or moving the laser device 120 and the hot wire feeder subsystem. For example, as seen in FIG. 1, the motion control subsystem includes a motion control unit 180 operatively connected to the robot 190. The motion control unit 180 controls the motion of the robot 190. The robot 190 is operably connected to the workpiece 115 (eg, mechanically fixed) and moves the workpiece 115 so that the laser beam 110 and the wire 140 effectively travel along the workpiece 115. Move in direction 125. According to one embodiment of the present invention, the motion controller 180 may further be operatively connected to the laser power source 130 and / or the sensing and current controller 195. In this manner, motion controller 180 and laser power source 130 may communicate with each other to coordinate activities between the various subsystems of system 100.

  Although FIG. 1 (and FIG. 1A below) illustrates a heat source (laser) upstream of the hot wire in the direction of travel, it should be noted that embodiments of the present invention are not limited in this regard. is there. In particular, the hot wire may enter the pool upstream of the heat source during processing.

  Further, as described previously, although a laser system is shown in FIGS. 1 and 1A, embodiments of the present invention are not limited to the use of a laser system. In particular, as previously described, embodiments of the present invention can also use any one of non-consumable tungsten electrodes or other high energy arcs, or that plasma treatment is used. Can do. For example, in exemplary embodiments of the present invention, laser power supply 130 and laser 120 may be replaced with a GMAW power supply and torch so that a MIG or GMAW process is used to create a molten pool. In such an embodiment, the MIG / GMAW process will create a molten pool and the hot wire process will be performed as disclosed and described herein. For efficiency, the exemplary embodiments described below refer to a laser subsystem. However, this is intended to be exemplary, and the control, integration and operation of the system 100 described herein is similar regardless of the high power energy source that is creating the molten pool.

  Shown in FIG. 1A is a detailed view of hot wire processing at the location of the melt pool 116 on the workpiece 115. More specifically, shown are a laser beam 110 that maintains melt pool 116 and a heated filler wire 140 that is positioned and advanced within melt pool 116. In general, one embodiment of a method for initiating hot wire processing is sufficient to carry filler wire 140 into the vicinity of workpiece 115 and to melt the workpiece therebetween to form molten pool 116. Ready to form an arc. With a stably formed melt pool 116, the current to the wire is reduced to a level that is sufficient to melt or nearly melt the wire, but not to produce an arc between the wire and the workpiece. Is done. Instead, the laser maintains melt pool formation and the wire is advanced into the melt pool to complete the hot wire process. Thus, in one specific aspect of the subject process, a stable transition of wire material to the reservoir 116 is achieved by melting the wire 140 directly into the process, and more specifically, from the wire. Occurs not by the transfer of material into the droplet.

  The stability of the molten pool 116 may be determined by an indirect method. The method may include, for example, feedback of wire speed, voltage or current. More specifically, at the start of hot wire processing, the feeder 150 rises to a desired and known wire feed rate. From the wire feed rate, the amount of wire fed into the pool and the dimensions of the molten pool 116 can be determined. From the amount of wire fed into the pool and the dimensions of the melt pool 116, a desired starting point for initiating hot wire processing can be determined. That is, a desired amount of wire can be added to the melt pool 116 and the pool dimensions can be calculated based on the total wire melted in the pool. For a given puddle size, the puddle is ready for stable hot wire processing. In addition or alternatively, feedback of the actual voltage and / or current output from the power supply can indicate stable stagnation. In a further alternative, historical data or experience regarding the elapsed time for puddle formation may be used.

  As described in more detail below, subject hot wire processing is initiated by an arc between wire 140 and workpiece 116 to form molten pool 117. Thus, in one aspect, hot wire processing is initiated by using a short arc transfer mode or technique between the wire and workpiece for puddle formation. The stability of individual short circuit events, or the time between multiple short circuit events, is an indication of stable pool formation. A stable melt pool 116 is achieved when the arc between the wire 140 and the workpiece 115 is large enough to cause a permanent change in the pool profile (ie, width, thickness, volume, etc.). be able to.

  When the heat input reaches a peak and the minute arc begins, a “flash” of the minute arc can cause ripples in the reservoir. If the pool is large enough, the ripple stops moving in the pool. In one embodiment, the arc strength and / or heat input is so great that the “stopped” material can be blown out of the reservoir and the reservoir is thinned. This individual approach makes the hot wire initiation process independent of speed or other conditions.

  In one other embodiment, hot wire processing and puddle formation may be initiated using a pulse technique with adaptive control. Adaptive control is used, for example, in The Lincoln Electric Company's Pulsed Gas Metal Arc Welding (GMAW-P). Pulse gas metal arc welding is shown and described in the Lincoln electric Waveform Control Technology publication, NX-2.70 (August 2004), entitled "Process: Pulsed Spray Metal Transfer". The publication is incorporated in its entirety by reference. The adaptive control waveform used between the wire and the workpiece indicates the peak voltage or voltage that has been ramped up or the time that the voltage has stabilized or reached the desired value. In a further alternative, a count of the number of pulses or a desired current value may be determined, which may indirectly indicate the wire feed rate and the point at which the pool stabilizes for initiating hot wire processing.

  FIG. 2 illustrates more specifically one embodiment of a start-up method 200 used by the system 100 of FIG. In step 210, a sense voltage is established by the power supply 170. Then, at step 220, the distal end of at least one filler wire 140 is advanced toward the workpiece 115 by the wire feeder 150. In one particular embodiment, the sense voltage is an open circuit voltage (OCV) due to a sense signal applied to the wire 140 by the wire power source 170 under the direction of the control subsystem 195. For example, the sensing and current controller 195 may instruct the hot wire power supply 170 to establish a sensing voltage, eg, an open circuit sensing voltage in the range of 24V to 70V. However, in other exemplary embodiments, smaller sensing voltages may be used. For example, the sensing voltage may be in the range of 3V to 15V. In one other exemplary embodiment, the sense voltage is in the range of 5V to 15V, and in one further embodiment is 5V to 8V.

  The sensing voltage in one particular aspect or embodiment may vary with respect to the type of wire 140. For example, the sensing voltage for the stainless wire may be set within a range of 6V to 9V. At higher nickel wires (having higher resistance), the sense voltage may be set or operated at a slightly higher voltage, ie iron at a slightly lower voltage. Alternatively, for example, if the wire 140 is a larger extruded wire with an outer coating that is not as conductive as the wire core, a suitable sensing voltage outside the range of 5V to 15V is used. Also good. In such a case, the sense voltage may reach 20V. Thus, an appropriate sensing voltage may define a threshold voltage, above which the arc exists between the wire 140 and the workpiece 115, below which the current is reduced or disconnected. And may return to a “hot wire” state or level.

  Further, in exemplary embodiments of the present invention, the applied sensing signal does not provide sufficient energy to appreciably heat the wire 140. One exemplary embodiment of a power source that applies a sensing signal to a filler wire is shown and described in US Patent Publication No. 2010/0176109. The publication is incorporated in its entirety by reference. Of course, in other embodiments, at least some heating may occur while the sensing signal / voltage is applied.

  Referring again to FIG. 2, while the wire is advanced toward the workpiece 115, a change in voltage can be detected if contact is made between the wire 140 and the workpiece 115. Sensing or voltage signals are monitored. As previously described, in some embodiments where the distal end of the wire 140 is spaced from the workpiece 115, the measured OCV is 3 volts or greater. In a first determination step 230 of the starting method, a determination is made as to whether the distal end of the wire has contacted the workpiece 115. Such sensing may be accomplished by sensing a change in OCV as a potential difference between filler wire 140 and workpiece 115, and current controller 195 measures or monitors the change in OCV. When the distal end of the filler wire 140 is shorted to the workpiece 115 (ie, contacts the workpiece), the voltage will drop to or near zero volts. That is, for example, the sensed voltage can drop to or near zero volts when the wire contacts the workpiece. In some exemplary embodiments, until a contact between the wire and the workpiece is established, the starting method repeatedly applies a sensing signal to the wire such that no current flows until the wire touches the workpiece. Be prepared. More specifically, the power supply 170 is turned on at a sense level and the actual voltage between the wire 140 and the workpiece 115 is monitored while the wire 140 is advanced toward the workpiece 115. . The sense voltage or signal is at a level such that only the sense current is within the current flow range when the wire makes contact. Once the wire 140 touches the workpiece 115, there is no “open” circuit voltage, so the monitored voltage is zero. In a further exemplary embodiment, the voltage is monitored to determine if it falls below the touch threshold level. For example, the controller 195 may have a contact detection level of 1 volt, and if the voltage falls below this threshold level, it is determined that contact has been made or is imminent and is described below. Cause further events.

  In step 230, other indirect methods may be used to determine contact between wire 140 and workpiece 115. For example, other contact indicators may include sensing of pressing resistance against the wire.

  Once the wire 140 comes into contact with the workpiece 115, in the retraction step 240, the controller 195 subsequently turns off the sensing signal and retracts the wire from the workpiece. Thus, upon detection of contact with the workpiece, the wire 140 is retracted and the sensing signal is turned off. In some embodiments, the retraction of the wire 140 may be at a constant speed up to a predetermined distance or for a predetermined time. Current is supplied to the wire when the wire retract operation begins. This current may be an arc generating current or a current at a lower level than the arc generating current. As part of the arc forming step 250, the wire 140 begins to retract, creating a gap between the wire 140 and the workpiece 115. When retraction begins, an arc generating current is supplied to the wire 140 by the power source 170. (It is noted that the arc generating current may be supplied shortly before, simultaneously with, or shortly after the wire retracting is initiated.) When the wire 140 is retracted away from the surface, the arc generating current Creates a workpiece between the wire 140 and the workpiece / reservoir.

  In one aspect of the subject method, the arc generating current ranges from about 5 amps to about 30 amps to provide an arc forming voltage between the wire 140 and the workpiece 115. In one other exemplary embodiment, the current ranges from 10 amps to 25 amps. In another aspect, the arc generation current is supplied under a constant current control method between the control unit 195 and the power source 170. In such embodiments, the level of arcing current is predetermined and the power source 170 maintains that current level until such time as an arc is established between the wire 140 and the workpiece 115. The supplied arc current may be supplied using a GMAW short arc or pulse type welding process.

  It should be noted that the arcing current may be applied immediately after the sensing signal is stopped so that the sensing signal is immediately converted to an arcing current. In one other exemplary embodiment, there may be a time difference between the stop of the sensing signal and the arcing signal. While the arcing current is applied, the wire 140 is still retracted until the time when the arc is created and detected. In one exemplary embodiment of the present invention, the voltage between the wire 140 and the workpiece 115 is monitored, and when the voltage reaches the arcing level, the controller 195 has generated an arc. Is to decide. Thus, it is determined that an arc has been created when this arc detection voltage threshold is reached.

  Once the arc detection voltage threshold is reached, indicating the generation of an arc, the retraction of the wire 140 is stopped, a molten pool begins to form, and the wire is advanced again toward the workpiece 115. Thereafter, the wire 140 may be advanced while the puddle begins to form and stabilize. In some embodiments, the time between arc detection and re-advance is in the range of 50 milliseconds to 500 milliseconds. This advance and arc control may be similar to the advance and control used for GMAW short arc or pulse type welding processes. In some exemplary embodiments, the arc is then maintained for a time sufficient to establish a sufficiently sized and stable molten pool while the wire 140 is advanced. For example, in some exemplary embodiments, the arcing current is maintained for a predetermined time after the arc is established. After the passage of time, it is estimated that a molten pool has been created. In one exemplary embodiment, the predetermined time is not longer than 300 milliseconds (ms), and in other exemplary embodiments, the predetermined time is more than 100 ms. Never long.

  In other exemplary embodiments of the start-up method, a second decision step 260 is utilized that monitors the workpiece 115 for the formation of the melt pool 116. In such a step, the surface of the workpiece 115 is monitored to determine whether a melt pool has been created and whether the pool has reached a sufficient size or level of stability. For example, a high speed camera with an electronic shutter may be used to evaluate the pool width. More specifically, a high-speed video camera can be used to observe changes in the reservoir / deposit profile to determine the stability of the reservoir. In one other embodiment, the stability of the molten pool is determined by an indirect method. For example, the power supply 130 monitors the current and / or voltage between the wire 140 and the workpiece 115 during an arc. The voltage and current fluctuate or oscillate until the stagnation stabilizes. Thus, the stability of the stagnation can be indicated by current and voltage stabilization or substantially no vibrations as described above. In such an embodiment, the puddle is monitored until it is satisfactorily determined that a stable melt puddle has been formed. This embodiment of the starting method 200 provides for maintaining an arc between the wire 140 and the workpiece 115. In some exemplary embodiments, a stagnation monitoring technique can be utilized instead of monitoring the arcing voltage level. Either approach can be used on their own (alone) or together to determine when the melt pool is fully created.

  Once it has been determined that a stable melt pool has formed on the workpiece 115 and / or that a certain amount of time has elapsed after the arc has been created, the arcing current is stopped and the wire 140 is melted into the melt pool 116. As it is advanced into the wire, heating power is supplied to the wire 140. The wire is advanced into the pool at the desired wire feed rate. This occurs at step 270. More specifically, once it is determined that the arc between the wire 140 and the workpiece 115 has formed a stable molten pool 116 in the workpiece 115, the retraction of the wire 140 is stopped and in advance step 270a. The wire is advanced into the melt pool 116 again toward the workpiece 115. At the same time, in the wire heating step 270b, a heating current is continuously applied to the wire 140 from the power source 170 or a separate hot wire power source. In one embodiment, the heating current is lower than the arc formation threshold level. In one particular embodiment, the wire heating current is below an arc formation threshold, for example, below 10-20 volts. During hot wire processing, arcs can occur, but hot wire power sources extinguish arcs before they can destabilize hot wire processing. However, the arc heating current is sufficient to heat the wire 140 at or near its melting temperature.

  In the pool maintenance step 270c, a high intensity heat source (eg, laser beam 110 or GMAW arc) is added to the pool to maintain the stability of the melt pool during hot wire processing. In various exemplary embodiments, the beam 110 (or other heat source) can be provided to the reservoir at various times during the initiation process. For example, in some embodiments, the beam 110 can be activated at the beginning of the initiation process, or it can be activated after contact is detected, or it can be after an arc is created. It can be activated or it can be activated after the arcing current has been turned off. The start-up method is completed and the hot wire process 280 is performed by the molten pool 116 being stable and the filler wire 140 being fed into the pool continuously or periodically at or near the melting temperature of the wire. Can. Hot wire processing is shown and described in, for example, US Patent Publication No. 2011/0297658 or US Patent Publication No. 2010/0176109. Each publication is incorporated in its entirety by reference.

  In one alternative embodiment of the start-up method 300 as diagrammatically illustrated in FIG. 3, instead of determining melt pool formation in the second determination step, an alternative method is to establish an established filler wire 140. And determining whether the arc between the workpiece 115 and the workpiece 115 has exceeded a threshold (step). More specifically, an alternative starting method provides for the establishment of a sensed voltage in the first step 310 in the manner previously described. In advance step 320, the distal end of resistive filler wire 140 is advanced toward workpiece 115, and in a first decision step 330, whether the distal end of the wire has contacted workpiece 115. A decision about is made. Again, the distal end of filler wire 140 is shorted to workpiece 115 (ie, contacts the workpiece) and the voltage drops below the contact threshold voltage. Thus, the measured voltage signal is zero or about zero when the wire contacts the workpiece. Until the contact between the wire and the workpiece is determined, the start-up method 300 can establish or maintain and monitor repeated voltage (eg, OCV) while the wire 140 is advanced toward the workpiece 115. I will provide a.

  Similar to the previously described starting method 200, once the wire 140 contacts the workpiece 115, the wire is retracted from the workpiece in the retract step 340, the sensed voltage signal is stopped, and the arcing current is applied to the wire 140. Added. Under the subject method, in the arc forming step 350, the wire 140 is continuously retracted from the workpiece 115, the current is increased and / or an arc is established between the wire 140 and the workpiece 115. Until the formation of the molten pool.

  In one other exemplary embodiment, in a second determination step 360, the arc voltage between the filler wire 140 and the workpiece 115 is monitored and whether the voltage exceeds a threshold, eg, 10-20 volts, Or, more specifically, a determination is made as to whether it is above 15 volts. Additionally or alternatively, the threshold voltage may vary in relation to the type of wire, the material transfer mechanism, such as a short arc or pulse, and / or the shielding gas being used. For example, for a steel filler wire where short arc GMAW technology is used to establish the arc voltage, 15 volts may define the threshold voltage. In steel hot wire processing using GMAW-P to establish an arc, 18-25 volts may be appropriate. The threshold voltage indicates the formation of a stable melt pool 116 on the workpiece 115. For example, the threshold voltage may be of a magnitude that is known to cause an arc under it. Once it is determined that the threshold voltage has been exceeded, the retraction of the wire is stopped and in advance step 370a the wire is advanced again toward the workpiece 115. As the wire is added, a stable pool begins to form and the power source 170 cuts off the arc, allowing the wire to dip into the molten pool 116. At the same time, in a wire heating step 370b, a heating current is applied to the wire 140 to heat the wire 140 at or near its melting temperature. Under the pool maintenance step 370 c, the stability of the melt pool 116 is maintained by application of the laser beam 110 to the melt pool 116. Again, in other embodiments, the laser beam 110 can be activated at various times. By the melt pool 116 being stable and the filler wire 140 being fed into the pool at or near the melting temperature of the wire, the start-up method is completed and the hot wire process 280/380 can be performed. . Hot wire processing 280/380 is performed using the hot wire processing shown and described, for example, in US Patent Publication No. 2011/0297658 or US Patent Publication No. 2010/0176109.

  In this way, in the embodiments described above, the heat of the initial arc is used to create the initial melt pool and start the laser (or arc) hot wire process. It is also desirable to minimize spatter throughout the hot wire process and / or avoid coalescence of filler wires in the molten pool. Accordingly, embodiments of the subject process are hot wire processes where the wire can be removed from the melt pool in a stable manner, for example, without forming an arc between the wire and the workpiece. Including a method of stopping. In general, each of the embodiments of hot wire processing cessation is such that the molten pool is maintained (step) and that the distal end of the wire melts or “burns” out of contact with the molten pool. And heating the wire (step).

  Shown in FIG. 4 is one embodiment of a stopping method 400. Beginning with ongoing hot wire processing, the current termination step 410 provides for terminating or turning off the heating current from the power source 170 to the wire. The heating current may be turned off manually or alternatively may be turned off automatically by sensing and current control subsystem 195. In the particular embodiment of FIG. 4, once the heating current is terminated, the wire supply to the melt pool 116 is reduced in a supply reduction step 420. In one particular embodiment, the speed of wire supply may be stopped. While reducing both the heating current and the wire feed rate (steps) 410, 420, the melt pool is maintained in the maintenance step 430 of at least one embodiment of the subject shutdown process. In a maintenance step 430, the laser beam 110 is applied to the molten pool so as to maintain its stability.

  At the end of the cycle, while the beam 110 is still being applied, the pulse step 440 of the subject method provides for the application of multiple current pulses to the wire 140 to temper or remove the wire 140 from the pool. To do. In one exemplary embodiment of method 400, the sensing and current control subsystem controls power supply 170 to apply a current pulse to the filler wire. The current pulse may be of sufficient magnitude to transfer the wire material into the molten pool, and more specifically to remove the length of the wire from the molten pool. Thus, repeated current pulses are sufficient to “temper” the distal end of the wire out of the molten pool. The exemplary embodiment provides that the current pulse is of a current level that does not initiate an arc between the wire and the workpiece 115. For example, the voltage and / or current may be monitored during the pulse to ensure that the current remains below the arcing level. Alternatively to multiple current pulses, a single current pulse may be used if it has the proper rise time, duration, and current to bake the wire out of the melt pool. Good.

  In some exemplary embodiments, the current pulse is applied until the distal end of the wire 140 exits the melt pool and is fully removed from the pool 116. Thus, in one embodiment, the subject stopping method 400 includes a decision step 450 for determining whether the distal end of the wire 140 is out of the molten pool. For example, the voltage between the distal end of the wire 140 and the workpiece 115 may be continuously monitored during the pulse step 440. Once the monitored voltage exceeds a value indicating separation of the wire from the melt pool, the hot wire current may be terminated at an end step 460. Termination of the hot wire process may include one or more of turning off the power source 170 that is supplying current pulses to the laser and / or wire 140. In other embodiments, the process may be terminated after a predetermined number of current pulses or after the start of a pulse for a predetermined time. In one other embodiment, the wire is removed from the puddle by the end of the pulse and the laser remains activated until the puddle can stabilize from the last drop of the wire. In one other embodiment, the laser is lowered to slow down the “crater” or indentation left by the drawn wire and slow down the solidification of the pool.

  One other embodiment of a method for stopping hot wire processing is shown in FIG. In this stopping method, the filler wire supply is stopped or alternatively withdrawn from the molten pool and the heating current is still applied to the wire 140 during the withdrawal. The current to the wire and / or the voltage between the wire and the workpiece is monitored for the occurrence of arcing between the distal end of the wire and the workpiece. The heating current to the wire is terminated immediately before the arc is formed, and the hot wire process is terminated.

  More specifically, FIG. 5 shows hot wire processing in progress. In step 510a, the wire supply to the molten pool is stopped manually or by automatic control of the wire feeder 150. Alternatively, the process may include a retraction step 510b. In the retreat step 510 b, the wire feeder 150 is operated to retract the filler wire 140 from the molten pool 116. In either step, the heating current is maintained. In some exemplary embodiments, the heating current is maintained but maintained at a level lower than the heating current level during hot wire processing. For example, the reduced heating current is 90% or less than 90% of the hot wire process preceding the reduction. In maintenance step 520, the molten pool is maintained in a stable state by a separate high intensity energy source, such as laser beam 110.

  The wire supply is stopped and / or the wire 140 is retracted from the melt pool 116 and the heating current to the wire is monitored in a monitoring step 530 and an arc is generated between the distal end of the wire 140 and the workpiece 115. A decision step 540 is performed to determine if it is about to form. Alternatively or additionally, the monitoring step may include monitoring the voltage between the wire 140 and the workpiece 115. In one particular embodiment, the determining step may be performed by a premonition circuit of system 100. The predictive circuit described above can determine whether an arc is about to form between the workpiece / melt pool and the distal end of the wire 140 by monitoring current and / or voltage evaluation.

  Prediction circuits are well known in the art relating to arc welding and may be implemented in system 100 and / or controller 195 and / or power supply 170. For example, one exemplary embodiment of the predictive circuit of the system 100 may be configured in the sensing and current controller 195, the potential difference (dv / dt) between the filler wire 140 and the workpiece 115, filler Of the current through the wire 140 and the workpiece 115 (di / dt), the resistance between the filler wire 140 and the workpiece 115 (dr / dt) or the power through the filler wire 140 and the workpiece 115 (dp / dt) One or more of the speeds of one change may be measured. If the rate of change exceeds a predetermined value or threshold, the sensing and current controller 195 predicts or interprets from measurements that a loss of contact is about to occur. More specifically, if the distal end of the wire 140 is highly melted by heating, the distal end may begin to constrict from the wire 140 onto the workpiece 115. If contact between the wire and the workpiece is completely lost, an appreciable potential difference (ie, voltage level) greater than zero volts can be measured by the sensing and current controller 195. This potential difference can cause an arc to form between the new distal end of wire 140 and workpiece 115. Thus, the rate of change of voltage between the wire and the workpiece may be monitored for its proximity to a known threshold that the arc is known to form. Alternatively, the current level, resistance level in the wire, and / or power level to the wire may be monitored to determine a point in time prior to arc formation. For example, the isolation voltage and / or current level can be utilized to determine if isolation has occurred or will occur, and if this level is reached or exceeded, the wire 140 will accumulate 116. Determined to be separated from Alternatively, this level may be an arc generation level (voltage, current, power, etc.) that detects impending arc generation as a detection of separation.

  Once a determination is made that an arc is just forming between the wire 140 and the workpiece 115 and / or that the wire 140 has detached from the pool 116, in the current termination step 550, the heating current to the wire is It will be terminated. Once the monitored voltage exceeds a value indicative of the separation of the wire from the melt pool, at end step 560, hot wire processing may be terminated. Because the stop process 500 proceeds to a point just prior to arc formation between the wire 140 and the workpiece 115, the distal end of the wire is positioned outside the melt pool 116 when the heating current is terminated. The hot wire process is completely terminated at step 560 when the laser power source 130 is turned off.

  FIG. 6 is another embodiment of the stopping method 600. Beginning with the ongoing hot wire process, the stop motion step 610 provides for stopping the relative movement between the workpiece 115, the laser 120 and / or the wire 140 (step). In the particular embodiment of FIG. 6, once the relative movement is terminated, the rate of wire feed to the melt pool 116 is reduced and / or stopped in a feed rate reduction / stop step 620. Reducing / stopping both relative motion and feed rates between the components of the system (steps) 610, 620, maintaining step 630 of at least one embodiment of the subject stopping process. At this point, the molten pool 116 is maintained. In a maintenance step 630, the laser beam 110 is applied to the molten pool so as to maintain its stability.

  At the end of the cycle, while the beam 110 is still being applied, the pulse step 640 of the subject method provides for the application of a heating current to the wire 140. In one exemplary embodiment of method 600, control subsystem 195 controls power supply 170 to apply a heating current to filler wire 140. Simultaneously or subsequently, in retract step 650, the wire is retracted from melt pool 116 to a point where the wire breaks from the pool. In one particular embodiment of the method 600, a predictive circuit is used and the wire may be heated (640), retracted (650), and released at a known point. As the wire 140 leaves, the wire extension may remain extended from the melt pool 116. Laser 120 and beam 110 bake extensions extending from melt pool 116. Termination of hot wire processing may include one or more of turning off the laser and / or power 170 at step 670.

  As previously mentioned, embodiments of the present invention can be utilized with a GMAW / MIG system instead of a laser. A GTAW type system can also be used to provide high intensity heat, as described herein. When utilizing GMAW / MIG processing, the start and stop steps are generally as described herein. In some exemplary embodiments, as described above, a GMAW / MIG / GTAW is initiated (arc is initiated) prior to arc initiation in hot wire processing. In such an exemplary embodiment, a GMAW / MIG / GTAW arc is initiated and the arc is advanced so that a molten pool is formed. Thereafter, the hot wire start process is started. In other embodiments, it may be beneficial to start the hot wire process shortly before the start of the GMAW / MIG / GTAW arc. However, the delay should not be too long so that once the GMAW / MIG / GTAW arc generation has begun, hot wire processing can begin at the appropriate time.

  1 and the above description of the system 100 provides a general component description of the system for performing any of a plurality of subject start and / or stop methods for hot wire processing. U.S. Patent Application Publication No. 2011/0297658, U.S. Patent Application Publication No. 2010/0176109 describes a system 100 for performing a subject start and / or stop method and associated hot wire processing. Alternative or additional embodiments. Each of these applications is incorporated by reference in its entirety.

  Although the invention has been described with reference to certain embodiments, it will be appreciated by those skilled in the art that various changes can be made and equivalents can be substituted without departing from the scope of the invention. Will be understood. 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 thereof. Accordingly, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention include all embodiments that fall within the scope of the appended claims.

100 System 330 Determination Step 110 Laser Beam 340 Retraction Step 115 Workpiece 350 Formation Step 116 Puddle 360 Determination Step 117 Puddle 370a Advance Step 120 Laser Device 370b Heating Step 125 Direction 370c Maintenance Step 130 Power Supply 380 Process
140 Filler wire 400 Stopping method 150 Wire feeder 410 Ending step 160 Contact tube 420 Reduction step 170 Power source 430 Maintenance step 180 Control unit 440 Pulse step 190 Robot 450 Determination step 195 Control subsystem 460 Ending step 200 Start-up method 500 Stop step 210 Step 510b Retraction step 220 Step 520 Maintenance step 230 Determination step 530 Monitoring step 240 Retraction step 540 Determination step 250 Formation step 550 Termination step 260 Determination step 560 End step 270 Step 600 Stop method 270a Advance step 610 Movement stop step 270b Heating Step 630 Maintain step 270c Maintain step 620 Reduce / stop step Flop 280 step 640 (pulse) step 300 starting method 650 backward step 310 the start step 670 the termination step 320 step forward

Claims (15)

A method of initiating hot wire processing, the method comprising:
Establishing an arc between the filler wire and the workpiece so as to form a molten pool in the workpiece;
Applying heat to the molten pool by a high intensity energy source different from the arc;
Advancing the wire into the melt pool after establishing the arc; and applying a heating current to the wire to terminate the arc and melt the wire into the melt pool ,
Including a method.   The method of claim 1, wherein the high intensity energy source is a laser.   The method of claim 1 or claim 2, further comprising sensing contact between the wire and the workpiece prior to establishment of the arc. Sensing the contact comprises:
A sub-step of advancing the wire toward the workpiece; and a sub-step of applying a sensing signal to the wire to determine contact between the wire and the workpiece;
including,
The method according to claim 1. Establishing the arc includes substeps of retracting the wire from the workpiece and substep of applying an arcing current to the wire during retraction to establish the arc; or The arc is established after the sensing signal in the filler wire drops below a threshold when the filler wire contacts the workpiece.
5. A method according to any one of claims 1 to 4. Establishing the arc includes a sub-step of applying an arc-generating current and a sub-step of providing a gap between the workpiece and the wire;
The arc generating current has sufficient energy for the arc to be strong enough to form a molten pool in the workpiece;
The method according to any one of claims 1 to 5. Further comprising the step of stopping the hot wire process, the step comprising:
A sub-step of stopping the heating current to the wire;
A sub-step of reducing the feed rate of advance of the wire into the melt pool of the workpiece;
Maintaining the molten pool by the high intensity energy source;
Applying a plurality of current pulses to the wire such that a distal end of the wire is removed from the melt pool;
And / or
Further comprising the step of stopping the hot wire process, the step comprising:
A sub-step of stopping advancement of the wire into the melt pool of the workpiece;
A sub-step of retracting the wire from the melt pool;
Maintaining the molten pool by the high intensity energy source;
A sub-step of sensing the formation of an arc between the wire and the workpiece; and a sub-step of terminating a heating current to the wire before the arc is formed;
And / or
Further comprising the step of stopping the hot wire process, the step comprising:
A sub-step of stopping the advance of the wire into the molten pool;
Substeps of retracting the wire from the melt pool such that at least some of the heating current applied to the wire causes the wire to leave and separate from the melt pool and leave a wire extension in the melt pool; And sub-steps of applying energy from the high intensity energy source so as to melt the extension into the melt pool;
including,
The method according to claim 1.   8. Establishing the arc between the wire and the workpiece includes the sub-step of applying current to the wire using one of a short arc transfer welding process or a pulse welding process. The method as described in any one of.   9. A method according to any one of the preceding claims, further comprising stabilizing the molten pool with the arc.   10. A method according to any one of the preceding claims, further comprising monitoring the arc to determine the stability of the melt pool. A hot wire system,
A feeder for advancing and retracting the distal end of the filler wire relative to the workpiece;
A power source for applying a sensing signal, arcing current and heating current to the wire;
A controller coupled to the feeder and the power source for initiating hot wire processing, wherein the controller positions the wire relative to the workpiece, the sensing signal, the arc generation signal, and the heating; Each of the currents is controlled,
Advancing the distal end of the wire toward the workpiece and adjusting the sensing signal to determine when the distal end is in contact with the workpiece;
Retreating the distal end of the wire from the workpiece and adjusting the arcing current so that an arc is formed between the distal end and the workpiece to form a molten pool. Advancing the wire into the melt pool and adjusting the heating current so as to melt the wire into the melt pool;
A control unit, and a high-intensity energy source for applying heat to the molten pool,
Having a hot wire system.   The hot wire system of claim 11, wherein the controller includes a prediction circuit for determining a moment prior to arc formation between the wire and the workpiece. The high intensity energy source is a laser and the controller is operably connected to the laser to coordinate the operation of the laser with the power source; or
The high-intensity energy source is an arc generator, and the controller is operably connected to the arc generator to link the operation of the arc generator with the power source.
The hot wire system according to claim 11 or 12. A hot wire system,
A feeder for advancing and retracting the distal end of the filler wire relative to the melt pool of the workpiece;
A power source for applying current to the wire;
A high intensity energy source for applying heat to the molten pool, and a control unit coupled to the feeder and the power source to stop hot wire processing, the control unit connecting the wire to the workpiece Positioning and controlling the current, the current control is
(I) stopping the advance of the wire into the melt pool and pulsing the current to the wire to bake out the wire from the pool;
(Ii) retracting the wire from the melt pool and adjusting the current to prevent arcing between the wire and the workpiece; and (iii) retracting the wire from the melt pool; The wire can leave the melt pool without causing an arc between the wire and the workpiece, and heat from the high intensity energy source can melt a portion of the wire extending from the pool. Adjusting the current to the wire,
A control unit including at least one of
Having a hot wire system. A method of stopping a hot wire process in which a filler wire is melted in a molten pool of a workpiece by heating current,
Reducing the feed rate of the wire into the melt pool;
Maintaining the molten pool with a high intensity energy source; and (i) stopping the heating current to the wire; and a plurality of current pulses such that the distal end of the wire is removed from the molten pool Adding to the wire;
(Ii) retracting the wire from the melt pool, sensing the formation of an arc between the wire and the workpiece, and terminating a heating current to the wire before the arc is formed. ,
(Iii) The wire is retracted from the melt pool such that at least a portion of the heating current applied to the wire leaves and separates the wire from the melt pool to leave a wire extension in the melt pool. Applying energy from the high intensity energy source to the wire extension so as to melt the extension into the melt pool;
At least one of the
Including a method.

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