ADDITIVE MANUFACTURING MACHINE

An additive manufacturing machine that includes a wire supply including a wire drive configured to advance a wire at a wire feed rate and a wire heater configured to apply resistive heating to heat the wire. The additive manufacturing machine includes an additive head for emitting a laser beam to weld the wire to a substrate, a sensor configured to detect a weld parameter, and a controller operatively connected to the wire supply, additive head, and sensor. The controller is configured to determine a failure mode of the weld as the laser beam welds the wire to the substrate based at least in part upon the weld parameter. In response to determining the failure mode, the controller is configured to adjust at least one of the wire feed rate, the resistive heating, and a power of the laser beam as the laser beam welds the wire to stabilize the weld.

FIELD

This disclosure relates to machine tools and, more specifically, relates to machine tools having additive and subtractive capabilities.

BACKGROUND

Hybrid machine tools are known that permit different types of operations to be performed on a workpiece. For example, some hybrid machine tools facilitate production of a part using additive manufacturing and machining of the part using machine tools. The additive manufacturing operation utilizes a laser that is directed at a bed of particles to fuse the particles together and form the part.

SUMMARY

In one aspect of the present disclosure, an additive manufacturing machine is provided that includes a wire supply including a wire drive configured to advance a wire at a wire feed rate and a wire heater configured to apply resistive heating to heat the wire. The additive manufacturing machine includes an additive head for emitting a laser beam to weld the wire to a substrate, a sensor configured to detect a weld parameter, and a controller operatively connected to the wire supply, additive head, and sensor. The controller is configured to determine a failure mode of the weld as the laser beam welds the wire to the substrate based at least in part upon the weld parameter. In response to determining the failure mode, the controller is configured to adjust at least one of the wire feed rate, the resistive heating, and a power of the laser beam as the laser beam welds the wire to stabilize the weld. The additive manufacturing machine monitors the welding process via the sensor to detect deviations from a stable welding process and adjusts the wire feed rate, the heater electrical power, and/or the laser power to take corrective action and stabilize the welding procedure. The additive manufacturing machine may thereby dynamically control the operation of the additive head as the additive head welds the wire to the substrate to ensure the additive head builds a workpiece having a predetermined geometry.

In one embodiment, the failure mode determined by the controller comprises any one or more of a plurality of predetermined failure modes including excessive arcing, non-linear wire feed, sagging of an additive surface, and inadequate bead penetration into the substrate. The controller may determine the failure mode upon the weld parameter approaching an upper or lower threshold for the weld parameter or determining the weld parameter has deviated beyond a threshold for the weld parameter, as some examples. In some situations, the controller may determine two or more failure modes are occurring simultaneously during the welding process and may adjust the wire feed rate, heater electrical power, and/or laser power to address the failure modes.

The present disclosure also provides a hybrid machine tool comprising a spindle head configured to receive and rotate a tool for machining a workpiece having predetermined dimensions prior to machining thereof. The hybrid machine tool has a wire supply including a wire drive configured to advance a wire at a wire feed rate and a wire heater configured to apply resistive heating to heat the wire. The hybrid machine tool further includes an additive head for emitting a laser beam to weld the wire to a substrate and form the workpiece. A controller is operatively connected to the spindle head, wire supply, and the additive head. The controller is configured to adjust any of the wire feed rate, the resistive heating, and a power of the laser beam as the laser beam welds the wire to form the workpiece having the predetermined dimensions so that the workpiece can be precisely machined by operation of the spindle head. The controller is also configured to operate the spindle head to machine the workpiece having the predetermined dimensions via rotation of the tool. The ability of the controller to adjust any of the wire feed rate, the resistive heating, and the power of the laser beam enables the hybrid machine tool to provide a workpiece to be machined by the spindle head that has the desired dimensional and metallurgical properties needed to machine the workpiece into a part having predetermined final part properties with an accuracy of a few ten-thousandths of an inch. For example, by controlling the welding as the laser welds the wire to the substrate, the net geometry, tool life, and surface finish associated with machining the workpiece can be precisely controlled.

In another aspect of the present disclosure, a hybrid machine tool is provided that includes a spindle head, a wire supply to advance a wire toward a substrate, an optical head configured to emit a laser beam to weld the wire to the substrate, and a frame assembly configured for supporting the spindle head and the optical head for being driven along multiple transverse axes including an X axis. The frame assembly is configured for supporting the spindle head to be driven along a Y1 axis perpendicular to the X axis and along a Z1 axis perpendicular to the X axis and the Y1 axis. The frame assembly is configured for supporting the optical head to be driven along a Y2 axis parallel to the Y1 axis and perpendicular to the X axis independently of driving the spindle head along the Y1 axis. Further, the frame assembly is configured for supporting the optical head to be driven along a Z2 parallel to the Z1 axis and perpendicular to the X axis and the Y2 axis independently of driving the spindle head along the Z1 axis. The spindle head and the optical head have respective bodies with the spindle head body larger than the optical head body at least along the Y1 and Y2 axes and the Z1 and Z2 axes with the independent driving of the optical head relative to the spindle head along Y2 and Z2 axes allowing the optical head to be driven farther distances along the Y2 and Z2 axes than the spindle head is driven along the Y1 and Z1 axes, respectively. For example, the optical head may be independently driven along the Z2 axis 1.5 meters whereas the spindle head may be limited to a travel in the Z1 axis of a shorter, 800 cm distance due to size of the body of the spindle head.

The hybrid machine tool also includes a controller operatively connected to the spindle head, wire supply, optical head, and frame assembly and being operable to cause the optical head to be selectively driven along the multiple axes for producing a workpiece via the optical head welding the wire. Further, the controller is operable to rotate the spindle for machining the workpiece with the tool.

The present disclosure also provides a hybrid machine tool having a spindle head, a wire supply to advance a wire, and an additive head configured to emit a laser beam to weld the wire to a substrate. The hybrid machine tool further includes an air source, a shield gas source, a valve, and a controller. The valve has a first configuration wherein the valve directs air from the air source toward the additive head to protect the additive head from debris produced during machining of the workpiece and a second configuration wherein the valve directs shield gas from the shield gas source toward the additive head to provide a predetermined atmosphere for welding the wire. The controller is configured to shift the valve from the first configuration to the second configuration upon operation of the additive head. The shield gas provides an inert medium around the welding area to improve the welding process including limiting oxygen in the welding area, such as limiting the welding area to less than 2% free oxygen concentration. The controller shifts the valve from the second configuration to the first configuration upon a termination of the operation of the additive head. With the valve in the second configuration, the air provided to the additive head creates a higher air pressure area of the additive head than the surrounding environment which resists ingress of debris (such as millings) from operation of the spindle head into the additive head.

In another aspect of the present disclosure, a hybrid machine tool is provided that includes a spindle head, a temperature sensor to measure a temperature of a substrate, a wire supply to provide a wire, and an additive head configured to emit a first laser to weld the wire to a substrate. The substrate may be, for example, a base material secured to a table of the hybrid machine tool or a layer of previously-welded wire. The hybrid machine tool further includes a controller configured to determine whether the temperature of the substrate is at a target temperature based on the temperature of the substrate measured by the temperature sensor. Upon the temperature of the substrate not being at the target temperature, the controller adjusts the additive head to emit a second laser having a greater diffusion on the substrate than the first laser. The controller is further configured to cause the additive head to emit the second laser and heat the substrate to the target temperature. Because the hybrid machine tool may heat the substrate using a diffused laser from the additive head, the hybrid machine tool allows an operator to raise the temperature of the substrate to a temperature that may be desirable for welding by using the diffused laser rather than requiring the operator to heat the substrate in an oven and position the heated substrate in the hybrid machine tool.

The present disclosure also provides a method of heating a substrate using a hybrid machine tool having a spindle head and an additive head. The method includes measuring a temperature of a substrate and determining whether the substrate is at a target temperature. The method further includes adjusting the additive head to emit a diffused laser at the substrate upon the temperature of the substrate not being at the target temperature. The method further comprises causing the additive head to emit the diffused laser to heat the substrate. Further, the method includes causing the additive head to emit a welding laser that has a reduced diffusion on the substrate than the diffused laser to melt the substrate once the substrate has reached the target temperature. The method permits the hybrid machine tool itself to raise the temperature of the substrate to a temperature suitable for welding the wire to the substrate.

DETAILED DESCRIPTION

With respect toFIG. 1, a hybrid machine tool10is provided that includes a tool enclosure12and an additive system enclosure14. The hybrid machine tool10has a vertical column16that includes a spindle head18and an additive head20(seeFIG. 4). The hybrid machine tool10receives CNC programming, for example, via EIA/ISO programming such as MAZATROL® programming language, representative of a final part geometry. The additive head20utilizes hot wire welding to form a workpiece having an intermediate or additive net geometry by welding a heated wire to a substrate. The wire may include one or more metallic materials, such as ferrous and non-ferrous metals. Example metallic materials include steel, stainless steel, aluminum, titanium, invar, and/or inconel. The wire may be a composite material such as metallic material and a superhard material dispersed therein, such as tungsten carbide in particulate form. The additive head20progressively builds the part by welding the wire to an initial substrate, then progressively welding layers of the wire onto one another with each previous layer of the wire acting as a working substrate to which the current layer is welded. The CNC programming representative of the final part geometry may include slicing the final part geometry into layers that are progressively deposited by the additive head20to form the additive net geometry. The additive head20may utilize commercially available welding wire and is capable of depositing approximately 2.22 kg/hour with a material utilization rate of approximately 98%, which provides an economical and rapid approach for producing large parts.

The additive head20may be operated to produce a part having a somewhat coarse geometry. The hybrid machine tool10may then utilize one or more tools received in the spindle head18to machine the finished part from the workpiece with a high accuracy final geometry. The hybrid machine tool10is also operable to interleave additive and subtractive processes to produce parts having complex geometries while limiting the use of long tools. Long tools may need to be stronger to resist the loading applied during machining and as a result may be more expensive than a corresponding shorter tool. For example, the hybrid machine tool10may operate the additive head20to print a component having a hole. The additive head prints the component in 2 cm layers. After printing each 2 cm layer, the hybrid machine tool10then operates the spindle head18so that a tool received therein machines a portion of the hole portion in the 2 cm layer. The portion of the hole in each layer is aligned with the portion of the hole in the previous layer. The hybrid machine tool10may thereby progressively form a part having a deep precision hole while using a 2 cm cutter. Other benefits of the interleaving process may include decreased cycle time, better geometric control of internal features, and eliminated necessity of custom tooling or fixtures.

Referring toFIG. 1, the tool enclosure12includes a housing22that encloses a work room24and a door26that is movable between open and closed positions to facilitate access to the work room24. The hybrid machine tool10has a table30for supporting a part during both the additive and subtractive processes. A fixture is used to secure the part to the table30.

Referring toFIG. 2, the hybrid machine tool10has a hot wire welding apparatus40that includes the additive head20. The hot wire welding apparatus40includes an optical head42of the additive head20that emits a laser beam44. In one embodiment, the optical head42is a component of a fiber laser. A fiber laser utilizes laser light created by diodes that is channeled and amplified in fiber optic cable which may be doped in rare-earth elements. The amplified light is collimated and focused by one or more lenses onto the target material. An example of a suitable optical head is a 200 MMFL Fibermini 2.0 sold by Laser Mechanisms, Inc. The optical head42may be capable of being used as a cutting laser, if so configured. The optical head42is the torch of the hybrid machine tool10, with the optical head42providing final collimation, focus, and emission of the laser beam.

RegardingFIG. 2, the hot wire welding apparatus40further includes a laser resonator46to generate the laser and a wire supply47to provide wire to the additive head20. In one embodiment, the wire supply47includes a wire spool or roll48for supplying wire50, a wire feeder52, and a wire feeder54of the additive head20. The wire feeder52pays out the wire50from the wire roll48, such as by pushing the wire50off of the wire roll48, and then the wire feeder54pulls the wire50down through conduit212into a guide56connected to the optical head42. The guide56orients and directs the wire50such that an end portion58of the wire50is advanced into a puddle or melt pool60in a bead62. As shown inFIG. 2, the laser beam44is directed toward a base material or substrate70and forms the melt pool60by melting the substrate70. The wire50is advanced into the melt pool60wherein the wire50melts and mixes with the substrate70. As the optical head42is moved in direction64, the wire50is welded to a substrate70which forms the bead62. The bead62cools and hardens as the optical head42moves in direction64.

Continuing reference toFIG. 2, the hot wire welding apparatus40includes a wire heating power source64that provides power to the wire feeder54so that the wire feeder54also heats the wire50. The wire50is a metallic material, such as steel alloys, bronze, aluminum, titanium, stainless steel, duplex steel, and nickel-based alloys. The wire50utilized for a particular part may have a diameter selected for the part, such as approximately 0.035 inch, 0.045 inch, or 0.063 inch diameter. As an example, a deposition utilizing approximately 0.045 inch wire produces a deposition height of approximately 1.2 mm for each layer. The wire heating power source64and wire feeder52heat the wire50using electrical resistive heating to a plastic state, wherein the wire has a more pliable consistency as the wire50is advanced toward the melt pool60. More specifically, the wire heating source64and/or the wire feeder54apply a current and a voltage to the wire50, and the resistance to the flow of electricity through the wire50generates heat which heats the wire. The table30is operatively connected as a process return lead for the wire heating source64such that electricity travels through the wire50to the table30. The electricity flowing through the wire30to the table30and back to the wire heating source64is isolated from the rest of the electrical systems of the hybrid machine tool10. The wire50is heated so that the wire50approaches the melting temperature of the wire50to readily conform to and adhere to the substrate during the additive process. The hot wire welding apparatus40provides a preheat zone51wherein the wire50is raised to a temperature suitable for welding and a deposited zone53wherein the wire50has been welded to the substrate70. In one approach, the wire50has a consistency resembling toothpaste when the wire50is in the preheat zone51and is advanced into the melt pool60. The wire in the preheat zone51is heated by the resistive heating as well as the heat from the welding process. The wire50may be relatively solid upstream of the preheat zone51so that the wire50may be advanced by the wire feeder54in the additive head20toward the laser beam44.

The hybrid machine tool10includes a controller80having a processor82, a memory84, and communication circuitry86. The memory84is a non-transitory computer readable medium and stores instructions that, when executed by the processor, cause the processor82to perform operations as discussed herein. The communication circuitry86facilitates interfacing of the processor82with various components such as a sensor. For example, the hybrid machine tool10may include one or more optical sensors, such as a camera90, one or more sound sensors, such as a microphone92, and one or more thermometers such as thermometers270,272,274,276(seeFIG. 9) as discussed below. In one example, the processor82includes one or more microprocessors, the memory84include volatile and/or non-volatile memory (e.g., electro-mechanical data storage, EEPROM, RAM, NAND flash memory), and the communication circuitry86includes a Wi-Fi® network interface, a Bluetooth® interface, and/or a wired ethernet connection.

In one embodiment, the camera90is a thermal imaging camera. The processor82utilizes data from the camera90to determine a temperature and/or a size of the melt pool60, temperature of the bead62, and/or the temperature of the end portion58of the wire50, as some examples. The processor82may operate the camera90to detect arcing as well as the color of the light emitted by the hot wire welding process.

The microphone92may detect sounds associated with the hot wire welding process that are indictive of the properties of the process. For example, the processor82may utilize data from the microphone92to detect crackling, inconsistencies, or sharp changes in the sound emitted by the hot wire welding process. As discussed in greater detail below, the processor82may utilize data from the camera90and microphone92to identify issues with the hot wire welding process and adjust parameters of the process as needed.

The hybrid machine tool10is configured to be connected to an inert gas source100for providing a shield or inert gas, such as argon, to a welding area101(seeFIG. 2) at the weld site. The hybrid machine tool10provides an oxygen content in the welding area encompassed by the shield gas that is below 1% free oxygen concentration. The hybrid machine tool10is also configured to be connected to an air source102for providing clean, dry air. The hybrid machine tool10has a cover lens assist gas circuit99including a valve, such as one or more solenoids104, configured to place the inert gas source100or the air source102in communication with the optical head42. In one embodiment, the solenoid104includes an air solenoid104A and a gas source solenoid104B. The operation of the solenoid104may be controlled by the processor82such that when the additive head20is active, the solenoid104permits the inert gas source100to direct the argon gas to the optical head42and the welding area101. When the hot wire welding process has stopped, the processor82operates the solenoid104to direct air from the air source102, such as a compressed air shop line, to the optical head42. The air source102may be configured to create a positive air pressure proximate to a cover lens106of the optical head42. The positive air pressure near the cover lens106keeps dust, metal shavings, and other debris away from the cover lens106which prolongs the life of the cover lens106. In one embodiment, the cover lens assist gas circuit99directs the clean, dry air into a compartment177above the cover lens106. The air provided into the compartment177creates a high pressure area that resists ingress of debris into a compartment175(seeFIG. 4) of the additive head20. The cover lens106may be relatively close to the machining operation due to the proximity of the optical head42to the spindle head18, such that the positive air pressure near the cover lens106protects the cover lens106and may reduce the frequency of needing to replace the cover lens106.

Referring toFIG. 3, the hybrid machine tool10has a frame assembly110including a base frame112, an intermediate frame such as a saddle114, and head frame such as the column16. The hybrid machine tool10has a large base116supporting the housing28and the base frame112. The saddle114and base frame112have one or more slide connections therebetween, such as linear guides120, that permit movement of the saddle114along a horizontal X-axis122. The column16and saddle114have one or more slide connections therebetween, such as linear guides124that permit movement of the column16, and the spindle head18and additive head20thereof, along a horizontal Y-axis126. The hybrid machine tool10includes a saddle drive130in communication with the processor128and operable to drive the saddle114along the X-axis122. The hybrid machine tool10further includes a column drive132configured to drive the column132along the Y-axis126. The saddle drive130and column drive132may each include one or more motors and transmission components to effect movement of the saddle114and the column16.

Referring toFIG. 3, the table30includes a table drive32and a table top140. The table top140includes an upper surface for supporting an initial substrate and one or more mounting portions, such as openings in the table top140, for mounting the initial substrate to the table top. The table drive32includes one or more motors to effectuate movement of the table top140. The table drive32is operable to drive the table top140in rotary directions about a B-axis142and a C-axis144perpendicular to the B-axis.

Referring toFIG. 4, the column16includes a column frame150. The spindle head18and additive head20are slidably connected to the column frame150such as by linear guides152so that each of the heads18,20are independently slidable relative to each other. The column16includes a spindle head drive154operable to shift the spindle head18along a vertical Z1-axis156and an additive head drive160operable to shift the additive head20along a vertical Z2-axis162. The vertical Z1 and Z2 axes156,162are orthogonal to the horizontal X and Y axes122and126. The spindle head18has a body167that is larger than a body203(seeFIG. 7) of the optical head42along the Y1, Y2 axes and the Z1, Z2 axes. The spindle head18including a motor169operable to rotate a spindle170of the spindle head18about the Z1-axis156. The large body167of the spindle18provides rigidity and inertia to provide precise machining using the spindle head18. In one embodiment, the spindle170includes a collet for receiving a tool. The additive head20directs the laser44along the Z2-axis162. The spindle head18and additive head20are positioned side-by-side on the column frame150. There is a lateral offset164between the Z1-axis156of the spindle head156and the Z2-axis162of the additive head20.

In one embodiment, the drives130,132,154,160of the frame assembly110include ball screws with servomotors and encoders. The drives permit accurate relative shifting of the components of the frame assembly along respective axes.

The additive head10includes a cover171and an actuator173operably coupled to the controller80. The actuator173is configured to remove the cover171from a closed position when the additive head20is inactive to an open position when the additive head20is active. The cover171helps protects the components of the additive head20, such as cover lens106, from dust, metal millings, and other debris.

With reference toFIG. 5, the additive head20includes a housing170, an optical assembly172including the optical head42, and a wire feeder54. The wire feeder54includes one or more roller assemblies180that are controlled by the processor82to advance the wire50to the guide56for the wire50at a distal end portion182of the additive head20.

Referring toFIG. 6, the wire feeder54includes the drive roller assemblies180and a wire feed guide tube184. The housing170has a forward tubular portion186having a polygonal, e.g. square, cross-sectional configuration with one of the sides thereof including an access door188for closing an opening190in the forward tubular portion186and permitting access to the optical assembly172. The additive head20further includes a removable tray assembly192having a tray194for supporting the optical head42. The removable tray assembly192is slidably received in a rear channel196of the forward tubular portion186for being slid forward therealong so that the optical head42is disposed in the forward tubular portion186.

Referring toFIG. 7, the additive head20includes a lock200having a solenoid201operably coupled to the controller80. The lock200has a locked configuration that inhibits separation of the components202of the optical head42that must be separated to access the cover lens106of the optical head42. Upon an instruction from a user, the controller80may cause the solenoid201of the lock200to shift to an unlocked configuration which permits separation of the components202when the hybrid machine tool10is inactive and the air source102is turned off. In this manner, the lock200keeps the user from replacing the cover lens106while the air source102is turned on which, in turn, inhibits the air source102from blowing debris in the workroom24into contact with the optical head42.

Continuing reference toFIG. 7, the removable tray assembly192includes a distribution terminal block210, a wire conduit212, a shield gas conduit214, thermometer276, a band clamp218, and a sleeve220for securing a shroud224to an outlet tube226of the optical head42. The wire conduit212for the wire50connects to the guide56by way of a fitting230. The removable tray assembly192further includes an insulating plate232and a slide plate234. The insulating plate232isolates the hot wire welding system electrically from the rest of the machine. Slide plate234is a crosslide assembly, used to position the wire feed location by adjusting the position of the guide56. The slide plate234is manually adjustable to set the wire feed location during machine setup or for troubleshooting, as some examples.

Referring toFIG. 8, the distal end portion182of the additive head42includes an adapter240having an annular configuration to connect the outlet tube226of the optical head42to an aperture tube242. The aperture tube242fits through a central opening246of a laser nozzle cooling block248. The distal end portion182of the additive head20further includes an annular nozzle retainer250configured to be threadingly engaged with an annular flange252of the contact block248. The distal end portion182further includes the guide56that connects to the conduit fitting230and a shield gas fitting such as an elbow254. The elbow254receives shield gas via the shield gas conduit214and includes an outlet for shield gas, such as a diffuser256having a plurality of openings therein. The elbow254fits in an opening258of the contact block248and is connected thereto. The guide56has a fitting portion260with a plurality of flats, the fitting portion260sized to fit through an opening262of the contact block248.

Referring toFIG. 9, the additive head20includes a plurality of thermal sensors, such as a thermometer270, a thermometer272, a thermometer274, and the thermometer276. The thermometers270,272,274,276each include one or more thermistors, as one example. The thermometer270detects a temperature of a laser collimator280of the optical head42and the thermometer272detects a temperature of a laser optics body282of the optical head42. The thermometer274detects a temperature of the cover lens106and the thermometer276detects a temperature of the laser nozzle cooling block248. The optics body282includes an adjustable lens holder spacer284to facilitate the desired focusing of the laser.

The controller80is operably coupled to the thermometers270,272,274,276and may take remedial measures in response to one or more temperatures detected at the thermometers270,272,274,276exceeding a respective threshold. The controller80may have different threshold temperatures set for the different thermometers270,272,274,276. The different threshold temperatures may be due to the upward dissipation of heat from lower components of the optical head42to higher components of the optical head. Further, the temperature thresholds may be set accordingly to the sensitivity of the components of the optical head42. For example, the threshold temperature at thermometer276may be 32° C., the threshold temperature at thermometer274may be 33° C., the threshold temperature at thermometer272may be 35° C., and the threshold temperature at thermometer270may be 40° C. As a further example, the threshold temperatures of the thermometers276,274, and272may all be in the range of approximately 32° C. to approximately 35° C.

Referring toFIG. 10, the hybrid machine tool10includes an automated tool changer300and a magazine302which releasably holds different cutting tools. The automated tool changer300may load and unload tools from the magazine302into the spindle170. As shown inFIGS. 2 and 10, the hot wire welding apparatus40includes an additive manufacturing transformer310for providing electrical power to the components of the hot wire welding apparatus40. The hot wire welding apparatus40further includes a wire heating source controller312, an additive head chilling unit314, a laser resonator316to generate laser light, and a laser resonator chilling unit318for cooling the laser resonator316. The laser resonator316is operatively connected to the optical head42such that the laser light generated by the laser resonator316is routed to the optical head42, and the optical head42focuses the laser light into a beam that is emitted via an aperture tube242(seeFIG. 8). The additive system enclosure14may also include a main spindle chiller320to dissipate heat from the operation of the spindle170.

Referring toFIG. 11, the hybrid machine tool10has an additive process control system350that operates various components of the hybrid machine tool10to facilitate the additive manufacturing process. The additive process control system350utilizes an additive manufacturing hot wire program sequence352which operates an additive manufacturing parameter set macro354. The additive manufacturing hot wire program sequence352communicates via a programmable logic controller356and an application process interface358with power hot wire software360. The power hot wire software communicates via an interface362with the wire heating power source64and the wire feeder52. The wire feeder52may have a master-slave arrangement with the wire feeder54such that the wire feeders52,54coordinate to advance the wire50.

The power hot wire software360may generate a graphical unit user interface364to be provided at a display, such as a screen366(seeFIG. 1) of a user interface368of the hybrid machine tool10. The power hot wire software360may receive the wire speed370and hot wire power372parameters from the additive manufacturing parameter set macro354. The hot wire power372parameter may be, for example, a value or level of power (watts), current (amps), and/or voltage to be applied to the wire.

The power hot wire software360may also receive wire speed374and hot wire power376parameters input via a keyboard369of the user interface368. The user interface368may also include wire speed and hot wire power overrides380to override the current wire speed and a hot wire power. The power hot wire software360also estimates a length377of the wire consumed during an additive process based at least in part on the feed rate and the time elapsed.

The power hot wire software360includes a power source control section384that functions to control supply of a shield gas (e.g., by controlling the solenoid104), operation of the wire heating source64, and operation of the wire feeder52. The wire heating power source64includes a bus master386and a weld controller388whereas the wire feeder52includes a wire drive390and a gas controller392. The gas controller392turns on and off the shield gas provided to the gas circuit99.

The power hot wire software360may receive parameters from the additive manufacturing hot wire program sequence352as well as provide control feedback via the API358. In some applications, the power hot wire software360may also include a dynamic process control system396which operate in conjunction with the additive manufacturing hot wire program sequence352. The dynamic process control system396may provide a closed-loop control system for controlling the machine. The additive process control system350may include software400to facilitate communication between the wire heating power source64, the wire feeder52, and the controller80of the hybrid machine tool10. The communication facilitated by the software400permits the controller80to coordinate operation of the wire heating power source64and wire feeder52with operation of the additive head20.

Continuing reference toFIG. 11, the additive manufacturing hot wire program sequence352may be configured so that a user enters operating parameters into an additive manufacturing parameters set macro354including a laser output parameter410, a shield gas flow parameter412, a wire speed parameter414, and a hot wire power parameter416. Alternatively or additionally, the additive manufacturing hot wire program sequence352may be configured so that the processor82retrieves parameters such as by the processor82retrieving the parameters from a local or remote server via the communication circuitry86and an intranet and/or the internet.

The additive manufacturing hot wire program sequence352next includes the power source control384setting418the shield gas to an “on” state and starting an additive manufacturing macro420. The additive manufacturing macro includes turning on the weld controller388, the optical head42, and the wire drive390. The additive manufacturing macro420further includes receiving a running time parameter422. The running time parameter422represents a dwell time wherein the wire feed is passed to allow the wire to reach the substrate.

The additive manufacturing hot wire program sequence352next includes the additive manufacturing parameter set macro operation424and then stopping426the additive manufacturing macro420. The additive manufacturing parameter set macro operation424takes the programmed additive manufacturing parameters from macro variable data registers and shares them with the power hot wire software360for implementation.

The stopping426may include an identification of a crater time parameter428as well as a burn back time parameter430. The crater time parameter428represents a time period to stop wire feed and build out a crater in the melt pool60. The burn back time parameter430represents a time period to stop wire feed and use the laser to burn back the wire from the substrate and limit adhesion. The stopping426may also include turning off the wire drive390, the weld controller388, and the optical head42. Finally, the additive manufacturing hot wire program sequence352includes turning432the shield gas off.

Referring toFIGS. 12 and 13, the dynamic process control system396may utilize process parameters450and detected parameters452to identify failure modes454and automatically adjust operation of the hybrid machine tool10via one or more corrective actions456. The dynamic process control system396may repeatedly check the process parameters450during a welding process to determine whether one of the failure modes454is occurring. For example, the dynamic process control system396may check the process parameters450at set or varying time periods, e.g. every 10 seconds, or at intervals associated with predetermined movements of the additive head, such as changing a direction of travel or starting/ending a new layer of material. The dynamic process control system396may determine the failure mode454upon a process parameter450approaching a threshold, crossing a threshold, being a percentage of a predetermined value, etc. The determining of the failure mode454may involve determining the failure mode454before the failure mode actually occurs, such as predicting a failure mode based on a trend in one or more of the process parameters450. The one or more corrective actions re-establish a stable welding process as discussed below. The dynamic process control system396may adjust the process parameters450from the start of the welding process to the end at various times through the process and without turning off the laser beam.

The process parameters450may be received from the additive manufacturing hot wire program sequence352and/or received from the user interface368. The process parameters454may include laser output460, shield gas flow462, wire speed464, hot wire power466, additive head position468, and/or table position470. The additive head position468may include an absolute position, speed, velocity, acceleration, direction, and/or a position of the additive head20relative to another component as some examples. The table position470may include absolute position, speed, direction, velocity, acceleration, direction, and/or a position of the table top140as some examples. The process parameters450are provided to the dynamic process control system396initially and then the dynamic process control system396undertakes a feedback loop which may automatically adjust the process parameters450as part of implementing the corrective action456.

The detected parameters452are detected by one or more sensors of the hybrid machine tool10. The detected parameters452may include, for example, the temperature472of the laser system components (such as the temperatures detected by thermometers270,272,274,276), the temperature478of the wire50, the temperature480of the melt pool60, and the temperature482of the substrate. The substrate may be, for example, an initial substrate that the first layer of the bead62is formed on, such as block or plate, or a working substrate in the form of a previously deposited bead62that the wire50is currently being welded to. In one example, the substrate for the first bead is a block to which the wire is welded, the substrate for the second bead is the first bead to which the wire is welded, the substrate for the third bead is the second bead to which the wire is welded, etc.

The detected parameters452also include the Z vertical build height484, and a melt pool appearance parameter486such as the size and/or shape of the melt pool. The detected parameters452may further include one or more light parameters490during deposition, such as the color of the light generated, the intensity of the light generated, interruptions in the light generated, and/or arcing. The change of color may include a change in hue or shade of color. The detected parameters452may further include one or more sound parameters492relating to the sound detected during deposition. The sound parameters492may include a sound amplitude, a sound frequency, and/or different types of sounds, such as crackling, which may indicate deviations from a satisfactory weld.

A stable hot wire welding process may have characteristics relating to the appearance and sound of the welding process that indicate the welding process is stable and will provide a satisfactory weld. In one approach, a stable hot wire welding process may be identified as a process having a consistent orange or yellow glow to the light produced during the welding process. There may be zero or a minor number, such as one or two per minute, of flashes or intense blue light arcs during deposition in any direction of movement of the additive head20. The stable hot wire welding process may also be relatively quiet. There may be no noticeable buzzing, crackling, and/oscillating noise during the deposition. A stable hot wire welding process results in a bead having a clean, bright, and consistent visual appearance. The bead from the weld should have a smooth, bright finish and be of a consistent width and height. The bead should have little or no contamination such as soot or spatter.

Continuing reference toFIG. 13, the dynamic process control system396may utilize the one or more sensors, such as the camera90and/or the microphone92, to monitor the hot wire welding process to determine that excessive arcing500is occurring. Excessive arcing may be detected by bright blue light flashes upon direction changes of the additive head20, bright blue light flashes constantly oscillating along the bead, or bright blue light flashes at random intervals along the bead. The excessive arcing can result in a discontinuous bead, discoloration of the substrate, pitting of the substrate, and/or excessive soot or spatter on the workpiece. The excessive arcing500may be caused by excessive hot wire power466resulting in an arc flash between a discontinuous wire feed and the substrate. The dynamic process control system396may take a corrective action456that includes adjusting502the hot wire power setting. For example, the adjusting502may include adjusting the hot wire power466down in 1% increments until a stable process is detected. The adjusting502may include, for example, adjusting a current, voltage, or a combination of current and voltage to change the electrical power applied to the wire.

The dynamic process control system396may determine that non-linear wire feed of the un-melted wire504is occurring, such as by visually detecting twisting, bending, or other non-linear movement of the wire50via the camera90. Non-linear wire feed is typically caused by the wire not being adequately pre-heated to a plastic state before the wire contacts with the substrate. Due to the wire still being firm, the wire abuts against the substrate and deflects in various directions until the laser energy melts the wire to a liquid state. The remaining, un-melted wire springs back straight and abuts the substrate which restarts the non-linear feed cycle.

The non-linear wire feed wire produces excess stringers attached to finished components. Consistent, noticeable non-linear feed of the wire around the melt pool60causes the wire to be out of position and become welded to the bead62. Less extreme cases of non-linear wire feed can result in pitting around the bead toes and discontinuous beads62. The term bead toes refers to the lateral side portions of the bead where the bead interfaces with the substrate, such as the laterally outermost 7.5%-10% of a cross section of the bead taken perpendicular to the longitudinal length of the bead. The non-linear wire feed of the un-melted wire504may be caused by physical resistance to advancing of the wire50due to contact between improperly heated wire50and the substrate. The corrective action556may include adjusting506the wire speed down in 1% increments until the process stabilizes and non-linear wire feed does not occur.

As an additional or alternative cause, the non-linear wire feed of the unmelted wire504may be caused by inadequate hot wire power466causing an improperly melted wire feed to collide with the substrate. The corrective action556may include adjusting506the hot wire power466up in 1% increments until the process stabilizes and non-linear wire feed does not occur.

The failure modes454may include sagging of additive surfaces508, which may be identified by the camera90. The slumping or sagging of the additive surfaces results in an excessive liquification and a weld bead62that has a lower height and/or is wider than is desired. In one embodiment, the controller80includes a personal computer connected to the hybrid machine tool10via an ethernet connection. The personal computer has software that utilizes data from the camera90and the processor82to compare actual workpiece geometry to projected workpiece geometry. The software of the personal computer determines any deviations, e.g., inadequate bead height, from the projected workpiece geometry and provides a trigger to the processor82of the hybrid machine tool10to address the sagging of additive surfaces508.

In another approach, the processor82may determine the height and/or width of the weld bead62using an image of the weld bead62taken by the camera90, such as a frame of a video, and compare the determined height and/or width of the weld bead62to a target height and/or width.

Further, the slumping or sagging of additive surfaces includes the substrate having an inability to shed heat fast enough and produces a cherry red glow which may be detected via the camera90using thermal imaging. The sagging of additive surfaces508may result in a pool of melted metal and sagging of bead geometry near the center of the bead62. The slumping of additive surfaces508may be caused due to excessive laser power. The corrective action456may include adjusting510the laser output460down in 1% increments until the process stabilizes and sagging of the additive surfaces does not occur.

The failure modes454may also include an inadequate penetration of the bead512. In this failure mode, the bead62(seeFIG. 2) has significant toeing in and excessive bead height relative to the bead width. In one embodiment, the controller80includes a personal computer connected to the hybrid machine tool10via an ethernet connection. The personal computer has software that utilizes data from the camera90and the processor82to compare actual workpiece geometry to projected workpiece geometry. The software of the personal computer determines any deviations from the projected workpiece geometry, e.g., excessive bead height, and provides a trigger to the processor82of the hybrid machine tool10to address the inadequate penetration of the bead512.

In another approach the processor82may determine the toeing in and excessive bead height using an image of the weld bead62taken by the camera90by using an image recognition algorithm that compares the toeing in and bead height of the bead62to target values.

Inadequate penetration of the bead512results in poor bonding between the bead62and the substrate as well as a discontinuous bead. The inadequate penetration of the bead512may be due to inadequate laser power causing lack of penetration of heat into the substrate and an inability to maintain a continuous melt pool60. The corrective action456may include adjusting510the laser output460by increasing the laser power in 1% increments until the process stabilizes and inadequate penetration of the bead512is not occurring.

In some embodiments, the power hot wire software360may be configured to allow a user to manually adjust one or more of the parameters460,462,464,466,468,470during a hot wire welding operation. In this manner, a manual control of the hot wire welding process is available to the user.

RegardingFIG. 14, a method600is provided of utilizing energy from a diffused laser to heat a workpiece. The method600includes measuring602a temperature of a workpiece. The temperature measuring602may include, for example, measuring the temperature of a substrate that has been secured to the table30via the camera90, an infrared thermometer, and/or a thermocouple as some examples.

The method600includes determining604whether the workpiece is at a target temperature. The workpiece target temperature determining604may include, for example, comparing the measured temperature of the workpiece to a baseline value and/or comparing the temperature of the workpiece to a predicted value based on an expected cooling or heating rate for a given time period.

If the workpiece is not at the target temperature, the method600may include adjusting604the additive head20so that the laser emitted from the optical head42is diffused when the laser contacts the workpiece. For example, the adjusting604may include adjusting the position of the additive head20so that the optical head42is sufficiently far away from the workpiece that the laser emitted from the optical head42is diffused when the laser contacts the workpiece. For example, the adjusting604may include positioning the additive head20six to eight inches away from the workpiece. Alternatively or additionally, the adjusting604may include decreasing the power of the laser emitted from the optical head42.

The method600includes heating606the workpiece using the diffused laser. Due to the optical head42being positioned to illuminate the workpiece with a diffused laser, the diffused laser heats the workpiece rather than melting the workpiece. For example, more light from the optical head42is redirected off of the substrate than when the optical head42is positioned to melt the substrate such that the energy of the light is insufficient to melt the substrate.

The method600includes measuring602the temperature of the workpiece and repeating the process until the workpiece is at the desired temperature604. The processor82may continue to monitor the temperature of the workpiece and initiate the method600in response to the temperature of the workpiece deviating from the target temperature.

The method600permits heat treating of a workpiece using the diffused laser rather than having to have a separate oven to heat the workpiece. The heat treating may include, for example, annealing of a workpiece. Further, the method600allows the hybrid machine tool10to raise the temperature of a workpiece to a temperature that may be desirable for hot wire welding simply by using the diffused laser rather than requiring an operator to separately heat the substrate in an oven.

Referring toFIG. 15, a hybrid machine tool700is provided that is similar in many respects to the hybrid machine tool10discussed above. For example, the hybrid machine tool700has a hot wire welding apparatus701similar to the hot wire welding apparatus40discussed above, a cover lens assist gas circuit similar to the cover lens assist gas circuit99discussed above, and a frame assembly with drives that include ball screws, servomotors, and encoders. Further, the hybrid machine tool700is operable to perform the method600discussed above. Another similarity is that the hybrid machine tool700includes an optical head736. In one embodiment, the optical head736has temperature sensors that detect temperatures at different portions of the optical head736and a controller of the hybrid machine tool700compares the detected temperatures against different thresholds for the different portions of the optical head736to determine whether the optical head736is overheating. Any further discussion of similar structures and operations of the hybrid machine tools10,700will be limited for brevity purposes.

The machine tool700includes a controller702that is capable of performing operations similar to those discussed above with respect to the hybrid machine tool10. The hybrid machine tool700includes a housing704enclosing a work room706with a partition720, a base708supporting the housing704, and a lower frame710that may be connected to a conveyance (e.g., a vehicle) for movement of the hybrid machine tool700. The hybrid machine tool700includes an additive head712, a spindle head714, and a table716. The hybrid machine tool700has a partition720that separates the work room706from components of the hybrid machine tool700. The hybrid machine tool700further includes an additive system enclosure722that houses components used for operation of the additive head712.

Referring toFIGS. 16 and 17, the hybrid machine tool700has a frame assembly730including a vertical spindle column732including the spindle head714and a vertical additive head column734including the additive head712. The additive head712includes an optical head736and an arm738that permits shifting of the optical head736in opposite directions along a horizontal Y2-axis739. The optical head736is movable along the Y2-axis739independent of the spindle head714, unlike the spindle head18and additive head20of the hybrid machine tool10which travel together along the horizontal Y-axis126(seeFIG. 3).

The frame assembly730includes an intermediate frame, such as a saddle750, and a base frame752. The saddle750and base frame752have one or more slide connections, such as linear guides754, that permit movement of the saddle750along a horizontal X-axis760orthogonal to the Y2-axis739. The spindle column732and saddle750include one or more slide connections, such as linear guides762, that permit movement of the spindle column732along a horizontal Y1-axis764parallel to the Y2 axis739and orthogonal to the X-axis764. The spindle head714includes one or more slide connections with the spindle column732such as linear guides766that permit shifting of the spindle head714along a vertical Z1-axis768orthogonal to the Y1-axis764, the Y2-axis739, and the X-axis764. As can be seen inFIG. 18, the additive head712and additive head column734include one or more slide connections, such as linear guides770, that permit the additive head712to shift along a vertical Z2-axis772that is parallel to the vertical Z1-axis768and orthogonal to the Y1-axis764, the Y2-axis739, and the X-axis764.

Returning toFIG. 17, the table716includes a table drive780operable to turn a table top782of the table716about a B-axis784and turn the table top782about a C-axis786extending perpendicular to the B-axis784. The table drive780includes one or more motors. The frame assembly730further includes a fixed platform790upon which a workpiece may be supported.

Continuing reference toFIGS. 16 and 18, the partition720includes an opening800and the additive head712includes a flange802that fits in the opening800and a cover804which closes an opening806of an additive head housing808around which the flange802extends. The cover804and housing808cooperate to form an optical head compartment803for protecting the optical head736when not in use. The flange802fills in any gaps between the compartment and the partition720. The additive head712includes a drive810operable to move telescoping portions741A,741B of the arm738from a retracted to an extended position which shifts the cover804and the optical head736(see alsoFIG. 20) outward from the flange802in direction807to position the optical head736in an operative position in the work room706relative to the table716, partition720, and/or fixed support790. In one embodiment, the drive810includes a servomotor, ball screw, and encoder. The servomotor turns the ball screw to extend or retract the telescoping portions741A,741B and linear bearings guide the telescoping portions741A,741B.

As can be seen inFIG. 17, the frame assembly730includes a saddle drive830configured to shift the saddle750along the X-axis760. The spindle column732includes a spindle column drive832operable to shift the spindle column732along the Y1-axis764. The spindle head714further includes a spindle head frame833and a motor852operable to rotate a spindle854of the spindle head714, the motor852being mounted to the spindle head frame833. The spindle head714also has a spindle head drive834operable to shift the spindle head frame833and motor852along the Z1-axis768. With reference toFIG. 18, the additive head drive810may also be configured to shift the additive head712along the Z2-axis772. In one embodiment, the additive head drive810includes a first motor to drive the arm portions741A,741B between the retracted and extended positions and a second motor to drive the housing808supporting the optical head736along the Z2-axis772.

Referring toFIG. 19, the optical head736of the additive head712is configured to direct a laser along an axis850and the spindle head714includes the motor852operable to rotate the spindle854of the spindle head714about an axis856. The axes850,856are separated by a lateral offset858.

RegardingFIG. 20, the additive housing808is shown with the arm portions741A,74B in a retracted position and the optical head736in a stored position relative to the table716, partition720, and/or fixed support790. With the arm portions741A,741B in the retracted position, the arm sections741A,741B are side-by-side and disposed at least partially in the housing808. The housing808further includes one or more walls870and an internal frame872providing rigidity to the housing808.

Referring toFIG. 21, the optical head736includes a wire feeder902for receiving heated wire and directing the wire into a melt pool. The optical head736has a beam input904, a collimator908, and a focus lens910. The optical head736has a triple splitting mirror912configured to split the laser beam into three branches916A,916B,916C and flat adjustable steering mirrors914. The three beam branches916A,916B,916C converge at a point920where the beam branches916A,916B,916C surround the wire and converge directly beneath the wire as the wire enters the melt pool.

The steering mirrors914may be adjusted to change the X, Y location for each beam branch and facilitate high-quality weld while the optical head736is moving in any direction along the substrate. More specifically, the stability of the additive process is generally dictated by how close to optimal conditions the wire can be pre-heated via current from the power source in relation to how well the substrate can be pre-heated via the laser to form the melt pool. Optimal pre-heat of the wire can be described as supplying current to the wire to reach the nearest point of arcing as possible, without causing the wire to actually spatter or arc. Splitting the laser beam into three branches916A,916B,916C so that the laser beam is able to enter the melt pool without affecting the pre-heat of the wire allows for superior control of the additive process parameters, regardless of direction of travel of the additive head. In one embodiment, the optical head736has a power rating of 8 kW.

The optical head736has a focus lens drawer922configured to facilitate balancing of laser power in each of the three beam branches. To monitor the hot wire welding process, the optical head736includes a camera924. The optical head736further includes a nozzle926with a shield gas outlet for directing shield gas toward the weld area. The nozzle926is integrated in a nosecone928of the optical head736.

Uses of singular terms such as “a,” “an,” are intended to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms. It is intended that the phrase “at least one of” as used herein be interpreted in the disjunctive sense. For example, the phrase “at least one of A and B” is intended to encompass A, B, or both A and B.

While there have been illustrated and described particular embodiments of the present invention, it will be appreciated that numerous changes and modifications will occur to those skilled in the art, and it is intended for the present invention to cover all those changes and modifications which fall within the scope of the appended claims. For example, the hybrid machine tools10,700may be operated in a cold wire process, wherein the hybrid machine tools10,70do not heat the wire before welding the wire.