Additive manufacturing process and device by deposition of molten metal wire under concentrated energy with control of the metal wire feed speed

Abstract

A concentrated energy fused wire deposition additive manufacturing process in which a distal end (13A) of the wire (13) is melted with the concentrated energy source (12B) to create a fused end (FE) for depositing the fused metal material from the fused end (FE) onto a support (S); the position of an impact point (PI) of the fused end (FE) on the support (S) is detected; the distance D between the position of the impact point (PI) and the position of the predetermined nominal melting point (PF) is determined; and the feed rate Vf is adjusted according to the distance D. Figure for the abstract: Fig. 3.

Description

Title of the invention: Method and device for additive manufacturing by deposition of molten metal wire under concentrated energy with control of the wire feed speed. Technical field

[0001] The present disclosure relates to an additive manufacturing process by deposition of molten metal wire under concentrated energy with control of the metal wire feed speed, as well as an additive manufacturing device by deposition of molten metal wire under concentrated energy with control of the metal wire feed speed. Previous technique

[0002] During the manufacturing of a part by additive manufacturing using fused deposition modeling (FDM) under concentrated energy, ensuring the geometric integrity of the final part with respect to the desired theoretical shape is particularly challenging, especially for parts with a significant height (e.g., 10 layers or more). Indeed, geometric irregularities form and become more pronounced as the layers are stacked, which, after a certain point, significantly degrades the deposition quality of subsequent layers.

[0003] One solution to overcome this problem is to use cross-passes to form the different layers (i.e., cross-orientations of deposition movements to form successive layers of material), which can help to smooth out irregularities between two successive layers. Another solution consists of dynamically calculating the vertical spacing between the different successive layers, generally by reducing the spacing as the height of the part increases, in order to gain precision during deposition.

[0004] However, these solutions are often complex to implement, can be highly dependent on the geometry of the parts and the material used (copper, nickel, iron, titanium, etc.), take a long time to develop and execute, may depend on the machines on which they are implemented (particularly with regard to tolerances, speeds, accelerations, the type of machine, for example, Cartesian or polar robot, etc.), often require a high level of expertise from the operator to implement them, and ultimately do not always provide complete satisfaction. There is therefore a need for such solutions. Description of the invention

[0005] One embodiment relates to an additive manufacturing process by deposition of molten metal wire under concentrated energy in which a device is provided of additive manufacturing by deposition of molten metal wire under concentrated energy comprising a metal wire feeding system configured to bring the metal wire at a feeding speed Vf and having a feeding nozzle and a concentrated energy source configured to melt a distal end of the metal wire from the feeding nozzle to a predetermined nominal melting point and create a molten end; a distal end of the metal wire is melted with the concentrated energy source in order to create a molten end to deposit the molten metal material from the molten end onto a support; the position of an impact point of the molten end on the support is detected; the distance D between the position of the impact point and the position of the predetermined nominal melting point is determined; and the feeding speed Vf is adjusted according to the distance D.

[0006] For the purposes of this description, "additive manufacturing by deposition of molten metal wire under concentrated energy" means additive manufacturing where the raw material is in wire form, made of metallic material, for example 100% metallic, and is melted by the application of concentrated energy such as a laser, an electron beam, or an electric / plasma arc, etc. Such additive manufacturing may be known to those skilled in the art by the English term "DED metallic wire" for "Direct Energy Deposition metallic wire." For example, laser-wire additive manufacturing, or WLAM for "Wire Laser Additive Manufacturing," is an example of additive manufacturing by deposition of molten metal wire using a laser as a concentrated energy source.As another example, wire arc additive manufacturing, or WAAM, is an example of additive manufacturing by depositing molten metal wire using an electric arc or plasma arc as a concentrated energy source. As yet another example, electron beam additive manufacturing, or EBAM, is an example of additive manufacturing by depositing molten metal wire using an electron beam as a concentrated energy source.

[0007] The metal wire may have any cross-sectional shape and / or dimensions, and may comprise any type of metal or metal alloy, at any degree of purity, for example, copper, nickel, aluminum, iron, titanium, etc., or any alloy based on such metals or other metals. For example, the metal wire may be a wire with a solid and continuous cross-section, or a cored wire (i.e., a wire comprising a continuous metal sheath and a core comprising a metal powder). For example, the metal wire may be 100% metal by mass. Hereafter, and unless otherwise specified, "wire" means "metal wire."

[0008] The feeding system supplies the feed nozzle with wire and distributes or delivers the wire at the nozzle outlet at a feed rate Vf. The feed system is configured to allow for variable feed rate (Vf). The concentrated energy source is configured to melt the wire, or a distal or free end of the wire (or a portion of the distal end), downstream of the feed nozzle outlet. By continuously delivering wire, the concentrated energy source allows for continuous melting of the wire and continuous deposition of molten metal material onto the substrate. In the following, unless otherwise specified, "nozzle" refers to the "feed nozzle."

[0009] The predetermined nominal melting point is the point (or location, or geometric point) where the energy concentration of the concentrated energy source is such that the metal wire melts. This point is nominal, meaning that it corresponds to the point where, by design, manufacture, and / or development, the concentrated energy source, under normal operating conditions, melts the metal wire. This point is predetermined, meaning that it does not vary and remains in the same position under normal operating conditions. For example, the predetermined nominal melting point may be located a few millimeters downstream of the nozzle outlet in the direction of wire advance from the nozzle outlet, for example, directly above the nozzle (i.e., on a line perpendicular to the plane of the nozzle outlet and centered on the nozzle outlet).In the example of a laser as a concentrated energy source, the predetermined nominal melting point does not necessarily correspond to the laser's focal point, as such a focal point could lead to an excessively high and undesirable energy concentration. In this case, the focal point could, for example, be located beyond the support. Hereafter, and unless otherwise specified, "nominal point" refers to the "predetermined nominal melting point."

[0010] For the purposes of this description, the term "support" generally refers to the surface onto which the molten metallic material from the molten end of the wire is deposited. Thus, the support can be either the support itself, on which the part being manufactured is formed, or the previous metal deposition layer on which a new layer is being formed / deposited.

[0011] The point of impact is an abstract theoretical point representing the contact area or surface between the support (or the preceding layer) and the melted end of the wire. For example, the point of impact may be the geometric center, or the centroid, of the contact area between the surface and the melted end of the wire.

[0012] The detection of the impact point can be carried out by any means known to a person skilled in the art, for example by optical sensor and possible post-processing of the captured image, a laser sensor, a probe, etc. For example, the laser sensor or the probe can point on the surface of the support at a point immediately adjacent, for example a few tenths of a millimeter or a few millimeters away, to the point of impact (i.e., at a point immediately adjacent to a projection of the geometric center of the nozzle outlet, directly above the nozzle outlet). nozzle ie in a plane perpendicular and in the immediate vicinity, for example a few millimeters or tenths of millimeters, of a line perpendicular to the plane of the nozzle outlet and centered on the nozzle outlet), such a measurement point, forming a measured impact point, can be representative of the position of the impact point in a sufficiently reliable manner.

[0013] The distance D can be determined by any means known to a person skilled in the art. For example, the distance D can be determined via post-processing and / or calculation involving data relating to the positions of the melting point and the impact point, the position of the melting point being known in advance.

[0014] For example, with respect to the direction of filament feed from the nozzle, if the impact point is upstream of the melting point, the distance D can be negative, while if the impact point is downstream of the melting point, the distance D can be positive. For example, when the distance D is negative, the feed rate Vf can be adjusted to reduce it, and conversely, when the rate D is positive, the feed rate Vf can be adjusted to increase it. The reduction or increase in the feed rate Vf can be proportional to the sign of the distance D and / or to the absolute value (or magnitude) of the distance D. For example, when the distance D is zero (D=0), the feed rate Vf can be equal to a nominal feed rate VfO. For example, when the distance D does not change, the feed rate Vf also does not change.For example, the supply speed Vf varies only as a function of the distance D (i.e., no other parameter influences the supply speed Vf).

[0015] The distance D can be representative of the surface irregularities of the substrate. Thus, by adjusting the wire feed rate according to this distance D, the wire flow rate can be increased and more material delivered where the distance is large, i.e., where there are "hollows," and the wire flow rate can be reduced and less material delivered where the distance D is small, i.e., where there are "bumps." This can make it possible to form a layer with a particularly regular apparent surface, thus ensuring high geometric conformity of the final part, regardless of the flatness of the substrate surface.

[0016] Adjusting the filament feed rate as a function of the distance D can allow for dynamic regulation of the filament flow rate based on the material being applied to the substrate at any given moment. For example, assuming a perfectly flat substrate, if the relative speed between the nozzle and the substrate decreases or even becomes zero, excessive material may be applied if the filament feed rate Vf remains unchanged. This can occur, in particular, during changes in the nozzle's direction relative to the substrate, for example, to form an angle or to perform a back-and-forth movement. Conversely, always Assuming a perfectly flat substrate, if the relative speed between the nozzle and the substrate increases, insufficient material may be delivered if the filament feed rate (Vf) remains unchanged. This can occur, in particular, after a change in nozzle direction, when the nozzle's movement relative to the substrate reaches its nominal speed. Regulating the filament feed rate (Vf) based on the distance (D) can ensure the precise amount of material required to form the layer, resulting in a layer with a particularly smooth surface finish and thus guaranteeing high geometric conformity of the final part, regardless of the relative speed between the nozzle and the substrate.

[0017] Such regulation is relatively simple to implement, and the parameters involved are independent of the implementation context (geometry, materials, orientation of relative movements during nozzle passes on the support, type of machine, operator experience, etc.). The process is therefore particularly robust and economical in terms of time and money, and can eliminate all or part of the development operations required in prior art processes, while still allowing the production of a final part with high geometric conformity to the desired theoretical shape.

[0018] In some embodiments, the feed rate Vf can be adjusted by applying a correction Vc dependent on the distance D according to a function Vc = f(D).

[0019] For example, the velocity Vf at a time t can be equal to the velocity Vf at a time t-1 corrected by the correction Vc calculated from the distance D determined at time t-1. In other words, the feed rate Vf can be corrected according to the formula Vf(t) = Vf(tl) + Vc(tl) (or Vf(t) = Vf(tl) + Vc(D(tl)). For example, when the distance D is zero, the correction Vc can be zero (i.e., the rate Vf remains unchanged and equal to the nominal rate VfO); when the distance D is positive, the correction Vc can be positive (i.e., the rate Vf is increased relative to the nominal rate VfO); and when the distance D is negative, the correction Vc can be negative (i.e., the rate Vf is decreased relative to the nominal rate VfO). The function Vc = f(D) or Vc(t) = f(D(t)) can be any function, or correction law.

[0020] Such a correction can be relatively simple to implement while still allowing for satisfactory adjustment of the feed rate Vf. In particular, the calculation times associated with such a correction can be particularly short, enabling particularly fine and responsive control, which can contribute to improving the geometric conformity of the final part obtained.

[0021] In some embodiments, the function f(D) can be bounded.

[0022] As a reminder, a bounded function is a function whose set of values ​​lies between a minimum value and a maximum value. In other words, the set of values ​​taken by the function f(D) lies between a minimum value Vcmin and a maximum value Vcmax, regardless of D. In absolute value, Vcmin can be equal to Vcmax, but not necessarily so. Vcmin can be a negative value while Vcmax can be a positive value.

[0023] Thus, the speed Vf can be reduced by a maximum value of Vcmin and increased by a maximum value of Vcmax. This can ensure a certain regularity in the wire feed, thereby preventing a interruption in the wire feed that could result in a discontinuity in the molten metal deposition or, conversely, an excessively rapid wire feed that could lead to incomplete or poor-quality wire melting and / or material buildup or jamming (a phenomenon also known to those skilled in the art as "excess material"). Both of these consequences can be detrimental to the geometric integrity of the final part, and in some extreme cases, even cause material damage, particularly to the feeding system (nozzle and / or concentrated energy source).Such a bounded function can therefore, in particular, contribute to improving the geometric conformity of the final part obtained.

[0024] In some embodiments, the concentrated energy source can be controlled as a function of the temperature of the melted end.

[0025] For example, the intensity or power of the concentrated energy source is controlled. For example, the temperature considered for regulating the energy source can be the temperature of the melted end at the point of impact. The temperature of the melted end can, for example, be determined using a temperature sensor or a thermal imaging camera. For example, the temperature of the melted end at the point of impact can vary as a function of the distance D, but also as a function of other parameters such as the effective temperature of the substrate, which can vary depending on the number of passes already performed.Such regulation can ensure better deposition quality, specifically preventing the deposited molten metal from being at too low a temperature to guarantee good deposition quality, or too high a temperature to ensure the deposited metal retains a certain mechanical strength, guaranteeing geometric stability until solidification. Combining this energy source regulation with feed rate regulation can create a synergy leading to high process stability, high metal deposition quality, and ultimately, high geometric conformity of the final part.

[0026] An embodiment relates to a computer program comprising instructions which, when the program is executed by a computer, lead the computer to implement the additive manufacturing process by deposition of molten metal wire under concentrated energy according to any of the embodiments described in this exposition.

[0027] This program may use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0028] An embodiment relates to a computer-readable data carrier on which the computer program is recorded according to any one of the embodiments described in this exposition.

[0029] The recording medium can be any entity or device capable of storing a program. For example, the medium can include a storage means, such as a ROM, for example a CD-ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a floppy disk or a hard disk drive. Alternatively, the recording medium can be an integrated circuit or a dedicated electronic board in which the program is incorporated, the circuit or board being adapted to execute or to be used in the execution of the process in question.

[0030] One embodiment relates to an additive manufacturing device for molten metal wire deposition under concentrated energy comprising, a metal wire feeding system configured to bring the metal wire to a feeding speed Vf, and having a feeding nozzle and a concentrated energy source configured to melt a distal end of the metal wire from the feeding nozzle to a predetermined nominal melting point and create a molten end, a detection system configured to detect the position of an impact point of the molten end on a support, a computer configured to determine the distance D between the position of the impact point and the position of the predetermined nominal melting point, and a control unit configured to adjust the feeding speed Vf as a function of the distance D.

[0031] The detection system may include any means otherwise known to a person skilled in the art, for example, an optical sensor with possible post-processing of the captured image, a laser sensor, a probe, etc. For example, the laser sensor or the probe may point on the surface of the support at a point immediately adjacent, for example, a few tenths of a millimeter or a few millimeters away, from the point of impact (i.e., at a point immediately adjacent to a projection of the geometric center of the nozzle outlet, directly above the nozzle outlet, i.e., in a plane). perpendicular and in the immediate vicinity, for example a few millimeters or tenths of millimeters, of a line perpendicular to the plane of the nozzle outlet and centered on the nozzle outlet), such a measurement point, forming a measured impact point, can be representative of the position of the impact point in a sufficiently reliable manner.

[0032] The calculator may include, for example, any means otherwise known to a person skilled in the art. For example, the distance D may be determined via post-processing and / or calculation involving data relating to the positions of the melting point and the impact point, the position of the melting point being known in advance.

[0033] Such a device can be relatively simple to implement, and the parameters involved are independent of the implementation context (geometry, materials, orientation of relative movements during nozzle passes on the support, type of machine, operator experience, etc.). Such a device is therefore particularly robust and economical in terms of time and money, and can eliminate all or part of the adjustment operations required on prior art devices, while still allowing the production of a final part with high geometric conformity to the desired theoretical shape.

[0034] In some embodiments, the control unit can be configured to adjust the feed rate Vf by applying a correction Vc dependent on the distance D according to a function Vc =f(D).

[0035] For example, the velocity Vf at a time t can be equal to the velocity Vf at a time t-1 corrected by the correction Vc calculated from the distance D determined at time t-1. In other words, the feed rate Vf can be corrected according to the formula Vf(t) = Vf(tl) + Vc(tl) (or Vf(t) = Vf(tl) + Vc(D(tl)). For example, when the distance D is zero, the correction Vc can be zero (i.e., the rate Vf remains unchanged and equal to the nominal rate VfO); when the distance D is positive, the correction Vc can be positive (i.e., the rate Vf is increased relative to the nominal rate VfO); and when the distance D is negative, the correction Vc can be negative (i.e., the rate Vf is decreased relative to the nominal rate VfO). The function Vc = f(D) or Vc(t) = f(D(t)) can be any function, or correction law.Such a correction can be relatively simple to implement while still allowing for satisfactory adjustment of the feed rate Vf. In particular, the calculation times associated with such a correction can be particularly short, enabling particularly fine and responsive control, which can contribute to improving the geometric conformity of the final part obtained.

[0036] In some embodiments, the function f(D) can be bounded.

[0037] Such a correction can be relatively simple to implement while allowing a satisfactory adjustment of the supply speed Vf. In particular, the Calculation times associated with such a correction can be particularly short, allowing for particularly fine and responsive regulation, which can contribute to improving the geometric conformity of the final part obtained.

[0038] In some embodiments, the control unit can be configured to control the concentrated energy source according to the temperature of the melted end.

[0039] For example, the control unit can control the intensity or power of the concentrated energy source. For example, the temperature considered for regulating the energy source can be the temperature of the melted end at the point of impact. The temperature of the melted end can, for example, be determined using a temperature sensor or a thermal imaging camera. For example, the temperature of the melted end at the point of impact can vary as a function of the distance D, but also as a function of other parameters such as the effective temperature of the substrate, which can vary depending on the number of passes already performed.Such regulation can ensure better deposition quality, specifically preventing the deposited molten metal from being at too low a temperature to guarantee good deposition quality, or too high a temperature to ensure the deposited metal retains a certain mechanical strength, guaranteeing geometric stability until solidification. Combining this energy source regulation with feed rate regulation can create a synergy leading to high process stability, high metal deposition quality, and ultimately, high geometric conformity of the final part. Brief description of the drawings

[0040] The purpose of this presentation and its advantages will be better understood upon reading the detailed description below of various embodiments given by way of non-limiting examples. This description refers to the accompanying figure pages, on which:

[0041] [Fig-1] Fig. 1 schematically represents an additive manufacturing device by deposition of molten metal wire under concentrated energy,

[0042] [Fig.2] Fig.2 represents a flowchart of an additive manufacturing process by deposition of molten metal wire under concentrated energy,

[0043] [Fig.3] Fig.3 schematically represents the head of the additive manufacturing device of Fig.1, in operation, and

[0044] [Fig. 4] [Fig. 4] shows a comparative tomographic cross-section between a part manufactured according to a prior art process and device and a part manufactured according to a process and device according to the present disclosure. Description of embodiments

[0045] Figure 1 schematically represents an additive manufacturing device for fused metal wire deposition under concentrated energy 10, comprising a wire feeding system 12 configured to deliver the wire 13 at a feed rate Vf and having a feed nozzle 12A and a concentrated energy source 12B configured to melt a distal end 13A of the wire 13 from the feed nozzle 12A to a predetermined nominal melting point PF and create a fused end EF (see Figure 3), a detection system 14 configured to detect the position of an impact point PI (see Figure 3) of the fused end EF on a support S, a computer 16A configured to determine the distance D (see Figure 3) between the position of the impact point PI and the position of the predetermined nominal melting point PF, and a control unit 16B configured to adjust the feed rate Vf depending on the distance D.In this example, the 16B control unit is configured to adjust the feed rate Vf by applying a distance-dependent correction Vc D according to a function Vc = f(D). In this example, the function f(D) is bounded.

[0046] The wire feed system 12 with wire 13 may include a wire spool 15 driven in rotation by a servo motor (not shown), thereby allowing the speed Vf to be adjusted. In this example, the concentrated energy source 12B is a laser, but any other concentrated energy source is possible. The laser 12B may be powered by a laser generator 12C, which may be servo-controlled. In this example, the laser 12B is a coaxial laser with the nozzle 12A and the wire feed 13, but any other configuration is possible, for example, a laser with lateral wire feed.

[0047] In this example, the detection system 14 may include a laser sensor configured to point on the surface of the support S at a point immediately adjacent to, for example, a few tenths of a millimeter or a few millimeters away from the impact point PI (i.e., at a point immediately adjacent to the geometric center of the feed nozzle outlet, directly above the feed nozzle outlet). In this example, the laser sensor 14 may be configured to point upstream of the impact point PI in the direction of travel F of the nozzle 12A, the nozzle 12A moving from upstream AM to downstream AV.The detection system 14 may include several laser sensors, only one sensor being shown in the figures for clarity of explanation, these sensors being regularly distributed around the nozzle 12A to ensure that there is always a laser sensor pointing downstream of the point of impact PI, particularly in the event of a change in direction F of advancement of the nozzle 12A by the arm 18.

[0048] The feeding system 12 and the detection system 14 can be mounted on an arm 18 configured to move the feeding system 12 and the detection system 14 relative to a platform 20, for example in a lengthwise direction X, a width direction Y, and a height direction Z. The arm 18 can be of any type, for example, a Cartesian robot arm or a polar robot arm. The platform 20 is configured to receive and hold a support S. The feeding system 12 and the detection system 14 can together form a head 15 of the additive manufacturing device 10, this head 15 being mounted on one end of the arm 18 and moved by the arm 18. To make a layer, the arm 18 moves the head 15 in the X and / or Y direction, and to make a subsequent layer, the arm moves the head in the Z direction, upwards on the [Fig. 1], and then again in the X and / or Y direction.

[0049] The computer 16A and the control unit 16B can be combined into an electronic control unit 16 (or ECU for Electric Control Unit). For example, the calculator 16A and the control unit 16B can be formed by a single microprocessor.The electronic control unit 16 may include a ROM 16C, forming an example of a computer-readable data carrier, on which is stored the computer program comprising instructions which, when executed by a computer, cause the computer to implement the additive manufacturing process by deposition of fused metal wire under concentrated energy described below. In [Fig. 1], the arrows on the connections (wired or wireless) between the electronic control unit 16 and the various elements of the device 10 symbolize the direction of the information flow. In particular, the computer 16A receives information from the detection system 14, while the control unit 16B sends information to the power supply system 12, in this example to the servo motor (not shown) configured to unwind the spool 15 of wire 13.

[0050] In this example, the control unit 16B is configured to control the concentrated energy source 12B based on the temperature of the molten end EF. In this example, the additive manufacturing device 10 may include a thermal camera 22 configured to measure the temperature of the molten end EF. The data collected by the thermal camera 22 can be transmitted to the computer 16A for post-processing. The control unit 16B, based on the data processing performed by the computer 16A, can control and transmit information to the laser generator 12C in order to adjust the intensity or power of the concentrated energy source 12A.

[0051] An example of the implementation of the manufacturing device 10 will now be described with reference to Figures 2 and 3. Figure 2 is a flowchart representing different stages of an additive manufacturing process by deposition of molten metal wire under concentrated energy PRO, while Figure 3 represents the progression of the deposition of a metallic layer at different locations on a support S. The left part of Figure 3 represents a first configuration of the support S and a phase associated deposition while the right part of [Fig.3] represents a second configuration of the support S, in this example downstream of the first configuration of the support S of the left part of [Fig.3], according to the direction of movement F of the head 15 (from left to right on [Fig.3]), and an associated deposition phase following the deposition phase of the left part of [Fig.3].

[0052] In the context of the concentrated energy fused wire deposition additive manufacturing process PRO, a concentrated energy fused wire deposition additive manufacturing device is first provided comprising a wire feeding system 12 configured to bring the wire 13 to a feeding speed Vf, and having a feed nozzle 12A and a concentrated energy source 12B configured to melt a distal end 13A of the wire 13 from the feed nozzle 12A to a predetermined nominal melting point PF and create a fused end EF, such as the device 10 described above with reference to [Fig. 1].

[0053] During a step E1, a distal end 13A of the metal wire 13 is melted with the concentrated energy source 12 to create a molten end EF. The molten metal material from the molten end EF is then deposited onto the support S. In [Fig. 3], the support S is positioned on the platform 20. The head 15 of the device 10 moves along the arrow F relative to the support S, forming a bead 50 of metal deposition. The dashed lines from the concentrated energy source 12B represent the concentration of the laser beam towards the melting point PF.

[0054] During a step E2, the position of an impact point PI of the fused end EF on the support S is detected. In this example, to detect the position of the impact point PI, the detection system 14 detects the position of a measured impact point PIM, which is representative of the position of the impact point PI. The dashed line from the detection device 14 symbolizes the laser beam for measuring the position of the point PIM.

[0055] Next, in a step E3, the distance D between the position of the impact point PI and the position of the predetermined nominal melting point PF is determined. In this example, the detection system 14 measures a relative distance along the Z direction between itself and the measured impact point PIM. Since the position of the melting point PF is known from the outside, post-processing of the data from the detection system 14 by the computer 16A allows the distance D to be calculated. On the left side of [Fig. 3], the impact point PI coincides with the melting point PF, so the distance D is zero (D=0). On the right side of [Fig. 3], the impact point PI is "below" the melting point PF along the height direction Z, so the distance D is non-zero and positive.

[0056] Next, during a step E4, the feed rate Vf is adjusted according to the distance D. For example, in the left-hand side of [Fig. 3], the distance D is zero and the adjustment or correction of the feed rate Vf is zero, so the rate Vf can be equal to a nominal feed rate VfO. This rate VfO corresponds, for example, to a nominal configuration where the impact point PI and the melting point PF coincide. In the example in the right-hand side of [Fig. 3], the distance D is non-zero and positive, and the adjustment or correction of the feed rate Vf is positive, so the rate Vf is increased compared to the configuration in the left-hand side of [Fig. 3].

[0057] It should be noted that such an adjustment makes it possible, in particular, to compensate for surface irregularities on the support S. On the left side of [Fig. 3], the impact point PI is located at a nominal position, so that the feed speed of the wire 13 is also at a nominal speed VfO, and the deposited metal bead 50 has a thickness EPI along the height direction Z corresponding to a nominal height. On the right side of [Fig. 3], the support S has a depression or hollow, relative to the right side, so that the speed Vf on this part is greater than the speed VfO. This makes it possible to obtain a greater material supply to fill this depression, the deposited metal bead 50 having a thickness EP2 greater than the thickness EPI, but ultimately resulting in a generally flat layer surface 50.Conversely, if the support S had a protruding surface, the feed velocity Vf would be reduced compared to the VfO velocity, allowing less material to be deposited to compensate for this protrusion and ultimately obtain a generally flat layer surface. Such a dynamic adjustment of the feed velocity Vf also compensates for any deposition irregularity resulting from the deceleration / acceleration of arm 18 during changes of direction, as point PI tends to "rise" along the Z-axis when arm 18 decelerates and to "fall" along the Z-axis when arm 18 accelerates. In this example, if the distance D does not change, the velocity Vf does not change.

[0058] In this example, the feed rate Vf is adjusted by applying a correction Vc that depends on the distance D according to a function Vc = f(D). In this example, the function f(D) is bounded. In this example, the rate Vf at time t is equal to the rate Vf at time t-1 corrected by the correction Vc calculated from the distance D determined at time t-1. In other words, the feed rate Vf is corrected according to the formula Vf(t) = Vf(tl) + Vc(D(tl)). In this example, steps E2 and E3 can be implemented in a loop to determine the distance D at each time t, so that the rate adjustment Vf can be updated at the next machine time t+1. In this example, if the distance D does not change, the correction Vc does not change.

[0059] In this example, the PRO process includes an optional step E5 in which the concentrated energy source 12B is controlled according to the temperature of the molten end EF. For example, the thermal camera 22, not shown in [Fig. 3], films the molten end EF continuously and sends the captured data to the computer 16A for post-processing, while the control unit 16B, based on the result of the processing performed by the computer 16A, controls the laser generator 12C to adjust the intensity or power of the concentrated energy source 12A. In this example, steps E1 and E5 can be implemented in a loop to determine the temperature of the molten end EF at time t and control the concentrated energy source 12B at the following machine time t+1.

[0060] The PRO process and the additive manufacturing device 10 described herein make it possible to obtain parts, particularly tall parts along the Z-height direction, exhibiting a high degree of geometric conformity to the desired theoretical shape. Figure 4 shows a comparative tomographic cross-section of a theoretical reference parallelepiped shape.

[0061] More specifically, [Fig. 4] is a photograph of a comparative tomographic cross-section of two parallelepiped-shaped parts 100A and 100B, derived from the same theoretical reference part (or even the same 3D digital model). The test part 100A was manufactured according to the PRO process in which the speed Vf is adjusted as a function of the distance D, while the control part 100B was manufactured according to a prior art process in which the speed Vf is not controlled as a function of the distance D. The inset in the upper right of [Fig. 4] shows parts 100A and 100B viewed in perspective on the same support plate PS, while the main view of [Fig. 4] shows a cross-sectional view along the cutting plane PC of the inset, of parts 100A and 100B as well as the support S.

[0062] It can be seen that the test piece 100A, obtained according to the PRO process and with the device 10 as described herein, exhibits very high geometric conformity, the vertical walls of the section being very regular and the angles between the different faces of the parallelepiped shape being entirely satisfactory and exhibiting very localized, minimal rounding. The test piece 100A has, relative to the control piece 100B, a very large height Hl, in this example resulting from 20 passes (i.e., 20 layers).

[0063] The test piece 100B, obtained using a process and device according to the prior art, exhibits relatively deformed vertical walls. In particular, it is observed that the last passes resulted in significant defects, notably a sagging of material AF, the metal having melted and flowed from the last layers onto the support S, on the sides. These defects prevented the completion of more than 10 passes (i.e., 10 layers), as the surface condition and the condition of the last layer did not permit further processing. No further passes are required. The control part 100B therefore ultimately has a height H2 less than the height H1 of the test part 100A, the test part 100A having a height H1 equal to twice the height H2.

[0064] This tomographic section also shows that the PRO process and the device 10 according to this presentation preserve the qualities of deposition obtained elsewhere, and in particular make it possible to obtain a part 100A with a homogeneous and satisfactory density.

[0065] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

[0066] It is also evident that all the characteristics described with reference to a process are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a process.

Claims

Demands

1. A method for additive manufacturing by deposition of fused metal wire under concentrated energy (PRO) wherein: - an additive manufacturing device by deposition of fused metal wire under concentrated energy (10) is provided, comprising a metal wire feeding system (12) configured to bring the metal wire (13) to a feeding speed Vf, and having a feeding nozzle (12A) and a concentrated energy source (12B) configured to melt a distal end (13A) of the metal wire (13) from the feeding nozzle (12A) to a predetermined nominal melting point (PF) and create a fused end (EF); - a distal end (13A) of the metal wire (13) is melted with the concentrated energy source (12B) in order to create a fused end (EF) to deposit the molten metal material from the fused end (EF) onto a support (S);- we detect (E2) the position of an impact point (PI) of the molten end (EF) on the support (S); - we determine (E3) the distance D between the position of the impact point (PI) and the position of the predetermined nominal melting point (PF); and - we adjust (E4) the feed rate Vf as a function of the distance D.;

2. A process for additive manufacturing by deposition of fused metal wire under concentrated energy (PRO) according to claim 1, wherein the feed rate Vf is adjusted by applying a correction Vc dependent on the distance D according to a function Vc = f(D).

3. A process for additive manufacturing by deposition of molten metal wire under concentrated energy (PRO) according to claim 2, wherein the function f(D) is bounded.

4. A method of additive manufacturing by deposition of molten metal wire under concentrated energy (PRO) according to any one of claims 1 to 3, wherein the concentrated energy source (12B) is controlled (E5) as a function of the temperature of the molten end (EF).

5. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to implement the additive manufacturing process by deposition of metal wire melted under concentrated energy (PRO) according to any one of claims 1 to 4.

6. Computer-readable data carrier (16C) on which the computer program according to claim 5 is recorded.

7. Concentrated energy fused wire deposition additive manufacturing device (10) comprising, a wire feeding system (12) configured to bring the wire (13) to a feed rate Vf and having a feed nozzle (12A) and a concentrated energy source (12B) configured to melt a distal end (13A) of the wire (13) from the feed nozzle (12A) to a predetermined nominal melting point (PF) and create a fused end (EF), a detection system (14) configured to detect the position of an impact point (PI) of the fused end (EF) on a support (S), a computer (16A) configured to determine the distance D between the position of the impact point (PI) and the position of the predetermined nominal melting point (PF), and a control unit (16B) configured to adjust the feed rate Vf as a function of the distance D.

8. Concentrated energy fused wire deposition additive manufacturing device (10) according to claim 7, wherein the control unit (16B) is configured to adjust the feed speed Vf by applying a distance-dependent correction Vc according to a function Vc =f(D).

9. Device for additive manufacturing by deposition of molten metal wire under concentrated energy (10) according to claim 8, wherein the function f(D) is bounded.

10. Concentrated energy molten wire deposition additive manufacturing device (10) according to any one of claims 7 to 9, wherein the control unit (16B) is configured to control the concentrated energy source (12B) as a function of the temperature of the molten end (FE).

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