Laser metal deposition apparatus and method with wire force detection using multi-axis force sensors

Abstract

The laser metal deposition apparatus (1) comprises a wire nozzle (100) for feeding a wire (101) to be deposited on a substrate (200), a laser source (300) for feeding a laser beam (301) configured to melt the wire, a multi-axis force sensor (120) configured to determine the force between the wire and the substrate, and a controller (130). The controller (130) is adapted (configured) to control at least one of the following based on the force measured by the multi-axis force sensor: the output power of the laser source, the current supplied to the wire, the relative movement speed of the wire nozzle and laser beam with respect to the substrate, or the displacement of the wire and / or wire nozzle with respect to the laser beam in at least one axis.

Description

Technical Field

[0001] The present disclosure relates to a laser metal deposition apparatus. In particular, the present invention relates to a laser metal deposition apparatus having a force feedback control of deposition apparatus output parameters.

Background Art

[0002] Metal additive manufacturing is a technique for depositing metal on the surface of a substrate. One additive manufacturing technique utilizes a laser metal deposition system for wire (LMD-w (Laser Metal Deposition of wire) system), whereby a metal wire, strip or band is melted within a pool of heated material on the substrate, and the material is generally heated via a laser system focused at the interface between the wire tip and the substrate.

[0003] The deposited metal can be used for welding or cladding applications. During the deposition process, the tip of the wire being deposited and the laser beam are generally moved relative to the substrate on which the deposition is being performed. That is, in known laser metal deposition systems, the laser beam and the wire remain in a fixed relationship with each other, and the laser beam and the wire are moved relative to the substrate. The laser source and the wire nozzle are typically rigidly connected to a gantry or robotic arm that can move the laser source and the wire nozzle relative to the substrate. In some devices, the laser source and the wire nozzle can be maintained in a fixed position while the substrate is provided on a movable platform. The platform is typically movable in the XY directions.

[0004] The fixed relationship between the laser beam and the wire nozzle is intended, for example, to minimize inadvertent misalignment.

[0005] Patent Document 1 discloses a control system for maintaining process stability in an additive manufacturing process by determining the conductance between metal strips, i.e., wires, and adjusting process parameters based on the measured conductance.

[0006] However, improved systems are desired. For example, when depositing thin beads of material, precise control of the deposition process is required. Cladding processes may require the deposition of beads less than approximately 2 mm in size onto a metal substrate. At such small dimensions, improvements to the deposition system and a control system for deposition are necessary to provide reliable and efficient deposition.

[0007] Stubbing is a detrimental process mode in laser metal deposition, where the solid wire comes into contact with the solid metal below the metal pool. Stubbing causes wire vibration, leading to fusion defects. Therefore, smooth metal transfer must be maintained throughout the entire deposition sequence to ensure good material quality.

[0008] Apparatus, systems, and methods with improved deposition control and particularly improved recovery from harmful process modes would be advantageous. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] International Publication WO2021 / 110793 (Procada AB) (Corresponding Japanese document: JP 2023-504486) [Overview of the Initiative]

[0010] Therefore, the present invention preferably aims to mitigate, alleviate, or eliminate one or more of the defects and shortcomings of the art identified above, either individually or in any combination, and provides a laser metal deposition apparatus to solve at least the above problems. The laser metal deposition apparatus of the present invention comprises a wire nozzle for feeding a wire to be deposited on a substrate; a laser source for feeding a laser beam configured to melt the wire; a multi-axis force sensor configured to determine the force between the wire and the substrate; and a controller adapted to control at least one of the following based on the force measured by the force sensor: the output power of the laser source, the relative movement speed of the wire nozzle and the laser beam with respect to the substrate, or the displacement of the wire and / or wire nozzle with respect to the laser beam in at least one axis.

[0011] Force feedback control of deposition output parameters such as the output power of the laser source, the relative movement speed of the wire nozzle and laser beam relative to the substrate, or the displacement of the wire and / or wire nozzle relative to the laser beam in at least one axis, results in improved deposition performance and control. The apparatus can deposit relatively thin metal beads with improved performance because variations such as wire curvature and wire quality can be compensated for during deposition. Other means of process monitoring, such as conductance measurement, exhibit relatively low sensitivity to wire-substrate interaction / stub compared to force measurement.

[0012] The wire nozzle for feeding the wire and / or the wire to be deposited on the substrate is advantageously adapted to move relative to the laser beam.

[0013] Multi-axis force sensors are particularly advantageous for detecting harmful process modes. Furthermore, when force feedback control is combined with conductance control, conductance measurements can be used to detect drops, and force sensors can be used to detect harmful process modes at stub or other wire locations. Since the measured force is a vector entity rather than a scalar, it also provides directional information. This offers an opportunity for directional actuation of the control response using multi-axis actuators.

[0014] Furthermore, since the measured force is a force vector and not a scalar, it can be used to detect complex interactions with the substrate, such as stubs in the direction of wire feeding, forces orthogonal to the feeding direction, and lasers that enable multi-axis controlled responses.

[0015] A method for operating a laser metal deposition apparatus is provided. A method for detecting and recovering stubs for laser metal deposition apparatus is also provided.

[0016] Further advantageous embodiments are disclosed in the appended claims and dependent claims.

[0017] These and other possible embodiments, features, and advantages of the present invention will become apparent and will be described from the following description of embodiments of the invention with reference to the accompanying drawings. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic diagram of a laser metal deposition apparatus according to one embodiment. The diagram shows three axes: X (approximate direction of travel), Y (direction within the page), and Z (vertical direction, approximately parallel to the laser beam). The dashed lines show an example of data transmission and reception from a force sensor to an actuator and from the actuator. [Figure 2] This is a flowchart of the deposition process according to one embodiment. [Figure 3]This is a control system diagram showing the control of the wire position relative to the laser beam based on force measurement. [Figure 4] This plot shows the measured Z-height, conductance, and force components in the Z and Y axes for an intentionally unstable process. The plot details the results of Experiment 2. [Modes for carrying out the invention]

[0019] As shown in Figure 1, the laser metal deposition (LMD-w) apparatus 1 comprises a laser source 300 for providing a laser beam 301 and a wire nozzle 100 for supplying a wire 101. The laser beam 301 is directed toward a substrate 200. The wire nozzle 100 supplies the wire 101 toward the substrate 200. The wire 101 is melted in the substrate 200 by at least the laser beam 301. The melting forms a pool of molten material, metal, which can be used to weld or build layers on the substrate 200. The apparatus 1 comprises a multi-axis force sensor 120 configured to determine the force(s) acting on the wire 101. The apparatus 1 comprises a controller 130 adapted to control at least one of the following: the output power of the laser source 300, the relative movement speed of the wire nozzle 100 and the laser beam 301 relative to the substrate 200, or the position of the wire 101 and / or wire nozzle 100 relative to the laser beam 301 in at least one axis.

[0020] Improved process control is achieved by controlling the output parameters of the laser metal deposition apparatus 1 based on the force measured by the force sensor 120.

[0021] The apparatus 1 of FIG. 1 preferably comprises an actuator 110 operably connected to the wire nozzle 100 for positioning the wire nozzle 100, the wire 101, and / or the wire tip 102 relative to the laser beam 301. The actuator 110 is configured to displace the wire tip 102, the wire 101, and / or the wire nozzle 100 in at least one axis. The controller 130 and the actuator 110 position the wire tip 102, the wire nozzle 100, and / or the wire 101 based on the force measured by the force sensor 120.

[0022] Improved deposition is achieved by controlling the position of the wire 101 relative to the laser beam 301 based on the force acting on the wire 101, and relatively thin deposition beads can be reliably achieved compared to an apparatus where the wire and the laser beam move cooperatively relative to the substrate 200.

[0023] As described above, the wire nozzle 100 supplies the wire such that the wire 101 can be melted on the substrate 200 and deposited on the substrate 200. The wire nozzle 100 may also be known as a wire supply device 100. Typically, the wire nozzle 100 supplies a coiled spool of the wire 101. Since the wire is provided on the spool, the wire exiting the wire nozzle 100 may have a slight curvature. When depositing a relatively thick bead on the substrate 200, such a curvature of the wire typically does not pose a problem because the wire can be maintained within a relatively large laser beam 301 or a relatively large melt pool 202. However, in a deposition process that requires deposition of a relatively thin bead, such as less than about 2 mm, the curvature of the wire 101 can lead to the wire being inadvertently displaced relative to the laser beam 301. The present apparatus 1 can adjust the deposition process and can be utilized, for example, for reliable deposition of beads of relatively thin materials.

[0024] The wire 101 may have any suitable cross-section for laser metal wire deposition. For example, the wire 101 may have a circular or rectangular cross-section. A wire 101 having a rectangular cross-section may be referred to in this art as a strip or band.

[0025] The actuator 110 is configured to displace the wire tip 102, the wire 101, and / or the wire nozzle 100 relative to the laser beam 301 on at least one axis. The single axis is advantageously the Z-axis, but the actuator 110 can control the displacement on the X-axis, Y-axis, or rotation axis. The actuator 110 may be a multi-axis actuator 110 configured to move the wire nozzle 100 and / or the wire 101 on at least two axes. The multi-axis actuator 110 may be, for example, a ZX-axis, ZY-axis or XY-axis actuator, or a Z-axis and rotation axis actuator 110, or any combination thereof. The multi-axis actuator 110 may be a three-axis, XYZ-axis actuator configured to displace the wire 101 relative to the laser beam 301 on at least three axes. In particular, the actuator 110 is configured to displace the tip 102 of the wire 101 relative to the laser beam 301. The actuator 110 positions the wire tip 102 relative to the laser beam 301. Clearly, since the displacement of the wire 101 or wire nozzle 100 essentially displaces the wire tip 102, the positioning of the wire tip 102 can be achieved by displacing the wire 101 and / or wire nozzle 100. It is advantageous for the actuator 110 to be mounted on the wire nozzle 100 so that the wire nozzle 100 is displaced to displace and position the wire 101, in particular the wire tip 102. By mounting the actuator on the wire nozzle 100, precise control of the position of the wire 101 is achieved without requiring additional components to actuate / hold the wire 101. As described, the actuator 110 is configured to displace the wire 101, in particular the wire tip 102, along the Z-axis direction, for example, as shown in Figure 1. The Z-axis is approximately vertical and approximately parallel to the laser beam 301. The ZY multi-axis actuator 110 is configured to displace the wire 101, in particular the wire tip 102, along the Z-axis and Y-axis directions, as shown in Figure 1. The Y-axis points inward (towards the page) in Figure 1.The ZX multi-axis actuator 110 is configured to displace the wire 101 and the wire tip 102 laterally relative to the laser beam 301. The ZX multi-axis actuator 110 is configured to displace the wire 101, and in particular the wire tip 102, along the Z-axis and X-axis as shown in Figure 1. The X-axis is the direction of travel in the process schematically shown in Figure 1. Using the multi-axis actuator, combinations of control along the X-axis, Y-axis, Z-axis, and / or rotation axis are possible. The wire feeder / nozzle of a typical laser deposition apparatus can only control the wire feeding speed. That is, in a typical known apparatus, the wire is fed from the wire feeder at individual speeds. Displacement of the wire 101 and wire tip 102 relative to the laser beam 301 has been shown to provide an improved deposition process, especially based on measured forces.

[0026] As described, the additive manufacturing apparatus 1 may include, in addition to the wire nozzle 100 mechanism for controlling the wire supply speed 101, a separate actuator 110. Controlling only the supply speed is not sufficient to overcome the problems related to wire displacement during deposition.

[0027] As described above, in addition to displacement within the three axes, the wire 101 may be rotationally displaceable relative to the laser beam 301 and / or the substrate 200. That is, the wire 101 may be displaceable around a rotation axis. The rotational displacement of the wire 101 can be achieved by controlling the rotation axis of the robot arm to which the wire nozzle 100 is attached. Advantageously, the wire 101 may be rotationally displaceable around the Z-axis, which corresponds to the incidence axis of the laser beam 301. The position of the wire 101 may be rotatable relative to the substrate 200. The wire 101 may be rotatable around the Y-axis, which is the transverse axis, as shown in Figure 1. The rotational displacement of the wire 101 is controlled based on a force measured by the force sensor 120.

[0028] Ideally, the laser source 300 and wire nozzle 100 have six degrees of freedom to enable the production of parts with complex geometric shapes. As described above, the wire 101 has an additional degree of freedom relative to the laser beam 301 by the actuator 110.

[0029] As described above in conventional laser metal deposition apparatuses, the laser beam 301 and wire nozzle 100 are configured to move together with respect to the substrate. This can be achieved by placing the laser source 300 and wire nozzle 100 on a movable gantry or robotic arm that moves relative to the substrate, or by placing the substrate 200 on a movable stage / platform that can move relative to a fixed laser source 300 and wire nozzle 100, or a combination of both a movable robot / gantry and a movable substrate. The term configured to move relative to the substrate includes both the actuation of the laser source 300 and wire nozzle 100 relative to the substrate, and the actuation of the substrate 200 relative to the laser source 300 and wire nozzle 100. In this laser metal deposition apparatus 1, the laser beam 301 and wire nozzle 100 are advantageously configured to move relative to the substrate 200, and the wire 101 is displaceable relative to the laser beam 301 based on force feedback.

[0030] The actuator 110 and the laser source 300 may be provided in a fixed relationship with respect to each other. For example, the actuator 110 and the laser source 300 may be provided at the distal end of a robot arm, i.e., the positionable end. The robot arm to which the actuator 110 and the laser source 300 are provided can move relative to the substrate 200. As described above, the substrate 200 may be movable relative to the fixed laser source 300, in which case the laser source 300 and the actuator 110 are in a fixed relationship with respect to each other and fixed in a single position, but the substrate 200 is movable at least in the XY axes relative to the fixed positions of the actuator 110 and the laser source 300. When the actuator 110 is actuated to displace the wire nozzle 100, it has elements that are displaceable relative to each other, which means that not all components of the actuator 110 need to be in a fixed relationship with the laser source 300. The actuator 110 has at least one fixed element 111 and at least one displaceable element 112 that is displaceable relative to the fixed element 111. Therefore, the laser source 300 can be considered to be in a fixed relationship with the fixed element 111 of the actuator 110. The fixed element 111 of the actuator defines the position of the actuator 110 relative to the laser source 300, and the displaceable element 112 defines the position of the wire nozzle 100 relative to the laser beam 301.

[0031] The multi-axis force sensor 120 is configured to measure the force acting on the wire 101, particularly the wire tip 102. The multi-axis force sensor may be a force sensor 120 that detects force components in at least two axes. The multi-axis force sensor 120 may detect force components in the XY axis, XZ axis, YX axis, and / or YZ axis. Advantageously, the multi-axis force sensor 120 is a tri-axis (XYZ tri-axis) force sensor configured to measure the force acting on the wire 101, particularly the wire tip 102.

[0032] Multi-axis force sensors enable improved process control beyond single-axis force sensors, as single-axis sensors alone have been shown to be insufficient for accurately determining changes from optimal deposition conditions. For example, when the wire tip 102 moves laterally away from the molten pool 202, there may not be a significant difference in the Z-axis force. However, by combining measurements from the Z and Y axes, such lateral displacements of the wire tip 102 can be detected, allowing for adjustment of output parameters to restore optimal process conditions.

[0033] The multi-axis force sensor 120 may, advantageously, be provided on the wire nozzle 100. The multi-axis force sensor 120 may, advantageously, be provided near the output tip 104 of the wire nozzle 100. In such an arrangement, the multi-axis force sensor 120 indirectly measures the force acting on the wire 101 by measuring the force(s) acting on the wire nozzle 100. In some cases, the multi-axis force sensor 120 may be provided as an additional component between the output nozzle and the wire tip 102 of the wire nozzle 100. In such an arrangement, the wire 101 is directly connected to the force sensor 120, and the force(s) acting on the wire 101 is directly measured by the force sensor 120.

[0034] The multi-axis force sensor 120 has been shown to be particularly advantageous for detecting multiple independent or interdependent harmful process modes, such as runaway (described below) and / or stubs. The multi-axis force sensor 120 has been shown to be particularly advantageous in complex deposition processes, such as deposition on a non-planar substrate, where forces with components in different directions act on the wire 101 and / or wire nozzle 100.

[0035] For example, a harmful process mode is known as "runaway." The term "runaway" refers to a case where the wire tip 102 deviates laterally (Y-axis in Figure 1) from the molten pool. The wire tip 102 may partially deviate from the molten pool 202 or completely detach. The deposition of wire 101 on a non-flat substrate surface 201, such as a substrate with a convex or concave substrate surface 201, can be particularly susceptible to such harmful runaway process modes because the downward force of the wire 101 toward the non-flat substrate surface 201 applies a lateral force to the wire tip 102. A multi-axis force sensor 120 can detect such runaway process modes by measuring multiple force components.

[0036] The force sensor 120 is connected to the controller 130. The force sensor 120 is an input parameter to the controller 130.

[0037] The multi-axis force sensor 120 can be any known component(s) suitable for measuring the force at the wire tip 102. The multi-axis force sensor 120 could be, for example, a tri-axis strain sensor.

[0038] The multi-axis actuator 110 and the multi-axis force sensor 120 may be incorporated into a single component located at the attachment point of the wire nozzle 100 to the gantry / robot arm.

[0039] The controller 130 may be configured to control the thermal energy provided by the laser source 300, the wire 101 current for wire heating. The controller 130 may be adapted to control the deposition rate based on a measured force, which is the relative movement speed of the wire nozzle 100 and the laser beam 301 relative to the substrate 200. As described above, the controller 130 may be adapted to control the displacement of the wire 101 and / or wire nozzle 100 relative to the laser beam 301 in at least one axis.

[0040] The controller 130 may be configured to control the actuator 110, and in addition to the actuator 110, it may be configured to control the thermal energy provided by the laser source 300 and the wire current for wire heating 101. The controller 130 may be adapted to control the deposition rate based on a measured force(s) or force(s). The controller 130 may be configured to control the displacement velocity of the wire nozzle 100 and the laser source 300 relative to the substrate 200 based on a measured force(s).

[0041] By controlling the output parameters in addition to the positions of the wire 101, the wire tip 102, and / or the actuator 110, improved process control is achievable, resulting in an improved deposition process.

[0042] The controller 130 is configured to control the actuator 110 and other output parameters based on the force measured by the multi-axis force sensor 120. The controller 130 implements force feedback-based control of the deposition process. The controller 130 may be a P- / PI- / PID-feedback controller 130. Other control techniques suitable for controlling the actuator 110 and / or other output parameters such as laser thermal energy based on the force measured by the multi-axis force sensor 120, such as bang-bang, sliding mode, excitation signal, etc., may be utilized. The controller 130 may be implemented by devices known in the art. For example, the controller 130 may be implemented by a field-programmable gate array (FPGA), a microcontroller, a system on a chip (SoC), a single-board computer, a programmable logic controller (PLC), a personal computer (PC), or a combination thereof.

[0043] The controller 130 may be configured to control the actuator 110 based on the implementation of one type of force feedback, such as P / PI / PID feedback, and to control other parameters, such as laser thermal energy, based on the implementation of different force feedback controls, such as sliding mode. In other words, an ideal combination of force feedback implementations for a particular output parameter is possible.

[0044] If the controller 130 controls only the actuator 110 based on the measured force, the controller 130 may be mounted on a device exclusively connected to the actuator 110 and the force sensor 120. If the controller 130 controls other output parameters in addition to the position of the wire nozzle 100 and / or wire 101, the controller 130 may be mounted on a device connected to inputs / outputs that control and / or measure laser output, wire current, wire feed rate, XYZ position of the laser and wire nozzle relative to the substrate, wire conductance, etc., in addition to the actuator 110 and the force sensor 120.

[0045] Generally, when the deposition process is initiated, the wire tip 102 is positioned at a designated known position within the laser beam 301. The controller 130 may be configured to initiate force feedback control of the position of the wire tip 102 at the start of the deposition process and / or during steady-state operation, i.e., while deposition is taking place.

[0046] The laser source 300 is a high-energy laser source 300 capable of providing a laser beam 301 with sufficient energy to melt the wire 101 and / or the substrate 200. The laser beam 301 forms a molten pool 202 on the surface 201 of the substrate 200. The surface 201 of the substrate 200 can take on various shapes such as flat, convex, or concave, depending on the deposition process and the (intended) part to be deposited.

[0047] The following describes how to operate the laser metal deposition apparatus (see Figure 2). A wire 101 to be deposited on the substrate 200 is supplied via a wire nozzle 100 (1000). A laser beam 301 is supplied to the substrate 200 and the wire 101, particularly to the wire tip 102 of the wire 101 (2000). The laser beam 301 melts a portion of the substrate 200 and the wire 101, forming a molten pool 202 on the surface 201 of the substrate 200. Thermal energy from the laser beam 301 and / or the molten pool 202 melts the wire tip 102. The wire 101 and the laser beam 301 are displaced relative to the substrate 200 (3000). This displacement (3000) occurs in the direction of travel, i.e., the direction along the substrate 200 on which the deposited metal is to be deposited. The force acting on the wire 101 in multiple axes is measured via a multi-axis force sensor 120 (4000). Based on the force measured by the force sensor 120, control at least one of the following: the output power of the laser source 300, the current supplied to the wire 101 for wire heating, the relative movement speed of the wire nozzle 100 and the laser beam 301 relative to the substrate 200, or the position of the wire 101 and / or wire nozzle 100 relative to the laser beam 301 in at least one axis (5000). This method may advantageously include displacing the wire 101 relative to the laser beam 301 using an actuator 110 actuated to the wire nozzle 100 based on the force measured by the multi-axis force sensor 120 (6000). The deposition of the wire 101 is performed simultaneously with the measurement (4000) and control (5000). That is, displacing the wire 101 and the laser beam 301 relative to the substrate 200 (3000) is performed simultaneously with the measurement (4000) and control (5000). This method may further include displacing the wire nozzle 100 and / or wire 101 via the actuator 110 based on a force measured by a force sensor (6000), and controlling at least one of the output power of the laser source 300, the current supplied to the wire 101 for wire heating, and the relative moving speed of the wire nozzle 100 and the laser beam 301 with respect to the substrate 200 (5000).Displacement of the wire 101 and the wire nozzle 100 (6000) can occur in at least two axes.

[0048] As described above, apparatus 1 is particularly suitable for a method of detecting and recovering from harmful process modes. A method for detecting and recovering from harmful process modes / conditions, such as stub or runaway, includes each of the processes and optional process steps detailed above. A method for detecting and recovering from harmful process modes may include the step of detecting a harmful process mode based on the force acting on the wire 101 measured by the multi-axis force sensor 120.

[0049] The multi-axis force sensor 120 can be advantageously combined with additional detector components to detect other parameters of the deposition process. As those skilled in the art will understand, a laser metal deposition apparatus typically receives input data relating to the power of the laser 300, the feed rate of the wire 101, and the position of the substrate 200. Each of these parameters can be detected, individually or ideally in combination, and provided as input to the controller 130. The force-based control process and apparatus 1 described herein can be advantageously combined with the conductance-based control system and apparatus described in International Publication WO2021 / 110793(A1) (Procada AB). That is, the controller 130 can receive parameters representing the conductance measured between the wire tip 102 and the substrate 200, in addition to the force detected via the multi-axis force sensor 120. The controller 130 can advantageously combine the measured conductance with the force measured by the multi-axis force sensor 120 to maintain process stability or recover from one or more harmful process modes. [Examples]

[0050] [Experimental Results] [Experiment 1: Deposition results using XYZ position actuators] This method was successfully used to deposit titanium alloys, nickel alloys, and steel alloys in thin layers (approximately 200 μm thick). The thin layers and the resulting shallow molten pools made the process overly sensitive to variations in the distance between the wire and the substrate, posing a significant risk of stub formation. Force measurements provided by the multi-axis force sensor 120 enabled automatic detection and appropriate mitigation of initial stubs using XYZ wire position actuators.

[0051] This method has been successfully used to detect undesirable mechanical interactions between wires and substrates, enabling automated process control.

[0052] [Experiment 2: Detection of harmful process modes using a multi-axis force sensor] Trials were conducted to evaluate the multi-axis force sensor 120 and to demonstrate control using multi-axis force control. The height (Z-axis) controller was intentionally controlled to be unstable. The controller also received conductance data from the conductance detection and control system. The results of the trials are shown in Figure 4. The forces measured in the Z and Y axes are shown in the graph. The force in the X axis was measured during the trials and used for control purposes, but is not relevant to evaluating the results of these trials.

[0053] Arrow A indicates the expected behavior of the process. As the height of the wire 101 relative to the substrate 200 increases, the conductance value decreases, i.e., the contact of the wire 101 with the substrate 200 decreases. The Y / Z force remains near 0 N (zero Newtons) as the wire 101 moves away from the substrate, and there is no difference in the detected force. When conductance decreases, the conductance aspect (or viewpoint) of the control system tends to change the parameter to increase conductance, in this case, Z height was decreased to increase conductance. This change can be seen in the graph of Z height after the peak (after arrow A) which shows the wire displacing toward the substrate. The decrease in Z height is expected to result in an increase in conductance as the "wetting neck" in the molten pool 202 thickens. This increase in conductance can be seen when Z height reaches its maximum and begins to descend before arrow B. However, during the decrease in Z height, wire 101 experiences a runaway, harmful process mode.

[0054] Arrow B indicates a sharp change to a lower conductance value, which is due to a runaway wire. The y-force became too high, causing the wire to partially or completely leave the molten pool. Force measurement data shows that both the Z-force and the Y-force deviated from the 0 N (zero Newton) line.

[0055] Arrow C indicates where process force control allows the process to re-stabilize by disallowing the height controller to move the actuator downward, which would further reduce the Z height. In this particular case, the increase in the Y component of the force indicates that the harmful process mode was a runaway wire and not just a stub, i.e., the wire moved laterally within or even outside the molten pool 202. Control of the Y, ZY, XY, and / or XYZ positions of the wire 101 or wire nozzle 100 relative to the laser beam 301 would also be a possible control action based on the increasing Y force component.

[0056] Although the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the specific forms described herein. Rather, the present invention is limited only by the appended claims.

[0057] In the claims, the term “comprises / comprising” does not exclude the existence of other elements or steps. Furthermore, multiple means, elements, or method steps, while listed individually, may be implemented, for example, by a single unit or processor. Moreover, individual features may be included in different claims, but these may be advantageously combined in some cases, and inclusion in different claims does not mean that the combination of features is unfeasible and / or unfavorable. In addition, a singular referent does not exclude a plural. Terms such as “a,” “an,” “first,” and “second” do not exclude a plural. Reference numerals in the claims are provided merely as clear examples and should never be construed as limiting the scope of the claims. [Explanation of Symbols]

[0058] 1. Laser metal deposition apparatus 100 Wire Nozzles 101 Wire 110 Multi-axis actuator 111 Actuator fixing element 112 Displaceable elements of actuators 120 Multi-axis force sensors 130 Controllers 200 circuit boards 300 laser sources 301 Laser beam

Claims

1. A wire nozzle (100) for feeding out wires (101) to be deposited on a substrate (200), A laser source (300) for sending out a laser beam (301) configured to melt the aforementioned wire, A multi-axis force sensor (120) configured to determine the force between the wire (101) and the substrate (200), A controller (130) is configured to control at least one of the following based on the force measured by the multi-axis force sensor (120): the output power of the laser source (300), the relative movement speed of the wire nozzle (100) and the laser beam (301) with respect to the substrate (200), or the displacement of the wire (101) and / or the wire nozzle (100) with respect to the laser beam (301) in at least one axis; A laser metal deposition apparatus (1) is provided with the following features.

2. The laser metal deposition apparatus (1) includes an actuator (110) which is operatively connected to the wire nozzle (100) and configured to displace the wire nozzle (100) and / or the wire (101) in at least one axis relative to the laser beam (301), The actuator (110) is controlled by the controller (130) based on the force measured by the multi-axis force sensor (120), as described in claim 1, for the laser metal deposition apparatus (1).

3. The laser metal deposition apparatus (1) according to claim 2, wherein the actuator is a multi-axis actuator (110) configured to displace the wire nozzle (100) and / or the wire (101) in at least two axes relative to the laser beam (301).

4. The laser metal deposition apparatus (1) according to claim 2 or 3, wherein the actuator (110) is configured to displace the wire nozzle (100) and / or the wire (101) with respect to the laser beam (301) at least in the Z-axis.

5. The laser metal deposition apparatus (1) according to claim 3 or 4, wherein the multi-axis actuator (110) is a three-axis or more actuator configured to displace the wire (101) in at least three axes.

6. The controller (130) is configured to control the position of the wire nozzle (100) relative to the laser beam (301) in at least one axis, Furthermore, the laser metal deposition apparatus (1) according to any one of claims 1 to 5 is configured to control at least one of the following: the output power of the laser source (300), the current supplied to the wire (101), or the relative movement speed of the wire nozzle (100) and the laser beam (301) with respect to the substrate (200).

7. The laser metal deposition apparatus (1) according to any one of claims 1 to 6, wherein the multi-axis force sensor (120) is a three-axis (XYZ three-axis) force sensor.

8. The laser source (300) and the fixing element (111) of the actuator (110) are fixed to each other. The laser metal deposition apparatus (1) according to any one of claims 2 to 7, wherein the actuator (110) and the laser source (300) are configured to move relative to the substrate (200) in at least two XY axes.

9. The laser metal deposition apparatus (1) according to any one of claims 1 to 8, wherein the multi-axis force sensor (120) is provided on the wire nozzle (100) so as to be able to measure the force acting on the wire nozzle (100).

10. The laser metal deposition apparatus (1) according to any one of claims 2 to 9, wherein the actuator (110) is provided separately from and in addition to the wire nozzle (100) for controlling the supply speed of the wire (101).

11. Based on the measured force, in addition to controlling at least one of the following: the output power of the laser source (300), the relative movement speed of the wire nozzle (100) and the laser beam (301) with respect to the substrate (200), or the displacement of the wire (101) and / or the wire nozzle (100) with respect to the laser beam (301) in at least one axis, The laser metal deposition apparatus (1) according to any one of claims 1 to 10, wherein the controller (130) is configured to control the current supplied to the wire (101) based on the measured force.

12. The laser metal deposition apparatus (1) according to any one of claims 1 to 11, wherein the controller (130) is configured to control, in addition to controlling the actuator (110), at least one of the heat provided by the laser source (300), the current to the wire (101), and the relative moving speed of the wire nozzle (100) and the laser beam (301) with respect to the substrate (200), based on the measured force.

13. A method for operating a laser metal deposition apparatus (1), The wire (101) to be deposited on the substrate (200) is provided via the wire nozzle (100) (1000). A laser beam (301) is provided to the substrate (200) via the laser source (300) (2000). In order to deposit the molten wire in the direction of travel, the wire (101) and the laser beam (301) are displaced relative to the substrate (200) (3000). The force acting on the wire (101) in multiple axes is measured via a multi-axis force sensor (120) (4000), and, Based on the force measured by the multi-axis force sensor (120), control at least one of the following: the output power of the laser source (300), the relative movement speed of the wire nozzle (100) and the laser beam (301) with respect to the substrate (200), or the position of the wire (101) and / or the wire nozzle (100) with respect to the laser beam (301) in at least one axis (5000). Methods that include...

14. Controlling based on the force measured by the multi-axis force sensor (120) (5000) The method includes displacing the wire (101) and / or the wire nozzle (100) in at least one axis relative to the laser beam (301) via an actuator (110) that is actuarily connected to the wire nozzle (100), A method for operating the laser metal deposition apparatus (1) according to claim 13.

15. The method according to claim 14, wherein the displacement of the wire (101) and / or the wire nozzle (100) relative to the laser beam (301) via the actuator (110) (6000) is performed in at least two axes.

16. The method according to claim 14 or 15, wherein controlling (5000) based on the force measured by the multi-axis force sensor (120) further includes controlling at least one of the output power of the laser source (300), the current supplied to the wire (101), or the relative moving speed of the wire nozzle (100) and the laser beam (301) with respect to the substrate (200).

17. The method according to any one of claims 14 to 16, wherein the actuator (110) is configured to displace the wire nozzle (100) relative to the laser beam (301).

18. The method according to any one of claims 13 to 17, wherein the multi-axis force sensor (120) is provided on the wire nozzle (100).

19. The method according to any one of claims 13 to 18, wherein measuring the force acting on the wire (4000) and displacing the wire with respect to the laser beam (301) (5000) are performed simultaneously with displacing the wire (101) with respect to the substrate (200) (3000).

20. In addition to controlling at least one of the following based on the measured force: the output power of the laser source (300), the relative movement speed of the wire nozzle (100) and the laser beam (301) with respect to the substrate (200), or the displacement of the wire (101) and / or the wire nozzle (100) with respect to the laser beam (301) in at least one axis (5000), The controller (130) is configured to control the current supplied to the wire (101) based on the measured force. The method according to any one of claims 13 to 19.

21. A method for detecting and recovering a harmful process mode in a laser metal deposition apparatus (1), wherein the laser metal deposition apparatus (1) comprises a wire nozzle (100) for providing wires (101) to be deposited on a substrate (200) and a laser source (300) for providing a laser beam (301), and the method is as follows: The force acting on the wire (101) in multiple axes is measured via a multi-axis force sensor (120), and, Based on the force measured by the multi-axis force sensor (120), control at least one of the following: the output power of the laser source (300), the current supplied to the wire (101), the relative movement speed of the wire nozzle (100) and the laser beam (301) with respect to the substrate (200), or the position of the wire nozzle (100) with respect to the laser beam (300) in at least one axis. Methods that include...

22. The method according to claim 21, wherein the harmful process mode is stub and / or runaway.

Images