Lamination molding system

Abstract

This lamination molding system (1) comprises a welding torch (20), a robot arm (40), a welding power supply (10), and a control device (30). A weld bead (70) includes an arc start part which is the start position of lamination. The control device (30) sets the welding current of the arc start part of a layer to be laminated this time on the basis of the number of laminated layers at a layer immediately preceding the layer to be laminated this time.

Description

Additive Manufacturing System

[0001] The present disclosure relates to additive manufacturing systems.

[0002] Japanese Patent Laid-Open Publication No. 2022-106172 (Patent Document 1) discloses a method for forming a shaped object by stacking weld beads, and changing the welding conditions if the height of the weld bead deviates from the planned height. In Japanese Patent Laid-Open Publication No. 2022-106172 (Patent Document 1), a consumable electrode is used when stacking the weld beads, and the welding speed is changed depending on the stack height.

[0003] Japanese Patent Application Laid-Open No. 2022-106172

[0004] Here, a weld bead of one layer includes an arc start portion, which is the start position of lamination, a steady portion formed after the arc start portion, and an arc end portion, which is the end position of lamination. The arc start portion tends to have a high lamination height because the heat input, which is the amount of heat applied to the molten part from the outside, is insufficient, and the heat easily escapes and does not spread.

[0005] The technology of JP 2022-106172 A (Patent Document 1) is effective when the difference in height between the arc start portion and the steady portion is small, but when the difference in height is large, adjusting the welding speed alone is insufficient. In the first place, in order to stably build up the weld bead, it is desirable to avoid creating a difference in height between the arc start portion and the steady portion.

[0006] An object of the present disclosure is to provide a technique that allows stable deposition of weld beads when using a consumable electrode wire.

[0007] The present disclosure relates to an additive manufacturing system that supplies a welding current to a consumable electrode wire and builds up a weld bead in multiple layers to manufacture a shaped object. The additive manufacturing system includes a welding torch that builds up a weld bead using a consumable electrode wire, a drive unit that moves the welding torch based on a preset or calculated welding speed, a welding power source that supplies the welding current to the consumable electrode wire, and a control unit that controls the welding power source and the drive unit. The weld bead includes an arc start portion, which is the starting position of the buildup. The control unit sets at least one of the welding current or welding speed of the arc start portion of the layer to be currently built based on the number of layers or the temperature of the layer immediately preceding the layer to be currently built.

[0008] In the additive manufacturing system disclosed herein, at least one of the welding current and welding speed for the layer to be currently laminated is set based on the number of layers or the temperature of the layer immediately preceding the layer to be currently laminated. This allows the state of the arc start portion of the layer to be currently laminated to be changed depending on the state of the layer immediately preceding the layer to be currently laminated, thereby enabling stable lamination of a weld bead when using a consumable electrode wire.

[0009] FIG. 1 is a diagram schematically illustrating an additive manufacturing system according to embodiment 1. FIG. 2 is a diagram for explaining the relationship between the name of each part of a weld bead and the welding current. FIG. 3 is a diagram explaining the welding current and the shape of the arc start portion according to comparative example 1. FIG. 4 is a diagram explaining the welding current and the shape of the arc start portion according to comparative example 2. FIG. 5 is a diagram explaining the welding current and the shape of the arc start portion according to embodiment 1. FIG. 6 is a flowchart showing control details according to embodiment 1. FIG. 7 is a diagram showing changes in welding speed according to embodiment 2. FIG. 8 is a diagram schematically illustrating an additive manufacturing system according to embodiment 3. FIG. 9 is a diagram showing changes in welding current according to embodiment 3.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0011] 1 is a diagram schematically illustrating an additive manufacturing system 1 according to embodiment 1. The additive manufacturing system 1 includes a robot arm 40, a welding torch 20, a welding power source 10, a wire feeder 50, and a control device 30.

[0012] The robot arm 40 is a multi-joint arm, for example, a six-axis multi-joint arm. The robot arm 40 functions as a drive device that moves the welding torch 20 at a preset or calculated welding speed. As the robot arm 40 moves the welding torch 20, a weld bead 70 formed by melting the consumable electrode wire 51 is deposited. The robot arm 40 is controlled by the control device 30 so that a shaped object is formed by depositing the weld beads 70. The layer deposited immediately before the layer on which the current weld bead 70 is deposited is referred to as the previous layer.

[0013] In the welding torch 20, a welding current is supplied to the consumable electrode wire 51 at a power supply tip (not shown) located inside the nozzle 21. The consumable electrode wire 51 melts due to the arc generated between the consumable electrode wire 51 and the base material 80 or the already deposited weld bead 70 and resistance heat generated by the current flow. The melting of the consumable electrode wire 51 forms the weld bead 70. The welding torch 20 deposits the weld bead 70 using the consumable electrode wire 51. A shielding gas supply (not shown) supplies a shielding gas to the welding torch 20, which exits the nozzle 21 and reaches the arc 22 and the weld zone. The shielding gas may be, for example, argon, CO ２ and the like, and mixed gases containing these are used.

[0014] Torch cable 11 connected to welding torch 20 contains a cable for current supplied from welding power source 10, a consumable electrode wire 51 fed from wire feeder 50, and piping for shielding gas supplied from a shielding gas supply unit (not shown).

[0015] Welding power source 10 supplies AC as a welding current to consumable electrode wire 51. The magnitude of the welding current output from welding power source 10 is set by control device 30. Wire feeder 50 includes a roller and a motor (not shown). Wire feeder 50 feeds consumable electrode wire 51 to welding torch 20 by driving the motor to rotate the roller. The operation of wire feeder 50 is controlled by welding power source 10 based on commands from control device 30. The operation of wire feeder 50 may also be controlled directly by welding power source 10.

[0016] The control device 30 includes an arithmetic unit 31, a memory 32, a storage device 33, and an input / output interface 34. These components are connected via a bus.

[0017] The arithmetic device 31 is a computing entity (computer) that executes predetermined processing. The arithmetic device 31 is configured with a processor such as a central processing unit (CPU), a micro-processing unit (MPU), a tensor processing unit (TPU), or a graphics processing unit (GPU). The arithmetic device 31 can also be interpreted as a processing circuitry that executes predetermined processing.

[0018] The memory 32 includes a storage area (for example, a working area) for storing program code or work memory when the arithmetic unit 31 executes various programs.

[0019] The storage device 33 functions as a storage unit that stores various programs or various data executed by the arithmetic device 31. For example, the storage device 33 stores a control program 330 executed by the arithmetic device 31.

[0020] The input / output interface 34 receives input of various data and outputs data obtained by various processes in accordance with instructions from the arithmetic unit 31.

[0021] The additive manufacturing system 1 supplies a welding current to the consumable electrode wire 51 and builds up multiple layers of weld beads 70 to manufacture a model. In the additive manufacturing system 1, the control device 30 controls the welding current output from the welding power source 10. In the additive manufacturing system 1, the control device 30 controls the welding speed by driving the robot arm 40. The control device 30 controls, for example, the operation of the robot arm 40.

[0022] The weld bead 70 and the welding current will now be described in detail. FIG. 2 is a diagram illustrating the relationship between the names of each part of the weld bead 70 and the welding current. FIG. 2(A) shows the names of each part of the weld bead 70, and FIG. 2(B) shows the welding current set for each part of the weld bead 70. As shown in FIG. 2(A), the weld bead 70 is layered on a base material 80. The weld bead 70 includes an arc start portion, which is the start position of layering, a steady portion formed after the arc start portion, and an arc end portion, which is the end position of layering.

[0023] The arc start portion is set to, for example, an arc start distance Ls, which is, for example, about twice the bead width w, which is the length of the weld bead 70 in the width direction.

[0024] In the additive manufacturing system 1, the control device 30 controls the movement of the welding torch 20 so that at least a portion of the arc start portions overlap in the stacking direction (height direction of the weld bead 70). However, in the additive manufacturing system 1, the stacking may be performed so that the arc start portions do not overlap.

[0025] As shown in Figure 2(B), the welding current set in the arc start section is referred to as the initial current Is, and the welding current set in the steady section is referred to as the steady current Iset. The arc start section is the section where the buildup of the weld bead 70 begins, and because heat is easily dissipated and the weld does not spread, the buildup height tends to be high. For this reason, the initial current Is is set to a value greater than the steady current Iset. Note that the magnitudes of the initial current Is and steady current Iset may change during welding, but here we will explain the case where they are constant.

[0026] 3A and 3B are diagrams illustrating the welding current and arc start portion according to Comparative Example 1. Fig. 3A shows the relationship between the number of layers and the welding current, and Fig. 3B shows the shape of the arc start portion when layering is performed with the welding current of Fig. 3A.

[0027] In Comparative Example 1, as shown in Fig. 3A, the initial current Is is set to the same value as the steady-state current Iset regardless of the number of layers, and the steady-state current Iset is always fixed and supplied to the arc start portion regardless of the number of layers in the weld bead 70. In the case of Comparative Example 1, because the initial current Is is fixed to the same value as the steady-state current Iset even when the number of layers increases, as shown in Fig. 3B, the heat input to the arc start portion is insufficient, preventing wetting and spreading, and resulting in an increase in the layer height.

[0028] 4A and 4B are diagrams illustrating the welding current and arc start portion according to Comparative Example 2. Fig. 4A shows the relationship between the number of layers and the welding current, and Fig. 4B shows the shape of the arc start portion when layering is performed with the welding current of Fig. 4A.

[0029] In Comparative Example 2, as shown in FIG. 4A, the initial current Is is set to a value greater than the steady-state current Iset regardless of the number of layers, and a fixed welding current greater than the steady-state current Iset is always supplied to the arc start portion regardless of the number of layers in the weld bead 70. In the case of Comparative Example 2, the initial current Is is fixed at a value greater than the steady-state current Iset even as the number of layers increases, so the temperature of the arc start portion increases as the layer becomes higher, where heat is less easily transferred to the base metal. For this reason, in Comparative Example 2, as shown in FIG. 4B, there is a possibility that the weld bead 70 will melt away as the number of layers in the arc start portion increases.

[0030] Comparative Examples 1 and 2 are summarized below. To reduce the difference in lamination height between the arc start portion and the steady-state portion, it is conceivable to improve the wetting spread of the arc start portion by increasing the initial current Is greater than the steady-state current Iset. However, if Is is set to the same value for all layers, an Is adjusted to the lower layers will result in excessive heat input to the upper layers, due to the tendency for heat to accumulate in the weld bead 70 as the number of laminations increases. Conversely, if Is is adjusted to the upper layers, insufficient heat input will occur in the lower layers, resulting in a higher lamination height. Therefore, if the initial current Is is fixed between layers, the lamination height will not be stable because the tendency for heat to accumulate as the number of laminations increases is not taken into account.

[0031] 5A and 5B are diagrams illustrating the welding current and the arc start portion according to embodiment 1. Fig. 5A shows the relationship between the number of layers and the welding current, and Fig. 5B shows the shape of the arc start portion when layering is performed with the welding current of Fig. 5A.

[0032] 5A, in the first embodiment, the welding current (initial current Is) at the arc start point is reduced as the number of laminations increases from an initial current Is1 for the first layer. In the first embodiment, the initial current is set to gradually decrease from the initial current Is1 for the first layer to an initial current Is2 for the (ns2)th layer. The (ns2)th layer is the layer where the decrease in initial current saturates, and is set in advance based on the material of the consumable electrode wire 51, the time required for arc start from the previous layer to arc start from the next layer, and the like.

[0033] Here, Is1 and Is2 may be expressed as Is1 = α·Iset and Is2 = β·Iset, where α and β have the relationship 1≦β≦α. In other words, even if the welding current Iset is changed to change the stack height or stack width, the initial currents Is1 and Is2, which are the welding currents in the arc start portion, are set to be equal to or greater than the steady-state current Iset, which is the welding current in the steady-state portion formed after the arc start portion, and Is1 is set to be equal to or greater than Is2. This makes it possible to appropriately set the initial currents Is1 and Is2 based on the steady-state current Iset.

[0034] In the first embodiment, the welding current (initial current Is) at the arc start portion of the layer to be currently laminated is set based on the number of layers in the previous layer. As a result, the welding current (initial current Is) at the arc start portion of the layer to be currently laminated changes depending on the number of layers, so that when using a consumable electrode wire 51, a weld bead 70 can be stably laminated, as shown in FIG. 5(B).

[0035] 6 is a diagram showing the change in welding current due to differences in materials according to the first embodiment. As shown in FIG. 6 , when material A is used for the consumable electrode wire 51, as the number of laminations of the weld bead 70 increases from the first layer to the (ns2A)th layer, the initial current, which is the welding current at the arc start, decreases from Is1A to Is2A. On the other hand, when material B is used for the consumable electrode wire 51, as the number of laminations of the weld bead 70 increases from the first layer to the ns2Bth layer, the initial current, which is the welding current at the arc start, decreases from Is1B to Is2B. The characteristics Is1, Is2, and the above-mentioned α and β, which are set for each material, are stored in the storage device 33.

[0036] 6, the initial current varies depending on the number of layers from the first layer until the initial current becomes constant, depending on the type of material used for the consumable electrode wire 51. In this way, by adjusting the initial current at the arc start portion depending on the characteristics of the material, such as thermal conductivity, it is possible to stably deposit the weld bead 70 when using consumable electrode wire 51 made of various materials.

[0037] The process executed by the control device 30 according to the first embodiment will be described in detail. FIG. 7 is a flowchart showing the control content according to the first embodiment. The process of the flowchart in FIG. 7 is repeatedly called as a subroutine from the main routine in the control of the control device 30 and executed. The control device 30 first checks the layering data stored in advance in the storage device 33 in step S (hereinafter simply referred to as "S") 1. Checking the layering data means, for example, checking the layering plan, such as the trajectory of the welding torch 20 for all layers that have been set in advance, and the welding current (or wire feed speed) and welding speed.

[0038] Next, as shown in FIG. 6, the control device 30 sets welding conditions according to the material used for the consumable electrode wire 51 (S2). For example, in S2, the control device 30 reads Is1 and Is2 from the storage device 33 for each material, or reads α and β and calculates and sets them from the steady-state current. Next, the control device 30 checks the current number of layers (S3). For example, the control device 30 checks the current number of layers from a preset or calculated drive position of the robot arm 40. The number of layers may be replaced with the total height of layers from the base material to the previous layer, obtained from information from a separately installed camera or sensor.

[0039] Next, the control device 30 sets the initial current of the arc start section according to the number of layers acquired in S3 (S4). Next, the control device 30 executes lamination for one layer (S5). The control device 30 executes a preset program to laminate the weld beads. Next, the control device 30 determines whether the lamination plan is complete (S6).

[0040] If the control device 30 determines that the stacking plan is complete (YES in S6), it returns the process from the subroutine to the main routine. If the control device 30 determines that the stacking plan is not complete (NO in S6), it repeats the processes of S3 to S6. By performing the processes of S3 to S6, the control device 30 can set the welding current for the arc start portion of the layer to be stacked this time based on the number of layers up to the previous layer (the current number of layers). Note that the setting of the welding current may be performed by the welding power source 10.

[0041] In the additive manufacturing system 1 of the first embodiment, the control device 30 sets the welding current for the layer to be laminated currently based on the current number of layers. This allows the state of the arc start part of the layer to be laminated currently to be changed depending on how easily heat accumulates as the layer gets taller, so that the weld bead 70 can be stably laminated when using the consumable electrode wire 51.

[0042] [Embodiment 2] A second embodiment will be described. In this embodiment, instead of setting the welding current, a welding speed is set in the additive manufacturing system 1 of embodiment 1. FIG. 8 is a diagram showing changes in the welding speed according to embodiment 2. In FIG. 8, the welding speed set in the arc start portion is referred to as an initial welding speed vs, and the welding speed set in the steady portion is referred to as a steady welding speed vset. By making the initial welding speed vs slower than in the steady portion, the heat input to the arc start portion is increased, preventing the weld height from becoming higher than in the steady portion.

[0043] In the second embodiment, the welding speed is changed depending on the number of layers, thereby stably depositing the weld bead 70 when using the consumable electrode wire 51. For example, in the second embodiment, as shown in Fig. 8, the welding speed at the arc start portion (initial welding speed vs) is increased as the number of layers increases from the initial welding speed vs1 for the first layer. In the second embodiment, the initial welding speed is set to gradually increase from the initial welding speed vs1 for the first layer to the initial welding speed vs2 for the (ns2)th layer. The (ns2)th layer is the layer where the increase in the initial welding speed saturates, and is set in advance depending on the material of the consumable electrode wire 51, etc.

[0044] Here, as in the case of the current, the initial welding speed vs may be calculated using a predetermined coefficient, so that the initial welding speed vs can be automatically determined even if the steady welding speed vset changes.

[0045] The initial welding speeds vs1 and vs2, which are the welding speeds of the arc start portion, are set to be equal to or lower than the steady welding speed vset, which is the welding speed of the steady portion formed after the arc start portion. This makes it possible to appropriately set the initial welding speeds vs1 and vs2 based on the steady welding speed vset.

[0046] In the second embodiment, the welding speed (initial welding speed vs) of the arc start portion of the layer to be laminated is set based on the number of layers up to the previous layer. As a result, the welding speed (initial welding speed vs) of the arc start portion changes depending on the number of layers, so that a weld bead 70 can be stably laminated when using a consumable electrode wire 51, as shown in FIG. 8 .

[0047] Note that the control device 30 may set both the welding current (initial current Is) and the welding speed (initial welding speed Vs) for the arc start portion of the layer to be laminated currently, based on the number of layers up to the previous layer. As shown in Figures 5(A) and 8, there is an inverse relationship between the initial current Is and the initial welding speed Vs at the arc start portion. Therefore, for example, instead of setting the initial current Is to 1.5 times, the control device 30 may set the initial current Is to 1.2 times and the initial welding speed Vs to 0.8 times.

[0048] In setting the welding speed in the second embodiment, the initial welding speed may be varied depending on the number of layers from the first layer until the initial welding speed becomes constant, depending on the type of material used for the consumable electrode wire 51. In this way, by adjusting the initial welding speed at the arc start portion depending on the characteristics of the material, such as ease of melting, it is possible to stably deposit the weld bead 70 when using consumable electrode wire 51 made of various materials.

[0049] [Embodiment 3] An additive manufacturing system 1A according to embodiment 3 will be described. Fig. 9 is a diagram schematically illustrating the additive manufacturing system 1A according to embodiment 3. The additive manufacturing system 1A according to embodiment 3 differs from the additive manufacturing system 1 according to embodiment 1 in that it includes a detection device 61.

[0050] The detection device 61 is, for example, a temperature sensor. When the weld bead 70 is being layered, the temperature sensor (detection device 61) detects the temperature of the weld bead 70 at a position T just before the layering in the welding direction indicated by the arrow in FIG. 9 . The temperature sensor (detection device 61) is preferably a non-contact sensor such as a thermal camera. Temperature information of the weld bead 70 detected by the temperature sensor (detection device 61) is transmitted to the control device 30. The temperature sensor (detection device 61) may be a pyrometer that takes images at a point rather than a thermal camera that takes images over a surface.

[0051] Control device 30 sets the welding current (initial current Is) at the arc start portion in accordance with temperature information of weld bead 70 received from temperature sensor (detection device 61). For example, as shown in Fig. 10, control device 30 sets the welding current (initial current Is) at the arc start portion of the layer to be laminated currently based on the temperature of weld bead 70 of the previous layer. Control device 30 changes the welding current (initial current Is) at the arc start portion in accordance with the material of consumable electrode wire 51.

[0052] Figure 10 shows the change in welding current due to different materials according to the third embodiment. The horizontal axis of Figure 10 represents the temperature of the weld bead 70 of the previous layer, and the vertical axis of Figure 10 represents the welding current (initial current Is) at the arc start. As shown in Figure 10, when material A is used for the consumable electrode wire 51, as the temperature of the weld bead 70 of the previous layer increases toward Ts2A, the initial current, which is the welding current at the arc start, decreases from Is1A to Is2A. On the other hand, when material B is used for the consumable electrode wire 51, as the temperature of the weld bead 70 of the previous layer increases toward Ts2B, the initial current, which is the welding current at the arc start, decreases from Is1B to Is2B.

[0053] Temperatures Ts2A and Ts2B are the layers where the decrease in initial current saturates, and are set in advance depending on the material of the consumable electrode wire 51. As shown in Fig. 10, the initial current varies at the temperature of the previous layer until the initial current becomes constant depending on the type of material used for the consumable electrode wire 51. In this way, by adjusting the initial current at the arc start portion based on the thermal conductivity and other material characteristics, it is possible to stably deposit the weld bead 70 when using consumable electrode wires 51 made of various materials.

[0054] [Modification] Instead of the process described in the third embodiment, the control device 30 may set the welding speed of the layer to be currently laminated shown in the second embodiment based on the temperature of the weld bead 70 of the previous layer. For example, the control device 30 may set the welding speed of the arc start portion of the layer to be currently laminated based on the temperature of the weld bead 70 of the previous layer. The control device 30 may set both the welding current (initial current Is) and the welding speed (initial welding speed Vs) of the arc start portion of the layer to be currently laminated based on the temperature of the weld bead 70 of the previous layer.

[0055] In the graphs shown in Figure 5 and elsewhere, the slope of the graph from the first layer to the second layer is constant, but it may be a curve, etc., and the slope of the graph does not have to be constant. Similarly, the slope of the graph shown in Figure 10 does not have to be constant, and the horizontal axis may represent the size of the molten pool of the previous layer instead of the temperature of the weld bead 70 of the previous layer.

[0056] In the above embodiment, the welding torch 20 may be moved by a Cartesian robot instead of the articulated robot arm 40 .

[0057] [Summary] (1) The present disclosure relates to an additive manufacturing system 1 (1A) that supplies a welding current to a consumable electrode wire 51 and builds up a weld bead 70 in multiple layers to manufacture a shaped object. The additive manufacturing system 1 (1A) includes a welding torch 20 that builds up the weld bead 70 using the consumable electrode wire 51, a drive device (robot arm 40) that moves the welding torch 20 based on a preset or calculated welding speed, a welding power source 10 that supplies the welding current to the consumable electrode wire 51, and a control device 30 that controls the welding power source 10 and the drive device (robot arm 40). The weld bead 70 includes an arc start portion, which is the start position of the buildup. The control device 30 sets at least one of the welding current or welding speed of the arc start portion of the layer to be currently built based on the number of layers or the temperature of the layer immediately preceding the layer to be currently built.

[0058] According to the additive manufacturing system 1 (1A) of the present disclosure, the control device 30 sets at least one of the welding current and welding speed of the arc start portion of the layer to be currently laminated based on the number of layers or the temperature of the layer immediately preceding the layer to be currently laminated. This allows the state of the arc start portion of the layer to be currently laminated to be changed depending on the state of the layer immediately preceding the layer to be currently laminated, thereby enabling stable lamination of a weld bead when using a consumable electrode wire.

[0059] (2) In the additive manufacturing system 1 of (1), the control device 30 sets the welding current of the arc start portion to be equal to or greater than the welding current of the steady portion formed after the arc start portion.

[0060] According to the additive manufacturing system 1 of the present disclosure, it is possible to set the welding current (initial current Is) at the arc start portion without making it extremely low, and to set the welding current based on the welding current at the steady portion (steady-state current Iset).

[0061] (3) In the additive manufacturing system 1 of (1) or (2), the control device 30 sets the welding speed of the arc start portion to be equal to or lower than the welding speed of the steady portion formed after the arc start portion.

[0062] According to the additive manufacturing system 1 of the present disclosure, it is possible to set the welding speed based on the welding speed in the steady state portion (steady state welding speed vset) without making the welding speed in the arc start portion (initial welding speed vs) extremely fast.

[0063] (4) In the additive manufacturing system 1 described in any one of (1) to (3), the control device 30 reduces the welding current at the arc start portion as the number of layers of the weld bead 70 increases.

[0064] According to the additive manufacturing system 1 of the present disclosure, by setting the welding current (initial current Is) of the arc start section according to the number of layers, it is possible to stably stack weld beads when using a consumable electrode wire 51.

[0065] (5) In the additive manufacturing system 1 described in any one of (1) to (4), the control device 30 increases the welding speed of the arc start portion as the number of layers of the weld bead 70 increases.

[0066] According to the additive manufacturing system 1 of the present disclosure, by setting the welding speed (initial welding speed vs) of the arc start section according to the number of layers, it is possible to stably stack weld beads when using a consumable electrode wire 51.

[0067] (6) In the additive manufacturing system 1 (1A) described in any one of (1) to (5), the control device 30 changes the welding current or welding speed of the arc start portion depending on the material of the consumable electrode wire 51.

[0068] According to the additive manufacturing system 1(A) of the present disclosure, by adjusting the welding current (initial current Is) or welding speed (initial welding speed Vs) at the arc start section depending on the characteristics of the material, it is possible to stably stack the weld bead 70 when using consumable electrode wires 51 of various materials.

[0069] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0070] 1, 1A additive manufacturing system, 10 welding power source, 20 welding torch, 21 nozzle, 30 control device, 31 arithmetic unit, 32 memory, 33 storage device, 34 input / output interface, 40 robot arm, 50 wire feeder, 51 consumable electrode wire, 61 detection device, 70 weld bead, 80 base material, 330 control program, Is, Is1, Is2 initial current, Iset steady-state current, vs, vs1, vs2 initial welding speed, vset steady-state welding speed.

Claims

1. An additive manufacturing system that supplies a welding current to a consumable electrode wire and manufactures a model by stacking weld beads in multiple layers, comprising: a welding torch that stacks the weld beads using the consumable electrode wire; a drive unit that moves the welding torch based on a preset or calculated welding speed; a welding power source that supplies the welding current to the consumable electrode wire; and a control unit that controls the welding power source and the drive unit, wherein the weld bead includes an arc start portion that is the start position of stacking, and the control unit sets at least one of the welding current or the welding speed of the arc start portion of the layer to be currently stacked based on the number of layers or the temperature of the layer immediately preceding the layer to be currently stacked.

2. The additive manufacturing system of claim 1, wherein the control device sets the welding current of the arc start portion to be equal to or greater than the welding current of the steady portion formed after the arc start portion.

3. The additive manufacturing system of claim 1, wherein the control device sets the welding speed of the arc start portion to be equal to or lower than the welding speed of the steady portion formed after the arc start portion.

4. The additive manufacturing system according to claim 2, wherein the control device reduces the welding current of the arc start portion as the number of layers of the weld bead increases.

5. The additive manufacturing system according to claim 3, wherein the control device increases the welding speed of the arc start portion as the number of layers of the weld bead increases.

6. An additive manufacturing system according to any one of claims 1 to 5, wherein the control device changes the welding current or the welding speed of the arc start portion depending on the material of the consumable electrode wire.

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