Lamination molding system

Abstract

To enable weld beads to be stably laminated when using a consumable electrode wire.SOLUTION: A lamination molding system 1 comprises: a welding torch 20; a robot arm 40; a welding power source 10; and a control device 30. Welding beads 70 include an arc-start part which is a start position of lamination. The control device 30 sets welding currents for the arc-start part where the beads are laminated this time, on the basis of the number of laminated layers at a layer immediately preceding the layer to be laminated this time.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open Publication No. 2022-106172 (Patent Document 1) discloses that a shaped object is formed by stacking weld beads, and that the welding conditions are changed if the height of the weld bead deviates from the planned height. In Japanese Patent Application 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 stacking height. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-106172 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, a weld bead of one layer includes the arc start portion where the lamination begins, the steady portion formed after the arc start portion, and the arc end portion where the lamination ends. 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. To begin with, it is desirable not to create a difference in height between the arc start portion and the steady portion in order to stably build up the weld bead.

[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. [Means for solving the problem]

[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 the weld bead 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 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. [Effects of the Invention]

[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 deposition of a weld bead when using a consumable electrode wire. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram schematically illustrating an additive manufacturing system according to a first embodiment. [Figure 2] FIG. 2 is a diagram for explaining the relationship between the names of the various parts of a weld bead and the welding current. [Figure 3] 10 is a diagram illustrating a welding current and a shape of an arc start portion according to Comparative Example 1. FIG. [Figure 4] 10 is a diagram illustrating a welding current and a shape of an arc start portion according to Comparative Example 2. FIG. [Figure 5] 4 is a diagram illustrating a welding current and the shape of an arc start portion according to the first embodiment. FIG. [Figure 6] FIG. 4 is a diagram showing changes in welding current due to differences in materials according to the first embodiment. [Figure 7] 4 is a flowchart showing control content according to the first embodiment. [Figure 8] FIG. 10 is a diagram showing changes in welding speed according to the second embodiment. [Figure 9] FIG. 10 is a diagram schematically illustrating an additive manufacturing system according to a third embodiment. [Figure 10] FIG. 11 is a diagram showing changes in welding current due to differences in materials according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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] [Embodiment 1] 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] Robot arm 40 is a multi-joint arm, for example a six-axis multi-joint arm. Robot arm 40 functions as a drive device that moves welding torch 20 at a preset or calculated welding speed. As robot arm 40 moves welding torch 20, a weld bead 70 formed by melting consumable electrode wire 51 is deposited. Robot arm 40 is controlled by control device 30 so that a shaped object is formed by depositing 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 by a power supply tip (not shown) located inside the nozzle 21. The consumable electrode wire 51 melts due to resistance heating caused by the current and an arc generated between the consumable electrode wire 51 and the base material 80 or an already deposited weld bead 70. 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. Examples of the shielding gas that can be used include argon, CO2, and mixtures of these gases.

[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 CPU (Central Processing Unit), an MPU (Micro-Processing Unit), a TPU (Tensor Processing Unit), or a GPU (Graphics Processing Unit). 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 a consumable electrode wire 51 and builds up multiple layers of weld beads 70 to manufacture a shaped object. In the additive manufacturing system 1, a control device 30 controls the welding current output from a welding power source 10. In the additive manufacturing system 1, the control device 30 controls the welding speed by driving a 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 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 arc start portions may be stacked so that they 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 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] Figure 3 is a diagram illustrating the welding current and arc start portion according to Comparative Example 1. Figure 3(A) shows the relationship between the number of layers and the welding current, and Figure 3(B) shows the shape of the arc start portion when layering is performed with the welding current of Figure 3(A).

[0027] In Comparative Example 1, as shown in Fig. 3(A), 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, even if the number of layers increases, the initial current Is is fixed to the same value as the steady-state current Iset, so as shown in Fig. 3(B), the heat input to the arc start portion is insufficient, the wetting does not spread, and the layer height increases.

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

[0029] In Comparative Example 2, as shown in FIG. 4(A), the initial current Is is set to a value greater than the steady-state current Iset regardless of the number of layers, and a 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 in the upper layers, where heat is less easily transferred to the base metal. For this reason, in Comparative Example 2, as shown in FIG. 4(B), 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, 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 layers increases. Conversely, if Is is adjusted to the upper layers, heat input to the lower layers will be insufficient, 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 layers increases is not taken into account.

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

[0032] 5A, in the first embodiment, the welding current (initial current Is) at the arc start point is reduced as the number of layers 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 depending on the material of the consumable electrode wire 51, the time required from the arc start of the previous layer to the arc start of the next layer, etc.

[0033] Here, Is1 and Is2 can 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 current Is1 and initial current Is2, which are the welding currents for the arc start portion, are set to be equal to or greater than the steady-state current Iset, which is the welding current for the steady-state portion formed after the arc start portion, and Is1 is set to be equal to or greater than Is2. This allows the initial currents Is1 and Is2 to be appropriately set based on the steady-state current Iset.

[0034] In the first embodiment, the welding current (initial current Is) of 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) of the arc start portion of the layer to be currently laminated changes depending on the number of layers, so that when using consumable electrode wire 51, 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 consumable electrode wire 51, as the number of laminations of 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 consumable electrode wire 51, as the number of laminations of 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. Note that characteristics such as Is1, Is2, and the above-mentioned α and β, which are set for each material, are stored in 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 section depending on the thermal conductivity and other material characteristics, it is possible to stably deposit the weld bead 70 when using consumable electrode wire 51 made of various materials.

[0037] The processing executed by 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 processing of the flowchart in FIG. 7 is repeatedly called as a subroutine from the main routine in the control of control device 30 and executed. Control device 30 first checks the layering data stored in advance in 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 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 for each material from the storage device 33, 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 height of all 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 an 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] When 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. When the control device 30 determines that the stacking plan is not complete (NO in S6), it repeats the processes of S3 to S6. By 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). 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 now be described. In the second embodiment, instead of setting the welding current, the welding speed is set in the additive manufacturing system 1 of the first embodiment. FIG. 8 is a diagram showing changes in the welding speed according to the second embodiment. In FIG. 8, the welding speed set in the arc start portion is the initial welding speed vs, and the welding speed set in the steady portion is the 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 welding 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 a weld bead 70 when using a 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 an 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 an 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 allows the initial welding speeds vs1 and vs2 to be appropriately set 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 this time 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 when using consumable electrode wire 51, weld bead 70 can be stably laminated, as shown in FIG. 8.

[0047] Control device 30 may set both the welding current (initial current Is) and 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, 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 type of material used for 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 weld bead 70 when using consumable electrode wire 51 made of various materials.

[0049] [Embodiment 3] An explanation will be given of an additive manufacturing system 1A according to embodiment 3. Fig. 9 is a diagram schematically showing 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] Fig. 10 is a diagram showing changes in welding current due to differences in materials according to the third embodiment. The horizontal axis of Fig. 10 represents the temperature of the weld bead 70 of the previous layer, and the vertical axis of Fig. 10 represents the welding current (initial current Is) at the arc start portion. As shown in Fig. 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 portion, 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 portion, 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 Figure 10, the initial current varies depending on the type of material used for the consumable electrode wire 51 at the temperature of the previous layer until the initial current becomes constant. In this way, by adjusting the initial current at the arc start portion based on the thermal conductivity and other material properties, it is possible to stably deposit the weld bead 70 when using consumable electrode wire 51 made of various materials.

[0054] [Variations] Instead of the processing described in the third embodiment above, the control device 30 may set the welding speed of the layer to be currently laminated as 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) This 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 deposition 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 at the arc start portion (initial current Is) 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 beads 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 stacked, 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 beads 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. [Explanation of symbols]

[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 current, vs, vs1, vs2 initial welding speed, vset steady welding speed.

Claims

1. 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, a welding torch for depositing the weld bead using the consumable electrode wire; a drive device 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; a control device for controlling the welding power source and the drive device, the weld bead includes an arc start portion which is a lamination start position, The control device 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 before the layer to be currently stacked.

2. The additive manufacturing system according to 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 a steady portion formed after the arc start portion.

3. The additive manufacturing system according to 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 a 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 beads 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 beads increases.

6. The 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 section depending on the material of the consumable electrode wire.

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