Control Device and Control Method for an Additive Manufacturing System

Abstract

In an additive manufacturing system, based on values obtained by measuring the state of a molten pool, i.e., molten pool state measurement information, at least one of the output of a heat source, the scanning speed of the heat source, and the material supply speed of a supplied material is controlled. The control device of the additive manufacturing system includes a processing condition output unit, a heat source output addition unit, a molten pool state error calculation unit, and a speed adjustment unit. The processing condition output unit outputs values of the output of the heat source, the scanning speed of the heat source, and the material supply speed to the additive manufacturing system. The heat source output addition unit outputs, when the molten pool state error, which is the difference between the molten pool state target information and the molten pool state measurement information, is less than a specified threshold value and when the value of the output of the heat source from the processing condition output unit is less than the maximum output of the heat source, the value of the output of the heat source after addition, which adds an addition amount to the output of the heat source, to the processing condition output unit. The molten pool state error calculation unit calculates the molten pool state error based on an image. The speed adjustment unit adjusts the scanning speed of the heat source and the material supply speed based on the molten pool state error.

Description

Technical Field

[0001] The present invention relates to a control device and a control method for an additive manufacturing system that manufactures a shaped object by attaching a material to a workpiece. Background Art

[0002] As a method for manufacturing a three-dimensional processed object, additive manufacturing (AM) is known. In one mode of additive manufacturing, there is a method of irradiating a workpiece with a light beam and supplying a material to the irradiation position, thereby melting the material to perform shaping, that is, a directed energy deposition (DED) method.

[0003] The shapes of the materials supplied by the DED method are roughly classified into a wire shape and a powder shape. These materials are supplied to a molten pool formed on the workpiece side by a heat source such as light beam irradiation, thereby melting the materials. At the same time, the melted materials solidify at positions where there is no heat input by scanning the irradiation position to form a weld bead. By repeatedly forming these weld beads in the height direction, a three-dimensional shaped object is manufactured.

[0004] In the additive manufacturing process of the DED method by laser beam irradiation, as the number of stacked layers increases, the heat storage of the shaped object becomes larger. Therefore, there is a problem that, when the laser output is constant, the heat input becomes excessive in a portion with a large heat storage, resulting in deterioration of the shaping accuracy such as edge collapse or an excessive weld bead width. However, since the degree of heat storage varies depending on the type of the supplied material (i.e., the supplied material type), the type of the workpiece material (i.e., the workpiece material type), the shaping shape, and the number of stacked layers, it is difficult to set in advance to predict the heat storage and reduce the laser output. Therefore, feedback control is mostly used to sense the shape, width, etc. of the molten pool and control the heat input amount by adjusting the laser output. In addition, a method of increasing the scanning speed to reduce the heat input amount per unit distance is also known, but the molten pool has a higher responsiveness to commands than the laser output and is also easy to control. Therefore, the laser output is mostly controlled as an operation amount.

[0005] Patent Document 1 discloses the following technique: in the additive manufacturing by the laser powder DED method, the molten pool is photographed, and at least one of the output and the scanning speed of a light beam such as a laser beam is controlled based on the width or shape of the molten pool detected from the photographed image. Thereby, a high-precision three-dimensional stacked shaped object can be shaped.

[0006] The following technique is disclosed in Patent Document 2, that is, in additive manufacturing by the DED method, the heat storage temperature is extracted from the measured surface temperature data of the workpiece, and the layer stacking conditions are changed based on the printable volume calculated from the heat storage temperature. Here, the layer stacking conditions are the layer stacking height, layer stacking width, output value, supply amount, and speed.

[0007] Patent Document 1: International Publication No. 2017 / 163429

[0008] Patent Document 2: International Publication No. 2020 / 261386 Summary of the Invention

[0009] In the technique described in Patent Document 1, the width or shape of the molten pool is detected by a camera or a light sensor, and the processing conditions are feedback-controlled so that the detected data coincides with the target value. There is the following problem: as the number of stacked shaped beads increases, heat storage increases, and since the control is in the direction of reducing the heat source output, it is easy to have a surplus in the capacity of the mounted heat source output. In addition, in Patent Document 1, when the scanning speed is increased by feedback control, regarding the material supply speed, since it is constant, the material supply amount per unit area decreases. Therefore, there is also the following problem: as the scanning speed increases, the bead height decreases and the shaping accuracy deteriorates. And in the technique described in Patent Document 2, the layer stacking conditions are changed based on the heat storage temperature of the workpiece, but the layer stacking conditions are changed in such a way as to reduce the layer stacking volume in the part where the heat storage temperature is high. Therefore, there is a problem that the shaping speed decreases as the degree of heat storage increases.

[0010] The present invention has been made in view of the above circumstances, and its object is to obtain a control device for an additive manufacturing system that is less likely to have a surplus in the capacity of the heat source output and can improve the shaping accuracy and shaping speed even when the number of stacked shaped beads increases compared with the prior art.

[0011] In order to solve the above problems and achieve the object, the present invention is a control device for an additive manufacturing system, which irradiates a heat source onto a supply material supplied to a workpiece, thereby melting the supply material, solidifying the supply material to form a weld bead, and laminating the weld bead on the workpiece to manufacture a shaped object. In the additive manufacturing system, based on the value obtained by measuring the state of the molten pool formed by melting the supply material, that is, the molten pool state measurement information, at least one of the output of the heat source, the scanning speed of the heat source, and the material supply speed of the supply material is controlled. The control device of the additive manufacturing system has a processing condition output unit, a heat source output addition unit, a molten pool state error calculation unit, and a speed adjustment unit. The processing condition output unit outputs the values of the output of the heat source, the scanning speed of the heat source, and the material supply speed to the additive manufacturing system. The heat source output addition unit, when the difference between the target value of the state of the molten pool, that is, the molten pool state target information, and the molten pool state measurement information, that is, the molten pool state error, is less than a specified threshold, and when the value of the output of the heat source output from the processing condition output unit is less than the maximum output of the heat source, outputs the added heat source output value obtained by adding a specified addition amount to the output of the heat source to the processing condition output unit. The molten pool state error calculation unit calculates the molten pool state error based on the image obtained by photographing the state of the molten pool. The speed adjustment unit adjusts the scanning speed of the heat source and the material supply speed based on the molten pool state error.

[0012] Effects of the Invention

[0013] The control device for the additive manufacturing system according to the present invention has the following effects: compared with the prior art, even if the number of stacked shaped weld beads increases, it is not easy to have a surplus in the output capacity of the heat source, and the shaping accuracy and shaping speed can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram showing an example of the structure of the additive manufacturing system according to Embodiment 1.

[0015] Figure 2 It is a block diagram showing an example of the functional structure of the NC device included in the additive manufacturing system according to Embodiment 1.

[0016] Figure 3 It is a flowchart showing an example of the processing sequence of the control method for maximizing the processing speed implemented in the NC device of the additive manufacturing system according to Embodiment 1.

[0017] Figure 4 It is a diagram showing an example of the relationship between the laser output and the molten pool width in the control method of the additive manufacturing system according to Embodiment 1.

[0018] Figure 5This is a diagram showing an example of the relationship between the scanning speed and the molten pool width in the control method of the additive manufacturing system according to Embodiment 1.

[0019] Figure 6 This is a perspective view showing an example of a method for deriving the material supply speed required for shaping in the control device of the additive manufacturing system according to Embodiment 1.

[0020] Figure 7 This is a cross-sectional view showing an example of a method for deriving the material supply speed required for shaping in the control device of the additive manufacturing system according to Embodiment 1.

[0021] Figure 8 This is a perspective view schematically showing an example of the structure of a shaped object formed by an additive manufacturing system.

[0022] Figure 9 This is a diagram showing an example of the effect of increasing the shaping speed of the first layer in the control method of the additive manufacturing system according to Embodiment 1.

[0023] Figure 10 This is a diagram showing an example of the effect of increasing the shaping speed of the second layer and subsequent layers in the control method of the additive manufacturing system according to Embodiment 1.

[0024] Figure 11 This is a diagram showing an example of the behavior when the scanning speed reaches the maximum scan speed in the control method of the additive manufacturing system according to Embodiment 1.

[0025] Figure 12 This is a perspective view showing an example of a method for deriving the material supply speed required for shaping in the control device of the additive manufacturing system according to Embodiment 2.

[0026] Figure 13 This is a cross-sectional view showing an example of a method for deriving the material supply speed required for shaping in the control device of the additive manufacturing system according to Embodiment 2.

[0027] Figure 14 This is a diagram showing an example of the hardware structure of the NC device of the additive manufacturing system according to Embodiments 1 and 2. Detailed Embodiments

[0028] Hereinafter, the control device and control method of the additive manufacturing system according to the embodiments of the present invention will be described in detail based on the drawings.

[0029] Embodiment 1.

[0030] Figure 1This is a schematic diagram showing an example of the structure of the additive manufacturing system according to Embodiment 1. The additive manufacturing system 100 is a directed energy deposition (DED) type additive manufacturing system that irradiates a heat source onto a supply material 53 supplied onto a workpiece 13, thereby melting the supply material 53, solidifying the supply material 53 to form a weld bead, and manufacturing a shaped object 12 by laminating the weld beads on the workpiece 13. The types of heat sources include an arc, a laser beam L, an electron beam, etc. Here, an example of the type of heat source is the laser beam L.

[0031] The additive manufacturing system 100 includes a workbench 1, a processing head 2, a laser oscillator 3, a gas supply device 4, a material supply device 5, a scanning axis drive device 6, a camera 7, an analysis device 8, and a numerical control (NC) device 9.

[0032] The workbench 1 is a component that mounts and fixes a base material 11. The shaped object 12 is formed on the base material 11. The workpiece 13 includes the base material 11 and the shaped object 12 formed on the base material 11. The base material 11 is fixed to the workbench 1.

[0033] The processing head 2 irradiates a laser beam L onto a processing point to melt the supply material 53. The processing head 2 has: a beam nozzle 21 that irradiates the laser beam L onto the processing point; and a gas nozzle 22 that jets a shielding gas G onto the processing point. The processing point is the irradiation position of the laser beam L on the workpiece 13 and is the area where the supply material 53 is to be added. The processing point moves along a processing path during the additive processing.

[0034] The laser oscillator 3 oscillates the laser beam L as a heat source. The laser oscillator 3 is connected to the beam nozzle 21 via an optical fiber cable 31. The laser beam L oscillated from the laser oscillator 3 is transmitted in the optical fiber cable 31 and reaches the beam nozzle 21 of the processing head 2. Then, the laser beam L is emitted from the front end of the beam nozzle 21. The laser oscillator 3 is an example of a heat source generation device that generates a heat source.

[0035] The gas supply device 4 jets the shielding gas G from a gas supply source (not shown) through the gas nozzle 22 to the processing point. An example of the gas supply source is a gas cylinder. The gas supply source is connected to the gas nozzle 22 via a pipe. The gas supply device 4 can change the flow rate of the shielding gas G based on a command value from the NC device 9. The shielding gas G has the function of suppressing oxidation near the processing point and air-cooling the shaped object 12. Therefore, the shielding gas G is preferably argon or the like as an inert gas.

[0036] The material supply device 5 supplies the supply material 53 to the irradiation position of the laser beam L in the workpiece 13, that is, the processing point. The material supply device 5 includes a material supply source 51 and a material supply nozzle 52. The material supply nozzle 52 supplies the supply material 53 from the material supply source 51 to the processing point. In Embodiment 1, the supply material 53 is in the form of a wire. In Figure 1 , an example of the side supply method in which the supply material 53 is supplied from the material supply nozzle 52 disposed obliquely above the processing point is shown. The material supply device 5 may not be the side supply method, but the central supply method in which the supply material 53 is supplied from the material supply nozzle 52 disposed directly above the processing point. The material supply device 5 is operated by a servo motor (not shown) and can arbitrarily change the material supply speed of the supply material 53 based on the command value of the NC device 9.

[0037] The scanning axis drive device 6 moves the processing head 2 and the material supply device 5 in the X-axis direction, Y-axis direction, and Z-axis direction. The X-axis, Y-axis, and Z-axis are orthogonal to each other. The X-axis and Y-axis are axes parallel to the horizontal direction, and the Z-axis is a vertical axis. In addition, the positive direction of the Z-axis is set as the vertically upward direction. An example of the scanning axis drive device 6 is a servo motor (not shown) that moves the processing head 2 and the material supply device 5 in the X-axis direction, a servo motor (not shown) that moves the processing head 2 and the material supply device 5 in the Y-axis direction, and a servo motor (not shown) that moves the processing head 2 and the material supply device 5 in the Z-axis direction. By operating these servo motors, the irradiation position of the laser beam L and the supply position of the supply material 53 can be moved to arbitrary positions within the stroke range.

[0038] The camera 7 is a photographing device that photographs the area including the processing point from the positive direction of the Z-axis on the same axis as the laser beam L. In one example, the camera 7 obtains the appearance of the processing point as an image and outputs the obtained image of the processing point to the analysis device 8.

[0039] The analysis device 8 analyzes the image of the processing point input from the camera 7 and detects the width of the molten pool 14, that is, the molten pool width. The analysis device 8 outputs the detected molten pool width as the measured molten pool width to the NC device 9. Thus, the molten pool width during processing can be obtained in real time. Here, the molten pool 14 is a collection of molten metal formed by melting the workpiece 13 and the supply material 53 by the irradiation of the laser beam L. The molten pool width is an example of the molten pool state information indicating the state of the molten pool 14. The measured molten pool width corresponds to the molten pool state measurement information.

[0040] The NC device 9 controls the additive manufacturing system 100 based on a machining program and machining conditions. Here, in the machining program, movement commands for moving the machining head 2 and the material supply device 5 along a preset path and speed commands for a preset scanning axis are described. The machining conditions are a summary of the height and width of the bead to be formed and the information required for forming the height and width. The information required for forming the bead includes laser output, the scanning speed of the laser beam L, the material supply speed, and the gas flow rate. The NC device 9 controls the scanning axis drive device 6 to move the machining head 2 and the material supply device 5 along the movement path specified by the machining program. In addition, the NC device 9 designates the laser output, scanning speed, material supply speed, and gas flow rate preset by the machining conditions to the laser oscillator 3, the material supply device 5, and the gas supply device 4, respectively. The NC device 9 corresponds to a control device that controls the additive manufacturing system 100. In addition, in Embodiment 1, the NC device 9 is a control device that controls at least one of the output of the laser beam L as a heat source, the scanning speed of the laser beam L as a heat source, and the material supply speed of the supply material 53 based on the value obtained by measuring the state of the molten pool 14 formed by melting the supply material 53, that is, the molten pool state measurement information.

[0041] The NC device 9 may be one of the structural elements of the additive manufacturing system 100 or an external device.

[0042] Here, an outline of the operation of the additive manufacturing system 100 will be described. After fixing the base material 11 to the workbench 1, the NC device 9 operates the laser oscillator 3, the scanning axis drive device 6, the gas supply device 4, and the material supply device 5. That is, the NC device 9 controls the scanning axis drive device 6 based on the machining program. The scanning axis drive device 6 moves the machining head 2 and the material supply device 5 along the movement path specified by the machining program. In addition, the NC device 9 controls the laser oscillator 3, the material supply device 5, and the gas supply device 4 based on the machining conditions. As a result, the supply material 53 is supplied to the machining point, the laser beam L is irradiated from the laser oscillator 3 to the machining point via the machining head 2, and the shielding gas G is ejected to the machining point. The irradiated laser beam L forms a molten pool 14 on the workpiece 13. Moreover, the machining head 2 and the material supply device 5 move along the movement path, so that the irradiation position of the laser beam L and the material supply position move, and a bead formed by solidifying the molten supply material 53 is formed on the movement path by the molten supply material 53.

[0043] Next, the functions of the NC device 9 will be described. Figure 2 is a block diagram showing an example of the functional structure of the NC device included in the additive manufacturing system according to Embodiment 1. In Figure 2In this case, initial values of the output of the heat source, i.e., the laser output, the scanning speed, the material supply speed, and the gas flow rate, are given to the NC device 9 through the initial processing conditions 101. In addition, the target molten pool width 102 set by the user and the measured molten pool width 81 obtained by the analysis device 8 are input to the NC device 9. Here, the target molten pool width 102 is the width of the molten pool 14 that is desired to be achieved through control and can be arbitrarily set by the user. The target molten pool width 102 corresponds to the target information on the molten pool state. In the first embodiment, it is assumed that the molten pool width is equal to the width of the bead to be formed. Therefore, the value set by the target molten pool width 102 becomes the bead width that the user desires to achieve. In addition, the measured molten pool width 81 is the width of the molten pool 14 detected by the analysis device 8 from the image captured by the camera 7. The shooting by the camera 7 and the detection by the analysis device 8 are sequentially performed during processing. Therefore, the measured molten pool width 81 obtained in real time during processing is input to the NC device 9. In one example, the initial processing conditions 101 and the target molten pool width 102 are stored in a storage unit inside or outside the NC device 9.

[0044] The NC device 9 includes a molten pool width error calculation unit 91, a processing condition adjustment unit 92, a processing condition output unit 93, a laser output addition unit 94, a speed addition unit 95, a speed adjustment unit 96, and an average processing condition calculation unit 97.

[0045] The molten pool width error calculation unit 91 calculates the error between the target molten pool width 102 and the measured molten pool width 81, i.e., the molten pool width error, based on the difference between the target molten pool width 102 and the measured molten pool width 81. The molten pool width error calculation unit 91 outputs the calculated molten pool width error to the processing condition adjustment unit 92. The molten pool width error corresponds to the molten pool state error. In addition, the molten pool width error calculation unit 91 corresponds to a molten pool state error calculation unit that calculates the molten pool state error based on an image obtained by photographing the state of the molten pool 14.

[0046] The processing condition adjustment unit 92 takes the molten pool width error as an input. When the molten pool width error is greater than a specified threshold value, the processing condition adjustment unit 92 adjusts the processing conditions so that the molten pool width error is less than or equal to the set threshold value. When forming the first layer of the formed layer, i.e., the weld bead, on the substrate 11, the processing condition adjustment unit 92 outputs the initial processing condition 101 to the processing condition output unit 93. That is, the NC device 9 performs processing based on the initial processing condition 101. Then, the processing condition adjustment unit 92 determines whether the molten pool width error obtained by observing the molten pool 14 in real time is less than or equal to the threshold value. When the molten pool width error is greater than the threshold value, at least one of the laser output and the scanning speed is adjusted so that the molten pool width error is less than or equal to the set threshold value. That is, the processing condition adjustment unit 92 performs feedback control on at least one of the laser output and the scanning speed based on the molten pool width error. In addition, when changing the scanning speed, the processing condition adjustment unit 92 also adjusts the material supply speed in accordance with the scanning speed so that the height of the formed weld bead does not change. The processing condition adjustment unit 92 continues to adjust the processing conditions until the molten pool width error is less than or equal to the set threshold value.

[0047] The threshold value is a reference value for determining whether the measured molten pool width 81 and the target molten pool width 102 are within the error range, and is a value that can be arbitrarily set by the user. That is, a value that can be determined that the target molten pool width 102 and the measured molten pool width 81 are within the error range becomes the threshold value.

[0048] The processing condition output unit 93 takes as inputs the values of the laser output, the scanning speed, and the material supply speed output from the processing condition adjustment unit 92 and the laser output addition unit 94, the speed addition unit 95, and the speed adjustment unit 96 described later. The processing condition output unit 93 outputs the input values of the laser output, the scanning speed, and the material supply speed to the additive manufacturing system 100, i.e., the laser oscillator 3, the scanning axis drive device 6, and the material supply device 5. The laser oscillator 3, the scanning axis drive device 6, and the material supply device 5 operate in accordance with the command values from the processing condition output unit 93.

[0049] When the molten pool width error is greater than the threshold value, the processing conditions are input from the processing condition adjustment unit 92 to the processing condition output unit 93. When the molten pool width error is less than or equal to the threshold value, the processing conditions are input from the laser output addition unit 94, the speed addition unit 95, and the speed adjustment unit 96 to the processing condition output unit 93.

[0050] When the difference between the target molten pool width 102 and the measured molten pool width 81, i.e., the molten pool width error, is less than a specified threshold, and when the value of the laser output output from the processing condition output unit 93 is less than the maximum output of the laser oscillator 3, the laser output addition unit 94 outputs the value of the laser output after adding a specified addition amount to the laser output to the processing condition output unit 93. Specifically, the laser output addition unit 94 takes the laser output and the value of the scanning speed output from the processing condition output unit 93 as inputs. When there is a remainder of the input laser output with respect to the maximum output of the mounted laser oscillator 3 and the input scanning speed does not reach the maximum scan speed Fmax, the laser output addition unit 94 adds a specified addition amount ΔP to the laser output. The laser output addition unit 94 outputs the value of the laser output after addition to the processing condition output unit 93. The addition amount ΔP is set to a value that can be arbitrarily set by the user. The laser output addition unit 94 corresponds to the heat source output addition unit.

[0051] When the value of the scanning speed output from the processing condition output unit 93 is less than a specified value, the speed addition unit 95 outputs the scanning speed after adding the change amount ΔF of the scanning speed corresponding to the addition amount ΔP of the laser output to the scanning speed to the processing condition output unit 93. Specifically, the speed addition unit 95 takes the scanning speed and the value of the material supply speed output from the processing condition output unit 93 as inputs. When only the addition amount ΔP is added to the laser output in the laser output addition unit 94, the speed addition unit 95 adds the change amount ΔF of the scanning speed to the scanning speed F so that the molten pool width is not greater than the target molten pool width 102, based on the addition amount ΔP of the laser output. In addition, the speed addition unit 95 adds the change amount ΔW of the material supply speed to the material supply speed W based on the change amount ΔF of the scanning speed in order to keep the height of the formed bead constant. The speed addition unit 95 outputs the values of the scanning speed and the material supply speed after addition to the processing condition output unit 93.

[0052] The laser output adder 94 and the speed adder 95 change the processing conditions stepwise, so the molten pool width error may become larger than the value when feedback control is performed in the processing condition adjustment unit 92. Therefore, the speed adjustment unit 96 adjusts the scanning speed and the material supply speed based on the molten pool width error. Specifically, the speed adjustment unit 96 takes the molten pool width error as an input and adjusts the scanning speed so that the molten pool width error is less than or equal to a set threshold value. In addition, when the scanning speed is adjusted, the speed adjustment unit 96 also adjusts the material supply speed based on the adjustment amount of the scanning speed so that the height of the formed bead does not change. That is, the speed adjustment unit 96 performs feedback control on the scanning speed and the material supply speed based on the molten pool width error. The speed adjustment unit 96 outputs the adjusted values of the scanning speed and the material supply speed to the processing condition output unit 93. In addition, in this structural function, in order to preferentially maintain the laser output after being added in the laser output adder 94, the laser output is not adjusted.

[0053] The average processing condition calculation unit 97 takes as inputs the values of the laser output, the scanning speed, and the material supply speed output from the processing condition output unit 93, and calculates the respective averages for the same forming layer. That is, the average processing condition calculation unit 97 calculates the values of the average heat source output, i.e., the average laser output, the average scanning speed, and the average material supply speed, during bead formation for the same forming layer.

[0054] In addition, the processing condition adjustment unit 92 operates the additive manufacturing system 100 using the initial values, i.e., the initial processing conditions 101, which are predetermined as the laser output, the scanning speed, and the material supply speed at the start of forming for the first forming layer formed by bead formation, and performs feedback control on at least one of the laser output, the scanning speed, and the material supply speed. In addition, when the forming layer is switched, the processing condition adjustment unit 92 operates the additive manufacturing system 100 using the values of the average laser output, the average scanning speed, and the average material supply speed of the immediately preceding forming layer as the values of the laser output, the scanning speed, and the material supply speed at the start of forming for the switched forming layer, and performs feedback control on at least one of the laser output, the scanning speed of the heat source, and the material supply speed. At this time, the processing condition adjustment unit 92 uses the values of the average laser output, the average scanning speed, and the average material supply speed calculated by the average processing condition calculation unit 97.

[0055] Next, the internal processing of the NC device 9 will be described. Figure 3It is a flowchart showing an example of the processing sequence of a control method for maximizing the processing speed to be implemented in the NC device of the additive manufacturing system according to Embodiment 1. First, the initial processing conditions 101 and the target molten pool width 102 are input to the processing condition adjustment unit 92 (step S11). The initial processing conditions 101 include the values of the laser output, the scanning speed, and the material supply speed. Next, based on the initial processing conditions 101, the processing is started (step S12). Here, the processing condition adjustment unit 92 outputs the initial processing conditions 101 to the processing condition output unit 93. The processing condition output unit 93 outputs the initial value of the laser output to the laser oscillator 3, the initial value of the scanning speed to the scanning axis drive device 6, and the initial value of the material supply speed to the material supply device 5.

[0056] If the processing starts, the camera 7 captures an image of the processing position, that is, an image representing the state of the molten pool 14, and outputs the image to the analysis device 8. The analysis device 8 detects the measured molten pool width 81 from the image and inputs the measured molten pool width 81 to the molten pool width error calculation unit 91. Then, the molten pool width error calculation unit 91 calculates the difference between the measured molten pool width 81 from the analysis device 8 and the target molten pool width 102, that is, the molten pool width error (step S13). The molten pool width error calculation unit 91 determines whether the molten pool width error is less than or equal to a specified threshold value (step S14).

[0057] When the molten pool width error is not less than or equal to the threshold value (when the result of step S14 is No), the processing condition adjustment unit 92 obtains the molten pool width error from the molten pool width error calculation unit 91, and accordingly adjusts at least one of the values of the laser output, the scanning speed, and the material supply speed (step S15). As an adjustment method used here, in one example, feedback control such as PID (Proportional-Integral-Differential) control is implemented. Here, when the processing condition adjustment unit 92 adjusts the scanning speed, it also adjusts the material supply amount corresponding to the change amount of the scanning speed so that the bead height formed as described above does not change.

[0058] In one example, if the molten pool width error is positive, since the molten pool width during processing is smaller than the target molten pool width 102, the processing condition adjustment unit 92 issues an instruction to increase the laser output or decrease the scanning speed. On the other hand, if the molten pool width error is negative, since the molten pool width during processing is larger than the target molten pool width 102, the processing condition adjustment unit 92 issues an instruction to decrease the laser output or increase the scanning speed.

[0059] Then, the processing condition adjustment unit 92 outputs at least one of the adjusted laser output, scanning speed, and material supply speed to the processing condition output unit 93. The processing condition output unit 93 reflects the processing conditions including the adjusted values among the values of the laser output, scanning speed, and material supply speed (step S16). When the laser output is adjusted, the processing condition output unit 93 outputs the adjusted value of the laser output to the laser oscillator 3. When the scanning speed is adjusted, the processing condition output unit 93 outputs the adjusted value of the scanning speed to the scanning axis driving device 6 and outputs the adjusted material supply speed to the material supply device 5. At least one of the laser oscillator 3, the scanning axis driving device 6, and the material supply device 5 operates according to the input command value, so that the width of the molten pool during processing changes to be consistent with the target molten pool width 102.

[0060] Then, it is determined whether the processing of the same shaping layer is completed (step S22). In one example, the determination is made by the processing condition adjustment unit 92. When the processing of the same shaping layer is not completed (when the result of step S22 is No), the process returns to step S13. Moreover, until the molten pool width error is less than or equal to the threshold value, the processes shown in steps S15 and S16 performed by the processing condition adjustment unit 92 are repeatedly executed. That is, until the width of the molten pool during processing is consistent with the target molten pool width 102, only the adjustment implemented by feedback control in the processing condition adjustment unit 92 is performed.

[0061] On the other hand, when the molten pool width error is less than or equal to the threshold value in step S14 (when the result of step S14 is Yes), it means that the width of the molten pool during processing after being changed by the processes in steps S15 and S16 is consistent with the target molten pool width 102 within the error range. In this case, the laser output addition unit 94 obtains the laser output and the value of the scanning speed from the processing condition output unit 93, and determines whether the adjusted laser output is less than the maximum output Pmax of the mounted oscillator and whether the scanning speed is less than the maximum scan speed Fmax. In Figure 3 this example, the laser output addition unit 94 determines whether the laser output P is less than the maximum output Pmax of the mounted oscillator according to the obtained value of the laser output (step S17). Then, the laser output addition unit 94 determines whether the scanning speed F is less than the maximum scan speed Fmax that can be achieved by the scanning axis driving device 6, that is, the maximum scan speed (step S18). The determination in step S17 is made from the perspective of the hardware of the mounted laser oscillator 3, and the determination in step S18 is made from the perspective of processing stability.

[0062] Here, the maximum output Pmax of the mounted oscillator refers to the maximum value that can be output in terms of the hardware specifications in the laser oscillator 3 used for processing when mounted on the additive manufacturing system 100. Additionally, the maximum scan speed Fmax refers to the upper limit of the scan speed that ensures control stability. In one example, the scan speed is experimentally changed in advance for processing, and the maximum scan speed Fmax is obtained based on the processing results and an index indicating control stability.

[0063] When the adjusted laser output P is less than the maximum output Pmax of the mounted oscillator (when Yes in step S17) and the scan speed F is less than the maximum scan speed Fmax (when Yes in step S18), it is determined that the laser output can be increased. That is, the laser output adder 94 adds a prescribed addition amount ΔP to the laser output P (step S19), and outputs the laser output P after adding the addition amount ΔP to the processing condition output unit 93. Moreover, the processing condition output unit 93 designates the value of the added laser output to the laser oscillator 3.

[0064] In step S19, if only the value of the laser output is added, the molten pool width expands and will exceed the target molten pool width 102. Therefore, when the laser output is added in step S19, the speed adder 95 adds the scan speed change amount ΔF to the scan speed F. Additionally, by adding the scan speed change amount ΔF to the scan speed F, the heat input amount per unit distance decreases and the molten pool width shrinks. The speed adder 95 adds the material supply speed change amount ΔW to the material supply speed W corresponding to the scan speed change amount ΔF in order to keep the bead height constant (step S20).

[0065] In steps S19 and S20, the processing conditions, namely the laser output, scan speed, and material supply speed, are changed stepwise. Therefore, it is possible that the measured molten pool width 81 does not match the target molten pool width 102. Thus, the speed adjustment unit 96 adjusts the scan speed and material supply speed corresponding to the molten pool width error obtained from the molten pool width error calculation unit 91 (step S21). That is, the speed adjustment unit 96 performs feedback control on the scan speed and material supply speed corresponding to the molten pool width error. In one example, the scan speed F is adjusted using the scan speed adjustment amount ΔFfb that performs feedback control on the scan speed corresponding to the molten pool width error, and the material supply speed W is adjusted using the material supply speed adjustment amount ΔWfb that performs feedback control on the material supply speed corresponding to the molten pool width error. As a result, the generated molten pool width error decreases. In addition, regarding the laser output, in order to maintain the commanded value after addition in step S19, no adjustment is made in the process of step S21.

[0066] Then, the processing condition adjustment unit 92 determines whether the processing in the same shaping layer has ended (step S22). When the processing in the same shaping layer has not ended (when the result in step S22 is No), the processing of the same layer continues, so the process returns to step S13. That is, when the molten pool width error is less than or equal to the threshold, adjustment is performed through the processing from step S17 to step S21, and processing is executed with the values of the added laser output, scanning speed, and material supply speed, then returns to step S13, and the adjustment of the processing conditions is implemented again from step S13.

[0067] When the laser output P is greater than or equal to the maximum output Pmax of the mounted oscillator in step S17 (when the result in step S17 is No), or when the scanning speed F is greater than or equal to the maximum scan speed Fmax in step S18 (when the result in step S18 is No), it is determined that the laser output cannot be increased, and the process proceeds to step S22.

[0068] When it is determined in step S22 that the processing of the same shaping layer has ended (when the result in step S22 is Yes), the processing condition adjustment unit 92 determines whether the shaping has ended (step S23). When it is determined that the shaping has not ended (when the result in step S23 is No), it is the timing to switch the shaping layer. If the shaping layer is switched, the shaping position and heat storage state change. Therefore, it is not preferable to continuously use the processing conditions adjusted through the processing from step S15 to step S21 or the added processing conditions in the shaping layer just before the switch in the processing of the switched shaping layer. In addition, if the initial processing conditions 101 are used, the shaping may be unstable at the beginning of the processing due to the difference in the heat storage state.

[0069] Therefore, in Embodiment 1, the average processing condition calculation unit 97 calculates the average values of the processing conditions used in the shaping layer just before the switch, that is, the average laser output, average scanning speed, and average material supply speed of the shaping layer just before the switch (step S24). Then, based on the values of the average laser output, average scanning speed, and average material supply speed, which are the average values of the processing conditions used in the shaping layer just before the switch, the processing of the next shaping layer is started (step S25). The average laser output, average scanning speed, and average material supply speed are processing conditions that reflect the heat storage state of the shaping layer just before the switch. Therefore, compared with the case of using the initial processing conditions 101, the stability at the beginning of the processing is improved. Then, the process jumps to step S13. In addition, when it is determined that the shaping has ended (when the result in step S23 is Yes), the processing condition output unit 93 ends the process.

[0070] Next, a method for calculating the change amount ΔW of the material supply speed corresponding to the change amount ΔF of the scanning speed in the speed addition unit 95 will be described. Figure 4 FIG. is an example showing the relationship between the laser output and the molten pool width in the control method of the additive manufacturing system according to Embodiment 1. Figure 5 FIG. is an example showing the relationships between the scanning speed and the molten pool width in the control method of the additive manufacturing system according to Embodiment 1. In Figure 4 in the upper graph G11, the horizontal axis represents the position and the vertical axis represents the laser output. In the lower graph G12, the horizontal axis represents the position and the vertical axis represents the molten pool width. In Figure 4 , the upper graph G11 and the lower graph G12 are displayed with their positions aligned. In Figure 5 in the upper graph G21, the horizontal axis represents the position and the vertical axis represents the scanning speed. In the lower graph G22, the horizontal axis represents the position and the vertical axis represents the molten pool width. In Figure 5 , the upper graph G21 and the lower graph G22 are displayed with their positions aligned. The position on the horizontal axis in these graphs is, in one example, the position on the movement path.

[0071] In Figure 4 , the change amount ΔM of the molten pool width when the laser output is increased by a prescribed addition amount ΔP is set. If the change amount ΔM of the molten pool width is regarded as a function in which the addition amount ΔP of the laser output is a variable, it can be expressed by the following formula (1). The relationship between the change amount ΔM of the molten pool width and the addition amount ΔP of the laser output needs to be derived in advance.

[0072] ΔM = f(ΔP) · · · (1)

[0073] In addition, in Figure 5 , the change amount ΔF of the scanning speed for reducing the molten pool width by ΔM is set. If the change amount ΔF of the scanning speed is regarded as a function in which the change amount ΔM of the molten pool width is a variable, it can be expressed by the following formula (2). The relationship between the change amount ΔF of the scanning speed and the change amount ΔM of the molten pool width needs to be derived in advance.

[0074] ΔF = g(ΔM) · · · (2)

[0075] As shown in formula (1) and formula (2) to the following formula (3), when the laser output is changed by the addition amount ΔP, the change amount ΔF of the scanning speed that should be changed to maintain the molten pool width can be derived.

[0076] ΔF = g(f(ΔP)) · · · (3)

[0077] That is, the change amount ΔF of the scanning speed when the laser output changes by an additive amount ΔP can be obtained according to Equation (3).

[0078] However, there are a shooting and analysis time until the measurement of the molten pool width 81 is calculated, and a response delay in the change of the molten pool width with respect to the scanning speed. Therefore, if the scanning speed exceeds a specified value, the above cannot be ignored and the adjustment cannot be correctly performed. The limit scanning speed at which the correct adjustment can be made is called the maximum scan speed Fmax. The maximum scan speed Fmax is set by the user in consideration of the sampling period of the camera 7, the analysis time in the analysis device 8, the command value output period of the NC device 9, and the response delay of the molten pool width with respect to the scanning speed.

[0079] When the scanning speed exceeds the maximum scan speed Fmax, the addition of the laser output in the laser output addition unit 94 and the addition of the scanning speed and the material supply speed in the speed addition unit 95 are not performed. That is, the adjustment of the scanning speed and the material supply speed in the speed adjustment unit 96 is not performed.

[0080] Figure 6 It is a perspective view showing an example of a method for deriving the material supply speed required for shaping in the control device of the additive manufacturing system according to Embodiment 1. Figure 7 It is a cross-sectional view showing an example of a method for deriving the material supply speed required for shaping in the control device of the additive manufacturing system according to Embodiment 1. As Figure 6 and Figure 7 shown, when the supply material 53 is in a wire shape, all of the supply material 53 is melted and the bead 15 is properly formed. Therefore, the volume of the bead 15 formed per unit time is equal to the volume of the supply material 53 supplied per unit time. Here, the material supply speed W, the scanning speed F, and the bead cross-sectional area S have the relationship shown in the following Equation (4).

[0081] W = F × S ··· (4)

[0082] Here, as Figure 7 shown, the ratio of the bead cross-sectional area S to the area of the quadrilateral formed by the width of the bead 15, i.e., the bead width M, and the height of the bead 15, i.e., the bead height H, in the cross-section of the bead 15 is defined as the bead cross-section coefficient K. The bead cross-section coefficient K is a coefficient for considering the geometric shape of the bead 15 and is a value that can be arbitrarily set by the user. The bead cross-sectional area S is expressed by the following Equation (5) using the bead width M, the bead height H, and the bead cross-section coefficient K.

[0083] S = M × H × K ··· (5)

[0084] Accordingly, Equation (4) can be expressed as Equation (6) below using the bead width M, bead height H, and bead profile coefficient K.

[0085] W = F × (M × H × K) ··· (6)

[0086] As described above, the change amount ΔW of the material supply speed W when the scanning speed F changes by ΔF can be calculated according to Equation (7) below. However, the bead height H is set to the target shaping height H that can be arbitrarily set by the user. target . Additionally, if the molten pool width is the same as the bead width, the bead width M can use the measured molten pool width M obtained in real time during processing. measure . That is, the speed adder 95 can use the measured molten pool width M. measure , the target shaping height H target , the change amount ΔF of the scanning speed, and the geometric shape of the bead 15 to calculate the change amount ΔW of the material supply speed.

[0087] ΔW = ΔF × (Mmeasure × Htarget × K) ··· (7)

[0088] Figure 8 is a perspective view schematically showing an example of the structure of a shaped object shaped by an additive manufacturing system. Here, a state is shown in which a shaped object 12 composed of 6 layers of beads 15 is formed on a substrate 11.

[0089] Figure 9 is a diagram showing an example of the effect of increasing the shaping speed of the first layer in the control method of the additive manufacturing system according to Embodiment 1. In Figure 9 in the upper graph G31, the horizontal axis represents position and the vertical axis represents the measured molten pool width. In the middle graph G32, the horizontal axis represents position and the vertical axis represents the laser output. In the lower graph G33, the horizontal axis represents position, the left vertical axis represents the scanning speed, and the right vertical axis represents the material supply speed. In Figure 9 , the upper graph G31, the middle graph G32, and the lower graph G33 are displayed with their positions aligned. In addition, the position on the horizontal axis in these graphs is, in one example, the position on the movement path.

[0090] Regarding the first layer, that is, Figure 8 the first layer bead 15a on the substrate 11 of Figure 9As shown, processing is started with the values of the initial laser output, the initial material supply speed, and the initial scanning speed determined as the initial processing condition 101. The processing condition adjustment unit 92 adjusts the laser output so that the measured molten pool width 81 matches the target molten pool width 102. That is, between the positions from S0 to S1, while keeping the scanning speed and the material supply speed constant, the measured molten pool width 81 is made to match the target molten pool width 102 by only decreasing the laser output.

[0091] If the measured molten pool width 81 and the target molten pool width 102 match at the position S1, then at the position S1, according to the graph G32, the laser output P is less than the maximum output Pmax of the mounted oscillator, and according to the graph G33, the scanning speed F is less than the maximum scan speed Fmax. Therefore, the laser output addition unit 94 adds the addition amount ΔP to the laser output P. At the same time, the scanning speed F and the material supply speed W are also respectively added with the change amounts ΔF, ΔW. After the addition, the measured molten pool width 81 changes from the target molten pool width 102, generating a molten pool width error. Therefore, by adjusting the scanning speed F and the material supply speed W, the molten pool width error is controlled within the threshold. Therefore, after the measured molten pool width 81 and the target molten pool width 102 match, during the period from when the addition amount ΔP is added to the laser output P until the next addition amount ΔP is added, the laser output P is a constant value in the graph G32. In contrast, in the graph G33, the scanning speed F and the material supply speed W are not constant values and increase slowly.

[0092] Then, by repeatedly adding the addition amount ΔP to the above laser output P, the laser output P is increased until it reaches the maximum output Pmax of the mounted oscillator. While adding the addition amount ΔP to the laser output P, the change amount ΔF is added to the scanning speed F, and the change amount ΔW is added to the material supply speed W. Moreover, after the laser output P reaches the maximum output Pmax of the mounted oscillator at the position S2, the processing condition adjustment unit 92 continues the adjustment implemented by the feedback control of the processing conditions.

[0093] As described above, by increasing the laser output P until it reaches the maximum output of the mounted oscillator, the material supply speed W can be increased, and as a result, the shaping speed can be increased.

[0094] Figure 10 It is a diagram showing an example of the effect of increasing the shaping speed in the second layer and subsequent layers in the control method of the additive manufacturing system according to Embodiment 1. In Figure 10In the upper graph G41, the horizontal axis represents the position and the vertical axis represents the measured molten pool width. In the middle graph G42, the horizontal axis represents the position and the vertical axis represents the laser output. In the lower graph G43, the horizontal axis represents the position, the left vertical axis represents the scanning speed, and the right vertical axis represents the material supply speed. In Figure 10 the upper graph G41, the middle graph G42, and the lower graph G43 are displayed with their positions aligned. In addition, the position on the horizontal axis in these graphs is, in one example, the position on the movement path.

[0095] In the second layer and subsequent layers, in one example, regarding Figure 8 the bead 15b of the fifth layer of Figure 9 the values of the laser output, scanning speed, and material supply speed at the start of shaping are respectively the average laser output, average scanning speed, and average material supply speed values of the previous shaping layer. Shaping starts with processing conditions that reflect the heat storage state, so the time until the measured molten pool width 81 matches the target molten pool width 102 is shorter than in the case of

[0096] Figure 11 FIG. is an example showing the behavior when the scanning speed reaches the maximum scan speed in the control method of the additive manufacturing system according to Embodiment 1. In Figure 11 the upper graph G51, the horizontal axis represents the position and the vertical axis represents the measured molten pool width. In the middle graph G52, the horizontal axis represents the position and the vertical axis represents the laser output. In the lower graph G53, the horizontal axis represents the position, the left vertical axis represents the scanning speed, and the right vertical axis represents the material supply speed. In Figure 11 the upper graph G51, the middle graph G52, and the lower graph G53 are displayed with their positions aligned. In addition, the position on the horizontal axis in these graphs is, in one example, the position on the movement path.

[0097] As Figure 11 shown, when the scanning speed F reaches the maximum scan speed Fmax before the laser output P reaches the maximum output Pmax of the mounted oscillator, the laser output P is not added, so the laser output P does not reach the maximum output Pmax of the mounted oscillator. That is, depending on the set value of the maximum scan speed Fmax or the heat storage state, the laser output P may not reach the maximum output Pmax of the mounted oscillator. Considering this, the maximum output Pmax of the mounted oscillator cannot be used from the start of processing, and as described above, it is necessary to gradually increase the laser output P.

[0098] According to Embodiment 1, until the target molten pool width 102 and the measured molten pool width 81 are the same, at least one of the laser output, the scanning speed, and the material supply speed is feedback-controlled until the molten pool width error disappears. Further, after the target molten pool width 102 and the measured molten pool width 81 are the same, when the scanning speed has not reached the maximum scan speed Fmax, the laser output during processing is increased to the maximum output Pmax of the mounted oscillator, and at the same time, the scanning speed and the material supply speed are increased. At this time, the scanning speed and the material supply speed are adjusted by feedback control according to the molten pool width error. Thus, the capacity of the laser output as a heat source is not likely to have a surplus, and the desired bead height is maintained unchanged, and the maximum formable speed can be achieved by the output of the mounted oscillator. That is, the decrease in the bead height associated with the increase in the scanning speed is suppressed, the forming accuracy is not impaired, and the forming speed can be increased. In particular, in the upper part of the stacked beads with a large heat storage, in the prior art, the laser output is reduced or the scanning speed is increased, thereby suppressing the heat input per unit area. However, in Embodiment 1, the scanning speed and the material supply speed are increased without reducing the laser output. Therefore, when compared with the prior art, the forming accuracy and the forming speed can also be improved in the upper part of the formed object 12 having a larger heat storage than the non-heat storage part.

[0099] Further, when the forming layer is switched to the next layer, in the start condition of the processing of the switched forming layer, the average laser output, the average scanning speed, and the average material supply speed of the previous forming layer are used as the processing conditions. Thus, compared with the case where the processing of each forming layer is started with the preset initial processing conditions 101, the processing stability of each forming layer is improved, and therefore the forming accuracy can be improved.

[0100] Embodiment 2.

[0101] Figure 1 The illustrated material supply device 5 supplies the supply material 53 from the material supply nozzle 52. In Embodiment 1, an example in which the supply material 53 is in the form of a wire is given, but in Embodiment 2, a case in which the supply material 53 is in the form of powder is exemplified.

[0102] The basic structure of the additive manufacturing system 100 of Embodiment 2 is the same as that of Embodiment 1. Hereinafter, the differences from Embodiment 1 will be described. As described above, in Embodiment 2, the powder-shaped supply material 53 is supplied from the material supply nozzle 52. Even when the shape of the supply material 53 changes from a wire shape to a powder shape, the same effect can be obtained if the method for deriving the material supply speed required for forming in the speed adder 95 is changed.

[0103] Figure 12It is a perspective view showing an example of a method for deriving the material supply speed required for shaping in the control device of the additive manufacturing system according to Embodiment 2. Figure 13 It is a cross-sectional view showing an example of a method for deriving the material supply speed required for shaping in the control device of the additive manufacturing system according to Embodiment 2. In addition, in Figure 12 it is exemplified that the material supply nozzle 52 of the material supply device 5 is provided on the processing head 2.

[0104] When the supply material 53 is in powder form, during the supply, the supply material 53 also scatters outside the molten pool 14, so not all of the supply material 53 contributes to shaping. Let the supply speed of the supply material 53a that contributes to shaping be W melt The supply speed W of the supply material 53a that contributes to shaping melt is proportional to the material supply speed W. If this ratio is set as the shaping contribution rate A, then the supply material 53a that actually contributes to shaping can be expressed by the following formula (8). The shaping contribution rate A is set as a value that can be arbitrarily set by the user according to the device structure, etc.

[0105] W melt = W × A ··· (8)

[0106] That is, by replacing the material supply speed W in Embodiment 1 with the supply speed W melt of the supply material 53a that contributes to shaping, the change amount ΔW of the material supply speed W in Embodiment 2 can be calculated as follows in formula (9).

[0107] ΔW = ΔF × (M measure × H target × K) / A ··· (9)

[0108] Using formula (9) and considering the supply material 53x that does not contribute to shaping to calculate the change amount ΔW of the material supply speed W, thus, in Embodiment 2, the same effect as in Embodiment 1 can also be obtained.

[0109] In addition, in the above description, first, the laser outputs are added in the laser output adder 94, and then the scanning speed and the material supply speed are added in the speed adder 95. However, the order of this addition can also be swapped. That is, steps S19 and S20 can be swapped. Figure 3 Swap steps S19 and S20.

[0110] In addition, in the speed adjustment unit 96 and the processing condition adjustment unit 92 of Embodiments 1 and 2, the processing conditions are adjusted using the molten pool width error as an input. However, instead of using the molten pool width, the difference between the area or shape of the molten pool 14 and the target value may be used as an input to adjust the processing conditions. That is, the state of the molten pool is the area or shape of the molten pool 14, and the difference between the target value of the state of the molten pool, i.e., the molten pool state target information, and the measured value of the state of the molten pool, i.e., the molten pool state measurement information, may be used as an input to adjust the processing conditions.

[0111] Here, the hardware structure of the NC device 9 of the additive manufacturing system 100 will be described. Figure 14 FIG. is an example of the hardware structure of the NC device of the additive manufacturing system according to Embodiments 1 and 2.

[0112] The NC device 9 can be implemented by Figure 14 the control circuit 300 shown, i.e., the processor 301 and the memory 302. Examples of the processor 301 are a CPU (also referred to as a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). Examples of the memory 302 are a RAM (Random Access Memory) or a ROM (Read Only Memory).

[0113] In Figure 2 the case where some or all of the functions of the molten pool width error calculation unit 91, the processing condition adjustment unit 92, the processing condition output unit 93, the laser output addition unit 94, the speed addition unit 95, the speed adjustment unit 96, and the average processing condition calculation unit 97 are implemented by the processor 301, some or all of these functions are implemented by the processor 301 in combination with software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 302. The processor 301 reads and executes the program stored in the memory 302, thereby implementing some or all of the functions of the molten pool width error calculation unit 91, the processing condition adjustment unit 92, the processing condition output unit 93, the laser output addition unit 94, the speed addition unit 95, the speed adjustment unit 96, and the average processing condition calculation unit 97.

[0114] In the case where part or all of the functions of the molten pool width error calculation unit 91, the processing condition adjustment unit 92, the processing condition output unit 93, the laser output addition unit 94, the speed addition unit 95, the speed adjustment unit 96, and the average processing condition calculation unit 97 are implemented by the processor 301, the NC device 9 stores in the memory 302 a program that finally executes the steps performed by part or all of the molten pool width error calculation unit 91, the processing condition adjustment unit 92, the processing condition output unit 93, the laser output addition unit 94, the speed addition unit 95, the speed adjustment unit 96, and the average processing condition calculation unit 97. The program stored in the memory 302 can be said to cause the computer to execute the order or method performed by part or all of the molten pool width error calculation unit 91, the processing condition adjustment unit 92, the processing condition output unit 93, the laser output addition unit 94, the speed addition unit 95, the speed adjustment unit 96, and the average processing condition calculation unit 97.

[0115] A control program describing a control method of the additive manufacturing system 100 executed by the processor 301 can be provided as a computer program product by being stored in a computer-readable storage medium in the form of an installable file or an executable file. In addition, the control program executed by the processor 301 can also be provided to the NC device 9 of the additive manufacturing system 100 via a network such as the Internet.

[0116] In addition, the NC device 9 can also be implemented by dedicated hardware. In addition, regarding the functions of the NC device 9, part can be implemented by dedicated hardware and part can be implemented by software or firmware.

[0117] The structure shown in the above embodiment represents an example, and it can also be combined with other known technologies, and embodiments can also be combined with each other. Without departing from the gist, part of the structure can also be omitted or changed.

[0118] Explanation of reference numerals

[0119] 1 Workbench, 2 Processing head, 3 Laser oscillator, 4 Gas supply device, 5 Material supply device, 6 Scanning axis drive device, 7 Camera, 8 Analysis device, 9 NC device, 11 Substrate, 12 Shaped object, 13 Workpiece, 14 Molten pool, 15, 15a, 15b Weld beads, 21 Beam nozzle, 22 Gas nozzle, 31 Optical cable, 51 Material supply source, 52 Material supply nozzle, 53 Supply material, 53a Supply material contributing to shaping, 53x Supply material not contributing to shaping, 91 Molten pool width error calculation unit, 92 Processing condition adjustment unit, 93 Processing condition output unit, 94 Laser output addition unit, 95 Speed addition unit, 96 Speed adjustment unit, 97 Average processing condition calculation unit, 100 Additive manufacturing system, G Protection gas, L Laser beam.

Claims

1. A control device for an additive manufacturing system, in an additive manufacturing system that manufactures a shaped object by irradiating a heat source onto a supply material supplied to a workpiece to melt the supply material, and then solidifying the supply material to form a bead, and laminating the beads on the workpiece, controls at least one of the output of the heat source, the scanning speed of the heat source, and the material supply speed of the supply material based on the value obtained by measuring the state of the molten pool formed by melting the supply material, i.e., the molten pool state measurement information. The control device for the additive manufacturing system is characterized by having: A processing condition output unit that outputs the values of the output of the heat source, the scanning speed of the heat source, and the material supply speed to the additive manufacturing system; A molten pool state error calculation unit that calculates a molten pool state error, which is the difference between the target value of the state of the molten pool, i.e., the molten pool state target information, and the molten pool state measurement information, based on an image obtained by photographing the state of the molten pool. A processing condition adjustment unit that adjusts at least one of the value of the output of the heat source, the scanning speed, and the value of the material supply speed in accordance with the value of the molten pool state error when the molten pool state error is not less than or equal to a specified threshold. A heat source output addition unit that, when the molten pool state error is less than the threshold, adds a specified addition amount to the output of the heat source when the value of the output of the heat source output from the processing condition output unit is less than the maximum output of the heat source and the scanning speed is low compared to the maximum scanning speed achievable by the scanning axis drive device that scans the heat source, and increases the value of the output of the heat source until it reaches the maximum output and outputs it to the processing condition output unit. A speed addition unit that, when the heat source output addition unit adds the specified addition amount to the output of the heat source, outputs the added scanning speed obtained by adding the change amount of the scanning speed corresponding to the addition amount of the output of the heat source to the scanning speed to the processing condition output unit, and outputs the added material supply speed obtained by adding the change amount of the material supply speed corresponding to the change amount of the scanning speed to the material supply speed to the processing condition output unit. And A speed adjustment unit that adjusts the scanning speed of the heat source and the material supply speed based on the molten pool state error.

2. The control device for the additive manufacturing system according to claim 1, wherein The speed addition unit calculates the change amount of the scanning speed using the relationship between the output of the heat source and the state of the molten pool obtained in advance and the relationship between the scanning speed and the state of the molten pool obtained in advance.

3. The control device for the additive manufacturing system according to claim 1, wherein The speed addition unit calculates the change amount of the material supply speed by using the molten pool state measurement information, the scanning speed, and the geometric shape of the bead.

4. The control device of the additive manufacturing system according to any one of claims 1 to 3, characterized in that The processing condition adjustment unit operates the additive manufacturing system by using initial values pre-determined as the output of the heat source, the scanning speed of the heat source, and the material supply speed at the start of shaping of the first layer formed by the bead, and adjusts at least one of the output of the heat source, the scanning speed of the heat source, and the material supply speed. When switching the shaping layer, the processing condition adjustment unit operates the additive manufacturing system by using the values of the average heat source output, the average scanning speed, and the average material supply speed of the shaping layer immediately before switching as the values of the output of the heat source, the scanning speed of the heat source, and the material supply speed at the start of shaping of the switched shaping layer, and adjusts at least one of the output of the heat source, the scanning speed of the heat source, and the material supply speed.

5. The control device of the additive manufacturing system according to claim 4, characterized in that It further has an average processing condition calculation unit that calculates the values of the average heat source output, the average scanning speed, and the average material supply speed when forming the bead of the same shaping layer.

6. A control method of an additive manufacturing system, which is an additive manufacturing system that manufactures a shaped object by irradiating a supply material supplied onto a workpiece with a heat source to melt the supply material and then solidifying the supply material to form a bead and laminating the bead on the workpiece. Based on the value obtained by measuring the state of the molten pool formed by melting the supply material, i.e., the molten pool state measurement information, the control method of the additive manufacturing system implemented by a control unit that controls at least one of the output of the heat source, the scanning speed of the heat source, and the material supply speed of the supply material. The control method of the additive manufacturing system is characterized by including the following steps: A processing condition output step in which the control unit outputs the values of the output of the heat source, the scanning speed of the heat source, and the material supply speed to the additive manufacturing system; A molten pool state error calculation step in which the control unit calculates a molten pool state error, which is the difference between the molten pool state target information, which is the target value of the state of the molten pool, and the molten pool state measurement information, based on an image obtained by photographing the state of the molten pool. A processing condition adjustment step in which, when the molten pool state error is not less than or equal to a specified threshold value, at least one of the value of the output of the heat source, the scanning speed, and the value of the material supply speed is adjusted according to the value of the molten pool state error. Heat source output addition process: When the molten pool state error is less than the threshold value, if the output value of the heat source output from the control unit is less than the maximum output of the heat source and the scanning speed is low compared to the maximum scanning speed achievable by the scanning axis drive device that scans the heat source, a specified addition amount is added to the output of the heat source, and the output value of the heat source is increased until it reaches the maximum output; Speed addition process: When the specified addition amount is added to the output of the heat source, a change amount of the scanning speed corresponding to the addition amount of the output of the heat source is added to the scanning speed, and a change amount of the material supply speed corresponding to the change amount of the scanning speed is added to the material supply speed; and Speed adjustment process: The control unit adjusts the scanning speed of the heat source and the material supply speed based on the molten pool state error, Until the output of the heat source becomes the maximum output of the heat source, the process from the processing condition output process to the speed adjustment process is repeatedly executed.

7. The control method of the additive manufacturing system according to claim 6, characterized in that In the speed addition process, the change amount of the scanning speed is calculated using the relationship between the output of the heat source and the state of the molten pool obtained in advance, and the relationship between the scanning speed and the state of the molten pool obtained in advance.

8. The control method of the additive manufacturing system according to claim 6, characterized in that In the speed addition process, the change amount of the material supply speed is calculated using the molten pool state measurement information, the scanning speed, and the geometric shape of the weld bead.

9. The control method of the additive manufacturing system according to any one of claims 6 to 8, characterized in that The processing condition adjustment process uses the initial values determined in advance as the output of the heat source, the scanning speed of the heat source, and the material supply speed at the start of the formation of the first layer of the formed layer formed by the weld bead, to operate the additive manufacturing system, and adjusts at least one of the output of the heat source, the scanning speed of the heat source, and the material supply speed. In the processing condition adjustment process, when the formed layer is switched, as the values of the output of the heat source, the scanning speed of the heat source, and the material supply speed at the start of the formation of the switched formed layer, the values of the average heat source output, the average scanning speed, and the average material supply speed of the formed layer just before the switch are used to operate the additive manufacturing system, and at least one of the output of the heat source, the scanning speed of the heat source, and the material supply speed is adjusted.

10. The control method of the additive manufacturing system according to claim 9, characterized in that It further includes an average processing condition calculation process, that is, calculates the values of the average heat source output, the average scanning speed, and the average material supply speed when the weld bead of the same formed layer is formed.

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