Molding condition setting device, additive manufacturing system, molding condition setting method, and program

Abstract

Provided is a technique for additive manufacturing by appropriately controlling an angle of a torch according to a shape of a molding object while maintaining an ideal distance between the torch and the molding object. A molding condition setting device sets a molding condition when performing additive manufacturing of a molding object by a WAAM method. The molding condition setting device comprises: a means for determining whether a difference between a measured value of a distance between a torch and a molding object and a design value of the distance is within an allowable range; and a means for correcting a target welding position included in the molding condition so that the difference becomes within the allowable range when the difference exceeds the allowable range, and correcting the torch angle so as to coincide with the molding direction on the basis of the shape of the molding object at the corrected target welding position.

Description

Modeling condition setting device, additive manufacturing system, modeling condition setting method, and program

[0001] This disclosure claims priority to Japanese Patent Application No. 2024-023283, filed on February 19, 2024, the contents of which are incorporated herein by reference.

[0002] A wire arc additive manufacturing (WAAM) method (wire-arc additive manufacturing) is available, which builds a desired shape by layering weld beads made by melting and solidifying a filler metal. To create a high-precision object, the width and height of the weld bead must be controlled. However, in actual manufacturing, the desired shape of the weld bead may not be achieved. For example, if the temperature of the object rises excessively during manufacturing, the weld bead flattens, widening the width and reducing the height, as shown in Figure 8A. Especially when the number of layers is large, height errors have an integral effect. Therefore, even slight differences per layer become significant as the number of layers increases. In addition to changes in shape, this can lead to changes in the distance between the torch and the object, resulting in unstable manufacturing or even contact between the torch and the object. To address this issue, Patent Document 1 discloses a method for measuring the shape of an existing weld bead using a sensor attached to a torch, adjusting welding conditions such as the amount of filler metal supplied, welding speed, heat input, and weaving conditions to reduce the difference between the measured and planned weld bead heights, and then performing subsequent additive manufacturing. However, changing the welding conditions can change the build width. This can result in, for example, a thin-walled object in which each layer is built in a single pass (one welding), resulting in an object with a thickness different from the planned object, which is undesirable.

[0003] If the shape of the weld bead becomes flattened due to an excessive temperature rise during printing, even if the difference per layer is small, as the number of layers increases, the integral of that difference changes the distance between the torch and the object. This difference cannot be ignored, and the distance between the torch and the object increases. Figure 8B shows the relationship between the distance between the torch and the object and the quality of the object. Diagram 81 on the left side of Figure 8B shows the ideal distance between the torch and the object. Diagram 82 in the middle of Figure 8B shows the state where the torch and the object are farther apart. This can result in defects and an unstable arc. Diagram 83 on the right side of Figure 8B shows the state where the torch and the object are closer. This can result in interference between the object and the torch and unstable printing. If the weld bead becomes flat, the torch and the object will be farther apart, which can lead to unstable welding. For objects where the build angle changes, if the shape of the weld bead becomes flat, errors in the build height per layer accumulate during multilayer buildup. Furthermore, the angle change corresponding to the arc length is not reflected, resulting in a shape that is completely different from the planned build. An example of such buildup is shown in Figure 8C . Line 84 in Figure 8C indicates the trajectory of the build (the path of the torch tip movement) set to reflect the shape of the object to be built, and line 85 indicates the shape of the actual buildup. In this example, the build height error per layer accumulates due to the effects of flattening and changes in the distance between the torch and the object, and the resulting inability to appropriately change the torch angle, resulting in a shape that differs from the target. To perform additive manufacturing without changing the shape of the object, it is necessary to maintain the ideal distance between the torch and the object while simultaneously changing the torch angle according to the desired shape, without changing welding conditions that would change the build width.

[0004] Japanese Patent No. 6912636

[0005] To provide a technology for layered manufacturing that appropriately controls the torch angle according to the shape of the object while maintaining an ideal distance between the torch and the object.

[0006] The present disclosure provides a modeling condition setting device, an additive manufacturing system, a modeling condition setting method, and a program that can solve the above-mentioned problems.

[0007] According to one aspect of the present disclosure, a manufacturing condition setting device is a manufacturing condition setting device that sets manufacturing conditions when additively manufacturing an object to be manufactured using the WAAM method, and has a means for determining whether the difference between the measured value of the distance between the torch and the object to be manufactured and the design value of the distance is within an acceptable range, and if the difference exceeds the acceptable range, a means for correcting a target welding position included in the manufacturing conditions so that the difference is within the acceptable range, and a means for correcting a torch angle so that it matches the manufacturing direction based on the shape of the object to be manufactured at the corrected target welding position.

[0008] According to one aspect of the present disclosure, an additive manufacturing system is an additive manufacturing system that additively manufactures an object to be manufactured using the WAAM method, and includes a welding system having a torch and a sensor that measures the distance to an object fixed in a fixed positional relationship with the torch, a control device that controls the welding system, and the above-mentioned manufacturing condition setting device.

[0009] According to one aspect of the present disclosure, the manufacturing condition setting method is a manufacturing condition setting method executed by a computer for setting manufacturing conditions when additively manufacturing an object to be manufactured using the WAAM method, and includes the steps of: determining whether a difference between a measured value of the distance between a torch and an object to be manufactured and a design value of the distance is within an acceptable range; and, if the difference exceeds the acceptable range, correcting a target welding position included in the manufacturing conditions so that the difference is within the acceptable range, and correcting a torch angle so that it matches the manufacturing direction based on the shape of the object to be manufactured at the corrected target welding position.

[0010] According to one aspect of the present disclosure, the program causes a computer to execute a process for setting manufacturing conditions when additively manufacturing an object to be manufactured using the WAAM method, the process including the steps of determining whether the difference between the measured value of the distance between the torch and the object to be manufactured is within an acceptable range and, if the difference exceeds the acceptable range, correcting the target welding position included in the manufacturing conditions so that the difference falls within the acceptable range, and correcting the torch angle so that it matches the manufacturing direction based on the shape of the object to be manufactured at the corrected target welding position.

[0011] The above-described manufacturing condition setting device, additive manufacturing system, manufacturing condition setting method, and program enable additive manufacturing while maintaining an ideal distance between the torch and the object to be manufactured, and controlling the torch angle to an appropriate angle according to the shape of the object.

[0012] FIG. 1 is a block diagram showing an example of an additive manufacturing system according to an embodiment; FIG. 2 is a diagram showing the positional relationship between a torch and a sensor, and a model, according to an embodiment; FIG. 3 is a first diagram illustrating a distance measurement method according to an embodiment; FIG. 4 is a second diagram illustrating a distance measurement method according to an embodiment; FIG. 5 is a first diagram illustrating a method for correcting a modeling path according to an embodiment; FIG. 6 is a second diagram illustrating a method for correcting a modeling path according to an embodiment; FIG. 7 is a flowchart showing an example of a modeling condition setting process according to an embodiment; FIG. 8 is a first diagram illustrating an example of a problem that occurs during additive manufacturing; FIG. 9 is a second diagram illustrating an example of a problem that occurs during additive manufacturing; FIG. 10 is a diagram showing an example of a problem that occurs during additive manufacturing; FIG. 11 is a diagram illustrating an example of a hardware configuration of a control device according to an embodiment;

[0013] <Embodiment> A method for detecting and correcting a building path in WAAM-based additive manufacturing according to the present disclosure will be described below with reference to the drawings. (Configuration) FIG. 1 is a block diagram showing an example of an additive manufacturing system according to an embodiment. The additive manufacturing system 100 includes a welding system 1 and a control device 10. The welding system 1 includes a welding robot 2, a welding machine 3, a wire feeder 4, a torch 5, a sensor 8, a cooling device 9, and the like. A sensor 8 is fixed to the torch 5 for non-contact measurement of the distance between the torch 5 and a built object 6. The sensor 8 is, for example, a laser rangefinder, but is not limited thereto. For example, the sensor 8 may be a sensor that measures distance using ultrasound or an image. The sensor 8 is fixed at a position where it measures the distance between the sensor 8 and the built object 6 at a position preceding the building position by the torch 5. The cooling device 9 is a device that sprays water or air onto the built object. The cooling device 9 is used to forcibly cool the built object 6 when the temperature of the built object rises excessively. The welding system 1 performs WAAM-type additive manufacturing based on instructions from the control device 10, and forms a molded object 6 on the positioning device 7. The welding system 1 performs the manufacturing using short-circuit transfer MIG welding. Short-circuit transfer MIG welding is characterized by low heat input (low molten pool temperature) and high viscosity of the weld bead. By using short-circuit transfer MIG welding, deformation of the weld bead due to gravity can be ignored even when the torch 5 is oriented not only vertically downward but also diagonally or sideways (horizontally), and a desired shape can be formed in the same way as when the torch 5 is oriented downward. The control device 10 includes a shape data acquisition unit 11, a distance detection unit 12, a manufacturing condition setting unit 13, a control unit 14, and a memory unit 15.

[0014] The shape data acquisition unit 11 acquires shape data of the object to be formed. The shape data is, for example, a three-dimensional model (CAD data) that represents the shape of the object to be formed. The width and size of the object to be formed at any position can be calculated from the shape data. The distance detection unit 12 detects the distance between the tip of the torch 5 and the surface of the object 6 to be formed. Specifically, the distance detection unit 12 acquires the value measured by the sensor 8 and detects the distance from the tip of the torch 5 to the object 6 to be formed based on this value.

[0015] The printing condition setting unit 13 sets various printing conditions required for printing the object 6. For example, the printing condition setting unit 13 initially sets a printing path for each layer of the object 6. The printing path includes a printing center position and a torch angle that represent the target welding position for each layer. The printing condition setting unit 13 sets various welding conditions such as a welding speed, voltage, current, wire supply amount, and torch angle. For example, the printing condition setting unit 13 sets the torch angle in a direction that matches the printing direction of the object corresponding to the position of the torch 5. When printing actually starts, the printing condition setting unit 13 corrects the printing path. For example, the printing condition setting unit 13 calculates the difference between the initially set printing center position and the actual position where printing is performed based on the distance detected by the distance detection unit 12, and corrects the printing center position so that the distance detected by the distance detection unit 12 becomes a predetermined distance. After correcting the printing center position, the printing condition setting unit 13 corrects the torch angle in a direction along the shape of the object 6 at the corrected printing center position (tangential direction of the object 6). If the printing condition setting unit 13 determines that there is a possibility that the temperature of the object 6 has excessively increased, based on the magnitude of the difference between the distance detected by the distance detection unit 12 and the ideal distance, it determines that the printing condition for the object 6 is to cool the object 6.

[0016] The control unit 14 controls the welding system 1 based on the building path and welding conditions set by the building condition setting unit 13, and performs WAAM-type additive manufacturing using short-circuit transfer MIG welding. For example, the control unit 14 performs building based on the building path corrected by the building condition setting unit 13 by adjusting the position and angle of the torch 5 so that the distance between the torch 5 and the object 6 does not become too close or too far and falls within a predetermined tolerance range, and the torch angle does not deviate from the tangent direction of the shape of the object at the building position. When the weld bead is flattened due to an excessive temperature rise of the object 6, for example, the control unit 14 operates the cooler 9 to cool the object 6 and suppress changes in the shape of the object 6. The memory unit 15 stores the shape data acquired by the shape data acquisition unit 11, the building path and welding conditions set by the building condition setting unit 13, a database (described below) used to calculate the welding conditions, and the like.

[0017] Next, a method for detecting the distance between the torch 5 and the object 6 will be described with reference to FIG. 2 . As shown in FIG. 2 , the sensor 8 is fixed at a position in the traveling direction of the torch 5 where the distance between the reference surface 8 a of the sensor 8 and the reference surface 5 a of the torch 5 is a predetermined value Df. The sensor 8 measures the distance Lb to the object 6. The position of the object 6 to be measured is the surface of the layer one layer below the layer currently being formed. Then, the distance Rf between the torch 5 and the object 6 can be calculated by Rf = Lb - Df. The distance detection unit 12 may detect the distance Rf between the torch 5 and the object 6 by subtracting Df from the value Lb measured by the sensor 8, or may treat the measured value Lb as the distance between the torch 5 and the object 6. In this embodiment, from the viewpoint of maintaining a constant distance between the welding object and the torch 5 in order to stabilize the quality of welding, the sensor 8 is provided ahead of (leading) the torch 5 in the direction of travel so that the distance to the welding object can be measured, but the position is not limited to the example shown in Fig. 2. For example, the sensor 8 may be provided on the opposite side of the direction of travel of the torch 5, and the distance between the torch 5 and the object 6 may be detected by adding, for example, an estimated value of the thickness of the layer currently being formed to the value measured by the sensor 8.

[0018] A schematic diagram of the cross section of the object 6 is shown in Figure 3. When the torch 5 is facing downward, as shown in Printing Example 31, the distance between the sensor 8 and the apex 61 of the bead of the object 6 is measured vertically. When short-circuit transfer MIG welding is used, the bead can be layered in the direction of the torch angle. Therefore, when the object 6 is inclined (Printing Example 32) or has a shape that extends horizontally (Printing Example 33), the torch 5 is tilted at the same angle as the inclination of the object 6 (when the object is horizontal, the torch 5 is laid horizontally). Even in these cases, the sensor 8 is tilted in the same way as the torch 5, so the distance between the bead apex 61 and the sensor 8 can be measured regardless of the orientation of the torch 5.

[0019] When an arc-shaped path is being formed as shown in FIG. 4 , the position of the sensor 8 measuring the distance to the preceding position may be misaligned horizontally with the position of the torch 5. As a result, the value measured by the sensor 8 may not necessarily be the distance to the object 6. In such a case, for example, the peak height value (the value at which the distance between the sensor 8 and the object 6 is shortest) among the values ​​measured by the sensor 8 is adopted as the distance Lb (when the sensor 8 measures the distance at each position within the range indicated by the arrow 8b). Even when the forming path is a straight line, some fluctuations may occur. Therefore, a dead zone may be set for the values ​​measured by the sensor 8 so that some fluctuations can be ignored. Regardless of the shape of the forming path, the average or median value of the values ​​measured by the sensor 8 over a predetermined period of time (in the case of the arc-shaped path described above, the average value of the adopted peak values, etc.) may be adopted as the distance Lb. In the case where the modeling path is a circumference, when modeling of the Nth layer starts, goes around the circle, and approaches the original modeling start position, the sensor 8 suddenly changes from measuring the distance to the modeling surface of the (N-1)th layer to measuring the distance to the Nth layer after modeling. If the distance changes suddenly in this way by more than a certain amount, the movement speed of the torch 5 may be controlled to decelerate and the torch position may be controlled to gradually rise while gently advancing in a slope. This enables stable modeling.

[0020] Next, a method for correcting a printing path will be described with reference to FIG. 5 . Printing example 51 in FIG. 5 is a printing example in which beads are stacked vertically. Each arc in Printing Example 51 represents the bead shape of the Nth layer, with the first to fifth layers illustrated from the bottom. P1 is the printing center position of the first layer, and P2 to P5 are the printing center positions of the second to fifth layers, respectively. The printing condition setting unit 13 initializes the printing path before actual printing. For example, the positions of P1 to P5 in FIG. 5 are designed. The torch angle at P1 to P5 is designed to match the printing direction, i.e., downward. The control unit 14 moves the torch 5 in accordance with the designed printing path to perform additive printing. Here, a method for initially setting the printing path will be described, focusing on the height positions of P1 to P5. The printing condition setting unit 13 refers to the shape data of the object to be printed in Printing Example 51 and identifies the portion of the object to be printed that corresponds to the first layer. The building condition setting unit 13 calculates the width of the specified portion from the shape data, and sets this value as the building width of the first layer. Next, the building condition setting unit 13 references a database that defines the correspondence between building widths and welding conditions, and sets the welding conditions for the first layer. Next, the building condition setting unit 13 references a database that defines the correspondence between building heights and welding conditions, and calculates the building height of the first layer when building is performed under the welding conditions that correspond to the building width of the first layer. The building condition setting unit 13 sets the calculated building height as the height-direction position of P1. Once the building height of the first layer has been calculated, the building condition setting unit 13 references the shape data, specifies the width of the object to be built at the portion that corresponds to the building height of the first layer, and sets this value as the building width of the second layer. Then, the building condition setting unit 13 calculates the welding conditions and the building height of the second layer in the same procedure as for the first layer, and sets the value obtained by adding the building height of the first layer to the building height of the second layer as the height-direction position of P2. If the build width of each layer remains constant, the build height of each layer will also be constant. By repeating the same process, the build center positions P3 to P5 of each layer can be set. The build condition setting unit 13 calculates the inclination angle of the object 6 at the build center positions P3 to P5 by referring to the shape data, and sets the torch angle so that the inclination of the torch 5 matches the calculated inclination angle and the tip of the torch 5 faces the lower layer in the build direction. In this example, the torch angle is set vertically downward.The control unit 14 moves the torch 5 to a position where the thus set P1 to P5 corresponds to the center position of the weld (the bead top 61 in Figure 3), and controls the torch angle at each position to match the torch angle set by the weld condition setting unit 13, thereby performing short-circuit transfer MIG welding.

[0021] Here, the vertical movement amount of the torch 5 per layer is Ds, the actual build height per layer is Da, and the fluctuation error ΔD = Ds - Da. If the first layer can be built as planned, ΔD = 0, and the distance Lb measured by the sensor 8 will be constant. Here, assume that due to bead flattening, the actual build height Da of the first layer becomes smaller than the planned value Ds. Then, if the torch 5 is moved (raised) as planned to build the second layer, the distance between the torch 5 and the object 6 will be greater by ΔD than the ideal predetermined distance Ls. If the distance between the torch 5 and the object 6 increases, there is a possibility that the build will become unstable depending on the size of ΔD. Therefore, for example, when the printing condition setting unit 13 detects that the distance Lb measured by the sensor 8 after the start of printing of the second layer is longer than the distance Ls (for example, Ls is the ideal distance between the torch 5 and the object 6) by ΔD, the printing condition setting unit 13 corrects the value of the printing center position P2 of the second layer downward by ΔD. Accordingly, the printing condition setting unit 13 also corrects the height directions of P3 to P5 of the third and subsequent layers to lower positions. A correction example 52 in FIG. 5 illustrates this process. P2' to P5' are the corrected printing center positions. When the value of the printing center position P2 of the second layer is corrected downward by ΔD, the control unit 14 corrects the position of the torch 5 downward accordingly. As a result, the distance Lb between the torch 5 and the object 6 can be made closer to the distance Ls. For example, the printing condition setting unit 13 calculates the difference ΔL between the distance Lb and the distance Ls (ΔL = Lb - Ls). If ΔL > L1 (the sensor 8 is far from the object 6), the printing condition setting unit 13 corrects the printing center positions P2' to P5' of each layer toward the lower layer along the printing direction. If ΔL < -L1 (the sensor 8 is close to the object 6), the printing condition setting unit 13 corrects the printing center positions P2' to P5' of each layer toward the upper layer along the printing direction. The range -L1 ≦ ΔL ≦ L1 is a dead zone. After the printing center positions P2' to P5' are corrected, the control unit 14 controls the position of the torch 5 based on the corrected printing center positions P2' to P5'. This allows the distance between the object 6 and the torch 5 to be within the allowable range, preventing contact between the torch 5 and the object 6 and instability in printing due to poor shielding. In this example, since the modeling direction is vertical, there is no need to correct the torch angle even if the modeling center position is corrected to P2' to P5'.

[0022] Flattening the beads not only reduces the build height, but also increases the build width. Strictly speaking, this means that the build width also increases compared to the planned value. Although this has a smaller impact than the accumulation of build height errors due to stacking, the change in build width can be suppressed as follows:

[0023] If the actual build height Da is lower than the build height Ds per layer, the object 6 may be flattened. Flattening the object 6 may increase the width of the object 6, potentially making it impossible to obtain the desired shape. Therefore, a tolerance is set, and the temperature of the object 6 is controlled when the build height falls below a certain value (when ΔL exceeds the tolerance). Possible temperature control methods include (1) temporarily stopping the build and cooling the object; (2) cooling the object with water or air; and (3) reducing the wire supply rate during build to reduce heat input. However, considering the build speed, method (2) is more efficient. Cooling with water, air, or carbon dioxide may be used. For example, when ΔL exceeds the tolerance, the control unit 14 operates the cooler 9 to cool the object 6. This reduces width changes and defects due to overheating.

[0024] Next, correction of the printing path for a model 6 having a shape with a variable angle will be described with reference to FIG. 6 . To print a model 6 with a variable angle, the printing path (trajectory) must not only be non-linear, but the angle of the torch 5 must also be varied. The printing condition setting unit 13 calculates the printing width for each layer based on the shape data of the object to be printed, and sets the welding conditions for each layer by referring to a database that defines the correspondence between the printing width and the welding conditions. The printing height for each layer is set by referring to a database that defines the correspondence between the printing height and the welding conditions. These processes are the same as those for printing in the vertical direction. However, when setting the printing width, the orientation of the object to be printed is taken into consideration. For example, if the object to be printed is inclined, the width of the object to be printed in a direction perpendicular to the inclination is used as the printing width. The printing center position of the next layer is also calculated by adding the printing height of each layer to the upper layer along the orientation of the object to be printed (along the printing direction). The printing center positions P1 to P5 in the printing example 61 in FIG. 6 are examples of initial settings of printing paths set in this manner. The printing condition setting unit 13 initially sets the torch angle according to the printing direction at the printing center positions P1 to P5. For example, for the printing center position P1, the torch angle is initially set to the direction that coincides with the printing direction (tangential direction) at P1 (the direction of the arrow 621 in the planned value in the correction example 62). Similarly, for P2 and P3, the torch angles are initially set to the directions of the arrows 622 and 623, respectively. The control unit 14 moves the torch 5 based on the printing center positions P1 to P5 to perform printing welding. When measuring the distance Lb, the sensor 8 is inclined at the same angle as the torch 5, so it can measure the distance between the torch 5 and the object 6 in the same way as in the case of vertical printing. If the distance Lb to the object 6 deviates from the distance Ls, the printing center position is corrected according to the difference. Since the torch angle is adjusted to face the same direction as the printing direction of the object 6 during printing, when the printing center position is corrected, it is necessary to change the torch angle as well as the position of the torch 5. The control unit 14 moves the torch 5 based on the corrected printing center position, and adjusts the angle of the torch 5 based on the shape of the object 6 at the corrected printing center position. An example of the processing for correcting the printing center position when the object 6 has a shape whose angle changes will be described below.Assume that, after the initial setting of the modeling path, modeling of the first layer is performed, and as a result, the modeling center position of the first layer is shifted downward by ΔL along the shape of the modeled object 6, as shown in Modification Example 62. In this case, for example, the modeling condition setting unit 13 calculates a straight line connecting the modeling center position P1 of the first layer to the modeling center position P2 of the second layer, and calculates the position of point P2' obtained by moving the modeling center position P2 toward the modeling center position P1 by ΔL along this straight line. Similarly, the modeling condition setting unit 13 calculates a straight line connecting the modeling center position P2 of the second layer to the modeling center position P3 of the third layer, and calculates the position of point P3' obtained by moving the modeling center position P3 toward the modeling center position P2 by ΔL along this straight line. The calculated P2' and P3' are the corrected modeling center positions. The printing condition setting unit 13 calculates the inclination angle of the object 6 at the corrected printing center position P2', and corrects the torch angle so that the inclination of the torch 5 matches the calculated inclination angle and the tip of the torch 5 faces the lower layer in the printing direction. Similarly, the printing condition setting unit 13 corrects the torch angle at P3' based on the corrected printing center position P3'. The control unit 14 corrects the position of the torch 5 and the angle of the torch 5 based on the corrected printing center position P2' and the corrected torch angle at P2', and prints the second layer. After printing of the second layer is completed and the printing of the third layer begins, the printing condition setting unit 13 calculates the printing height of the second layer based on the measurement results of the sensor 8, and corrects the printing center positions P3' to P5' and the torch angle at each position as necessary. If the object cannot be printed with the initially planned number of layers due to flattening of the beads, for example, the number of layers is increased. When printing an inclined object 6, if the set printing height differs from the actual printing height, the printing path is likely to deviate, resulting in an unintended shape. A significant deviation in the positional relationship between the torch 5 and the object 6 causes an arc to be generated in an unintended direction, resulting in an unanticipated shape being printed. According to this embodiment, the correction process described above corrects the position of the torch 5 in accordance with the tip position of the object 6 during printing, and adjusts the angle of the torch 5 to match the desired shape, thereby enabling the intended shape to be printed.

[0025] (Operation) Next, the flow of the printing path correction process according to this embodiment will be described with reference to FIG. 7 . FIG. 7 is a flowchart showing an example of the printing condition setting process according to this embodiment. The shape data acquisition unit 11 acquires shape data of the object to be printed (Step S10). For example, the shape data is shape data of a thin-walled structure configured with one pass. Next, the printing condition setting unit 13 performs initial setting of the printing path (Step S11). For example, the printing condition setting unit 13 sets the variable N to 1 and calculates the printing width of the Nth layer. For example, if N = 1, the printing condition setting unit 13 calculates the width of the bottom surface of the object to be printed as the printing width. If N > 1, the printing condition setting unit 13 calculates the sum of the printing heights up to the (N-1)th layer, and calculates the width of the object to be printed at a position corresponding to the calculated value in the shape data as the printing width. Next, the printing condition setting unit 13 calculates the welding conditions (e.g., welding speed, current, voltage, wire feed rate, etc.) for the Nth layer based on the calculated printing width, by referring to a database that defines the correspondence between the printing width and the welding speed. The building condition setting unit 13 calculates the inclination angle of the object to be built at a position corresponding to the Nth layer by referring to the shape data, and sets a torch angle such that the torch 5 is tilted by the calculated angle. The inclination angle of the object to be built can be determined, for example, by calculating the angle between a line connecting the center positions of the object at each height and a horizontal plane. The building condition setting unit 13 calculates the building height of the Nth layer by referring to a database that defines the correspondence between the building height and the welding conditions, calculates the position obtained by moving the object upward by the building height along the shape of the object from the (N-1)th layer to the Nth layer, and sets the calculated position as the building center position of the Nth layer. The building condition setting unit 13 calculates initial settings for the building pass (building center position, torch angle, etc.) for each layer while adding 1 to N until the top edge of the object to be built is reached.

[0026] Next, the control unit 14 starts the fabrication based on the initial setting of the fabrication path (Step S12). Fabrication is performed sequentially from the first layer. Hereinafter, the layer to be fabricated will be referred to as the Nth layer. The welding system 1 fabricates the Nth layer while measuring the distance Lb using the sensor 8 (Step S13). The measurement value of the sensor 8 is transmitted to the control device 10 each time. The distance detection unit 12 detects the distance Rf between the torch 5 and the fabricated object 6 based on the distance Lb measured by the sensor 8. Alternatively, the distance Lb may be treated as the distance Rf. The fabrication condition setting unit 13 calculates the difference ΔL between the distance Rf (or distance Lb) detected by the distance detection unit 12 and the target distance Ls (Step S14). If ΔL is greater than a predetermined threshold Th2 (Step S15; Large), the fabrication condition setting unit 13 instructs the control unit 14 to temporarily suspend fabrication. The control unit 14 temporarily stops the modeling (step S16), and when the time required for the modeled object 6 to cool has elapsed, repeats the process from step S13.

[0027] If ΔL is smaller than a predetermined threshold value Th2 and larger than a predetermined threshold value Th1 (step S15; middle), the modeling condition setting unit 13 instructs the control unit 14 to cool the model 6. Here, threshold value Th2 is greater than threshold value Th1. The control unit 14 operates the cooler 9 to cool the model 6 (step S17). When the time required for cooling the model 6 has elapsed, the control unit 14 stops the cooler 9. In this case, the process proceeds to step S18.

[0028] If ΔL is smaller than the threshold value Th1 (step S15; small), the printing condition setting unit 13 corrects the printing path in accordance with the magnitude of ΔL (step S18). For example, if ΔL = 0, the printing condition setting unit 13 does not correct the printing path. If ΔL > L1 or ΔL < -L1, the printing condition setting unit 13 corrects the printing path (printing center position, torch angle). The correction method is as described with reference to FIGS. 5 and 6.

[0029] The control unit 14 continues modeling until the Nth layer is completed, while performing various processes according to the magnitude of ΔL. When the modeling of the Nth layer is completed, the modeling condition setting unit 13 determines whether the modeling is completed (Step S19). If the modeling height of each layer from the first layer to the Nth layer is stacked along the shape of the object, and the Nth layer reaches the end of the object opposite to the modeling start side, the modeling condition setting unit 13 determines that the modeling is completed. If not, the modeling condition setting unit 13 determines that the modeling is incomplete. If it is determined that the modeling is completed (Step S19; Yes), the process of FIG. 7 is completed. If it is determined that the modeling is incomplete (Step S19; No), the modeling condition setting unit 13 starts modeling of the next layer (N+1th layer) (Step S20). The process from Step S13 is repeated for the N+1th layer.

[0030] (Effects) As described above, according to this embodiment, additive manufacturing can be performed while maintaining the distance between the torch 5 and the object 6 within a certain range. Additive manufacturing can be performed while controlling the torch angle according to the shape of the object 6 at the manufacturing position. This not only stabilizes the manufacturing process for each layer, but also makes it possible to manufacture an object that accurately reproduces the shape of the object to be manufactured.

[0031] 9 is a diagram showing an example of the hardware configuration of the control device 10 according to the embodiment. The computer 900 includes a CPU 901, a main storage device 902, an auxiliary storage device 903, an input / output interface 904, and a communication interface 905. The above-described control device 10 is implemented in the computer 900. The above-described functions are stored in the auxiliary storage device 903 in the form of a program. The CPU 901 reads the program from the auxiliary storage device 903, loads it into the main storage device 902, and executes the above-described processing in accordance with the program. The CPU 901 allocates a storage area in the main storage device 902 in accordance with the program. The CPU 901 allocates a storage area in the auxiliary storage device 903 for storing data being processed in accordance with the program.

[0032] A program for implementing all or part of the functions of the control device 10 may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed to perform processing by each functional unit. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. If a WWW system is used, the term "computer system" also includes the homepage provision environment (or display environment). The term "computer-readable recording medium" refers to portable media such as CDs, DVDs, and USBs, as well as storage devices such as hard disks built into the computer system. If the program is distributed to the computer 900 via a communication line, the computer 900 may load the program into the main storage device 902 and execute the processing described above. The program may be for implementing part of the functions described above, or may be capable of implementing the functions described above in combination with a program already stored in the computer system.

[0033] As described above, several embodiments according to the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as defined in the claims, as well as in the scope and spirit of the invention.

[0034] <Additional Notes> The modeling condition setting device, the layered modeling system, the modeling condition setting method, and the program described in the embodiments can be understood, for example, as follows.

[0035] (1) A first aspect of the manufacturing condition setting device is a manufacturing condition setting device that sets manufacturing conditions for additive manufacturing of an object by the WAAM method, and includes: a means for determining whether a difference between a measured value of the distance between a torch and an object to be manufactured falls within an allowable range; and, if the difference exceeds the allowable range, a means for correcting a target welding position included in the manufacturing conditions so that the difference falls within the allowable range, and a means for correcting a torch angle so that the torch angle coincides with the manufacturing direction based on the shape of the object to be manufactured at the corrected target welding position. This allows additive manufacturing to be performed while maintaining the distance between the torch 5 and the object 6 within a certain range. By controlling the torch angle in accordance with the shape of the object to be manufactured, an object that accurately reproduces the shape of the object to be manufactured can be manufactured.

[0036] (2) A second aspect of the present invention relates to the molding condition setting device of (1), further comprising: a unit for setting, when the difference exceeds the allowable range and the difference has a magnitude that indicates an excessive temperature rise of the object, that the molding condition be to cool the object. This makes it possible to suppress a change in width of the object due to flattening of beads caused by an excessive temperature rise.

[0037] (3) A third aspect of the manufacturing condition setting device is the manufacturing condition setting device according to (1) or (2), wherein, in the case where the object to be manufactured has a shape that is to be manufactured by stacking layers in a vertical direction, the correcting means corrects the target welding position upward by a value corresponding to the difference if the difference indicates that the torch and the object are closer than the allowable range, and corrects the target welding position downward by a value corresponding to the difference if the difference indicates that the torch and the object are farther apart than the allowable range. This enables additive manufacturing to be performed while maintaining the distance between the torch 5 and the object 6 within a certain range.

[0038] (4) A fourth aspect of the manufacturing condition setting device is the manufacturing condition setting device of any one of (1) to (3), wherein, when the object to be manufactured has an inclined shape, if the difference indicates that the torch and the object are closer than the tolerance range, the correcting means corrects the target welding position upward along the inclined direction by a value corresponding to the difference, and corrects the torch angle so that the target welding position coincides with the manufacturing direction indicated by the shape of the object to be manufactured at the corrected target welding position and the tip of the torch faces the direction of the lower layer in the manufacturing process; and if the difference indicates that the torch and the object are farther apart than the tolerance range, the correcting means corrects the target welding position downward along the inclined direction by a value corresponding to the difference, and corrects the torch angle so that the target welding position coincides with the manufacturing direction indicated by the shape of the object to be manufactured at the corrected target welding position and the tip of the torch faces the direction of the lower layer in the manufacturing process. This allows additive manufacturing to be performed while maintaining the distance between the torch 5 and the object 6 within a certain range.

[0039] (5) A fifth aspect of the present invention provides the model-forming condition setting device according to (2), wherein, if the difference is equal to or smaller than a predetermined first threshold, the means for setting cooling determines to cool the model by spraying water or gas onto the model. This allows the model to be cooled.

[0040] (6) A sixth aspect of the present invention provides the modeling condition setting device according to (2) or (5), wherein, if the difference is equal to or greater than a predetermined second threshold value that is greater than the first threshold value, the means for setting cooling determines to temporarily suspend modeling. This allows the model to cool.

[0041] (7) The seventh aspect of the additive manufacturing system is an additive manufacturing system that additively manufactures an object to be manufactured using the WAAM method, and includes a welding system having a torch and a sensor that measures the distance to an object fixed in a fixed positional relationship with the torch, a control device that controls the welding system, and a manufacturing condition setting device described in (1) to (6).

[0042] (8) The eighth aspect of the additive manufacturing system is an additive manufacturing system that additively manufactures an object to be manufactured using the WAAM method, and includes a welding system having a torch, a sensor that measures the distance to a fixed object in a fixed positional relationship with the torch, and a cooler that cools the object; a control device that controls the welding system; and a manufacturing condition setting device described in (2), (5) to (6).

[0043] (9) A ninth aspect of the manufacturing condition setting method is a manufacturing condition setting method executed by a computer for setting manufacturing conditions when additive manufacturing an object to be manufactured using the WAAM method, and includes the steps of: determining whether the difference between the measured value of the distance between the torch and the object to be manufactured and the design value of the distance is within an acceptable range; and, if the difference exceeds the acceptable range, correcting the target welding position included in the manufacturing conditions so that the difference is within the acceptable range, and correcting the torch angle so that it matches the manufacturing direction based on the shape of the object to be manufactured at the corrected target welding position.

[0044] (10) A program according to the tenth aspect causes a computer to execute a process for setting manufacturing conditions when additively manufacturing an object to be manufactured using the WAAM method, the process including the steps of: determining whether the difference between the measured value of the distance between the torch and the object to be manufactured is within an acceptable range; and, if the difference exceeds the acceptable range, correcting the target welding position included in the manufacturing conditions so that the difference falls within the acceptable range; and correcting the torch angle so that it matches the manufacturing direction based on the shape of the object to be manufactured at the corrected target welding position.

[0045] The present disclosure provides a modeling condition setting device, an additive manufacturing system, a modeling condition setting method, and a program that can solve the above-mentioned problems.

[0046] DESCRIPTION OF SYMBOLS 1 Welding system 2 Welding robot 3 Welding machine 4 Wire feeder 5 Torch 6 Modeled object 7 Positioning device 8 Sensor 9 Cooling machine 10 Control device 11 Shape data acquisition unit 12 Distance detection unit 13 Modeling condition setting unit 14 Control unit 15 Memory unit 100 Additive manufacturing system 900 Computer 901 CPU 902 Main memory unit 903 Auxiliary memory unit 904 Input / output interface 905 Communication interface

Claims

1. A manufacturing condition setting device that sets manufacturing conditions when additive manufacturing an object using the WAAM method, comprising: means for determining whether the difference between the measured value of the distance between the torch and the object to be manufactured is within an allowable range and the design value of said distance; and means for correcting a target welding position included in said manufacturing conditions so that said difference falls within said allowable range if said difference exceeds the allowable range, and for correcting a torch angle so that it matches the manufacturing direction based on the shape of the object to be manufactured at the corrected target welding position.

2. The molding condition setting device according to claim 1, further comprising: means for setting, as the molding condition, cooling of the object when the difference exceeds the allowable range and the difference has a magnitude that indicates an excessive temperature rise of the object.

3. A manufacturing condition setting device according to claim 1 or claim 2, wherein, in the case where the object to be manufactured has a shape that is manufactured by stacking layers in a vertical direction, the correction means corrects the target welding position upward by a value corresponding to the difference if the difference indicates that the torch and the object to be manufactured are closer than the tolerance range, and corrects the target welding position downward by a value corresponding to the difference if the difference indicates that the torch and the object to be manufactured are farther apart than the tolerance range.

4. The manufacturing condition setting device according to claim 1 or 2, wherein, when the object to be manufactured has an inclined shape, the correction means, if the difference indicates that the torch and the object to be manufactured are closer than the tolerance range, corrects the target welding position upward along the inclined direction by a value corresponding to the difference, and corrects the torch angle so that the position coincides with the manufacturing direction indicated by the shape of the object to be manufactured at the corrected target welding position and the tip of the torch faces the direction of the lower layer in the manufacturing process; and, if the difference indicates that the torch and the object to be manufactured are farther apart than the tolerance range, corrects the target welding position downward along the inclined direction by a value corresponding to the difference, and corrects the torch angle so that the position coincides with the manufacturing direction indicated by the shape of the object to be manufactured at the corrected target welding position and the tip of the torch faces the direction of the lower layer in the manufacturing process.

5. The molding condition setting device according to claim 2, wherein if the difference is equal to or less than a predetermined first threshold, the means for setting cooling determines to cool the object by spraying water or gas.

6. The molding condition setting device according to claim 5, wherein if the difference is equal to or greater than a predetermined second threshold value that is greater than the first threshold value, the means for setting cooling determines to temporarily suspend molding.

7. An additive manufacturing system for additively manufacturing an object using the WAAM method, comprising: a welding system having a torch and a sensor for measuring the distance to a fixed object in a fixed positional relationship with the torch; a control device for controlling the welding system; and the manufacturing condition setting device according to claim 1.

8. An additive manufacturing system for additively manufacturing an object using the WAAM method, comprising: a welding system having a torch, a sensor for measuring the distance to a fixed object in a fixed positional relationship with the torch, and a cooler for cooling the object; a control device for controlling the welding system; and the manufacturing condition setting device according to claim 2.

9. A computer-implemented method for setting building conditions for additive manufacturing of an object to be built using the WAAM method, the method comprising the steps of: determining whether or not a difference between a measured value of the distance between the torch and the object to be built and a design value of said distance is within an acceptable range; and, if said difference exceeds the acceptable range, correcting a target welding position included in said building conditions so that said difference falls within said acceptable range, and correcting the torch angle so that it matches the building direction based on the shape of the object to be built at the corrected target welding position.

10. A program that causes a computer to execute a process of setting the manufacturing conditions when additively manufacturing an object using the WAAM method, the process comprising the steps of: determining whether the difference between the measured value of the distance between the torch and the object to be manufactured is within an acceptable range; and, if the difference exceeds the acceptable range, correcting the target welding position included in the manufacturing conditions so that the difference falls within the acceptable range, and correcting the torch angle so that it matches the manufacturing direction based on the shape of the object to be manufactured at the corrected target welding position.

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