Monitoring method for fabrication process, additive fabrication device, and additive fabrication method

Abstract

A monitoring method for a fabrication process according to at least one embodiment of the present disclosure comprises: a step for irradiating a layer of a raw material powder with an energy beam to fuse and solidify the raw material powder of the layer and thereby fabricate a part of a fabrication product; a first detection step for detecting the presence or absence of a defect in the fabrication product while the fabrication step is performed; and a second detection step for measuring a surface shape of the fabrication product after the fabrication step has been performed and detecting the presence of a defect in the fabrication product on the basis of the surface shape of the fabrication product. The first detection step and the second detection step are performed each time the fabrication step is performed.

Description

Method for monitoring a manufacturing process, additive manufacturing apparatus, and additive manufacturing method

[0001] This application claims priority to Japanese Patent Application No. 2022-178799, filed with the Japan Patent Office on November 8, 2022, the contents of which are incorporated herein by reference.

[0002] Among the additive manufacturing methods for additively manufacturing three-dimensional objects, for example, the powder bed method uses an energy beam such as a light beam or an electron beam to irradiate metal powder, which is raw material powder laid in layers, to repeatedly melt and solidify the powder and form a three-dimensional object (model) (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2017-20422

[0004] In the area irradiated by the energy beam, the metal powder melts rapidly. This can result in defects in the molded object, such as cavities inside the object. Therefore, to ensure the quality of the molded object, it is necessary to perform non-destructive testing of the molded object after it has been molded. However, non-destructive testing after the molded object has been molded takes time and is costly.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to reduce the inspection time and costs required for inspection of an additive manufacturing object.

[0006] (1) A method for monitoring a manufacturing process according to at least one embodiment of the present disclosure includes: a step of forming a portion of an object by irradiating an energy beam onto a layer of raw material powder to melt and solidify the raw material powder in the layer; a first detection step of detecting whether or not the object has a defect while the manufacturing step is being performed; and a second detection step of measuring the surface shape of the object after the manufacturing step is performed and detecting whether or not the object has a defect based on the surface shape of the object, wherein the first detection step and the second detection step are performed each time the manufacturing step is performed.

[0007] (2) An additive manufacturing apparatus according to at least one embodiment of the present disclosure comprises: a powder bed formation unit having a base plate on which a layer is formed from supplied raw material powder; an energy beam irradiation unit capable of irradiating the layer with an energy beam; a first detection device configured to detect the presence or absence of defects in the object during irradiation with the energy beam; and a second detection device configured to measure the surface shape of the object after irradiating the energy beam and detect the presence or absence of defects in the object based on the surface shape of the object, wherein the powder bed formation unit is configured to detect the presence or absence of defects in the object with the first detection device and, after detecting the presence or absence of defects in the object with the second detection device, supply the raw material powder to form a layer of the raw material powder.

[0008] (3) An additive manufacturing method according to at least one embodiment of the present disclosure includes a step of detecting the presence or absence of defects in the manufactured object by the method for monitoring the manufacturing process according to (1) above.

[0009] According to at least one embodiment of the present disclosure, it is possible to reduce the inspection time and costs required for the inspection of an additive manufacturing object.

[0010] FIG. 1 is a schematic diagram illustrating the overall configuration of a three-dimensional additive manufacturing device to which a method for monitoring a manufacturing process according to at least one embodiment of the present disclosure can be applied; FIG. 2 is a flowchart illustrating a processing procedure in an additive manufacturing method according to a first embodiment using a three-dimensional additive manufacturing device; FIG. 3 is a diagram illustrating the emission intensity of light emitted from a test piece when modeling layers are formed sequentially on a test piece having an artificial defect, and the standard deviation of the emission intensity; FIG. 4 is a graph illustrating the relationship between the depth of a defect in a modeled object and the output of a light beam when repairing the defect in the modeled object; FIG. 5 is a diagram illustrating the scanning pattern of a light beam when repairing a defect in the modeled object; FIG. 6 is a diagram illustrating the scanning pattern of a light beam when repairing a defect in the modeled object; FIG. 7 is a diagram illustrating the scanning pattern of a light beam when repairing a defect in the modeled object; Fig. 10 is a flowchart showing the processing procedures in an additive manufacturing method according to a second embodiment using a three-dimensional additive manufacturing device. Fig. 11 is a flowchart showing the processing procedures in an additive manufacturing method according to a third embodiment using a three-dimensional additive manufacturing device. Fig. 12 is a flowchart showing the processing procedures in an additive manufacturing method according to a fourth embodiment using a three-dimensional additive manufacturing device. Fig. 13 is a schematic diagram showing the overall configuration of a three-dimensional additive manufacturing device, which is an additive manufacturing device to which the additive manufacturing method according to a sixth embodiment can be applied.

[0011] Several embodiments of the present disclosure will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure and are merely illustrative examples. For example, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express relative displacements with a tolerance or angle or distance to the extent that the same function is achieved. For example, expressions expressing the equality of things, such as "same," "equal," and "homogeneous," not only express strict equality, but also express tolerance or differences to the extent that the same function is achieved. For example, expressions expressing shapes such as a square or cylindrical shape not only express shapes such as a square or cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is achieved. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0012] (Regarding the Three-Dimensional Additive Manufacturing Apparatus 1) FIG. 1 is a schematic diagram showing the overall configuration of a three-dimensional additive manufacturing apparatus 1, which is an additive manufacturing apparatus to which a method for monitoring a manufacturing process according to at least one embodiment of the present disclosure can be applied. The three-dimensional additive manufacturing apparatus (additive manufacturing apparatus) 1 is an apparatus for producing a three-dimensionally shaped object 15 by performing additive manufacturing by irradiating a metal powder, which is a raw material powder laid in layers, with a light beam 71 as an energy beam, and is capable of performing additive manufacturing using the powder bed method. The three-dimensional additive manufacturing apparatus 1 shown in FIG. 1 can form parts such as rotor blades and stator blades of turbines such as gas turbines and steam turbines, or combustor liner, transition pieces, and nozzles.

[0013] The three-dimensional additive manufacturing apparatus 1 shown in FIG. 1 includes a storage unit 31 for raw material powder 30. The three-dimensional additive manufacturing apparatus 1 shown in FIG. 1 also includes a powder bed forming unit 5 having a base plate 2 on which a powder bed 8 is formed by sequentially stacking layers 8a of raw material powder 30 supplied from the storage unit 31. The three-dimensional additive manufacturing apparatus 1 shown in FIG. 1 also includes a light beam irradiation device 20 including a light beam irradiation unit 21 capable of irradiating a light beam 71 onto the powder bed 8 and a light beam control unit 22 that controls the light beam irradiation unit 21. The three-dimensional additive manufacturing apparatus 1 shown in FIG. 1 also includes a powder laying unit 10 (described later), a drive cylinder 2a of the base plate 2, and a control unit 80 that controls the entire three-dimensional additive manufacturing apparatus 1. The three-dimensional additive manufacturing apparatus 1 shown in FIG. 1 also includes a first detection device 40, a second detection device 50, and a flaw detection device 60.

[0014] The base plate 2 serves as a foundation on which the object 15 is formed. The base plate 2 is disposed inside a generally cylindrical cylinder 4 having a vertical central axis so that it can be raised and lowered by a drive cylinder 2a. During the forming operation, a new layer 8a is formed on the powder bed 8 formed on the base plate 2 by laying raw material powder 30 on the upper layer side each time the base plate 2 is lowered in each cycle.

[0015] The three-dimensional additive manufacturing device 1 shown in FIG. 1 includes a powder laying unit 10 for laying raw material powder 30 on a base plate 2 to form a layer 8a from the raw material powder 30. The powder laying unit 10 supplies raw material powder 30 from a storage unit 31 to the upper surface of the base plate 2 and flattens the surface to form a layer 8a having a substantially uniform thickness across the entire upper surface of the base plate 2. The powder bed 8, in which the layers 8a formed in each cycle are sequentially stacked, is selectively melted and solidified by irradiation with a light beam 71 from a light beam irradiation unit 21. In the next cycle, raw material powder 30 is again laid on the upper layer by the powder laying unit 10 to form a new layer 8a, thereby stacking the layers in layers.

[0016] The raw powder 30 supplied from the powder depositing section 10 is a powdered substance that will be used as the raw material for the molded object 15, and a wide range of metal materials, such as iron, copper, aluminum, or titanium, and non-metallic materials, such as ceramics, can be used.

[0017] 1 , the powder bed forming unit 5 and the powder laying unit 10 are housed in a chamber 9. The chamber 9 is provided with windows 9a at multiple locations that can transmit the light beam 71, the light beam input / output to / from the second detection device 50 described below, and the light beam input / output to / from the flaw detection device 60. Protective glass or the like is arranged in the windows 9a so that the light beam 71 and the light beam can pass through while maintaining airtightness between the inside and outside of the chamber 9.

[0018] The control unit 80 is a control unit of the three-dimensional additive manufacturing apparatus 1 shown in Fig. 1 and is configured by, for example, an electronic processing device such as a computer. Information regarding the scanning position of the light beam 71 for each layer 8a is input to the control unit 80 as information necessary for manufacturing the model 15. The information regarding the irradiation position of the light beam 71 for each layer 8a may be input, for example, from an external device and stored, for example, in a storage unit (not shown) of the control unit 80.

[0019] The control unit 80 is configured to control the driving of the drive cylinder 2 a of the powder bed forming unit 5. The control unit 80 is also configured to be able to control the first detection device 40, the second detection device 50, and the flaw detection device 60 in cooperation with each other.

[0020] (Light beam irradiation device 20) The light beam irradiation device 20 is a device for irradiating the powder bed 8 with the light beam 71, and has the light beam irradiation unit 21 capable of irradiating the light beam 71 as described above, and the light beam control unit 22 that controls the light beam irradiation unit 21. The light beam control unit 22 is configured by an electronic calculation device such as a computer, and is configured to control the irradiation position of the light beam 71 irradiated by the light beam irradiation unit 21 based on information regarding the irradiation position of the light beam 71 for each layer 8 a received from the control unit 80.

[0021] (First Detector 40) The first detector 40 is a device for detecting the presence or absence of defects in the molded object 15 based on the light emitted from the molded object 15 when irradiated with the light beam 71, i.e., the light emission intensity of the light emitted from the molten pool and plume formed when irradiated with the light beam 71, and is, for example, a plasma light emission monitor capable of detecting plasma light emission during the process in real time. The first detector 40 includes a light detector 41 for detecting the light emitted from the molded object 15 and an emission monitor controller 42 capable of detecting the presence or absence of defects in the molded object 15 based on the light emission intensity of the light detected by the light detector 41. The emission monitor controller 42 is, for example, configured by an electronic processing device such as a computer. In the three-dimensional additive manufacturing apparatus 1 shown in FIG. 1 , the light emitted from the molded object 15 when irradiated with the light beam 71 is reflected by the beam splitter 6 and enters the light detector 41.

[0022] (Second Detection Device 50) The second detection device 50 is a shape measurement device capable of measuring the shape of the build surface area, i.e., the top surface of the object 15 on the base plate 2 and the surface of the powder bed 8. In some embodiments, the second detection device 50 is, for example, an optical scanner based on a fringe projection method. The second detection device 50 includes a projection unit 51, which is a projector configured to project a fringe pattern (striped pattern) onto the build surface area on the base plate 2, an imaging unit 52 configured to capture an image of the fringe pattern projected onto the build surface area, and an unevenness detection unit 53 configured to detect unevenness in the build surface area based on the image data acquired by the imaging unit 52. The unevenness detection unit 53 is configured by an electronic processing device such as a computer, and is configured to detect the presence or absence of defects in the layer 8 a of the raw material powder 30 and the presence or absence of defects in the build surface area based on the state of unevenness in the build surface area.

[0023] The defects of the layer 8 a detected by the second detection device 50 are undesired irregularities of the layer 8 a, etc. The defects of the object 15 detected by the second detection device 50 are undesired deformations of the top surface of the object 15, opening defects, etc.

[0024] (Flaw Detection Device 60) The flaw detection device 60 is a flaw detection device for detecting defects in the shaped object 15, and in some embodiments, is a flaw detection device using, for example, a laser ultrasonic method. The flaw detection device 60 includes a laser irradiation device 61 configured to be able to irradiate the shaped object 15 with pulsed laser light to generate ultrasonic waves in the shaped object 15, a laser interferometer 62 configured to irradiate the shaped object 15 with the laser light and receive the reflected light to measure vibrations, i.e., displacement, of the surface of the shaped object 15, and a flaw detection control unit 63. The flaw detection control unit 63 is formed by an electronic processing device such as a computer, and is configured to be able to detect the presence or absence of defects inside the shaped object 15, as well as the position and size of the defects, based on the vibrations of the surface of the shaped object 15 detected by the laser interferometer 62.

[0025] (Issues in Conventional Additive Manufacturing Processes) The raw material powder 30 melts rapidly in the region irradiated with the energy beam. This may result in defects in the molded object 15, such as the formation of cavities inside the molded object 15. Therefore, in order to ensure the quality of the molded object 15, it is necessary to perform non-destructive testing of the molded object 15 after the molding of the molded object 15 is completed. However, non-destructive testing performed after the molding of the molded object 15 is completed does not always detect all defects. Furthermore, non-destructive testing takes time and is costly.

[0026] Therefore, in some embodiments of the three-dimensional additive manufacturing device 1, the presence or absence of defects in the object 15 or the powder bed 8 is detected for each layer 8a of the raw material powder 30 as follows, and the detected defects are repaired.

[0027] (Regarding the additive manufacturing method according to the first embodiment using the three-dimensional additive manufacturing device 1) Fig. 2 is a flowchart showing the processing procedure in the additive manufacturing method according to the first embodiment using the above-mentioned three-dimensional additive manufacturing device 1. The following description will be given with reference to the flowchart in Fig. 2. Note that in the additive manufacturing method according to the first embodiment, the manufacturing process is monitored as follows.

[0028] In step S11, the control unit 80, more specifically, the arithmetic unit of the control unit 80, controls the powder laying unit 10 to lay down the raw material powder 30. As a result, a layer 8a is formed from the raw material powder 30 supplied from the storage unit 31.

[0029] Next, in step S13, the control unit 80 controls the second detection device 50 to detect the presence or absence of defects in the layer 8a formed by the raw material powder 30 based on the state of unevenness in the build surface area. As a result, the second detection device 50 projects a fringe pattern (striped pattern) onto the build surface area on the base plate 2 and detects unevenness in the build surface area based on the image data acquired by the imaging unit 52. Then, the second detection device 50 (unevenness detection unit 53) detects the presence or absence of defects in the layer 8a based on the detection result of the unevenness in the build surface area and outputs the result to the control unit 80.

[0030] In step S15, the control unit 80 determines whether or not there is a defect in the layer 8a based on the information from the second detection device 50. If it is determined that there is a defect in the layer 8a, the control unit 80 returns to step S11 and controls the powder laying unit 10 to lay down raw material powder 30. As a result, the raw material powder 30 is re-laid.

[0031] If it is determined that no defects exist in the layer 8 a, the control unit 80 proceeds to step S21 and controls the light beam irradiation device 20 to irradiate the light beam 71. As a result, the light beam irradiation device 20 irradiates the light beam 71 based on the information regarding the irradiation position of the light beam 71 for each layer 8 a received from the control unit 80.

[0032] Furthermore, the control unit 80 controls the first detection device 40 to detect the presence or absence of defects in the object 15 in step S23, simultaneously with the irradiation of the light beam 71 in step S21. As a result, the first detection device 40 detects the presence or absence of defects in the object 15 based on the emission intensity of light emitted from the object 15.

[0033] When an energy beam such as the light beam 71 is irradiated onto the layer 8 a of the raw material powder 30, if the irradiation state of the energy beam changes for some reason, for example, due to a decrease in the output of the energy beam, the light emission intensity of the light emitted from the model 15 will change. Furthermore, an undesired change in the irradiation state of the energy beam may result in insufficient melting of the raw material powder 30, causing defects. With the three-dimensional additive manufacturing device 1 according to this embodiment, it is possible to determine, for example, whether a malfunction or the like has occurred in the three-dimensional additive manufacturing device 1, based on a change in the light emission intensity of the light emitted from the model 15.

[0034] Note that, for example, if a change in the light emission intensity occurs due to a malfunction of the three-dimensional additive manufacturing device 1, a malfunction may occur in the layer 8 a currently being formed by irradiating the light beam 71 due to insufficient melting of the raw material powder 30. Therefore, for example, if a change in the light emission intensity occurs due to a malfunction of the three-dimensional additive manufacturing device 1, a malfunction may occur in the three-dimensional additive manufacturing device 1, or a malfunction may occur in the layer 8 a currently being formed by irradiating the light beam 71.

[0035] Note that the change in light emission intensity caused by a malfunction or the like of the three-dimensional additive manufacturing apparatus 1 is not a change in light emission intensity caused by a malfunction or the like of the object 15 below the layer 8a currently being manufactured by irradiating it with the light beam 71, as will be described later. Therefore, even if a change in light emission intensity occurs due to a malfunction or the like of the three-dimensional additive manufacturing apparatus 1, there may be cases where repair of the defect in step S29 or step S37, which will be described later, is not required.

[0036] Furthermore, as a result of careful investigation by the inventors, it was found that when an energy beam such as light beam 71 is irradiated onto layer 8a of raw material powder 30, the intensity of the light emitted from the molded object 15 changes when there is a defect such as a cavity in the base, i.e., in the molding layer below layer 8a currently being irradiated with the energy beam, compared to when there is no defect, due to changes such as differences in thermal conduction and changes in the size of the molten pool, and the intensity of the light emitted from the molded object 15 changes.

[0037] 3 shows the light emission intensity and standard deviation of the light emission intensity of the light emitted from a test piece when a modeling layer is formed sequentially on the test piece having a simulated defect. The leftmost diagram in FIG. 3 shows the light emission intensity and standard deviation of the light emission intensity when a 0.5 mm square simulated defect is generated by not irradiating the 0.5 mm square area in the center of the diagram with the light beam 71. The modeling layer generated in this manner is referred to as the final layer of the simulated defect.

[0038] The second diagram from the left in Figure 3 shows the light emission intensity and standard deviation of the light emission intensity when a light beam 71 is irradiated onto raw material powder 30 laid directly on the final layer of simulated defects. The modeling layer generated in this manner is called a defect capping layer. If the final layer of simulated defects described above is considered the first layer, the defect capping layer corresponds to the second layer. Figure 3 shows that when the defect capping layer is modeled, the light emission intensity and standard deviation of the light emission intensity in the region directly above the simulated defects are affected by the simulated defects in the layer next to the defect capping layer, i.e., the final layer of simulated defects, which is the layer below.

[0039] The rightmost diagram in Figure 3 shows the light emission intensity and standard deviation of the light emission intensity when a light beam 71 is irradiated onto raw material powder 30 laid directly on the defect cap layer. The modeling layer generated in this manner is referred to as the post-cap modeling layer. If the final layer of the simulated defect described above is considered the first layer, the post-cap modeling layer corresponds to the third layer. Figure 3 shows that during modeling of the post-cap modeling layer, the light emission intensity and standard deviation of the light emission intensity in the region directly above the simulated defect differ from the light emission intensity and standard deviation of the light emission intensity in other regions due to the influence of the simulated defect in the layer next to the post-cap modeling layer (the defect cap layer), i.e., the final layer of the simulated defect, which is the layer two layers below.

[0040] The three-dimensional additive manufacturing apparatus 1 according to this embodiment can detect the presence or absence of defects in the manufacturing layers below the topmost manufacturing layer of the object 15, i.e., the manufacturing layers below the layer 8a currently being irradiated with the light beam 71, based on changes in the light emission intensity of light emitted from the object 15 when the light beam 71 is irradiated onto the layer 8a of the raw material powder 30. In other words, the three-dimensional additive manufacturing apparatus 1 according to this embodiment can detect the presence of defects, for example, in the object 15 below the layer 8a currently being manufactured by irradiating the light beam 71.

[0041] Therefore, with the three-dimensional additive manufacturing device 1 according to this embodiment, it is possible to detect, based on the light emission intensity of the light emitted from the model 15 when irradiated with the light beam 71, whether or not there is a possibility of a malfunction occurring in the three-dimensional additive manufacturing device 1, whether or not there is a possibility of a malfunction occurring in the layer 8a currently being irradiated with the light beam 71, and whether or not there are any defects such as cavities in the modeling layers below the layer 8a.

[0042] In step S25, the control unit 80 determines whether or not the object 15 has a defect, based on the information from the first detection device 40. If it is determined that the object 15 has a defect, the control unit 80 proceeds to step S27 and controls the flaw detection device 60 to inspect the object 15 and acquire the state of the defect. As a result, the flaw detection device 60 inspects the object 15 as described above and detects the state of the defect, i.e., the presence or absence of a defect inside the object 15, as well as the position and size of the defect, and outputs the detection result to the control unit 80.

[0043] Next, in step S29, the control unit 80 controls the light beam irradiation device 20 to repair the defect based on the state of the defect acquired by the flaw detection device 60 in step S27. As a result, the light beam irradiation device 20 irradiates the shaped object 15 with the light beam 71 based on the information regarding the position and size of the defect received from the control unit 80. In this way, the defect inside the shaped object 15 is repaired. Note that the details of the defect repair by the light beam irradiation device 20 will be described later.

[0044] If it is determined in step S25 that no defects exist in the object 15, or if the above-described step S29 has been performed, the process proceeds to step S31, where the control unit 80 controls the second detection device 50 to detect the presence or absence of defects in the object 15 based on the state of unevenness in the printing surface area. As a result, the second detection device 50 projects a fringe pattern (striped pattern) onto the printing surface area on the base plate 2, and detects unevenness in the printing surface area based on the image data acquired by the imaging unit 52. Then, the second detection device 50 (unevenness detection unit 53) detects the presence or absence of defects on the top surface of the object 15 based on the detection result of unevenness in the printing surface area, and outputs the detection result to the control unit 80.

[0045] In step S33, the control unit 80 determines whether or not there is a defect on the top surface of the object 15, based on the information from the second detection device 50. If it is determined that there is a defect on the top surface of the object 15, the control unit 80 proceeds to step S35, and controls the flaw detection device 60 to inspect the object 15 and obtain the state of the defect. As a result, the flaw detection device 60 inspects the object 15 as described above, obtains the state of the defect, and outputs the detection result to the control unit 80.

[0046] Next, in step S37, the control unit 80 controls the light beam irradiation device 20 to repair the defect based on the state of the defect acquired by the flaw detection device 60 in step S35. As a result, the light beam irradiation device 20 irradiates the object 15 with the light beam 71 based on the information regarding the position and size of the defect received from the control unit 80. As a result, the defect in the object 15 is repaired.

[0047] If it is determined in step S33 that no defects exist in the object 15, or if the above-described step S37 has been performed, the process proceeds to step S41, where the control unit 80 determines whether or not the formation of the object 15 has been completed. If it is determined that the formation of the object 15 has not been completed, the process proceeds to step S43, where the control unit 80 outputs a drive signal to the drive cylinder 2a to lower the base plate 2 by an amount equivalent to the thickness of one layer 8a. As a result, the base plate 2 is lowered by an amount equivalent to the thickness of one layer 8a. After step S43 has been performed, the process returns to step S11.

[0048] When it is determined in step S41 that the formation of the object 15 has been completed, the control unit 80 ends the formation of the object 15 .

[0049] The method for monitoring a modeling process performed when a model 15 is manufactured using the three-dimensional additive manufacturing apparatus 1 according to this embodiment includes step S11, which is a step of supplying raw material powder 30 and forming a layer 8a of the raw material powder 30. The method for monitoring a modeling process according to this embodiment also includes step S21, which is a step of irradiating the layer 8a with a light beam 71, which is an energy beam, to melt and solidify the raw material powder 30 in the layer 8a, thereby manufacturing a part of the model 15. The method for monitoring a modeling process according to this embodiment also includes step S23, which is a first detection step of detecting the presence or absence of a defect in the model 15 while step S21 is being performed. The method for monitoring a modeling process according to this embodiment also includes step S31, which is a second detection step of measuring the surface shape of the model 15 after step S21 is performed, and detecting the presence or absence of a defect in the model 15 based on the surface shape of the model 15. In the method for monitoring a modeling process according to this embodiment, step S23, which is the first detection step, and step S31, which is the second detection step, are performed each time step S21 is performed.

[0050] According to the method for monitoring a modeling process of this embodiment, step S23, which is the first detection step, is performed while step S21 is being performed, thereby significantly reducing the inspection time. Furthermore, in step S31, which is the second detection step, the presence or absence of defects in the modeled object 15 is detected based on the surface shape of the modeled object 15, allowing the inspection to be completed in a relatively short time. Therefore, according to the method for monitoring a modeling process of this embodiment, the inspection time for the modeled object 15 can be reduced. Furthermore, according to the method for monitoring a modeling process of this embodiment, by performing step S23, which is the first detection step, and step S31, which is the second detection step, every time step S21 is performed, it is possible to omit non-destructive testing after the modeling of the modeled object 15 is completed, thereby reducing the inspection time and costs for the modeled object 15. According to the method for monitoring the molding process of this embodiment, by performing the first detection step S23 and the second detection step S31 each time step S21 is performed, the accuracy of detecting defects in the molded object 15 can be improved compared to when the first detection step and the second detection step are performed alone, and therefore the quality of the molded object 15 can be improved.

[0051] According to the additive manufacturing method using the method for monitoring the manufacturing process according to this embodiment, it is possible to obtain a high-quality manufactured object 15 while reducing the inspection time and costs required for the inspection of the manufactured object 15.

[0052] In the method for monitoring a modeling process according to this embodiment, in step S23, the presence or absence of a defect in the model 15 is detected based on the emission intensity of light emitted from the model 15 when the light beam 71 is irradiated in step S21 where the model is being modeled. This allows step S23 to be performed relatively easily with a relatively simple device configuration while step S21 is being performed, thereby suppressing an increase in the cost of the device for performing step S23.

[0053] In the method for monitoring a modeling process according to this embodiment, in step S31, the surface shape of the model 15 is measured based on an image obtained by capturing an image of a pattern projected onto the surface of the model 15. This allows step S31 to be performed relatively easily with a relatively simple device configuration, which not only reduces the time required to perform step S31 but also suppresses an increase in the cost of the device required to perform step S31.

[0054] In the method for monitoring a molding process according to this embodiment, when a defect is detected in step S23 or step S31, the object 15 is inspected to acquire the state of the defect (steps S27 and S35), thereby making it possible to grasp the state of the defect in more detail.

[0055] In the method for monitoring a molding process according to this embodiment, the state of the defect is acquired by a laser ultrasonic method in steps S27 and S35, which makes it possible to grasp the state of the defect in more detail in a non-destructive manner.

[0056] The method for monitoring the manufacturing process according to this embodiment includes, after performing step S11, which is a step of forming the layer 8 a, and before performing step S21, which is a step of manufacturing, step S13, which is a step of measuring the surface shape of the layer 8 a and detecting the presence or absence of defects in the layer 8 a based on the surface shape of the layer 8 a. This makes it possible to grasp the quality of the condition of the layer 8 a formed by laying down the raw material powder 30.

[0057] The method for monitoring a manufacturing process according to this embodiment includes a step (step S11) of supplying raw material powder 30 and re-forming layer 8 a of raw material powder 30 when a defect is detected in layer 8 a in step S13. This improves the soundness of layer 8 a formed by laying raw material powder 30.

[0058] The three-dimensional additive manufacturing apparatus 1 according to this embodiment includes a powder bed formation unit 5 having a base plate 2 on which a layer 8 a is formed using supplied raw material powder 30. The three-dimensional additive manufacturing apparatus 1 according to this embodiment includes a light beam irradiation device 20 as an energy beam irradiation unit capable of irradiating the layer 8 a with a light beam 71, which is an energy beam. The three-dimensional additive manufacturing apparatus 1 according to this embodiment also includes a first detection device 40 configured to detect the presence or absence of defects in the object 15 during irradiation with the light beam 71. The three-dimensional additive manufacturing apparatus 1 according to this embodiment also includes a second detection device 50 configured to measure the surface shape of the object 15 after irradiating it with the light beam 71 and detect the presence or absence of defects in the object 15 based on the surface shape of the object 15. The powder bed formation unit 5 is configured to detect the presence or absence of defects in the object 15 using the first detection device 40 and, after the presence or absence of defects in the object 15 is detected using the second detection device 50, supply raw material powder 30 to form the layer 8 a of the raw material powder 30.

[0059] According to the three-dimensional additive manufacturing apparatus 1 of this embodiment, the presence or absence of defects in the object 15 is detected while the light beam 71 is being irradiated for manufacturing, thereby significantly reducing the inspection time. Furthermore, the presence or absence of defects in the object 15 can be detected by the second detection device 50 based on the surface shape of the object 15, allowing for inspection in a relatively short time. Therefore, the three-dimensional additive manufacturing apparatus 1 of this embodiment can reduce the inspection time for the object 15. Furthermore, according to the three-dimensional additive manufacturing apparatus 1 of this embodiment, the presence or absence of defects can be detected by the first detection device 40 and the second detection device 50 each time each layer 8a is manufactured, thereby omitting non-destructive inspection after manufacturing of the object 15 is completed, thereby reducing the inspection time and costs for the object 15.

[0060] (Regarding Defect Repair Using the Light Beam Irradiation Device 20) Fig. 4 is a graph illustrating the relationship between the depth De of a defect and the output of the light beam 71 when repairing a defect in the object 15. Figs. 5A to 5G are diagrams illustrating the scanning pattern of the light beam 71 when repairing a defect in the object 15.

[0061] (Regarding the output of the light beam 71 when repairing a defect) In the three-dimensional additive manufacturing device 1 according to this embodiment, when repairing a defect in the model 15 in the above-mentioned steps S29 and S37, the defect is repaired by irradiating the light beam 71 under irradiation conditions set based on the state of the defect acquired in step S27 or step S35.

[0062] Specifically, if the defect depth De obtained in step S27 or step S35 is less than a specified depth De1, the control unit 80 controls the light beam irradiation device 20 to irradiate the light beam 71 at the first output P1 to repair the defect. As a result, the light beam irradiation device 20 irradiates the light beam 71 at the first output P1 (see FIG. 4 ). Here, the defect depth De is, for example, the distance from the surface of the object 15 to the bottom of a cavity or the like. The first output P1 is an output that can remelt at least the surface of the object 15. In other words, because the surface of the object 15 cannot be remelted unless the output of the irradiated light beam 71 exceeds a certain threshold, if the defect depth De is less than the specified depth De1, the light beam 71 is output at a first output P1 that is equal to or greater than the threshold, regardless of the defect depth De.

[0063] If the defect depth De acquired in step S27 or step S35 is equal to or greater than a specified depth De1, the control unit 80 controls the light beam irradiation device 20 to repair the defect by irradiating the light beam 71 at a second output P2 that is greater than the first output P1 and that increases as the defect depth De increases. As a result, the light beam irradiation device 20 irradiates the light beam 71 at the second output P2 (see FIG. 4).

[0064] In the three-dimensional additive manufacturing apparatus 1 according to this embodiment, defects in the object 15 are repaired in the above-described steps S29 and S37, and therefore the defects can be repaired during the manufacturing of the object 15. This makes it possible to omit non-destructive testing after the manufacturing of the object 15 is completed, and reduces the time and costs required for inspecting the object 15.

[0065] By setting the output of the light beam 71 as described above when repairing a defect in the object 15 in steps S29 and S37, the defect can be repaired with an output of the light beam 71 that corresponds to the defect depth De, thereby improving the reliability of defect repair. Furthermore, when repairing a defect in the object 15 in steps S29 and S37, even if the defect depth De is less than the specified depth De1, the light beam 71 with the first output P1 is irradiated, thereby preventing the occurrence of a problem in which the surface of the object 15 cannot be re-melted during defect repair.

[0066] (Regarding Scanning of the Light Beam 71 During Defect Repair) In the three-dimensional additive manufacturing apparatus 1 according to this embodiment, when repairing a defect in the model 15 in steps S29 and S37 described above, whether or not to scan the light beam 71 is determined based on the maximum dimension dmax of the defect when the defect is viewed from above the model 15. In the three-dimensional additive manufacturing apparatus 1 according to this embodiment, if the maximum dimension dmax of the defect is less than twice the beam width db of the light beam 71 (dmax<2×db), the defect is repaired by irradiating the light beam 71 without scanning. In the three-dimensional additive manufacturing apparatus 1 according to this embodiment, if the maximum dimension dmax of the defect is twice or more the beam width db of the light beam 71 (dmax≧2×db), the defect is repaired by irradiating the light beam 71 while scanning. This allows the light beam 71 to be irradiated under irradiation conditions appropriate for the size of the defect.

[0067] When repairing defects by irradiating the light beam 71 while scanning, scanning may be performed using the scanning patterns shown in Figures 5A to 5G, for example. Note that in Figures 5A to 5G, the scanning patterns of the light beam 71 are represented by arrows. For example, the scanning pattern shown in Figure 5A is an example of scanning the light beam 71 along the circumferential direction. For example, the scanning pattern shown in Figure 5B is an example of scanning the light beam 71 along the sides of a rectangle. For example, the scanning pattern shown in Figure 5C is an example of scanning the light beam 71 by moving it back and forth linearly between one side and the other side within a certain area so as to fill the area.

[0068] For example, the scanning pattern shown in Figure 5D is an example of scanning the light beam 71 along the circumferential direction so as to draw multiple concentric circles. For example, the scanning pattern shown in Figure 5E is an example of scanning the light beam 71 along the sides of a rectangle so as to draw multiple concentric rectangles. For example, the scanning pattern shown in Figure 5F is an example of scanning the light beam 71 along the circumferential direction and scanning the light beam 71 so as to linearly reciprocate between one side and the other within a circular area so as to fill the area. For example, the scanning pattern shown in Figure 5G is an example of scanning the light beam 71 along the sides of a rectangle and scanning the light beam 71 so as to linearly reciprocate between one side and the other within the rectangular area so as to fill the area.

[0069] The scanning pattern when repairing defects by scanning and irradiating the light beam 71 is not limited to the above-described scanning pattern.

[0070] (Layered Manufacturing Method According to Second Embodiment) The layered manufacturing method according to the second embodiment will now be described. Fig. 6 is a flowchart showing the processing steps in the layered manufacturing method according to the second embodiment using the above-described three-dimensional layered manufacturing device 1. In the following description, the same processes as those in the layered manufacturing method according to the first embodiment will be denoted by the same reference numerals, and detailed description thereof may be omitted.

[0071] In the additive manufacturing method according to the second embodiment, even if it is determined that there is a defect in the object 15 based on information from the first detection device 40, or that there is a defect on the top surface of the object 15 based on information from the second detection device 50, if it is determined that the defect in the object 15 detected by the first detection device 40 or the second detection device 50 is minute, the method moves on to the next process without performing any process to repair the defect in the object 15.

[0072] The processes from step S11 to step S25 in Fig. 6 are the same as the processes from step S11 to step S25 in Fig. 2. If a negative judgment is made in step S25, the control unit 80 proceeds to step S31. If a positive judgment is made in step S25, the control unit 80 proceeds to step S61, where the control unit 80 determines whether the defect in the object 15 detected in step S23 is minor. If the control unit 80 determines in step S61 that the defect in the object 15 detected in step S23 is minor, the control unit 80 proceeds to step S31 without performing steps S27 and S29. If the control unit 80 determines in step S61 that the defect in the object 15 detected in step S23 is not minor, the control unit 80 proceeds to step S27.

[0073] The processes from step S27 to step S33 in Fig. 6 are the same as the processes from step S27 to step S33 in Fig. 2. If a negative judgment is made in step S33, the control unit 80 proceeds to step S41. If a positive judgment is made in step S33, the control unit 80 proceeds to step S63, where the control unit 80 determines whether the defect in the object 15 detected in step S31 is minor. If the control unit 80 determines in step S63 that the defect in the object 15 detected in step S31 is minor, the control unit 80 proceeds to step S41 without performing steps S35 and S37. If the control unit 80 determines in step S63 that the defect in the object 15 detected in step S31 is not minor, the control unit 80 proceeds to step S35.

[0074] The processes from step S35 onwards in Fig. 6 and the processes from step S41 onwards in Fig. 6 are the same as the processes from step S35 onwards in Fig. 2 and the processes from step S41 onwards in Fig. 2. Note that if it is determined in step S61 that the defect in the model 15 detected in step S23 is minute, or if it is determined in step S63 that the defect on the top surface of the model 15 detected in step S31 is minute, the three-dimensional additive manufacturing apparatus 1 may be configured to notify the operator of the three-dimensional additive manufacturing apparatus 1 that the defect in the model 15 is minute or that the defect in the model 15 is minute.

[0075] (Layered Manufacturing Method According to Third Embodiment) The layered manufacturing method according to the third embodiment will be described below. FIG. 7 is a flowchart showing the processing steps in the layered manufacturing method according to the third embodiment using the above-described three-dimensional layered manufacturing device 1. In the following description, the same processes as those in the layered manufacturing method according to the first embodiment and the layered manufacturing method according to the second embodiment will be denoted by the same reference numerals, and detailed description thereof may be omitted. The processing from step S11 to step S21 in FIG. 7 is the same as the processing from step S11 to step S21 in FIG. 2. After step S21 in FIG. 7 is performed, the process proceeds to step S51, and after step S51 is performed, the process proceeds to step S53. The processing contents of steps S51 and S53 in the layered manufacturing method according to the third embodiment will be described below.

[0076] In some embodiments of the additive manufacturing method, the emission intensity of light detected by the light detection unit 41 is continuously acquired, more specifically, at every minute scanning distance, during scanning with the light beam 71. The inventors extracted, for each layer, the maximum value Smax of the multiple emission intensity measurements acquired during the manufacturing of one modeling layer, the average value Save of the multiple emission intensity measurements, and the minimum value Smin of the multiple emission intensity measurements, and investigated their trends.

[0077] After careful consideration by the inventors, it was found that when there are no defects (voids) inside the molded object 15, or if there are any, they are very small defects, the maximum value Smax, the average value Save, and the minimum value Smin are relatively stable in all molding layers.

[0078] As a result of careful consideration by the inventors, it was found that when a defect that cannot be considered minute exists inside the molded object 15, the average value Save only fluctuates slightly during molding of the molding layer in which the defect exists, and it is difficult to determine whether or not a defect exists inside the molded object 15 based on changes in the average value Save. As a result of careful consideration by the inventors, it was found that when a defect that cannot be considered minute exists inside the molded object 15, the minimum value Smin is relatively stable in all molding layers.

[0079] However, after careful consideration by the inventors, it was found that when there is a defect inside the molded object 15 that is not considered to be tiny, the maximum value Smax detected during molding of the layer in which the defect (void) existed inside the molded object 15 will be a relatively large value compared to the maximum value Smax when there is no defect (void) inside the molded object 15, or if there is a defect, it is a tiny defect.

[0080] Therefore, in the additive manufacturing method according to the third embodiment, when determining whether or not the object 15 has a defect based on information from the first detection device 40, attention is paid to the maximum value Smax of the multiple emission intensity measurements acquired during the production of one modeling layer. That is, in the additive manufacturing method according to the third embodiment, the average value of a predetermined number of the emission intensity measurements acquired during the production of one modeling layer, in descending order of value, is set as the representative value Rv of the emission intensity of that modeling layer. Note that if the predetermined number is 1, the representative value Rv is the maximum value of the multiple emission intensity measurements acquired during the production of one modeling layer. Alternatively, among the multiple emission intensity measurements acquired during the production of one modeling layer, a predetermined percentage of the total number of measurements acquired during the production of one modeling layer are extracted in descending order of value, and the average value of these measurements is set as the representative value Rv of the emission intensity of that modeling layer. In the additive manufacturing method according to the third embodiment, the presence or absence of a defect in the object 15 is detected based on this representative value Rv and a predetermined reference value Ref. That is, in step S51, the control unit 80 acquires the representative value Rv from the detection result of the emission intensity by the first detection device 40. Then, as will be described later, the control unit 80 determines the presence or absence of a defect in the object 15 based on the representative value Rv and the predetermined reference value Ref. Note that in step S51, the control unit 80 may also determine the presence or absence of a defect in the object 15 as performed in step S23 of FIG. 2 according to the first embodiment described above.

[0081] Here, the reference value Ref is a value that is predetermined as the maximum value Smax that can be measured when there is no defect (void) inside the object 15, or when the defect, if any, is very small. This value may be, for example, an average value of the maximum values ​​Smax obtained by forming a large number of objects 15 under the same irradiation conditions as those of the light beam 71 when forming the object 15, or may be, for example, an average value of the maximum values ​​Smax obtained when a test object 15 is formed in advance under the same irradiation conditions as those of the light beam 71 when forming the object 15.

[0082] As described above, when a defect that cannot be considered minute exists inside the object 15, the maximum value Smax detected during the modeling of the layer in which the defect (void) exists inside the object 15 is relatively larger than the maximum value Smax when no defect (void) exists inside the object 15 or when the defect (void) is very small even if it exists inside the object 15. Therefore, the representative value Rv during the modeling of the layer in which the defect (void) exists inside the object 15 is relatively larger than the predetermined reference value Ref. In other words, there is a correlation between the comparison result of the representative value Rv and the reference value Ref and the presence or absence of a defect in the object 15.

[0083] In the method for monitoring a modeling process in the additive manufacturing method according to the third embodiment, in the first detection step (step S51), at least one of a plurality of measurement values ​​of the emission intensity obtained by measuring the emission intensity multiple times during one modeling step (step S21) may be selected in descending order of emission intensity as a representative value Rv of the emission intensity during one modeling step, and the presence or absence of a defect in the model 15 may be detected based on the representative value Rv and a predetermined reference value Ref. According to the additive manufacturing method according to the third embodiment, the presence or absence of a defect in the model 15 can be detected based on the representative value Rv and the reference value Ref, thereby improving the accuracy of detecting the presence or absence of a defect in the model 15.

[0084] More specifically, in the additive manufacturing method according to the third embodiment, the presence or absence of a defect in the object 15 is detected based on whether the representative value Rv is equal to or greater than a threshold value Th determined based on the reference value Ref. Here, the threshold value Th is a value that is larger than the reference value Ref by a specified percentage. For example, the threshold value Th may be 1.5 times the reference value Ref.

[0085] That is, in step S51, the control unit 80 compares the representative value Rv with the threshold value Th, and if the representative value Rv is less than the threshold value Th, determines that there is no defect in the object 15. In step S51, the control unit 80 compares the representative value Rv with the threshold value Th, and if the representative value Rv is equal to or greater than the threshold value Th, determines that there is a defect in the object 15.

[0086] After step S51 is performed, the process proceeds to step S53. If it is determined in step S51 that the object 15 has no defects, the process proceeds to step S31. If it is determined that the object 15 has defects, the process proceeds to step S61.

[0087] In the method for monitoring a modeling process in the additive manufacturing method according to the third embodiment, in the first detection step (step S51), if the representative value Rv is less than a threshold value Th determined based on the reference value Ref, it is determined that there is no defect in the model 15, and if the representative value Rv is equal to or greater than the threshold value Th, it is determined that there is a defect in the model 15. According to the additive manufacturing method according to the third embodiment, the presence or absence of a defect in the model 15 can be detected by comparing the representative value Rv with the threshold value Th, thereby improving the accuracy of detecting the presence or absence of a defect in the model 15.

[0088] As a result of thorough investigations by the inventors, it was found that when single-layer modeling is performed multiple times, if the appearance frequency of the representative value Rv that is equal to or greater than the threshold value Th is low, the possibility of a defect in the object 15 is low, and when the appearance frequency of the representative value Rv that is equal to or greater than the threshold value Th is high, the possibility of a defect in the object 15 is high. Therefore, in the additive manufacturing method according to the third embodiment, if the appearance frequency Fr of the representative value Rv that is equal to or greater than the threshold value Th is less than a specified appearance frequency Fr1 when single-layer modeling is performed multiple times, it is possible to determine that the object 15 does not have a defect, and to determine that the object 15 has a defect if the appearance frequency Fr of the representative value Rv that is equal to or greater than the threshold value Th is equal to or greater than the specified appearance frequency Fr1.

[0089] That is, in step S51, the control unit 80 may compare the appearance frequency Fr with a specified appearance frequency Fr1, and if the appearance frequency Fr is less than the specified appearance frequency Fr1, determine that there is no defect in the object 15. In step S51, the control unit 80 may compare the appearance frequency Fr with the specified appearance frequency Fr1, and if the appearance frequency Fr is equal to or greater than the specified appearance frequency Fr1, determine that there is a defect in the object 15.

[0090] In the method for monitoring a modeling process in the additive manufacturing method according to the third embodiment, in the first detection step (step S51), if the appearance frequency Fr of the representative value Rv that is equal to or greater than the threshold value Th is less than a specified appearance frequency Fr1 when the modeling step (step S21) is performed multiple times, it may be determined that the model 15 does not have a defect, and if the appearance frequency Fr of the representative value that is equal to or greater than the threshold value Th is equal to or greater than the specified appearance frequency Fr1, it may be determined that the model 15 has a defect. This makes it possible to detect the presence or absence of a defect in the model 15 based on the appearance frequency Fr of the representative value Rv that is equal to or greater than the threshold value Th, thereby improving the accuracy of detecting the presence or absence of a defect in the model 15.

[0091] The process from step S61 onwards in FIG. 7 and the process from step S31 onwards in FIG. 7 are the same as the process from step S61 onwards in FIG. 6 and the process from step S31 onwards in FIG.

[0092] (Additive Manufacturing Method According to Fourth Embodiment) The additive manufacturing method according to the fourth embodiment will now be described. FIG. 8 is a flowchart showing the steps of the additive manufacturing method according to the fourth embodiment using the above-described three-dimensional additive manufacturing apparatus 1. In the following description, the same steps as those in the additive manufacturing methods according to the above-described embodiments will be denoted by the same reference numerals, and detailed description thereof may be omitted. The processes from step S11 to step S25 in FIG. 8 are the same as the processes from step S11 to step S25 in FIG. 2. If a negative judgment is made in step S25, the control unit 80 proceeds to step S31. If a positive judgment is made in step S25 in FIG. 8, the control unit 80 proceeds to step S61, where the control unit 80 determines whether the defect in the object 15 detected in step S23 is small. If a judgment is made in step S61 that the defect in the object 15 detected in step S23 is small, the control unit 80 proceeds to step S31 without performing steps S26, S27, and S29. If it is determined in step S61 that the defect in the model 15 detected in step S23 is not minute, the control unit 80 proceeds to step S26. The processing content of step S26 in the additive manufacturing method according to the fourth embodiment will be described below.

[0093] For example, when the surface of the object 15 is irradiated with laser light at an angle oblique to the normal direction of the surface of the object 15, if the surface roughness of the object 15 is relatively large, the scattered light from the surface of the object 15 will be affected by the surface roughness. Therefore, when acquiring the state of defects using a laser ultrasonic method, as with the flaw detection device 60 described above, it becomes difficult to accurately acquire the state of the defects. Furthermore, the surface roughness of the surface of the object 15 is generally relatively large. Therefore, there is a risk that the accuracy of the flaw detection device 60 in detecting the presence or absence of defects inside the object 15, as well as the position and size of the defects, will be reduced.

[0094] Therefore, in the additive manufacturing method according to the fourth embodiment, after a positive determination is made in step S25 and a negative determination is made in step S61, and before the flaw detector 60 inspects the object 15 in step S27 to obtain the state of the defect, the surface of the object 15 is processed by irradiating it with a beam in step S26 to reduce the surface roughness of the object 15 compared to before the beam irradiation. In other words, the additive manufacturing method according to the fourth embodiment includes step S26 in which, when a defect in the object 15 is detected based on information from the first detector 40, the surface of the object is processed by irradiating it with a beam.

[0095] In the additive manufacturing method according to the fourth embodiment, the beam irradiated onto the object 15 in step S26 is the light beam 71 irradiated by the light beam irradiation unit 21 of the light beam irradiation device 20. The irradiation conditions of the light beam 71, such as the output power of the light beam 71 irradiated onto the object 15 in step S26, are set to irradiation conditions suitable for processing the surface of the object 15 and making the surface roughness of the object 15 relatively small.

[0096] If a negative judgment is made in step S61 (if it is judged that the defect in the object 15 is not minute), the control unit 80 proceeds to step S26, and controls the light beam irradiation device 20 to irradiate the object 15 with the light beam 71 under irradiation conditions suitable for processing the surface of the object 15 and making the surface roughness of the object 15 relatively small. As a result, the surface of the object 15 is irradiated with the light beam 71, and the surface roughness of the object 15 becomes relatively small.

[0097] After step S26 is performed, the process proceeds to step S27. The processes from step S27 to step S33 in Fig. 8 are the same as the processes from step S27 to step S33 in Fig. 6 .

[0098] 8 , the flaw detector 60 inspects the object 15 to obtain the state of the defect, as in step S27. Therefore, in the additive manufacturing method according to the fourth embodiment, after a positive determination is made in step S33 and a negative determination is made in step S63, the surface of the object 15 is processed by irradiating it with a beam to reduce the surface roughness of the object 15 compared to before the beam irradiation, before the flaw detector 60 inspects the object 15 in step S35 to obtain the state of the defect. That is, the additive manufacturing method according to the fourth embodiment includes step S34 in which, when a defect in the object 15 (a defect on the top surface of the object 15) is detected based on information from the second detection device 50, the surface of the object 15 is processed by irradiating it with a beam.

[0099] In the additive manufacturing method according to the fourth embodiment, the beam irradiated onto the object 15 in step S34 is the light beam 71 irradiated by the light beam irradiation unit 21 of the light beam irradiation device 20. The irradiation conditions of the light beam 71, such as the output power of the light beam 71 irradiated onto the object 15 in step S34, are set to irradiation conditions suitable for processing the surface of the object 15 and making the surface roughness of the object 15 relatively small.

[0100] If a negative judgment is made in step S33, the control unit 80 proceeds to step S41. If a positive judgment is made in step S33, the control unit 80 proceeds to step S63, where it determines whether the defect on the top surface of the object 15 detected in step S31 is minor. If it is determined in step S63 that the defect on the top surface of the object 15 detected in step S31 is minor, the control unit 80 proceeds to step S41 without performing steps S34, S35, and S37. If it is determined in step S63 that the defect on the top surface of the object 15 detected in step S31 is not minor, the control unit 80 proceeds to step S34. In step S34, the control unit 80 controls the light beam irradiation device 20 to irradiate the object 15 with the light beam 71 under irradiation conditions suitable for processing the surface of the object 15 to make the surface roughness of the object 15 relatively small. As a result, the surface of the object 15 is irradiated with the light beam 71, and the surface roughness of the object 15 is relatively small.

[0101] The method for monitoring a building process in the additive manufacturing method according to the fourth embodiment may include, when a defect is detected in the first detection step (step S23, step S51) or the second detection step (step S31), a step of processing the surface of the object 15 by irradiating a beam (step S26, step S34), and a step of inspecting the object 15 whose surface has been processed in the step of processing the surface of the object 15 (step S26, step S34) to acquire the state of the defect (step S27, step S35). The additive manufacturing method according to the fourth embodiment makes it easier to ensure the accuracy of the inspection results, even when performing an inspection that is easily affected by the surface roughness of the object 15, such as with a flaw detection device 60 that performs flaw detection using a laser ultrasonic method. Furthermore, the additive manufacturing method according to the fourth embodiment processes the surface of the object 15 using the light beam 71 irradiated by the light beam irradiation unit 21 of the light beam irradiation device 20. This eliminates the need for additional equipment, and allows the surface of the object 15 to be processed relatively easily.

[0102] After step S34 is performed, the process proceeds to step S35. The process from step S35 onwards in Fig. 8 and the process from step S41 onwards in Fig. 8 are the same as the process from step S35 onwards in Fig. 6 and the process from step S41 onwards in Fig. 6.

[0103] In addition, if step S26 is performed prior to step S34, the defect is repaired in the subsequent step S29, so the beam in step S34 may be irradiated only to the repaired area and its surroundings in step S29.

[0104] (Additive Manufacturing Method According to Fifth Embodiment) The additive manufacturing method according to the fifth embodiment will be described below. The additive manufacturing method according to the fifth embodiment is different from the additive manufacturing method according to the fourth embodiment described above in that the sources of the beams that are irradiated onto the model 15 in steps S26 and S34 are different, but the rest is the same as the fourth embodiment described above.

[0105] In the additive manufacturing method according to the fourth embodiment described above, the beam irradiated onto the object 15 in steps S26 and S34 is the light beam 71 irradiated by the light beam irradiation unit 21 of the light beam irradiation device 20. In the additive manufacturing method according to the fifth embodiment, the beam irradiated onto the object 15 in steps S26 and S34 is laser light irradiated by the laser irradiation device 61 included in the flaw detection device 60. The irradiation conditions of the laser light irradiated by the laser irradiation device 61 in steps S26 and S34, such as the output power of the laser light, are set to irradiation conditions suitable for processing the surface of the object 15 and making the surface roughness of the object 15 relatively small.

[0106] According to the additive manufacturing method of the fifth embodiment, the surface of the molded object 15 is processed using laser light emitted by the laser irradiation device 61 provided in the flaw detection device 60, so no additional equipment is required and the surface of the molded object 15 can be processed relatively easily.

[0107] (Additive Manufacturing Method According to Sixth Embodiment) The additive manufacturing method according to the sixth embodiment will be described below. The additive manufacturing method according to the sixth embodiment is different from the additive manufacturing methods according to the fourth and fifth embodiments described above in that the sources of the beams that are irradiated onto the model 15 in steps S26 and S34 are different, but the rest of the additive manufacturing method is the same as the fourth and fifth embodiments described above.

[0108] FIG. 9 is a schematic diagram showing the overall configuration of a three-dimensional additive manufacturing apparatus 1A, which is an additive manufacturing apparatus to which the additive manufacturing method according to the sixth embodiment can be applied. The three-dimensional additive manufacturing apparatus 1A shown in FIG. 9 has a configuration similar to that of the three-dimensional additive manufacturing apparatus 1 shown in FIG. 1 , except for the addition of a surface processing irradiation device 90. The surface processing irradiation device 90 is an apparatus for irradiating the surface of the object 15 with a laser beam 95, and includes a laser beam irradiation unit 91 capable of irradiating the laser beam 95, and a laser beam control unit 92 that controls the laser beam irradiation unit 91. The laser beam control unit 92 is implemented by an electronic processing device such as a computer, and is configured to control the irradiation position of the laser beam 95 irradiated by the laser beam irradiation unit 91 based on information received from the control unit 80. Note that the irradiation conditions of the laser beam 95 irradiated by the laser beam irradiation unit 91 in steps S26 and S34, such as the output power of the laser beam, are set to irradiation conditions suitable for processing the surface of the object 15 and reducing the surface roughness of the object 15.

[0109] According to the additive manufacturing method of the sixth embodiment, the setting work associated with changing the irradiation conditions in the light beam irradiation unit 21 of the light beam irradiation device 20 and the laser irradiation device 61 of the flaw detection device 60 is not required.

[0110] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0111] The contents of the above-described embodiments can be understood as follows, for example. (1) A method for monitoring a manufacturing process according to at least one embodiment of the present disclosure includes: a step (step S21) of irradiating a layer 8 a of raw material powder 30 with an energy beam (light beam 71) to melt and solidify the raw material powder 30 in the layer 8 a to thereby manufacture a part of the object 15; a first detection step (steps S23 and S51) of detecting the presence or absence of a defect in the object 15 during the manufacturing step (step S21); and a second detection step (step S31) of measuring the surface shape of the object 15 after the manufacturing step (step S21) and detecting the presence or absence of a defect in the object 15 based on the surface shape of the object 15. The first detection step (step S23 and step S51) and the second detection step (step S31) are performed every time the manufacturing step (step S21) is performed.

[0112] According to the method (1) above, the first detection step (steps S23 and S51) is performed during the modeling step (step S21), thereby significantly shortening the inspection time. Furthermore, in the second detection step (step S31), the presence or absence of defects in the modeled object 15 is detected based on the surface shape of the modeled object 15, thereby enabling inspection to be completed in a relatively short time. Therefore, according to the method (1) above, the inspection time for the modeled object 15 can be reduced. Furthermore, according to the method (1) above, the first detection step (steps S23 and S51) and the second detection step (step S31) are performed every time the modeling step (step S21) is performed, thereby omitting non-destructive inspection after modeling of the modeled object 15 is completed, thereby reducing the inspection time and costs for the modeled object 15.

[0113] (2) In some embodiments, in the method described in (1) above, in the first detection step (step S23, step S51), it is preferable to detect the presence or absence of defects in the molded object 15 based on the light emission intensity of the light emitted from the molded object 15 when irradiated with an energy beam (light beam 71) in the molding step (step S21).

[0114] According to the method (2) above, the first detection step (steps S23, S51) can be performed relatively easily with a relatively simple device configuration while the molding step (step S21) is being performed, thereby suppressing the increase in the cost of the device for performing the first detection step (steps S23, S51).

[0115] (3) In some embodiments, in the method (2) above, in the first detection step (step S23), it is preferable to detect the presence or absence of defects in a forming layer below the topmost forming layer of the object 15 based on the light emission intensity.

[0116] According to the method (3) above, the presence or absence of defects in the forming layer below the topmost forming layer of the formed object 15 can be detected based on the light emission intensity of the light emitted from the formed object 15 when an energy beam (light beam 71) is irradiated onto the layer 8a of raw material powder 30.

[0117] (4) In some embodiments, in the method (2) or (3) above, in the first detection step (step S23), it is preferable to detect the presence or absence of defects in the topmost forming layer of the object 15 based on the light emission intensity.

[0118] According to the method (4) above, it is possible to detect defects in the shaped object 15 caused by undesired changes in the irradiation state of the energy beam (light beam 71), for example.

[0119] (5) In some embodiments, in the method of (2) above, in the first detection step (step S51), at least one of a plurality of measurement values ​​of the emission intensity obtained by measuring the emission intensity multiple times during one modeling step (step S21) may be selected in descending order of emission intensity and used as a representative value Rv of the emission intensity during one modeling step, and the presence or absence of a defect in the modeled object 15 may be detected based on the representative value Rv and a predetermined reference value Ref.

[0120] As a result of careful investigation by the inventors, it was found that there is a correlation between the comparison result between the representative value Rv and the reference value Ref and the presence or absence of a defect in the object 15. According to the method (5) above, the presence or absence of a defect in the object 15 can be detected based on the representative value Rv and the reference value Ref, and therefore the accuracy of detecting the presence or absence of a defect in the object 15 can be improved.

[0121] (6) In some embodiments, in the method of (5) above, in the first detection step (step S51), if the representative value Rv is less than a threshold value Th determined based on the reference value Ref, it is determined that the object 15 has no defect, and if the representative value Rv is equal to or greater than the threshold value Th, it is determined that the object 15 has a defect.

[0122] According to the method (6) above, the presence or absence of a defect in the object 15 can be detected by comparing the representative value Rv with the threshold value Th, and therefore the accuracy of detecting the presence or absence of a defect in the object 15 can be improved.

[0123] (7) In some embodiments, in the method of (6) above, in the first detection step (step S51), if the appearance frequency Fr of the representative value Rv that is equal to or greater than the threshold value Th when the modeling step (step S21) is performed multiple times is less than a specified appearance frequency Fr1, it may be determined that the model 15 has no defect, and if the appearance frequency Fr of the representative value that is equal to or greater than the threshold value Th is equal to or greater than the specified appearance frequency Fr1, it may be determined that the model 15 has a defect.

[0124] According to the method (7) above, the presence or absence of a defect in the object 15 can be detected based on the appearance frequency Fr of the representative value Rv that is equal to or greater than the threshold value Th, thereby improving the accuracy of detecting the presence or absence of a defect in the object 15.

[0125] (8) In some embodiments, in any of the methods (1) to (7) above, in the second detection step (step S31), the surface shape of the object 15 may be measured based on an image obtained by capturing an image of a pattern projected onto the surface of the object 15.

[0126] According to the method (8) above, the second detection step (step S31) can be carried out relatively easily with a relatively simple device configuration, so that the time required to carry out the second detection step (step S31) is relatively short, and the increase in the cost of the device for carrying out the second detection step (step S31) can be suppressed.

[0127] (9) In some embodiments, in any of the methods (1) to (8) above, when a defect is detected in the first detection step (step S23, step S51) or the second detection step (step S31), it is preferable to include a step (step S27, step S35) of inspecting the object 15 and acquiring the state of the defect.

[0128] According to the method (9) above, the state of the defect can be grasped in more detail.

[0129] (10) In some embodiments, in any of the methods (1) to (8) above, when a defect is detected in the first detection step (step S23, step S51) or the second detection step (step S31), the method may include a step of processing the surface of the object 15 by irradiating it with a beam (step S26, step S34), and a step of inspecting the object 15 whose surface has been processed in the step of processing the surface of the object 15 (step S26, step S34) to obtain the state of the defect (step S27, step S35).

[0130] According to the method (10) above, by irradiating the beam to process the surface of the object 15 so that the surface roughness 15 is reduced, it becomes easier to ensure the accuracy of the inspection results even when performing an inspection that is easily affected by the surface roughness of the surface of the object 15, for example.

[0131] (11) In some embodiments, in the method of (9) or (10) above, in the acquiring step (step S27, step S35), the state of the defect may be acquired by a laser ultrasonic method.

[0132] According to the method (11) above, the state of the defect can be grasped in more detail in a non-destructive manner.

[0133] (12) In some embodiments, the method of (11) above may include a step (step S29, step S37) of repairing the defect by irradiating an energy beam (light beam 71) under irradiation conditions set based on the state of the defect acquired in the acquisition step (step S27, step S35).

[0134] According to the method (12) above, defects can be repaired during the formation of the object 15, so that non-destructive testing after the formation of the object 15 is completed can be omitted, thereby reducing the time and costs required for inspecting the object 15.

[0135] (13) In some embodiments, in the method of (12) above, in the repairing step (step S29, step S37), if the defect depth De acquired in the acquiring step (step S27, step S35) is less than a specified depth De1, the defect may be repaired by irradiating the energy beam (light beam 71) with a first output P1. In the repairing step (step S29, step S37), if the defect depth De acquired in the acquiring step (step S27, step S35) is equal to or greater than the specified depth De1, the defect may be repaired by irradiating the energy beam (light beam 71) with a second output P2 that is greater than the first output P1 and that increases as the defect depth De increases.

[0136] According to the method (13) above, defects can be repaired with an output of the energy beam (light beam 71) that corresponds to the depth of the defect, thereby improving the reliability of defect repair. Note that even when the defect depth De is relatively shallow, the output of the irradiated energy beam (light beam 71) must be at a certain level or higher in order to re-melt the surface of the shaped object 15. According to the method (13) above, even when the defect depth De is less than the specified depth De1, the energy beam (light beam 71) is irradiated with the first output P1, thereby preventing the occurrence of a problem in which the surface of the shaped object 15 cannot be re-melted during defect repair.

[0137] (14) In some embodiments, in the method of (12) or (13) above, in the repairing steps (steps S29 and S37), if the maximum dimension dmax of the defect when viewed from above the object 15 is less than twice the beam width db of the energy beam (light beam 71), the defect may be repaired by irradiating the defect with the energy beam (light beam 71) without scanning. In the repairing steps (steps S29 and S37), if the maximum dimension dmax of the defect when viewed from above the object 15 is equal to or greater than twice the beam width db of the energy beam (light beam 71), the defect may be repaired by irradiating the defect with the energy beam (light beam 71) while scanning it.

[0138] According to the method (14) above, the energy beam (light beam 71) can be irradiated under irradiation conditions appropriate for the size of the defect, so that when repairing a relatively small defect, the object 15 can be prevented from being heated more than necessary, and when repairing a relatively large defect, heating necessary for repairing the defect can be applied, thereby improving the quality of the object 15.

[0139] (15) In some embodiments, in any of the methods (1) to (14) above, after performing the step of forming the layer 8a (step S11) and before performing the step of shaping (step S21), it is preferable to include a step (step S13) of measuring the surface shape of the layer 8a and detecting the presence or absence of defects in the layer 8a based on the surface shape of the layer 8a.

[0140] According to the method (15) above, it is possible to grasp the quality of the state of the layer 8a formed by laying the raw material powder 30.

[0141] (16) In some embodiments, the method of (15) above may include a step (step S11) of supplying raw material powder 30 to form a new layer 8a of raw material powder 30 when the presence of a defect in layer 8a is detected in the detection step (step S13).

[0142] According to the method (16) above, the soundness of the layer 8a formed by spreading the raw material powder 30 can be improved.

[0143] (17) An additive manufacturing apparatus (three-dimensional additive manufacturing apparatus 1) according to at least one embodiment of the present disclosure includes a powder bed formation unit 5 having a base plate 2 on which a layer 8 a is formed using supplied raw material powder 30, an energy beam irradiation unit (light beam irradiation device 20) capable of irradiating the layer 8 a with an energy beam (light beam 71), a first detection device 40 configured to detect the presence or absence of defects in the object 15 during irradiation with the energy beam (light beam 71), and a second detection device 50 configured to measure the surface shape of the object 15 after irradiation with the energy beam (light beam 71) and detect the presence or absence of defects in the object 15 based on the surface shape of the object 15. The powder bed formation unit 5 is configured to detect the presence or absence of defects in the object 15 using the first detection device 40 and to detect the presence or absence of defects in the object 15 using the second detection device 50, and then supply raw material powder 30 to form the layer 8 a of the raw material powder 30.

[0144] According to the configuration (17) above, the presence or absence of defects in the object 15 is detected while the energy beam (light beam 71) for modeling is being irradiated, thereby significantly shortening the inspection time. Furthermore, the presence or absence of defects in the object 15 can be detected by the second detection device 50 based on the surface shape of the object 15, allowing inspection to be performed in a relatively short time. Therefore, according to the configuration (17) above, the inspection time for the object 15 can be reduced. Furthermore, according to the configuration (17) above, the presence or absence of defects can be detected by the first detection device 40 and the second detection device 50 each time each layer 8a is modeled, thereby omitting non-destructive testing after modeling of the object 15 is completed, thereby reducing the inspection time and costs for the object 15.

[0145] (18) An additive manufacturing method according to at least one embodiment of the present disclosure includes a step of detecting the presence or absence of defects in the object 15 by using any of the methods for monitoring the manufacturing process described above in (1) to (16).

[0146] According to the method (18) above, it is possible to obtain a high-quality object 15 while suppressing the time and cost required for inspecting the object 15.

[0147] REFERENCE SIGNS LIST 1, 1A Three-dimensional additive manufacturing apparatus (additive manufacturing apparatus) 2 Base plate 2a Drive cylinder 4 Cylinder 5 Powder bed forming section 6 Beam splitter 8 Powder bed 8a Layer 9 Chamber 9a Window section 8a Layer 10 Powder laying section 15 Modeled object 20 Light beam irradiation device 21 Light beam irradiation section 22 Light beam control section 30 Raw material powder 31 Storage section 40 First detection device 41 Light detection section 42 Light emission monitor control section 50 Second detection device 51 Projection section 52 Imaging section 53 Concave / convex detection section 60 Flaw detection device 61 Laser irradiation device 62 Laser interferometer 63 Flaw detection control section 71 Light beam 80 Control section 90 Surface processing irradiation device 91 Laser light irradiation section 92 Laser light control section 95 Laser light

Claims

1. forming a part of a model by irradiating a layer of raw material powder with an energy beam to melt and solidify the raw material powder in the layer; a first detection step of detecting the presence or absence of a defect in the object during the modeling step; a second detection step of measuring a surface shape of the object after the forming step is performed, and detecting the presence or absence of a defect in the object based on the surface shape of the object; Equipped with In the first detection step, the presence or absence of a defect in a modeling layer below a topmost modeling layer of the object is detected based on an emission intensity of light emitted from the object when the energy beam is irradiated in the modeling step, and the presence or absence of a defect in the topmost modeling layer of the object is detected. the first detection step and the second detection step are performed every time the modeling step is performed; How to monitor the build process.

2. in the first detection step, among a plurality of measurement values ​​of the emission intensity obtained by measuring the emission intensity a plurality of times during one execution of the modeling step, at least one of the measurement values ​​in descending order of the emission intensity is set as a representative value of the emission intensity during one execution of the modeling step, and the presence or absence of the defect or the malfunction is detected based on the representative value and a predetermined reference value. The method of claim 1 .

3. In the first detection step, when the representative value is less than a threshold value determined based on the reference value, it is determined that the defect or the malfunction does not exist, and when the representative value is equal to or greater than the threshold value, it is determined that the defect or the malfunction exists. The method of claim 2 .

4. In the first detection step, when the occurrence frequency of the representative value that is equal to or greater than the threshold value is less than a specified occurrence frequency when the modeling step is performed a plurality of times, it is determined that the defect and the malfunction are not present, and when the occurrence frequency of the representative value that is equal to or greater than the threshold value is equal to or greater than the specified occurrence frequency, it is determined that the defect or the malfunction is present. The method of claim 3 .

5. In the second detection step, a surface shape of the object is measured based on an image obtained by capturing an image of a pattern projected onto a surface of the object. A method for monitoring a modeling process according to any one of the preceding claims.

6. a step of inspecting the object to obtain a state of the defect or the malfunction when the defect or the malfunction is detected in the first detection step or the second detection step; Equipped A method for monitoring a modeling process according to any one of the preceding claims.

7. a step of processing a surface of the object by irradiating a beam when the defect or the malfunction is detected in the first detection step or the second detection step; a step of inspecting the object whose surface has been processed in the step of processing the surface of the object to obtain a state of the defect or the malfunction; Equipped A method for monitoring a modeling process according to any one of the preceding claims.

8. In the acquiring step, the state of the defect or the malfunction is acquired by a laser ultrasonic method. The method of claim 6 .

9. a step of irradiating the energy beam under irradiation conditions set based on the state of the defect or the malfunction acquired in the acquiring step, thereby repairing the defect or the malfunction; Equipped with The method of claim 8 .

10. In the repairing step, If the depth of the defect or the fault acquired in the acquiring step is less than a specified depth, the energy beam is irradiated at a first output to repair the defect or the fault; If the depth of the defect or the malfunction acquired in the acquiring step is equal to or greater than a prescribed depth, the energy beam is irradiated with a second output that is greater than the first output and that increases as the depth of the defect or the malfunction increases, thereby repairing the defect or the malfunction. The method of claim 9 .

11. In the repairing step, If the maximum dimension of the defect or the defect when viewed from above the object is less than twice the beam width of the energy beam, the defect or the defect is repaired by irradiating the energy beam without scanning it; If the maximum dimension of the defect or the fault when viewed from above the object is equal to or greater than twice the beam width of the energy beam, the defect or the fault is repaired by irradiating the energy beam while scanning it. The method of claim 9 .

12. providing the raw material powder to form the layer; a step of measuring a surface shape of the layer after performing the step of forming the layer and before performing the step of modeling, and detecting the presence or absence of a defect in the layer based on the surface shape of the layer; Equipped A method for monitoring a modeling process according to any one of the preceding claims.

13. supplying the raw material powder to form a new layer of the raw material powder when the detecting step detects that the layer has a defect; Equipped The method of claim 12 .

14. a powder bed forming section having a base plate on which a layer is formed by the supplied raw material powder; an energy beam irradiation unit capable of irradiating the layer with an energy beam; a first detection device configured to detect the presence or absence of a defect in the object during irradiation of the energy beam; a second detection device configured to measure a surface shape of the object after the energy beam is irradiated, and to detect the presence or absence of a defect in the object based on the surface shape of the object; Equipped with the first detection device is configured to detect, during irradiation of the energy beam, the presence or absence of a defect in a modeling layer below a topmost modeling layer of the object, and the presence or absence of a defect in the modeling layer on the topmost surface of the object; The powder bed formation unit is configured to detect the presence or absence of defects in a modeling layer below the topmost modeling layer of the modeled object and the presence or absence of a defect in the modeling layer on the topmost surface of the modeled object with the first detection device, and to supply the raw material powder to form a layer of the raw material powder after detecting the presence or absence of a defect in the modeled object with the second detection device. Additive manufacturing equipment.

15. 5. A step of detecting the presence or absence of the defect or the malfunction by the method for monitoring a molding process according to any one of claims 1 to 4; An additive manufacturing method comprising: