Three-dimensional additive manufacturing apparatus and method for determining manufacturing defects.

Abstract

This system appropriately detects molding defects caused by a blockage in one of the multiple injection nozzles, which increases the amount of powder ejected from the other nozzles. [Solution] A three-dimensional additive manufacturing apparatus is provided, comprising a stacking head that melts powder onto a base to create a laminate, a moving unit that moves the stacking head in the manufacturing direction MD relative to the base, and a determination unit that determines whether or not a manufacturing abnormality has occurred in the laminate. The stacking head has a plurality of spray nozzles that spray powder toward the manufacturing area on the base, a powder supply unit that supplies powder to the plurality of spray nozzles, a light irradiation unit that irradiates the manufacturing area with a light beam to melt the powder and create a laminate on the base, and an imaging unit that captures an image of the manufacturing area including the molten pool M formed by the molten powder. The determination unit determines whether or not a manufacturing abnormality has occurred based on the shape of the molten pool M in the determination region JA downstream of the manufacturing direction MD in the image captured by the imaging unit.

Description

Technical Field

[0001] The present disclosure relates to a three-dimensional lamination apparatus and a modeling abnormality determination method.

Background Art

[0002] AM (Additive Manufacturing) products are manufactured by laminating materials. For quality assurance of AM products, non-destructive inspections such as X-ray inspection and ultrasonic flaw inspection may be performed after the AM product is manufactured, but this may lead to an increase in manufacturing cost.

[0003] Patent Document 1 discloses that in order to avoid an increase in manufacturing cost due to non-destructive inspection, when manufacturing an AM product by the DED (Directed Energy Deposition) method, an image of a modeling portion including a molten pool formed of molten powder is captured, and it is determined whether the modeling of the laminate is abnormal using a learning model obtained by performing machine learning on the correspondence relationship of abnormality types in the images.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When manufacturing an AM product by the DED method, powder is jetted from a plurality of jet nozzles toward a modeling portion. If clogging occurs in any of the plurality of jet nozzles, the amount of powder jetted from the clogged jet nozzle decreases, and the amount of powder jetted from the other jet nozzles increases. If the increase amount of the powder jetted from the jet nozzles is excessive relative to the energy of the light beam for melting the powder, part of the increased powder may not be melted, leading to occurrence of a modeling abnormality.

[0006] Patent Document 1 discloses a method for determining whether the fabrication of a laminate is abnormal by using a learning model that has been pre-trained to process images corresponding to multiple types of abnormalities, such as alignment anomalies. However, Patent Document 1 does not disclose how to detect fabrication abnormalities caused by an increase in powder ejection from other nozzles due to clogging of some nozzles or by an increase in powder.

[0007] This disclosure has been made in view of the above circumstances and aims to provide a three-dimensional additive manufacturing apparatus and a method for determining manufacturing defects that can appropriately determine manufacturing defects caused by a blockage in one of the multiple injection nozzles, which increases the amount of powder ejected from the other injection nozzles. [Means for solving the problem]

[0008] A three-dimensional additive manufacturing apparatus according to one aspect of the present disclosure comprises a manufacturing unit that melts powder onto an object to be laminated to form a laminate, a moving unit that moves the manufacturing unit in the manufacturing direction relative to the object to be laminated, and a determination unit that determines whether or not a manufacturing abnormality has occurred in the laminate. The manufacturing unit comprises a plurality of spray nozzles that spray the powder toward the manufacturing location of the object to be laminated, a powder supply unit that supplies the powder to the plurality of spray nozzles so that the amount of powder sprayed from the plurality of spray nozzles does not become biased by more than a predetermined proportion, a light irradiation unit that irradiates the manufacturing location with a light beam to melt the powder and form a laminate on the object to be laminated, and an imaging unit that captures an image of the manufacturing location including a molten region formed by the molten powder. The determination unit determines whether or not a manufacturing abnormality has occurred based on the shape of the molten region in the determination region downstream of the manufacturing direction in the image captured by the imaging unit.

[0009] A method for determining a manufacturing anomaly according to one aspect of the present disclosure is a method for determining a manufacturing anomaly in a three-dimensional additive manufacturing apparatus that melts powder onto an object to be laminated to form a laminate, wherein the three-dimensional additive manufacturing apparatus comprises a manufacturing unit that melts the powder onto the object to be laminated to form the laminate, and a moving unit that moves the manufacturing unit in the manufacturing direction relative to the object to be laminated, wherein the manufacturing unit comprises a plurality of spray nozzles that spray the powder toward the manufacturing location of the object to be laminated, a powder supply unit that supplies the powder to the plurality of spray nozzles so that the amount of powder sprayed from the plurality of spray nozzles does not become biased by more than a predetermined proportion, and a light irradiation unit that irradiates the manufacturing location with a light beam to melt the powder and form a laminate on the object to be laminated, and comprises an imaging step of capturing an image of the manufacturing location including a molten region formed by the molten powder, and a determination step of determining whether a manufacturing anomaly has occurred in the laminate based on the shape of the molten region in a determination region downstream of the manufacturing direction of the image captured by the imaging step. [Effects of the Invention]

[0010] According to this disclosure, it is possible to provide a three-dimensional additive manufacturing apparatus and a method for determining manufacturing defects that can appropriately determine manufacturing defects caused by a blockage in one of the multiple injection nozzles, which increases the amount of powder ejected from the other injection nozzles. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a three-dimensional stacking apparatus according to one embodiment of the present disclosure. [Figure 2] Figure 1 is a schematic diagram of the stacking head shown. [Figure 3] Figure 2 is a cross-sectional view of the stacking head taken along the EE arrow. [Figure 4] This is a flowchart showing a method for determining molding defects performed by a three-dimensional additive manufacturing apparatus according to one embodiment of the present disclosure. [Figure 5] This is a diagram showing an example of a reference image. [Figure 6] Figure 5 shows the analysis results of the reference image. [Figure 7] This figure shows an example of an image used for judgment. [Figure 8] Figure 7 shows the analysis results of the image used for judgment. [Figure 9] This figure shows a first modified example of the analysis results of the judgment image shown in Figure 7. [Figure 10] This figure shows a second modified example of the analysis results of the judgment image shown in Figure 7. [Modes for carrying out the invention]

[0012] Hereinafter, a three-dimensional stacking apparatus 1 according to one embodiment of the present disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram of the three-dimensional stacking apparatus 1 according to one embodiment of the present disclosure. Figure 2 is a schematic diagram of the stacking head 18 shown in Figure 1.

[0013] In this embodiment, one direction in the horizontal plane is defined as direction X, the direction perpendicular to direction X in the horizontal plane is defined as direction Y, and the direction perpendicular to both direction X and direction Y (vertical direction) is defined as direction Z. Furthermore, one of the directions along direction Z is defined as direction Z1, and the other direction along direction Z, i.e., the direction opposite to direction Z1, is defined as direction Z2. In this embodiment, direction Z1 is the direction that points vertically upward, and direction Z2 is the direction that points vertically downward.

[0014] (Overall configuration of a three-dimensional stacking apparatus) As shown in Figure 1, the three-dimensional additive manufacturing apparatus 1 comprises a base unit 10, a base movement unit 12, a base unit 14, a base unit 16, a stacking head (molding unit) 18, a head movement unit 20, a determination unit 22, a notification unit 24, and a control unit 26, all located within the three-dimensional stacking chamber R. The control unit 26 may be located outside the three-dimensional stacking chamber R.

[0015] The three-dimensional lamination apparatus 1 is an apparatus for forming a laminate A, which is a three-dimensional shaped object, on a base portion 14 that is a lamination target. The base portion 14 is a member that serves as a base on which the laminate A is formed. The base portion 14 of the present embodiment is a plate-shaped member. Note that the base portion 14 may be a member of another shape such as a cylindrical member or a curved surface-shaped member instead of a plate-shaped member. The base portion 14 is a member that is separate from the laminate A and serves as the base of the laminate A, but may be a member that is combined with the laminate A to become a part of the laminate A.

[0016] (Base unit, base moving unit) The base unit 10 is a stand that supports the base moving unit 12, the base portion 14, and the like. The base moving unit 12 is provided on the base unit 10 and supports the base portion 14. The base moving unit 12 is a mechanism that moves the base portion 14 under the control of the control unit 26. The base moving unit 12 includes a first moving unit 12A, a second moving unit 12B, and a rotating unit 12C. The first moving unit 12A is a mechanism that moves the base portion 14 in a first direction along the horizontal direction (perpendicular to the vertical direction). In the present embodiment, the first moving unit 12A moves the base portion 14 along the Y direction. More specifically, in the present embodiment, the second moving unit 12B, the rotating unit 12C, and the base portion 14 are disposed on the first moving unit 12A, and the first moving unit 12A moves the second moving unit 12B, the rotating unit 12C, and the base portion 14 along the Y direction.

[0017] The second moving unit 12B is a mechanism that moves the base portion 14 in a second direction along the horizontal direction (perpendicular to the vertical direction), and the second direction is a direction perpendicular to the first direction. In the present embodiment, the second moving unit 12B moves the base portion 14 along the X direction. More specifically, in the present embodiment, the rotating unit 12C and the base portion 14 are disposed on the second moving unit 12B, and the second moving unit 12B moves the rotating unit 12C and the base portion 14 along the X direction. In the present embodiment, the first moving unit 12A and the second moving unit 12B are sliders that move the base portion 14 mounted thereon, but may be mechanisms other than sliders.

[0018] The rotating part 12C is a rotary table on which the base part 14 is placed. The rotating part 12C rotates the base part 14 located on top of it by rotating about at least one axis of rotation. In this embodiment, the rotating part 12C rotates the base part 14 with three mutually orthogonal axes of rotation as its centers of rotation.

[0019] Thus, the base moving section 12 moves the base section 14 along directions X and Y using the first moving section 12A and the second moving section 12B, and rotates the base section 14 around three rotation axes using the rotating section 12C. In other words, the base moving section 12 is a five-axis moving mechanism that moves the base section 14 along two axes and rotates it around three rotation axes. However, the base moving section 12 is not limited to a five-axis moving mechanism; for example, it may be a two-axis moving mechanism that moves the base section 14 along directions X and Y.

[0020] (base) The base portion 16 is a base provided within the three-dimensional stacking chamber R, and in this embodiment, the head moving portion 20 is provided.

[0021] (Head movement section) The head moving unit 20 moves the stacking head 18 along the direction Z. In this embodiment, the head moving unit 20 is attached to the base unit 16. The head moving unit 20 moves the stacking head 18 along the direction Z. In this embodiment, the head moving unit 20 is a slider that moves the stacking head 18, but it may be a mechanism other than a slider. Also, the head moving unit 20 is not limited to being attached to the base unit 16, and the mounting position is arbitrary.

[0022] Thus, in this embodiment, the base unit 12 moves the base unit 14 (laminated body A) in the X and Y directions, thereby changing the position of the laminating head 18 relative to the laminated body A in the X and Y directions. Furthermore, in this embodiment, the head unit 20 moves the laminating head 18 in the Z direction, thereby changing the position of the laminating head 18 relative to the laminated body A in the Z direction.

[0023] However, the method of changing the position of the lamination head 18 relative to the laminate A is not limited to this. For example, the lamination head 18 may be moved in at least one direction of the X and Y directions, or the laminate A may be moved in the Z direction. In other words, the three-dimensional lamination apparatus 1 may change the position of the lamination head 18 relative to the laminate A by moving the laminate A, or by moving the lamination head 18, or by moving both the laminate A and the lamination head 18.

[0024] In the three-dimensional additive manufacturing apparatus 1, the base moving unit 12 and the head moving unit 20 move the additive manufacturing head 18 relative to the base unit 14, thereby creating a stacked body A on the base unit 14. With the base unit 14 as the reference point, the direction in which the additive manufacturing head 18 moves on the horizontal plane (XY plane) is the manufacturing direction for creating the stacked body A.

[0025] (Stacked head) The stacking head 18 is a device that melts powder onto the base portion 14, which is the object to be stacked, to form a stacked body A. The stacking head 18 is located on the Z1 side of the base portion 14, that is, vertically above the base portion 14. The stacking head 18 irradiates a light beam L from the light beam irradiation port 18Ga toward the base portion 14 and sprays powder P from the spray ports 18Aa and 18Ba toward the base portion 14, thereby forming a stacked body A on the base portion 14. In other words, the three-dimensional stacking apparatus 1 according to this embodiment is a deposition-type three-dimensional stacking apparatus equipped with a stacking head 18.

[0026] Figure 2 is a schematic diagram of the stacking head 18 according to this embodiment. Figure 3 is a cross-sectional view of the stacking head 18 shown in Figure 2, taken along the EE arrow. As shown in Figures 1 and 2, the stacking head 18 includes a plurality of injection nozzles 18A, 18B, and 18C, a powder supply unit 18D, a light irradiation unit 18E, and an imaging unit 18F.

[0027] Multiple injection nozzles 18A, 18B, and 18C inject powder P towards the build area on the base 14. As shown in Figure 3, the injection nozzles 18A, 18B, and 18C are through-holes formed at 120-degree intervals around an axis Z that passes through the center of the main body 18a of the layering head 18. Powder P is supplied to the injection nozzles 18A, 18B, and 18C from the powder supply unit 18D. Powder is injected from the injection port 18Aa of injection nozzle 18A towards the build area on the base 14, from the injection port 18Ba of injection nozzle 18B towards the build area on the base 14, and from the injection port (not shown) of injection nozzle 18C towards the build area on the base 14.

[0028] As shown in Figure 1, the powder supply unit 18D is a device that supplies powder P to multiple injection nozzles 18A, 18B, and 18C. The powder supply unit 18D distributes the powder, which is guided from the powder supply source 2 via the supply line 3, to the supply lines 18Da, 18Db, and 18Dc. The powder distributed by the powder supply unit 18D to the supply line 18Da is supplied to the injection nozzle 18A and injected from the injection port 18Aa. The powder distributed by the powder supply unit 18D to the supply line 18Db is supplied to the injection nozzle 18B and injected from the injection port 18Ba. The powder distributed by the powder supply unit 18D to the supply line 18Dc is supplied to the injection nozzle 18C and injected from the injection port (not shown).

[0029] The powder supply unit 18D supplies powder to the multiple injection nozzles 18A, 18B, and 18C in such a way that the amount of powder injected from each nozzle does not become uneven by more than a predetermined percentage. The predetermined percentage is, for example, 5% or less, and it is preferable to make it as close to 0% as possible.

[0030] The light irradiation unit 18E is a device that irradiates the area to be fabricated with a light beam L to melt the powder and fabricate a laminated body A on the base unit 14. The laminated head 18 has a light beam irradiation port 18Ga opening at its end 18b on the Z2 side, which communicates with the beam path 18G. In other words, the light beam irradiation port 18Ga is an opening on the Z2 side of the beam path 18G. An optical element 18Gb and protective glass 18Gc are provided within the beam path 18G.

[0031] The optical element 18Gb includes, for example, a collimating lens that collimates the light beam L and a focusing lens that focuses the collimated light beam L. The protective glass 18Gc is provided on the end 18b side of the optical element 18Gb and is a cover glass that protects the inside of the stacked head 18. The light beam L output from the light irradiation unit 18E is reflected by mirrors 18Ea and 18Eb provided between the light irradiation unit 18E and the beam path 18G and introduced into the beam path 18G.

[0032] The light beam L travels along the beam path 18G in the Z2 direction, is focused by the optical element 18Gb, passes through the protective glass 18Gc, and is emitted from the light beam irradiation port 18Ga to the outside of the stacked head 18. The light beam L emitted from the light beam irradiation port 18Ga travels in the Z2 direction and irradiates the base portion 14.

[0033] Here, the powder P is ejected toward the base portion 14 with a predetermined spot diameter, and the light beam L is irradiated toward the base portion 14 with a predetermined spot diameter. The powder P melts due to the heat of the light beam L and the heat of the laminate A heated by the irradiation of the light beam L, forming a molten pool (molten region) M. The molten pool M can be said to contain at least one of the molten powder P and the molten laminate A. As the base portion 14 moves relative to the lamination head 18, the position to which the light beam L is irradiated changes.

[0034] Therefore, the areas where the light beam L was irradiated and formed the molten pool M cool and solidify when the light beam L is no longer irradiated, forming a bead B. By stacking these beads B in a three-dimensional manner, the laminate A is formed. Hereinafter, the areas on the base portion 14 where the light beam L is irradiated and powder P is sprayed, that is, the areas where beads B are formed, will be referred to as the fabricated areas. The fabricated areas include at least the parts where the molten pool M is formed, and more precisely, they include the molten pool M and the beads B surrounding the molten pool M.

[0035] In this embodiment, the light beam L is laser light, but it is not limited to laser light; for example, it may be an electron beam or the like. Also, in this embodiment, the powder P is metal powder, but other powders such as resin powder can also be used.

[0036] (Imaging Department) In this embodiment, the imaging unit 18F is an infrared camera that captures an image of infrared light I. The imaging unit 18F is, for example, an InGaAs camera. The imaging unit 18F is attached to the stacking head 18 and its position is fixed relative to the stacking head 18. As shown in Figure 2, the imaging unit 18F is located on the Z1 side of the stacking head 18, and the optical axis of the imaging unit 18F is coaxial with the optical axis of the light beam L in the beam path 18G. Infrared light I is emitted from the fabrication area (molten pool M and the surrounding stacked body A). The infrared light I travels from the light beam irradiation port 18Ga through the beam path 18G in the Z1 direction.

[0037] Mirror 18Eb reflects the light beam L but transmits infrared light I, so the infrared light I passes through mirror 18Eb and enters the imaging unit 18F. The imaging unit 18F captures an image of the fabricated area, including the molten pool M, by capturing an image of this infrared light I. The wavelength of the infrared light I detected by the imaging unit 18F is, for example, 0.75 μm to 1000 μm, and more preferably, near-infrared light with a wavelength of approximately 0.75 μm to 1.4 μm. The position where the imaging unit 18F is provided is not limited to the position described above, but may be any position. Also, the imaging unit 18F is not limited to an infrared camera.

[0038] As shown in Figure 2, some of the infrared light I from the fabrication area (molten pool M and the surrounding laminate A) travels straight in the Z1 direction within the beam path 18G and reaches the imaging unit 18F, while other portions of the infrared light I are reflected by the inner surface 18Gd of the beam path 18G and incident on the imaging unit 18F. The imaging unit 18F also captures an image of the infrared light I that has been reflected by the inner surface 18Gd and reached the imaging unit 18F.

[0039] In other words, the imaging unit 18F captures images of infrared light I that travels straight through the light beam irradiation port 18Ga in the Z1 direction, i.e., the image of infrared light I that reaches the imaging unit 18F without being reflected by the inner surface 18Gd, and the image of infrared light I that reaches the imaging unit 18F after being reflected by the inner surface 18Gd. The image of infrared light I that reaches the imaging unit 18F without being reflected by the inner surface 18Gd is an image of the region inside the outer circumference of the light beam irradiation port 18Ga, and can be said to be an image of the fabricated area (molten pool M and the surrounding laminate A). Also, the image of infrared light I that reaches the imaging unit 18F after being reflected by the inner surface 18Gd can be said to be an image of the inner surface 18Gd.

[0040] (Judgment Department) The determination unit 22 is a device that determines whether a printing abnormality has occurred in the printing operation of the stacked body A by the stacking head 18, based on the image captured by the imaging unit 18F. The determination unit 22 determines whether a printing abnormality has occurred in the stacked body A by the stacking head 18 by comparing a determination image, which is an image of the printing area captured by the imaging unit 18F during the printing of the stacked body A, with a reference image that has been captured in advance.

[0041] (News Department) The notification unit 24 is a device that notifies the operator of the three-dimensional additive manufacturing apparatus 1 of information such as identifying the injection nozzle corresponding to the molding abnormality among the multiple injection nozzles 18A, 18B, and 18C, and information indicating that a molding abnormality has occurred.

[0042] (Control Unit) The control unit 26 is a device that controls each part of the three-dimensional additive manufacturing apparatus 1, in this case it is a computer. The control unit 26 controls the additive manufacturing head 18, causing powder P to be ejected from the additive manufacturing head 18 while irradiating it with a light beam L, and moves the position of the base part 14 (additive body A) relative to the additive manufacturing head 18 at a predetermined feed rate, thereby creating the additive body A.

[0043] (Determination method for molding abnormalities) Next, the method for determining a manufacturing anomaly performed by the three-dimensional additive manufacturing apparatus 1 of this embodiment will be described with reference to the drawings. Figure 4 is a flowchart showing the method for determining a manufacturing anomaly performed by the three-dimensional additive manufacturing apparatus 1 according to one embodiment of the present disclosure.

[0044] In step S101, the control unit 26 controls the stacking head 18 and the base moving unit 12 to start the stacking operation of the stacked body A by the stacking head 18. The control unit 26 moves the stacking head 18 relative to the base unit 14 in the stacking direction and forms a bead B on the base unit 14 along the stacking direction, which becomes part of the stacked body A.

[0045] In step S102, the control unit 26 controls the imaging unit 18F to acquire a reference image that will serve as a reference for determining whether a printing abnormality has occurred in the printing operation of the laminated body A by the stacking head 18. Figure 5 shows an example of a reference image.

[0046] In step S103, the determination unit 22 performs an analysis process to analyze the reference image acquired by the imaging unit 18F in step S102. As shown in Figure 6, the determination unit 22 extracts the fabrication area FA corresponding to the fabrication location (molten pool M and the surrounding laminate A) from the reference image. For example, the determination unit 22 extracts a predetermined circular area within the reference image as the fabrication area FA.

[0047] Next, the determination unit 22 extracts boundary lines BL based on the brightness values ​​of each pixel in the build area FA. For example, the determination unit 22 extracts boundary lines BL as the boundary between an area having a brightness value higher than a predetermined determination brightness value and an area having a brightness value lower than a predetermined determination brightness value. The determination unit 22 also extracts from the build area FA a roughly semi-circular low-brightness area LA with a lower brightness value on either side of the boundary line BL, and a roughly circular molten pool M with a higher brightness value on either side of the boundary line BL. The determination unit 22 also identifies the centroid position CG of the low-brightness area LA.

[0048] Figure 6 shows the axis Z, which is the position where the light beam L is irradiated, and the injection region IAa, from which powder is ejected from injection nozzle 18A, injection region IAb, from which powder is ejected from injection nozzle 18B, and injection region IAc, from which powder is ejected from injection nozzle 18C. The powder ejected into injection regions IAa, IAb, and IAc is melted by the energy of the light beam L passing through axis Z, forming a molten pool M.

[0049] The reason the brightness value of the low-brightness region LA is lower than the brightness value of the molten pool M is that the low-brightness region LA is located downstream of the build direction of the stacking head 18, and is therefore not irradiated by the light beam L. The determination unit 22 identifies the direction from the position through which the axis Z passes towards the centroid position CG as the build direction MD of the stacking head 18, using the straight line L1 connecting the centroid position CG of the low-brightness region LA and the position through which the axis Z passes.

[0050] The determination unit 22 identifies the intersection CP where the straight line L1 and the boundary line BL intersect, and identifies P1, P2, and P3 at regular intervals from intersection CP toward axis Z. The determination unit 22 identifies the points at P1, P2, and P3 where the line perpendicular to the straight line L1 intersects with the boundary line BL as P1a, P1b, P2a, P2b, P3a, and P3b, respectively.

[0051] The determination unit 22 calculates an approximate circle from P1a, P1b, P2a, P2b, P3a, and P3b, for example using the least squares method, and identifies the center C1 of the approximate circle and the semicircular determination region JA (area enclosed by a dotted line) on the intersection CP side of the approximate circle. The determination region JA is a roughly semicircular area downstream in the molding direction MD of the circular region that approximates the boundary line BL between the molten pool M, which has a brightness value higher than the determination brightness value, and the low brightness region LA, which has a brightness value lower than the determination brightness value.

[0052] In step S104, the control unit 26 controls the imaging unit 18F to acquire a determination image for determining whether a printing abnormality has occurred in the printing operation of the laminated body A by the stacking head 18. Figure 7 shows an example of a determination image.

[0053] In step S105, the determination unit 22 performs an analysis process to analyze the determination image acquired by the imaging unit 18F in step S104. As shown in Figure 8, the determination unit 22 extracts the fabrication area FA corresponding to the fabrication location (molten pool M and the surrounding laminate A) from the determination image. For example, the determination unit 22 extracts a predetermined circular area within the reference image as the fabrication area FA.

[0054] Next, the determination unit 22 extracts boundary lines BL in the build area FA where the difference in brightness value between adjacent areas is equal to or greater than a predetermined brightness threshold. The determination unit 22 also extracts from the build area FA a roughly semi-circular low-brightness region LA with a low brightness value and a roughly circular molten pool M with a high brightness value, both on either side of the boundary line BL.

[0055] In step S106, the determination unit 22 determines whether a printing abnormality has occurred in the printing operation of the laminated body A by the lamination head 18, based on the shape of the molten pool M in the determination area JA identified in step S103. If the determination unit 22 determines that there is a printing abnormality, it proceeds to step S107; if it determines that there is no printing abnormality, it proceeds to step S108.

[0056] The determination unit 22 determines that a molding abnormality has occurred if the proportion of low-luminance regions LA (region LA1 with hatching in Figure 8) having a luminance value lower than the determination luminance value referenced to extract the boundary line BL in the determination region JA is a predetermined proportion (for example, 18%) or more.

[0057] In step S107, the control unit 26 determines whether to terminate the printing operation of the laminated body A by the stacking head 18, which was started in step S101. If it is YES, it terminates the process in this flowchart; otherwise, it repeats the process from step S104 onwards.

[0058] In step S108, the determination unit 22 increments an abnormality determination counter, which is a value stored internally within the determination unit 22. The abnormality determination counter is 0 at the start of this flowchart, and its count value increases by 1 each time step S108 is executed.

[0059] In step S109, the control unit 26 controls the process to continue the printing operation of the stacked body A by the stacking head 18 if the period during which it is determined that a printing abnormality has occurred (second period) is less than a predetermined period, based on the period since the start of the printing operation of the stacked body A by the stacking head 18 in step S101 (first period). If the count value of the abnormality determination counter is less than a predetermined abnormality count value, the control unit 26 determines that the period during which it is determined that a printing abnormality has occurred is less than a predetermined period, and repeats the process from step S104 onwards to continue the printing operation of the stacked body A by the stacking head 18.

[0060] Furthermore, the control unit 26 controls the process to stop the printing operation of the stacked body A by the stacking head 18 if the period during which it is determined that a printing abnormality has occurred (second period) is longer than a predetermined period, during the period from when the printing operation of the stacked body A by the stacking head 18 started in step S101 (first period). The control unit 26 determines that the period during which it is determined that a printing abnormality has occurred is longer than a predetermined period if the count value of the abnormality determination counter is greater than a predetermined abnormality count value, and stops the printing operation of the stacked body A by the stacking head 18 in step S110.

[0061] In step S111, the notification unit 24 notifies the operator via the display unit (not shown) of the three-dimensional additive manufacturing apparatus 1 of information identifying the injection nozzle corresponding to the molding anomaly among the multiple injection nozzles 18A, 18B, and 18C, and information indicating that a molding anomaly has occurred. In the example shown in Figure 8, in the determination area JA, injection area IAc is included in the low-luminance area LA, and injection areas IAa and IAb are included in the molten pool M.

[0062] The reason why the injection region IAc is included in the low-brightness region LA is that clogging has occurred in at least one of the injection nozzles 18A and 18B corresponding to injection regions IAa and IAb, respectively, and the amount of powder injected from injection nozzle 18C has increased. As a result of the increased amount of powder injected from injection nozzle 18C, the powder in injection region IAc does not melt sufficiently, and the amount of unmelted powder increases. Therefore, the notification unit 24 notifies the operator that clogging has occurred in at least one of the injection nozzles 18A and 18B, and that a molding abnormality has occurred.

[0063] Furthermore, if clogging occurs in any of the multiple injection nozzles 18A, 18B, or 18C, and the amount of powder injected from the other injection nozzles increases, printing abnormalities are likely to occur in the injection region located furthest downstream in the printing direction MD (either injection region IAa, IAb, or IAc). On the other hand, in injection regions other than the injection region located furthest downstream in the printing direction MD, printing abnormalities are less likely to occur even if the amount of powder injected increases.

[0064] This is because the injection region located furthest downstream in the fabrication direction MD is positioned downstream of the point through which the light beam L passes, which is the irradiation position. In the fabrication direction MD, the injection region (any of injection regions IAa, IAb, or IAc) located upstream of the point through which the light beam L passes, which is the irradiation position, receives sufficient energy from the light beam L, so even if the amount of powder injected increases, the powder is easily melted by the energy of the light beam L.

[0065] On the other hand, in the fabrication direction MD, the injection region (either injection region IAa, IAb, or IAc) located downstream of the point where the light beam L is irradiated along axis Z cannot receive sufficient energy from the light beam L, and when the amount of powder injected increases, the powder is less likely to melt due to the energy of the light beam L.

[0066] In the flowchart described above, in step S105, the low-luminance region LA and the molten pool M are extracted from the build area FA, and it is determined that a build defect has occurred if the proportion of the low-luminance region LA in the judgment area JA is equal to or greater than a predetermined proportion. However, other embodiments are also possible.

[0067] Figure 9 shows a first modified example of the analysis results of the judgment image shown in Figure 7. In the first modified example, the judgment unit 22 identifies the position Pmin where the distance from the boundary line BL to the center C1 of the circular region is minimized. The judgment unit 22 then determines that a manufacturing abnormality has occurred if the minimum value Dmin of the distance from the boundary line BL to the center C1 of the circular region is less than or equal to a predetermined distance (for example, 70% of the radius R1 of the circular region approximating the boundary line BL) in the approximately semicircular judgment region JA on the downstream side of the manufacturing direction MD within the circular region approximating the boundary line BL.

[0068] Figure 10 shows a second modified example of the analysis results of the judgment image shown in Figure 7. In the second modified example, the judgment unit 22 identifies the position Pmin where the distance from the boundary line BL to the center C1 of the circular region is minimum, and the position Pmax where the distance from the boundary line BL to the center C1 of the circular region is maximum.

[0069] The determination unit 22 then determines that a molding anomaly has occurred if, in the approximately semicircular determination region JA on the downstream side of the molding direction MD within the circular region approximating the boundary line BL, the roundness Rd of the boundary line BL with respect to the center C1 of the circular region is greater than or equal to a predetermined value (for example, 30% of the radius R1 of the circular region approximating the boundary line BL). Here, the roundness is the value obtained by subtracting the minimum value Dmin of the distance from the boundary line BL to the center C1 of the circular region from the maximum value Dmax of the distance from the boundary line BL to the center C1 of the circular region.

[0070] The functions and effects of the three-dimensional stacking apparatus 1 of this embodiment, as described above, will now be explained. According to the three-dimensional additive manufacturing apparatus 1 of this embodiment, the head moving unit 20 and the base moving unit 12 move the additive manufacturing head 18 relative to the base unit 14 in the manufacturing direction MD, thereby manufacturing a laminated body A in the manufacturing direction MD by the additive manufacturing head 18. The additive manufacturing head 18 sprays powder from a plurality of spray nozzles 18A, 18B, and 18C toward the manufacturing area of ​​the base unit 14, and irradiates the manufacturing area with a light beam L to melt the powder, thereby manufacturing a laminated body A on the base unit 14.

[0071] The determination unit 22 determines whether a manufacturing abnormality has occurred based on the shape of the molten pool M in the determination region JA downstream of the manufacturing direction MD in the image of the fabricated area including the molten pool M captured by the imaging unit 18F. If a blockage occurs in any of the multiple injection nozzles 18A, 18B, or 18C and the amount of powder injected increases in the determination region JA downstream of the manufacturing direction MD, the energy from the irradiation of the light beam L becomes insufficient, making it easy for manufacturing abnormalities to occur. Therefore, it is possible to appropriately determine whether a manufacturing abnormality has occurred based on the shape of the molten pool M in the determination region JA downstream of the manufacturing direction MD.

[0072] When the amount of powder ejected from the injection nozzle 18C corresponding to the injection region IAc furthest downstream in the molding direction MD increases, the proportion of the low-luminance region LA increases in the approximately semicircular determination region JA downstream in the molding direction MD, which is part of the circular region approximating the boundary line BL between the molten pool M and the low-luminance region LA. According to the three-dimensional additive manufacturing apparatus 1 of this embodiment, it is possible to appropriately determine that a molding abnormality has occurred when the proportion of the low-luminance region LA in the determination region JA is equal to or greater than a predetermined proportion.

[0073] When the amount of powder ejected from the injection nozzle 18C corresponding to the injection area IAc furthest downstream in the molding direction MD increases, the minimum value Dmin of the distance from the boundary line BL to the center C1 of the circular region decreases in the approximately semicircular determination region JA downstream in the molding direction MD, which is a circular region approximating the boundary line BL between the molten pool M and the low-luminance region LA. According to the three-dimensional additive manufacturing apparatus 1 of this embodiment, it is possible to appropriately determine that a molding abnormality has occurred when the minimum value Dmin of the distance from the boundary line BL to the center C1 of the circular region is less than or equal to a predetermined distance.

[0074] When the amount of powder ejected from the injection nozzle 18C corresponding to the injection region IAc furthest downstream in the molding direction MD increases, the roundness Rd of the boundary line BL with respect to the center C1 of the circular region increases in the approximately semicircular determination region JA downstream in the molding direction MD, which is a circular region approximating the boundary line BL between the molten pool M and the low-brightness region LA. According to the three-dimensional additive manufacturing apparatus 1 of this embodiment, it is possible to appropriately determine that a molding abnormality has occurred when the roundness Rd of the boundary line BL with respect to the center C1 of the circular region is greater than or equal to a predetermined value.

[0075] According to the three-dimensional stacking apparatus 1 of this embodiment, the stacking head 18 can identify the printing direction MD in which the stacked body A is fabricated based on the image captured by the imaging unit 18F, and can appropriately set the determination area JA for determining printing abnormalities.

[0076] According to the three-dimensional additive manufacturing apparatus 1 of this embodiment, the notification unit 24 can appropriately notify the operator of information that identifies the injection nozzles 18A, 18C, and 18C corresponding to the molding abnormality among the multiple injection nozzles 18A, 18B, and 18C.

[0077] According to the three-dimensional additive manufacturing apparatus 1 of this embodiment, if the second period in which the determination unit 22 determines that a manufacturing abnormality has occurred during the first period in which the additive manufacturing head 18 manufactures the additive body A is longer than a predetermined period, the operation of the additive manufacturing head 18 can be stopped, thereby preventing the occurrence of further manufacturing abnormalities.

[0078] The three-dimensional additive manufacturing apparatus and the method for determining manufacturing defects described in each embodiment above can be understood, for example, as follows.

[0079] A three-dimensional additive manufacturing apparatus (1) according to a first aspect of the present disclosure comprises a molding unit (18) that melts powder onto an object to be laminated (14) to form a laminate, a moving unit (12, 20) that moves the molding unit in the molding direction (MD) relative to the object to be laminated, and a determination unit (22) that determines whether or not a molding abnormality has occurred in the laminate, wherein the molding unit comprises a plurality of injection nozzles (18A, 18B, 18C) that spray the powder toward the molding area of ​​the object to be laminated, and a bias of a predetermined percentage or more in the amount of powder sprayed from the plurality of injection nozzles The determination unit includes a powder supply unit (18D) that supplies the powder to a plurality of injection nozzles to prevent the occurrence of defects, a light irradiation unit (18E) that irradiates the molding area with a light beam to melt the powder and form a laminate on the object to be laminated, and an imaging unit (18F) that captures an image of the molding area including a molten region (M) formed by the molten powder, and the determination unit determines whether the molding defect has occurred based on the shape of the molten region in the determination region (JA) on the downstream side of the molding direction of the image captured by the imaging unit.

[0080] According to the three-dimensional additive manufacturing apparatus of the first aspect of this disclosure, the moving unit moves the manufacturing unit in the manufacturing direction relative to the object to be laminated, thereby creating a laminate by the manufacturing unit in the manufacturing direction. The manufacturing unit sprays powder from multiple spray nozzles toward the manufacturing area of ​​the object to be laminated, and irradiates the manufacturing area with a light beam to melt the powder, thereby creating a laminate on the object to be laminated.

[0081] The determination unit determines whether a manufacturing abnormality has occurred based on the shape of the molten region in the determination region downstream in the manufacturing direction of the image of the fabricated area, including the molten region, captured by the imaging unit. If a blockage occurs in any of the multiple injection nozzles and the amount of powder injected increases in the determination region downstream in the manufacturing direction, the energy from the light beam irradiation becomes insufficient, making it easy for manufacturing abnormalities to occur. Therefore, it is possible to appropriately determine whether a manufacturing abnormality has occurred based on the shape of the molten region in the determination region downstream in the manufacturing direction.

[0082] A three-dimensional additive manufacturing apparatus according to a second aspect of the present disclosure further comprises the following configuration in the first aspect: The determination unit determines that a manufacturing abnormality has occurred if the proportion of the low-luminance region is greater than or equal to a predetermined proportion in the substantially semicircular determination region downstream in the manufacturing direction, which is a circular region approximating the boundary line between the molten region having a luminance value higher than the determination luminance value and the low-luminance region having a luminance value lower than the determination luminance value.

[0083] When the amount of powder ejected from the ejection nozzle corresponding to the ejection region furthest downstream in the molding direction increases, the proportion of the low-luminance region increases in the approximately semicircular determination region downstream in the molding direction, which is a circular region approximating the boundary line between the molten region and the low-luminance region. According to the three-dimensional additive manufacturing apparatus of the second aspect of this disclosure, it is possible to appropriately determine that a molding abnormality has occurred when the proportion of the low-luminance region in the determination region is equal to or greater than a predetermined proportion.

[0084] A three-dimensional additive manufacturing apparatus according to a third aspect of the present disclosure further comprises the following configuration in the first aspect: The determination unit determines that a manufacturing abnormality has occurred in a substantially semicircular determination region downstream in the manufacturing direction, which is a circular region approximating the boundary line between the molten region having a brightness value higher than the determination brightness value and the low brightness region having a brightness value lower than the determination brightness value, if the minimum distance from the boundary line to the center of the circular region is less than or equal to a predetermined distance.

[0085] When the amount of powder ejected from the ejection nozzle corresponding to the ejection region furthest downstream in the molding direction increases, the minimum distance from the boundary line to the center of the circular region decreases in the approximately semicircular determination region downstream in the molding direction, which approximates the boundary line between the molten region and the low-brightness region. According to the three-dimensional additive manufacturing apparatus of the third aspect of this disclosure, it is possible to appropriately determine that a molding abnormality has occurred when the minimum distance from the boundary line to the center of the circular region is less than or equal to a predetermined distance.

[0086] A three-dimensional additive manufacturing apparatus according to a fourth aspect of the present disclosure further comprises the following configuration in the first aspect: The determination unit determines that a manufacturing abnormality has occurred in a substantially semicircular determination region downstream in the manufacturing direction, which is a circular region approximating the boundary line between the molten region having a brightness value higher than the determination brightness value and the low-brightness region having a brightness value lower than the determination brightness value, if the roundness of the boundary line with respect to the center of the circular region is greater than or equal to a predetermined value.

[0087] When the amount of powder ejected from the ejection nozzle corresponding to the ejection region furthest downstream in the molding direction increases, the roundness of the boundary line with respect to the center of the circular region increases in the approximately semicircular determination region downstream in the molding direction of the circular region that approximates the boundary line between the molten region and the low-brightness region. According to the three-dimensional additive manufacturing apparatus of the fourth aspect of this disclosure, it is possible to appropriately determine that a molding abnormality has occurred when the roundness of the boundary line with respect to the center of the circular region is greater than or equal to a predetermined value.

[0088] A three-dimensional additive manufacturing apparatus according to a fifth aspect of this disclosure further comprises the following configuration in any of the second to fourth aspects: The determination unit identifies the direction toward the center of the low-luminance region from the irradiation position where the light irradiation unit irradiates the light beam as the manufacturing direction. According to the three-dimensional stacking apparatus of the fifth aspect of this disclosure, the printing unit can identify the printing direction in which it prints the stacked material based on the image captured by the imaging unit, and can appropriately set a determination area for determining printing abnormalities.

[0089] A three-dimensional additive manufacturing apparatus according to the sixth aspect of this disclosure further comprises the following configuration in any of the first to fourth aspects: namely, a notification unit (24) that notifies information identifying the injection nozzle corresponding to the molding abnormality among a plurality of injection nozzles. According to the three-dimensional additive manufacturing apparatus of the sixth aspect of this disclosure, the notification unit can appropriately notify the operator of information that identifies the injection nozzle corresponding to the molding abnormality among a plurality of injection nozzles.

[0090] A three-dimensional additive manufacturing apparatus according to the seventh aspect of this disclosure further comprises the following configuration in any of the first to fourth aspects: that is, a control unit (26) that controls the operation of the manufacturing unit to continue if the second period during which the determination unit determines that a manufacturing abnormality has occurred is less than a predetermined period, and to stop the operation of the manufacturing unit if the second period is equal to or greater than the predetermined period, during a first period in which the manufacturing unit performs a manufacturing operation to manufacture the additive manufacturing body.

[0091] According to the three-dimensional additive manufacturing apparatus of the seventh aspect of this disclosure, if the second period in which the determination unit determines that a manufacturing abnormality has occurred during the first period in which the manufacturing unit performs a manufacturing operation to create a laminate is longer than a predetermined period, the operation of the manufacturing unit can be stopped to prevent further manufacturing abnormalities from occurring.

[0092] A method for determining a manufacturing anomaly in a three-dimensional additive manufacturing apparatus according to an eighth aspect of the present disclosure, wherein the three-dimensional additive manufacturing apparatus comprises a manufacturing unit that melts the powder onto the object to be laminated to form the laminate, and a moving unit that moves the manufacturing unit in the manufacturing direction relative to the object to be laminated, wherein the manufacturing unit comprises a plurality of spray nozzles that spray the powder toward the manufacturing location of the object to be laminated, a powder supply unit that supplies the powder to the plurality of spray nozzles so that the amount of powder sprayed from the plurality of spray nozzles does not become biased by more than a predetermined proportion, and a light irradiation unit that irradiates the manufacturing location with a light beam to melt the powder and form a laminate on the object to be laminated, and comprises an imaging step (S104) for capturing an image of the manufacturing location including a molten region formed by the molten powder, and a determination step (S106) for determining whether a manufacturing anomaly has occurred in the laminate based on the shape of the molten region in the determination region downstream of the manufacturing direction of the image captured by the imaging step.

[0093] According to the molding anomaly determination method of the eighth aspect of this disclosure, the moving part moves the molding part in the molding direction relative to the object to be laminated, thereby forming a laminate by the molding part in the molding direction. The molding part forms a laminate on the object to be laminated by spraying powder from multiple spray nozzles toward the molding area of ​​the object to be laminated and irradiating the molding area with a light beam to melt the powder.

[0094] The determination step determines whether a manufacturing anomaly has occurred based on the shape of the molten region in the determination area downstream in the manufacturing direction of the image of the fabricated area, including the molten region, captured by the imaging step. If a blockage occurs in any of the multiple injection nozzles and the amount of powder injected increases in the determination area downstream in the manufacturing direction, the energy from the light beam irradiation becomes insufficient, making manufacturing anomalies more likely to occur. Therefore, it is possible to appropriately determine whether a manufacturing anomaly has occurred based on the shape of the molten region in the determination area downstream in the manufacturing direction. [Explanation of Symbols]

[0095] 1. Three-dimensional stacking apparatus 2 Powder source 3. Supply Line 10 units 12 Base movement section 12A 1st moving part 12B 2nd moving part 12C Rotating part 14. Base (object to be stacked) 16 base 18. Layer head (printing unit) 18A, 18B, 18C spray nozzles 18Aa,18Ba injection port 18D Powder supply section 18Da, 18Db, 18Dc supply line 18E Light irradiation section 18Ea, 18Eb Mirror 18F Imaging Unit 18G beam path 18Ga light beam emitter 18Gb optical element 18Gc protective glass 18Gd inner surface 18a Main body 18b End 20 Head movement section 22 Judgment section 24 Hochi Department 26 Control Unit A laminate B Bead BL boundary line C1 center CG center of gravity position CP Intersection FA printing area I Infrared light IAa,IAb,IAc injection area JA judgment area L Light Beam L1 straight line LA Low-luminance area M molten pool (molten area) MD printing direction P powder Pmax position Pmin position R1 radius Rd (Roundness)

Claims

1. A molding unit that melts powder onto the object to be layered to create a layered structure, A moving unit that moves the molding unit in the molding direction relative to the object to be laminated, The system includes a determination unit that determines whether or not a molding abnormality has occurred in the laminate, The aforementioned molding section is Multiple spray nozzles for spraying the powder toward the molding area of ​​the object to be layered, A powder supply unit that supplies the powder to multiple injection nozzles so as not to cause a bias in the amount of powder sprayed from multiple injection nozzles exceeding a predetermined percentage, A light irradiation unit that irradiates the molding area with a light beam to melt the powder and form the laminate on the object to be laminated, It includes an imaging unit that captures an image of the molded area including the molten region formed by the molten powder, The determination unit determines whether a manufacturing abnormality has occurred based on the shape of the molten region in the determination region downstream of the manufacturing direction of the image captured by the imaging unit.

2. The three-dimensional additive manufacturing apparatus according to claim 1, wherein the determination unit determines that a manufacturing abnormality has occurred in the substantially semicircular determination region downstream of the manufacturing direction, which is a circular region approximating the boundary line between the molten region having a brightness value higher than the determination brightness value and the low-brightness region having a brightness value lower than the determination brightness value, if the proportion of the low-brightness region is greater than or equal to a predetermined proportion.

3. The three-dimensional additive manufacturing apparatus according to claim 1, wherein the determination unit determines that a manufacturing abnormality has occurred in the substantially semicircular determination region downstream in the manufacturing direction of a circular region that approximates the boundary line between the molten region having a brightness value higher than the determination brightness value and the low brightness region having a brightness value lower than the determination brightness value, if the minimum distance from the boundary line to the center of the circular region is less than or equal to a predetermined distance.

4. The three-dimensional additive manufacturing apparatus according to claim 1, wherein the determination unit determines that a manufacturing abnormality has occurred in the substantially semicircular determination region downstream in the manufacturing direction of a circular region that approximates the boundary line between the molten region having a brightness value higher than the determination brightness value and the low brightness region having a brightness value lower than the determination brightness value, if the roundness of the boundary line with respect to the center of the circular region is greater than or equal to a predetermined value.

5. The three-dimensional additive manufacturing apparatus according to any one of claims 2 to 4, wherein the determination unit identifies the direction toward the center of the low-luminance region from the irradiation position where the light irradiation unit irradiates the light beam as the manufacturing direction.

6. A three-dimensional additive manufacturing apparatus according to any one of claims 1 to 4, further comprising a notification unit that notifies information identifying the injection nozzle corresponding to the molding abnormality among a plurality of injection nozzles.

7. A three-dimensional additive manufacturing apparatus according to any one of claims 1 to 4, comprising a control unit that controls the operation of the manufacturing unit to continue if the second period during which the determination unit determines that a manufacturing abnormality has occurred is less than a predetermined period, and to stop the operation of the manufacturing unit if the second period is equal to or greater than the predetermined period.

8. A method for determining abnormalities in the manufacturing process of a three-dimensional additive manufacturing apparatus that melts powder onto an object to be layered to create a laminate, The three-dimensional stacking apparatus is A molding unit that melts the powder onto the object to be laminated to form the laminate, The system includes a moving part that moves the molding part in the molding direction relative to the object to be laminated, The aforementioned molding section is Multiple spray nozzles for spraying the powder toward the molding area of ​​the object to be layered, A powder supply unit that supplies the powder to multiple injection nozzles so as not to cause a bias in the amount of powder sprayed from multiple injection nozzles exceeding a predetermined percentage, It has a light irradiation unit that irradiates the molding area with a light beam to melt the powder and form the laminate on the object to be laminated, An imaging step of capturing an image of the molded area including the molten region formed by the molten powder, A method for determining a manufacturing abnormality, comprising: a determination step of determining whether a manufacturing abnormality has occurred in the laminate based on the shape of the molten region in the determination region downstream of the manufacturing direction of the image captured by the imaging step.

Images