Defect detection device and defect detection method

Abstract

To provide a defect detection device and a defect detection method suitable for detecting an internal defect of an object to be 3D molded.SOLUTION: A defect detection device according to at least one embodiment of the present disclosure comprises: a laser irradiation device that can radiate a laser beam for 3D molding of an object and can radiate a pulse laser beam to the object for generating ultrasonic waves in the object; an irradiation control device that controls irradiation of the laser beam; a vibration measurement device that is configured to measure vibration of the object based on the ultrasonic waves; and a detector that is configured to detect the presence of an internal defect of the object based on the vibration detected by the vibration measurement device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a defect detection apparatus and a defect detection method. [Background technology]

[0002] In recent years, additive manufacturing (AM) technology has been attracting attention with the aim of improving performance through complex structures, and devices that manufacture three-dimensional objects (3D models) through additive manufacturing using electron beams or laser beams have become widespread. For example, Patent Document 1 discloses a device that monitors the temperature of the growing part in additive manufacturing and adjusts the output of the irradiated beam based on the temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-73796 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, when constructing a complex structure, it is common to assemble multiple castings (casting and forging parts). In this case, inspections of defects (cracks, shrinkage cavities, etc.) in castings and forgings can be performed by applying relatively simple methods such as ultrasonic testing, eddy current testing, and radiography to each casting and forging part.

[0005] However, 3D modeling using AM technology is a one-piece simultaneous molding using metal powder as the material, so there are no intermediate products, and defect inspection must be performed on the final shape. In this case, it is difficult to evaluate defects at a position away from the outer surface of the final shape using the simple inspection method described above. Evaluation using X-ray CT is also possible, but there is a problem that it cannot be used for large 3D modeling products. In addition, because defect inspection is performed on the final shape, if an internal defect is found, the modeling must be started again from the beginning, creating a risk of rework. To solve these problems, it is important to be able to detect internal defects during modeling. Patent Document 1 does not disclose a method for solving such problems of internal defects.

[0006] The laser ultrasonic method is known as a method for detecting internal defects without contacting the surface. The laser ultrasonic method is a technology in which the surface of an object to be inspected is locally heated by irradiating the surface with a pulsed laser beam, generating ultrasonic waves by thermal expansion or ablation, and the ultrasonic waves propagate through the object to be inspected, are reflected or scattered by internal defects, and then propagate back to the surface and are measured by a detection device such as a laser interferometer.

[0007] In defect detection using the laser ultrasonic method, it is necessary to observe the reflected wave from the defect when irradiating it with pulsed laser light. However, when inspecting defects located at a shallow position (near the surface), the reflected wave from the defect is buried in the surface vibration displacement caused by the incident wave. Therefore, it is difficult to apply this method to detect defects located at a shallow position from the surface that occur during 3D printing.

[0008] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a defect detection device and a defect detection method suitable for detecting internal defects in an object to be 3D printed. [Means for solving the problem]

[0009] (1) A defect detection device according to at least one embodiment of the present disclosure, A laser irradiation device capable of irradiating a laser beam to an object for 3D printing and irradiating a pulsed laser beam to the object for generating ultrasonic waves in the object; an irradiation control device for controlling the irradiation of the laser light; a vibration measuring device configured to measure vibration of the object based on the ultrasonic waves; a detection device configured to detect the presence or absence of an internal defect of the object based on the vibration detected by the vibration measuring device; and Equipped with.

[0010] (2) A defect detection method according to at least one embodiment of the present disclosure, A step of irradiating a laser beam from a laser irradiation device to 3D model an object; irradiating the target with pulsed laser light from the laser irradiation device to generate ultrasonic waves in the target; measuring vibration of the object based on the ultrasonic waves; detecting the presence or absence of an internal defect of the object based on the measured vibration; Equipped with.

[0011] (3) A defect detection method according to at least one embodiment of the present disclosure, irradiating a pulsed laser beam from a laser irradiation device onto an object in order to 3D model the object and simultaneously generate ultrasonic waves in the object; measuring vibration of the object based on the ultrasonic waves; detecting the presence or absence of an internal defect of the object based on the measured vibration; Equipped with. Effect of the Invention

[0012] According to at least one embodiment of the present disclosure, it is possible to provide a defect detection device and a defect detection method suitable for detecting internal defects in an object to be 3D printed. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a molding apparatus according to an embodiment. [Diagram 2] FIG. 1 is a diagram illustrating a schematic configuration of a molding apparatus according to an embodiment. [Diagram 3] FIG. 1 is a diagram illustrating a schematic configuration of a molding apparatus according to an embodiment. [Figure 4] FIG. 1 is a diagram illustrating a schematic configuration of a molding apparatus according to an embodiment. [Diagram 5] FIG. 1 is a diagram illustrating a schematic configuration of a molding apparatus according to an embodiment. [Figure 6] 11 is a timing chart of laser light irradiation in the first method. [Figure 7] 13 is a timing chart of laser light irradiation in the second method. [Figure 8] 11 is a flowchart showing a procedure for performing a process of detecting 3D shapes and internal defects by a first method. [Figure 9] FIG. 1 is a diagram illustrating an internal defect of an object. [Figure 10] FIG. 2 is a diagram showing functional blocks of a calculation device relating to processing in a step of detecting an internal defect. [Figure 11A] 1 is an example of a graph showing the amplitude of vibration obtained from a detection device. [Figure 11B] 11 is an example of a graph showing vibrations after extracting information required for detecting the presence or absence of an internal defect. [Figure 11C] 13 is an example of a graph showing a processing result of FFT processing. [Figure 12] FIG. 4 is a diagram showing an example of a map created by a map creating unit; [Figure 13] 13 is a flowchart showing a procedure for performing a process for detecting 3D shapes and internal defects using a second method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such a configuration, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions excluding the presence of other elements.

[0015] (Overall configuration of a molding apparatus equipped with a defect detection device) Hereinafter, a modeling apparatus 300 according to several embodiments will be described. Fig. 1 to Fig. 5 are diagrams that outline the configuration of the modeling apparatus 300 according to each embodiment. Note that optical systems such as collimator lenses and condenser lenses are omitted in Fig. 1 to Fig. 5. In the following description, a modeling apparatus 300 including a defect detection device 200 will be described, but the defect detection device 200 may be an apparatus independent of the modeling apparatus 300.

[0016] 1 to 5, the modeling apparatus 300 includes a defect detection apparatus 200 for detecting internal defects. The modeling apparatus 300 is, for example, an apparatus that performs additive manufacturing (AM) using a powder bed method. Note that the modeling apparatus 300 may be an apparatus that performs modeling using an LMD (Laser Metal Deposition) method.

[0017] (Laser irradiation device 201) 1 to 5, the laser irradiation device 201 is configured to be able to irradiate raw material powder 303 (e.g., alloy powder) spread on a base plate 301 of the modeling apparatus 300 as a powder bed 302 with a continuous wave laser beam B1 for melting the raw material powder to model a 3D shape, and to irradiate a target object T with a pulsed laser beam B2 for generating ultrasonic waves in the target object T, as described later (see FIG. 5). In the following description, the continuous wave laser beam B1 will also be simply referred to as laser beam B1. 1 to 5, the laser irradiation device 201 is provided with a pulse oscillation mode, which makes it possible to melt the raw material powder to form a 3D shape and simultaneously generate ultrasonic waves in the target object T. That is, in the embodiment shown in Fig. 1 to 5, the laser irradiation device 201 may be configured to be able to melt the raw material powder to form a 3D shape and simultaneously irradiate the target object T with pulse laser light B4 to generate ultrasonic waves. 1 to 5, the laser irradiation device 201 for 3D printing in the modeling apparatus 300 is also used as an irradiation device of pulsed laser beams B2 and B4 for generating ultrasonic waves in the target object T. In the embodiment shown in Fig. 1 to 5, the laser irradiation device 201 is a component of the modeling apparatus 300 and also a component of the defect detection device 200.

[0018] (1st Galvanometer Mirror 204) 1 to 5, the modeling apparatus 300 includes a galvanometer mirror (first galvanometer mirror) 204, and can change the direction of the continuous wave laser beam B1 or the pulsed laser beam B4 to scan the powder bed 302. That is, in the embodiment shown in Fig. 1 to 5, the defect detection apparatus 200 includes the first galvanometer mirror 204 for scanning the continuous wave laser beam B1 or the pulsed laser beam B4 for 3D modeling the object T. 1 to 5, the first galvanometer mirror 204 can also scan with the pulsed laser beam B2. Therefore, in the embodiment shown in Fig. 1 to 5, the first galvanometer mirror 204 can change the position (ultrasonic excitation point) that is the origin of generation of ultrasonic waves in the target T by scanning with the pulsed laser beam B2 or the pulsed laser beam B4. According to the embodiment shown in FIGS. 1 to 5, since there is no need to move the laser irradiation device 201 itself, the mechanism for scanning with the continuous wave laser beam B1 or the pulsed laser beam B4 can be made compact.

[0019] In the modeling apparatus 300 according to some embodiments, the continuous wave laser beam B1 or the pulsed laser beam B4 can be irradiated along a shape based on any CAD by scanning the continuous wave laser beam B1 or the pulsed laser beam B4 with the first galvanometer mirror 204. In this way, the laser irradiation device 201 melts and solidifies the raw material powder 303 to 3D model the target T.

[0020] In the embodiment shown in Figures 1 to 5, the defect detection device 200 is equipped with a laser irradiation device 201 that is capable of irradiating a continuous wave laser beam B1 or a pulsed laser beam B4 to 3D model an object, as described above, and is also capable of irradiating a pulsed laser beam B2 onto the object T to generate ultrasonic waves in the object T.

[0021] (Defect detection device 200) In the embodiment shown in Figures 1 to 5, the defect detection apparatus 200 comprises a detection apparatus 220 configured to detect the presence or absence of an internal defect in the object T, and a control apparatus 230 configured to control the same. In the embodiment shown in Figures 1 to 5, the detection device 220 includes a vibration measuring device 221 configured to measure vibrations of the object T based on ultrasonic waves, and a calculation device 222 configured to detect the presence or absence of an internal defect in the object T based on the vibrations detected by the vibration measuring device 221.

[0022] (Vibration Measuring Device 221) 1 to 3, the vibration measuring device 221 may be, for example, a laser interferometer 221A. In this case, the vibration measuring device 221 is configured to irradiate the object T with laser light B3 and receive the reflected light to measure the vibration, i.e., the displacement, of the surface of the object T.

[0023] 1 to 3, a Doppler vibrometer 221B may be provided instead of the laser interferometer. That is, the vibration measuring device 221 may include either the laser interferometer 221A or the Doppler vibrometer 221B.

[0024] 4 and 5, the vibration measuring device 221 may be configured with a contact transducer 221t, which is a probe that detects vibrations by being used in direct contact with the object T, instead of a non-contact detection device such as a laser interferometer 221A, and a data logger 221D. That is, the vibration measuring device 221 may include the contact transducer 221t for measuring the vibrations of the object T based on ultrasonic waves. As shown in FIG. 4, the contact transducer 221t may be disposed on the upper surface of the target object T. As shown in FIG. 5, the contact transducer 221t may be installed on a base plate 301 of the modeling apparatus 300.

[0025] (Arithmetic unit 222) 1 to 5, the arithmetic device 222 is configured to include a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), etc. In the embodiment shown in Fig. 1 to 5, the arithmetic device 222 is configured to detect the presence or absence of an internal defect in the object T based on a specific frequency component in the vibration of the object T, for example, by executing a program stored in the ROM or RAM. An internal defect is an internal molding defect such as a void that is not visible from the surface. 1 to 5, the arithmetic device 222 includes the following functional blocks: a "time waveform storage memory" that stores the received ultrasonic waveform, a "window function extraction unit" that applies a window function to the ultrasonic waveform to extract an arbitrary waveform, an "FFT processing unit" that performs FFT processing on the extracted waveform, an "FFT result analysis unit" that analyzes the FFT processing results, and a "measurement result map creation unit" that plots the FFT processing results in a map. The FFT result analysis unit extracts the sum of frequency components, the maximum amplitude value in a certain frequency range, the FFT amplitude value of a certain frequency, etc.

[0026] 1 to 5, the defect detection device 200 may include, for example, a photodetector 206. The photodetector 206 is for detecting the timing at which the pulsed laser beam B2 or the pulsed laser beam B4 is irradiated onto the object T, and is configured to input a detection signal to the calculation device 222.

[0027] In the embodiment shown in FIG. 1, the first galvanometer mirror 204 can change the direction of the laser light B3 from the laser interferometer 221A or the Doppler vibrometer 221B to scan the powder bed, and can guide the laser light B3 reflected from the surface of the target object T to the half mirror 205 described next.

[0028] In the embodiment shown in Fig. 1, the defect detection device 200 includes a half mirror 205. In this case, as shown in Fig. 1, the continuous wave laser beam B1 and the pulsed laser beam B2 or the pulsed laser beam B4, and the laser beam B3 can be made incident on the first galvanometer mirror 204 via the half mirror 205, and the directions of the continuous wave laser beam B1 and the pulsed laser beam B2 or the pulsed laser beam B4, and the laser beam B3 can be changed. This configuration is suitable for the case where the laser beam B3 is irradiated at the same position as the irradiation position of the pulsed laser beam B2 or the pulsed laser beam B4.

[0029] The defect detection device 200 may not include the half mirror 205. For example, the defect detection device 200 may include a beam splitter instead of the half mirror 205. The defect detection device 200 may not include the half mirror 205 and the beam splitter, and may be configured to be capable of independently scanning the continuous wave laser beam B1 and the pulsed laser beam B2, or the pulsed laser beam B4 and the laser beam B3, as shown in FIG. 2, for example.

[0030] (2nd Galvanometer Mirror 207) 2, the defect detection device 200 includes a galvanometer mirror (second galvanometer mirror) 207 different from the first galvanometer mirror 204. The second galvanometer mirror 207 is a galvanometer mirror for scanning a measurement laser beam from the laser interferometer 221A or the Doppler vibrometer 221B. In the embodiment shown in FIG. 2, the first galvanometer mirror 204 can change the direction of the continuous wave laser light B1 and the pulsed laser light B2, or the pulsed laser light B4 to scan the powder bed, and the second galvanometer mirror 207 can change the direction of the laser light B3 to scan the powder bed. According to the embodiment shown in FIG. 2, since the measurement laser beam B3 can be scanned, the laser beam B3 can be irradiated to the same position as the irradiation position of the pulsed laser beam B2 or the pulsed laser beam B4.

[0031] 3, the defect detection device 200 includes a mirror 208 for reflecting the laser light B3. In the embodiment shown in Fig. 3, the irradiation position of the laser light B3 from the laser interferometer 221A or the Doppler vibrometer 221B on the target T is a fixed position that is set in advance by adjusting the attitude of the mirror 208.

[0032] (Control device 230) 1 to 5, the control device 230 is composed of a CPU, a RAM, a ROM, etc. The control device 230 controls the operation of the entire device, for example, by executing a program stored in the ROM or RAM. The control device 230 also stores various data (for example, design information of the target object T, etc.) in the ROM or RAM. In the embodiment shown in Figures 1 to 5, the control device 230 includes an irradiation control device 231 that controls the irradiation of the continuous wave laser beam B1 and the pulsed laser beam B2, or the pulsed laser beam B4, and a galvanometer mirror control device 232 that controls the first galvanometer mirror 204 and the second galvanometer mirror 207 described above. The irradiation controller 231 may be configured with a CPU, RAM, ROM, etc. different from the above-mentioned CPU, RAM, ROM, etc. in the controller 230, or may be configured as a part of the functional blocks in the controller 230. Similarly, the galvano mirror control device 232 may be composed of a CPU, RAM, ROM, etc. different from the above-mentioned CPU, RAM, ROM, etc. in the control device 230, or may be configured as part of the functional block in the control device 230.

[0033] As described above, the defect detection device 200 according to some embodiments includes the laser irradiation device 201, the irradiation control device 231, the vibration measurement device 221, and the detection device 220 (the calculation device 222). This allows the same laser irradiation device 201 to irradiate the object T with laser light (continuous wave laser light B1 or pulsed laser light B4) for 3D printing and the object T with pulsed laser light (pulsed laser light B2 or pulsed laser light B4) for generating ultrasonic waves in the object T, thereby simplifying the device configurations of the defect detection device 200 and the 3D printing device 300. This makes it possible to provide the defect detection device 200 suitable for detecting internal defects in the object T to be 3D printed.

[0034] As described above, in the defect detection device 200 according to some embodiments, the irradiation control device 231 may control the laser irradiation device 201 to irradiate pulsed laser light (pulsed laser light B4) to 3D print the object T. As described above, if ultrasonic waves are generated in the object T by irradiating the object T with a pulsed laser beam (pulsed laser beam B4) in order to 3D print the object T, it is possible to simultaneously perform 3D printing of the object T and detect the presence or absence of internal defects in the object T. This makes it possible to shorten the time required for 3D printing of the object T and for detecting the presence or absence of internal defects in the object T.

[0035] As described above, in the defect detection device 200 according to some embodiments, the irradiation control device 231 may control the laser irradiation device 201 to irradiate the object T with a continuous wave laser light (continuous wave laser light B1) in order to 3D model the object T. By using a continuous wave laser light (continuous wave laser light B1) for 3D printing of the object T and a pulsed laser light (pulsed laser light B2) for generating ultrasonic waves in the object T, the laser light can be irradiated under more suitable conditions for each of the cases of 3D printing of the object T and generating ultrasonic waves in the object T.

[0036] As shown in FIG. 1, in a defect detection device 200 according to one embodiment, the vibration measuring device 221 may include either a laser interferometer 221A or a Doppler vibrometer 221B, and the irradiation control device 231 may have a laser light (continuous wave laser light B1 or pulsed laser light B4) for 3D printing of the object T, and a galvanometer mirror (first galvanometer mirror 204) for scanning the measurement laser light (laser light B3) from the laser interferometer 221A or the Doppler vibrometer 221B. 1, according to the defect detection device 200 according to an embodiment, scanning of the laser light (continuous wave laser light B1 or pulsed laser light B4) for 3D printing of the object T and scanning of the measurement laser light (laser light B3) from the laser interferometer 221A or the Doppler vibrometer 221B can be performed by controlling the same galvanometer mirror (first galvanometer mirror 204). This makes it possible to simplify the defect detection device 200 compared to a case in which scanning of the laser light (continuous wave laser light B1 or pulsed laser light B4) for 3D printing of the object T and scanning of the measurement laser light (laser light B3) from the laser interferometer 221A or the Doppler vibrometer 221B are performed by separate galvanometer mirrors.

[0037] (Defect detection method) A defect detection method according to some embodiments will be described below. The defect detection method described below may be automatically executed by the control process of the control device 230, or some procedures may be executed by manual operation of the user instead of the control device 230. The defect detection method according to one embodiment is applied to, for example, powder bed additive manufacturing (AM). Note that the defect detection method can also be applied to an object when modeling by other methods such as the LMD method.

[0038] For example, as a method for detecting the presence or absence of internal defects in a region of the object T that is relatively close to the surface, pulsed laser light B2 or pulsed laser light B4 can be irradiated to generate ultrasonic waves in the object T, and the presence or absence of internal defects in the object T can be detected based on specific frequency components in the vibration of the object T based on this ultrasonic wave.

[0039] In addition, by irradiating the object T with the pulsed laser light B2 or the pulsed laser light B4, longitudinal vibrations can be generated in the object T, and the presence or absence of an internal defect in the object T can be detected based on the presence or absence of resonance of the longitudinal vibrations occurring between the surface of the object T and the internal defect. That is, when an internal defect exists in a region relatively close to the surface of the object T, the resonance frequency of the longitudinal vibration changes depending on the depth from the surface of the object T to the internal defect to be detected. By repeatedly irradiating the pulsed laser with a pulsed laser having a repetition frequency set to correspond to this resonance frequency, resonance of the longitudinal vibration occurs, and if it is possible to detect an increase in the vibration of the surface of the object T, it can be inferred that an internal defect exists.

[0040] In addition, such resonance of longitudinal vibration has a smaller amplitude and a higher frequency than the flexural vibration generated in the object T when an internal defect exists in a region relatively close to the surface of the object T. Therefore, the resonance of longitudinal vibration as described above tends to be buried in noise and difficult to detect. Therefore, by utilizing the following flexural vibration in the object T, it becomes easier to detect internal defects in the object T.

[0041] For example, if an internal defect exists in a region of the object T that is relatively close to the surface, a flexural vibration occurs having a natural frequency according to the location of the internal defect, i.e., the distance from the surface of the object T, and the size of the internal defect. The amplitude at this natural frequency is extracted, and the presence or absence of an internal defect in the object T can be detected based on the magnitude of the amplitude. Therefore, in the defect detection method according to some embodiments, an internal defect in the object T is detected as follows.

[0042] The process of detecting internal defects, which will be described later, can be carried out, for example, in the following two ways. In the first method, the process of detecting internal defects is performed for each layer when 3D modeling is performed by additive modeling. However, it is not necessarily performed for each layer, and it may be performed for each stack of multiple layers. The thickness of one layer differs depending on the material, but is generally 50 μm to 100 μm. The "multiple layers" is set to an arbitrary number, such as five layers. 6 is a timing chart of laser light irradiation in the first method. In this method, 3D printing of one or more layers is performed by irradiating the object T with a continuously oscillated continuous wave laser light B1, and then ultrasonic waves are generated in the object T by irradiating the object T with a pulsed laser light B2. The vibration of the object T based on the ultrasonic waves is measured to detect the presence or absence of internal defects in the object T.

[0043] In the second method, the object T is irradiated with a pulsed laser beam B4 in order to 3D print the object T and simultaneously generate ultrasonic waves in the object T. 7 is a timing chart of the laser beam irradiation in the second method. That is, in the second method, while 3D printing the object T every time the pulsed laser beam B4 is irradiated, ultrasonic waves are generated in the object T, and the vibration of the object T based on the ultrasonic waves is measured to detect the presence or absence of an internal defect in the object T.

[0044] In this way, in the defect detection methods according to some embodiments, it is preferable to detect the presence or absence of internal defects in the object T in the middle of being 3D printed by additive printing. Since internal defects are detected in the middle of 3D printing, the risk of major rework can be reduced.

[0045] It should be noted that the defect detection method implemented by the defect detection apparatus 200 according to some embodiments is not limited to the above-mentioned two methods. Other laser ultrasonic measurement methods are also applicable. For example, methods that can be similarly applied include a method of directly observing reflected waves from internal defects when irradiating laser light (reflection method), a method of observing the presence or absence of transmitted waves depending on the presence or absence of internal defects (transmission method), and a method of detecting differences in sound speed and gain when there is an internal defect on the path of ultrasonic waves propagating along the surface near the surface, etc. (guide wave method).

[0046] (To detect internal defects after 3D printing of one or more layers) FIG. 8 is a flowchart showing a procedure for carrying out a process for detecting 3D modeling and internal defects by the first method described above. The defect detection method shown in FIG. 8 includes step S1 of irradiating laser light, step S3 of irradiating pulsed laser light, step S5 of measuring vibrations, step S7 of detecting internal defects, and step S9 of repairing the internal defects. Fig. 9 is a schematic diagram showing an internal defect of the object T. In this figure, the defect is shown as a void. However, the defects also include cracks, incomplete fusion, and other internal molding defects that are not visible from the surface.

[0047] (Step S1 of irradiating laser light) The laser light irradiation step S1 is a step in which the laser irradiation device 201 irradiates the object T with continuous wave laser light B1 in order to 3D model the object T. In step S1 of irradiating the laser beam, the control device 230 controls each part to perform 3D modeling for one layer or multiple layers by irradiating the continuously oscillated continuous wave laser beam B1. That is, in step S1 of irradiating the laser beam, the irradiation control device 231 controls the laser irradiation device 201 to irradiate the continuously oscillated laser beam B1. Also, in step S1 of irradiating the laser beam, the galvanometer mirror control device 232 controls the first galvanometer mirror 204 to perform 3D modeling for one layer or multiple layers.

[0048] (Step S3 of irradiating pulsed laser light) The step S3 of irradiating the pulsed laser light is a step of irradiating the target T with the pulsed laser light B2 from the laser irradiation device 201 in order to generate ultrasonic waves in the target T. In the pulsed laser light irradiation step S3, the pulsed laser light B2 is irradiated onto the object T, and ultrasonic waves are generated by sudden thermal expansion and contraction of the area irradiated with the pulsed laser light B2.

[0049] In step S3 of irradiating the pulsed laser beam, the control device 230 controls each part to irradiate the pulsed laser beam B2 for generating ultrasonic waves in the target object T. That is, in step S3 of irradiating the pulsed laser beam, the irradiation control device 231 controls the laser irradiation device 201 to irradiate the pulsed laser beam B2. Also, in step S3 of irradiating the pulsed laser beam, the galvanometer mirror control device 232 controls the first galvanometer mirror 204 to irradiate the pulsed laser beam B2 to a position where the presence or absence of an internal defect is to be detected.

[0050] The number of times that the pulsed laser beam B2 is irradiated in step S3 of irradiating the pulsed laser beam is one, but it may be multiple times. The irradiated position of the object T with the pulsed laser beam B2 is stationary during the irradiation period of the pulsed laser beam B2. Even if the pulsed laser beam B2 is irradiated multiple times, the irradiated position of the object T with the pulsed laser beam B2 is the same position each time. The beam diameter of the pulsed laser light B2 may be approximately the same as the size S of the internal defect to be detected, for example, several hundred μm. The size of the internal defect here refers to the size of the internal defect when viewed from the surface of the target object T. Note that in order to set the beam diameter of the pulsed laser light B2 to the above size, the defect detection device 200 may be provided with a beam diameter adjustment lens, but it is not essential to provide a beam diameter adjustment lens. The pulse width of the pulsed laser light B2 is preferably not less than 10 ns and not more than 1000 ns.

[0051] In step S3 of irradiating the pulsed laser light, ultrasonic waves can be generated in the object T by irradiating the object T with the pulsed laser light B2 under the irradiation conditions described above. The ultrasonic waves generated in this way are vibrations with a relatively wide band, so even if the natural frequency of the target T differs depending on the distance d from the surface of the target T and the size S of the internal defect, the flexural vibration of this natural frequency can be generated predominantly.

[0052] (Step S5: Measuring Vibration) The vibration measuring step S5 is a step of measuring the vibration of the target object T based on the ultrasonic waves generated by carrying out the pulsed laser light irradiation step S3. Step S5 of measuring the vibration is performed simultaneously with the timing of irradiation with the pulsed laser beam B2 in step S3 of irradiating the pulsed laser beam. In step S5 of measuring the vibration, the detection device 220 causes the vibration measuring device 221 to detect the vibration of the surface of the target object T.

[0053] In the embodiment shown in FIGS. 1, 2, and 3, the vibration of the surface of the target object T based on ultrasonic waves can be detected in a non-contact manner by the laser interferometer 221A or the Doppler vibrometer 221B.

[0054] In the embodiment shown in FIGS. 1, 2, and 3, the vibration of the surface of the target object T based on ultrasonic waves can be detected in a non-contact manner by the laser interferometer 221A or the Doppler vibrometer 221B. In the embodiment shown in Fig. 1, the irradiation position of the pulsed laser beam B2 and the irradiation position of the laser beam B3 are the same. In the embodiment shown in Fig. 2, by controlling the attitude of the galvanometer mirrors 204 and 207, the laser beam B3 can be irradiated to the same position as the irradiation position of the pulsed laser beam B2. Since it is possible to bring the ultrasonic excitation point and the receiving point closer to each other, vibrations on the surface of the object T can be detected even when the inspection surface of the object T is small or when the object T is complex. 1 and 2, if the irradiation position of the pulsed laser beam B2 and the irradiation position of the laser beam B3 are the same position, it is not necessary to consider the vibration transmission time from the irradiation position of the pulsed laser beam B2 to the irradiation position of the laser beam B3, which can reduce the calculation load in step S7 for detecting internal defects, which will be described later.

[0055] 1, the pulsed laser beam B2 and the laser beam B3 can be coaxially irradiated. This makes it possible to detect vibrations on the surface of the object T by preventing the laser beam B3 from being blocked by a part of the object T, even if the object T has a complex structure.

[0056] In the embodiment shown in Fig. 2, the position of the pulsed laser beam B2 and the position of the laser beam B3 can be irradiated so as to always maintain a constant distance between them by controlling the attitude of the galvanometer mirrors 204 and 207. This allows the timing at which noise caused by the irradiation of the pulsed laser beam B2 is detected to be shifted from the timing at which the amplitude at the above-mentioned natural frequency is detected, making it easier to detect the amplitude at the natural frequency. In addition, in the embodiment shown in Fig. 2, by irradiating the positions of the pulsed laser beam B2 and the laser beam B3 so as to always maintain a constant distance between them, the calculation load in step S7 for detecting internal defects, which will be described later, can be reduced compared to the case where the distance between the positions of the pulsed laser beam B2 and the laser beam B3 changes.

[0057] 3, as described above, the irradiation position on the object T of the laser light B3 from the vibration measuring device 221 is a fixed position that is set in advance by adjusting the attitude of the mirror 208. Therefore, the state of the surface of the object T at the irradiation position of the laser light B3 remains unchanged, and therefore the vibration of the surface of the object T can be stably detected. In addition, in the embodiment shown in FIG. 3, since it is not necessary to control the attitude of the second galvanometer mirror 207, the calculation load on the control device 230 can be reduced.

[0058] In this manner, in the defect detection methods according to some embodiments, vibrations on the surface of the target object T may be detected by the laser interferometer 221A or the Doppler vibrometer 221B. This makes it possible to detect the presence or absence of internal defects in a non-contact manner.

[0059] 4 and 5, the contact transducer 221t can directly detect vibrations on the surface of the object T based on ultrasonic waves. This allows the vibrations on the surface of the object T to be detected with better sensitivity than when the laser interferometer 221A or the Doppler vibrometer 221B detects the vibrations on the surface of the object T in a non-contact manner. In the embodiment shown in FIG. 4, the contact transducer 221t is placed on the upper surface of the object T, so that the distance between the irradiation position of the pulsed laser light B2 and the contact transducer 221t can be made relatively close, thereby enabling vibrations on the surface of the object T to be detected with even better sensitivity. In the embodiment shown in Figure 5, the contact transducer 221t is installed on the base plate 301 of the molding apparatus 300, so that vibrations of the object T can be detected even when it is difficult to install the contact transducer 221t on the top surface of the object T, such as when the inspection surface of the object T is small or when the object T is complex.

[0060] (Step S7 to detect internal defects) Step S7 of detecting an internal defect is a step of detecting the presence or absence of an internal defect in the object T based on the vibration measured in step S5 of measuring the vibration. That is, step S7 of detecting an internal defect is a step of detecting the presence or absence of an internal defect in the object T based on the amplitude of a specific frequency component of the vibration of the object T based on ultrasonic waves. 10 is a diagram showing functional blocks of a calculation device 222 related to the process described later in step S7 for detecting an internal defect. The calculation device 222 virtually includes functional blocks of a time waveform accumulation memory 222a, an extraction unit using a window function 222b, an FFT processing unit 222c, an FFT result analysis unit 222d, and a map creation unit (measurement result map creation unit) 222e. In step S7 of detecting an internal defect, the arithmetic device 222 detects the presence or absence of an internal defect in the object T as follows. First, the calculation device 222 acquires, in a time waveform accumulation memory 222a, information on vibrations detected by the vibration measuring device 221 within a preset period following the irradiation timing of the pulsed laser light B2 detected by the photodetector 206, based on the irradiation timing. FIG. 11A is an example of a graph showing the amplitude of vibration obtained from the vibration measuring device 221 as described above.

[0061] Next, the calculation device 222 extracts vibration information required for detecting the presence or absence of an internal defect from the vibration information acquired from the vibration measuring device 221 as described above in the window function extraction section 222b. FIG. 11B is an example of a graph showing vibrations after extracting information required for detecting the presence or absence of an internal defect.

[0062] Specifically, the window function extraction unit 222b extracts vibration information on the first arriving wave from the vibration information acquired from the vibration measuring device 221 as described above. That is, the window function extraction unit 222b extracts vibration information corresponding to the period in which the first arriving wave was detected from the vibration information acquired from the vibration measuring device 221 as described above. In the example shown in Fig. 11B, the window function extraction unit 222b extracts vibration information from the vibration information acquired from the vibration measuring device 221 as described above, assuming that the irradiation timing of the pulsed laser beam B2 detected by the photodetector 206 is 0 seconds, until 5.0 μsec has elapsed since the irradiation timing. The above-mentioned method of extracting information on vibration regarding the first arriving wave is just one example, and information on vibration regarding the first arriving wave may be extracted using other methods. In addition, when extracting information on vibration for 5.0 μs after the irradiation timing, the window function extraction unit 222b excludes information on vibration for a predetermined period after the irradiation timing from the acquisition target in order to remove noise caused by the irradiation of the pulsed laser beam B2. In the example shown in FIG. 11B, the calculation device 222 does not acquire information on vibration for 0.5 μs after the irradiation timing.

[0063] The vibration information about the first arriving wave extracted as described above includes flexural vibration due to a natural frequency caused by the presence of an internal defect near the surface of the target T and a surface wave component. Therefore, the calculation device 222 performs FFT (Fast Fourier Transform) processing on the vibration information about the first arriving wave extracted as described above in the FFT processing unit 222c to extract the flexural vibration due to the natural frequency. FIG. 11C is an example of a graph showing the results of the FFT processing.

[0064] When an internal defect exists in a region relatively close to the surface of the object T, the amplitude of a frequency component that predominates in a relatively low frequency range occurs. This frequency range is determined by the shape of the internal defect, the position of the internal defect, the material of the object T, etc., but may be, for example, in the range of 0.5 MHz to 5.0 MHz. Therefore, the FFT result analysis unit 222d detects an amplitude peak within the above-mentioned relatively low frequency range in the processing result of the above-mentioned FFT processing, and acquires the peak value. If the peak value exceeds a preset threshold, the FFT result analysis unit 222d determines that an internal defect exists directly below the irradiation position of the pulsed laser beam B2. In the example shown in FIG. 11C, a relatively large amplitude peak is observed at 1.20 MHz. The FFT result analysis unit 222d may determine the presence or absence of an internal defect based on the sum of the results of the FFT processing in the FFT processing unit 222c, an FFT amplitude value at a specific frequency, or the like.

[0065] Thus, in the defect detection method according to the embodiment described above, in step S7 of detecting internal defects, the presence or absence of an internal defect in the object T can be detected based on frequency components determined by the shape of the internal defect, the position of the internal defect, the material of the object T, etc. This makes it possible to detect the presence or absence of internal defects in a region of the object T that is relatively close to the surface.

[0066] In addition, the calculation device 222, in cooperation with the control device 230, repeatedly performs the above-mentioned steps from step S1 of irradiating the laser light to step S7 of detecting internal defects while shifting the irradiation position of the pulsed laser light B2, thereby detecting the presence or absence of internal defects in areas relatively close to the surface over the entire surface of the object T.

[0067] The calculation device 222 creates a map indicating the relationship between the positions on the surface of the target object T and the peak values ​​acquired by the FFT result analysis unit 222d in the map creation unit 222e. That is, the map creation unit 222e creates the map by plotting the FFT processing result values ​​in a map form. Fig. 12 is a diagram showing an example of the map created by the map creation unit 222e. In the map shown in Fig. 12, the distribution of the peak values ​​is represented by a density corresponding to the peak values. For example, in the map shown in Fig. 12, it can be inferred that an internal defect exists at the position surrounded by the dashed line. When the FFT result analysis unit 222d acquires the sum of the results of the FFT processing in the FFT processing unit 222c, the map creation unit 222e creates a map indicating the relationship between this sum and the position on the surface of the target object T. Furthermore, when the FFT result analysis unit 222d acquires an FFT amplitude value of a specific frequency, the map creation unit 222e creates a map indicating the relationship between this FFT amplitude value and the position on the surface of the target object T.

[0068] (Step S9 of repairing internal defects) Step S9 of repairing internal defects is a step in which, when an internal defect is detected in an object T being 3D printed by additive manufacturing, the next layer and up to a few layers below the next layer are melted so as to repair the internal defect when the next layer is formed directly above the internal defect. In the defect detection method according to some embodiments, if the presence of an internal defect is detected in step S7 of detecting an internal defect, step S9 of repairing the internal defect is performed. That is, in some embodiments, when an internal defect is detected in an object T being 3D printed by additive manufacturing, the next layer and layers several layers below the next layer may be melted so as to repair the internal defect when the next layer is formed directly above the internal defect. "Melting the next layer and layers several layers below the next layer" means melting the layer including the internal defect together with the upper layer located above the internal defect.

[0069] For example, if an internal defect occurs during the second 3D printing from the left shown in Figure 6 (step S1 of irradiating laser light), and the presence of an internal defect is detected in the subsequent step S7 of detecting internal defects, then during the next 3D printing, the third 3D printing from the left (step S1 of irradiating laser light), the output of the continuous wave laser light B1 can be made greater than the output in normal 3D printing, and 3D printing (step S9 of repairing the internal defect) can be performed.

[0070] The defect detection method according to the embodiment described above includes step S1 of irradiating laser light, step S3 of irradiating pulsed laser light, step S5 of measuring vibration, and step S7 of detecting internal defects. This allows the same laser irradiation device 201 to irradiate the object T with laser light (continuous wave laser light B1 or pulsed laser light B4) for 3D printing and the object T with pulsed laser light (pulsed laser light B2 or pulsed laser light B4) for generating ultrasonic waves in the object T, thereby reducing the number of devices to be controlled. This makes it difficult to control the devices, and therefore provides a defect detection method suitable for detecting internal defects in the object T to be 3D printed.

[0071] (When detecting internal defects while 3D printing object T) FIG. 13 is a flowchart showing a procedure for carrying out a process for detecting 3D modeling and internal defects by the second method described above. The defect detection method shown in FIG. 13 includes step S13 of irradiating a pulsed laser beam, step S15 of measuring vibration, step S17 of detecting an internal defect, and step S19 of repairing the internal defect.

[0072] (Step S13 of irradiating pulsed laser light) The step S13 of irradiating the pulsed laser beam is a step of irradiating the object T with the pulsed laser beam B4 from the laser irradiation device 201 in order to 3D model the object T and generate ultrasonic waves in the object T at the same time. In step S13 of irradiating the pulsed laser light, the pulsed laser light B4 is irradiated onto the powder bed, and 3D modeling is performed by irradiating the pulsed laser light B4, while ultrasonic waves are generated by sudden thermal expansion and contraction of the area irradiated with the pulsed laser light B4.

[0073] In step S13 of irradiating the pulsed laser beam, the control device 230 controls each part to 3D-print the object T and at the same time irradiate the object T with a pulsed laser beam B4 for generating ultrasonic waves in the object T. That is, in step S13 of irradiating the pulsed laser beam, the irradiation control device 231 controls the laser irradiation device 201 to irradiate the pulsed laser beam B4. Also, in step S13 of irradiating the pulsed laser beam, the galvanometer mirror control device 232 controls the first galvanometer mirror 204 to irradiate the pulsed laser beam B4 to a position where 3D printing and the presence or absence of internal defects are to be detected.

[0074] The number of times that the pulsed laser light B4 is irradiated in step S13 for irradiating the pulsed laser light is one for each position where the 3D modeling and the presence or absence of internal defects are to be detected, but it may be multiple times. The irradiated position of the target T with the pulsed laser light B4 is stationary during the irradiation period of the pulsed laser light B4. Even if the number of times that the pulsed laser light B4 is irradiated for each position is multiple, the irradiated position of the target T with the pulsed laser light B4 for each irradiation is the same position. The beam diameter of the pulsed laser light B4 may be approximately the same as the size S of the internal defect to be detected, for example, several hundred μm. The size of the internal defect here refers to the size of the internal defect when viewed from the surface of the target object T. Note that in order to set the beam diameter of the pulsed laser light B4 to the above size, the defect detection device 200 may be provided with a beam diameter adjustment lens, but it is not essential to provide a beam diameter adjustment lens. The pulse width of the pulsed laser light B4 is preferably 10 nsec or more and 1000 nsec or less.

[0075] In step S13 of irradiating the pulsed laser light, by irradiating the target T with the pulsed laser light B4 under the irradiation conditions described above, it is possible to melt the raw material powder 303 and generate ultrasonic waves in the target T. The ultrasonic waves generated in this way are vibrations with a relatively wide band, so even if the natural frequency of the target T differs depending on the distance d from the surface of the target T and the size S of the internal defect, it is possible to generate flexural vibrations of this natural frequency prominently.

[0076] (Step S15: Measuring Vibration) The vibration measuring step S15 is a step of measuring the vibration of the object based on the ultrasonic waves generated by carrying out the pulsed laser light irradiating step S13. Step S15 of measuring the vibration is performed at approximately the same time as the timing of irradiation with the pulsed laser beam B4 in step S13 of irradiating the pulsed laser beam. In step S15 of measuring the vibration, the detection device 220 causes the vibration measuring device 221 to detect the vibration of the surface of the target object T.

[0077] In the embodiment shown in FIGS. 1, 2, and 3, the vibration of the surface of the target object T based on ultrasonic waves can be detected in a non-contact manner by the laser interferometer 221A or the Doppler vibrometer 221B.

[0078] In the embodiment shown in FIGS. 1, 2, and 3, the vibration of the surface of the target object T based on ultrasonic waves can be detected in a non-contact manner by the laser interferometer 221A or the Doppler vibrometer 221B. In the embodiment shown in Fig. 1, the irradiation position of the pulsed laser beam B4 and the irradiation position of the laser beam B3 are the same position. In the embodiment shown in Fig. 2, by controlling the attitude of the galvanometer mirrors 204 and 207, the laser beam B3 can be irradiated to the same position as the irradiation position of the pulsed laser beam B4. Since it is possible to bring the ultrasonic excitation point and the receiving point closer to each other, vibrations on the surface of the object T can be detected even when the inspection surface of the object T is small or when the object T is complex. 1 and 2, if the irradiation position of the pulsed laser beam B4 and the irradiation position of the laser beam B3 are the same position, it is not necessary to consider the vibration transmission time from the irradiation position of the pulsed laser beam B4 to the irradiation position of the laser beam B3, which reduces the computation load in step S17 for detecting internal defects, which will be described later.

[0079] 1, the pulsed laser beam B4 and the laser beam B3 can be coaxially irradiated. This makes it possible to detect vibrations on the surface of the object T by preventing the laser beam B3 from being blocked by a part of the object T, even if the object T has a complex structure.

[0080] In the embodiment shown in Fig. 2, the position of the pulsed laser beam B4 and the position of the laser beam B3 can be irradiated so as to always maintain a constant distance between them by controlling the attitude of the galvanometer mirrors 204 and 207. This allows the timing at which noise caused by the irradiation of the pulsed laser beam B4 is detected to be shifted from the timing at which the amplitude at the above-mentioned natural frequency is detected, making it easier to detect the amplitude at the natural frequency. In addition, in the embodiment shown in Fig. 2, by irradiating so that the position of the pulsed laser beam B4 and the position of the laser beam B3 are irradiated so as to always maintain a constant distance between them, the calculation load in step S17 for detecting internal defects, which will be described later, can be reduced compared to the case where the distance between the position of the pulsed laser beam B4 and the position of the laser beam B3 changes.

[0081] 3, as described above, the irradiation position on the object T of the laser light B3 from the vibration measuring device 221 is a fixed position that is set in advance by adjusting the attitude of the mirror 208. Therefore, the state of the surface of the object T at the irradiation position of the laser light B3 remains unchanged, and therefore the vibration of the surface of the object T can be stably detected. In addition, in the embodiment shown in FIG. 3, since it is not necessary to control the attitude of the second galvanometer mirror 207, the calculation load on the control device 230 can be reduced.

[0082] In this manner, in the defect detection methods according to some embodiments, vibrations on the surface of the target object T may be detected by the laser interferometer 221A or the Doppler vibrometer 221B. This makes it possible to detect the presence or absence of internal defects in a non-contact manner.

[0083] 4 and 5, the contact transducer 221t can directly detect vibrations on the surface of the object T based on ultrasonic waves. This allows the vibrations on the surface of the object T to be detected with better sensitivity than when the laser interferometer 221A or the Doppler vibrometer 221B detects the vibrations on the surface of the object T in a non-contact manner. In the embodiment shown in FIG. 4, the contact transducer 221t is placed on the upper surface of the object T, so that the distance between the irradiation position of the pulsed laser light B4 and the contact transducer 221t can be made relatively close, thereby enabling vibrations on the surface of the object T to be detected with even better sensitivity. In the embodiment shown in Figure 5, the contact transducer 221t is installed on the base plate 301 of the molding apparatus 300, so that vibrations of the object T can be detected even when it is difficult to install the contact transducer 221t on the top surface of the object T, such as when the inspection surface of the object T is small or when the object T is complex.

[0084] (Step S17 for detecting internal defects) Step S17 of detecting an internal defect is a step of detecting the presence or absence of an internal defect in the object based on the vibration measured in step S15 of measuring the vibration. That is, step S17 of detecting an internal defect is a step of detecting the presence or absence of an internal defect in the object T based on the amplitude of a specific frequency component of the vibration of the object T based on ultrasonic waves. In step S17 for detecting an internal defect, the arithmetic device 222 detects the presence or absence of an internal defect in the object T as follows. First, the calculation device 222 acquires, in the time waveform accumulation memory 222a, information on vibrations detected by the vibration measuring device 221 within a preset period following the irradiation timing of the pulsed laser light B4 detected by the photodetector 206, based on the irradiation timing.

[0085] Next, the calculation device 222 extracts vibration information required for detecting the presence or absence of an internal defect from the vibration information acquired from the vibration measuring device 221 as described above in the window function extraction unit 222b. The contents of the process in the window function extraction unit 222b are substantially the same as the contents of the process in step S7 for detecting an internal defect in the first method shown in Fig. 8, so a detailed description will be omitted. Note that the window function extraction unit 222b extracts vibration information from the irradiation timing of the pulsed laser light B4 detected by the photodetector 206 up to 5.0 μsec after the irradiation timing, assuming that the irradiation timing is 0 seconds.

[0086] Next, the arithmetic device 222 performs FFT processing on the vibration information regarding the first arriving wave extracted as described above in order to extract the flexural vibration due to the natural frequency in the FFT processing section 222c.

[0087] The content of the processing performed by the FFT result analysis unit 222d based on the results of the above-mentioned FFT processing is the same as the content of the processing in step S7 for detecting internal defects in the first method shown in FIG. 8, so a detailed description thereof will be omitted.

[0088] Thus, in the defect detection method according to the embodiment described above, in step S17 for detecting internal defects, the presence or absence of an internal defect in the object T can be detected based on frequency components determined by the shape of the internal defect, the position of the internal defect, the material of the object T, etc. This makes it possible to detect the presence or absence of internal defects in a region of the object T that is relatively close to the surface.

[0089] In addition, the calculation device 222, in cooperation with the control device 230, repeatedly performs the steps from step S13 of irradiating the pulsed laser light described above to step S17 of detecting internal defects while shifting the irradiation position of the pulsed laser light B4, thereby detecting the presence or absence of internal defects in areas relatively close to the surface over the entire surface of the object T.

[0090] The calculation device 222 creates a map showing the relationship between the positions on the surface of the target object T and the peak values ​​acquired by the FFT result analysis unit 222d in the map creation unit 222e. That is, the map creation unit 222e creates the map by plotting the FFT processing result values ​​in a map form. The content of the process performed by the map creation unit 222e is the same as the content of the process in step S7 for detecting internal defects in the first method shown in Fig. 8, so a detailed description will be omitted.

[0091] (Step S19 of repairing internal defects) Step S19 of repairing internal defects is a step in which, when an internal defect is detected in an object T being 3D-modeled by additive manufacturing, at least the portion of the object T located directly above the internal defect is melted to repair the internal defect. In the defect detection method according to some embodiments, if the presence of an internal defect is detected in step S17 of detecting an internal defect, step S19 of repairing the internal defect is performed. That is, in some embodiments, when an internal defect is detected in the object T being 3D printed by stacking additive printing, the next layer and layers several layers below the next layer may be melted so as to repair the internal defect when the next layer is formed directly above the internal defect. In this case, the output of the pulsed laser beam B4 may be increased to be greater than that in normal 3D printing to perform 3D printing (step S19 of repairing the internal defect). Furthermore, in some embodiments of the defect detection method, when the presence of an internal defect is detected in step S17 for detecting the internal defect, the pulsed laser light B4 may be irradiated again at a higher output than that used in normal 3D printing without changing the irradiation position of the pulsed laser light B4 to melt at least the portion of the target object T located directly above the internal defect, thereby repairing the internal defect (see FIG. 7).

[0092] The defect detection method according to the embodiment described above includes step S13 of irradiating a pulsed laser beam, step S15 of measuring vibration, and step S19 of repairing the internal defect. According to the defect detection method of the embodiment described above, ultrasonic waves can be generated in the object T at the same time as 3D printing the object T, so that 3D printing of the object T and detection of the presence or absence of an internal defect in the object T can be performed simultaneously. This makes it possible to shorten the time required for 3D printing of the object T and detection of the presence or absence of an internal defect in the object T, so that a defect detection method suitable for detecting internal defects in an object T to be 3D printed can be provided.

[0093] The present disclosure is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0094] The contents described in each of the above embodiments can be understood, for example, as follows. (1) A defect detection device 200 according to at least one embodiment of the present disclosure includes a laser irradiation device 201 capable of irradiating a laser beam (continuous wave laser beam B1 or pulsed laser beam B4) to 3D-print an object T and irradiating a pulsed laser beam (pulsed laser beam B2 or pulsed laser beam B4) to the object T to generate ultrasonic waves in the object T. The defect detection device 200 according to at least one embodiment of the present disclosure includes an irradiation control device 231 that controls irradiation of the laser beam. The defect detection device 200 according to at least one embodiment of the present disclosure includes a vibration measuring device 221 configured to measure vibration of the object T based on ultrasonic waves. The defect detection device 200 according to at least one embodiment of the present disclosure includes a detection device 220 (a calculation device 222) configured to detect the presence or absence of an internal defect in the object T based on the vibration detected by the vibration measuring device 221.

[0095] According to the configuration of (1) above, the laser beam (continuous wave laser beam B1 or pulsed laser beam B4) for 3D printing of the object T and the pulsed laser beam (pulsed laser beam B2 or pulsed laser beam B4) for irradiating the object T to generate ultrasonic waves in the object T can be irradiated by the same laser irradiation device 201, which simplifies the device configurations of the defect detection device 200 and the 3D printing device 300. This makes it possible to provide the defect detection device 200 suitable for detecting internal defects of the object T to be 3D printed.

[0096] (2) In some embodiments, in the configuration of (1) above, the irradiation control device 231 may be configured to control the laser irradiation device 201 to irradiate the object T with a continuous wave laser light (continuous wave laser light B1) in order to 3D model the object T.

[0097] According to the above configuration (2), by using a continuous wave laser light (continuous wave laser light B1) for 3D printing the object T and a pulsed laser light (pulsed laser light B2) for generating ultrasonic waves in the object T, it is possible to irradiate the laser light under more suitable conditions for each of the cases of 3D printing the object T and generating ultrasonic waves in the object T.

[0098] (3) In some embodiments, in the configuration of (1) above, the irradiation control device 231 may be configured to control the laser irradiation device 201 to irradiate a pulsed laser beam (pulsed laser beam B4) to 3D print an object.

[0099] According to the above configuration (3), if ultrasonic waves are generated in the object T by irradiating the object T with a pulsed laser beam (pulsed laser beam B4) in order to 3D print the object T, it is possible to simultaneously perform 3D printing of the object T and detection of the presence or absence of internal defects in the object T. This makes it possible to shorten the time required for 3D printing of the object T and detection of the presence or absence of internal defects in the object T.

[0100] (4) In some embodiments, in any of the configurations (1) to (3) above, a first galvanometer mirror 204 may be provided for scanning a laser light (continuous wave laser light B1 or pulsed laser light B4) for 3D modeling the object T.

[0101] According to the above configuration (4), since there is no need to move the laser irradiation device 201 itself, the mechanism for performing scanning with the laser light can be made compact.

[0102] (5) In some embodiments, in any of the configurations (1) to (4) above, the vibration measuring device 221 may include either a laser interferometer 221A or a Doppler vibrometer 221B.

[0103] According to the above configuration (5), the vibration of the target object T can be measured in a non-contact manner.

[0104] (6) In some embodiments, the configuration of (5) above may further include a second galvanometer mirror 207 for scanning the measurement laser light (laser light B3) from the laser interferometer 221A or the Doppler vibrometer 221B.

[0105] According to the above configuration (6), since the measurement laser light (laser light B3) can be scanned, the measurement laser light (laser light B3) can be irradiated to the same position as the irradiation position of the pulsed laser light B2 or the pulsed laser light B4.

[0106] (7) In some embodiments, in any of the configurations (1) to (3) above, the vibration measuring device 221 may include either a laser interferometer 221A or a Doppler vibrometer 221B, and the irradiation control device 231 may have a laser light (continuous wave laser light B1 or pulsed laser light B4) for 3D printing the object T, and a galvanometer mirror (first galvanometer mirror 204) for scanning the measurement laser light (laser light B3) from the laser interferometer 221A or the Doppler vibrometer 221B.

[0107] According to the configuration of (7) above, scanning of the laser light (continuous wave laser light B1 or pulsed laser light B4) for 3D printing of the object T and scanning of the measurement laser light (laser light B3) from the laser interferometer 221A or the Doppler vibrometer 221B can be performed by controlling the same galvanometer mirror (first galvanometer mirror 204). This allows the defect detection device 200 to be simplified compared to a case in which scanning of the laser light (continuous wave laser light B1 or pulsed laser light B4) for 3D printing of the object T and scanning of the measurement laser light (laser light B3) from the laser interferometer 221A or the Doppler vibrometer 221B are performed by separate galvanometer mirrors.

[0108] (8) In some embodiments, in any of the configurations (1) to (4) above, the vibration measuring device 221 may include a contact transducer 221t for measuring vibrations of the object T based on ultrasonic waves.

[0109] According to the above configuration (8), the measurement accuracy can be improved more easily than in the case where the vibration of the target object T based on ultrasonic waves is measured in a non-contact manner.

[0110] (9) A defect detection method according to at least one embodiment of the present disclosure includes a step (S1) of irradiating laser light (continuous wave laser light B1) from a laser irradiation device 201 to 3D print an object T, a step (S3) of irradiating pulsed laser light (pulsed laser light B2) from the laser irradiation device 201 to the object T to generate ultrasonic waves in the object T, a step (S5) of measuring vibrations of the object T based on the ultrasonic waves, and a step (S7) of detecting the presence or absence of an internal defect in the object T based on the measured vibrations.

[0111] According to the method of (9) above, the laser light (continuous wave laser light B1) for 3D printing of the object T and the pulsed laser light (pulsed laser light B2) for irradiating the object T to generate ultrasonic waves in the object T can be irradiated by the same laser irradiation device 201, so that the number of devices to be controlled can be reduced. This makes it difficult to control the devices, and therefore it is possible to provide a defect detection method suitable for detecting internal defects of the object T to be 3D printed.

[0112] (10) A defect detection method according to at least one embodiment of the present disclosure includes a step (S13) of irradiating the object T with pulsed laser light (pulsed laser light B4) from the laser irradiation device 201 in order to 3D print the object T and simultaneously generate ultrasonic waves in the object T, a step (S15) of measuring vibrations of the object T based on ultrasonic waves, and a step (S17) of detecting the presence or absence of an internal defect in the object T based on the measured vibrations.

[0113] According to the method (10) above, ultrasonic waves can be generated in the object T at the same time as 3D printing the object T, so that 3D printing of the object T and detection of the presence or absence of internal defects in the object T can be performed simultaneously. This shortens the time required for 3D printing of the object T and detection of the presence or absence of internal defects in the object T, so that a defect detection method suitable for detecting internal defects in the object T to be 3D printed can be provided. [Explanation of symbols]

[0114] 200 Defect detection device 201 Laser irradiation device 204 Galvanometer Mirror (First Galvanometer Mirror) 207 Galvanometer Mirror (Second Galvanometer Mirror) 220 Detection Device 221 Vibration Measuring Device 221A Laser Interferometer 221B Doppler Vibrometer 221D Data Logger 221t Contact Transducer 222 Arithmetic equipment 230 Control device 231 Irradiation Control Device 232 Galvano mirror control device 300 Modeling equipment

Claims

1. A laser irradiation device capable of irradiating a laser beam to melt and solidify a raw material powder to form an object in 3D, and capable of irradiating a pulsed laser beam onto the object to generate ultrasonic waves in the object; an irradiation control device for controlling the irradiation of the laser light; a vibration measuring device configured to measure vibration of the object based on the ultrasonic waves; a detection device configured to detect the presence or absence of an internal defect of the object based on the vibration detected by the vibration measuring device; and A defect detection device comprising:

2. The irradiation control device controls the laser irradiation device to irradiate the object with a continuous wave laser beam in order to 3D model the object. The defect detection device according to claim 1 .

3. The irradiation control device controls the laser irradiation device to irradiate the object with a pulsed laser beam in order to 3D model the object. The defect detection device according to claim 1 .

4. A first galvanometer mirror is provided for scanning a laser beam for 3D modeling the object. The defect detection device according to any one of claims 1 to 3.

5. The vibration measuring device includes either a laser interferometer or a Doppler vibrometer.

5. The defect detection device according to claim 1.

6. A second galvanometer mirror is provided for scanning the measurement laser light from the laser interferometer or the Doppler vibrometer. The defect detection device according to claim 5.

7. the vibration measuring device includes one of a laser interferometer or a Doppler vibrometer, The irradiation control device has a laser light for 3D printing of the object and a galvanometer mirror for scanning the laser light for measurement from the laser interferometer or the Doppler vibrometer. The defect detection device according to any one of claims 1 to 3.

8. The vibration measuring device includes a contact transducer for measuring vibration of the object based on the ultrasonic waves.

5. The defect detection device according to claim 1.

9. A step of irradiating a laser beam from a laser irradiation device to 3D model an object; irradiating the target with pulsed laser light from the laser irradiation device to generate ultrasonic waves in the target; measuring vibration of the object based on the ultrasonic waves; detecting the presence or absence of an internal defect of the object based on the measured vibration; A defect detection method comprising:

10. irradiating a pulsed laser beam from a laser irradiation device onto an object in order to 3D model the object and generate ultrasonic waves in the object at the same time; measuring vibration of the object based on the ultrasonic waves; detecting the presence or absence of an internal defect of the object based on the measured vibration; A defect detection method comprising:

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