Three-dimensional additive manufacturing evaluation system and three-dimensional additive manufacturing evaluation method

Abstract

This three-dimensional additive manufacturing evaluation system is provided with: a radiation device that is configured so as to radiate a beam for melting a powder layer that has been laid; a scanning device for reflecting the beam from the radiation device toward the powder layer and moving the beam irradiation position in the powder layer by altering the reflection angle of the beam; a photometry device for measuring the intensity of light emitted from a melt pool formed at the irradiation position in the powder layer; a reflection device that is disposed between the scanning device and the radiation device and is configured so as to reflect emitted light reflected by the scanning device toward the photometry device; and a first focus position alteration device that includes a first lens disposed between the reflection device and the photometry device and that is configured so as to move the first lens in a first optical axis direction that is the direction of the optical axis of the first lens.

Description

Three-dimensional additive manufacturing evaluation system and three-dimensional additive manufacturing evaluation method

[0001] This application claims priority to Japanese Patent Application No. 2023-199534, filed with the Japan Patent Office on November 27, 2023, the contents of which are incorporated herein by reference.

[0002] Conventionally, three-dimensional printing apparatuses that form a model by irradiating a beam onto a laid powder layer have been known. For example, the three-dimensional printing apparatus disclosed in Patent Document 1 includes a laser for irradiating a powder-laying surface (build surface) with a laser beam. The irradiated laser beam passes through a focusing system and is projected onto the powder-laying surface. Light energy, such as that emitted by a molten pool formed on the powder-laying surface, passes through the focusing system and a partially reflecting mirror and is incident on an on-axis optical sensor. Data generated by the on-axis optical sensor is used to determine the thermal energy density during the build process.

[0003] Special Publication No. 2023-531178

[0004] In the above-mentioned three-dimensional modeling device, when the projection position on the powder-laid surface moves, the optical path length from the molten pool to the axial optical sensor changes. In this case, the light emitted from the molten pool may not be collected by the axial optical sensor, and the thermal energy density in the molten pool may not be measured accurately. Therefore, there is a risk that the quality of the molten pool may not be accurately evaluated. To cite a more specific example, in the above-mentioned three-dimensional modeling device, the light from the metal plume directly above the molten pool may be collected by the axial optical sensor, and there is a risk that an abnormality in the molten pool may not be accurately evaluated.

[0005] An object of the present disclosure is to provide a three-dimensional additive manufacturing evaluation system and a three-dimensional additive manufacturing evaluation method that can accurately evaluate the quality of a molten pool.

[0006] A three-dimensional additive manufacturing evaluation system according to at least one embodiment of the present disclosure comprises: an irradiation device configured to irradiate a beam for melting a laid powder layer; a scanning device for reflecting the beam from the irradiation device toward the powder layer and changing the reflection angle of the beam to move the irradiation position of the beam on the powder layer; an optical measurement device for measuring the intensity of light emitted from a molten pool formed at the irradiation position of the powder layer; a reflection device arranged between the scanning device and the irradiation device and configured to reflect the light reflected by the scanning device toward the optical measurement device; and a first focusing position changing device including a first lens arranged between the reflection device and the optical measurement device and configured to move the first lens in a first optical axis direction that is the optical axis direction of the first lens.

[0007] A three-dimensional additive manufacturing evaluation method according to at least one embodiment of the present disclosure includes: a measurement step of measuring the intensity of light emitted from a molten pool formed at a position where the beam is irradiated in a powder layer using an optical measurement device; and a first lens movement step of moving a first lens, which is disposed between a reflection device that reflects the light emitted toward the optical measurement device and the optical measurement device, in a first optical axis direction, which is the optical axis direction of the first lens, according to the irradiation position in the powder layer, during the measurement step.

[0008] According to the present disclosure, it is possible to provide a three-dimensional additive manufacturing evaluation system and a three-dimensional additive manufacturing evaluation method that can accurately evaluate the quality of a molten pool.

[0009] Fig. 1 is a schematic diagram of a three-dimensional additive manufacturing apparatus according to one embodiment; Fig. 2 is a schematic diagram of a three-dimensional additive manufacturing evaluation system according to one embodiment; Fig. 3 is a schematic diagram showing a beam irradiation position on a powder layer according to one embodiment; Fig. 4 is a schematic diagram of a controller according to one embodiment; Fig. 5 is a flowchart of a three-dimensional additive manufacturing evaluation method according to one embodiment.

[0010] Several embodiments of the present disclosure will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure and are merely illustrative examples. For example, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express relative displacements with a tolerance or angle or distance to the extent that the same function is achieved. For example, expressions expressing the equality of things, such as "same," "equal," and "homogeneous," not only express strict equality, but also express tolerance or differences to the extent that the same function is achieved. For example, expressions expressing shapes such as a square or cylindrical shape not only express shapes such as a square or cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is achieved. On the other hand, the expressions "comprise," "include," or "have" one component are not exclusive expressions that exclude the existence of other components. Note that similar components may be assigned the same reference numerals and descriptions thereof may be omitted.

[0011] 1 is a schematic diagram of a 3D additive manufacturing apparatus 1 according to an embodiment of the present disclosure. The 3D additive manufacturing apparatus 1 includes a powder supplying device 3 for laying down powder that will be the raw material for a 3D object, an irradiation device 4 for irradiating the powder with a beam that melts it, a scanning device 30 for reflecting the beam irradiated from the irradiation device 4 toward a powder layer 6 made of the laid down powder, and a base plate 9 that can be raised and lowered.

[0012] The powder supply device 3 is configured to move horizontally. The irradiation device 4 is fixed above a base plate 9. The scanning device 30 includes at least one mirror for reflecting the beam, an actuator for rotating the mirror, and a control driver for sending a drive command to the actuator. The actuator rotates the mirror in accordance with the drive command sent from the control driver, and the scanning device 30 changes the reflection angle of the beam.

[0013] As a more detailed example, the scanning device 30 is a galvanometer scanner. The mirror has an X mirror configured to rotate about the X axis, and a Y mirror configured to rotate about the Y axis. Both the X axis and the Y axis are horizontal axes. The actuator has an X motor and a Y motor for applying rotational power to the X mirror and the Y mirror, respectively. The galvanometer scanner changes the reflection angle of the beam by driving the X motor and the Y motor in accordance with drive commands sent from a control driver serving as a motor driver.

[0014] The operation of the 3D additive manufacturing apparatus 1 to form a model is outlined below. The powder supplying device 3 forms the first powder layer 6 by laying powder on the base plate 9 while moving horizontally. The irradiation device 4 then irradiates a beam toward the scanning device 30, which reflects the beam toward the powder layer 6. The powder layer 6 irradiated with the beam melts. The scanning device 30 changes the beam reflection angle, so that the area irradiated with the beam (spot) moves across the entire first powder layer 6. The portions of the powder layer 6 that have been irradiated with the beam solidify sequentially, forming the first modeling layer 7. The irradiation device 4 stops irradiating the beam, and the base plate 9 descends a distance equivalent to the thickness of the modeling layer 7.

[0015] The powder supplying device 3 then lays powder on the first modeling layer 7 to form a second powder layer 6, and the scanning device 30 reflects the beam emitted from the irradiation device 4 toward the second powder layer 6. After the second modeling layer 7 is formed, the base plate 9 descends again. The powder supplying device 3, irradiation device 4, scanning device 30, and base plate 9 repeat the above operations to form a model as stacked modeling layers 7. In the schematic diagram of FIG. 1 , a third powder layer 6 is laid on top of the second modeling layer 7.

[0016] The powder supplied by the powder supplying device 3 may be a metal material such as iron, copper, aluminum, or titanium, or a non-metal material such as ceramic. The beam irradiated by the irradiation device 4 may be either a laser beam or an electron beam.

[0017] <Basic Configuration of 3D Additive Manufacturing Evaluation System 5> Figure 2 is a schematic diagram showing a 3D Additive Manufacturing evaluation system 5 according to an embodiment of the present disclosure. A molten pool 8 is formed in the powder layer 6 at an irradiation position P on the powder layer 6 where a beam from the irradiation device 4 strikes, and the molten pool 8 solidifies to form a model layer 7. The 3D Additive Manufacturing evaluation system 5 is configured to evaluate the quality of the molten pool 8, and the irradiation device 4 and the scanning device 30 described above are both components of the 3D Additive Manufacturing evaluation system 5. Note that the molten pool 8 may include a molten portion of the model layer 7 located directly below the powder layer 6.

[0018] The three-dimensional additive manufacturing evaluation system 5 includes an optical measurement device 80 for measuring the intensity of light emitted from the molten pool 8 (hereinafter, the light emitted from the molten pool 8 may be simply referred to as "light emission"). The scattered light is indicated by arrow S in FIG. 2. The optical measurement device 80 includes a light receiving unit configured to receive at least a portion of the light reaching the scanning device 30, and an analysis unit configured to analyze the intensity of the light received by the light receiving unit. As a more specific example, the light receiving unit is a photodiode fixed at a predetermined position. The analysis unit is a calculation device configured to calculate the intensity of the light emission based on the electrical signal output from the photodiode.

[0019] The three-dimensional additive manufacturing evaluation system 5 further includes a reflecting device 40 disposed on the beam path between the scanning device 30 and the irradiation device 4. The reflecting device 40 includes a half mirror, which may be a dichroic mirror or the like. The half mirror is configured to allow the beam from the irradiation device 4 to pass toward the scanning device 30, and is configured to reflect the emitted light reflected by the scanning device 30 toward the optical measurement device 80. A portion of the emitted light from the molten pool 8 formed in the powder layer 6 by irradiation with the beam reaches the scanning device 30, and the emitted light passes through the mirror of the scanning device 30 and the half mirror of the reflecting device 40 in this order and reaches the light receiving unit of the optical measurement device 80.

[0020] The intensity of the emitted light needs to be measured accurately in order to accurately evaluate the quality of the molten pool 8. To this end, it is preferable that the emitted light that passes through the scanning device 30 and the reflecting device 40 in this order is collected at the light receiving portion of the optical measuring device 80.

[0021] 3, when the irradiation position P moves horizontally (arrow H) by changing the beam reflection angle using the scanning device 30, the optical path length (dimension L) of the emitted light between the irradiation position P and the optical measurement device 80 changes. Conventionally, when the dimension L increases, the emitted light scattered at the irradiation position P becomes concentrated in front of the light receiving unit of the optical measurement device 80. Instead, the light emitted by the plume formed directly above the molten pool 8 (arrow Q) becomes concentrated at the light receiving unit. This makes it difficult to accurately measure the intensity of the emitted light.

[0022] 2 , the 3D additive manufacturing evaluation system 5 according to this embodiment further includes a first focus position changing device 10 including a first lens 11 disposed between the reflecting device 40 and the optical measurement device 80. The first focus position changing device 10 is configured to move the first lens 11 along the optical axis direction (first optical axis direction) of the first lens 11. As a more specific example, the first focus position changing device 10 further includes a first motor 101 for moving the first lens 11. The first optical axis direction is the vertical direction.

[0023] The three-dimensional additive manufacturing evaluation system 5 according to an embodiment of the present disclosure further includes a first condenser lens 13 fixed between the first lens 11 and the reflecting device 40. The first lens 11 also includes a first diffusing lens 11a. The focal length of the first condenser lens 13 changes when the first motor 101 moves the first diffusing lens 11a in the first optical axis direction.

[0024] With the above configuration, when the irradiation position P moves horizontally, the first focusing position changing device 10 can move the first lens 11 in the first optical axis direction. Because the focal length of the first focusing lens 13 changes, even if the optical path length (dimension L in FIG. 3 ) between the irradiation position P and the optical measurement device 80 changes, the light emitted from the molten pool 8 remains focused at the light receiving unit of the optical measurement device 80. More specifically, even if the dimension L shown in FIG. 3 increases, the light emitted from the plume is less likely to be focused at the light receiving unit of the optical measurement device 80, and the light emitted remains focused at the light receiving unit. This provides a 3D additive manufacturing evaluation system 5 capable of accurately evaluating the quality of the molten pool 8.

[0025] The first focusing position changing device 10 according to the embodiment of the present disclosure may be a 3D scanner, and the first lens 11 may include a plurality of first diverging lenses 11 a. The first focusing position changing device 10 may further include an objective lens 15 fixed between the first lens 11 and the first focusing lens 13.

[0026] The optical path of the light emitted from the molten pool 8 between the scanning device 30 and the irradiation device 4 is also the path of the beam emitted by the irradiation device 4. In other words, the dimension L shown in FIG. 3 also corresponds to the beam path length between the scanning device 30 and the irradiation device 4.

[0027] <Details of the Optical System of the 3D Additive Manufacturing Evaluation System 5> With reference to Fig. 2, a configuration that may be additionally provided in the 3D Additive Manufacturing evaluation system 5 will be described. The 3D Additive Manufacturing evaluation system 5 further includes a second focusing position changing device 20 including a second lens 22 arranged on the beam path between the reflecting device 40 and the irradiating device 4. The second focusing position changing device 20 is configured to move the second lens 22 along the optical axis direction of the second lens 22 (second optical axis direction). As a more specific example, the second focusing position changing device 20 further includes a second motor 102 for moving the second lens 22. Note that the second optical axis direction is perpendicular to the first optical axis direction.

[0028] The three-dimensional additive manufacturing evaluation system 5 according to an embodiment of the present disclosure further includes a second condenser lens 23 fixed between the second lens 22 and the reflecting device 40. The second lens 22 also includes a second diffusing lens 22a. The focal length of the second condenser lens 23 changes when the second motor 102 moves the second diffusing lens 22a in the second optical axis direction.

[0029] According to the above configuration, when the beam irradiation position P on the powder layer 6 moves horizontally due to a change in the beam reflection angle in the scanning device 30, the second lens 22 moves in the second optical axis direction, and the focal length of the second condenser lens 23 changes. Therefore, even if the irradiation position P moves horizontally and the beam path length (dimension L in FIG. 3 ) from the irradiation device 4 to the irradiation position P changes, the beam remains condensed on the powder layer 6. Therefore, the thermal energy for melting can be concentrated on the powder layer 6.

[0030] The second focusing position changing device 20 according to the embodiment of the present disclosure may be a 3D scanner, and the second lens 22 may include a plurality of second diverging lenses 22 a. The second focusing position changing device 20 may further include an objective lens 25 fixed between the second lens 22 and the second focusing lens 23.

[0031] 2 and 4 , the 3D additive manufacturing evaluation system 5 includes a controller 90. The controller 90 includes a first focus control unit 91 for controlling the first focus position changing device 10. More specifically, the first focus control unit 91 is configured to control the first motor 101 so that the first diffusing lens 11a moves in the first optical axis direction in accordance with a change in the beam reflection angle by the scanning device 30.

[0032] More specifically, when the change in the reflection angle by the scanning device 30 increases the optical path length of the emitted light between the scanning device 30 and the irradiation position P (dimension L in FIG. 3), the first focusing control unit 91 controls the first motor 101 to move the first diffusing lens 11a in a direction away from the first condensing lens 13. Conversely, when the optical path length between the scanning device 30 and the irradiation position P decreases, the first focusing control unit 91 controls the first motor 101 to move the first diffusing lens 11a toward the first condensing lens 13.

[0033] According to a configuration in which the controller 90 includes the first focusing control unit 91, the first lens 11 of the first focusing position changing device 10 can be automatically moved in response to a change in the optical path length between the scanning device 30 and the irradiation position P. This makes it possible to automatically maintain the state in which the emitted light from the molten pool 8 is focused on the light receiving part of the optical measurement device 80, even if the optical path length between the irradiation position P and the optical measurement device 80 changes.

[0034] Furthermore, with the configuration in which the first focusing control unit 91 controls the first motor 101 as described above, even if the optical path length between the scanning device 30 and the irradiation position P increases, the distance between the first diffusing lens 11a and the first condenser lens 13 increases, and the focal length of the first condenser lens 13 increases. Even if the optical path length decreases, the distance between the first diffusing lens 11a and the first condenser lens 13 decreases, and the focal length of the first condenser lens 13 decreases. Therefore, even if the beam irradiation position P on the powder layer 6 moves horizontally, the light emitted from the molten pool 8 can be properly focused by the light receiving unit of the optical measurement device 80.

[0035] 4, the controller 90 further includes a second focus control unit 92 for controlling the second focus position changing device 20. More specifically, the second focus control unit 92 is configured to control the second motor 102 so that the second diffusing lens 22a moves in the second optical axis direction in response to a change in the beam reflection angle by the scanning device 30.

[0036] More specifically, when the beam path length (dimension L in FIG. 3 ) between the scanning device 30 and the irradiation position P increases due to a change in the reflection angle by the scanning device 30, the second condenser control unit 92 controls the second motor 102 to move the second diffusing lens 22 a in a direction away from the second condenser lens 23. Conversely, when the beam path length between the scanning device 30 and the irradiation position P decreases, the second condenser control unit 92 controls the second motor 102 to move the second diffusing lens 22 a toward the second condenser lens 23.

[0037] According to the configuration in which the controller 90 includes the second focus control unit 92, the second lens 22 of the second focus position changing device 20 can be automatically moved even if the beam path length (dimension L in FIG. 3 ) between the scanning device 30 and the irradiation position P changes. This makes it possible to automatically maintain the state in which the beam from the irradiation device 4 is focused on the powder layer 6.

[0038] Furthermore, with the configuration in which second focusing control unit 92 controls second motor 102 as described above, even if the beam path length between scanning device 30 and irradiation position P increases, the distance between second diffusing lens 22 a and second condensing lens 23 increases, and the focal length of second condensing lens 23 increases. Even if the beam path length decreases, the distance between second diffusing lens 22 a and second condensing lens 23 decreases, and the focal length of second condensing lens 23 decreases. Therefore, even if beam irradiation position P on powder layer 6 moves horizontally, the beam can be properly focused on powder layer 6.

[0039] The motor control of each of the first and second condensing control units 91 and 92 is synchronized with the control of the scanning device 30 to change the beam reflection angle. A specific implementation method is as follows. The second condensing control unit 92 is configured to monitor the beam reflection control by the scanning device 30. For example, data indicating the rotation amount and rotation direction of each of the X motor and Y motor is sent from a motor driver of the scanning device 30 to the second condensing control unit 92. The second condensing control unit 92 controls the second motor 102 in accordance with the data acquired from the motor driver. Furthermore, control data for the second motor 102 by the second condensing control unit 92 is sent to the first condensing control unit 91. The control data indicates the rotation amount and rotation direction of the second motor 102. The first condensing control unit 91 controls the first motor 101 in accordance with the control data acquired from the second condensing control unit 92. As a result, the first motor 101 and the second motor 102 are driven in synchronization with the control of the scanning device 30 to change the beam reflection angle.

[0040] 4 , the controller 90 further includes a measurement control unit 94 and an abnormality determination unit 95. The measurement control unit 94 is configured to send a command to the optical measurement device 80 to measure the intensity of the light emitted from the molten pool 8, and is also configured to acquire the measurement results from the optical measurement device 80. The measurement results acquired by the measurement control unit 94 are output to the abnormality determination unit 95.

[0041] The abnormality determination unit 95 is configured to determine that there is an abnormality in the molten pool 8 if the intensity of the light emitted by the optical measurement device 80 is not within an acceptable range. The acceptable range is defined by an upper threshold and a lower threshold. When the intensity of the light emitted falls below the lower threshold, it is caused by the temperature of the molten pool 8 being too low. When the intensity of the light emitted exceeds the upper threshold, it is caused by the temperature of the molten pool 8 being too high. Either of these events indicates that the quality of the molten pool 8 is insufficient. If it is determined that there is an abnormality in the molten pool 8, the additive manufacturing operation of the 3D additive manufacturing device 1 is interrupted, for example, by an operator's operation or by control by the controller 90. This allows appropriate measures to be taken on the 3D additive manufacturing device 1.

[0042] In this example, the tolerance range referenced by the abnormality determination unit 95 is the same regardless of the irradiation position P in the powder layer 6. Because the light emitted from the molten pool 8 is focused on the light receiving unit of the optical measurement device 80 regardless of the position of the molten pool 8, even if only a single tolerance range is referenced, the abnormality determination unit 95 can properly determine whether or not there is an abnormality in the molten pool 8. Therefore, the determination process of the abnormality determination unit 95 can be simplified compared to when multiple tolerance ranges are prepared depending on the position where the molten pool 8 is formed.

[0043] <3D Additive Manufacturing Evaluation Method> Figure 5 is a flowchart of a 3D Additive Manufacturing evaluation method according to an embodiment of the present disclosure. This evaluation method is a control process executed by the processor of the controller 90 each time a powder layer 6 is laid. Through execution of this evaluation method, the quality of the molten pool 8 is evaluated, and the powder layer 6 is transformed into a manufacturing layer 7. In the following description, "step" may be abbreviated as "S."

[0044] First, a beam irradiation step (S11) is performed in which a beam is irradiated onto the powder layer 6. The processor controls the irradiation device 4 and the scanning device 30, so that the beam is irradiated onto the powder layer 6, and a molten pool 8 is formed at the irradiation position P.

[0045] Next, a measurement step (S13) is executed to measure the intensity of the light emitted from the molten pool 8. The processor sends a measurement command to the analysis unit of the optical measurement device 80 and obtains the measurement result of the light emission intensity from the analysis unit. The processor that executes S13 is an example of the measurement control unit 94. Next, the processor determines whether the light emission intensity falls within an allowable range (S15). The processor that executes S15 is an example of the abnormality determination unit 95.

[0046] If it is determined that the measured intensity is within the allowable range (S15: YES), the processor controls the scanning device 30 to horizontally move the irradiation position P (S17). More specifically, the processor sends a predetermined command to the control driver of the scanning device 30, thereby horizontally moving the irradiation position P on the powder layer 6. The molten pool 8, which is no longer irradiated with the beam, gradually solidifies, and the forming layer 7 begins to be formed.

[0047] Next, the processor executes a second lens movement step (S19) of moving the second lens 22 (more specifically, the second diffusing lens 22a) of the second light-focusing position changing device 20 in the second optical axis direction in accordance with the irradiation position P, and a first lens movement step (S21) of moving the first lens 11 (more specifically, the first diffusing lens 11a) of the first light-focusing position changing device 10 in the first optical axis direction in accordance with the movement of the second lens 22. By executing S19 and S21, even if the irradiation position P moves in the horizontal direction, the beam is focused at the irradiation position P, and the light emitted from the molten pool 8 is focused by the light receiving unit of the optical measurement device 80. The processor executing S19 is an example of the second light-focusing control unit 92, and the processor executing S21 is an example of the first light-focusing control unit 91. Note that S19 and S21 may be executed simultaneously.

[0048] Next, the processor determines whether to continue the 3D additive manufacturing evaluation method (S23). If there are any remaining portions of the powder layer 6 that have not been irradiated with the laser, the processor determines to continue (S23: YES), and the process returns to S11. By repeating S11 to S23, the entire powder layer 6 is irradiated with the beam, and the modeling layer 7 is completed. If the processor determines to end the 3D additive manufacturing evaluation method (S23: NO), the control process ends. After the 3D additive manufacturing device 1 has further laid a new powder layer 6, the processor restarts the control process.

[0049] Furthermore, if it is determined that the intensity of the light emitted from the molten pool 8 is outside the acceptable range (S15: NO), the processor executes an abnormality notification step (S25) that displays information indicating an abnormality on a monitor (not shown) of the three-dimensional additive manufacturing device 1, etc., and terminates this three-dimensional additive manufacturing evaluation method.

[0050] <Others> The three-dimensional additive manufacturing evaluation system 5 does not need to include the second focusing position changing device 20. For example, if there is a device that raises and lowers at least one of the three-dimensional additive manufacturing evaluation system 5 or the base plate 9 in accordance with the irradiation position P, it is possible to focus the laser at the irradiation position P regardless of the irradiation position P. Alternatively, if the beam irradiated by the irradiation device 4 is laser light, an f-theta lens (Fθ lens) may be installed in the three-dimensional additive manufacturing evaluation system 5 instead of the second focusing position changing device 20. The Fθ lens is disposed between the scanning device 30 and the powder layer 6.

[0051] The controller 90 described above includes a processor and a memory (storage medium). The processor may be a CPU, a GPU, an MPU, a DSP, or a combination thereof. The processor according to other embodiments may be implemented by an integrated circuit such as a PLD, an ASIC, an FPGA, or an MCU. The memory is configured to temporarily or non-temporarily store various data and may be implemented by at least one of a RAM, a ROM, or a flash memory. The processor executes various control processes according to instructions from a program loaded into the memory. The controller 90 may be implemented by one or more arithmetic units, one or more control drivers, or a combination thereof.

[0052] <Summary> The contents described in the above-described embodiments can be understood, for example, as follows.

[0053] 1) A three-dimensional additive manufacturing evaluation system (5) according to at least one embodiment of the present disclosure comprises: an irradiation device (4) configured to irradiate a beam for melting a laid powder layer (6); a scanning device (30) for reflecting the beam from the irradiation device toward the powder layer and changing the reflection angle of the beam to move an irradiation position (P) of the beam on the powder layer; an optical measurement device (80) for measuring the intensity of light emitted from a molten pool formed at the irradiation position of the powder layer; a reflection device (40) arranged between the scanning device and the irradiation device and configured to reflect the light reflected by the scanning device toward the optical measurement device; and a first focusing position changing device (10) including a first lens (11) arranged between the reflection device and the optical measurement device and configured to move the first lens in a first optical axis direction that is the optical axis direction of the first lens.

[0054] According to the configuration 1), when the beam irradiation position on the powder layer moves horizontally, the first focusing position changing device can move the first lens in the first optical axis direction. That is, even if the optical path length between the irradiation position and the optical measurement device changes, the light emitted from the molten pool is maintained in a state where it is focused by the optical measurement device. This realizes a 3D additive manufacturing evaluation system that can accurately evaluate the quality of the molten pool.

[0055] 2) In some embodiments, the three-dimensional additive manufacturing evaluation system described in 1) above further includes a first focusing control unit (91) for controlling the first focusing position changing device so that the first lens moves in the first optical axis direction in response to a change in the reflection angle by the scanning device.

[0056] According to the configuration 2), the first lens can be automatically moved in response to changes in the optical path length between the scanning device and the irradiation position, so that the emitted light from the molten pool can be automatically kept focused on the optical measurement device even if the optical path length between the irradiation position and the optical measurement device changes.

[0057] 3) In some embodiments, the three-dimensional additive manufacturing evaluation system described in 2) above further includes a first focusing lens (13) fixed between the first focusing position changing device and the reflection device, wherein the first lens has a first diverging lens (11a), and the first focusing control unit is configured to control the first focusing position changing device so that the first diverging lens moves in a direction away from the first focusing lens when the beam path length between the scanning device and the irradiation position increases due to the change in the reflection angle by the scanning device.

[0058] According to the configuration 3), even if the optical path length from the molten pool to the optical measurement device increases as the beam path length between the scanning device and the irradiation position increases, the distance between the first diverging lens and the first condenser lens increases, and the focal length of the first condenser lens also increases. Therefore, even if the beam irradiation position changes in the horizontal direction, the light emitted from the molten pool can be properly condensed by the optical measurement device.

[0059] 4) In some embodiments, the three-dimensional additive manufacturing evaluation system described in any one of 1) to 3) above further includes an abnormality determination unit (95) for determining that there is an abnormality in the molten pool when the intensity of the light emission measured by the optical measurement device is not within an acceptable range.

[0060] According to the configuration 4) above, if the abnormality determination unit determines that there is an abnormality in the molten area, measures such as interrupting additive manufacturing can be taken by operation by an operator or by processor control.

[0061] 5) In some embodiments, in the three-dimensional additive manufacturing evaluation system described in 4) above, the tolerance range referenced by the abnormality determination unit is the same regardless of the irradiation position in the powder layer.

[0062] According to the configuration of 5) above, the light emitted from the molten pool is collected by the optical measurement device regardless of the position of the molten pool, so even if only a single tolerance range is referenced, the abnormality determination unit can properly determine whether or not there is an abnormality in the molten pool. Therefore, the determination process of the abnormality determination unit can be simplified compared to when multiple tolerance ranges are prepared depending on the position where the molten pool is formed.

[0063] 6) In some embodiments, the three-dimensional additive manufacturing evaluation system described in any one of 1) to 5) above further includes a second focusing position changing device (20) that includes a second lens (22) arranged between the reflecting device and the irradiating device and is configured to move the second lens in a second optical axis direction that is the optical axis direction of the second lens.

[0064] According to the configuration of 6), when the beam irradiation position on the powder layer moves horizontally, the second lens moves in the second optical axis direction. Even if the beam path length from the irradiation device to the irradiation position changes, the beam remains focused on the powder layer. Therefore, the thermal energy for melting can be concentrated on the powder layer.

[0065] 7) In some embodiments, the three-dimensional additive manufacturing evaluation system described in 6) above further includes a second focusing control unit (92) for controlling the second focusing position changing device so that the second lens moves in the second optical axis direction in response to a change in the reflection angle by the scanning device.

[0066] According to the above configuration 7), even if the beam path length between the reflecting device and the irradiation position changes, the state in which the beam is focused on the powder layer can be automatically maintained.

[0067] 8) In some embodiments, the three-dimensional additive manufacturing evaluation system described in 7) above further includes a second focusing lens (23) arranged between the second focusing position changing device and the reflection device, wherein the second lens has a second diverging lens (22a), and the second focusing control unit is configured to control the second focusing position changing device so that the second diverging lens moves in a direction away from the second focusing lens when the change in the reflection angle by the scanning device increases the beam path length between the scanning device and the irradiation position.

[0068] According to the configuration of 8), even if the beam path length between the scanning device and the irradiation position increases, the distance between the second diverging lens and the second condensing lens is increased, and the second focal length of the second condensing lens is also increased, so that the beam can be properly focused on the powder layer even if the beam irradiation position changes in the horizontal direction.

[0069] 9) A three-dimensional additive manufacturing evaluation method according to at least one embodiment of the present disclosure includes: a measurement step (S13) of measuring, using an optical measurement device (80), the intensity of light emitted from a molten pool (8) formed at a beam irradiation position (P) on a powder layer (6); and a first lens movement step (S21) of moving, during the measurement step, a first lens (11) disposed between a reflection device (40) that reflects the light emitted toward the optical measurement device and the optical measurement device, in a first optical axis direction that is the optical axis direction of the first lens, according to the irradiation position on the powder layer.

[0070] The configuration 9) above provides the same technical advantages as the configuration 1).

[0071] DESCRIPTION OF SYMBOLS 1: 3D additive manufacturing device 3: Powder supply device 4: Irradiation device 5: 3D additive manufacturing evaluation system 6: Powder layer 7: Manufacturing layer 8: Molten pool 9: Base plate 10: First focusing position changing device 11: First lens 11a: First diffusing lens 13: First condensing lens 15: Objective lens 20: Second focusing position changing device 22: Second lens 22a: Second diffusing lens 23: Second condensing lens 25: Objective lens 30: Scanning device 40: Reflection device 80: Optical measurement device 90: Controller 91: First focusing control unit 92: Second focusing control unit 94: Measurement control unit 95: Abnormality determination unit 101: First motor 102: Second motor H, L: Arrow P : Irradiation position Q, S: Arrow

Claims

1. A three-dimensional additive manufacturing evaluation system comprising: an irradiation device configured to irradiate a beam for melting a laid powder layer; a scanning device for reflecting the beam from the irradiation device toward the powder layer and changing the reflection angle of the beam to move the irradiation position of the beam on the powder layer; an optical measurement device for measuring the intensity of light emission from a molten pool formed at the irradiation position of the powder layer; a reflection device arranged between the scanning device and the irradiation device and configured to reflect the light emission reflected by the scanning device toward the optical measurement device; and a first focusing position changing device including a first lens arranged between the reflection device and the optical measurement device and configured to move the first lens in a first optical axis direction that is the optical axis direction of the first lens.

2. The three-dimensional additive manufacturing evaluation system of claim 1, further comprising a first focusing control unit for controlling the first focusing position changing device so that the first lens moves in the first optical axis direction in response to a change in the reflection angle by the scanning device.

3. The three-dimensional additive manufacturing evaluation system of claim 2, further comprising a first focusing lens fixed between the first focusing position changing device and the reflection device, the first lens having a first diffusing lens, and the first focusing control unit configured to control the first focusing position changing device so that the first diffusing lens moves in a direction away from the first focusing lens when the beam path length between the scanning device and the irradiation position increases due to the change in the reflection angle by the scanning device.

4. A three-dimensional additive manufacturing evaluation system as described in any one of claims 1 to 3, further comprising an abnormality judgment unit for determining that there is an abnormality in the molten pool if the intensity of the light emission measured by the optical measuring device is not within an acceptable range.

5. The three-dimensional additive manufacturing evaluation system according to claim 4, wherein the tolerance range referenced by the abnormality determination unit is the same regardless of the irradiation position in the powder layer.

6. The three-dimensional additive manufacturing evaluation system according to claim 1 or 2, further comprising a second focusing position changing device including a second lens arranged between the reflecting device and the irradiating device and configured to move the second lens in a second optical axis direction which is the optical axis direction of the second lens.

7. The three-dimensional additive manufacturing evaluation system of claim 6, further comprising a second focusing control unit for controlling the second focusing position changing device so that the second lens moves in the second optical axis direction in response to a change in the reflection angle by the scanning device.

8. The three-dimensional additive manufacturing evaluation system of claim 7, further comprising a second focusing lens arranged between the second focusing position changing device and the reflection device, the second lens having a second diffusing lens, and the second focusing control unit configured to control the second focusing position changing device so that the second diffusing lens moves in a direction away from the second focusing lens when the change in the reflection angle by the scanning device increases the beam path length between the scanning device and the irradiation position.

9. A three-dimensional additive manufacturing evaluation method comprising: a measurement step of measuring the intensity of light emitted from a molten pool formed at a position irradiated by the beam on a powder layer using an optical measurement device; and a first lens movement step of moving a first lens, which is disposed between a reflecting device that reflects the light emitted toward the optical measurement device and the optical measurement device, in a first optical axis direction that is the optical axis direction of the first lens according to the irradiation position on the powder layer during execution of the measurement step.

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