Three dimensional laminating and shaping apparatus and control method for three dimensional laminating and shaping apparatus

Abstract

To provide a three dimensional lamination shaping apparatus and a control method of the three dimensional lamination shaping apparatus, capable of improving throughput required for shaping processing.SOLUTION: A three dimensional additive manufacturing device 1 includes a shaping plate 22, a powder supply device 16, a beam irradiation device 2, a plurality of detection parts 46, and a control part. The control unit controls the irradiation device 2. In addition, when acquiring electrons, the control unit controls the irradiation device 2 so that only a predetermined irradiation range in the powder layer is irradiated with the primary beam.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a three-dimensional additive manufacturing device that builds a structure by stacking thin layers of powder material on a stage one by one, and a method for controlling the three-dimensional additive manufacturing device. [Background technology]

[0002] In recent years, 3D additive manufacturing technology, which creates objects by stacking thin layers of powder material one by one, has been attracting attention, and many types of 3D additive manufacturing technology have been developed, depending on the powder material and manufacturing method.

[0003] In a conventional 3D additive manufacturing device, for example, powder material is spread layer by layer on a base plate installed on the upper surface of a stage. Next, only the two-dimensional structure portion of the powder material spread on the base plate, which corresponds to one cross section of the object, is melted using a heating mechanism consisting of an electron beam or laser. Then, the layer of powder material is stacked one by one in the height direction (Z direction) to form the object (see, for example, Patent Document 1).

[0004] Patent document 1 also describes a technology in which a detection unit is provided to detect reflected electrons generated when an electron beam is irradiated onto a powder material, and the state of the object is determined based on the information detected by this detection unit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-42410 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the technology described in Patent Document 1, in order to acquire backscattered electrons, the entire meltable area in all layers of the modeling process is irradiated with a primary ray, which is an electron beam. Therefore, the technology described in Patent Document 1 requires the primary ray to be scanned over the entire meltable area. As a result, it takes a long time to acquire a backscattered electron image, which causes a problem of a decrease in throughput in the modeling process.

[0007] In consideration of the above problems, an object of the present invention is to provide a three-dimensional additive manufacturing apparatus and a control method for a three-dimensional additive manufacturing apparatus that can improve the throughput of the manufacturing process. [Means for solving the problem]

[0008] In order to solve the above problems and achieve the object of the present invention, the 3D additive manufacturing apparatus of the present invention is a 3D additive manufacturing apparatus that manufactures a model. The 3D additive manufacturing apparatus includes a modeling plate, a powder supplying device, an irradiation device, a detection unit, and a control unit. The powder supplying device supplies powder material to the modeling plate to form a powder layer. The irradiation device irradiates the powder layer with a primary beam. The detection unit detects electrons generated when the primary beam irradiates the powder material. The control unit controls the irradiation device. Furthermore, when acquiring electrons, the control unit controls the irradiation device so that the primary beam is irradiated only onto a predetermined irradiation range in the powder layer.

[0009] A control method for a three-dimensional additive manufacturing apparatus according to the present invention is a control method used for the three-dimensional additive manufacturing apparatus having the above-described configuration, and the control unit controls the irradiation device so that the primary beam is irradiated only onto a predetermined irradiation range in the powder layer when acquiring electrons. [Effects of the Invention]

[0010] According to the three-dimensional additive manufacturing device and the control method for the three-dimensional additive manufacturing device of the present invention, it is possible to improve the throughput of the manufacturing process. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view showing a three-dimensional additive manufacturing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing an example of the configuration of a control system of a three-dimensional additive manufacturing apparatus according to an embodiment of the present invention. [Figure 3] 3 is a flowchart showing the operation procedure of the three-dimensional additive manufacturing device according to the embodiment of the present invention. [Figure 4] 1 is a diagram showing an example of modeling data of a model formed by a three-dimensional additive manufacturing apparatus according to an embodiment of the present invention. FIG. [Figure 5] 10 is an image showing an example of an irradiation range in a backscattered electron image acquisition process of a three-dimensional additive manufacturing apparatus according to an embodiment of the present invention. [Figure 6] 10 is an image showing an enlarged view of the irradiation range. [Figure 7] 10 is an image showing an enlarged view of the irradiation range. [Figure 8] 10 is an image showing another example of the irradiation range in the backscattered electron image acquisition process of the three-dimensional additive manufacturing apparatus according to the embodiment of the present invention. [Figure 9] 10 is an image showing another example of the irradiation range in the backscattered electron image acquisition process of the three-dimensional additive manufacturing apparatus according to the embodiment of the present invention. [Figure 10] 10 is an image showing another example of the irradiation range in the backscattered electron image acquisition process of the three-dimensional additive manufacturing apparatus according to the embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing another example of modeling data of a model formed by the three-dimensional additive manufacturing apparatus according to the embodiment of the present invention. [Figure 12] 10 is an image showing another example of the irradiation range in the backscattered electron image acquisition process of the three-dimensional additive manufacturing apparatus according to the embodiment of the present invention. [Figure 13] FIG. 10 is a diagram showing another example of modeling data of a model formed by the three-dimensional additive manufacturing apparatus according to the embodiment of the present invention. [Figure 14] FIG. 10 is a diagram showing another example of modeling data of a model formed by the three-dimensional additive manufacturing apparatus according to the embodiment of the present invention. [Figure 15] 10 is an image showing another example of the irradiation range in the backscattered electron image acquisition process of the three-dimensional additive manufacturing apparatus according to the embodiment of the present invention. [Figure 16] 10 is an image showing another example of the irradiation range in the backscattered electron image acquisition process of the three-dimensional additive manufacturing apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] 1. Example of implementation 1-1.Configuration of 3D additive manufacturing equipment First, a three-dimensional additive manufacturing device according to an embodiment of the present invention (hereinafter referred to as "this example") will be described with reference to FIG. Fig. 1 is a schematic cross-sectional view showing a three-dimensional additive manufacturing apparatus according to this embodiment. In the following description, in order to clarify the shapes and positional relationships of the various components of the three-dimensional additive manufacturing apparatus, the left-right direction in Fig. 1 is referred to as the X direction, the depth direction in Fig. 1 as the Y direction, and the up-down direction in Fig. 1 as the Z direction. The X direction, Y direction, and Z direction are perpendicular to each other. Furthermore, the X direction and Y direction are parallel to the horizontal direction, and the Z direction is parallel to the vertical direction.

[0013] The 3D additive manufacturing device 1 shown in Figure 1 is a device that irradiates powder material made of metal powder such as titanium, aluminum, iron, etc. with an electron beam to melt the powder material, and then stacks layers of this solidified powder material to form a three-dimensional object.

[0014] 1, the 3D additive manufacturing apparatus 1 includes a vacuum chamber 3, a beam irradiation device 2, a powder supplying device 16, a modeling table 18, a modeling box 20, and a collection box 21. The 3D additive manufacturing apparatus 1 also includes a modeling plate 22, an inner base 24, a plate moving device 26, a radiation shield cover 28, a mask cover 30, a camera 42, and a shutter 44. The 3D additive manufacturing apparatus 1 also includes a plurality of detection units 46 that detect reflected electrons, which are an example of electrons.

[0015] The vacuum chamber 3 is a chamber for creating a vacuum state by evacuating the air inside the chamber with a vacuum pump (not shown).

[0016] The beam irradiation device 2 is a device that irradiates an electron beam 15 onto a build surface 32a of a powder layer formed from a build plate 22 or a powder material 32. The build surface 32a corresponds to the upper surface of the powder layer. The state of the powder layer changes as the 3D additive manufacturing process progresses. Although not shown, the beam irradiation device 2 has an electron gun that generates the electron beam 15, a focusing lens that focuses the electron beam generated by the electron gun, and a deflection lens that deflects the electron beam 15 focused by the focusing lens. The focusing lens is configured using a focusing coil and focuses the electron beam 15 by the magnetic field generated by the focusing coil. The deflection lens is configured using a deflection coil and deflects the electron beam 15 by the magnetic field generated by the deflection coil.

[0017] The powder supplying device 16 is a device that supplies powder material 32, which is an example of a powder material that serves as a raw material for the molded object 38, onto the molding plate 22 to form a powder layer. The powder supplying device 16 has a hopper 16a, a powder dropper 16b, and a squeegee 16c. The hopper 16a is a container for storing metal powder. The powder dropper 16b is a device that drops the powder material 32 stored in the hopper 16a onto the molding table 18. The squeegee 16c is an elongated member that is long in the Y direction and has a blade 16d for spreading the powder. The squeegee 16c spreads the powder material 32 dropped by the powder dropper 16b over the molding table 18. The squeegee 16c is movable in the X direction to spread the powder material 32 over the entire surface of the molding table 18.

[0018] The modeling table 18 is arranged horizontally inside the vacuum chamber 3. The modeling table 18 is arranged below the powder supply device 16. The center of the modeling table 18 is open. The shape of the opening of the modeling table 18 is circular in plan view or angular in plan view (for example, rectangular in plan view).

[0019] The modeling box 20 is a box that forms a space for modeling. The upper end of the modeling box 20 is connected to the edge of the opening of the modeling table 18. The lower end of the modeling box 20 is connected to the bottom wall of the vacuum chamber 3.

[0020] The recovery box 21 is a box for recovering the powder material 32 that has been supplied onto the modeling table 18 by the powder supplying device 16 in excess of what is needed.

[0021] The shaping plate 22 is a plate for forming a shaped object 38 using the powder material 32. The shaped object 38 is formed by stacking on the shaping plate 22. The shaping plate 22 is formed to be circular or angular in plan view to match the shape of the opening of the shaping table 18. The shaping plate 22 is connected (grounded) to the inner base 24 by an earth wire 34 to prevent it from being electrically floating. The inner base 24 is maintained at GND (ground) potential. The powder material 32 is spread over the shaping plate 22 and the inner base 24.

[0022] The inner base 24 is provided so as to be movable in the vertical direction (Z direction). The shaping plate 22 moves vertically together with the inner base 24. The inner base 24 has larger outer dimensions than the shaping plate 22. The inner base 24 slides vertically along the inner surface of the shaping box 20. A sealing member 36 is attached to the outer periphery of the inner base 24. The sealing member 36 is a member that maintains slidability and airtightness between the outer periphery of the inner base 24 and the inner surface of the shaping box 20. The sealing member 36 is made of a heat-resistant and elastic material.

[0023] The plate moving device 26 is a device that moves the shaping plate 22 and the inner base 24 in the up-down direction. The plate moving device 26 includes a shaft 26a and a drive mechanism unit 26b. The shaft 26a is connected to the underside of the inner base 24. The drive mechanism unit 26b includes a motor and a power transmission mechanism (not shown), and moves the shaping plate 22 and the inner base 24 together with the shaft 26a in the up-down direction by driving the power transmission mechanism using the motor as a drive source. The power transmission mechanism is configured, for example, by a rack-and-pinion mechanism, a ball-screw mechanism, or the like.

[0024] The radiation shield cover 28 is disposed between the build plate 22 and the beam irradiation device 2 in the Z direction. The radiation shield cover 28 is made of a metal such as stainless steel. The radiation shield cover 28 shields against radiant heat generated when the electron beam 15 is irradiated onto the powder material 32 by the beam irradiation device 2. When the electron beam 15 is irradiated onto the powder material 32 for sintering, the powder material 32 melts. However, if the heat radiated from the build surface 32a of the powder layer at this time, i.e., the radiant heat, is widely dispersed within the vacuum chamber 3, thermal efficiency deteriorates. In contrast, when the radiation shield cover 28 is disposed above the build plate 22, the heat radiated from the build surface 32a is shielded by the radiation shield cover 28, and the shielded heat is reflected by the radiation shield cover 28 and returned to the build plate 22. This allows for efficient use of the heat generated by the irradiation of the electron beam 15.

[0025] The radiation shield cover 28 also functions to prevent evaporated material generated when the powder material 32 is irradiated with the electron beam 15 from adhering (depositing) onto the inner wall of the vacuum chamber 3. When the powder material 32 is irradiated with the electron beam 15, part of the molten metal turns into mist-like evaporated material and rises from the building surface 32a. The radiation shield cover 28 is arranged to cover the space above the building surface 32a to prevent this evaporated material from diffusing inside the vacuum chamber 3.

[0026] The mask cover 30 has an opening 30a and a mask portion 30b. When forming the molded object 38, the mask cover 30 is placed over the top surface of the powder material 32, i.e., the molded surface 32a. The opening 30a exposes the powder material 32 spread on the molded object 38, while the mask portion 30b shields the powder material 32 located outside the opening 30a. The shape of the opening 30a is set to match the shape of the molded object 22. For example, if the molded object 22 is circular in plan view, the opening 30a is set to be circular in plan view accordingly, and if the molded object 22 is rectangular in plan view, the opening 30a is set to be rectangular in plan view accordingly.

[0027] The mask cover 30 is disposed below the radiation shield cover 28. The opening 30a and mask portion 30b of the mask cover 30 are disposed between the build plate 22 and the radiation shield cover 28 in the Z direction. The mask cover 30 has an enclosure portion 30c. The enclosure portion 30c is disposed so as to enclose the space above the opening 30a. A portion (upper portion) of the enclosure portion 30c overlaps with the radiation shield cover 28 in the Z direction. The enclosure portion 30c functions to shield radiant heat generated from the build surface 32a and to suppress the diffusion of evaporated materials generated from the build surface 32a. In other words, the enclosure portion 30c functions similarly to the radiation shield cover 28.

[0028] The mask cover 30 is made of a metal with a higher melting point than the powder material 32 used as the raw material for the molded object 38. The mask cover 30 is also made of a material that is less reactive with the powder material 32. Titanium, for example, can be used as a material for the mask cover 30. The mask cover 30 may also be made of the same metal as the powder material 32 used. The mask cover 30 is electrically grounded to GND. The mask cover 30 serves as an electrical shield when the powder material 32 is pre-sintered by irradiating it with an electron beam 15 in a pre-heating step prior to the main sintering step, which will be described later, thereby minimizing powder scattering.

[0029] The camera 42 is a camera capable of capturing an image of the powder layer's building surface 32a. The camera 42 is positioned offset in the Y direction from the beam irradiation device 2 so as not to interfere with the position of the beam irradiation device 2. The camera 42 is preferably configured as a visible light camera such as a digital video camera. The camera 42 captures an image of the powder layer's building surface 32a to generate an image (image data) of the powder layer. Therefore, the image generated by the camera 42 is an image that shows the state of the powder layer's building surface 32a. The image is captured by the camera 42 with illumination light emitted by an illumination light source (not shown) included in the 3D additive manufacturing device 1 irradiating the powder layer's building surface 32a.

[0030] The shutter 44 protects the camera 42 and the observation window so that evaporated substances generated from the manufacturing surface 32a do not adhere to the camera 42 or the observation window when the powder material 32 is melted by irradiation with the electron beam 15. The camera 42 photographs the manufacturing surface 32a with the shutter 44 open. Furthermore, in processes in which evaporated substances are likely to be generated or in which a large amount of evaporated substances are generated, i.e., when the powder material 32 is melted by the electron beam 15, the shutter 44 is closed.

[0031] A plurality of detectors 46 for detecting reflected electrons are disposed below the beam irradiation device 2. Specifically, the detection unit 46 is disposed between the beam irradiation device 2 and the printing surface 32a of the object 38 to be formed on the printing plate 22. The position at which the detection unit 46 is provided is not limited to the example shown in Fig. 1, and the detection unit 46 may be disposed at various other positions.

[0032] 1-2. Control system of 3D additive manufacturing equipment Next, the configuration of the control system of the three-dimensional additive manufacturing apparatus 1 will be described with reference to FIG. FIG. 2 is a block diagram showing an example of the configuration of a control system of the three-dimensional additive manufacturing apparatus 1 of this embodiment. As shown in Figure 2, the 3D additive manufacturing device 1 has a polarization amplifier control circuit 101 which is an electron beam control unit, an analog-to-digital conversion circuit (ADC) 102, a preamplifier (Pre-AMP) 103, a personal computer (PC) 104 which is an example of a control unit, and a memory unit 105.

[0033] The polarization amplifier control circuit 101 is connected to the beam irradiation device 2 and a PC 104. The PC 104 transmits a control signal to the polarization amplifier control circuit 101 based on beam scanning information stored in a storage unit 105. The polarization amplifier control circuit 101 controls the beam irradiation device 2 based on the control signal. As a result, the beam irradiation device 2 irradiates the electron beam 15 at a predetermined position. The polarization amplifier control circuit 101 also transmits beam irradiation position information indicating the irradiation position of the electron beam 15 to the PC 104.

[0034] The Pre-AMP 103 is connected to the detection unit 46 and the ADC 102. The Pre-AMP 103 converts the reflected electron current detected by the detection unit 46 from a current signal to a voltage signal. The voltage signal converted by the Pre-AMP 103 is transmitted to the ADC 102. The ADC 102 converts the reflected electron signal, which has become a voltage signal, from an analog signal to a digital signal and transmits it to the PC 104.

[0035] The PC 104 also has an image processing unit (not shown). The image processing unit of the PC 104 captures images generated by the camera 42 and performs predetermined image processing on the captured images. The PC 104 then outputs the camera images that have been subjected to image processing by the image processing unit to a display unit (not shown).

[0036] The storage unit 105 stores modeling data 200 (see FIG. 4 ). Then, the PC 104 creates beam scanning information based on the modeling data 200 and stores the created beam scanning information in the storage unit 105. Note that, although an example in which the beam scanning information is created by the PC 104 has been described, the present invention is not limited to this, and a user may create the beam scanning information based on the modeling data 200 and store the information in the storage unit 105.

[0037] 1-3. Example of operation of 3D additive manufacturing equipment Next, an example of the operation of the three-dimensional additive manufacturing apparatus 1 having the above-described configuration will be described with reference to FIG.

[0038] FIG. 3 is a flowchart showing an example of the operation of the three-dimensional additive manufacturing device 1.

[0039] 3, the polarization amplifier control circuit 101 controls the beam irradiation device 2 based on a control signal from the PC 104. As a result, the beam irradiation device 2 operates based on a control command given by the polarization amplifier control circuit 101 to heat the shaping plate 22 (step S1). In step S1, the beam irradiation device 2 operates under the control of the polarization amplifier control circuit 101 to irradiate the shaping plate 22 with the electron beam 15 through the opening 30a of the mask cover 30. At this time, the polarization amplifier control circuit 101 defocuses the electron beam 15 using an objective lens or the like provided in the beam irradiation device 2. This defocusing results in a state in which the focal position of the electron beam 15 is shifted downward from the upper surface of the shaping plate 22, i.e., an underfocus state.

[0040] The polarization amplifier control circuit 101 also controls the beam irradiation device 2 to scan the electron beam 15 over an area wider than the opening 30a of the mask cover 30. As a result, the shaping plate 22 is heated by the irradiation of the electron beam 15. The shaping plate 22 is heated to a temperature sufficient for pre-sintering the powder material 32. Once the shaping plate 22 has been heated to a predetermined temperature, the beam irradiation device 2 stops irradiating the electron beam 15. Scanning the electron beam 15 over an area wider than the opening 30a of the mask cover 30 means scanning the electron beam 15 over an area wider than the opening area of ​​the opening 30a so that the opening 30a fits within the scanning range (scanning area) of the electron beam 15. The scanning range (scanning area) of the electron beam 15 in the beam irradiation device 2 may be narrower than the opening 30a of the mask cover 30.

[0041] Next, the shaping plate 22 is lowered by a predetermined amount (step S2). In step S2, the plate moving device 26 lowers the inner base 24 by a predetermined amount so that the upper surface of the shaping plate 22 is slightly lower than the upper surface of the powder material 32 spread on the shaping table 18. At this time, the shaping plate 22 is lowered by the predetermined amount together with the inner base 24. The predetermined amount (hereinafter also referred to as "ΔZ") described here corresponds to the thickness of one layer when the shaped object 38 is shaped by stacking.

[0042] Next, the mask cover 30 is raised (step S3). In step S3, for example, the squeegee 16c is moved in the X direction to bring a cam follower (not shown) into contact with the inclined surface of a lifting member provided on the mask cover 30. As a result, the mask cover 30 is raised along the Z direction.

[0043] Next, the powder material 32 is spread all over the modeling plate 22 (step S4). In step S4, the powder supplying device 16 drops the powder material 32, which has been supplied from the hopper 16a to the powder dropper 16b, onto the modeling table 18 using the powder dropper 16b. Then, the powder supplying device 16 moves the squeegee 16c from one end to the other end in the X direction. This causes the powder material 32 to be spread all over the inner base 24. At this time, the powder material 32 is spread all over the modeling table 18 to a thickness equivalent to ΔZ. In addition, excess powder material 32 is collected in the collection box 21.

[0044] Next, the mask cover 30 is lowered (step S5). In step S5, the squeegee 16c is moved to a position where the cam follower of the squeegee 16c does not contact the lifting member. As a result, the mask cover 30 is lowered to the upper surface of the shaping plate 22. At this time, the powder material 32 spread on the shaping plate 22 is exposed to the outside through the opening 30a of the mask cover 30. In addition, the powder material 32 present around the shaping plate 22 is covered by the mask portion 30b of the mask cover 30.

[0045] Next, the powder material 32 is pre-sintered (step S6). In step S6, the polarization amplifier control circuit 101 controls the beam irradiation device 2 based on a control signal from the PC 104. As a result, the electron beam 15 is irradiated onto the powder material 32 on the build plate 22 through the opening 30a of the mask cover 30. At this time, the polarization amplifier control circuit 101 defocuses the electron beam 15 using an objective lens or the like provided in the beam irradiation device 2. This defocusing causes the focal position of the electron beam 15 to be shifted downward below the upper surface (build surface 32a) of the powder material 32, i.e., an underfocus state. In addition, the polarization amplifier control circuit 101 controls the beam irradiation device 2 to scan the electron beam 15 over a wider area than the opening 30a of the mask cover 30. As a result, not only the powder material 32 exposed in the opening 30a but also the powder material 32 located outside the opening 30a (powder material 32 shielded by the mask portion 30b) are pre-sintered.

[0046] Thus, the process of covering the powder material 32 spread on the building plate 22 with a mask cover 30 having openings 30a and irradiating the powder material 32 with an electron beam 15 through the openings 30a to pre-sinter the powder material 32 corresponds to the first process. In this first process, the electron beam 15 is scanned over an area wider than the openings 30a of the mask cover 30, thereby pre-sintering at least all of the powder material 32 exposed to the openings 30a. Furthermore, pre-sintering the powder material 32 can impart conductivity to the powder material 32. This can suppress powder scattering during the sintering process that follows the pre-heating process.

[0047] Next, the powder material 32 is melted and solidified (step S7). In step S7, the powder material 32 that has been pre-sintered as described above is irradiated with the electron beam 15 to melt and solidify, thereby finally sintering the powder material 32 as a pre-sintered body. This step corresponds to the second step. In the second step, the beam irradiation device 2 selectively melts the powder material 32 on the building plate 22 by scanning with the electron beam 15 based on the building data 200 of the target object 38, i.e., two-dimensional data obtained by slicing three-dimensional CAD (Computer-Aided Design) data to a certain thickness. The powder material 32 melted by irradiation with the electron beam 15 solidifies after the electron beam has passed. This completes the building of the first layer. Note that the second step corresponds to a selective melting step, since the powder material 32 spread on the building plate 22 is selectively melted and solidified by scanning with the electron beam 15.

[0048] Next, the mask cover 30 is raised (step S8). Next, a backscattered electron image is acquired (step S9). In step S9, first, the polarization amplifier control circuit 101 controls the beam irradiation device 2 based on a control signal from the PC 104. As a result, the beam irradiation device 2 operates based on a control command given from the polarization amplifier control circuit 101, and scans the electron beam 15 over the pre-sintering region 39 where the pre-sintered powder material 32 exists and the model 38. At this time, the beam irradiation device 2 minimizes the electron beam current of the electron beam 15 and focuses the electron beam 15 on the modeling surface 32a. Then, the detection unit 46 detects the backscattered electrons generated by the electron beam 15.

[0049] The detector 46 outputs the detected backscattered electron signal to the PC 104 via the Pre-AMP 103. The image processor of the PC 104 then performs arithmetic processing on the backscattered electron signal (backscattered electron information) acquired from the detector 46 to acquire a backscattered electron image (BSE image). The image processor also stores the acquired BSE image in the memory 105.

[0050] Before performing the processing of step S9, the PC 104 sets the irradiation range of the electron beam 15 based on the modeling data 200 stored in the storage unit 105. Then, in the processing of step S9, the PC 104 outputs a control signal to the polarization amplifier control circuit 101 based on the set irradiation range. As a result, the polarization amplifier control circuit 101 controls the beam irradiation device 2 so that the electron beam 15 is irradiated onto the predetermined irradiation range.

[0051] An example of the irradiation range of the electron beam 15 executed in the processing of step S9 and step S17 to be described later will be described later.

[0052] Next, the mask cover 30 is lowered (step S10), and the build surface 32a is heated in preparation for spreading the powder material 32 (step S11). In step S11, the polarization amplifier control circuit 101 controls the beam irradiation device 2 based on a control signal from the PC 104. As a result, the beam irradiation device 2 operates based on a control command given by the polarization amplifier control circuit 101, and irradiates the build surface 32a with the electron beam 15 through the opening 30a of the mask cover 30. At this time, the polarization amplifier control circuit 101 defocuses the electron beam 15 using an objective lens or the like provided in the beam irradiation device 2. This defocusing results in a state in which the focal position of the electron beam 15 is shifted downward from the build surface 32a, i.e., an underfocus state.

[0053] The polarization amplifier control circuit 101 also controls the beam irradiation device 2 to scan the electron beam 15 over an area wider than the opening 30a of the mask cover 30. As a result, the electron beam 15 is irradiated onto the entire surface 32a to be molded that is exposed through the opening 30a. The surface 32a to be molded is heated to a temperature sufficient to temporarily sinter the powder material 32. Once the surface 32a to be molded has been heated to a predetermined temperature, the beam irradiation device 2 stops irradiating the electron beam 15.

[0054] Next, the shaping plate 22 is lowered by a predetermined amount (ΔZ) (step S12). In step S12, the plate moving device 26 lowers the inner base 24 by ΔZ so that the shaping surface 32a is slightly lower than the upper surface of the powder material 32 spread on the shaping table 18.

[0055] Next, the mask cover 30 is raised (step S13), and the powder material 32 is spread over the building plate 22 (step S14). In step S14, the powder supplying device 16 operates in the same manner as in step S4 above.

[0056] Next, the mask cover 30 is lowered (step S15), and the powder material 32 is pre-sintered (step S16). This step corresponds to step 1. In step S16, the beam irradiation device 2 operates in the same manner as in step S6.

[0057] When the preliminary sintering process of the powder material 32 is completed in the process of step S16, a backscattered electron image is acquired (step S17). In the process of step S17, similar to the process of step S9, the polarization amplifier control circuit 101 controls the beam irradiation device 2 and acquires a backscattered electron image (BSE image) by the detection unit 46. In the process of step S17, a backscattered electron image of the preliminary sintered body is acquired. Note that before the process of step S17, a process of raising the mask cover 30 is performed, and after the process of step S17, a process of lowering the mask cover 30 is performed.

[0058] Next, the powder material 32 is melted and solidified (step S18). This step corresponds to the second step. In step S18, the beam irradiation device 2 operates in the same manner as in step S7 above. This completes the formation of the second layer.

[0059] Thereafter, the processes of steps S8 to S18 are repeated until the formation of the object 38 is completed in step S19. The formation of the object 38 is completed when the powder material 32 has been melted and solidified for the number of layers required to form the object 38. In this way, the desired object 38 is obtained.

[0060] In the above-described example of operation, the operation of acquiring a BSE image is performed after the main sintering step in step S7 and after the processing in step S11, but the timing of performing the operation of acquiring a BSE image is not limited to this. For example, the operation of acquiring a BSE image may be performed after the preliminary sintering step in step S6.

[0061] 2. Irradiation range when acquiring backscattered electron images Next, the irradiation range of the electron beam 15 when acquiring a backscattered electron image (BSE image) in the processes of steps S9 and S17 described above will be described with reference to FIGS.

[0062] FIG. 4 is a diagram showing an example of modeling data 200 of a model 38 modeled by the above-described three-dimensional additive manufacturing apparatus 1. 4 is stored in advance in the storage unit 105. Then, the PC 104 outputs a control signal to the polarization amplifier control circuit 101 based on the modeling data 200. The polarization amplifier control circuit 101 controls the beam irradiation device 2 based on the control signal from the PC 104, and irradiates the powder material 32 with the electron beam 15.

[0063] Furthermore, before outputting a control signal to the polarization amplifier control circuit 101, the PC 104 recognizes the size of the vicinity of the object 38, the shape and coordinates of the object 38, etc. (hereinafter referred to as object information) from the object forming data 200. Then, based on the recognized object information, the PC 104 determines the irradiation range of the electron beam 15 in the processes of steps S9 and S17 described above, i.e., in the backscattered electron image acquisition process.

[0064] FIG. 5 is an image showing an example of the irradiation range of the electron beam 15 in the backscattered electron image acquisition process. As shown in Fig. 5, the PC 104 sets the irradiation range of the electron beam 15 to only the object 38 and the periphery of the object 38, i.e., the vicinity of the object 38. Hereinafter, the irradiation range that only includes the object 38 and the vicinity of the object 38 shown in Fig. 5 will be referred to as a specific scan. In other words, when acquiring a backscattered electron image, the PC 104 sets the irradiation range of the electron beam 15 to only an important region. This makes it possible to prevent the electron beam 15 from being irradiated onto unimportant parts when acquiring a backscattered electron image.

[0065] Therefore, compared to the conventional technique in which the electron beam 15 is irradiated onto the entire build surface 32a, the irradiation range of the electron beam 15 can be reduced, and the time required for the process of acquiring a backscattered electron image can be shortened. As a result, the throughput of the build process in the 3D additive manufacturing apparatus 1 can be shortened. Furthermore, since the time required to acquire a backscattered electron image can be shortened, the image resolution can also be improved.

[0066] 6 and 7 are enlarged images showing the irradiation range of the electron beam 15. FIG. 6 and 7, when setting the irradiation range of the electron beam 15, the PC 104 also sets the lengths of margins T1 and T2, which are within a predetermined length range from the outer edge of the model 38. The length of the margin T1 in the irradiation range shown in FIG. 6 is set shorter than the length of the margin T2 shown in FIG.

[0067] 6 and 7, by setting the irradiation range to include not only the molded object 38 but also the specified margins T1 and T2 around the molded object 38, it is possible to know the state of the powder material 32 (powder bed) near the boundary with the molded object 38. Here, the powder bed near the boundary of the molded object 38 has a significant impact on the recoating of the powder material 32 in the sintering area (melt area). Therefore, if a problem occurs with this recoating, information about the state of the powder bed near the boundary of the molded object 38 becomes important.

[0068] During the build process, the area near the sintering area becomes extremely hot. For example, if Ti64 is used as the powder material 32, the temperature reaches an average of 700 to 800°C. Therefore, the area near the sintering area is affected by the thermal expansion of the powder material 32. This thermal expansion can cause the sintering area of ​​the actual build 38 to not coincide with the scanning area. To address this thermal expansion, it is effective to include margins T1 and T2 around the build 38 in addition to the build 38 as the irradiation range of the electron beam 15, as shown in Figures 6 and 7.

[0069] The lengths of the margins T1 and T2 around the object 38 may be set by the PC 104 based on the object information, or may be arbitrarily set by the user.

[0070] FIG. 8 is an image showing another example of the irradiation range of the electron beam 15 in the backscattered electron image acquisition process. Furthermore, when setting the irradiation range of the electron beam 15, the PC 104 may set the entire printing surface 32a (entire meltable area) including the printing object 38 as the irradiation range of the electron beam 15 for a predetermined layer when printing the printing object 38, as shown in Fig. 8. Then, the PC 104 sets a layer to be subjected to a specific scan as shown in Fig. 5 and a layer to be subjected to an irradiation range that covers the entire printing surface 32a as shown in Fig. 8 (hereinafter referred to as an entire surface scan).

[0071] Note that, as shown in FIG. 8, if full-surface scanning is used, it takes longer to acquire a backscattered electron image, but it makes it possible to check the state of the powder bed. Then, if you want to check the state of the powder bed in a certain layer range during modeling, you set full-surface scanning only for the layer range you want to check, as shown in FIG. 8. For other layers, you set specific scanning, as shown in FIG. 5. That is, the PC 104 selects full-surface scanning or specific scanning depending on the layer for which a backscattered electron image is to be acquired, and sets the irradiation range. This makes it possible to shorten the total time required to acquire a backscattered electron image as much as possible when modeling the entire object 38, and also makes it possible to check the state of the powder bed in a specific layer.

[0072] The setting of which layer among all layers is to be subjected to the full scan or the specific scan may be set by the PC 104 based on the object information, or may be arbitrarily set by the user.

[0073] 9 and 10 are images showing other examples of the irradiation range of the electron beam 15 in the backscattered electron image acquisition process. 9 and 10, the PC 104 sets a specific scan and selected partial areas 32aA and 32aB of the entire surface of the printing surface 32a as the irradiation range (hereinafter referred to as a partial scan) for a predetermined layer when printing the object 38. In the example shown in Fig. 9, the lower half of the figure is the selected area 32aA, and in the example shown in Fig. 10, the right half of the figure is the selected area 32aB.

[0074] Then, the PC 104 selects a specific scan or a partial scan depending on the layer and sets the irradiation range. This makes it possible to shorten the time required to acquire a total backscattered electron image as much as possible when forming the entire object 38, and also makes it possible to check the state of the powder bed in a specified area (areas 32aA and 32aB) on a specified layer.

[0075] The setting of which layer among all layers is to be subjected to partial scanning or specific scanning may be set by the PC 104 based on the object information, or may be arbitrarily set by the user.

[0076] Fig. 11 is a diagram showing another example of modeling data 200A of the object 38 modeled by the above-described three-dimensional additive manufacturing apparatus 1. Fig. 12 is an image showing another example of the irradiation range of the electron beam 15 in the backscattered electron image acquisition process.

[0077] As shown in Fig. 11, the modeling data 200A includes multiple objects 38A and 38B with different shapes and sizes. When setting the irradiation range of the electron beam 15, in a predetermined layer, as shown in Fig. 12, only the predetermined object 38A and the vicinity of the object 38A among the multiple objects 38A and 38B are set as the irradiation range. The remaining objects 38B among the multiple objects 38B are not set as the irradiation range. Hereinafter, the irradiation range shown in Fig. 12 is referred to as a selected scan. Note that in layers other than the predetermined layer, a specific scan is set as shown in Fig. 5, in which all of the objects 38A and 38B are set as the irradiation range.

[0078] In the above example, a specific layer is set for selective scanning, but all layers may be set for selective scanning. Also, if a layer is not required, the entire surface does not need to be scanned.

[0079] Here, there are cases where it is not necessary to acquire a backscattered electron image for a known object 38B that has already been manufactured several times. In contrast, it is necessary to acquire a backscattered electron image for an object 38A that is manufactured relatively recently. When manufacturing such objects 38A and 38B in a single manufacturing process, performing the selective scan shown in FIG. 12 can improve throughput compared to using only the specific scan shown in FIG. 5.

[0080] The setting of which layer among all layers is to be the selected scan or the specific scan may be set by the PC 104 based on the object information, or may be arbitrarily set by the user.

[0081] FIG. 13 is a diagram showing another example of the modeling data 200B of the model 38 modeled by the above-described three-dimensional additive manufacturing apparatus 1. 13, a support portion 38C that contacts the building plate 22 is created below the object 38. When setting the irradiation range of the electron beam 15, the PC 104 does not perform the processes of acquiring a backscattered electron image (BSE image) in the processes of steps S9 and S17 described above for the layer where the support portion 38C is to be built. That is, the PC 104 does not set the irradiation range for the layer where the support portion 38C is to be built.

[0082] Here, the purpose of acquiring a backscattered electron image (BSE image) is basically to check the melting state of the model 38. Therefore, unless there is a special reason, there is almost no benefit to acquiring a backscattered electron image of the support part 38C. Therefore, as described above, by not performing the process of acquiring a backscattered electron image (BSE image) in the layer that forms the support part 38C, it is possible to shorten the throughput of the modeling process in the 3D additive manufacturing apparatus 1.

[0083] Note that the decision as to whether to perform processing to acquire a backscattered electron image (BSE image) in the layer in which the support portion 38C is to be formed may be made by the PC 104 or by the user.

[0084] FIG. 14 is a diagram showing another example of the modeling data 200C of the model 38 modeled by the above-described three-dimensional additive manufacturing apparatus 1. 14 includes normal-sized objects 38 and 38D, and an object 38E with a very small melting area. Hereinafter, the object 38E will be referred to as the extremely small area.

[0085] 15 and 16 are images showing the irradiation range of the electron beam 15 in the backscattered electron image acquisition process when forming the modeling data 200C in FIG. When setting the irradiation range of the electron beam 15, if the sizes of all of the objects 38, 38D exceed the threshold in a given layer when forming the objects 38, 38D, the PC 104 sets the irradiation range to include the objects 38, 38D and the vicinity of the objects 38, 38D, as shown in Fig. 15. On the other hand, in the case of an object 38E whose size is equal to or smaller than the threshold, i.e., a layer in which a minimal area exists, the PC 104 does not set the minimal area in the irradiation range, as shown in Fig. 16. Then, the PC 104 sets the irradiation range to include the object 38 whose size exceeds the threshold and the vicinity of the object 38.

[0086] As described above, the purpose of acquiring a backscattered electron image (BSE image) is basically to check the melting state of the model 38. In the case of a very small area whose size is equal to or smaller than a threshold, the melt area is small, so the probability of defects occurring due to insufficient melting is extremely small. Therefore, there is almost no benefit to acquiring a backscattered electron image of a very small area unless there is a special reason. Therefore, the very small area is excluded from the irradiation range of the electron beam 15. In this way, by not performing the process of acquiring a backscattered electron image (BSE image) for the very small area, the throughput of the modeling process in the 3D additive manufacturing device 1 can be shortened.

[0087] The threshold value for determining the minimum area may be set by the PC 104 based on the object information, or may be arbitrarily set by the user.

[0088] The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the spirit of the invention as set forth in the claims.

[0089] In addition, the irradiation range of the electron beam 15 when acquiring backscattered electrons may be set by the control unit PC 104, or may be set by the user, who then inputs the set irradiation range to the PC 104 and the memory unit 105 via an input unit connected to the PC 104 and the memory unit 105.

[0090] For example, in the above-described embodiment, an example has been described in which metal powder such as titanium, aluminum, or iron is used as the powder material, but the present invention is not limited thereto, and resin or the like may also be used as the powder material. Furthermore, an example has been described in which a beam irradiation device that irradiates an electron beam is used as the irradiation device, but the present invention is not limited thereto. For example, a laser irradiation device that irradiates a laser as a primary beam may also be used as the irradiation device.

[0091] Furthermore, some or all of the above-described components, functions, processing units, etc. may be implemented in hardware, for example, by designing an integrated circuit. Furthermore, the above-described components, functions, etc. may be implemented in software by a processor interpreting and executing a program that implements each function. Information such as the programs, tables, and files that implement each function can be stored in a storage device such as a memory, a hard disk, or an SSD (Solid State Drive), or in a storage medium such as an IC card, SD card, or DVD.

[0092] In this specification, the words "parallel" and "orthogonal" are used, but these do not mean only "parallel" and "orthogonal" in the strict sense, but also include "parallel" and "orthogonal" and may also mean a "substantially parallel" or "substantially orthogonal" state within a range in which the functions can be exerted. [Explanation of symbols]

[0093] 1...3D additive manufacturing device, 2...beam irradiation device, 3...vacuum chamber, 15...electron beam, 16...powder supply device, 16a...hopper, 16b...powder dropper, 16c...squeegee, 16d...blade, 18...build table, 20...build box, 21...recovery box, 22...build plate, 24...inner base, 26...plate movement device, 32...powder material, 32a...build surface, 32aA, 32aB...selected area, 38, 38A, 38B, 38D, 38E...model, 38C...support unit, 42...camera, 44...shutter, 46...detection unit, 101...polarization amplifier control circuit, 102...digital conversion circuit (ADC), 103...preamplifier (Pre-AMP) 104...personal computer (PC, control unit), 105...Memory section, 200, 200A, 200B, 200C...Modeling data, T1, T2...Margin

Claims

1. In a three-dimensional additive manufacturing apparatus for manufacturing a model, A shaping plate and a powder supplying device that supplies powder material to the build plate to form a powder layer; an irradiation device that irradiates the powder layer with a primary beam; a detection unit that detects electrons generated when the primary beam is irradiated onto the powder material; a control unit that controls the irradiation device, The control unit controls the irradiation device so that the primary beam is irradiated only onto a predetermined irradiation range in the powder layer when acquiring the electrons. 3D additive manufacturing device.

2. The irradiation range is set to the object and a predetermined length range from the outer edge of the object. The three-dimensional additive manufacturing apparatus according to claim 1 .

3. a storage unit in which modeling data for modeling the object is stored, The control unit sets the irradiation range when acquiring the electrons based on the modeling data. The three-dimensional additive manufacturing apparatus according to claim 2 .

4. The control unit determines, based on the modeling data, whether the modeled object is a known modeled object that has already been modeled several times or a new modeled object, and sets the irradiation range when acquiring the electrons. The three-dimensional additive manufacturing apparatus according to claim 3 .

5. When the control unit determines that the size of the object is equal to or smaller than a threshold based on the object forming data, the control unit excludes the object from the irradiation range when acquiring the electrons. The three-dimensional additive manufacturing apparatus according to claim 3 .

6. The control unit controls the irradiation device so that, when obtaining the electrons, the irradiation device irradiates the primary beam onto an entire meltable area in a predetermined layer among all layers used to form the object, and irradiates the primary beam only onto the predetermined irradiation range in other layers among all layers used to form the object. The three-dimensional additive manufacturing apparatus according to claim 1 .

7. The control unit does not irradiate a predetermined layer among all layers forming the object with the primary beam and does not perform the process of obtaining the electrons. The three-dimensional additive manufacturing apparatus according to claim 1 .

8. A control method for a three-dimensional additive manufacturing apparatus including a modeling plate, a powder supplying device that supplies powder material to the modeling plate to form a powder layer, an irradiation device that irradiates the powder layer with a primary beam, a detection unit that detects electrons generated when the primary beam irradiates the powder material, and a control unit that controls the irradiation device, The control unit controls the irradiation device so that the primary beam is irradiated only onto a predetermined irradiation range in the powder layer when acquiring the electrons. A method for controlling a three-dimensional additive manufacturing device.

Images