3D additive manufacturing system, its control method, and control program

Abstract

In order to perform shaping control in accordance with a molten state of a shaping surface in three-dimensional additive manufacturing, provided is a three-dimensional additive manufacturing system that performs additive manufacturing by using a shaping beam in a vacuum. The three-dimensional additive manufacturing system is characterized by comprising: a thermal electron detection unit that detects an amount of thermal electrons emitted from the shaping surface by irradiating the shaping surface with the shaping beam; and a control unit that controls the operation of the shaping beam in accordance with the amount of thermal electrons. Also provided are a control method therefor and a control program therefor.

Description

Technical Field

[0001] The present invention relates to a three-dimensional layer manufacturing system, a control method thereof, and a control program.

Background Art

[0002] In the above technical field, Patent Document 1 discloses a technique for preventing thermoelectrons emitted from a shaping surface from being deposited on the inner wall of a vacuum chamber by metal vapor generated during shaping from a molten portion or metal sputtering by fireworks, capturing them with an anti-deposition cover, detecting them as current by a voltage superposed current amplifier, and calculating the shaping surface temperature.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0007] To achieve the above object, the method according to the present invention is A control method for a three-dimensional laminated shaping system that performs laminated shaping using a shaping beam in a vacuum, A thermoelectron detection step of detecting the amount of thermoelectrons emitted from the shaping surface when the shaping beam is irradiated on the shaping surface, A control step of controlling the operation of the shaping beam according to the amount of the thermoelectrons, includes fruit, The control step is a control method for a three-dimensional additive manufacturing system, in which the irradiation position of the molding beam on the fabrication surface is moved at the timing when the amount of thermionic electrons at the irradiation position reaches a predetermined value.

[0008] To achieve the above object, the program according to the present invention is A control program for a three-dimensional laminated shaping system that performs laminated shaping using a shaping beam in a vacuum, A thermoelectron detection step of detecting the amount of thermoelectrons emitted from the shaping surface when the shaping beam is irradiated on the shaping surface, A control step of controlling the operation of the shaping beam according to the amount of the thermoelectrons, to be executed by a computer 、 The control step involves moving the irradiation position of the molding beam at the timing when the amount of thermionic electrons at the irradiation position of the molding beam on the molding surface reaches a predetermined value. It is a control program for a three-dimensional laminated shaping system.

Effects of the Invention

[0009] According to the present invention, shaping control according to the melting state of the shaping surface can be performed.

Brief Description of the Drawings

[0010] [Figure 1] It is a block diagram showing the configuration of a three-dimensional laminated shaping system according to the first embodiment. [Figure 2] This is a block diagram showing the configuration of a 3D additive manufacturing system according to the second embodiment. [Figure 3] This graph shows the relationship between the melting temperature and thermionic electron quantity at the irradiation position according to the second embodiment. [Figure 4] This is a flowchart showing the processing procedure of the 3D additive manufacturing system according to the second embodiment. [Figure 5] This figure shows the configuration of the conversion table according to the second embodiment. [Figure 6] This figure illustrates the overview of the 3D additive manufacturing system according to the third embodiment. [Figure 7] This is a block diagram showing the configuration of a 3D additive manufacturing apparatus according to the third embodiment. [Figure 8] This is a block diagram showing the configuration of a 3D additive manufacturing apparatus according to the fourth embodiment. [Figure 9] This is a block diagram showing the configuration of a 3D additive manufacturing apparatus according to the fifth embodiment. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the components described in the following embodiments are merely illustrative and are not intended to limit the technical scope of the present invention to them alone.

[0012] [First Embodiment] A three-dimensional additive manufacturing system 100 as a first embodiment of the present invention will be described with reference to Figure 1. The three-dimensional additive manufacturing system 100 is a system that performs additive manufacturing using a manufacturing beam in a vacuum.

[0013] As shown in Figure 1, the 3D additive manufacturing system 100 includes a thermionic electron detection unit 101 and a control unit 102. The thermionic electron detection unit 101 detects the amount of thermionic electrons 113 emitted from the manufacturing surface 112 when the manufacturing beam 111 (electron beam or laser) is irradiated onto the manufacturing surface 112.

[0014] The control unit 102 controls the operation of the shaping beam 111 according to the amount of thermionic electrons 113.

[0015] According to this embodiment, it is possible to control the molding process according to the melting state of the molding surface.

[0016] [Second Embodiment] Next, a three-dimensional additive manufacturing system 200 according to the second embodiment of the present invention will be described using Figures 2 and later. The three-dimensional additive manufacturing system 200 according to this embodiment detects the amount of thermionic electrons emitted from the manufacturing surface irradiated with a manufacturing beam. Thermionic electrons are detected by detecting the current output from a positively charged metal plate. In this embodiment, the metal plate is supported by an insulator on the build plate and positioned close to the manufacturing surface, while the connection between the metal plate and the current detection unit is positioned away from the manufacturing surface.

[0017] <Configuration and Operation of a 3D Additive Manufacturing System> Figure 2 is a block diagram showing the configuration of the 3D additive manufacturing system 200 according to this embodiment. The 3D additive manufacturing system 200 comprises an additive manufacturing apparatus 201, a thermionic detection unit 205, and a control unit 206.

[0018] (Configuration of additive manufacturing equipment) In the additive manufacturing apparatus 201, an electron gun 212 is mounted on a vacuum chamber 211, and a build frame (build box) 213 with a circular or rectangular cross-section is provided inside the vacuum chamber 211. A Z-drive mechanism 214 is located on the lower inside of the build frame 213, which allows the powder tray 215 to move in the Z direction (up and down). A heat-resistant flexible seal 216 is provided in the gap between the build frame 213 and the powder tray 215, providing sliding and sealing properties between the flexible seal 216 and the inner surface of the build frame 213. The inside of the vacuum chamber 211 is evacuated by a vacuum pump (not shown) and maintained under vacuum.

[0019] Unsintered metal powder 223 is spread on the powder tray 215, and a build plate 219 is positioned on top of it to create the object 218 in a raised state. The build plate 219 is grounded to the powder tray 215, which is at GND potential, by a GND wire 220 to prevent it from floating electrically. The additively fabricated object 218 is formed on the build plate 219, and as each layer is fabricated, a linear funnel 222 filled with metal powder 221 moves from left to right in the figure, spreading the metal powder 221 to approximately the same height as the top surface of the build frame base 213. Powder is replenished into the linear funnel 222 as needed from a powder hopper (not shown).

[0020] The surface layer of the spread metal powder 223 is melted two-dimensionally by the electron beam from the electron gun 212, and the resulting superposition constructs the object 218. On the build plate 219, the metal powder 224 spread in areas other than the object 218 is pre-sintered by the electron beam from the electron gun 212 and is electrically conductive.

[0021] A protective cover 225, grounded to GND, is installed between the build surface 232 and the electron gun 212 to prevent the deposition of metal vapors generated during build and metal sputter from the fireworks onto the inner wall of the chamber. The protective cover 225 also serves as a radiation shield from the high-temperature build surface.

[0022] A thermionic detector electrode 230 for thermionic detection is provided inside the protective cover 225. Thermionic detector electrode guides 231, to which thermionic detector electrodes 230 are attached via insulators 217, are mounted on both ends of the build frame 213, which has a small temperature rise during molding. Thermionic detector electrode 230 uses a metal electrode such as Ti, which has a small amount of secondary electron emission during electron excitation. The insulator 217, which electrically isolates the thermionic detector electrode 230 from the ground potential, is positioned far from the build surface 232 to suppress the decrease in insulation resistance due to temperature rise.

[0023] A voltage-superimposed current amplifier 251 is connected to the thermionic electron detection electrode guide 231 via a current introduction terminal 228. The voltage-superimposed current amplifier 251 is a circuit that converts the amount of thermionic electrons drawn in by the thermionic electron detection electrode 230 into an electric current. A low voltage of a few volts or less is applied to the voltage-superimposed current amplifier 251 so as to have almost no effect on the primary electron beam relative to GND, and so as to attract only thermionic electrons with lower energy than secondary electrons. As a result, thermionic electrons emitted from the melting point of the fabricated object 218 are drawn to the thermionic electron detection electrode 230 by a positive potential gradient, and the amount of these electrons is detected as an electric current.

[0024] By applying a positive voltage, the detection efficiency of thermionic electrons can be improved even when the electron beam is OFF or during laser beam melting. Furthermore, the applied voltage can be changed depending on whether the temperature is relatively low or high. For example, by increasing the positive voltage at relatively low temperatures and decreasing it at high temperatures, the system can be used across the entire temperature range without changing the gain of the current amplifier. In other words, thermionic electrons are detected by an electrode 230, which is a positively charged metal plate supported by an insulator 217 on the build frame 213 and positioned close to the build surface, and a current detection unit 251 that detects the current output from the electrode 230. The connection point 228 to the current detection unit 251 is positioned away from the build surface 232.

[0025] In the configuration shown in Figure 2, the anti-adhesion cover 225 is suspended below the electron gun 212. However, the present invention is not limited to this configuration. Alternatively, a GND potential guide may be placed on the thermionic detection electrode guide 231 via an insulator, and the anti-adhesion cover 225 may be mounted on top of that guide. This allows the thermionic detection electrode 230 and the anti-adhesion cover 225 to be mounted together on the build surface.

[0026] The thermionic detection unit 205 includes a voltage-superimposed current amplifier 251, an A / D conversion unit 252, and a thermionic quantity acquisition unit 253. The A / D conversion unit 252 converts the analog current value, which is the output of the voltage-superimposed current amplifier 251, into a digital current value. The thermionic signal generation unit 253 then generates a thermionic signal corresponding to the thermionic quantity and sends it to the control unit 206.

[0027] The control unit 206 includes a comparator 261 for comparing the thermionic image signal with a set value, a scan generator 262, and a deflection amplifier 263, and is connected to the deflector (deflection coil) 229 in the electron gun 212. The control unit 206 controls the operation of the electron beam or laser according to the calculated dwell time (timing). In other words, the control unit 206 moves the irradiation position at a dwell time (timing) estimated to be when the amount of thermionic electrons at the irradiation position of the electron beam or laser on the build surface reaches a predetermined value. Alternatively, the control unit 206 moves the irradiation position at a speed at which the amount of thermionic electrons at the irradiation position of the electron beam or laser on the build surface does not reach a predetermined value. Instead of dwell time, the beam current may be changed.

[0028] (operation) The shaping sequence involves a "squeegeeing process" to spread the powder, a "preheating process" to heat the spread powder, a "melting process" for the shaping area, and an "afterheating process" to prepare for the next squeegeeing. This process is repeated for each layer to create the object.

[0029] At the start of the squeegeeing process, the powder tray 215 is lowered by the Z-drive mechanism 214 so that the upper surface of the build plate 219 is positioned slightly lower than the upper surface of the build frame base 213. This slight lowering of ΔZ corresponds to the subsequent layer thickness in the Z direction. The linear funnel 222 filled with metal powder 221 is moved along the upper surface of the build plate 219 to the opposite side (right side in the figure), and the metal powder 221 equivalent to ΔZ is spread on and around the build plate 219.

[0030] In the preheating process, the metal powder 221 spread on the build plate 219 is heated by irradiating an area slightly smaller than the build plate 219 with an electron beam from the electron gun 212, thereby pre-sintering it.

[0031] In the melting process, the electron beam from the electron gun 212 melts the two-dimensional shape of the pre-prepared design object, which has been sliced ​​at ΔZ intervals. The electron beam is scanned according to a pre-set campus, and each point is melted using a pre-set beam current, beam diameter, and scanning speed (determined by the dwell time at one point and the distance to the next point). A thermionic signal from the voltage-superimposed current amplifier 251 is detected while each point is being melted.

[0032] The beam is irradiated at the starting point of the scan, and the comparison unit 261 compares the set value of the thermionic electron signal with the thermionic electron signal from the thermionic electron detection unit 205. The moment the thermionic electron signal reaches the set value, a trigger signal is input to the scan generator 262, and the electron beam moves in the scan direction by the scan pitch (SP). Similarly, at the next point, it stays at that position until the thermionic electron signal reaches the set value, and then moves to the next point. In this way, the movement is repeated point by point until the thermionic electron signal reaches the set value, melting the two-dimensional shape.

[0033] In the afterheating process, the build surface 232 of the build plate 219, which is covered with the spread powder 224, is positioned at approximately the same height as the top surface of the build frame base 213. The electron beam from the electron gun 212 is irradiated onto a slightly narrower area than the entire top surface of the build plate 219, preheating it to a temperature at which the metal powder 221 pre-sintersects. This suppresses the scattering of metal powder 221 due to charge-up.

[0034] In the example of the 3D additive manufacturing system 200, the additive manufacturing device 201 and the control unit 206 are shown as being located in close proximity. However, the additive manufacturing device 201 and the control unit 206, or a part of the control unit 206, may be located remotely and communicate with each other via wired or wireless connections.

[0035] <Reasons why thermionic electrons are detected at the melting point> Figure 3 is a graph showing the relationship between the melting temperature at the irradiation position and the amount of thermionic electrons. Figure 3 shows the results of calculating thermionic electrons generated from a φ0.5 mm region in a Ti64 alloy as a function of temperature. As can be seen from Figure 3, the amount of thermionic electrons increases exponentially with increasing temperature. For example, in the case of Ti64, the fabrication surface is heated to about 750°C during preheating, and the amount of thermionic electrons emitted from the entire region is about 0.5 pA (picoamperes). In contrast, thermionic electron emission from a φ0.5 mm region at the melting point (about 1650°C) is about 1 μA (microamperes), it becomes about 100 μA (microamperes) when the melting temperature is about 2000°C, and more than 4 mA (milliamperes) of thermionic electrons are generated when the temperature is about 2400°C.

[0036] On the other hand, thermionic electrons emitted when heating the build surface during preheating and afterheating are emitted when the build surface is 110 x 110 mm. 2 In that case, even if the temperature is 1000°C, the current is small, around 20 nA (nanoamperes). When molten, the temperature of all parts except the melting point is lower, so the thermionic electrons detected during moltenness will reflect the temperature of the melting point (melt pool), which is high.

[0037] <Processing procedure for 3D additive manufacturing system> Figure 4 is a flowchart showing the processing procedure of the 3D additive manufacturing system 200. This flowchart shows how the components in Figure 2 are implemented so that the CPU (Central Processing Unit) of the control unit 206 uses RAM (Random Access Memory) to operate the 3D additive manufacturing device.

[0038] In step S401, the control unit 206 waits for the acquisition of additive manufacturing data. Once the acquisition of additive manufacturing data is complete, in step S403, it instructs the additive manufacturing apparatus 201 to squeegee the additive manufacturing powder.

[0039] Once squeegeeing is complete, the additive manufacturing apparatus 201 is instructed in step S405 to perform preheating to heat the laid powder.

[0040] Once preheating is complete, in step S407, the control unit 206 instructs the additive manufacturing apparatus 201 to "melt" the materialization area. In step S409, the control unit 206 instructs the additive manufacturing apparatus 201 to perform "afterheating (AH)" in preparation for the next squeegeeing. The additive manufacturing apparatus 201 positions the materialization surface 232 at approximately the same height as the top surface of the build frame base 213, irradiates it with an electron beam from the electron gun 212, and heats it to a temperature at which the metal powder 221 pre-sintersects.

[0041] Once after-heating is complete, the control unit 206 instructs the additive manufacturing apparatus 201 in step S411 to lower the build plate by one layer. In step S413, it is determined whether or not the additive manufacturing is complete. If it is not complete, the process returns to step S403 and the manufacturing of the next layer is repeated. In step S407, during the "melting" of the build area, the processes in steps S471 to S477 are performed as the build surface monitoring method of this embodiment.

[0042] In step S471, the control unit 206 acquires the thermionic signal at the melting point. In step S473, the control unit 206 compares the acquired thermionic signal with a set value. If the thermionic signal exceeds the set value, the process proceeds to step S475, where melting control is performed to move to the next melting point. The set value is derived in advance from a conversion table between thermionic signal and temperature, and the deflector 229 is controlled to keep the melting temperature constant. Even in dot melting where the canvas is not defined, the timing of moving to the next point is set to coincide with the timing when the value of the thermionic signal becomes constant. By controlling the thermionic emission during melting to be constant, the melting temperature can be kept constant, enabling uniform melting within the fabricated surface and leading to defect suppression.

[0043] (Conversion Table) Figure 5 shows an example of a conversion table for calculating the set value. The conversion table is used to convert the amount of thermionic electrons to the melting temperature. The conversion table is generated as follows: The relationship between the temperature T of a radiation thermometer or the like and the thermionic current I detected by the voltage superimposed current amplifier 251 is measured in advance, and a and b are determined as constants by fitting them with the following equation (1). I = a·T 2 ·e b / T (1) Alternatively, in the expanded equation as shown in equation (2), the relationship between ln(I / T²) and 1 / T can be plotted, and a and b can be determined from the slope b and intercept ln a of the resulting linear equation. The linear equation in this case can be found relatively easily using the least squares method or similar. ln (I / T 2 ) = b·1 / T + ln a (2) Using equation (1) from which a and b were obtained, the relationship between thermionic current and temperature is determined and converted to temperature.

[0044] Furthermore, since the above measurements are difficult to perform at the molten state, a sufficiently large area is scanned, and the temperature and thermionic electrons from that area are measured. The area is then expanded to a melt size such as the beam size, and the relationship between temperature and thermionic electrons in the required spot area is determined. In addition, once the relationship between temperature and thermionic electrons is determined, the thermionic electron signal for the required temperature is calculated in advance as a threshold value, and by using this value as a parameter, a melting process at the required melting temperature can be achieved.

[0045] By using such a conversion table, the value of thermionic electrons that should move the electron beam to the next point can be determined from the upper limit temperature at the melting point, and this value of thermionic electrons can be set as a default value. Alternatively, multiple such default values ​​can be stored according to the type of metal powder, and these can be read out and used according to the metal powder information entered before fabrication.

[0046] As described above, in this embodiment, the scan attributes (scan pitch, scan speed, line pitch, etc.) are controlled according to the value of the thermionic signal. The value of the thermionic signal at each melting point is kept constant. For each melting point, the residence time of the electron beam is changed so that the integrated value of the thermionic signal remains constant.

[0047] This makes it possible to easily and accurately maintain a constant melting temperature at each melting point on the molded surface, thereby improving the quality of the molded product.

[0048] Furthermore, since electron beams do not respond quickly to current control, it is more effective to change the timing or scan speed rather than the current value. On the other hand, when using a laser, power control (controlling the pulse width) is also an option. In addition, by making the scan pitch finer, variations in the melting temperature across the entire fabricated surface can be further reduced.

[0049] Conventionally, control methods that maintain a constant electron beam residence time at each melting point, or that apply empirically determined corrections to the residence time near the turning point, have not been able to achieve optimal melting control for complex shapes or fabricated surfaces with varying powder particle densities at different points. However, according to this embodiment, even fabricated objects under such conditions can be manufactured with high quality.

[0050] [Third Embodiment] Next, a three-dimensional additive manufacturing system according to a third embodiment of the present invention will be described with reference to Figures 6 and 7. The three-dimensional additive manufacturing system according to this embodiment differs from the second embodiment in that it uses simulation control instead of feedback control. Other configurations and operations are the same as in the second embodiment, so the same reference numerals are used for the same configurations and operations, and their detailed descriptions are omitted.

[0051] When the amount of thermionic electrons generated is simulated according to the fabrication conditions, it shows good agreement with the thermionic image. For example, a simulation image can be generated in which the intensity changes line by line, as shown in image 601 in Figure 6. Therefore, the residence time of the electron beam at each point is calculated so that a thermionic image 602 without intensity changes is output. As a result, the residence time of the electron beam at each point on the fabrication surface is as shown in image 603. Fabrication is then carried out by controlling the melt according to the residence times calculated in this way.

[0052] In other words, thermionic images in the melting process are simulated to determine the input energy (such as residence time or beam current) at each melting point so that the amount of thermionic electrons at each point reaches a set value (constant value). A canvas with that input energy is then created, and melting control is performed under those conditions.

[0053] Figure 7 shows the configuration of the 3D additive manufacturing system 700 of this embodiment. The control unit 706 of the 3D additive manufacturing system 700 has a storage unit 761, a thermionic electron estimation unit 762, and a timing calculation unit 763. The storage unit 761 stores the thermionic electron images detected by the thermionic electron detection unit 205 in association with the manufacturing data (electron beam scan trajectory data).

[0054] The thermionic electron estimation unit 762 estimates the thermionic electron image by referring to the data stored in the memory unit 761. For example, when repeatedly fabricating the same (or similar) object, the thermionic electron image can be estimated using the thermionic electron signals detected in the past.

[0055] The timing calculation unit 763 calculates the residence time (timing) using the estimated thermionic image. Since the timing calculation unit 763 outputs a trigger signal at the calculated timing, a comparator or similar device is not required, and the trigger signal is directly input to the scan generator 262.

[0056] The control unit 206 controls the operation of the electron beam or laser according to the calculated dwell time (timing). In other words, the control unit 206 moves the irradiation position at a dwell time (timing) estimated to be when the amount of thermionic electrons at the irradiation position of the electron beam or laser on the fabrication surface reaches a predetermined value. Alternatively, the control unit 206 moves the irradiation position at a speed that prevents the amount of thermionic electrons at the irradiation position of the electron beam or laser on the fabrication surface from reaching a predetermined value. Instead of dwell time, the beam current may be changed.

[0057] This allows for control over the melting process to ensure a constant melting temperature regardless of the size or location of the melting area. Furthermore, optimizing the melting temperature enables the creation of consistently high-quality molded objects.

[0058] [Fourth Embodiment] Next, a three-dimensional additive manufacturing apparatus according to the fourth embodiment of the present invention will be described using Figure 8. The three-dimensional additive manufacturing apparatus according to this embodiment differs from the second and third embodiments in that it combines feedback control (second embodiment) and simulation control (third embodiment). Other configurations and operations are the same as in the second embodiment, so the same reference numerals are used for the same configurations and operations, and their detailed descriptions are omitted.

[0059] For example, this embodiment is effective when the shape is complex and it is difficult to perfectly reproduce the thermionic signals in simulation. For instance, in the fabrication area, the inner portion where the thermionic signal estimation accuracy is high is calculated in advance and controlled, while the outer portion where the estimation accuracy is thought to be low is compared with a set value of thermionic signals detected in real time.

[0060] Figure 8 shows the configuration of the 3D additive manufacturing system 800 of this embodiment. The 3D additive manufacturing system 800 includes a timing calculation unit 763 and a selection unit 864.

[0061] The timing calculation unit 763 estimates the amount of thermionic electrons emitted from the fabrication surface during fabrication through simulation. The selection unit 864 selects either the estimated residence time (timing) or the timing at which the detected thermionic electron signal reaches a set value, according to a preset criterion, for each region on the fabrication surface, and passes it to the scan generator 262.

[0062] The selection unit 864, for example, selects the dwell time (timing) from the timing calculation unit 763 near the center of the build surface 232, and selects the timing from the comparator 261, which outputs the timing at which the actual thermionic signal reaches a set value, near the periphery of the build surface 232. Conversely, the selection unit 864 may select the timing signal from the timing calculation unit 763 near the periphery of the build surface 232, and the timing signal from the comparator 261 near the center of the build surface 232. For example, the complexity may be determined for each region of the build surface, and in regions where the complexity is greater than or equal to a predetermined value, the timing signal from the comparator 261 based on the actual thermionic signal may be selected, and in regions where the complexity is less than a predetermined value, the timing signal from the timing calculation unit 763 may be selected.

[0063] According to this embodiment, the melting process can be controlled with greater precision to ensure a constant melting temperature regardless of the size or location of the melting area. Furthermore, by optimizing the melting temperature, it is possible to consistently produce molded objects of stable quality.

[0064] [Fifth Embodiment] Next, a 3D additive manufacturing apparatus according to the fifth embodiment of the present invention will be described using Figure 9. The 3D additive manufacturing apparatus 900 according to this embodiment differs from the third embodiment in that it estimates thermionic images using artificial intelligence. Other configurations and operations are the same as in the third embodiment, so the same reference numerals are used for the same configurations and operations and their detailed descriptions are omitted.

[0065] The machine learning unit 961 performs machine learning using the thermionic signals detected by the thermionic detection unit 205 and the correspondence between thermionic image data and fabrication data stored in the external database 970 as training data to generate a thermionic image estimation model. The thermionic estimation unit 962 estimates the thermionic image using the generated thermionic image estimation model.

[0066] According to this embodiment, the melting process can be controlled with greater precision to ensure a constant melting temperature regardless of the size or location of the melting area. Furthermore, by optimizing the melting temperature, it is possible to consistently produce molded objects of stable quality.

[0067] [Other embodiments] The above embodiment shows the case of an electron beam type PBF, but similarly, the melting temperature can be measured by thermionic electrons during melting with wire or powder type DEDs. Similarly, with laser types, thermionic electron measurement can be performed in a vacuum, allowing for the measurement of the melting temperature during melting. In the case of laser beam melting, thermionic electrons are also detected during beam irradiation.

[0068] Furthermore, although the present invention has been described above with reference to embodiments, the present invention is not limited to the above embodiments. Various modifications to the structure and details of the present invention can be made, as can be understood by those skilled in the art within the technical scope of the present invention. In addition, any system or apparatus that combines the separate features included in each embodiment is also within the technical scope of the present invention.

[0069] Furthermore, the present invention may be applied to a system composed of multiple devices or to a single device. Moreover, the present invention is also applicable when an information processing program that realizes the functions of the embodiment is supplied to a system or device and executed by a built-in processor. The technical scope of the present invention includes programs installed on a computer to realize the functions of the present invention on a computer, or a medium storing such a program, a server that downloads such a program, and a processor that executes such a program. In particular, at least a non-transitory computer-readable medium storing a program that causes a computer to execute the processing steps included in the embodiments described above is included in the technical scope of the present invention.

Claims

1. A three-dimensional additive manufacturing system that performs additive manufacturing using a shaping beam in a vacuum, A thermionic electron detection unit detects the amount of thermionic electrons emitted from the surface of the material being created when the molding beam is irradiated onto the surface of the material being created. A control unit that controls the operation of the molding beam according to the amount of thermionic electrons, Equipped with, The control unit is a three-dimensional additive manufacturing system that moves the irradiation position of the molding beam on the fabrication surface when the amount of thermionic electrons at the irradiation position reaches a predetermined value.

2. A three-dimensional additive manufacturing system that performs additive manufacturing using a shaping beam in a vacuum, A thermionic electron detection unit detects the amount of thermionic electrons emitted from the surface of the material being created when the molding beam is irradiated onto the surface of the material being created. A control unit that controls the operation of the molding beam according to the amount of thermionic electrons, Equipped with, The control unit moves the irradiation position of the molding beam on the molding surface at a speed such that the amount of thermionic electrons at the irradiation position does not reach a predetermined value.

3. A three-dimensional additive manufacturing system that performs additive manufacturing using a shaping beam in a vacuum, A thermionic electron detection unit detects the amount of thermionic electrons emitted from the surface of the material being created when the molding beam is irradiated onto the surface of the material being created. A control unit that controls the operation of the molding beam according to the amount of thermionic electrons, The simulation includes an estimation unit that estimates the amount of thermionic electrons emitted from the fabricated surface during fabrication, and Equipped with, The control unit controls the operation of the molding beam according to the estimated amount of thermionic electrons in the three-dimensional additive manufacturing system.

4. A three-dimensional additive manufacturing system that performs additive manufacturing using a shaping beam in a vacuum, A thermionic electron detection unit detects the amount of thermionic electrons emitted from the surface of the material being created when the molding beam is irradiated onto the surface of the material being created. A control unit that controls the operation of the molding beam according to the amount of thermionic electrons, The simulation includes an estimation unit that estimates the amount of thermionic electrons emitted from the fabricated surface during fabrication, and Equipped with, The control unit controls the operation of the building beam according to the estimated amount of thermionic electrons, and moves the irradiation position when the amount of thermionic electrons at the irradiation position of the building beam on the building surface reaches a predetermined value, in a three-dimensional additive manufacturing system.

5. A three-dimensional additive manufacturing system that performs additive manufacturing using a shaping beam in a vacuum, A thermionic electron detection unit detects the amount of thermionic electrons emitted from the surface of the material being created when the molding beam is irradiated onto the surface of the material being created. A control unit that controls the operation of the molding beam according to the amount of thermionic electrons, The simulation includes an estimation unit that estimates the amount of thermionic electrons emitted from the fabricated surface during fabrication, and Equipped with, The control unit controls the operation of the building beam according to the estimated amount of thermionic electrons, and moves the irradiation position at a speed such that the amount of thermionic electrons at the irradiation position of the building beam on the building surface does not reach a predetermined value.

6. The thermionic electron detection unit is A positively charged metal plate, A current detection unit that detects the current output from the metal plate, A three-dimensional additive manufacturing system according to claim 1, comprising:

7. The three-dimensional additive manufacturing system according to claim 6, wherein the metal plate is supported by an insulator on the build plate and positioned close to the build surface, and the connection between the metal plate and the current sensing unit is positioned away from the build surface.

8. A control method for a three-dimensional additive manufacturing system that performs additive manufacturing using a manufacturing beam in a vacuum, The process includes a thermionic detection step in which the amount of thermionic electrons emitted from the surface of the material being fabricated is detected when the fabrication beam is irradiated onto the fabrication surface, A control step that controls the operation of the molding beam according to the amount of thermionic electrons, Includes, The control step is a control method for a three-dimensional additive manufacturing system, in which the irradiation position of the molding beam on the fabrication surface is moved at the timing when the amount of thermionic electrons at the irradiation position reaches a predetermined value.

9. A control program for a 3D additive manufacturing system that performs additive manufacturing using a manufacturing beam in a vacuum, The process includes a thermionic detection step in which the amount of thermionic electrons emitted from the surface of the material being fabricated is detected when the fabrication beam is irradiated onto the fabrication surface, A control step that controls the operation of the molding beam according to the amount of thermionic electrons, Have the computer run it, The control step is a control program for a three-dimensional additive manufacturing system that moves the irradiation position of the molding beam on the fabrication surface when the amount of thermionic electrons at the irradiation position reaches a predetermined value.

Images