Metal deposition modeling apparatus

Abstract

This metal deposition modeling apparatus (100) is provided with: a powder container (16) that retains a metal powder (25); a modeling plate (19) that is disposed in a modeling region (11) which is irradiated with an electron beam; and a squeegee (13) that moves the metal powder (25) supplied from the powder container (16) to the modeling plate (19) and evenly spreads the metal powder (25) so as to form a powder bed (12). This metal deposition modeling apparatus (100) forms a three-dimensional model by irradiating the metal powder (25) in the modeling region (11) with an electron beam, and melting and solidifying the metal powder (25). An oxide film removal part for removing an oxide film on the surface of the metal powder (25) by applying a kinetic energy to the metal powder (25) is provided in the flow path of the metal powder (25) from the outlet of the powder container (16) to the squeegee (13).

Description

Metal additive manufacturing equipment

[0001] The present disclosure relates to a metal additive manufacturing apparatus using an electron beam.

[0002] In metal additive manufacturing (AM) using an electron beam as a heat source, metal powder is irradiated with an electron beam to form a metal object. Metal powder is inherently a conductive material, but its specific surface area is large, and an oxide film several tens of nanometers thick forms on its surface. If an oxide film forms on the metal powder, when a powder bed is formed, the metal powder particles do not come into contact with each other, resulting in high insulation resistance from the electron beam irradiation area to the ground placed on the build plate, resulting in a lack of conductivity.

[0003] In Patent Document 1, in order to prevent the metal powder from becoming charged, a plasma source is installed in a vacuum chamber, and ions that are ionized in a manner opposite to the charging of the metal powder are emitted from the plasma source, thereby electrically neutralizing the powder bed.

[0004] Special Publication No. 2020-514957

[0005] In Patent Document 1, the electric circuit and electrodes serving as the ion source are installed near the trajectory of the electron beam, which may interfere with the trajectory of the electron beam when the electron beam is irradiated.

[0006] The present disclosure has been made in consideration of the above, and aims to provide a metal additive manufacturing device that can remove an oxide film from metal powder without interfering with the irradiation of an electron beam, and enable grounding conductivity in the area irradiated by the electron beam.

[0007] To solve the above-mentioned problems and achieve the object, the present disclosure provides a metal additive manufacturing apparatus comprising: a powder container for storing metal powder; a build plate disposed in a build region where an electron beam is irradiated; and a squeegee for moving and spreading the metal powder supplied from the powder container to the build plate to form a powder bed. The metal additive manufacturing apparatus irradiates the metal powder in the build region with an electron beam to melt and solidify the metal powder, thereby manufacturing a three-dimensional object. The metal powder flow path from the outlet of the powder container to the squeegee is characterized by including an oxide film removal unit that applies kinetic energy to the metal powder to remove an oxide film on the surface of the metal powder.

[0008] The metal additive manufacturing device of the present disclosure has the effect of removing an oxide film from metal powder without interfering with the irradiation of the electron beam, and enabling ground conduction in the area irradiated with the electron beam.

[0009] FIG. 1 is a diagram showing the configuration of a metal additive manufacturing apparatus according to a first embodiment. FIG. 2 is a diagram showing the configuration of a manufacturing unit of a metal additive manufacturing apparatus according to a first embodiment. FIG. 3 is a diagram showing the configuration of a metal additive manufacturing apparatus according to a second embodiment. FIG. 4 is an enlarged view of the configuration of a powder processing device of a metal additive manufacturing apparatus according to a second embodiment. FIG. 5 is a cross-sectional view of the configuration of a powder processing device of a metal additive manufacturing apparatus according to a second embodiment. FIG. 6 is a cross-sectional view of the configuration of a powder processing device of a metal additive manufacturing apparatus according to a third embodiment. FIG. 10 is a diagram showing the configuration of a device; FIG. 11 is a perspective view showing the configuration of a powder processing device arranged in a metal additive manufacturing apparatus according to a fifth embodiment; FIG. 12 is a plan view showing the configuration of a powder processing device arranged in a metal additive manufacturing apparatus according to a fifth embodiment; FIG. 13 is a perspective view showing a certain rotation state of a rotor in a powder processing device arranged in a metal additive manufacturing apparatus according to a fifth embodiment; FIG. 14 is a perspective view showing another rotation state of a rotor in a powder processing device arranged in a metal additive manufacturing apparatus according to a fifth embodiment;

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A metal additive manufacturing apparatus according to an embodiment will be described in detail below with reference to the accompanying drawings.

[0011] First Embodiment Fig. 1 is a diagram showing the configuration of a metal additive manufacturing apparatus 100 according to the first embodiment. Fig. 2 is a diagram showing the configuration of a manufacturing unit 45 of the metal additive manufacturing apparatus 100 according to the first embodiment. The metal additive manufacturing apparatus 100 includes a vacuum chamber 14, an electron gun 15, a vacuum pump 21, and a control device 22. A metal powder supply unit 40 and a manufacturing unit 45 are disposed within the vacuum chamber 14. The metal powder supply unit 40 includes a powder container 16, a powder passage 17, an ultrasonic blade 27 as a vibrating member, an ultrasonic vibrator 18 as a vibration source, and a powder measuring device 23. The manufacturing unit 45 includes a powder supply table 9, a squeegee 13, a manufacturing plate 19, and an elevation stage 24.

[0012] In the metal additive manufacturing apparatus 100, the metal powder 25 is supplied to the manufacturing region 11 and then spread evenly. In the metal additive manufacturing apparatus 100, the metal powder 25 is melted by irradiating the metal powder 25 with an electron beam, and then the molten metal powder 25 is solidified. The metal additive manufacturing apparatus 100 repeats these operations to manufacture a three-dimensional object 29, which is a three-dimensional object formed by depositing the molten and solidified metal powder 25.

[0013] The powder container 16 stores the metal powder 25. The powder measuring device 23 measures the metal powder 25 supplied from the powder container 16 and supplies it to the powder supply table 9. A plurality of powder passages 17 are provided between the powder container 16 and the powder measuring device 23. The powder passages 17 are flow paths for supplying the metal powder 25 from the powder container 16 to the powder measuring device 23. An ultrasonic blade 27 is provided inside the powder passage 17. The ultrasonic blade 27 transmits ultrasonic vibrations from the ultrasonic vibrator 18 to the metal powder 25 passing through the powder passage 17. The ultrasonic vibrator 18 and the ultrasonic blade 27 are provided in the flow path of the metal powder 25 from the outlet of the powder container 16 to the squeegee 13, and function as an oxide film removing unit that applies kinetic energy to the metal powder 25 to remove oxide films on the surfaces of the metal powder 25.

[0014] Metal powder 25 measured by a powder measuring device 23 is placed on the powder supply table 9. The squeegee 13 has a blade that transports the metal powder 25 on the powder supply table 9 to the building region 11 and spreads and levels the powder bed 12 to a uniform thickness.

[0015] The lifting stage 24 moves the powder bed 12 and the build plate 19 up and down coaxially with the central axis 26 of the electron beam. Metal powder 25 is spread on the powder bed 12. As shown in FIG. 2 , the powder bed 12 covers the entire periphery (top, bottom, left, right, front, back) of the build plate 19. The build region 11 is an area scanned by the electron beam emitted from the electron gun 15 and corresponds to the build plate 19. The build plate 19 serves as a base for the object 29 to be built. The object 29 is built on the build plate 19. The build plate 19 and the lifting stage 24 are connected by an earth ground 20.

[0016] The electron gun 15 emits an electron beam. The vacuum pump 21 exhausts gas inside the vacuum chamber 14 to the outside of the vacuum chamber 14. The control device 22 controls the components inside the vacuum chamber 14, the electron gun 15, the vacuum pump 21, etc.

[0017] Next, the operation of the metal additive manufacturing apparatus 100 according to the first embodiment will be described. In the initial state, the vacuum chamber 14 is open to the atmosphere, and the lifting stage 24, the powder bed 12, and the build plate 19 are in the positional relationship shown in Fig. 1. Next, with metal powder 25 stored in the powder container 16, the vacuum chamber 14 is lowered from atmospheric pressure to 100°C. －３ The pressure is reduced to about Pa. Then, electrons accelerated to 60 kV are irradiated onto the shaping region 11 from the electron gun 15. When the electrons collide with the shaping plate 19, their kinetic energy is converted into thermal energy, and the temperature of the shaping plate 19 gradually rises from room temperature. The energy of the electron beam irradiation at this time varies depending on the material of the metal powder 25 used. After reaching a certain temperature, which varies depending on the material of the metal powder 25, heat is transferred from the shaping plate 19 to each component in the vacuum chamber 14 by radiative heat transfer or thermal conduction, and the temperature rise of each component stops within several minutes to several tens of minutes.

[0018] Next, the metal powder 25 stored in the powder container 16 passes through the powder passage 17, where a certain amount is measured out by the powder measuring device 23, and then transported to the powder supply table 9. As the metal powder 25 passes through the powder passage 17, the ultrasonic vibrator 18 is operated by the control device 22. When the ultrasonic vibrator 18 is operated, the ultrasonic blade 27 vibrates ultrasonically, thereby applying ultrasonic vibrations to the metal powder 25 passing through the inside of the powder passage 17. This causes repeated collisions and friction between the particles of the metal powder 25. This collision and friction between the particles of the metal powder 25 removes an oxide film that is distributed on the surface of the metal powder 25 with a thickness of several nanometers to several tens of nanometers, and the material of the metal powder 25 is exposed on the surface of the metal powder 25.

[0019] The gap between the wall surface of the powder passage 17 and the ultrasonic blade 27 is adjusted according to the particle size of the metal powder 25 used. For example, if the particle size of the metal powder 25 used is 50 μm to 100 μm, the clearance should be 110 μm, and if the particle size of the metal powder 25 used is 20 μm to 60 μm, the clearance should be 70 μm. In this way, it is desirable that the gap between the ultrasonic blade 27 and the wall surface of the powder passage 17 be larger than the maximum particle size of the metal powder 25 and not more than 1.1 times the particle size of the metal powder 25. In practice, since it is difficult to control the narrow gap of the powder passage 17, ultrasonic blades 27 of different thicknesses are used depending on the metal powder 25 used.

[0020] Next, the metal powder 25 transported from the powder metering device 23 to the powder supply table 9 is moved toward the build region 11 by the squeegee 13, forming a uniform deposit layer 28 with a thickness of 20 μm to 100 μm on the build region 11, as shown in FIG. 2 . The thickness of the deposit layer 28 can be determined arbitrarily by the operator as one of the build conditions. The squeegee 13 reciprocates within the range indicated by arrow K1 at a speed arbitrarily set by the operator. Next, the control device 22 activates the electron gun 15, which irradiates the deposit layer 28 with an electron beam. The area of ​​the deposit layer 28 in the build region 11 irradiated with the electron beam melts and solidifies, bonding it to the underlying object 29 to form the object 29.

[0021] When forming the object 29, the electron gun 15 receives a command from the control device 22 and scans the electron beam within the fabrication area 11. The pattern of the scanning electron beam is tomographic data obtained by arranging 3D CAD (Three Dimensional Computer Aided Design) data of the object to be fabricated within the fabrication area 11 and slicing it for each thickness of the deposition layer 28. This method is the same as a general powder bed fused deposition modeling method.

[0022] When forming the next layer, the lift stage 24 is lowered in the downward direction opposite to the stacking direction K2 by a distance equal to the thickness of the deposition layer 28. After this, the above-described operation is performed to form the next layer. This operation is repeated for the number of layers to be stacked.

[0023] As described above, in the first embodiment, the flow path of the metal powder 25 from the outlet of the powder container 16 to the squeegee 13 is provided with an ultrasonic blade 27 as a vibrating member and an ultrasonic vibrator 18 as a vibration source, which apply ultrasonic vibrations to the metal powder 25. This removes the oxide film on the metal powder 25 without interfering with the electron beam irradiation. As a result, when the electron beam is irradiated onto the fabrication area 11, the insulation resistance from the electron beam irradiation area to the ground of the fabrication plate 19 is reduced, and electrical conduction is achieved, preventing the metal powder 25 from becoming charged. As a result, scattering of the metal powder 25 due to repulsive forces generated by charging the metal powder particles 25 is prevented.

[0024] Second Embodiment Fig. 3 is a diagram showing the configuration of a metal additive manufacturing apparatus 100 according to a second embodiment. Fig. 4 is an enlarged view showing the configuration of a powder processing apparatus 50 of the metal additive manufacturing apparatus 100 according to the second embodiment. Fig. 5 is a cross-sectional view showing the configuration of the powder processing apparatus 50 of the metal additive manufacturing apparatus 100 according to the second embodiment. Fig. 6 is another cross-sectional view showing the configuration of the powder processing apparatus 50 of the metal additive manufacturing apparatus 100 according to the second embodiment. Fig. 5 is a cross-sectional view taken along line V-V in Fig. 4. Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 4.

[0025] In the second embodiment, the powder passage 17, ultrasonic vibrator 18, and ultrasonic blade 27 of the first embodiment are replaced with a powder processing device 50. Other configurations of the second embodiment are the same as those of the first embodiment, and redundant description will be omitted. As shown in FIGS. 3 and 4 , the powder processing device 50 includes a casing 32 having a flow path 34 formed therein, an impeller 31 having blades 35, and an actuator 33 that applies a rotational force to the impeller 31. The flow path 34 has a flow path inlet 34a and a flow path outlet 34b. The powder processing device 50 functions as an oxide film removal unit that applies kinetic energy to the metal powder 25 to remove an oxide film on the surface of the metal powder 25.

[0026] The metal powder 25 flowing from the powder container 16 into the powder processing apparatus 50 collides with the blades 35 arranged on both the front and back sides of the rotating impeller 31, receives kinetic energy from the blades 35, and repeatedly moves back and forth between the flow passage 34 and the blades 35 in response to the rotation of the impeller 31. The metal powder 25 moves back and forth between the flow passage 34 and the blades 35 from the powder container 16 side of the casing 32 to the powder metering device 23 side of the casing 32, and is discharged from the hole on the powder metering device 23 side of the casing 32. The rotational motion of the metal powder 25 repeatedly moving back and forth between the blades 35 and the flow passage 34 causes repeated collisions and friction between the metal powder particles 25 in the flow passage 34, thereby removing any oxide film on the surface of the metal powder 25.

[0027] In the first embodiment, the oxide film on the metal powder 25 is removed by an external force caused by ultrasonic vibration, whereas in the second embodiment, the oxide film is removed by applying kinetic energy to the metal powder 25 by rotational motion. Note that the power source for the actuator 33 is not particularly specified as long as it generates rotational power, such as a general electric motor or an air motor that rotates a turbine using air pressure.

[0028] The structure of the blades 35 and the casing 32 will now be described in detail. The inside of the casing 32 is formed with a space 34c for accommodating the impeller 31 having the blades 35, as well as a flow path 34 having grooves 34d and 34e for transporting the metal powder 25. The grooves 34d and 34e are formed symmetrically on the front and back surfaces of the impeller 31. As shown in Figures 5 and 6, the grooves 34d and 34e have semicircular cross sections rotated approximately 300 degrees around the central axis of the casing 32. Semicircular grooves are formed 360 degrees on both the front and back surfaces of the disc-shaped impeller 31, and multiple V-shaped blades 35 are arranged radially around the central axis of the impeller 31 so as to be symmetrical on the front and back surfaces of the grooves.

[0029] The metal powder 25 is transported while rotating on two axes, namely, rotating about the central axis of the impeller 31 between the radially arranged blades 35 and rotating about circumferential axes within the semicircular grooves 34d, 34e of the casing 32 and the semicircular grooves of the impeller 31. That is, the metal powder 25 given kinetic energy by the blades 35 rotates along the grooves 34d, 34e and repeats rotational motion from the flow path inlet 34a to the flow path outlet 34b, rotating about two axes including the central axis of the impeller 31 and the circumferential axes of the grooves 34d, 34e, causing repeated collisions and friction between the metal powder particles 25.

[0030] In addition, spiral grooves (not shown) whose radius increases with each rotation are provided on both the front and back surfaces of the impeller 31. These spiral grooves are used to push out the metal powder 25 that has entered between the impeller 31 and the casing 32 into the flow path 34 by centrifugal force.

[0031] Generally, the particle size of the metal powder 25 used in metal additive manufacturing is approximately 20 μm to 110 μm, so the gap 36 between the casing 32 and the impeller 31 only needs to be larger than the maximum particle size of the metal powder 25 used. In other words, the gap 36 between the blades 35 of the impeller 31 and the wall surface of the flow path 34 is larger than the maximum particle size of the metal powder 25, and is preferably 1.1 times or less the particle size of the metal powder 25.

[0032] Furthermore, the metal powder 25 used in metal additive manufacturing varies from relatively low-hardness metal materials such as copper and aluminum alloys to high-hardness metal materials such as titanium, Inconel (registered trademark), and stainless steel, and even special alloys such as aluminum nitride. Because collisions with these metal powders 25 can cause wear on the casing 32 and impeller 31, it is desirable to use materials of the same quality as the metal powder 25 to be manufactured in order to prevent contamination of the manufactured product.

[0033] In addition, if the collision and friction of the metal powder 25 in the powder processing device 50 is insufficient, multiple powder processing devices 50 can be connected in series and the oxide film removal process of the metal powder 25 can be performed using multiple powder processing devices 50.

[0034] As described above, according to the second embodiment, the impeller 31 having the blades 35 is disposed in the casing 32 having the annular flow path 34, and rotational kinetic energy is imparted to the metal powder 25, so that the oxide film on the metal powder 25 is removed without interfering with the electron beam irradiation. As a result, when the electron beam is irradiated onto the fabrication area 11, the insulation resistance from the electron beam irradiation area to the ground of the fabrication plate 19 is reduced, and electrical conduction is achieved, preventing the metal powder 25 from becoming charged. As a result, the scattering of the metal powder 25 due to the repulsive force generated by the charging of the metal powder particles 25 is prevented.

[0035] 7 is a diagram showing the configuration of a metal additive manufacturing apparatus 100 according to a third embodiment. In the third embodiment, an oxide film on the metal powder 25 is removed by ultrasonic vibrations in the squeegee 13. Other configurations in the third embodiment are the same as those in the first embodiment, and therefore, redundant explanations will be omitted.

[0036] As in the first embodiment, the squeegee 13 transports the metal powder 25 to the build region 11 and spreads it evenly across the powder bed 12 to a uniform thickness. A flow path 57 for the metal powder 25 is formed within the squeegee 13. The flow path 57 is surrounded by a stator 58 and a vibration part 67 that generates ultrasonic vibrations. The vibration part 67 also functions as a blade that spreads and spreads the metal powder 25 evenly. The metal powder 25 discharged from the powder container 16 passes through the powder metering device 23 and is then introduced into the squeegee 13. Inside the squeegee 13, the vibration part 67 applies vibrations to the metal powder 25, causing repeated collisions and friction between the stator 58 and the vibration part 67, thereby removing the oxide film on the surface of the metal powder 25. The vibration part 67 also functions as an oxide film removal unit that applies kinetic energy to the metal powder 25 to remove the oxide film on the surface of the metal powder 25.

[0037] According to the third embodiment, the oxide film on the surface of the metal powder 25 is removed by the vibrating part 67 in the squeegee 13, and the metal powder 25 spread evenly in the build region 11 is finely fluidized by the vibrations applied from the lower end of the vibrating part 67. As a result, finer metal powder 25 enters the gaps between overlapping particles of metal powder 25 in the deposit layer 28, resulting in a denser deposit layer 28, which ultimately contributes to improving the density of the shaped product after melting.

[0038] Fourth Embodiment Fig. 8 is a perspective view showing the configuration of a powder processing device 55 arranged in a metal additive manufacturing apparatus 100 according to a fourth embodiment. Fig. 9 is a cross-sectional view showing the configuration of a powder processing device 55 arranged in a metal additive manufacturing apparatus 100 according to the fourth embodiment. Fig. 10 is a longitudinal-sectional view showing the configuration of a powder processing device 55 arranged in a metal additive manufacturing apparatus 100 according to the fourth embodiment. In the fourth embodiment, the powder processing device 50 in the second embodiment is replaced with the powder processing device 55. Also, in the fourth embodiment, the powder measuring device 23 in the second embodiment is replaced with a powder measuring device (not shown) corresponding to the powder processing device 55. The other configurations in the fourth embodiment are the same as those in the second embodiment, and therefore, repeated explanations will be omitted.

[0039] The metal powder 25 stored in the powder container 16 is supplied to the powder processing device 55 serving as the oxide film removal unit. The powder processing device 55 includes a mortar-shaped stator 68 disposed on the upper side and a mortar-shaped rotor 69 disposed on the lower side. The contact surfaces of the stator 68 and the rotor 69 are made of a material with a lower elastic modulus than the metal powder 25. The contact surfaces of the stator 68 and the rotor 69 may be made of a material with a higher hardness than the metal powder 25, such as ceramics. A plurality of radially arranged grooves 71 are formed on the contact surface of the stator 68 or the rotor 69. The grooves 71 may also be formed on the stator 68 and the rotor 69. An inlet 73 for the metal powder 25 is formed near the center of rotation of the rotor 69 on the top of the stator 68. An outlet 72 for the metal powder 25 is formed on the circumferential side of the rotor 69. The outlet 72 may also be formed on the bottom surface of the rotor 69. The stator 68 may be disposed on the lower side, and the rotor 69 may be disposed on the upper side. The driving force of the rotor 69 may be any device capable of providing rotational power, such as a general electric motor, a pneumatic actuator, or an ultrasonic motor.

[0040] The radially extending grooves 71 are shaped as straight or curved lines extending from the center of rotation. The depth of the grooves 71 is greater than the minimum value of the particle size distribution of the metal powder 25 and less than the maximum value of the particle size distribution of the metal powder 25. The minimum value of the gap 70 between the stator 68 and the rotor 69 is set to be the upper limit value of the particle size distribution of the metal powder 25.

[0041] In the powder processing device 55, the metal powder 25 flows from the inlet 73 between the mortar-shaped stator 68 and rotor 69, and as it passes through the grooves 71 and is transferred from the center of rotation to the outer periphery, the metal powder particles 25 collide with each other, removing the oxide film on the surface of the metal powder 25. In addition, the metal powder 25 with a small particle size distribution comes into contact with and is absorbed by the metal powder 25 with a relatively large particle size, forming a single metal powder 25.

[0042] As described above, according to the fourth embodiment, the mortar-shaped stator 68 and the mortar-shaped rotor 69, which are provided with the radial grooves 71, impart kinetic energy to the metal powder 25, thereby removing the oxide film on the metal powder 25 without interfering with the electron beam irradiation. As a result, when the electron beam is irradiated onto the fabrication area 11, the insulation resistance from the electron beam irradiation area to the ground of the fabrication plate 19 is reduced, and electrical conduction is achieved, preventing the metal powder 25 from becoming charged. As a result, the scattering of the metal powder 25 due to the repulsive force generated by the charging of the metal powder particles 25 is prevented.

[0043] Fifth Embodiment Fig. 11 is a diagram showing the configuration of a metal additive manufacturing apparatus 100 according to a fifth embodiment. Fig. 12 is a perspective view showing the configuration of a powder processing apparatus 60 arranged in the metal additive manufacturing apparatus 100 according to the fifth embodiment. Fig. 13 is a plan view showing the configuration of a powder processing apparatus 60 arranged in the metal additive manufacturing apparatus 100 according to the fifth embodiment. Fig. 14 is a perspective view showing a certain rotation state of a rotor 62 in the powder processing apparatus 60 arranged in the metal additive manufacturing apparatus 100 according to the fifth embodiment. Fig. 15 is a perspective view showing another rotation state of the rotor 62 in the powder processing apparatus 60 arranged in the metal additive manufacturing apparatus 100 according to the fifth embodiment. Fig. 16 is a perspective view showing yet another rotation state of the rotor 62 in the powder processing apparatus 60 arranged in the metal additive manufacturing apparatus 100 according to the fifth embodiment. Fig. 17 is a perspective view showing the operation of the powder processing apparatus 60 arranged in the metal additive manufacturing apparatus 100 according to the fifth embodiment.

[0044] As shown in FIG. 11 , a powder processing device 60 serving as an oxide film removal unit is attached to the lower part of the powder container 16. The powder processing device 60 includes a mortar-shaped stator 61 disposed on the upper side and a mortar-shaped rotor 62 disposed on the lower side. The rotor 62 rotates relative to the stator 61 and reciprocates in the direction of the rotation axis. The stator 61 has an inlet 63 for the metal powder 25 on its upper surface. The stator 61 includes an inclined portion 61 a and a flat portion 61 b ​​on its lower surface. The flat portion 61 b ​​is disposed on the outer diameter side of the lower surface of the stator 61 and has a flat surface perpendicular to the rotation axis of the rotor 62. The inclined portion 61 a is disposed on the inner diameter side of the lower surface of the stator 61 and has an inclined surface inclined with respect to the rotation axis of the rotor 62.

[0045] The rotor 62 has an inclined portion 62a and a flat portion 62b on its upper surface. The flat portion 62b is located on the outer diameter side of the upper surface of the rotor 62 and has a flat surface perpendicular to the rotation axis of the rotor 62. The inclined portion 62a is located on the inner diameter side of the upper surface of the rotor 62 and has an inclined surface inclined with respect to the rotation axis of the rotor 62. The inclined portion 62a of the rotor 62 is provided with a passage 64, which is a groove for transporting the metal powder 25 supplied from the inlet 63 of the stator 61 to the flat portion 62b. The rotor 62 has an outlet 66 for discharging the metal powder 25. A passage for transporting the metal powder 25 supplied from the inlet 63 of the stator 61 may also be formed in the inclined portion 61a of the stator 61. Alternatively, a passage for transporting the metal powder 25 may be formed only in the stator 61.

[0046] FIG. 17 shows four different rotational positions of the rotor 62 as it rotates. The rotational motion of the rotor 62, indicated by arrow E1 in FIG. 17, is performed by a drive unit (not shown). The driving force of the rotor 62 may be any device capable of providing rotational power, such as a general electric motor, a pneumatic actuator, or an ultrasonic motor. The reciprocating motion of the rotor 62 is achieved by the rotational power of the drive unit, the inclined portions 61 a and 62 a, and a spring (not shown). The force in the direction of moving the rotor 62 away from the stator 61, indicated by arrow E2 in FIG. 17, is achieved by the rotational motion of the rotor 62 and the inclined portions 61 a and 62 a. The force in the direction of moving the rotor 62 toward the stator 61 is achieved by a spring disposed on the rotor 62 and connecting the rotor 62 to the stator 61.

[0047] In this powder processing apparatus 60, the metal powder 25 is transferred from the bottom of the powder container 16 through an inlet 63 on the top surface of the stator 61 and a passage 64 in the rotor 62 to the sliding surface (flat portions 61b, 62b) between the stator 61 and the rotor 62. The metal powder 25 is subjected to loads in the direction of rotation and the rotation axis on the sliding surface, and flows into the outlet 66 while rolling. The metal powder 25 returning from the entrance of the outlet 66 moves to the sliding surface between the stator 61 and the rotor 62. The oxide film on the surface of the metal powder 25 discharged from the outlet 66 has been removed by friction between the metal powder particles 25 themselves.

[0048] As described above, according to the fifth embodiment, the rotor 62 having the inclined portion 62a slides and rotates repeatedly against the stator 61 having the inclined portion 61a, causing the metal powder 25 to rub against and be crushed between the stator 61 and the rotor 62, thereby removing the oxide film on the surface of the metal powder 25. Therefore, the impedance of the metal powder 25 decreases, and powder processing before manufacturing becomes possible without causing charging or smoke even when irradiated with an electron beam when supplied to the manufacturing region 11.

[0049] In the fourth and fifth embodiments, friction is applied to the metal powder 25 by the mortar-shaped stators 68, 61 and the mortar-shaped rotors 69, 62, but other configurations may be adopted as long as the metal powder 25 is sandwiched between two members and the two members are moved relative to each other to apply friction to the metal powder 25 and remove the oxide film on the metal powder 25.

[0050] Sixth Embodiment Fig. 18 is a diagram showing the configuration of a metal additive manufacturing apparatus 100 according to a sixth embodiment. In the third embodiment, the blade that spreads the metal powder 25 and the vibration component 67 that applies ultrasonic vibrations to the metal powder 25 are integrated into the squeegee 13, but in the sixth embodiment, these are separate components. In the sixth embodiment, the oxide film on the metal powder 25 is removed by ultrasonic vibrations of an ultrasonic blade 80 that is arranged in parallel with the blade 82 of the squeegee 13. The other configurations of the sixth embodiment are the same as those of the first embodiment, and therefore, repeated explanations will be omitted.

[0051] As in the first embodiment, the blade 82 of the squeegee 13 carries the metal powder 25 to the build region 11 and spreads it evenly to a uniform thickness on the powder bed 12. The ultrasonic blade 80 serving as an oxide film removal unit is provided in parallel with the blade 82 and spreads the metal powder 25 evenly, similar to the blade 82. The ultrasonic blade 80 is connected to an ultrasonic vibrator 81 and vibrates ultrasonically due to the ultrasonic vibrations of the ultrasonic vibrator 81.

[0052] In the sixth embodiment, the blade 82 of the squeegee 13 and the ultrasonic blade 80 move over the build region 11 while pressing down on the metal powder 25, thereby forming the powder bed 12. The metal powder 25 supplied to the build region 11 is vibrated by the excitation force of the ultrasonic blade 80. This causes repeated collisions between the metal powder particles 25 or between the metal powder particles 25 and the powder bed 12 up to the previous layer, thereby removing the oxide film on the outermost surface. Removal of the oxide film reduces the impedance of the powder bed 12, and prevents charging and smoke from occurring even when irradiated with an electron beam.

[0053] As described above, according to the sixth embodiment, the ultrasonic blade 80 is provided in parallel with the squeegee 13, so that the oxide film on the metal powder 25 is removed without interfering with the irradiation of the electron beam.

[0054] Seventh Embodiment Fig. 19 is a cross-sectional view showing a conceptual configuration of a powder processing apparatus 90 arranged in a metal additive manufacturing apparatus 100 according to a seventh embodiment. In the fourth embodiment, the grooves 71 formed in at least one of the stator 68 and the rotor 69 are radial, and in the fifth embodiment, the passages 64 for transferring the metal powder 25 are formed in at least one of the stator 61 and the rotor 62, but these grooves 71 and passages 64 may also be spiral.

[0055] The powder processing device 90 includes a spiral stator 91 and a spiral rotor 92, and the rotor 92 orbits eccentrically with respect to the center of rotation. The powder processing device 90 has a so-called scroll compressor structure. A passage 95 between the stator 91 and the rotor 92 is arranged in a spiral shape from an inlet 93 at the center of rotation, and the radius of rotation increases as the passage 95 approaches an outlet 94 on the outer diameter side. As the rotor 92 rotates eccentrically with respect to the center of rotation, the width of the passage 95 gradually increases from the inlet 93 toward the outlet 94.

[0056] The minimum width of the passage 95 between the rotor 92 and the stator 91 is greater than the diameter of the metal powder 25. The rotor 92 and the stator 91 are made of an elastic body having a lower hardness than the metal powder 25.

[0057] As described above, according to the seventh embodiment, the groove through which the metal powder 25 is transferred is spiral-shaped, and the rotor 92 rotates eccentrically, so that the metal powder 25 is efficiently transferred through the passage 95 whose width gradually increases. As a result, the transferred metal powder 25 rubs against each other, removing the oxide film on the surface.

[0058] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, or embodiments may be combined with each other, and some of the configurations may be omitted or modified within the scope of the gist of the present disclosure.

[0059] 9 Powder supply table, 11 Building area, 12 Powder bed, 13 Squeegee, 14 Vacuum chamber, 15 Electron gun, 16 Powder container, 17 Powder passage, 18, 81 Ultrasonic vibrator, 19 Building plate, 20 Earth ground, 21 Vacuum pump, 22 Control device, 23 Powder metering device, 24 Lifting stage, 25 Metal powder, 26 Central axis, 27, 80 Ultrasonic blade, 28 Deposition layer, 29 Building object, 31 Impeller, 32 Casing, 33 Actuator, 34, 57 Flow path, 34a Flow path inlet, 34b Flow path outlet, 34c Space, 34d, 34e, 71 Groove, 35 Blade, 36 Gap, 40 Metal powder supply unit, 45 Building unit, 50, 55, 60, 90 Powder processing device, 58, 61, 68, 91 Stator, 61a, 62a Inclined portion, 61b, 62b Flat portion, 62, 69, 92 Rotor, 63, 73, 93 Inlet, 64, 95 Passage, 66, 72, 94 Outlet, 67 Vibration part, 70 Gap, 82 Blade, 100 Metal additive manufacturing device.

Claims

1. A metal additive manufacturing device comprising: a powder container for storing metal powder; a modeling plate that is placed in a modeling area where an electron beam is irradiated; and a squeegee that moves the metal powder supplied from the powder container to the modeling plate and spreads it evenly to form a powder bed, wherein the metal powder in the modeling area is irradiated with the electron beam to melt and solidify the metal powder, thereby forming a three-dimensional object, wherein an oxide film removal unit is provided in the flow path of the metal powder from the outlet of the powder container to the squeegee, which imparts kinetic energy to the metal powder to remove an oxide film on the surface of the metal powder.

2. The metal additive manufacturing device according to claim 1, characterized in that the oxide film removal unit comprises: a vibration source; and a vibration member arranged in the flow path for applying vibration energy of the vibration source to the metal powder passing through the flow path.

3. The metal additive manufacturing device according to claim 2, characterized in that the gap between the vibration member and the wall surface of the flow path is larger than the maximum particle size of the metal powder and is not more than 1.1 times the particle size of the metal powder.

4. The metal additive manufacturing device according to claim 1, characterized in that the oxide film removal unit is disposed in the flow path and comprises a rotating impeller having a plurality of blades, and imparts rotational kinetic energy from the plurality of blades to the metal powder passing through the flow path.

5. The metal additive manufacturing device according to claim 4, characterized in that the gap between the blade and the wall surface of the flow path is larger than the maximum particle size of the metal powder and is not more than 1.1 times the particle size of the metal powder.

6. The metal additive manufacturing apparatus according to claim 2, characterized in that the oxide film removing unit is disposed on the squeegee.

7. The metal additive manufacturing device according to claim 6, characterized in that the squeegee is an integrated unit of a blade for spreading the metal powder and the vibration member.

8. The metal additive manufacturing device according to claim 6, characterized in that the squeegee is a blade for spreading the metal powder evenly and the vibration member are separate bodies.

9. The metal additive manufacturing device of claim 1, characterized in that the oxide film removal unit comprises: a mortar-shaped stator; a rotating mortar-shaped rotor; and a groove formed in at least one of the stator and the rotor on the opposing surfaces of the stator and the rotor, and imparts kinetic energy to the metal powder from the powder container.

10. The metal additive manufacturing apparatus according to claim 9, characterized in that the grooves are arranged radially.

11. The metal additive manufacturing device according to claim 1, characterized in that the oxide film removal unit comprises: a mortar-shaped stator having an inclined surface; a mortar-shaped rotor having an inclined surface facing the inclined portion of the stator and rotating; a groove formed in at least one of the stator and the rotor on the facing surfaces of the stator and the rotor; and a spring connecting the stator and the rotor, and the metal powder from the powder container is crushed by rotating and reciprocating the rotor relative to the stator.

12. The metal additive manufacturing apparatus according to claim 9 or 11, characterized in that the grooves are arranged in a spiral shape, and the rotor rotates eccentrically.

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