Metal additive manufacturing apparatus and metal additive manufacturing method

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

Technical Field

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

Background Art

[0002] In metal additive manufacturing using an electron beam as a heat source, a metal powder is irradiated with an electron beam to form a metal object. Although the metal powder is originally a conductive material, it has a large specific surface area and an oxide film with a thickness of several tens of nanometers is formed on the surface. When an oxide film is formed on the metal powder, when the powder bed is formed, the metal powders do not contact each other, and the insulation resistance between the irradiation area of the electron beam and the ground arranged on the forming plate becomes high, resulting in a problem that conduction cannot be achieved.

[0003] In Patent Document 1, in order to prevent the charging of metal powder, a plasma source is installed in a vacuum chamber, and ions ionized contrary to the charging of the metal powder are radiated from the plasma source to electrically neutralize the powder bed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, since an electric circuit and an electrode serving as an ion source are installed near the orbit of the electron beam, there is a risk of interfering with the orbit of the electron beam during irradiation of the electron beam.

[0006] The present disclosure has been made in view of the above, and an object thereof is to obtain a metal additive manufacturing apparatus that removes an oxide film of metal powder without obstructing irradiation of an electron beam and enables ground conduction in an irradiation area of the electron beam.

Means for Solving the Problems

[0007] To solve the above-mentioned problems and achieve the objective, the metal additive manufacturing apparatus of this disclosure comprises a powder container for storing metal powder, a build plate positioned in a build area irradiated with an electron beam, and a squeegee that moves and spreads the metal powder supplied from the powder container to the build plate to form a powder bed. The metal additive manufacturing apparatus creates a three-dimensional object by irradiating the metal powder in the build area with an electron beam and melting and solidifying the metal powder. An oxide film removal section is provided in the flow path of the metal powder from the outlet of the powder container to the squeegee to apply kinetic energy to the metal powder and remove the oxide film on the surface of the metal powder. The oxide film removal section is arranged in the flow path and includes an impeller with multiple blades that rotates, transferring rotational kinetic energy from the multiple blades to the metal powder passing through the flow path. It is characterized by the following: [Effects of the Invention]

[0008] The metal additive manufacturing apparatus of this disclosure has the effect of removing the oxide film of metal powder without interfering with electron beam irradiation and enabling ground conductivity in the electron beam irradiation area. [Brief explanation of the drawing]

[0009] [Figure 1] Diagram showing the configuration of the metal additive manufacturing apparatus according to Embodiment 1. [Figure 2] This figure shows the configuration of the fabrication section of the metal additive manufacturing apparatus according to Embodiment 1. [Figure 3] This figure shows the configuration of the metal additive manufacturing apparatus according to Embodiment 2. [Figure 4] This figure shows an enlarged view of the powder processing apparatus configuration of the metal additive manufacturing apparatus according to Embodiment 2. [Figure 5] Cross-sectional view showing the configuration of the powder processing apparatus for the metal additive manufacturing apparatus according to Embodiment 2. [Figure 6] Another cross-sectional view showing the configuration of the powder processing apparatus for the metal additive manufacturing apparatus according to Embodiment 2. [Figure 7] This figure shows the configuration of the metal additive manufacturing apparatus according to Embodiment 3. [Figure 8] A perspective view showing the configuration of the powder processing apparatus arranged in the metal additive manufacturing apparatus according to Embodiment 4. [Figure 9] Cross-sectional view showing the configuration of the powder processing apparatus arranged in the metal laminated manufacturing apparatus according to Embodiment 4 [Figure 10] Longitudinal sectional view showing the configuration of the powder processing apparatus arranged in the metal laminated manufacturing apparatus according to Embodiment 4 [Figure 11] Diagram showing the configuration of the metal laminated manufacturing apparatus according to Embodiment 5 [Figure 12] Perspective view showing the configuration of the powder processing apparatus arranged in the metal laminated manufacturing apparatus according to Embodiment 5 [Figure 13] Plan view showing the configuration of the powder processing apparatus arranged in the metal laminated manufacturing apparatus according to Embodiment 5 [Figure 14] Perspective view showing a certain rotational state of the rotor in the powder processing apparatus arranged in the metal laminated manufacturing apparatus according to Embodiment 5 [Figure 15] Perspective view showing another rotational state of the rotor in the powder processing apparatus arranged in the metal laminated manufacturing apparatus according to Embodiment 5 [Figure 16] Perspective view showing yet another rotational state of the rotor in the powder processing apparatus arranged in the metal laminated manufacturing apparatus according to Embodiment 5 [Figure 17] Perspective view showing the operation of the powder processing apparatus arranged in the metal laminated manufacturing apparatus according to Embodiment 5 [Figure 18] Diagram showing the configuration of the metal laminated manufacturing apparatus according to Embodiment 6 [Figure 19] Cross-sectional view showing the conceptual configuration of the powder processing apparatus arranged in the metal laminated manufacturing apparatus according to Embodiment 7

Mode for Carrying Out the Invention

[0010] Hereinafter, the metal laminated manufacturing apparatus according to the embodiment will be described in detail based on the drawings.

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

[0012] In the metal additive manufacturing apparatus 100, after supplying the metal powder 25 to the shaping region 11, the metal powder 25 is spread evenly. In the metal additive manufacturing apparatus 100, the metal powder 25 is melted by irradiating an electron beam onto the metal powder 25, and then the melted metal powder 25 is solidified. The metal additive manufacturing apparatus 100 performs the shaping of a three-dimensional shaped object 29, which is a three-dimensional object in which the melted and solidified metal powder 25 is deposited, by repeating these operations.

[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 passage 17 is a flow path 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 the ultrasonic vibration 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 gives kinetic energy to the metal powder 25 and removes the oxide film on the surface of the metal powder 25.

[0014] Metal powder 25, weighed by the powder weighing device 23, is placed on the powder supply table 9. The squeegee 13 has a blade that carries the metal powder 25 from the powder supply table 9 to the molding area 11 and spreads it evenly across 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. The powder bed 12 is covered with metal powder 25. As shown in Figure 2, the powder bed 12 covers the entire perimeter (up, down, left, right, front, and back) of the build plate 19. The build area 11 is the 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 the 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 connection 20.

[0016] The electron gun 15 emits an electron beam. The vacuum pump 21 exhausts the gas inside the vacuum chamber 14 to the outside. The control device 22 controls each component 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 Embodiment 1 will be described. In the initial state, with the vacuum chamber 14 open to the atmosphere, the lifting stage 24, powder bed 12, and build plate 19 are in the positional relationship shown in Figure 1. Next, with metal powder 25 stored in the powder container 16, the vacuum chamber 14 is lowered from atmospheric pressure to 10°C. -3 The pressure is reduced to approximately Pa. Then, electrons accelerated to 60kV from the electron gun 15 are irradiated onto the build area 11. When electrons collide with the build plate 19, their kinetic energy is converted into thermal energy, and the temperature of the build 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 build plate 19 to each component in the vacuum chamber 14 by radiant heat transfer or thermal conduction, and the temperature rise of each component stops after a few minutes to several tens of minutes.

[0018] Next, the metal powder 25 stored in the powder container 16 passes through the powder passage 17, is weighed in a fixed amount by the powder weighing device 23, and then transported to the powder supply stand 9. As the metal powder 25 passes through the powder passage 17, the control device 22 activates the ultrasonic vibrator 18. When the ultrasonic vibrator 18 is activated, the ultrasonic blade 27 vibrates ultrasonically, applying ultrasonic vibrations to the metal powder 25 passing through the inside of the powder passage 17. As a result, the particles of the metal powder 25 repeatedly collide and rub against each other. Through these collisions and frictions between the particles of the metal powder 25, the oxide film distributed on the surface of the metal powder 25 with a thickness of several nanometers to several tens of nanometers is removed, and the surface of the metal powder 25 becomes exposed, revealing the material of the metal powder 25.

[0019] The gap between the wall 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 between 50 μm and 100 μm, the clearance should be 110 μm, and if the particle size of the metal powder 25 used is between 20 μm and 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 of the powder passage 17 be larger than the maximum particle size of the metal powder 25 and no more than 1.1 times the particle size of the metal powder 25. In practice, it is difficult to control the narrow gap of the powder passage 17, so 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 weighing device 23 to the powder supply stand 9 is moved towards the build area 11 by the squeegee 13, forming a uniform deposit layer 28 with a thickness of 20 μm to 100 μm on the build area 11, as shown in Figure 2. The thickness of the deposit layer 28 can be arbitrarily determined by the operator as one of the build conditions. The squeegee 13 moves back and forth within the range indicated by arrow K1 at a speed set by the operator. Next, the electron gun 15 is started by the control device 22, and an electron beam is irradiated from the electron gun 15. The area of ​​the deposit layer 28 in the build area 11 irradiated by the electron beam melts and solidifies, joining with the lower build object 29 to form the build object 29.

[0021] During the formation of the object 29, the electron gun 15 receives a command from the control device 22 and scans the electron beam within the build area 11. The pattern of the scanning electron beam is tomographic data obtained by placing the 3D CAD (Three Dimensional Computer Aided Design) data of the object to be built within the build area 11 and slicing it according to the thickness of the deposited layer 28. This method is the same as that of general powder bed fusion additive manufacturing.

[0022] When creating the next layer, the lifting stage 24 is lowered downwards, in the opposite direction to the layering direction K2, by the thickness of the deposited layer 28. After this, the aforementioned operation is performed to create the next layer. This operation is repeated for the number of layers to be built.

[0023] As described above, in Embodiment 1, an ultrasonic blade 27 as a vibrating member and an ultrasonic vibrator 18 as a vibration source are provided in the flow path of the metal powder 25 from the outlet of the powder container 16 to the squeegee 13, so that ultrasonic vibrations are applied to the metal powder 25, the oxide film on the metal powder 25 is removed without interfering with the irradiation of the electron beam. As a result, when the electron beam is irradiated onto the molding area 11, the insulation resistance from the electron beam irradiation area to the ground of the molding plate 19 is reduced, and conductivity is achieved, thereby preventing the metal powder 25 from becoming charged. As a result, the scattering phenomenon of the metal powder 25 caused by the repulsive force generated by the charging of the metal powder particles 25 together is prevented.

[0024] Embodiment 2. Figure 3 is a diagram showing the configuration of the metal additive manufacturing apparatus 100 according to Embodiment 2. Figure 4 is an enlarged view showing the configuration of the powder processing apparatus 50 of the metal additive manufacturing apparatus 100 according to Embodiment 2. Figure 5 is a cross-sectional view showing the configuration of the powder processing apparatus 50 of the metal additive manufacturing apparatus 100 according to Embodiment 2. Figure 6 is another cross-sectional view showing the configuration of the powder processing apparatus 50 of the metal additive manufacturing apparatus 100 according to Embodiment 2. Figure 5 is a cross-sectional view taken along the VV line in Figure 4. Figure 6 is a cross-sectional view taken along the VI-VI line in Figure 4.

[0025] In Embodiment 2, the powder passage 17, ultrasonic vibrator 18, and ultrasonic blade 27 in Embodiment 1 are replaced by a powder processing apparatus 50. The other configurations in Embodiment 2 are the same as in Embodiment 1, and redundant explanations are omitted. As shown in Figures 3 and 4, the powder processing apparatus 50 comprises a casing 32 with a flow path 34 formed therein, an impeller 31 having blades 35, and an actuator 33 that provides 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 apparatus 50 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.

[0026] The metal powder 25 that flows from the powder container 16 into the powder processing device 50 collides with the blades 35 positioned on both sides of the rotating impeller 31. The metal powder 25 receives kinetic energy from the blades 35 and repeatedly reciprocates between the flow path 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 path 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 repeated rotational motion of the metal powder 25 repeatedly reciprocating between the blades 35 and the flow path 34 causes the metal powder particles 25 within the flow path 34 to collide and rub against each other, thereby removing the oxide film on the surface of the metal powder 25.

[0027] In Embodiment 1, the oxide film on the metal powder 25 is removed by external force due to ultrasonic vibration, whereas in Embodiment 2, the oxide film is removed by imparting kinetic energy to the metal powder 25 through rotational motion. The power source for the actuator 33 is not specifically designated as long as it generates rotational power, such as a general electric motor or an air motor that rotates a turbine using pneumatics.

[0028] The structure of the blades 35 and the casing 32 will be described in detail. Inside the casing 32, in addition to a space 34c that houses the impeller 31 having the blades 35, a flow path 34 is formed with grooves 34d and 34e for transporting the metal powder 25. The grooves 34d and 34e are formed symmetrically, corresponding to the front and back surfaces of the impeller 31. As shown in Figures 5 and 6, the grooves 34d and 34e have a semicircular cross-section that is rotated approximately 300 degrees with respect to the central axis of the casing 32. Furthermore, 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 with respect to the central axis of the impeller 31 in a symmetrical arrangement on the front and back surfaces.

[0029] The metal powder 25 is transported by two-axis rotation: rotation around the central axis of the impeller 31 between multiple radially arranged blades 35, and rotation around the circumferential axis within the semicircular grooves 34d, 34e of the casing 32 and the semicircular grooves of the impeller 31. In other words, the metal powder 25, which has kinetic energy supplied by the blades 35, rotates along the grooves 34d, 34e, and repeatedly rotates around two axes, including the central axis of the impeller 31 and the circumferential axes of the grooves 34d, 34e, from the flow path inlet 34a to the flow path outlet 34b, while repeatedly colliding and rubbing against each other.

[0030] Furthermore, both the front and back surfaces of the impeller 31 are provided with helical grooves (not shown) whose radius increases with each rotation. These helical grooves are for pushing 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 metal powder 25 used in metal additive manufacturing is approximately 20 μm to 110 μm. Therefore, the gap 36 between the casing 32 and the impeller 31 should 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 should be larger than the maximum particle size of the metal powder 25, and preferably 1.1 times or less the particle size of the metal powder 25.

[0032] Furthermore, the metal powders 25 used in metal additive manufacturing range from relatively low-hardness metal materials such as copper and aluminum alloys to high-hardness metal materials such as titanium, Inconel®, and stainless steel, as well as special alloys such as aluminum nitride. Since the casing 32 and impeller 31 may wear down due to collisions with these metal powders 25, it is desirable to use materials of the same quality as the metal powders 25 being manufactured for the casing 32 and impeller 31 in order to prevent contamination of the manufactured product.

[0033] Furthermore, if the collision and friction of the metal powder 25 in the powder processing device 50 are 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 Embodiment 2, an impeller 31 having blades 35 is arranged in a casing 32 having an annular flow path 34, and rotational kinetic energy is given to the metal powder 25, so that the oxide film of the metal powder 25 is removed without interfering with the irradiation of the electron beam. As a result, when the electron beam is irradiated onto the molding area 11, the insulation resistance from the electron beam irradiation area to the ground of the molding plate 19 is reduced, and conductivity is achieved, thereby preventing the metal powder 25 from becoming charged. As a result, the scattering phenomenon of the metal powder 25 caused by the repulsive force generated by the charging of the metal powders 25 together is prevented.

[0035] Embodiment 3. Figure 7 shows the configuration of the metal additive manufacturing apparatus 100 according to Embodiment 3. In Embodiment 3, the oxide film of the metal powder 25 is removed by ultrasonic vibration within the squeegee 13. The other configurations in Embodiment 3 are the same as in Embodiment 1, and redundant explanations are omitted.

[0036] Similar to Embodiment 1, the squeegee 13 transports the metal powder 25 to the build area 11 and spreads the powder bed 12 to a uniform thickness. A channel 57 for the metal powder 25 is formed inside the squeegee 13. The channel 57 is surrounded by a stator 58 and a vibrating component 67 that vibrates ultrasonically. The vibrating component 67 also functions as a blade for spreading the metal powder 25. The metal powder 25 that comes out of the powder container 16 passes through the powder weighing device 23 and is then introduced into the squeegee 13. Inside the squeegee 13, the vibrating component 67 vibrates the metal powder 25, causing the metal powder 25 to repeatedly collide and rub against each other between the stator 58 and the vibrating component 67, thereby removing the oxide film on the surface of the metal powder 25. The vibrating component 67 also functions as an oxide film removal unit that imparts kinetic energy to the metal powder 25 to remove the oxide film on the surface of the metal powder 25.

[0037] According to Embodiment 3, the vibrating component 67 in the squeegee 13 removes the oxide film from the surface of the metal powder 25, and the vibrations applied from the lower end of the vibrating component 67 cause the metal powder 25 spread evenly in the molding area 11 to flow in minute amounts. As a result, finer metal powder 25 enters the gaps where the metal powder 25 in the deposited layer 28 overlaps, resulting in a denser deposited layer 28, which in turn contributes to improving the density of the molded product after melting.

[0038] Embodiment 4. Figure 8 is a perspective view showing the configuration of the powder processing device 55 arranged in the metal additive manufacturing apparatus 100 according to Embodiment 4. Figure 9 is a cross-sectional view showing the configuration of the powder processing device 55 arranged in the metal additive manufacturing apparatus 100 according to Embodiment 4. Figure 10 is a vertical cross-sectional view showing the configuration of the powder processing device 55 arranged in the metal additive manufacturing apparatus 100 according to Embodiment 4. In Embodiment 4, the powder processing device 50 in Embodiment 2 is replaced with the powder processing device 55. Also, in Embodiment 4, the powder metering device 23 in Embodiment 2 is replaced with a powder metering device (not shown) corresponding to the powder processing device 55. The other configurations in Embodiment 4 are the same as in Embodiment 2, and redundant explanations are omitted.

[0039] Metal powder 25 stored in a powder container 16 is supplied to the powder processing device 55, which serves as an oxide film removal unit. The powder processing device 55 comprises a die-shaped stator 68 positioned on the upper side and a die-shaped rotor 69 positioned on the lower side. Each contact surface of the stator 68 and rotor 69 is made of a material with a lower elastic modulus than the metal powder 25. The contact surfaces of the stator 68 and rotor 69 may also 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 provided on the contact surface of the stator 68 or rotor 69. The grooves 71 may be provided on both the stator 68 and rotor 69. An inlet 73 for the metal powder 25 is provided on the upper part of the stator 68, near the rotation center of the rotor 69. An outlet 72 for the metal powder 25 is provided on the circumferential side surface of the rotor 69. The outlet 72 may be provided on the bottom surface of the rotor 69. The stator 68 may be positioned on the lower side and the rotor 69 on the upper side. The rotor 69 can be driven by any device that can provide rotational power, such as a general electric motor, pneumatic actuator, or ultrasonic motor.

[0040] The shape of the radially extending grooves 71 consists of straight lines or curves 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 of the particle size distribution of the metal powder 25.

[0041] In the powder processing apparatus 55, the metal powder 25 flows from the inlet 73 between the die-shaped stator 68 and rotor 69, and as it passes through the groove 71, it is transported from the center of rotation to the outer circumference, during which time the oxide film on the surface of the metal powder 25 is removed by collisions with other metal powder 25 particles. In addition, metal powder 25 with a small particle size distribution comes into contact with and is absorbed by metal powder 25 with a relatively large particle size, becoming a single, unified metal powder 25.

[0042] As described above, according to Embodiment 4, kinetic energy is imparted to the metal powder 25 by the die-shaped stator 68 and die-shaped rotor 69, which are provided with radial grooves 71, so that the oxide film on the metal powder 25 is removed without interfering with the irradiation of the electron beam. As a result, when the electron beam is irradiated onto the molding area 11, the insulation resistance from the electron beam irradiation area to the ground of the molding plate 19 is reduced, and conductivity is achieved, thereby preventing the metal powder 25 from becoming charged. As a result, the scattering phenomenon of the metal powder 25 caused by the repulsive force generated by the charging of the metal powders 25 together is prevented.

[0043] Embodiment 5. Figure 11 is a diagram showing the configuration of the metal additive manufacturing apparatus 100 according to Embodiment 5. Figure 12 is a perspective view showing the configuration of the powder processing apparatus 60 arranged in the metal additive manufacturing apparatus 100 according to Embodiment 5. Figure 13 is a plan view showing the configuration of the powder processing apparatus 60 arranged in the metal additive manufacturing apparatus 100 according to Embodiment 5. Figure 14 is a perspective view showing a certain rotation state of the rotor 62 in the powder processing apparatus 60 arranged in the metal additive manufacturing apparatus 100 according to Embodiment 5. Figure 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 Embodiment 5. Figure 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 Embodiment 5. Figure 17 is a perspective view showing the operation of the powder processing apparatus 60 arranged in the metal additive manufacturing apparatus 100 according to Embodiment 5.

[0044] As shown in Figure 11, the powder processing apparatus 60, which serves as an oxide film removal unit, is attached to the lower part of the powder container 16. The powder processing apparatus 60 comprises a die-shaped stator 61 positioned on the upper side and a die-shaped rotor 62 positioned on the lower side. The rotor 62 performs rotational motion and reciprocating motion in the direction of the rotation axis relative to the stator 61. The stator 61 has an inlet 63 for metal powder 25 on its upper surface. The stator 61 has an inclined portion 61a and a flat portion 61b on its lower surface. The flat portion 61b is positioned 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 61a is positioned on the inner diameter side of the lower surface of the stator 61 and has an inclined surface that is 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 that is 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 transferring the metal powder 25 supplied from the inlet 63 of the stator 61 to the flat portion 62b. The rotor 62 has a discharge port 66 for discharging the metal powder 25. The inclined portion 61a of the stator 61 may also have a passage for transferring the metal powder 25 supplied from the inlet 63 of the stator 61. Alternatively, a passage for transferring the metal powder 25 may be formed only in the stator 61.

[0046] Figure 17 shows the rotor 62 at four different rotational positions as it rotates. The rotational motion of the rotor 62, indicated by arrow E1 in Figure 17, is driven by a drive unit (not shown). Any device that can provide rotational power can be used to drive the rotor 62, such as a general electric motor, pneumatic actuator, or ultrasonic motor. The reciprocating motion of the rotor 62 is realized by the rotational power of the drive unit, the inclined parts 61a and 62a, and springs (not shown). The force in the direction that moves the rotor 62 away from the stator 61, indicated by arrow E2 in Figure 17, is realized by the rotational motion of the rotor 62 and the inclined parts 61a and 62a. The force in the direction that moves the rotor 62 closer to the stator 61 is realized by springs positioned on the rotor 62 and connecting the rotor 62 and 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 the inlet 63 on the top surface of the stator 61 and the passage 64 of the rotor 62 to the sliding surface (flat sections 61b, 62b) between the stator 61 and the rotor 62. The metal powder 25 is subjected to rotational and axial loads on the sliding surface and flows into the discharge port 66 while rolling. The metal powder 25 that returns from the entrance of the discharge port 66 moves to the sliding surface between the stator 61 and the rotor 62. The metal powder 25 discharged from the discharge port 66 has its surface oxide film removed by friction between the metal powder particles 25.

[0048] Thus, according to Embodiment 5, as the rotor 62 having an inclined portion 62a slides and rotates against the stator 61 having an inclined portion 61a, the metal powder 25 rubs against the stator 61 and rotor 62, grinding and removing the oxide film on the surface of the metal powder 25. Therefore, the impedance of the metal powder 25 is reduced, making it possible to perform pre-molding powder treatment that does not cause charging or smoke even when irradiated with an electron beam when supplied to the molding area 11.

[0049] In embodiments 4 and 5, friction is applied to the metal powder 25 by the mortar-shaped stators 68 and 61 and the mortar-shaped rotors 69 and 62. However, other configurations may be adopted as long as friction is applied to the metal powder 25 by sandwiching the metal powder 25 between two members and causing the two members to move relative to each other, thereby removing the oxide film on the metal powder 25.

[0050] Embodiment 6. Figure 18 shows the configuration of the metal additive manufacturing apparatus 100 according to Embodiment 6. In Embodiment 3, the squeegee 13 integrates a blade for spreading the metal powder 25 and a vibrating component 67 for applying ultrasonic vibrations to the metal powder 25, but in Embodiment 6, these are separate components. In Embodiment 6, the oxide film on the metal powder 25 is removed by ultrasonic vibrations from an ultrasonic blade 80 arranged in parallel with the blade 82 of the squeegee 13. The other configurations in Embodiment 6 are the same as in Embodiment 1, and redundant explanations are omitted.

[0051] The blade 82 of the squeegee 13, as in Embodiment 1, carries the metal powder 25 to the molding area 11 and spreads the powder bed 12 to a uniform thickness. The ultrasonic blade 80, which serves as an oxide film removal unit, is positioned alongside the blade 82 and spreads the metal powder 25 in the same way as 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 Embodiment 6, the powder bed 12 is formed as the blade 82 and ultrasonic blade 80 of the squeegee 13 move over the build area 11 while pressing down on the metal powder 25. The metal powder 25 supplied to the build area 11 vibrates due to the excitation force of the ultrasonic blade 80. As a result, the outermost oxide film is removed by repeated collisions between the metal powder 25 particles themselves, or between the metal powder 25 and the powder bed 12 up to the previous layer. With the removal of the oxide film, the impedance of the powder bed 12 decreases, and it no longer generates charge or smoke even when irradiated with an electron beam.

[0053] As described above, according to Embodiment 6, since ultrasonic blades 80 are provided in parallel with the squeegee 13, the oxide film on the metal powder 25 is removed without interfering with the irradiation of the electron beam.

[0054] Embodiment 7. Figure 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 Embodiment 7. In Embodiment 4, the grooves 71 formed in at least one of the stator 68 and rotor 69 are radial, and in Embodiment 5, a passage 64 for transferring metal powder 25 is formed in at least one of the stator 61 and rotor 62, but these grooves 71 and passage 64 may be spiral-shaped.

[0055] The powder processing device 90 comprises a spiral-shaped stator 91 and a spiral-shaped rotor 92, the rotor 92 performing an eccentric rotational motion with respect to the center of rotation. The powder processing device 90 has the structure of a so-called scroll compressor. The passage 95 between the stator 91 and the rotor 92 is arranged in a spiral shape from the inlet 93 at the center of rotation, and the radius of rotation increases as it approaches the discharge port 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 expands from the inlet 93 to the discharge port 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 stator 91 are made of an elastic material with a hardness lower than that of the metal powder 25.

[0057] Thus, according to Embodiment 7, the groove shape through which the metal powder 25 is transported is spiral-shaped, and the rotor 92 rotates eccentrically, so that the metal powder 25 is efficiently transported through the passage 95, which gradually widens. As a result, the transported metal powders 25 rub against each other, removing the oxide film from their surfaces.

[0058] The configurations shown in the embodiments described above are merely examples of the content of this disclosure, and can be combined with other known technologies, combined with other embodiments, and some parts of the configuration can be omitted or modified without departing from the gist of this disclosure. [Explanation of Symbols]

[0059] 9 Powder supply stand, 11 Build area, 12 Powder bed, 13 Squeegee, 14 Vacuum chamber, 15 Electron gun, 16 Powder container, 17 Powder passage, 18, 81 Ultrasonic vibrator, 19 Build plate, 20 Grounding, 21 Vacuum pump, 22 Control device, 23 Powder weighing device, 24 Lifting stage, 25 Metal powder, 26 Central axis, 27, 80 Ultrasonic blade, 28 Deposition layer, 29 Builded 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 Build unit, 50, 55, 60, 90 Powder processing unit, 58, 61, 68, 91 Stator, 61a, 62a Inclined section, 61b, 62b Flat section, 62, 69, 92 Rotor, 63, 73, 93 Inlet, 64, 95 Passage, 66, 72, 94 Outlet, 67 Vibrating component, 70 Gap, 82 Blade, 100 Metal additive manufacturing apparatus.

Claims

1. A powder container for storing metal powder, A build plate is placed in the build area where the electron beam is irradiated, The system includes a squeegee for moving the metal powder supplied from the powder container to the molding plate and spreading it evenly to form a powder bed, A metal additive manufacturing apparatus for creating a three-dimensional object by irradiating the metal powder in the molding area with an electron beam to melt and solidify the metal powder, An oxide film removal section is provided in the flow path of the metal powder from the outlet of the powder container to the squeegee, which applies kinetic energy to the metal powder to remove the oxide film on the surface of the metal powder. The oxide film removal unit is, The system comprises an impeller having multiple blades and rotating, which is arranged in the aforementioned flow path. The rotational kinetic energy from the multiple blades is transferred to the metal powder passing through the channel. A metal additive manufacturing apparatus characterized by the following features.

2. The gap between the blade and the wall of the flow path is greater than the maximum particle size of the metal powder and less than or equal to 1.1 times the particle size of the metal powder. The metal additive manufacturing apparatus according to feature 1.

3. A powder container for storing metal powder, A build plate is placed in the build area where the electron beam is irradiated, The system includes a squeegee for moving the metal powder supplied from the powder container to the molding plate and spreading it evenly to form a powder bed, A metal additive manufacturing apparatus for creating a three-dimensional object by irradiating the metal powder in the molding area with an electron beam to melt and solidify the metal powder, An oxide film removal section is provided in the flow path of the metal powder from the outlet of the powder container to the squeegee, which applies kinetic energy to the metal powder to remove the oxide film on the surface of the metal powder. The oxide film removal unit is, A mortar-shaped stator, A rotating mortar-shaped rotor, The stator and the rotor have opposing surfaces, and a groove is formed in at least one of the stator and the rotor, Transferring kinetic energy to the metal powder from the powder container. A metal additive manufacturing apparatus characterized by the following features.

4. The grooves are arranged radially. The metal additive manufacturing apparatus according to feature 3.

5. The grooves are arranged in a spiral pattern, The rotor rotates eccentrically. The metal additive manufacturing apparatus according to feature 3.

6. A powder container for storing metal powder, A build plate is placed in the build area where the electron beam is irradiated, The system includes a squeegee for moving the metal powder supplied from the powder container to the molding plate and spreading it evenly to form a powder bed, A metal additive manufacturing apparatus for creating a three-dimensional object by irradiating the metal powder in the molding area with an electron beam to melt and solidify the metal powder, An oxide film removal section is provided in the flow path of the metal powder from the outlet of the powder container to the squeegee, which applies kinetic energy to the metal powder to remove the oxide film on the surface of the metal powder. The oxide film removal unit is, A mortar-shaped stator having an inclined surface, A rotating mortar-shaped rotor having an inclined surface opposite to the inclined portion of the stator, The rotor is provided with a spring that applies a force in the direction that moves it toward the stator, The metal powder from the powder container is ground by causing the rotor to rotate and reciprocate relative to the stator. A metal additive manufacturing apparatus characterized by the following features.

7. A metal additive manufacturing method for creating a three-dimensional object on a build plate placed in a build area irradiated with an electron beam, The process involves moving the metal powder supplied from a powder container for storing metal powder to the molding plate using a squeegee and spreading it evenly to form a powder bed, In the flow path of the metal powder from the outlet of the powder container to the squeegee, an oxide film removal step is performed to apply kinetic energy to the metal powder and remove the oxide film on the surface of the metal powder. The process includes irradiating the metal powder in the molding region with the electron beam to melt and solidify the metal powder, The oxide film removal step involves applying a force in a direction that brings a mortar-shaped stator and a rotating mortar-shaped rotor facing the stator closer together, thereby grinding the metal powder from the powder container. A metal additive manufacturing method characterized by the following:

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