3D additive manufacturing device

Abstract

To provide a three dimensional lamination shaping apparatus capable of preventing a scattered powder material and an evaporated substance generated from a shaping surface from adhering to a detection part.SOLUTION: The three dimensional additive manufacturing device includes a shaping plate 22, a powder supply device 16, an irradiation device 14, a detection unit 40, and a shielding member 30. The powder supply device 16 supplies the powder material 32 to the shaping plate 22 to form a powder layer. The irradiation device 14 irradiates the powder layer with a primary beam 15. The detector 40 detects backscattered electrons generated when the powder material 32 is irradiated with the primary beam 15. The shielding member 30 openably and closably covers the detection surface of the detection unit 40.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a three-dimensional additive manufacturing apparatus that performs modeling by stacking thin layers of powder material one layer at a time on a stage.

Background Art

[0002] In recent years, three-dimensional additive manufacturing technology that performs modeling by stacking thin layers of powder material one layer at a time has been attracting attention, and many types of three-dimensional additive manufacturing technologies have been developed based on differences in the powder materials used and modeling methods.

[0003] As a modeling method for a conventional three-dimensional additive manufacturing apparatus, for example, a powder material is spread layer by layer on a base plate installed on the upper surface of a stage. Next, with respect to the powder material spread on the base plate, only the two-dimensional structural portion corresponding to one cross section of the modeled object is melted by a heating mechanism composed of an electron beam or a laser. Then, a modeled object is formed by stacking such layers of powder material one by one in the height direction (Z direction) (see, for example, Patent Document 1). Further, the technique described in Patent Document 1 describes that a detection unit for observing the modeling surface of the modeled object is provided.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, conventional 3D additive manufacturing systems had the problem of powder material scattered onto the detection unit and surrounding components, as well as evaporated substances generated from the fabricated surface, adhering to the detection unit. Furthermore, conventional 3D additive manufacturing systems had the problem of the detection unit becoming hot due to thermal radiation generated during fabrication. As a result, conventional 3D additive manufacturing systems had the problem of the detection unit being unable to perform accurate detection operations.

[0006] The object of the present invention is to provide a 3D additive manufacturing apparatus that can prevent scattered powder material and evaporated substances generated from the fabrication surface from adhering to the detection unit, taking into consideration the above-mentioned problems. [Means for solving the problem]

[0007] To solve the above problems and achieve the objectives of the present invention, the three-dimensional additive manufacturing apparatus of the present invention comprises a molding plate, a powder supply device, an irradiation device, a detection unit, and a shielding member. The powder supply device supplies powder material to the molding plate and forms a powder layer. The irradiation device irradiates the powder layer with a primary beam. The detection unit detects backscattered electrons generated when the primary beam irradiates the powder material. The shielding member covers the detection surface of the detection unit in a manner that can be opened and closed. [Effects of the Invention]

[0008] According to the 3D additive manufacturing apparatus of the present invention, it is possible to prevent scattered powder material and evaporated substances generated from the fabricated surface from adhering to the detection unit. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view illustrating a three-dimensional additive manufacturing apparatus according to a first embodiment of the present invention. [Figure 2] This is a plan view showing the position of the detection unit in a three-dimensional additive manufacturing apparatus according to a first embodiment of the present invention. [Figure 3] This is a plan view showing the detection unit and support bracket in a three-dimensional additive manufacturing apparatus according to a first embodiment of the present invention. [Figure 4] This is a front view showing the mask cover and lifting mechanism in a three-dimensional additive manufacturing apparatus according to a first embodiment of the present invention. [Figure 5] This is an explanatory diagram showing the raising and lowering operation of the mask cover and the detection operation of the detection unit in a three-dimensional additive manufacturing apparatus according to a first embodiment of the present invention. [Figure 6] This is a plan view showing an enlarged view of region A shown in Figure 3. [Figure 7] This is a cross-sectional view of Figure 6, taken by cutting it vertically. [Figure 8] This is a flowchart showing the operation procedure of a 3D additive manufacturing apparatus according to a first embodiment of the present invention. [Figure 9] This is a schematic cross-sectional view illustrating a three-dimensional additive manufacturing apparatus according to a second embodiment of the present invention. [Figure 10] This is a plan view showing a detection unit and a shielding member in a three-dimensional additive manufacturing apparatus according to a second embodiment of the present invention. [Figure 11] This figure shows the detection unit in a 3D additive manufacturing apparatus according to a second embodiment of the present invention in an open state. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the 3D additive manufacturing apparatus of the present invention will be described with reference to Figures 1 to 11. Note that common components in each figure are denoted by the same reference numerals.

[0011] 1. Example of the first embodiment 1-1. Configuration of a 3D additive manufacturing system First, a first embodiment of a three-dimensional additive manufacturing apparatus according to an embodiment of the present invention (hereinafter referred to as "this example") will be described with reference to Figure 1. FIG. 1 is a schematic cross-sectional view schematically showing the three-dimensional additive manufacturing apparatus of the present example. In the following description, to clarify the shape, positional relationship, and the like of each part of the three-dimensional additive manufacturing apparatus, the left-right direction in FIG. 1 is defined as the X direction, the depth direction in FIG. 1 is defined as the Y direction, and the up-down direction in FIG. 1 is defined as the Z direction. The X direction, Y direction, and Z direction are directions orthogonal to each other. The X direction and the Y direction are directions parallel to the horizontal direction, and the Z direction is a direction parallel to the vertical direction.

[0012] The three-dimensional additive manufacturing apparatus 10 shown in FIG. 1 is an apparatus that, for example, irradiates a powder material made of metal powder such as titanium, aluminum, or iron with an electron beam to melt the powder material, and stacks layers formed by solidifying the powder material to manufacture a three-dimensional object.

[0013] As shown in FIG. 1, the three-dimensional additive manufacturing apparatus 10 includes a vacuum chamber 12, a beam irradiation device 14, a powder supply device 16, a manufacturing table 18, a manufacturing box 20, and a collection box 21. The three-dimensional additive manufacturing apparatus 10 further includes a manufacturing plate 22, an inner base 24, a plate moving device 26, a radiation shield cover 28, and a mask cover 30 which is an example of a shielding member. Furthermore, the three-dimensional additive manufacturing apparatus 10 includes a plurality of detection units 40 that detect backscattered electrons, and a support bracket 41 that supports the detection units 40.

[0014] The vacuum chamber 12 is a chamber for creating a vacuum state by evacuating the air inside the chamber with a vacuum pump (not shown). The vacuum chamber 12 accommodates the powder supply device 16, the manufacturing table 18, the manufacturing box 20, the collection box 21, the manufacturing plate 22, the inner base 24, the plate moving device 26, the radiation shield cover 28, the mask cover 30, the detection units 40, and the support bracket 41.

[0015] The beam irradiation device 14 is a device that irradiates an electron beam 15 onto a shaping surface 32a of a powder layer formed by the shaping plate 22 or the powder material 32. The shaping surface 32a corresponds to the upper surface of the powder layer. The state of the powder layer changes as the three-dimensional additive manufacturing process progresses. Although not illustrated, the beam irradiation device 14 includes an electron gun that serves as a generation source of the electron beam 15, a focusing lens that focuses the electron beam generated by the electron gun, and a deflection lens that deflects the electron beam 15 focused by the focusing lens. The focusing lens is configured using a focusing coil, and focuses the electron beam 15 by a magnetic field generated by the focusing coil. The deflection lens is configured using a deflection coil, and deflects the electron beam 15 by a magnetic field generated by the deflection coil.

[0016] The powder supply device 16 is a device that supplies the powder material 32 onto the shaping plate 22 to form a powder layer, as an example of the powder material that is the raw material of the shaped object 38. The powder supply device 16 includes a hopper 16a, a powder dropper 16b, and a squeegee 16c. The hopper 16a is a container for storing metal powder. The powder dropper 16b is a device that drops the powder material 32 stored in the hopper 16a onto the shaping table 18. The squeegee 16c is an elongated member extending in the Y direction, and has a blade 16d (see FIG. 4) for spreading powder. The squeegee spreads the powder material 32 dropped by the powder dropper 16b over the shaping table 18.

[0017] The squeegee 16c is supported so as to be movable in the X direction by a moving mechanism (not illustrated). Then, the squeegee 16c moves in the X direction, which is a direction parallel to one surface of the shaping plate 22, so that the powder material 32 is spread over the entire surface of the shaping table 18.

[0018] The shaping table 18 is horizontally arranged inside the vacuum chamber 12. The shaping table 18 is disposed below the powder supply device 16. The central portion of the shaping table 18 is open. The opening shape of the shaping table 18 is a circular shape in plan view or a polygonal shape in plan view (for example, a quadrangular shape in plan view).

[0019] The build box 20 is a box that forms the space for builds. The upper end of the build box 20 is connected to the opening edge of the build table 18. The lower end of the build box 20 is connected to the bottom wall of the vacuum chamber 12.

[0020] The recovery box 21 is a box that recovers any excess powder material 32 supplied onto the build table 18 by the powder supply device 16.

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

[0022] The inner base 24 is provided to be movable in the vertical direction (Z direction). The build plate 22 moves vertically together with the inner base 24. The inner base 24 has larger external dimensions than the build plate 22. The inner base 24 slides vertically along the inner surface of the build box 20. A sealing member 36 is attached to the outer circumference of the inner base 24. The sealing member 36 is a member that maintains sliding properties and airtightness between the outer circumference of the inner base 24 and the inner surface of the build box 20. The sealing member 36 is made of a material that has heat resistance and elasticity.

[0023] The plate moving device 26 is a device that moves the build plate 22 and the inner base 24 in the vertical direction. The plate moving device 26 comprises a shaft 26a and a drive mechanism 26b. The shaft 26a is connected to the lower surface of the inner base 24. The drive mechanism 26b comprises a motor (not shown) and a power transmission mechanism, and by driving the power transmission mechanism with the motor as the drive source, the build plate 22 and the inner base 24 are moved vertically together with the shaft 26a. The power transmission mechanism is composed of, for example, a rack and pinion mechanism or a ball screw mechanism.

[0024] The radiation shield cover 28 is positioned in the Z direction between the build plate 22 and the beam irradiation device 14. The radiation shield cover 28 is made of a metal such as stainless steel. The radiation shield cover 28 shields against the radiant heat generated when the beam irradiation device 14 irradiates the powder material 32 with the electron beam 15. When the electron beam 15 is irradiated onto the powder material 32 to perform sintering, the powder material 32 melts. However, if the heat radiated from the build surface 32a of the powder layer, i.e., the radiant heat, is widely diffused into the vacuum chamber 12 at this time, the thermal efficiency will be poor. In contrast, when the radiation shield cover 28 is positioned above the build plate 22, the heat radiated from the build surface 32a is shielded by the radiation shield cover 28, and the shielded heat is reflected by the radiation shield cover 28 and returned to the build plate 22 side. Therefore, the heat generated by the irradiation of the electron beam 15 can be utilized efficiently.

[0025] Furthermore, the radiation shield cover 28 also serves to suppress the adhesion (deposition) of evaporated material generated when the powder material 32 is irradiated with the electron beam 15 to the inner wall of the vacuum chamber 12. When the powder material 32 is irradiated with the electron beam 15, some of the molten metal rises from the build surface 32a as a mist-like evaporated material. The radiation shield cover 28 is positioned to cover the space above the build surface 32a so that this evaporated material does not diffuse into the vacuum chamber 12.

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

[0027] The mask cover 30 is positioned below the radiation shield cover 28. The opening 30a and mask portion 30b of the mask cover 30 are positioned between the build plate 22 and the radiation shield cover 28 in the Z direction. The mask cover 30 has an enclosure portion 30c that surrounds the build surface 32a of the build object 38. The enclosure portion 30c is positioned to surround the space above the opening 30a. A portion (upper part) of the enclosure portion 30c overlaps with the radiation shield cover 28 in the Z direction. The enclosure portion 30c has the function of shielding from radiant heat generated from the build surface 32a and the function of suppressing the diffusion of evaporated material generated from the build surface 32a. In other words, the enclosure portion 30c performs the same function as the radiation shield cover 28.

[0028] Furthermore, an inner flange portion is formed on the inner wall surface of the radiation shield cover 28, projecting toward the enclosure portion 30c of the mask cover 30. This inner flange portion reduces the gap between the inner wall surface of the radiation shield cover 28 and the enclosure portion 30c of the mask cover 30. As a result, it is possible to prevent scattered powder material 32 and evaporated substances generated from the molded surface 32a from leaking out of the radiation shield cover 28 from above the mask cover 30.

[0029] The mask cover 30 is made of a metal with a higher melting point than the powder material 32 used as the raw material for the molded object 38. Furthermore, the mask cover 30 is made of a material with low reactivity with the powder material 32. For example, titanium can be used as a constituent material for the mask cover 30. Alternatively, the mask cover 30 may be made of the same metal material as the powder material 32 used. The mask cover 30 is electrically grounded to GND. During the preheating process before the main sintering process, described later, when the powder material 32 is pre-sintered by irradiation with the electron beam 15, the mask cover 30 acts as an electrical shield, thereby minimizing powder scattering.

[0030] Furthermore, the mask cover 30 is supported by a lifting mechanism 50 (see Figure 4) so ​​that it can move up and down in the vertical Z direction. The configuration of the lifting mechanism 50 and the lifting and lowering operation of the mask cover 30 will be described later.

[0031] Multiple detection units 40 for detecting backscattered electrons are arranged outside the enclosure portion 30c of the mask cover 30. The multiple detection units 40 are supported by a support bracket 41. The support bracket 41 is located at the lower end of the radiation shield cover 28 in the Z direction. The support bracket 41 is also located outside the lower end of the radiation shield cover 28 in the X and Y directions, i.e., the horizontal direction. Therefore, the multiple detection units 40 are positioned between the radiation shield cover 28 and the build surface 32a of the build object 38 formed on the build plate 22. In addition, the support bracket 41 and the detection units 40 supported by this support bracket 41 are located above the squeegee 16c in the Z direction. This prevents interference between the squeegee 16c and the support bracket 41 when the squeegee 16c moves in the X direction. The support bracket 41 is fixed to the vacuum chamber 12. The detailed configuration of the detection units 40 and the support bracket 41 will be described later.

[0032] Figure 2 is a plan view showing the position of the detection unit 40. As shown in Figure 2, the multiple detection units 40 are arranged to surround the fabricated object 38. Here, a pre-sintered region 39 exists around the fabricated object 38 where the powder material 32 has been pre-sintered. The multiple detection units 40 are arranged to surround the fabricated object 38 and the pre-sintered region 39, with the mask cover 30 in between. By arranging the multiple detection units 40 to the side of the fabricated object 38 and in its vicinity in this way, the state of the fabricated object 38 can be detected more accurately. The multiple detection units 40 then detect backscattered electrons generated when the electron beam 15 is irradiated onto the fabricated object 38 and the pre-sintered region 39.

[0033] Although an example with multiple detection units 40 has been described, the system is not limited to this. The number of detection units 40 may be one, three or fewer, or five or more.

[0034] The detection unit 40 is not limited to semiconductor detectors, but may also be a Ti electrode with a low secondary electron emission rate due to electron excitation. Alternatively, the detection unit 40 may detect reflected electrons incident on the electrode as a current using a current detection amplifier and detect its increase or decrease.

[0035] Figure 3 is a plan view showing the detection unit 40 and the support bracket 41. As shown in Figure 3, the support bracket 41 has a support frame 41a and a fixing part 41b. The support frame 41a has a substantially rectangular opening 41c. The molded object 38, the pre-sintering area 39, and the mask cover 30 are placed within the opening 41c of the support frame 41a. That is, the support frame 41a is positioned to surround the mask cover 30.

[0036] A fixing portion 41b is provided at one end of the support frame 41a in the Y direction, i.e., on the side facing the rear portion 12a of the vacuum chamber 12. The fixing portion 41b is fixed to the rear portion 12a of the vacuum chamber 12. In addition, a signal line 44 connected to the detection unit 40 is arranged within the support frame 41a and the fixing portion 41b of the support bracket 41. The signal line 44 is located inside the support bracket 41 and is connected from the fixing portion 41b to a connection portion 12b provided on the outside of the rear portion 12a of the vacuum chamber 12. As a result, the backscattered electron signal detected by the detection unit 40 is transmitted via the connection portion 12b to a control unit located on the outside of the vacuum chamber 12.

[0037] Furthermore, the support frame 41a is configured to be divisible into multiple components. In particular, the component of the support frame 41a positioned on the front side of the vacuum chamber 12 can be separated from the other components. This prevents the support frame 41a from interfering with the fabricated object 38 when removing the fabricated object 38 from the vacuum chamber 12. As a result, the fabricated object 38 can be easily removed from the vacuum chamber 12.

[0038] The detection unit 40 is fixed to the inside of the opening 41c in the support frame 41a via an insulating insulator 43. Therefore, the detection surface of the detection unit 40 faces the molded object 38 and the pre-sintered region 39 in the horizontal direction. Furthermore, by providing the insulating insulator 43 between the detection unit 40 and the support frame 41a, the detection unit 40 is electrically insulated from the support frame 41a. In other words, the detection unit 40 is fixed to the support frame 41a while floating from GND. Details of the fixing state between the detection unit 40 and the support bracket 41 will be described later.

[0039] In this case, if the support bracket 41 is fixed to the mask cover 30 or the radiation shield cover 28, which have a smaller heat capacity than the vacuum chamber 12, heat will be transferred from the mask cover 30 or the radiation shield cover 28 to the support bracket 41. As a result, the support bracket 41 and the detection unit 40 will become hot. In contrast, by fixing the support bracket 41 that supports the detection unit 40 to the vacuum chamber 12, the heat that would otherwise be transferred to the detection unit 40 or the support bracket 41 is transferred to the vacuum chamber 12. This prevents the detection unit 40 or the support bracket 41 from becoming hot.

[0040] In this example, the support bracket 41 is described as being fixed to the vacuum chamber 12, but this is not the only option. The support bracket 41 can be fixed to any component that is away from the heat source, other than the vacuum chamber 12. For example, the support bracket 41 may be fixed to the end of the build table 18.

[0041] Next, referring to Figures 4 and 5, the mechanism for raising and lowering the mask cover 30 and the details of the detection operation of the detection unit 40 will be explained. Figure 4 is a front view showing the mask cover 30 and the lifting mechanism 50. As shown in Figure 4, a lifting member 51 is positioned on the rear side of the vacuum chamber 12. The lifting member 51 is supported by the vacuum chamber 12 so as to be movable in the Z direction. The lifting member 51 is formed of a substantially flat plate-shaped member.

[0042] At the lower end of the lifting member 51 in the Z direction, an inclined surface 51a and a horizontal surface 51b are formed. The inclined surfaces 51a are formed at both ends of the lifting member 51 in the X direction. The horizontal surface 51b is formed between the two inclined surfaces 51a. The inclined surfaces 51a are continuously inclined toward the Z direction as they extend outward in the X direction from the horizontal surface 51b. The horizontal surface 51b is formed parallel to the X direction. Furthermore, the height of the horizontal surface 51b in the Z direction is set lower than that of the inclined surfaces 51a.

[0043] The mask cover 30 is fixed to the lifting member 51 via a fixing bracket 54. The mask cover 30 moves up and down in the Z direction together with the lifting member 51.

[0044] A cam follower 52 is provided at the upper end of the squeegee 16c in the Z direction. The cam follower 52 is located at one end of the squeegee 16c in the Y direction, i.e., on the back side of the vacuum chamber 12. When the squeegee 16c moves in the X direction, the cam follower 52 comes into contact with the inclined surface 51a and the horizontal surface 51b of the lifting member 51. The cam follower 52 and the lifting member 51 constitute a lifting mechanism 50 that moves the mask cover 30 up and down.

[0045] Furthermore, when the mask cover 30 is lowered, the space between the detection unit 40 and the build surface 32a is shielded by the mask cover 30. This prevents scattered powder material 32 and evaporated substances generated from the build surface 32a from adhering to the detection unit 40 or the insulator 43 supporting the detection unit 40. In addition, the mask cover 30 can shield against radiant heat generated from the build surface 32a, preventing the detection unit 40 from becoming overheated due to radiant heat. As a result, the problem of being unable to properly acquire the backscattered electron signal can be prevented.

[0046] Furthermore, the mask cover 30 prevents not only the detection unit 40 but also the insulator 43 from becoming hot due to radiant heat. As a result, the resistance value of the insulator 43 decreases when it becomes hot, preventing electrical contact between the detection unit 40 and the support bracket 41.

[0047] Furthermore, the detection unit 40 is positioned outside the molding surface 32a in the X and Y directions, while being positioned outside the lower end of the radiation shield cover 28 in the Z direction. Therefore, the radiation shield cover 28 can also protect the detection unit 40 from the effects of radiant heat.

[0048] Figures 5A to 5C are explanatory diagrams showing the raising and lowering operation of the mask cover 30 and the detection operation of the detection unit 40. First, as shown in Figure 5A, when the squeegee 16c moves in the X direction and approaches the mask cover 30, the cam follower 52 provided on the squeegee 16c comes into contact with the inclined surface 51a of the lifting member 51. As a result, the lifting member 51 is pushed upward in the Z direction by the cam follower 52. Consequently, the mask cover 30 moves upward in the Z direction together with the lifting member 51, and the mask cover 30 moves away from the molding surface 32a.

[0049] Furthermore, when the squeegee 16c reaches the horizontal surface 51b of the lifting member 51, a space is formed between the mask cover 30 and the molding surface 32a through which the squeegee 16c can pass. This allows the squeegee 16c to move along the X direction without interference between the squeegee 16c and the mask cover 30.

[0050] Furthermore, when the detection unit 40 detects the backscattered electrons 61, it is sufficient that there is a gap between the mask cover 30 and the molding surface 32a that allows the backscattered electrons 61 to pass through. Therefore, as shown in Figure 5B, when the detection unit 40 detects the backscattered electrons 61, the squeegee 16c may be stopped before it reaches the horizontal surface 51b of the lifting member 51. This makes it possible to shorten the time required for the lifting and lowering movement of the mask cover 30.

[0051] As shown in Figure 5B, when the squeegee 16c is moved to a predetermined distance, and a gap is formed between the mask cover 30 and the build surface 32a through which the backscattered electrons 61 can pass, that is, when the detection unit 40 is positioned to face the build surface 32a, the beam irradiation device 14 is controlled to irradiate the build surface 32a with the electron beam 15. At this time, the beam irradiation device 14 operates based on control commands from the control unit, scanning the electron beam 15 over the pre-sintered region 39 and the build surface 32a of the build object 38 on the build surface 32a. In this process, the beam irradiation device 14 reduces the electron beam current of the electron beam 15 as much as possible and focuses it on the build surface 32a for irradiation. The detection unit 40 then detects the backscattered electrons 61 generated by the electron beam 15.

[0052] Once the detection operation of the backscattered electrons 61 by the detection unit 40 is complete, the squeegee 16c moves in the X direction and returns to its initial position as shown in Figure 5C. As the squeegee 16c returns to its initial position, the cam follower 52 moves away from the inclined surface 51a of the lifting member 51. As a result, the lifting member 51 and the mask cover 30 descend along the Z direction, as shown in Figure 5C. The area around the build surface 32a is then surrounded by the mask cover 30. Therefore, the space between the detection unit 40 and the build surface 32a is again shielded by the mask cover 30. As a result, it is possible to prevent scattered powder material 32 and evaporated substances generated from the build surface 32a from adhering to the detection unit 40 and the insulator 43, and to prevent the detection unit 40 from becoming hot due to the effects of radiant heat.

[0053] Next, with reference to Figures 6 and 7, the details of the fixing state between the detection unit 40 and the support bracket 41 will be described. Figure 6 is an enlarged explanatory diagram showing area A as shown in Figure 3, and Figure 7 is a cross-sectional view obtained by cutting Figure 6 vertically.

[0054] As shown in Figures 6 and 7, the support frame 41a is formed from a hollow member. An insertion hole 41d is formed on the surface of the support frame 41a to which the detection unit 40 is attached. The shaft of the fixing screw 45 is inserted through the insertion hole 41d. The head of the fixing screw 45 is positioned inside the support frame 41a. A first fixing plate 46 is provided at one end of the shaft of the fixing screw 45, and a second fixing plate 47 is provided at the other end of the shaft of the fixing screw 45, i.e., the head side.

[0055] The detection unit 40 is fixed to the first fixing plate 46. The detection unit 40 is sandwiched between the first fixing plate 46 and an insulating insulator 43. The insulating insulator 43 is interposed between the detection unit 40 and the support frame 41a. A signal line 44 is connected to the fixing screw 45. Therefore, the reflected electron signal T1 detected by the detection unit 40 is transmitted to the signal line 44 by passing through the fixing screw 45.

[0056] Furthermore, an insulating insulator 43 is interposed between the second fixing plate 47 and the support frame 41a. This prevents the fixing screw 45 from coming into contact with the support frame 41a and prevents electrical conductivity between the fixing screw 45 and the support frame 41a. As a result, the detection unit 40 can be reliably electrically isolated from the support frame 41a.

[0057] Furthermore, as shown in Figures 6 and 7, the detection unit 40 is formed in a flat plate shape. The lengths of the detection unit 40 in the X and Z directions are larger than the lengths of the insulator 43 in the X and Z directions. That is, the outer diameter of the molding surface of the detection unit 40 that faces the molding surface 32a is set to be larger than the outer diameter of the insulator 43. Therefore, the surface of the insulator 43 that faces the molding surface 32a is covered by the detection unit 40. In order for the scattered powder material 32 and evaporated substances generated from the molding surface to adhere to the insulator 43, the powder material 32 and evaporated substances need to go around the detection unit 40.

[0058] In this way, it is possible to prevent powder material 32 scattered on the insulator 43 and evaporated substances generated from the molded surface 32a from adhering to it. As a result, the insulating properties of the insulator 43 can be maintained, and the detection unit 40 can be prevented from becoming conductive with GND. Furthermore, it is possible to prevent the insulator 43 from becoming hot due to the powder material 32 and evaporated substances to which it adheres, which would lower the resistance value of the insulator 43. As a result, it is possible to prevent the problem of not being able to properly acquire the backscattered electron signal.

[0059] Furthermore, an insulating member 48 is interposed between the shaft of the fixing screw 45 and the support frame 41a, the detection unit 40, the insulator 43, and the second fixing plate 47. The insulating member 48 is inserted into an insertion hole 41d provided in the support frame 41a and is positioned to surround the shaft of the fixing screw 45. This prevents the fixing screw 45 from contacting the support frame 41a and causing electrical contact.

[0060] 1-2. Examples of operation of a 3D additive manufacturing device Next, an example of the operation of the 3D additive manufacturing apparatus 10 having the above-described configuration will be explained with reference to Figure 8. Figure 8 is a flowchart showing an example of the operation of the 3D additive manufacturing apparatus 10.

[0061] As shown in Figure 8, the beam irradiation device 14 heats the build plate 22 by operating based on control commands provided by the control unit (step S1). In step S1, the beam irradiation device 14 operates under the control of the control unit and irradiates the build plate 22 with an electron beam 15 through the opening 30a of the mask cover 30. At this time, the control unit defocuses the electron beam 15 using the objective lens or the like provided by the beam irradiation device 14. This defocusing is a state in which the focus position of the electron beam 15 is shifted below the upper surface of the build plate 22, i.e., an underfocus state.

[0062] Furthermore, the control unit controls the beam irradiation device 14 to scan the electron beam 15 over a wider area than the opening 30a of the mask cover 30. As a result, the build plate 22 is heated by the irradiation of the electron beam 15. The build plate 22 is also heated to a temperature at which the powder material 32 is partially sintered. Once the build plate 22 has been heated to a predetermined temperature, the beam irradiation device 14 stops the irradiation of the electron beam 15. Scanning the electron beam 15 over a wider area than the opening 30a of the mask cover 30 means scanning the electron beam 15 over an area wider than the aperture area of ​​the opening 30a so that the opening 30a is contained within the scanning range (scanning area) of the electron beam 15. Alternatively, the electron beam 15 may be scanned over an area narrower than the aperture area of ​​the opening 30a.

[0063] Next, the build plate 22 is lowered by a predetermined amount (step S2). In step S2, the plate moving device 26 lowers the inner base 24 by a predetermined amount so that the upper surface of the build plate 22 is slightly lower than the upper surface of the powder material 32 spread on the build table 18. At this time, the build plate 22 is lowered by a predetermined amount together with the inner base 24. The predetermined amount described here (hereinafter also referred to as "ΔZ") corresponds to the thickness of one layer when the build object 38 is built by layering.

[0064] Next, the mask cover 30 is raised (step S3). In step S3, as shown in Figure 5A, the squeegee 16c is moved in the X direction to bring the cam follower 52 into contact with the inclined surface 51a of the lifting member 51. As a result, the lifting member 51 and the mask cover 30 rise along the Z direction.

[0065] Next, the powder material 32 is spread onto the build plate 22 (step S4). In step S4, the powder supply device 16 drops the powder material 32, which has been supplied from the hopper 16a to the powder dispenser 16b, onto the build table 18 using the powder dispenser 16b. Then, the powder supply device 16 moves the squeegee 16c from one end to the other in the X direction. This spreads the powder material 32 onto the inner base 24. At this time, the powder material 32 is spread on the build table 18 to a thickness equivalent to ΔZ. Any excess powder material 32 is collected in the recovery box 21.

[0066] Furthermore, when the squeegee 16c reaches the horizontal surface 51b of the lifting member 51, the mask cover 30 and the lifting member 51 rise to a height where they do not come into contact with the squeegee 16c. This allows the powder material 32 to be spread smoothly.

[0067] Next, the mask cover 30 is lowered (step S5). In step S5, the squeegee 16c is moved to a position where the cam follower 52 of the squeegee 16c does not come into contact with the inclined surface 51a and the horizontal surface 51b of the lifting member 51. As a result, the mask cover 30 and the lifting member 51 are lowered to the upper surface of the build plate 22. At this time, the powder material 32 spread on the build plate 22 is exposed to the outside through the opening 30a of the mask cover 30. Also, the powder material 32 surrounding the build plate 22 is covered by the mask portion 30b of the mask cover 30. The space between the powder material 32 and the detection unit 40 is shielded by the mask cover 30.

[0068] Next, the powder material 32 is pre-sintered (step S6). In step S6, the beam irradiation device 14 operates under the control of the control unit to irradiate the powder material 32 on the build plate 22 with the electron beam 15 through the opening 30a of the mask cover 30. At this time, the control unit defocuses the electron beam 15 using the objective lens or the like provided by the beam irradiation device 14. This defocusing is a state in which the focus position of the electron beam 15 is shifted below the upper surface (build surface 32a) of the powder material 32, i.e., an underfocus state. The control unit also controls the beam irradiation device 14 to scan the electron beam 15 over a wider area than the opening 30a of the mask cover 30. As a result, not only the powder material 32 exposed to the opening 30a, but also the powder material 32 located outside the opening 30a (the powder material 32 shielded by the mask part 30b) is pre-sintered. Note that the electron beam 15 may be scanned over an area smaller than the aperture area of ​​the opening 30a.

[0069] Thus, the first step involves covering the powder material 32 spread on the molding plate 22 with a mask cover 30 having an opening 30a, and then irradiating the powder material 32 with an electron beam 15 through the opening 30a to pre-sinter the powder material 32. In this first step, by scanning the electron beam 15 over a wider area than the opening 30a of the mask cover 30, at least all of the powder material 32 exposed to the opening 30a can be pre-sintered. Furthermore, pre-sintering the powder material 32 makes it conductive. Therefore, powder scattering in the main sintering step, which is performed after the preheating step, can be suppressed.

[0070] Next, the powder material 32 is melted and solidified (step S7). In step S7, the powder material 32, which has been pre-sintered as described above, is melted and solidified by irradiation with the electron beam 15, thereby performing full sintering on the powder material 32 as a pre-sintered body. This step corresponds to the second step. In the second step, the beam irradiation device 14 scans the electron beam based on two-dimensional data obtained by slicing the three-dimensional CAD (Computer-Aided Design) data of the target object to a certain thickness, thereby selectively melting the powder material 32 on the build plate 22. The powder material 32 melted by the irradiation of the electron beam solidifies after the electron beam has passed through. This completes the formation of the first layer. The second step corresponds to a selective melting step, as it selectively melts and solidifies the powder material 32 spread on the build plate 22 by scanning with the electron beam 15.

[0071] During the processing in steps S6 and S7, the detection unit 40 and the support bracket 41 are shielded by the mask cover 30. This prevents the scattered powder material 32 and evaporated substances from adhering to the detection unit 40 and the insulator 43, and also prevents the detection unit 40 from becoming overheated due to radiant heat.

[0072] Next, the mask cover 30 is raised (step S8). In step S8, as shown in Figure 5A, the squeegee 16c is moved in the X direction to bring the cam follower 52 into contact with the inclined surface 51a of the lifting member 51. As a result, the lifting member 51 and the mask cover 30 rise along the Z direction. The height to which the mask cover 30 rises in step S8 may be lower than the height to which the mask cover 30 rises in step S described above.

[0073] Next, a backscattered electron image is acquired (step S9). In step S9, the beam irradiation device 14 first operates based on control commands provided by the control unit to scan the electron beam 15 over the pre-sintered region 39 and the fabricated object 38 where the pre-sintered powder material 32 is present. At this time, the beam irradiation device 14 reduces the electron beam current of the electron beam 15 as much as possible and focuses it on the fabricated surface 32a for irradiation. The detection unit 40 then detects the backscattered electrons 61 generated by the electron beam 15.

[0074] Furthermore, the detection unit 40 outputs the detected backscattered electron signal to the control unit. The image processing unit of the control unit then performs calculations on the backscattered electron signal (backscattered electron information) acquired from the detection unit 40 to acquire a backscattered electron image (BSE image). The image processing unit also stores the acquired BSE image in the storage unit.

[0075] Next, the mask cover 30 is lowered (step S10). In step S10, the squeegee 16c is moved to a position where the cam follower 52 of the squeegee 16c does not come into contact with the inclined surface 51a and the horizontal surface 51b of the lifting member 51. As a result, the mask cover 30 and the lifting member 51 are lowered to the upper surface of the molding plate 22. Consequently, the detection unit 40 and the support bracket 41 are shielded again by the mask cover 30.

[0076] Next, the build surface 32a is heated in preparation for spreading the powder material 32 (step S11). In step S11, the beam irradiation device 14 operates under the control of the control unit to irradiate the build surface 32a with the electron beam 15 through the opening 30a of the mask cover 30. At this time, the control unit defocuses the electron beam 15 using the objective lens or the like provided by the beam irradiation device 14. This defocusing is a state in which the focus position of the electron beam 15 is shifted below the build surface 32a, i.e., an underfocus state.

[0077] Furthermore, the control unit controls the beam irradiation device 14 to scan the electron beam 15 over a wider area than the opening 30a of the mask cover 30. This ensures that the electron beam 15 irradiates the entire surface of the build surface 32a exposed to the opening 30a. The build surface 32a is also heated to a temperature sufficient to partially sinter the powder material 32. Once the build surface 32a has reached the predetermined temperature, the beam irradiation device 14 stops irradiating the electron beam 15.

[0078] Next, the build plate 22 is lowered by a predetermined amount (ΔZ) (step S12). In step S12, the plate moving device 26 lowers the inner base 24 by ΔZ so that the build surface 32a is slightly lower than the upper surface of the powder material 32 spread on the build table 18.

[0079] Next, the mask cover 30 is raised (step S13). In step S13, as shown in Figure 5A, the squeegee 16c is moved in the X direction to bring the cam follower 52 into contact with the inclined surface 51a of the lifting member 51. As a result, the lifting member 51 and the mask cover 30 rise along the Z direction.

[0080] Next, the powder material 32 is spread onto the molding plate 22 (step S14). In step S14, the powder supply device 16 operates in the same manner as in step S4.

[0081] Next, the mask cover 30 is lowered (step S15). In step S15, the squeegee 16c operates in the same manner as in step S5 above.

[0082] Next, the powder material 32 is pre-sintered (step S16). This step corresponds to the first step. In step S16, the beam irradiation device 14 operates in the same manner as in step S6. Then, the powder material 32 is melted and solidified (step S17). This step corresponds to the second step. In step S17, the beam irradiation device 14 operates in the same manner as in step S7. This completes the fabrication of the second layer.

[0083] From this point onward, steps S8 to S17 are repeated until the fabrication of the object 38 is completed in step S18. The fabrication of the object 38 is completed when the powder material 32 has melted and solidified to the number of layers required for the fabrication of the object 38. This results in the acquisition of the desired object 38.

[0084] In the above example, the operation to acquire the BSE image was performed after the main sintering process in step S7, but the timing of the operation to acquire the BSE image is not limited to this. For example, the operation to acquire the BSE image may be performed after the processing in step S11. In the operation to acquire the BSE image, the mask cover 30 is raised as shown in the processing in steps S8 and S13.

[0085] Furthermore, the raising and lowering of the mask cover 30 is performed when the detection unit 40 detects backscattered electrons. Therefore, the raising and lowering of the mask cover 30 is not limited to the example shown in Figure 8 above, and the mask cover 30 may also be raised during the process of melting the powder material 32 to detect backscattered electrons with the detection unit 40. The raising and lowering of the mask cover 30 and the detection operation by the detection unit 40 are set appropriately according to the requirements of the user using the 3D additive manufacturing apparatus 10.

[0086] Furthermore, the amount the mask cover 30 rises in step S8 may be lower than the amount the mask cover 30 rises in step S3. That is, in the process of step S8, the mask cover 30 is raised by the amount of gap that allows the reflected electrons 61 to pass between the mask cover 30 and the molding surface 32a. This makes it possible to shorten the time required for the raising and lowering movement of the mask cover 30.

[0087] In this example, a cam follower 52 is provided on the squeegee 16c as the lifting mechanism 50, and an example is described in which the lifting operation of the mask cover 30 and the movement operation of the squeegee 16c are linked. However, this is not the only example. The lifting mechanism 50 for raising and lowering the mask cover 30 may be provided separately from the movement mechanism for moving the squeegee 16c, and the lifting operation of the mask cover 30 and the movement operation of the squeegee 16c may be made independent of each other.

[0088] 2. Second Embodiment Example Next, a 3D additive manufacturing apparatus according to a second embodiment will be described with reference to Figures 9 to 11. Figure 9 is a schematic diagram showing a three-dimensional additive manufacturing apparatus according to a second embodiment. Figures 10 and 11 are plan views showing a detection unit and a shielding member according to a second embodiment.

[0089] The difference between the 3D additive manufacturing apparatus 10B according to the second embodiment and the 3D additive manufacturing apparatus 10 according to the first embodiment lies in the configuration of the detection unit and the shielding member. Therefore, here, parts common to the 3D additive manufacturing apparatus according to the first embodiment are denoted by the same reference numerals, and redundant explanations are omitted.

[0090] As shown in Figure 9, the 3D additive manufacturing apparatus 10B has a plurality of detection units 80 and a shutter mechanism 91 that indicates a shielding member. The detection units 80 are positioned on the beam irradiation device 14 above the radiation shield cover 28 in the Z direction. The detection units 80 face the molding plate 22 and the molding surface 32a of the molded object 38. The shutter mechanism 91 is positioned below the detection units 80 in the Z direction.

[0091] As shown in Figures 10 and 11, the multiple detection units 80 are arranged around the optical axis of the electron beam 15 irradiated from the beam irradiation device 14 in the X and Y directions. An aperture is formed at the center of the multiple detection units 80 through which the electron beam 15 passes.

[0092] The shutter mechanism 91 includes a shielding section 92 that shields the detection surfaces of the multiple detection sections 80, and an operating section 93. The shielding section 92 is formed in the shape of a substantially circular flat plate. An opening 92a is formed at the radial center of the shielding section 92 through which the electron beam 15 passes. The shielding section 92 prevents scattered powder material 32 and evaporated substances generated from the molded surface 32a from adhering to the detection section 80.

[0093] Furthermore, the shielding portion 92 shields against radiant heat generated from the molding surface 32a. This prevents the detection portion 80 from becoming overheated due to the effects of radiant heat.

[0094] An operating section 93 is provided on the outer edge of the shielding section 92. A movable mechanism (not shown) is connected to the operating section 93. By operating the operating section 93 with the movable mechanism, the shielding section 92 moves from a shielded state, which shields the detection section 80 as shown in Figure 10, to an open state, which exposes the detection section 80 as shown in Figure 11. As shown in Figure 11, when the shielding section 92 moves away from the detection section 80, the detection surface of the detection section 80 faces the fabricated object 38 and the pre-sintered region 39. As a result, the detection section 80 detects backscattered electrons generated when the electron beam 15 is irradiated onto the fabricated surface 32a.

[0095] Furthermore, the arrangement of multiple detection units 80 is not limited to the example shown in 10, and various other arrangement examples may be applied. The shape of the shielding unit 92 is set appropriately according to the arrangement example of the multiple detection units 80.

[0096] The other configurations are the same as those of the 3D additive manufacturing apparatus 10 according to the first embodiment described above, so their description will be omitted. The 3D additive manufacturing apparatus 10B having such a configuration can also obtain the same operations and effects as the 3D additive manufacturing apparatus according to the first embodiment described above.

[0097] It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the spirit of the invention as described in the claims.

[0098] For example, in the above-described embodiment, examples were given in which metal powders such as titanium, aluminum, and iron were used as the powder material, but the invention is not limited to this, and resins or the like may be used as the powder material. Also, in the example given in which a beam irradiation device that irradiates with an electron beam was used as the irradiation device, the invention is not limited to this. As the irradiation device, for example, a laser irradiation device that irradiates with a laser as the primary beam may be used.

[0099] Furthermore, some or all of the above-mentioned components, functions, and processing units may be implemented in hardware, for example, by designing an integrated circuit. Alternatively, the above-mentioned components and functions may be implemented in software by having the processor interpret and execute programs that realize each function. Information such as programs, tables, and files that realize each function can be stored in memory, hard disks, SSDs (Solid State Drives), or other recording media such as IC cards, SD cards, and DVDs.

[0100] In this specification, although terms such as "parallel" and "orthogonal" are used, these do not mean only strictly "parallel" and "orthogonal," but may also refer to states that are "approximately parallel" or "approximately orthogonal," which include "parallel" and "orthogonal" and are within a range in which they can perform their functions. [Explanation of symbols]

[0101] 10, 10B...3D additive manufacturing device, 12...Vacuum chamber, 12a...Rear section, 12b...Connection section, 14...Beam irradiation device (irradiation device), 15...Electron beam (primary beam), 16...Powder supply device, 16c...Squeegee, 16d...Blade, 18...Building table, 20...Building box, 21...Recovery box, 22...Building plate, 24...Inner base, 26...Plate moving device, 28...Radiation shield cover, 30...Mask cover (shielding member), 30c...Enclosure section, 32...Powder material, 32a...Building surface, 38...Building object, 39...Pre-sintering area, 40, 80...Detection section, 41...Support bracket, 41a...Support frame, 41b...Fixing section, 41c...Opening, 41d...Through hole, 43...Insulator, 44...Signal wire, 45...Fixing screw, 46...First fixing plate, 47...Second fixing plate, 50...Lifting mechanism, 51...Lifting member, 51a...Inclined surface, 51b...Horizontal surface, 52...Cam follower, 54...Fixing bracket, 61...Backscattered electron, 80...Detection unit, 91...Shutter mechanism (shielding member), 92...Shielding unit, 92a...Opening, 93...Operation unit, T1...Backscattered electron signal

Claims

1. A molding plate and A powder supply device that supplies powder material to the molding plate and forms a powder layer, An irradiation device for irradiating the powder layer with a primary beam, A detection unit for detecting backscattered electrons generated when the primary line irradiates the powder material, A shielding member that can open and close to cover the detection surface of the detection unit, A 3D additive manufacturing device equipped with [specific features / features].

2. A support bracket that supports the detection unit, A build table on which the aforementioned build plate is placed, The system comprises the molding plate, the molding table, the powder supply device, the detection unit, the shielding member, and a vacuum chamber housing the support bracket, The support bracket is fixed to the vacuum chamber or the build table. The three-dimensional additive manufacturing apparatus according to claim 1.

3. An insulating insulator is interposed between the support bracket and the detection unit. The three-dimensional additive manufacturing apparatus according to claim 2.

4. Multiple detection units are arranged so as to surround the object formed on the molding plate. The shielding member has a surrounding portion that encloses the molded object formed on the molding plate, and is positioned between the detection unit and the molded object. A three-dimensional additive manufacturing apparatus according to any one of claims 1 to 3.

5. The shielding member has at least an opening and a mask portion, and the opening exposes the powder material spread on the molding plate, while the mask portion shields the powder material located outside the opening. The three-dimensional additive manufacturing apparatus according to claim 4.

6. The powder supply device has a squeegee that moves in a direction parallel to one surface of the molding plate to spread the powder material onto the molding plate. The detection unit is positioned vertically above the squeegee. The three-dimensional additive manufacturing apparatus according to claim 5.

7. The shielding member is provided with a lifting mechanism for moving it up and down in the vertical direction. The three-dimensional additive manufacturing apparatus according to claim 4.

8. The powder supply device has a squeegee that moves in a direction parallel to one surface of the molding plate to spread the powder material onto the molding plate. The lifting mechanism includes a cam follower provided on the squeegee, The shielding member is fixed to a lifting member that the cam follower contacts, The lifting member is pushed upward vertically together with the shielding member when the cam follower comes into contact with it. The three-dimensional additive manufacturing apparatus according to claim 7.

9. The system further includes a radiation shield cover positioned between the molding plate and the irradiation device to shield against radiant heat, The powder supply device has a squeegee that moves in a direction parallel to one surface of the molding plate to spread the powder material onto the molding plate. The detection unit is positioned horizontally outside the lower end of the radiation shield cover, facing the molding surface, and vertically above the squeegee. The three-dimensional additive manufacturing apparatus according to claim 1.

10. The detection unit is positioned above the molding plate in the vertical direction, facing the molded object formed on the molding plate. The shielding member has a shielding portion that is positioned between the detection unit and the molding plate. The shielding portion moves between a shielded state, which shields the detection surface of the detection portion, and an open state, which exposes the detection surface of the detection portion. The three-dimensional additive manufacturing apparatus according to claim 1.

11. The shielding portion has an opening through which the primary line can pass. The three-dimensional additive manufacturing apparatus according to claim 10.

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