Three dimensional laminating and shaping apparatus

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 device that builds a structure by stacking thin layers of powder material on a stage one by one. [Background technology]

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

[0003] In a conventional 3D additive manufacturing device, for example, a powder material is spread layer by layer on a base plate installed on the upper surface of a stage. Next, only the two-dimensional structural portion of the powder material spread on the base plate, which corresponds to one cross section of the object, is melted using a heating mechanism consisting of an electron beam or laser. The object is then formed by stacking layers of such powder material one by one in the height direction (Z direction) (see, for example, Patent Document 1). The technology described in Patent Document 1 also describes the provision of a detection unit for observing the printing surface of the object. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-138653 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with conventional 3D additive manufacturing devices, there was a risk that scattered powder material or evaporated material generated from the manufacturing surface would adhere to the detection unit or the components around the detection unit. Furthermore, conventional 3D additive manufacturing devices had the problem that the detection unit would become very hot due to thermal radiation generated during manufacturing. As a result, conventional 3D additive manufacturing devices had the problem that the detection unit could not perform accurate detection operations.

[0006] Taking the above problems into consideration, the object of the present invention is to provide a three-dimensional additive manufacturing device that can prevent powder material scattered on the detection section and evaporated substances generated from the manufacturing surface from adhering to the detection section. [Means for solving the problem]

[0007] In order to solve the above problems and achieve the object of the present invention, the 3D additive manufacturing apparatus of the present invention includes a modeling plate, a powder supplying device, an irradiation device, a detection unit, and a shielding member. The powder supplying device supplies powder material to the modeling plate to form a powder layer. The irradiation device irradiates the powder layer with a primary beam. The detection unit detects backscattered electrons generated when the primary beam irradiates the powder material. The shielding member covers the detection surface of the detection unit in an openable and closable manner. [Effects of the Invention]

[0008] According to the three-dimensional additive manufacturing device of the present invention, it is possible to prevent scattered powder material and evaporated substances generated from the manufacturing surface from adhering to the detection unit. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing a three-dimensional additive manufacturing apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing the position of a detection unit in the three-dimensional additive manufacturing device according to the first embodiment of the present invention. [Figure 3] FIG. 2 is a plan view showing a detection unit and a support bracket in the three-dimensional additive manufacturing apparatus according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a front view showing a mask cover and a lifting mechanism in the three-dimensional additive manufacturing apparatus according to the first embodiment of the present invention. [Figure 5] 5A to 5C are explanatory views showing the lifting and lowering operation of the mask cover and the detection operation of the detection unit in the three-dimensional additive manufacturing apparatus according to the first embodiment of the present invention. [Figure 6] 4 is an enlarged plan view of an area A shown in FIG. 3. FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along the vertical direction of FIG. 6. [Figure 8] 3 is a flowchart showing the operation procedure of the three-dimensional additive manufacturing apparatus according to the first embodiment of the present invention. [Figure 9] FIG. 10 is a schematic cross-sectional view showing a three-dimensional additive manufacturing apparatus according to a second embodiment of the present invention. [Figure 10] FIG. 10 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] FIG. 10 is a diagram showing a state in which a detection unit in a three-dimensional additive manufacturing apparatus according to a second embodiment of the present invention is opened. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of a three-dimensional additive manufacturing device according to the present invention will be described with reference to Figures 1 to 11. Note that common members in the figures are given the same reference numerals.

[0011] 1. First embodiment 1-1.Configuration of 3D additive manufacturing equipment First, a first embodiment of a three-dimensional additive manufacturing device according to an embodiment of the present invention (hereinafter referred to as "this example") will be described with reference to FIG. Fig. 1 is a schematic cross-sectional view showing a three-dimensional additive manufacturing apparatus according to this embodiment. In the following description, in order to clarify the shapes and positional relationships of the various components of the three-dimensional additive manufacturing apparatus, the left-right direction in Fig. 1 is referred to as the X direction, the depth direction in Fig. 1 as the Y direction, and the up-down direction in Fig. 1 as the Z direction. The X direction, Y direction, and Z direction are perpendicular to each other. Furthermore, the X direction and Y direction are parallel to the horizontal direction, and the Z direction is parallel to the vertical direction.

[0012] The three-dimensional additive manufacturing device 10 shown in FIG. 1 is a device that irradiates a powder material made of a metal powder such as titanium, aluminum, or iron with an electron beam to melt the powder material, and then stacks layers of the solidified powder material to form a three-dimensional object.

[0013] 1, the 3D additive manufacturing apparatus 10 includes a vacuum chamber 12, a beam irradiation device 14, a powder supply device 16, a modeling table 18, a modeling box 20, and a collection box 21. The 3D additive manufacturing apparatus 10 also includes a modeling 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. The 3D additive manufacturing apparatus 10 also includes a plurality of detectors 40 that detect reflected electrons, and a support bracket 41 that supports the detectors 40.

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

[0015] The beam irradiation device 14 is a device that irradiates the electron beam 15 onto the build surface 32a of the powder layer formed by the build plate 22 or the powder material 32. The build surface 32a corresponds to the upper surface of the powder layer. The state of the powder layer changes as the 3D additive manufacturing process progresses. Although not shown, the beam irradiation device 14 has an electron gun that generates the electron beam 15, a focusing lens that focuses the electron beam generated by the electron gun, and a deflection lens that deflects the electron beam 15 focused by the focusing lens. The focusing lens is configured using a focusing coil and focuses the electron beam 15 by the magnetic field generated by the focusing coil. The deflection lens is configured using a deflection coil and deflects the electron beam 15 by the magnetic field generated by the deflection coil.

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

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

[0018] The modeling table 18 is arranged horizontally inside the vacuum chamber 12. The modeling table 18 is arranged below the powder supply device 16. The center of the modeling table 18 is open. The shape of the opening of the modeling table 18 is circular in plan view or angular in plan view (for example, rectangular in plan view).

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

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

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

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

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

[0024] The radiation shield cover 28 is disposed between the build plate 22 and the beam irradiation device 14 in the Z direction. The radiation shield cover 28 is made of a metal such as stainless steel. The radiation shield cover 28 shields against radiant heat generated when the electron beam 15 is irradiated onto the powder material 32 by the beam irradiation device 14. When the electron beam 15 is irradiated onto the powder material 32 for sintering, the powder material 32 melts. However, if the heat radiated from the build surface 32a of the powder layer at this time, i.e., the radiant heat, is widely dispersed within the vacuum chamber 12, thermal efficiency deteriorates. In contrast, when the radiation shield cover 28 is disposed above the build plate 22, the heat radiated from the build surface 32a is shielded by the radiation shield cover 28, and the shielded heat is reflected by the radiation shield cover 28 and returned to the build plate 22. This allows for efficient use of the heat generated by the irradiation of the electron beam 15.

[0025] The radiation shield cover 28 also functions to prevent evaporated material generated when the powder material 32 is irradiated with the electron beam 15 from adhering (depositing) onto the inner wall of the vacuum chamber 12. When the powder material 32 is irradiated with the electron beam 15, part of the molten metal turns into mist-like evaporated material and rises from the building surface 32a. The radiation shield cover 28 is arranged to cover the space above the building surface 32a to prevent this evaporated material from diffusing inside the vacuum chamber 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 top surface of the powder material 32, i.e., the molded surface 32a. The opening 30a exposes the powder material 32 spread on the molded object 38, while the mask portion 30b shields the powder material 32 located outside the opening 30a. The shape of the opening 30a is set to match the shape of the molded object 22. For example, if the molded object 22 is circular in plan view, the opening 30a is set to be circular in plan view accordingly, and if the molded object 22 is rectangular in plan view, the opening 30a is set to be rectangular in plan view accordingly.

[0027] The mask cover 30 is disposed below the radiation shield cover 28. The opening 30a and mask portion 30b of the mask cover 30 are disposed between the build plate 22 and the radiation shield cover 28 in the Z direction. The mask cover 30 has an enclosure portion 30c that surrounds the periphery of the build surface 32a of the object 38. The enclosure portion 30c is disposed so as to surround the space above the opening 30a. A portion (upper portion) of the enclosure portion 30c overlaps with the radiation shield cover 28 in the Z direction. The enclosure portion 30c functions to shield radiant heat generated from the build surface 32a and to suppress the diffusion of evaporated substances 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 that protrudes toward the enclosure portion 30c of the mask cover 30 is formed on the inner wall surface of the radiation shield cover 28. This inner flange portion makes it possible to reduce 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 the scattered powder material 32 and evaporated substances generated from the building surface 32a from leaking out from above the mask cover 30 to the outside of the radiation shield cover 28.

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

[0030] The mask cover 30 is supported by a lifting mechanism 50 (see FIG. 4) so ​​as to be movable up and down in the Z direction, which is the vertical direction. The configuration of the lifting mechanism 50 and the lifting operation of the mask cover 30 will be described later.

[0031] A plurality of detectors 40 for detecting reflected electrons are disposed outside the enclosure 30c of the mask cover 30. The detectors 40 are supported by a support bracket 41. The support bracket 41 is disposed at the lower end of the radiation shield cover 28 in the Z direction. The support bracket 41 is disposed further outward than the lower end of the radiation shield cover 28 in the X and Y directions, i.e., in the horizontal direction. Therefore, the detectors 40 are disposed between the radiation shield cover 28 and the build surface 32a of the object 38 to be formed on the build plate 22. The support bracket 41 and the detectors 40 supported by the support bracket 41 are disposed 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 configurations of the detectors 40 and the support bracket 41 will be described later.

[0032] FIG. 2 is a plan view showing the position of the detection unit 40. As shown in FIG. As shown in FIG. 2 , the multiple detection units 40 are arranged to surround the periphery of the molded object 38. Here, a preliminary sintering region 39 in which the powder material 32 is preliminary sintered exists around the molded object 38. The multiple detection units 40 are arranged to surround the periphery of the molded object 38 and the preliminary sintering region 39, with the mask cover 30 sandwiched between them. In this way, by arranging the multiple detection units 40 near the lateral sides of the molded object 38, the state of the molded object 38 can be detected more accurately. The multiple detection units 40 detect backscattered electrons generated when the electron beam 15 is irradiated onto the molded object 38 and the preliminary sintering region 39.

[0033] Although an example in which a plurality of detecting units 40 are arranged has been described, the present invention is not limited to this, and the number of detecting units 40 may be one, three or less, or five or more.

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

[0035] FIG. 3 is a plan view showing the detector 40 and the support bracket 41. As shown in FIG. 3, the support bracket 41 has a support frame 41a and a fixing portion 41b. The support frame 41a has a substantially rectangular opening 41c. The shaped object 38, the preliminary sintering region 39, and the mask cover 30 are placed in the opening 41c of the support frame 41a. That is, the support frame 41a is placed so as to surround the periphery of the mask cover 30.

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

[0037] Furthermore, the support frame 41a is configured to be separable into multiple members. In particular, the member of the support frame 41a that is arranged on the front side of the vacuum chamber 12 can be separated from the other members. This prevents the support frame 41a from interfering with the object 38 when removing the object 38 from the vacuum chamber 12. As a result, the 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 insulator 43. Therefore, the detection surface of the detection unit 40 faces the shaped object 38 and the preliminary sintering region 39 in the horizontal direction. Furthermore, by providing the insulator 43 between the detection unit 40 and the support frame 41a, the detection unit 40 electrically insulates the support frame 41a. In other words, the detection unit 40 is fixed to the support frame 41a in a state where it is floating above the GND. Details of the fixed state between the detection unit 40 and the support bracket 41 will be described later.

[0039] Here, 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 is 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 become hot. In contrast, by fixing the support bracket 41 that supports the detection unit 40 to the vacuum chamber 12, the heat transferred to the detection unit 40 and the support bracket 41 is transferred to the vacuum chamber 12. This makes it possible to prevent the detection unit 40 and the support bracket 41 from becoming hot.

[0040] In this example, the support bracket 41 is fixed to the vacuum chamber 12, but the present invention is not limited to this. The support bracket 41 may be fixed to a member other than the vacuum chamber 12 that is away from the heat source. Therefore, the support bracket 41 may be fixed to the end of the modeling table 18.

[0041] Next, the mechanism for moving the mask cover 30 up and down and the detection operation of the detection unit 40 will be described in detail with reference to FIGS. 4 and 5. FIG. FIG. 4 is a front view showing the mask cover 30 and the lifting mechanism 50. As shown in FIG. 4, an elevating member 51 is disposed on the rear side of the vacuum chamber 12. The elevating member 51 is supported by the vacuum chamber 12 so as to be movable in the Z direction. The elevating member 51 is formed of a substantially flat plate-shaped member.

[0042] An inclined surface 51a and a horizontal surface 51b are formed at the lower end of the lifting member 51 in the Z direction. 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 in 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. 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 fixed bracket 54. The mask cover 30 moves up and down together with the lifting member 51 in the Z direction.

[0044] A cam follower 52 is provided at the upper end of the squeegee 16c in the Z direction. The cam follower 52 is provided 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 an inclined surface 51a and a 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 mask cover 30 shields the detection unit 40 from the build surface 32a. This prevents the 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. Furthermore, the mask cover 30 can shield the radiant heat generated from the build surface 32a, preventing the detection unit 40 from becoming too hot due to the influence of the radiant heat. As a result, it is possible to prevent the problem of being unable to properly acquire a backscattered electron signal from occurring.

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

[0047] Furthermore, the detection unit 40 is disposed further outward in the X and Y directions than the lower end of the radiation shield cover 28 in the Z direction and further outward than the printing surface 32a. Therefore, the radiation shield cover 28 can also protect the detection unit 40 from the effects of radiant heat transmitted thereto.

[0048] 5A to 5C are explanatory diagrams showing the lifting and lowering operation of the mask cover 30 and the detection operation of the detection unit 40. FIG. First, as shown in Fig. 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. As a result, 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 printing surface 32a.

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

[0050] Furthermore, when the detection unit 40 detects the reflected electrons 61, it is sufficient that there is a gap between the mask cover 30 and the printing surface 32a through which the reflected electrons 61 can pass. Therefore, as shown in Fig. 5B, when the detection unit 40 detects the reflected electrons 61, the squeegee 16c may be stopped before it reaches the horizontal surface 51b of the lifting member 51. This reduces the time required for the mask cover 30 to move up and down.

[0051] As shown in FIG. 5B , when the squeegee 16c is moved a predetermined distance to form a gap between the mask cover 30 and the build surface 32a through which the reflected electrons 61 can pass, i.e., when the detection unit 40 is positioned to view 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 a control command from the control unit to scan the electron beam 15 over the preliminary sintering region 39 on the build surface 32a and the build surface 32a of the object 38. At this time, the beam irradiation device 14 minimizes the electron beam current of the electron beam 15 and focuses the electron beam 15 on the build surface 32a. The detection unit 40 then detects the reflected electrons 61 generated by the electron beam 15.

[0052] When the detection unit 40 completes the detection of the reflected electrons 61, the squeegee 16c moves in the X direction and returns to its initial position as shown in FIG. 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 in the Z direction as shown in FIG. 5C. The periphery of the build surface 32a is then surrounded by the mask cover 30. Therefore, the mask cover 30 again shields the detection unit 40 from the build surface 32a. As a result, the scattered powder material 32 and evaporated substances generated from the build surface 32a can be prevented from adhering to the detection unit 40 and the insulator 43, and the detection unit 40 can be prevented from becoming too hot due to radiant heat.

[0053] Next, the fixed state between the detection unit 40 and the support bracket 41 will be described in detail with reference to FIGS. 6 is an explanatory diagram showing an enlarged view of an area A shown in FIG. 3, and FIG. 7 is a cross-sectional view taken along the vertical direction of FIG.

[0054] 6 and 7, the support frame 41a is formed of a hollow member. An insertion hole 41d is formed in the surface of the support frame 41a on which the detection unit 40 is attached. The shank of a fixing screw 45 is inserted into the insertion hole 41d. The head of the fixing screw 45 is disposed inside the support frame 41a. A first fixing plate 46 is provided on one end of the shank of the fixing screw 45, and a second fixing plate 47 is provided on the other end of the shank of the fixing screw 45, i.e., on 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 the insulator 43. The 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 backscattered electron signal T1 detected by the detection unit 40 passes through the fixing screw 45 and is transmitted to the signal line 44.

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

[0057] 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 greater than the lengths of the insulator 43 in the X and Z directions. That is, the outer diameter of the surface of the detection unit 40 that faces the surface 32a to be built is greater than the outer diameter of the insulator 43. Therefore, the surface of the insulator 43 that faces the surface 32a to be built is covered by the detection unit 40. In order for the scattered powder material 32 and the evaporated substances generated from the surface to adhere to the insulator 43, the powder material 32 and the evaporated substances must go around the detection unit 40.

[0058] In this way, it is possible to prevent the scattered powder material 32 and evaporated substances generated from the manufacturing surface 32a from adhering to the insulator 43. As a result, the insulating properties of the insulator 43 can be maintained, and it is possible to prevent the detection unit 40 from being electrically connected to GND. Furthermore, it is possible to prevent the insulator 43 from becoming too hot due to the powder material 32 or evaporated substances adhering to it, which would otherwise cause a decrease in the resistance value of the insulator 43. As a result, it is possible to prevent the problem of being unable to properly acquire a reflected electron signal from occurring.

[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 arranged so as to surround the periphery of the shaft of the fixing screw 45. This prevents the fixing screw 45 from coming into contact with the support frame 41a and causing electrical conduction.

[0060] 1-2. Example of operation of 3D additive manufacturing equipment Next, an example of the operation of the three-dimensional additive manufacturing device 10 having the above-described configuration will be described with reference to FIG. FIG. 8 is a flowchart showing an example of the operation of the three-dimensional additive manufacturing device 10.

[0061] 8, the beam irradiation device 14 operates based on a control command given by the control unit to heat the shaping plate 22 (step S1). In step S1, the beam irradiation device 14 operates under the control of the control unit to irradiate the shaping 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 an objective lens or the like provided in the beam irradiation device 14. This defocusing results in a state in which the focal position of the electron beam 15 is shifted downward from the top surface of the shaping plate 22, i.e., an underfocus state.

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

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

[0064] Next, the mask cover 30 is lifted (step S3). In step S3, as shown in Fig. 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 are lifted along the Z direction.

[0065] Next, the powder material 32 is spread all over the modeling plate 22 (step S4). In step S4, the powder supplying device 16 drops the powder material 32, which has been supplied from the hopper 16a to the powder dropper 16b, onto the modeling table 18 using the powder dropper 16b. Then, the powder supplying device 16 moves the squeegee 16c from one end to the other end in the X direction. This causes the powder material 32 to be spread all over the inner base 24. At this time, the powder material 32 is spread all over the modeling table 18 to a thickness equivalent to ΔZ. In addition, excess powder material 32 is collected in the collection box 21.

[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, thereby allowing 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 contact 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 shaping plate 22. At this time, the powder material 32 spread on the shaping plate 22 is exposed to the outside through the opening 30a of the mask cover 30. In addition, the powder material 32 present around the shaping plate 22 is covered by the mask portion 30b of the mask cover 30. The powder material 32 and the detection unit 40 are 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 an objective lens or the like provided in the beam irradiation device 14. This defocusing results in a state in which the focal position of the electron beam 15 is shifted downward 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 an area wider than the opening 30a of the mask cover 30. This results in pre-sintering not only of the powder material 32 exposed in the opening 30a, but also of the powder material 32 located outside the opening 30a (powder material 32 shielded by the mask portion 30b). Note that the electron beam 15 may be scanned over an area narrower than the opening area of ​​the opening 30a.

[0069] Thus, the process of covering the powder material 32 spread on the building plate 22 with a mask cover 30 having openings 30a and irradiating the powder material 32 with an electron beam 15 through the openings 30a to pre-sinter the powder material 32 corresponds to the first process. In this first process, the electron beam 15 is scanned over an area wider than the openings 30a of the mask cover 30, thereby pre-sintering at least all of the powder material 32 exposed to the openings 30a. Furthermore, pre-sintering the powder material 32 can impart conductivity to the powder material 32. This can suppress powder scattering during the sintering process that follows the pre-heating process.

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

[0071] During the processing of 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 too hot due to the influence of radiant heat.

[0072] Next, the mask cover 30 is lifted (step S8). In step S8, as shown in FIG. 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 are lifted along the Z direction. The height to which the mask cover 30 is lifted in step S8 may be lower than the height to which the mask cover 30 is lifted 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 a control command given from the control unit to scan the electron beam 15 over the pre-sintering region 39 where the pre-sintered powder material 32 exists and the molded object 38. At this time, the beam irradiation device 14 reduces the electron beam current of the electron beam 15 as much as possible and focuses the electron beam 15 onto the molded surface 32a. The detection unit 40 then detects the backscattered electrons 61 generated by the electron beam 15.

[0074] The detection unit 40 also outputs the detected backscattered electron signal to the control unit. The image processing unit of the control unit then performs arithmetic processing 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 contact 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 building plate 22. As a result, the detection unit 40 and the support bracket 41 are again shielded by the mask cover 30.

[0076] Next, in preparation for spreading the powder material 32, the build surface 32a is heated (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 an objective lens or the like provided in the beam irradiation device 14. This defocusing causes the focal position of the electron beam 15 to be shifted downward from the build surface 32a, i.e., an underfocus state.

[0077] The control unit also controls the beam irradiation device 14 to scan the electron beam 15 over an area wider than the opening 30a of the mask cover 30. As a result, the electron beam 15 is irradiated onto the entire surface 32a to be built that is exposed through the opening 30a. The surface 32a to be built is heated to a temperature sufficient to temporarily sinter the powder material 32. Once the surface 32a to be built has been heated to a predetermined temperature, the beam irradiation device 14 stops irradiating the electron beam 15.

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

[0079] Next, the mask cover 30 is lifted (step S13). In step S13, as shown in Fig. 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 are lifted along the Z direction.

[0080] Next, the powder material 32 is spread over the building plate 22 (step S14). In step S14, the powder supplying device 16 operates in the same manner as in step S4 above.

[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.

[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 above. 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 above. This completes the formation of the second layer.

[0083] Thereafter, the processes of steps S8 to S17 are repeated until the formation of the object 38 is completed in step S18. The formation of the object 38 is completed when the powder material 32 has been melted and solidified in the number of layers required to form the object 38. In this way, the desired object 38 is obtained.

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

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

[0086] The amount of lift of the mask cover 30 in step S8 may be less than the amount of lift of the mask cover 30 in step S3. That is, in the process of step S8, the mask cover 30 is lifted by an amount that allows the reflected electrons 61 to pass through the gap between the mask cover 30 and the printing surface 32a. This reduces the time required for the mask cover 30 to move up and down.

[0087] In this example, the lifting mechanism 50 is configured by providing the cam follower 52 on the squeegee 16c, and the lifting and lowering operation of the mask cover 30 and the movement of the squeegee 16c are linked, but the present invention is not limited to this. The lifting mechanism 50 that lifts and lowers the mask cover 30 may be provided separately from the movement mechanism that moves the squeegee 16c, and the lifting and lowering operation of the mask cover 30 and the movement of the squeegee 16c may be independent of each other.

[0088] 2. Second embodiment Next, a three-dimensional additive manufacturing apparatus according to a second embodiment will be described with reference to FIGS. Fig. 9 is a schematic diagram showing the configuration of a three-dimensional additive manufacturing apparatus according to the second embodiment, Fig. 10 and Fig. 11 are plan views showing a detection unit and a shielding member according to the second embodiment.

[0089] The three-dimensional additive manufacturing apparatus 10B according to the second embodiment differs from the three-dimensional additive manufacturing apparatus 10 according to the first embodiment in the configuration of the detection unit and the shielding member. Therefore, parts common to the three-dimensional additive manufacturing apparatus according to the first embodiment are designated by the same reference numerals and redundant explanations will be omitted.

[0090] 9, the 3D additive manufacturing apparatus 10B has multiple detectors 80 and a shutter mechanism 91 that represents a shielding member. The detectors 80 are disposed in the beam irradiation device 14 above the radiation shield cover 28 in the Z direction. The detectors 80 face the build plate 22 and the build surface 32a of the object 38. The shutter mechanism 91 is disposed below the detectors 80 in the Z direction.

[0091] 10 and 11, the plurality of detectors 80 are arranged in the X and Y directions around the optical axis of the electron beam 15 irradiated from the beam irradiation device 14. An opening through which the electron beam 15 passes is formed at the center of each of the detectors 80.

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

[0093] The shielding portion 92 also shields the radiant heat generated from the modeling surface 32a, thereby preventing the detection portion 80 from becoming too hot due to the influence of the radiant heat.

[0094] An operation unit 93 is provided on the outer edge of the shielding unit 92. A movable mechanism (not shown) is connected to the operation unit 93. By operating the operation unit 93 with the movable mechanism, the shielding unit 92 moves from a shielding state in which it shields the detection unit 80 shown in FIG. 10 to an open state in which it opens the detection unit 80 shown in FIG. 11. As shown in FIG. 11, when the shielding unit 92 moves away from the detection unit 80, the detection surface of the detection unit 80 faces the molded object 38 and the preliminary sintering region 39. As a result, the detection unit 80 detects reflected electrons generated when the electron beam 15 is irradiated onto the molded surface 32a.

[0095] The arrangement of the plurality of detecting 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 depending on the arrangement example of the plurality of detecting 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, and therefore a description thereof will be omitted. The 3D additive manufacturing apparatus 10B having such a configuration can also obtain the same actions and effects as those of the 3D additive manufacturing apparatus according to the first embodiment described above.

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

[0098] For example, in the above-described embodiment, an example has been described in which metal powder such as titanium, aluminum, or iron is used as the powder material, but the present invention is not limited thereto, and resin or the like may also be used as the powder material. Furthermore, an example has been described in which a beam irradiation device that irradiates an electron beam is used as the irradiation device, but the present invention is not limited thereto. For example, a laser irradiation device that irradiates a laser as a primary beam may also be used as the irradiation device.

[0099] Furthermore, some or all of the above-described components, functions, processing units, etc. may be implemented in hardware, for example, by designing an integrated circuit. Furthermore, the above-described components, functions, etc. may be implemented in software by a processor interpreting and executing a program that implements each function. Information such as the programs, tables, and files that implement each function can be stored in a storage device such as a memory, a hard disk, or an SSD (Solid State Drive), or in a storage medium such as an IC card, SD card, or DVD.

[0100] In this specification, the words "parallel" and "orthogonal" are used, but these do not mean only "parallel" and "orthogonal" in the strict sense, but also include "parallel" and "orthogonal" and may also mean a "substantially parallel" or "substantially orthogonal" state within a range in which the functions can be exerted. [Explanation of symbols]

[0101] 10, 10B...3D additive manufacturing device, 12...vacuum chamber, 12a...rear portion, 12b...connection portion, 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 portion, 32...powder material, 32a...building surface, 38...built object, 39...preliminary sintering area, 40, 80...detection portion, 41...support bracket, 41a...support frame, 41b...fixing portion, 41c...opening, 41d...insertion hole, 43...insulator, 44...signal line, 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 electrons, 80...detection unit, 91...shutter mechanism (shielding member), 92...shielding unit, 92a...opening, 93...operation unit, T1...backscattered electron signal

Claims

1. A shaping plate and a powder supplying device that supplies powder material to the build plate to form a powder layer; an irradiation device that irradiates the powder layer with a primary beam; a detection unit that detects backscattered electrons generated when the primary beam is irradiated onto the powder material; a shielding member that covers the detection surface of the detection unit in an openable and closable manner; A three-dimensional additive manufacturing device equipped with the above.

2. a support bracket for supporting the detection unit; a build table on which the build plate is placed; a vacuum chamber that accommodates the build plate, the build table, the powder supply device, the detection unit, the shielding member, and a 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 insulator is interposed between the support bracket and the detection unit. The three-dimensional additive manufacturing apparatus according to claim 2 .

4. a plurality of the detection units are arranged to surround the periphery of the object formed on the modeling plate, The shielding member has a surrounding portion that surrounds the periphery of the object formed on the forming plate, and is disposed between the detection unit and the object. The three-dimensional additive manufacturing device according to claim 1 .

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

6. the powder supplying device has a squeegee that spreads the powder material on the building plate by moving in a direction parallel to one surface of the building plate; The detection unit is disposed vertically above the squeegee. The three-dimensional additive manufacturing apparatus according to claim 5 .

7. A lifting mechanism is provided to move the shielding member up and down in the vertical direction. The three-dimensional additive manufacturing device according to any one of claims 4 to 6.

8. the powder supplying device has a squeegee that spreads the powder material on the building plate by moving in a direction parallel to one surface of the building plate; The lifting mechanism includes a cam follower provided on the squeegee; a lifting member to which the shielding member is fixed and with which the cam follower comes into contact, When the cam follower comes into contact with the lifting member, the lifting member is pushed up vertically together with the shielding member. The three-dimensional additive manufacturing apparatus according to claim 7.

9. a radiation shield cover disposed between the build plate and the irradiation device to shield against radiant heat; the powder supplying device has a squeegee that spreads the powder material on the building plate by moving in a direction parallel to one surface of the building plate; The detection unit is disposed horizontally outward of the lower end of the radiation shield cover, at a position facing the modeling surface, and vertically above the squeegee. The three-dimensional additive manufacturing apparatus according to claim 1 .

10. the detection unit is disposed above the building plate in a vertical direction and facing the object formed on the building plate, the shielding member has a shielding portion disposed between the detection unit and the build plate, The shielding portion is configured to move between a shielding state in which the shielding portion shields the detection surface of the detection portion and an open state in which the shielding portion 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 formed therein through which the primary beam can pass. The three-dimensional additive manufacturing apparatus according to claim 10.

Images