Three-dimensional molding apparatus

Abstract

To provide a three-dimensional molding apparatus capable of improving the molding accuracy of a molded article by correcting the irradiation position deviation of an electron beam due to the influence of a peripheral magnetic field.SOLUTION: A three-dimensional molding apparatus 100 performs molding of a three-dimensional molded article C by irradiating powder A for molding with an electron beam B to melt and solidify the powder A for molding over a plurality of layers. The three-dimensional molding apparatus 100 includes: an electron beam emission unit 2 for irradiating the powder A for molding with the electron beam B; a camera 51 for imaging an irradiation region of the electron beam B; and a control unit 5 for imaging the irradiation region including an irradiation reference point 38 by the camera 51 after irradiating the irradiation reference point 38 with the electron beam B, calculating a position of an actual irradiation point of the electron beam B based on the captured image, and correcting an irradiation position of the electron beam B when molding the three-dimensional molded article C in each layer based on the deviation between the calculated position of the actual irradiation point and the position of the irradiation reference point 38.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a three-dimensional modeling apparatus using an electron beam. [Background technology]

[0002] There is known a three-dimensional modeling apparatus that produces a three-dimensional object by stacking multiple layers of selectively solidified modeling powder by irradiating the modeling powder with an electron beam. During modeling, the electron beam is irradiated to a predetermined position of the laid modeling powder to melt and solidify the modeling powder to form a desired object. Modeling using an electron beam is easily affected by the magnetic field environment around the modeling apparatus, and measures are required to prevent deviation of the electron beam irradiation position due to the influence of the surrounding magnetic field.

[0003] In Patent Document 1, in order to prevent distortion in a direction perpendicular to the height direction of the object caused by the modeling stage descending obliquely rather than vertically, modeling is performed without correcting the irradiation position in advance, the amount of distortion of the object is measured and stored at multiple points of different heights, and the positional deviation is corrected based on the stored amount of distortion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-123761 A Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, no measures are taken against deviation of the irradiation position of the electron beam due to the influence of the surrounding magnetic field.

[0006] The present disclosure has been made in consideration of the above, and aims to provide a three-dimensional printing device that can correct the deviation in the irradiation position of the electron beam caused by the influence of ambient magnetic fields, thereby improving the printing accuracy of the molded product. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the three-dimensional modeling apparatus of the present disclosure forms a three-dimensional object by irradiating a powder for modeling with an electron beam and melting and solidifying the powder for modeling over multiple layers. The three-dimensional modeling apparatus includes an electron beam emission unit that irradiates the powder for modeling with the electron beam, an imaging unit that images an irradiation area of ​​the electron beam, and a control unit that, after irradiating a set irradiation reference point with the electron beam, images the irradiation area including the irradiation reference point using the imaging unit, calculates the position of an actual irradiation point of the electron beam based on the captured image, and corrects the irradiation position of the electron beam when forming the three-dimensional object in each layer based on a deviation between the calculated position of the actual irradiation point and the position of the irradiation reference point. Effect of the Invention

[0008] According to the three-dimensional printing apparatus of the present disclosure, it is possible to correct deviation in the irradiation position of the electron beam caused by the influence of the surrounding magnetic field, thereby improving the printing accuracy of the product. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view illustrating a schematic configuration of a three-dimensional modeling apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a plan view showing a modeling region in the three-dimensional printing apparatus according to the first embodiment; [Diagram 3] FIG. 2 is a plan view showing an irradiation reference point and an actual irradiation point in the three-dimensional printing apparatus according to the first embodiment; [Figure 4] 1 is a flowchart showing an example of an operation of the three-dimensional printing apparatus according to the first embodiment; [Diagram 5] FIG. 11 is a cross-sectional view illustrating a schematic configuration of a three-dimensional modeling apparatus according to a second embodiment. [Figure 6] 11 is a flowchart showing an example of the operation of the three-dimensional printing apparatus according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a three-dimensional modeling apparatus according to an embodiment will be described in detail with reference to the drawings.

[0011] Embodiment 1 FIG. 1 is a cross-sectional view showing a schematic configuration of a three-dimensional modeling apparatus 100 according to a first embodiment. In the three-dimensional modeling apparatus 100, after supplying the modeling powder A to the irradiation region 37, the modeling powder A is spread evenly. In the three-dimensional modeling apparatus 100, the modeling powder A is melted by irradiating the modeling powder A with an electron beam B, and then the molten modeling powder A is solidified. The three-dimensional modeling apparatus 100 repeats these operations to form a three-dimensional object C, which is a three-dimensional object formed by depositing the melted and solidified modeling powder A. An arrow L indicates the left direction, and an arrow R indicates the right direction.

[0012] The three-dimensional modeling apparatus 100 includes an electron beam emission unit 2, a modeling unit 3, a control unit 5, and a camera 51 as an imaging unit. In the following description, the up-down direction is a direction parallel to the direction in which the electron beam B is emitted from the electron beam emission unit 2, and corresponds to the vertical direction. The left-right direction is a direction perpendicular to the direction in which the electron beam B is emitted from the electron beam emission unit 2, and corresponds to the horizontal direction.

[0013] The electron beam emission unit 2 emits the electron beam B to irradiate the powder A for molding arranged in the irradiation region 37 with the electron beam B. When the powder A for molding is irradiated with the electron beam B, the powder A for molding melts and then solidifies. In addition, the electron beam emission unit 2 may irradiate the powder A for molding with the electron beam B before molding the three-dimensional object C, thereby preliminarily heating the powder A for molding.

[0014] The electron beam emission unit 2 includes an electron gun unit 21, a convergence coil 22, and a deflection coil 23. The electron gun unit 21, the convergence coil 22, and the deflection coil 23 are disposed, for example, inside a column 24 which is a housing of the electron beam emission unit 2 and has a cylindrical shape.

[0015] The electron gun section 21 is electrically connected to the control section 5. The electron gun section 21 receives a control signal transmitted from the control section 5 and operates based on the received control signal. The electron gun section 21 emits an electron beam B. For example, the electron gun section 21 emits the electron beam B toward a direction below the electron gun section 21. In the first embodiment, the electron gun section 21 emits the electron beam B vertically downward toward a direction below the electron gun section 21.

[0016] The convergence coil 22 is electrically connected to the control unit 5. The convergence coil 22 converges the electron beam B. The deflection coil 23 is electrically connected to the control unit 5. The deflection coil 23 receives a control signal transmitted from the control unit 5 and operates based on the received control signal. The deflection coil 23 adjusts the irradiation position of the electron beam B based on the control signal. The deflection coil 23 performs electromagnetic beam deflection of the electron beam B. Therefore, the deflection coil 23 can achieve a higher scanning speed during irradiation of the electron beam B compared to mechanical beam deflection.

[0017] The control unit 5 is an electronic control unit that controls the entire three-dimensional modeling apparatus 100. The control unit 5 is realized by a computer including, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The control unit 5 executes lift control of the lift stage 35, which is a control for lifting and lowering the lift stage 35 described later, opening and closing control of the shutter 41, operation control of the squeegee 33, emission control of the electron beam B, which is a control for emitting the electron beam B, and operation control of the deflection coil 23, which is a control for activating the deflection coil 23. Furthermore, the control unit 5 calculates a correction value from the difference between the irradiation reference point 38 and the actual irradiation point 39, and determines the amount of correction. The irradiation reference point 38 and the actual irradiation point 39 (see FIG. 3) will be described later.

[0018] The control unit 5 transmits a control signal to the shutter 41 to control the opening and closing of the shutter 41. The shutter 41 opens and closes by transmitting a control signal from the control unit 5 to the shutter 41. By opening and closing the shutter 41, the molding powder A flows out from the hopper 34, and a desired amount of the molding powder A is supplied onto the base plate 31 including the irradiation area 37 and the periphery of the irradiation area 37.

[0019] The control unit 5 operates the squeegee 33 before emitting the electron beam B. By operating the squeegee 33, the powder A for molding arranged on the base plate 31 is spread evenly.

[0020] The control unit 5 transmits a control signal to the deflection coil 23 to control the operation of the deflection coil 23. The irradiation position of the electron beam B is controlled based on the control signal transmitted from the control unit 5 to the deflection coil 23. For example, three-dimensional CAD (Computer-Aided Design) data of an object to be formed is input to the control unit 5. Based on the input three-dimensional CAD data, the control unit 5 generates two-dimensional slice data, which is data obtained when the three-dimensional object C to be formed is sliced ​​in two dimensions. The slice data is, for example, data of a horizontal cross section of the three-dimensional object C to be formed. The slice data is a collection of a large number of data corresponding to positions in the up-down direction.

[0021] The control unit 5 determines an irradiation area 37, which is an area where the powder A is irradiated with the electron beam B, based on the slice data. After determining the irradiation area 37, at least three irradiation reference points 38 are set in an area excluding the irradiation area 37 within the range of the formable area D. The formable area D is an area where a model can be formed by irradiating the electron beam B, and is wider than the irradiation area 37. The setting of the irradiation reference points 38 is not limited to three or more points, but if the setting of the irradiation reference points 38 is less than three points, the accuracy of the correction value may be low. The irradiation area 37 can be said to be a modeling area where the powder A is irradiated with the electron beam B to form a three-dimensional model C. Then, the control unit 5 transmits a control signal to the deflection coil 23 in accordance with the determined irradiation area 37.

[0022] The modeling unit 3 is a portion for modeling a desired three-dimensional object C. Modeling powder A is placed in the chamber 30. The modeling unit 3 includes a hopper 34, a shutter 41, a squeegee 33, a guide 43, a modeling box 36, an elevator 32, an elevator stage 35, and a base plate 31 inside the chamber 30. A vacuum pump, which is an exhaust device, is connected to the chamber 30. The vacuum pump is not shown. The inside of the chamber 30 is evacuated by the vacuum pump, so that the inside of the chamber 30 is in a vacuum or near-vacuum state.

[0023] The base plate 31 is disposed inside the modeling box 36, and serves as a base for the modeling powder A and the three-dimensional object C to be modeled. The three-dimensional object C is modeled on the base plate 31. The base plate 31 is, for example, a rectangular plate-like body. The base plate 31 is not limited to a rectangular plate-like body, and may be a circular plate-like body. The base plate 31 is provided, for example, such that the in-plane direction is horizontal. The base plate 31 is supported by the lifting stage 35 via the supporting powder layer 40. The base plate 31 moves up and down together with the lifting stage 35.

[0024] The elevator 32 is installed below the lift stage 35, and supports the lift stage 35 while raising and lowering the lift stage 35. The elevator 32 is electrically connected to the control unit 5. The elevator 32 receives a control signal transmitted from the control unit 5 and operates based on the received control signal. The elevator 32 moves the base plate 31 up and down together with the lift stage 35, thereby adjusting the position of the base plate 31 in the up and down direction.

[0025] For example, the elevator 32 moves the base plate 31 upward together with the elevator stage 35 in the early stage of modeling of the three-dimensional object C in the three-dimensional modeling apparatus 100. The elevator 32 lowers the base plate 31 every time the modeling powder A is layered by melting and solidifying the modeling powder A on the base plate 31. There are no particular limitations on the structure of the elevator 32 as long as it is capable of raising and lowering the base plate 31.

[0026] The hopper 34 is a storage tank that stores the molding powder A. The hopper 34 is supported at a predetermined height inside the chamber 30. The hopper 34 has a powder storage section (not shown) in which the molding powder A is stored, and a discharge port (not shown) that is formed at the bottom of the hopper 34, i.e., at the bottom of the powder storage section, and discharges the molding powder A to the outside of the hopper 34. The molding powder A discharged from the discharge port is supplied onto the base plate 31. Alternatively, the molding powder A discharged from the discharge port is supplied onto the base plate 31 by the squeegee 33.

[0027] The molding powder A is a powdered material that melts and solidifies to form a three-dimensional object C. The molding powder A is irradiated with the electron beam B emitted from the electron beam emission unit 2, whereby it is melted and solidified or sintered. As the molding powder A, for example, a metal powder is used. Specifically, titanium, nickel, cobalt, iron, copper, aluminum, or alloys containing these metals are often used, but the present invention is not limited to these.

[0028] The particle size of the modeling powder A is generally about 20 to 150 μm so that it can be sufficiently solidified by the electron beam B and a three-dimensional model C with high surface accuracy can be obtained, but is not limited to this.

[0029] The supporting powder layer 40 is disposed above the lifting stage 35, and is provided to support the base plate 31. The supporting powder layer 40 is composed of the molding powder A. The outermost surface of the supporting powder layer 40 is disposed at the same level as or lower than the outermost surface of the base plate 31. During molding, the molding powder A is spread evenly on the outermost surface of the supporting powder layer 40. Furthermore, for each layer during molding, the molding powder A is thinly spread evenly in the irradiation area 37 by the squeegee 33 to form the molding powder layer 42, which is then preheated and solidified by the electron beam B.

[0030] The squeegee 33 spreads the powder A for molding, which is disposed above the base plate 31, evenly on the base plate 31. The squeegee 33 is fastened to a guide 43, and is moved along the guide 43 by an actuator mechanism (not shown) in the left-right directions indicated by the arrows L and R, thereby spreading the powder A for molding evenly.

[0031] A camera 51 is provided to check for deviations in the irradiation position of the electron beam B due to the influence of the surrounding magnetic field. The camera 51 captures an image of the printable area D. FIG. 2 is a plan view showing the printable area D in the three-dimensional printing apparatus 100 according to the first embodiment. As described above, a plurality of irradiation reference points 38 are set in the printable area D. A plurality of irradiation reference points 38 are provided at any positions that do not interfere with the three-dimensional object C.

[0032] In order to form the irradiation reference point 38, the control unit 5 irradiates the electron beam B from the electron beam emission unit 2 based on the control signal, and forms the irradiation reference point 38. If the electron beam irradiation deviates from the irradiation reference point 38 due to the influence of the ambient magnetic field, an actual irradiation point 39 is formed at a position different from the irradiation reference point 38.

[0033] 3 is a plan view showing an irradiation reference point 38 and an actual irradiation point 39 in the three-dimensional printing apparatus 100 according to the first embodiment. The coordinates of the irradiation reference point 38 are (X0, Y0), and the coordinates of the actual irradiation point 39 are (Xr, Yr). When a deviation occurs between the coordinates (Xr, Yr) of the actual irradiation point 39 and the coordinates (X0, Y0) of the irradiation reference point 38, the control unit 5 calculates the deviation amount (ΔX, ΔY)=(X0-Xr, Y0-Yr). When a plurality of irradiation reference points 38 are provided, the deviation amount is calculated by using an average value of the deviation amounts between the plurality of irradiation reference points 38 and the plurality of actual irradiation points 39.

[0034] After the actual irradiation point 39 is modeled, the position of the actual irradiation point 39 is imaged and measured using a camera 51. As the camera 51, a camera having a resolution of less than 50 μm is preferable in order to measure the position of the actual irradiation point 39 more accurately. Therefore, it is preferable to use a high-resolution camera as the camera 51. In addition, it is preferable to attach the camera 51 to the upper part of the device so that the entire range of the modelable area D can be imaged.

[0035] After calculating the amount of deviation, i.e., the correction value, the electron beam B is irradiated again onto the set confirmation irradiation point to confirm whether the correction amount is appropriate. The confirmation irradiation point may be specified to be the same position as the irradiation reference point 38, or may be specified to be a different position. If the deviation is small and there is no correction value, the process of irradiating the confirmation irradiation point with the electron beam B and confirming the correction amount may be omitted.

[0036] 4 is a flowchart showing an example of the operation of the three-dimensional modeling apparatus 100 according to the first embodiment. First, the modeling powder A is supplied from the hopper 34 (step S101). Next, the squeegee 33 is moved to the squeegee start position (step S102), and the modeling powder A supplied from the hopper 34 is squeegeeed (step S103). Next, the presence or absence of a squeegeeing abnormality is confirmed (step S104). If there is no abnormality (step S104: Yes), the squeegeeing is completed, and the process proceeds to step S105. If there is a squeegeeing abnormality (step S104: No), the process returns to step S102 and squeegeeing is retried.

[0037] After the squeegeeing is completed, the laid molding powder A is irradiated with the electron beam B for preheating (step S105). It is confirmed whether the preheating is completed (step S106), and if the preheating is not completed (step S106: No), step S105 is executed again. If the preheating is completed (step S106: Yes), the electron beam B for calculating the correction value is irradiated from the electron gun unit 21 to the set irradiation reference point 38 (step S107). Next, the actual irradiation point 39, which is the irradiation position of the electron beam B, is imaged by the camera 51 (step S108).

[0038] The control unit 5 calculates the position of the actual irradiation point 39, which is the irradiation position of the electron beam B, based on the image captured by the camera 51 (step S109). The control unit 5 compares the position of the actual irradiation point 39 with the position of the set irradiation reference point 38, and calculates a correction amount, which is the amount of deviation between the position of the actual irradiation point 39 and the position of the set irradiation reference point 38. The control unit 5 reflects the calculated correction amount in the electron beam control (step S110). The control unit 5 irradiates the electron beam B reflecting the correction amount from the electron gun unit 21 to the confirmation irradiation point (step S111), and checks the position of the irradiated electron beam B using the camera 51 to check whether the correction amount is appropriate or not (step S112).

[0039] If the correction amount is not appropriate (step S112: No), the process returns to step S107, and the electron beam emission unit 2 is corrected again. If the correction amount is appropriate (step S112: Yes), the control unit 5 causes the electron beam B to be irradiated toward the powder layer on the modeling surface of the three-dimensional object C (step S113).

[0040] Thereafter, it is confirmed whether or not the modeling of all layers has been completed (step S114), and if it has been completed (step S114: Yes), the operation is terminated. If the modeling of all layers has not been completed (step S114: No), the lifting stage 35 is lowered by one layer (step S115), and the same process is repeated from step S101 until the modeling of all layers is completed.

[0041] In this way, according to embodiment 1, each time a layer is formed, the electron beam B is irradiated to a preset irradiation reference point 38, the position of the irradiated actual irradiation point 39 is measured using the camera 51, and the deviation between the irradiation reference point 38 and the actual irradiation point 39 is detected to correct the irradiation position of the electron beam B, thereby improving the forming accuracy of the formed product without being affected by the ambient magnetic field.

[0042] Embodiment 2 5 is a cross-sectional view illustrating a schematic configuration of a 3D printing apparatus 110 according to the second embodiment. The 3D printing apparatus 110 according to the second embodiment is provided with a plurality of cameras 51a and 51b. The configuration in the second embodiment is the same as that in the first embodiment except for the cameras 51a and 51b, and therefore a duplicated description will be omitted.

[0043] In the second embodiment, since multiple cameras 51a and 51b are installed to confirm the actual irradiation point 39, it is possible to accurately calculate the correction value even with a low-resolution camera. The cameras 51a and 51b are preferably attached to the top of the device, but may be attached to a part other than the top as long as the captured images can be combined.

[0044] FIG. 6 is a flowchart showing an example of the operation of the three-dimensional modeling apparatus 110 according to the second embodiment. Steps S101 to S107 and steps S110 to S115 are the same as those in the first embodiment, and therefore the overlapping explanations will be omitted. In step S107, the electron beam B for calculating the correction value is irradiated from the electron gun unit 21 to the irradiation reference point 38 set. Next, the actual irradiation point 39, which is the irradiation position of the electron beam B, is captured by the multiple cameras 51a and 51b (step S208). In the imaging in step S208, the imaging positions of the multiple cameras 51a and 51b are shifted to capture the image. Next, the multiple captured images captured by the multiple cameras 51a and 51b are combined (step S209). In step S209, the multiple captured images captured by the multiple cameras 51a and 51b are combined to improve the apparent resolution of the captured image. Next, the position of the actual irradiation point 39 is calculated based on the combined captured image (step S210). In the next step S110, as in embodiment 1, the position of the actual irradiation point 39 is compared with the position of the set irradiation reference point 38, a correction amount, which is the amount of deviation between the position of the actual irradiation point 39 and the position of the set irradiation reference point 38, is calculated, and the calculated correction amount is reflected in the electron beam control.

[0045] As described above, according to the second embodiment, the actual irradiation point 39 of the electron beam B is captured using the multiple cameras 51a and 51b, so that it is possible to accurately calculate the correction value even with a low-resolution camera.

[0046] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, or the embodiments may be combined with each other. Also, parts of the configurations may be omitted or modified without departing from the gist of the present disclosure. [Explanation of symbols]

[0047] 2 electron beam emission section, 3 modeling section, 5 control section, 21 electron gun section, 22 focusing coil, 23 deflection coil, 24 column, 30 chamber, 31 base plate, 32 elevator, 33 squeegee, 34 hopper, 35 lifting stage, 36 modeling box, 37 irradiation area, 38 irradiation reference point, 39 actual irradiation point, 40 supporting powder layer, 41 shutter, 42 modeling powder layer, 43 guide, 51, 51a, 51b camera, 100, 110 three-dimensional modeling device, A modeling powder, B electron beam, C three-dimensional model, D modelable area.

Claims

1. A three-dimensional modeling apparatus for forming a three-dimensional object by irradiating a powder for modeling with an electron beam and melting and solidifying the powder for modeling in a plurality of layers, comprising: an electron beam emission unit that irradiates the powder for molding with the electron beam; an imaging unit that images an area irradiated with the electron beam; a control unit that, after irradiating the electron beam to a set irradiation reference point, causes the imaging unit to capture an image of an irradiation area including the irradiation reference point, calculates a position of an actual irradiation point of the electron beam based on the captured image, and corrects the irradiation position of the electron beam when forming the three-dimensional object in each layer based on a deviation between the calculated position of the actual irradiation point and a position of the irradiation reference point. A three-dimensional modeling apparatus comprising:

2. The imaging unit is a camera having a resolution of less than 50 μm. The three-dimensional modeling apparatus according to claim 1 .

3. The imaging unit has a plurality of cameras, The control unit calculates a position of an actual irradiation point of the electron beam based on a captured image obtained by combining images captured by the multiple cameras. The three-dimensional modeling apparatus according to claim 1 or 2.

Images